An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration.
The rate at which oxygen is used by a tissue; microliters of oxygen STPD used per milligram of tissue per hour; the rate at which oxygen enters the blood from alveolar gas, equal in the steady state to the consumption of oxygen by tissue metabolism throughout the body. (Stedman, 25th ed, p346)
Molecules or ions formed by the incomplete one-electron reduction of oxygen. These reactive oxygen intermediates include SINGLET OXYGEN; SUPEROXIDES; PEROXIDES; HYDROXYL RADICAL; and HYPOCHLOROUS ACID. They contribute to the microbicidal activity of PHAGOCYTES, regulation of signal transduction and gene expression, and the oxidative damage to NUCLEIC ACIDS; PROTEINS; and LIPIDS.
Inhalation of oxygen aimed at restoring toward normal any pathophysiologic alterations of gas exchange in the cardiopulmonary system, as by the use of a respirator, nasal catheter, tent, chamber, or mask. (From Dorland, 27th ed & Stedman, 25th ed)
An excited state of molecular oxygen generated photochemically or chemically. Singlet oxygen reacts with a variety of biological molecules such as NUCLEIC ACIDS; PROTEINS; and LIPIDS; causing oxidative damages.
Stable oxygen atoms that have the same atomic number as the element oxygen, but differ in atomic weight. O-17 and 18 are stable oxygen isotopes.
The therapeutic intermittent administration of oxygen in a chamber at greater than sea-level atmospheric pressures (three atmospheres). It is considered effective treatment for air and gas embolisms, smoke inhalation, acute carbon monoxide poisoning, caisson disease, clostridial gangrene, etc. (From Segen, Dictionary of Modern Medicine, 1992). The list of treatment modalities includes stroke.
The pressure that would be exerted by one component of a mixture of gases if it were present alone in a container. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
Relatively complete absence of oxygen in one or more tissues.
A strong oxidizing agent used in aqueous solution as a ripening agent, bleach, and topical anti-infective. It is relatively unstable and solutions deteriorate over time unless stabilized by the addition of acetanilide or similar organic materials.
A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).
A disturbance in the prooxidant-antioxidant balance in favor of the former, leading to potential damage. Indicators of oxidative stress include damaged DNA bases, protein oxidation products, and lipid peroxidation products (Sies, Oxidative Stress, 1991, pxv-xvi).
The determination of oxygen-hemoglobin saturation of blood either by withdrawing a sample and passing it through a classical photoelectric oximeter or by electrodes attached to some translucent part of the body like finger, earlobe, or skin fold. It includes non-invasive oxygen monitoring by pulse oximetry.
Naturally occurring or synthetic substances that inhibit or retard the oxidation of a substance to which it is added. They counteract the harmful and damaging effects of oxidation in animal tissues.
A compound formed by the combination of hemoglobin and oxygen. It is a complex in which the oxygen is bound directly to the iron without causing a change from the ferrous to the ferric state.
A colorless, odorless gas that can be formed by the body and is necessary for the respiration cycle of plants and animals.
Life or metabolic reactions occurring in an environment containing oxygen.
An oxidoreductase that catalyzes the reaction between superoxide anions and hydrogen to yield molecular oxygen and hydrogen peroxide. The enzyme protects the cell against dangerous levels of superoxide. EC 1.15.1.1.
The oxygen-carrying proteins of ERYTHROCYTES. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements.
Highly reactive molecules with an unsatisfied electron valence pair. Free radicals are produced in both normal and pathological processes. They are proven or suspected agents of tissue damage in a wide variety of circumstances including radiation, damage from environment chemicals, and aging. Natural and pharmacological prevention of free radical damage is being actively investigated.
Substances that influence the course of a chemical reaction by ready combination with free radicals. Among other effects, this combining activity protects pancreatic islets against damage by cytokines and prevents myocardial and pulmonary perfusion injuries.
Semiautonomous, self-reproducing organelles that occur in the cytoplasm of all cells of most, but not all, eukaryotes. Each mitochondrion is surrounded by a double limiting membrane. The inner membrane is highly invaginated, and its projections are called cristae. Mitochondria are the sites of the reactions of oxidative phosphorylation, which result in the formation of ATP. They contain distinctive RIBOSOMES, transfer RNAs (RNA, TRANSFER); AMINO ACYL T RNA SYNTHETASES; and elongation and termination factors. Mitochondria depend upon genes within the nucleus of the cells in which they reside for many essential messenger RNAs (RNA, MESSENGER). Mitochondria are believed to have arisen from aerobic bacteria that established a symbiotic relationship with primitive protoeukaryotes. (King & Stansfield, A Dictionary of Genetics, 4th ed)
An oxidoreductase that catalyzes the conversion of HYDROGEN PEROXIDE to water and oxygen. It is present in many animal cells. A deficiency of this enzyme results in ACATALASIA.
An abnormal increase in the amount of oxygen in the tissues and organs.
A flavoprotein enzyme that catalyzes the univalent reduction of OXYGEN using NADPH as an electron donor to create SUPEROXIDE ANION. The enzyme is dependent on a variety of CYTOCHROMES. Defects in the production of superoxide ions by enzymes such as NADPH oxidase result in GRANULOMATOUS DISEASE, CHRONIC.
A condition of decreased oxygen content at the cellular level.
The complete absence, or (loosely) the paucity, of gaseous or dissolved elemental oxygen in a given place or environment. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)
Highly reactive compounds produced when oxygen is reduced by a single electron. In biological systems, they may be generated during the normal catalytic function of a number of enzymes and during the oxidation of hemoglobin to METHEMOGLOBIN. In living organisms, SUPEROXIDE DISMUTASE protects the cell from the deleterious effects of superoxides.
Measurement of oxygen and carbon dioxide in the blood.
An electrochemical technique for measuring the current that flows in solution as a function of an applied voltage. The observed polarographic wave, resulting from the electrochemical response, depends on the way voltage is applied (linear sweep or differential pulse) and the type of electrode used. Usually a mercury drop electrode is used.
Elements of limited time intervals, contributing to particular results or situations.
Techniques used for determining the values of photometric parameters of light resulting from LUMINESCENCE.
The rate dynamics in chemical or physical systems.
The exchange of OXYGEN and CARBON DIOXIDE between alveolar air and pulmonary capillary blood that occurs across the BLOOD-AIR BARRIER.
The chemical reactions involved in the production and utilization of various forms of energy in cells.
Substances that are used in place of blood, for example, as an alternative to BLOOD TRANSFUSIONS after blood loss to restore BLOOD VOLUME and oxygen-carrying capacity to the blood circulation, or to perfuse isolated organs.
The act of breathing with the LUNGS, consisting of INHALATION, or the taking into the lungs of the ambient air, and of EXHALATION, or the expelling of the modified air which contains more CARBON DIOXIDE than the air taken in (Blakiston's Gould Medical Dictionary, 4th ed.). This does not include tissue respiration (= OXYGEN CONSUMPTION) or cell respiration (= CELL RESPIRATION).
The noninvasive measurement or determination of the partial pressure (tension) of oxygen and/or carbon dioxide locally in the capillaries of a tissue by the application to the skin of a special set of electrodes. These electrodes contain photoelectric sensors capable of picking up the specific wavelengths of radiation emitted by oxygenated versus reduced hemoglobin.
Electron-accepting molecules in chemical reactions in which electrons are transferred from one molecule to another (OXIDATION-REDUCTION).
Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.
Unstable isotopes of oxygen that decay or disintegrate emitting radiation. O atoms with atomic weights 13, 14, 15, 19, and 20 are radioactive oxygen isotopes.
An iron-molybdenum flavoprotein containing FLAVIN-ADENINE DINUCLEOTIDE that oxidizes hypoxanthine, some other purines and pterins, and aldehydes. Deficiency of the enzyme, an autosomal recessive trait, causes xanthinuria.
A free radical gas produced endogenously by a variety of mammalian cells, synthesized from ARGININE by NITRIC OXIDE SYNTHASE. Nitric oxide is one of the ENDOTHELIUM-DEPENDENT RELAXING FACTORS released by the vascular endothelium and mediates VASODILATION. It also inhibits platelet aggregation, induces disaggregation of aggregated platelets, and inhibits platelet adhesion to the vascular endothelium. Nitric oxide activates cytosolic GUANYLATE CYCLASE and thus elevates intracellular levels of CYCLIC GMP.
Nitrogenous products of NITRIC OXIDE synthases, ranging from NITRIC OXIDE to NITRATES. These reactive nitrogen intermediates also include the inorganic PEROXYNITROUS ACID and the organic S-NITROSOTHIOLS.
The N-acetyl derivative of CYSTEINE. It is used as a mucolytic agent to reduce the viscosity of mucous secretions. It has also been shown to have antiviral effects in patients with HIV due to inhibition of viral stimulation by reactive oxygen intermediates.
A tripeptide with many roles in cells. It conjugates to drugs to make them more soluble for excretion, is a cofactor for some enzymes, is involved in protein disulfide bond rearrangement and reduces peroxides.
The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH = log 1/2[1/(H+)], where (H+) is the hydrogen ion concentration in gram equivalents per liter of solution. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.
Controlled physical activity which is performed in order to allow assessment of physiological functions, particularly cardiovascular and pulmonary, but also aerobic capacity. Maximal (most intense) exercise is usually required but submaximal exercise is also used.
The movement and the forces involved in the movement of the blood through the CARDIOVASCULAR SYSTEM.
The process by which ELECTRONS are transported from a reduced substrate to molecular OXYGEN. (From Bennington, Saunders Dictionary and Encyclopedia of Laboratory Medicine and Technology, 1984, p270)
One of the mechanisms by which CELL DEATH occurs (compare with NECROSIS and AUTOPHAGOCYTOSIS). Apoptosis is the mechanism responsible for the physiological deletion of cells and appears to be intrinsically programmed. It is characterized by distinctive morphologic changes in the nucleus and cytoplasm, chromatin cleavage at regularly spaced sites, and the endonucleolytic cleavage of genomic DNA; (DNA FRAGMENTATION); at internucleosomal sites. This mode of cell death serves as a balance to mitosis in regulating the size of animal tissues and in mediating pathologic processes associated with tumor growth.
A technique applicable to the wide variety of substances which exhibit paramagnetism because of the magnetic moments of unpaired electrons. The spectra are useful for detection and identification, for determination of electron structure, for study of interactions between molecules, and for measurement of nuclear spins and moments. (From McGraw-Hill Encyclopedia of Science and Technology, 7th edition) Electron nuclear double resonance (ENDOR) spectroscopy is a variant of the technique which can give enhanced resolution. Electron spin resonance analysis can now be used in vivo, including imaging applications such as MAGNETIC RESONANCE IMAGING.
Hypoxia-inducible factor 1, alpha subunit is a basic helix-loop-helix transcription factor that is regulated by OXYGEN availability and is targeted for degradation by VHL TUMOR SUPPRESSOR PROTEIN.
2,3-Diphosphoglycerate (2,3-DPG) is a physiological modulator of hemoglobin oxygen affinity, reducing its attraction to oxygen in red blood cells, which facilitates the release of oxygen to tissues with lower oxygen concentrations.
The univalent radical OH. Hydroxyl radical is a potent oxidizing agent.
The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway.
A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement.
A normal intermediate in the fermentation (oxidation, metabolism) of sugar. The concentrated form is used internally to prevent gastrointestinal fermentation. (From Stedman, 26th ed)
The number of times the HEART VENTRICLES contract per unit of time, usually per minute.
Peroxidase catalyzed oxidation of lipids using hydrogen peroxide as an electron acceptor.
A multisubunit enzyme complex containing CYTOCHROME A GROUP; CYTOCHROME A3; two copper atoms; and 13 different protein subunits. It is the terminal oxidase complex of the RESPIRATORY CHAIN and collects electrons that are transferred from the reduced CYTOCHROME C GROUP and donates them to molecular OXYGEN, which is then reduced to water. The redox reaction is simultaneously coupled to the transport of PROTONS across the inner mitochondrial membrane.
Electrodes which can be used to measure the concentration of particular ions in cells, tissues, or solutions.
A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.
The circulation of blood through the BLOOD VESSELS of the BRAIN.
Expenditure of energy during PHYSICAL ACTIVITY. Intensity of exertion may be measured by rate of OXYGEN CONSUMPTION; HEAT produced, or HEART RATE. Perceived exertion, a psychological measure of exertion, is included.
The class of all enzymes catalyzing oxidoreduction reactions. The substrate that is oxidized is regarded as a hydrogen donor. The systematic name is based on donor:acceptor oxidoreductase. The recommended name will be dehydrogenase, wherever this is possible; as an alternative, reductase can be used. Oxidase is only used in cases where O2 is the acceptor. (Enzyme Nomenclature, 1992, p9)
Carbon monoxide (CO). A poisonous colorless, odorless, tasteless gas. It combines with hemoglobin to form carboxyhemoglobin, which has no oxygen carrying capacity. The resultant oxygen deprivation causes headache, dizziness, decreased pulse and respiratory rates, unconsciousness, and death. (From Merck Index, 11th ed)
The span of viability of a cell characterized by the capacity to perform certain functions such as metabolism, growth, reproduction, some form of responsiveness, and adaptability.
The voltage difference, normally maintained at approximately -180mV, across the INNER MITOCHONDRIAL MEMBRANE, by a net movement of positive charge across the membrane. It is a major component of the PROTON MOTIVE FORCE in MITOCHONDRIA used to drive the synthesis of ATP.
Heterocyclic compounds in which an oxygen is attached to a cyclic nitrogen.
The mixture of gases present in the earth's atmosphere consisting of oxygen, nitrogen, carbon dioxide, and small amounts of other gases.
A noninvasive technique that uses the differential absorption properties of hemoglobin and myoglobin to evaluate tissue oxygenation and indirectly can measure regional hemodynamics and blood flow. Near-infrared light (NIR) can propagate through tissues and at particular wavelengths is differentially absorbed by oxygenated vs. deoxygenated forms of hemoglobin and myoglobin. Illumination of intact tissue with NIR allows qualitative assessment of changes in the tissue concentration of these molecules. The analysis is also used to determine body composition.
A conjugated protein which is the oxygen-transporting pigment of muscle. It is made up of one globin polypeptide chain and one heme group.
The volume of BLOOD passing through the HEART per unit of time. It is usually expressed as liters (volume) per minute so as not to be confused with STROKE VOLUME (volume per beat).
Helium. A noble gas with the atomic symbol He, atomic number 2, and atomic weight 4.003. It is a colorless, odorless, tasteless gas that is not combustible and does not support combustion. It was first detected in the sun and is now obtained from natural gas. Medically it is used as a diluent for other gases, being especially useful with oxygen in the treatment of certain cases of respiratory obstruction, and as a vehicle for general anesthetics. (Dorland, 27th ed)
Physical activity which is usually regular and done with the intention of improving or maintaining PHYSICAL FITNESS or HEALTH. Contrast with PHYSICAL EXERTION which is concerned largely with the physiologic and metabolic response to energy expenditure.
The relationship between the dose of an administered drug and the response of the organism to the drug.
The art or process of comparing photometrically the relative intensities of the light in different parts of the spectrum.
The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.
A vertical distance measured from a known level on the surface of a planet or other celestial body.
The flow of BLOOD through or around an organ or region of the body.
Ions with the suffix -onium, indicating cations with coordination number 4 of the type RxA+ which are analogous to QUATERNARY AMMONIUM COMPOUNDS (H4N+). Ions include phosphonium R4P+, oxonium R3O+, sulfonium R3S+, chloronium R2Cl+
A basic helix-loop-helix transcription factor that plays a role in APOPTOSIS. It is composed of two subunits: ARYL HYDROCARBON RECEPTOR NUCLEAR TRANSLOCATOR and HYPOXIA-INDUCIBLE FACTOR 1, ALPHA SUBUNIT.
Salts or esters of LACTIC ACID containing the general formula CH3CHOHCOOR.
The color-furnishing portion of hemoglobin. It is found free in tissues and as the prosthetic group in many hemeproteins.
Either of the pair of organs occupying the cavity of the thorax that effect the aeration of the blood.
Porphyrins which are combined with a metal ion. The metal is bound equally to all four nitrogen atoms of the pyrrole rings. They possess characteristic absorption spectra which can be utilized for identification or quantitative estimation of porphyrins and porphyrin-bound compounds.
Nitrogen oxide (N2O). A colorless, odorless gas that is used as an anesthetic and analgesic. High concentrations cause a narcotic effect and may replace oxygen, causing death by asphyxia. It is also used as a food aerosol in the preparation of whipping cream.
A metallic element with atomic symbol Fe, atomic number 26, and atomic weight 55.85. It is an essential constituent of HEMOGLOBINS; CYTOCHROMES; and IRON-BINDING PROTEINS. It plays a role in cellular redox reactions and in the transport of OXYGEN.
PRESSURE of the BLOOD on the ARTERIES and other BLOOD VESSELS.
A six carbon compound related to glucose. It is found naturally in citrus fruits and many vegetables. Ascorbic acid is an essential nutrient in human diets, and necessary to maintain connective tissue and bone. Its biologically active form, vitamin C, functions as a reducing agent and coenzyme in several metabolic pathways. Vitamin C is considered an antioxidant.
The exercise capacity of an individual as measured by endurance (maximal exercise duration and/or maximal attained work load) during an EXERCISE TEST.
The termination of the cell's ability to carry out vital functions such as metabolism, growth, reproduction, responsiveness, and adaptability.
A subtype of striated muscle, attached by TENDONS to the SKELETON. Skeletal muscles are innervated and their movement can be consciously controlled. They are also called voluntary muscles.
A clear, odorless, tasteless liquid that is essential for most animal and plant life and is an excellent solvent for many substances. The chemical formula is hydrogen oxide (H2O). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.
The non-genetic biological changes of an organism in response to challenges in its ENVIRONMENT.
That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.
An adenine nucleotide containing three phosphate groups esterified to the sugar moiety. In addition to its crucial roles in metabolism adenosine triphosphate is a neurotransmitter.
A highly anionic organic phosphate which is present in human red blood cells at about the same molar ratio as hemoglobin. It binds to deoxyhemoglobin but not the oxygenated form, therefore diminishing the oxygen affinity of hemoglobin. This is essential in enabling hemoglobin to unload oxygen in tissue capillaries. It is also an intermediate in the conversion of 3-phosphoglycerate to 2-phosphoglycerate by phosphoglycerate mutase (EC 5.4.2.1). (From Stryer Biochemistry, 4th ed, p160; Enzyme Nomenclature, 1992, p508)
Any disorder marked by obstruction of conducting airways of the lung. AIRWAY OBSTRUCTION may be acute, chronic, intermittent, or persistent.
Hemoglobins characterized by structural alterations within the molecule. The alteration can be either absence, addition or substitution of one or more amino acids in the globin part of the molecule at selected positions in the polypeptide chains.
Inorganic compounds that contain the OH- group.
Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.
A group of compounds that contain a bivalent O-O group, i.e., the oxygen atoms are univalent. They can either be inorganic or organic in nature. Such compounds release atomic (nascent) oxygen readily. Thus they are strong oxidizing agents and fire hazards when in contact with combustible materials, especially under high-temperature conditions. The chief industrial uses of peroxides are as oxidizing agents, bleaching agents, and initiators of polymerization. (From Hawley's Condensed Chemical Dictionary, 11th ed)
The pressure at any point in an atmosphere due solely to the weight of the atmospheric gases above the point concerned.
A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.
A group of oxidoreductases that act on NADH or NADPH. In general, enzymes using NADH or NADPH to reduce a substrate are classified according to the reverse reaction, in which NAD+ or NADP+ is formally regarded as an acceptor. This subclass includes only those enzymes in which some other redox carrier is the acceptor. (Enzyme Nomenclature, 1992, p100) EC 1.6.
Peroxidases are enzymes that catalyze the reduction of hydrogen peroxide to water, while oxidizing various organic and inorganic compounds, playing crucial roles in diverse biological processes including stress response, immune defense, and biosynthetic reactions.
The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)
Naturally occurring or experimentally induced animal diseases with pathological processes sufficiently similar to those of human diseases. They are used as study models for human diseases.
An activity in which the organism plunges into water. It includes scuba and bell diving. Diving as natural behavior of animals goes here, as well as diving in decompression experiments with humans or animals.
The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.
Inorganic or organic salts and esters of nitric acid. These compounds contain the NO3- radical.
A purine base found in most body tissues and fluids, certain plants, and some urinary calculi. It is an intermediate in the degradation of adenosine monophosphate to uric acid, being formed by oxidation of hypoxanthine. The methylated xanthine compounds caffeine, theobromine, and theophylline and their derivatives are used in medicine for their bronchodilator effects. (Dorland, 28th ed)
Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.
The mitochondria of the myocardium.
Molecules which contain an atom or a group of atoms exhibiting an unpaired electron spin that can be detected by electron spin resonance spectroscopy and can be bonded to another molecule. (McGraw-Hill Dictionary of Chemical and Technical Terms, 4th ed)
Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes.
Drugs that are pharmacologically inactive but when exposed to ultraviolet radiation or sunlight are converted to their active metabolite to produce a beneficial reaction affecting the diseased tissue. These compounds can be administered topically or systemically and have been used therapeutically to treat psoriasis and various types of neoplasms.
The synthesis by organisms of organic chemical compounds, especially carbohydrates, from carbon dioxide using energy obtained from light rather than from the oxidation of chemical compounds. Photosynthesis comprises two separate processes: the light reactions and the dark reactions. In higher plants; GREEN ALGAE; and CYANOBACTERIA; NADPH and ATP formed by the light reactions drive the dark reactions which result in the fixation of carbon dioxide. (from Oxford Dictionary of Biochemistry and Molecular Biology, 2001)
Reduction of blood viscosity usually by the addition of cell free solutions. Used clinically (1) in states of impaired microcirculation, (2) for replacement of intraoperative blood loss without homologous blood transfusion, and (3) in cardiopulmonary bypass and hypothermia.
An enzyme catalyzing the oxidation of 2 moles of glutathione in the presence of hydrogen peroxide to yield oxidized glutathione and water. EC 1.11.1.9.
Testing for the amount of biodegradable organic material in a water sample by measuring the quantity of oxygen consumed by biodegradation of those materials over a specific time period.
A coenzyme composed of ribosylnicotinamide 5'-diphosphate coupled to adenosine 5'-phosphate by pyrophosphate linkage. It is found widely in nature and is involved in numerous enzymatic reactions in which it serves as an electron carrier by being alternately oxidized (NAD+) and reduced (NADH). (Dorland, 27th ed)
A metabolic process that converts GLUCOSE into two molecules of PYRUVIC ACID through a series of enzymatic reactions. Energy generated by this process is conserved in two molecules of ATP. Glycolysis is the universal catabolic pathway for glucose, free glucose, or glucose derived from complex CARBOHYDRATES, such as GLYCOGEN and STARCH.
Established cell cultures that have the potential to propagate indefinitely.
Inbred C57BL mice are a strain of laboratory mice that have been produced by many generations of brother-sister matings, resulting in a high degree of genetic uniformity and homozygosity, making them widely used for biomedical research, including studies on genetics, immunology, cancer, and neuroscience.
Conversion of an inactive form of an enzyme to one possessing metabolic activity. It includes 1, activation by ions (activators); 2, activation by cofactors (coenzymes); and 3, conversion of an enzyme precursor (proenzyme or zymogen) to an active enzyme.
The volume of packed RED BLOOD CELLS in a blood specimen. The volume is measured by centrifugation in a tube with graduated markings, or with automated blood cell counters. It is an indicator of erythrocyte status in disease. For example, ANEMIA shows a low value; POLYCYTHEMIA, a high value.
Any method of artificial breathing that employs mechanical or non-mechanical means to force the air into and out of the lungs. Artificial respiration or ventilation is used in individuals who have stopped breathing or have RESPIRATORY INSUFFICIENCY to increase their intake of oxygen (O2) and excretion of carbon dioxide (CO2).
An element with the atomic symbol N, atomic number 7, and atomic weight [14.00643; 14.00728]. Nitrogen exists as a diatomic gas and makes up about 78% of the earth's atmosphere by volume. It is a constituent of proteins and nucleic acids and found in all living cells.
The time span between the beginning of physical activity by an individual and the termination because of exhaustion.
A cell line derived from cultured tumor cells.
Failure to adequately provide oxygen to cells of the body and to remove excess carbon dioxide from them. (Stedman, 25th ed)
A bilateral retinopathy occurring in premature infants treated with excessively high concentrations of oxygen, characterized by vascular dilatation, proliferation, and tortuosity, edema, and retinal detachment, with ultimate conversion of the retina into a fibrous mass that can be seen as a dense retrolental membrane. Usually growth of the eye is arrested and may result in microophthalmia, and blindness may occur. (Dorland, 27th ed)
A mixed-function oxygenase that catalyzes the hydroxylation of a prolyl-glycyl containing peptide, usually in PROTOCOLLAGEN, to a hydroxyprolylglycyl-containing-peptide. The enzyme utilizes molecular OXYGEN with a concomitant oxidative decarboxylation of 2-oxoglutarate to SUCCINATE. The enzyme occurs as a tetramer of two alpha and two beta subunits. The beta subunit of procollagen-proline dioxygenase is identical to the enzyme PROTEIN DISULFIDE-ISOMERASES.
The vapor state of matter; nonelastic fluids in which the molecules are in free movement and their mean positions far apart. Gases tend to expand indefinitely, to diffuse and mix readily with other gases, to have definite relations of volume, temperature, and pressure, and to condense or liquefy at low temperatures or under sufficient pressure. (Grant & Hackh's Chemical Dictionary, 5th ed)
An enzyme of the oxidoreductase class that catalyzes the conversion of beta-D-glucose and oxygen to D-glucono-1,5-lactone and peroxide. It is a flavoprotein, highly specific for beta-D-glucose. The enzyme is produced by Penicillium notatum and other fungi and has antibacterial activity in the presence of glucose and oxygen. It is used to estimate glucose concentration in blood or urine samples through the formation of colored dyes by the hydrogen peroxide produced in the reaction. (From Enzyme Nomenclature, 1992) EC 1.1.3.4.
A large increase in oxygen uptake by neutrophils and most types of tissue macrophages through activation of an NADPH-cytochrome b-dependent oxidase that reduces oxygen to a superoxide. Individuals with an inherited defect in which the oxidase that reduces oxygen to superoxide is decreased or absent (GRANULOMATOUS DISEASE, CHRONIC) often die as a result of recurrent bacterial infections.
The circulation of the BLOOD through the MICROVASCULAR NETWORK.
A reduction in brain oxygen supply due to ANOXEMIA (a reduced amount of oxygen being carried in the blood by HEMOGLOBIN), or to a restriction of the blood supply to the brain, or both. Severe hypoxia is referred to as anoxia, and is a relatively common cause of injury to the central nervous system. Prolonged brain anoxia may lead to BRAIN DEATH or a PERSISTENT VEGETATIVE STATE. Histologically, this condition is characterized by neuronal loss which is most prominent in the HIPPOCAMPUS; GLOBUS PALLIDUS; CEREBELLUM; and inferior olives.
RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.
The circulation of the BLOOD through the LUNGS.
Treatment process involving the injection of fluid into an organ or tissue.
Proteins that contain an iron-porphyrin, or heme, prosthetic group resembling that of hemoglobin. (From Lehninger, Principles of Biochemistry, 1982, p480)
The restoration to life or consciousness of one apparently dead. (Dorland, 27th ed)

Arterial blood gas tensions during upper gastrointestinal endoscopy. (1/22785)

Arterial blood gas tensions were measured before and during upper gastrointestinal endoscopy, with (group I) and without (group 2) sedation with intravenous diazepam. There was a highly significant fall in the PaO2, which occurred in both groups and was therefore not attributable to diazepam. Measurement of FEV, and FVC before endoscopy had no predictive value for those patients whose PaO2 fell the most.  (+info)

In vitro development of sheep preantral follicles. (2/22785)

Preantral ovarian follicles isolated from prepubertal sheep ovaries were individually cultured for 6 days in the presence of increasing doses of FSH (ranging from 0.01 to 1 microg/ml) and under two different oxygen concentrations, 20% and 5% O2. Follicle development was evaluated on the basis of antral cavity formation as well as the presence of healthy cumulus oocyte complexes. Follicle growth was enhanced by FSH addition to culture medium, while the use of a low oxygen concentration slightly stimulated this process. However, when follicles were cultured in the presence of high doses of FSH (1 microgram/ml) and under low oxygen concentration, a high proportion of them showed the presence of an antral cavity and of a healthy cumulus-oocyte complex. In addition, under this specific culture condition sheep preantral follicles released higher levels of estradiol as compared to those secreted at lower FSH concentrations or under 20% O2. When the meiotic competence of oocytes derived from follicles cultured at 1 microgram/ml FSH was assessed, no significant difference was recorded between the two oxygen groups. These results show that the culture conditions here identified are beneficial to in vitro growth and differentiation of sheep preantral follicles.  (+info)

Endogenous plasma endothelin concentrations and coronary circulation in patients with mild dilated cardiomyopathy. (3/22785)

OBJECTIVE: To determine whether increased plasma concentrations of endothelin-1 (ET-1) and big endothelin (BET) play a role in the regulation of coronary circulation in patients with idiopathic dilated cardiomyopathy (IDCM). SETTING: Tertiary referral centre for cardiac diseases. PATIENTS: Fourteen patients (eight male/six female; mean (SD) age 59 (9) years) with IDCM (ejection fraction 36 (9)%) and five normotensive subjects (two male/three female; age 52 (7) years) serving as controls were studied. METHODS: Functional status was classified according to New York Heart Association (NYHA) class. Endogenous ET-1 and BET plasma concentrations from the aorta and the coronary sinus were determined by radioimmunoassay. Coronary blood flow, using the inert chromatographic argon method, myocardial oxygen consumption, and coronary sinus oxygen content under basal conditions were determined. RESULTS: In the aorta, mean (SD) concentrations of ET-1 (IDCM 0.76 (0.25) v controls 0.31 (0.06) fmol/ml; p = 0.002) and BET (IDCM 3.58 (1.06) v controls 2.11 (0.58) fmol/ml; p = 0.014) were increased in patients with IDCM. Aortic ET-1 concentrations correlated positively with NYHA class (r = 0. 731; p < 0.001), myocardial oxygen consumption (r = 0.749; p < 0. 001), and coronary blood flow (r = 0.645; p = 0.003), but inversely with coronary sinus oxygen content (r = -0.633; p = 0.004), which was significantly decreased in IDCM patients (IDCM 4.68 (1.05) v controls 6.70 (1.06) vol%; p = 0.003). CONCLUSIONS: The coronary circulation in patients with IDCM is exposed to an increased endothelin load. ET-1 concentrations correlate with functional deterioration. A decrease of the coronary sinus content of oxygen suggests a mismatch between coronary blood flow and metabolic demand. Thus, ET-1 might be a marker of a disequilibrium between myocardial oxygen demand and coronary blood flow in IDCM.  (+info)

Quantification of tumour vasculature and hypoxia by immunohistochemical staining and HbO2 saturation measurements. (4/22785)

Despite the possibility that tumour hypoxia may limit radiotherapeutic response, the underlying mechanisms remain poorly understood. A new methodology has been developed in which information from several sophisticated techniques is combined and analysed at a microregional level. First, tumour oxygen availability is spatially defined by measuring intravascular blood oxygen saturations (HbO2) cryospectrophotometrically in frozen tumour blocks. Second, hypoxic development is quantified in adjacent sections using immunohistochemical detection of a fluorescently conjugated monoclonal antibody (ELK3-51) to a nitroheterocyclic hypoxia marker (EF5), thereby providing information relating to both the oxygen consumption rates and the effective oxygen diffusion distances. Third, a combination of fluorescent (Hoechst 33342 or DiOC7(3)) and immunohistological (PECAM-1/CD31) stains is used to define the anatomical vascular densities and the fraction of blood vessels containing flow. Using a computer-interfaced microscope stage, image analysis software and a 3-CCD colour video camera, multiple images are digitized, combined to form a photo-montage and revisited after each of the three staining protocols. By applying image registration techniques, the spatial distribution of HbO2 saturations is matched to corresponding hypoxic marker intensities in adjacent sections. This permits vascular configuration to be related to oxygen availability and allows the hypoxic marker intensities to be quantitated in situ.  (+info)

The respiratory responses of Carcinus maenas to declining oxygen tension. (5/22785)

The degree of respiratory independence shown by Carcinus under conditions of declining oxygen tension is dependent on the animal's level of activity. Inactive Carcinus are capable of maintaining respiratory independence down to a Po2 of 60-80 mmHg. This is achieved primarily by an increase in ventilation volume such that the amount of oxygen made available at the respiratory surfaces remains constant over a wide range of oxygen tension. The Po2 at which this can no longer be maintained corresponds closely to the Po2 at which respiratory independence is lost. Under normoxic conditions the Po2 of the post- and prebranchial blood was 97 and 18 mmHg respectively. At the high oxygen tensions prevailing in the postbranchial blood the respiratory pigment is fully saturated. Under conditions of declining oxygen tension the heart rate remains more or less constant until the Po2 reaches 60-80 mmHg, the onset of bradycardia coinciding with the loss of saturation of the haemocyanin. Although cardiac output falls during hypoxia, the capacity rate ratio remains approximately constant, which enables the effectiveness of oxygen uptake by the blood to remain at a high level.  (+info)

Active transport of calcium across the isolated midgut of Hyalophora cecropia. (6/22785)

1. The net flux of 45Ca from lumen to blood side across the isolated and short-circuited Cecropia midgut was 1-9 +/- 0-2 muequiv. cm-2h-1 in 8 mM Ca and the flux ratio was as high as 56 to 1. 2. The calcium influx was depressed by anoxia; 73% after 30 min. 3. The kinetics of Ca transport were anomalous; the apparent Km varied with Ca concentration from less than 0-2 to greater than 5-6 mM Ca and the apparent Vmax varied from less than 1-3 to greater than 3-3 muequiv. cm-2h-1. 4. The calcium influx showed a delay before the tracer steady state was attained, indicating the existence in the transport route of a calcium pool equivalent to 5-7 muequiv/g. wet weight of midgut tissue. 5 High calcium (16 mM) depressed the short-circuit current and potassium transport from blood to lumen side across the midgut. 6. Calcium depressed magnesium transport, from lumen to blood side across the midgut, and magnesium depressed the calcium transport. 7. Ca transport by the midgut does not regulate the Ca level in the haemolymph in vivo; it merely aids the diffusion of calcium down its electrochemical gradient. However, Ca transport may assist the uptake of the nutrients from the midgut contents.  (+info)

2,3 diphosphoglycerate in Parkinson's disease. (7/22785)

The red cell 2,3 DPG, the most important factor for oxygen delivery in the tissues, was found to be increased in Parkinsonism patients compared with controls. The aging process seems not to be a factor in the increased 2,3 DPG concentration. Other factors relevant to raised 2,3 DPG level such as physical activity, increased oxygen requirements, and metabolic changes are discussed.  (+info)

Nitric oxide inhibits cardiac energy production via inhibition of mitochondrial creatine kinase. (8/22785)

Nitric oxide biosynthesis in cardiac muscle leads to a decreased oxygen consumption and lower ATP synthesis. It is suggested that this effect of nitric oxide is mainly due to the inhibition of the mitochondrial respiratory chain enzyme, cytochrome c oxidase. However, this work demonstrates that nitric oxide is able to inhibit soluble mitochondrial creatine kinase (CK), mitochondrial CK bound in purified mitochondria, CK in situ in skinned fibres as well as the functional activity of mitochondrial CK in situ in skinned fibres. Since mitochondrial isoenzyme is functionally coupled to oxidative phosphorylation, its inhibition also leads to decreased sensitivity of mitochondrial respiration to ADP and thus decreases ATP synthesis and oxygen consumption under physiological ADP concentrations.  (+info)

Oxygen is a colorless, odorless, tasteless gas that constitutes about 21% of the earth's atmosphere. It is a crucial element for human and most living organisms as it is vital for respiration. Inhaled oxygen enters the lungs and binds to hemoglobin in red blood cells, which carries it to tissues throughout the body where it is used to convert nutrients into energy and carbon dioxide, a waste product that is exhaled.

Medically, supplemental oxygen therapy may be provided to patients with conditions such as chronic obstructive pulmonary disease (COPD), pneumonia, heart failure, or other medical conditions that impair the body's ability to extract sufficient oxygen from the air. Oxygen can be administered through various devices, including nasal cannulas, face masks, and ventilators.

Oxygen consumption, also known as oxygen uptake, is the amount of oxygen that is consumed or utilized by the body during a specific period of time, usually measured in liters per minute (L/min). It is a common measurement used in exercise physiology and critical care medicine to assess an individual's aerobic metabolism and overall health status.

In clinical settings, oxygen consumption is often measured during cardiopulmonary exercise testing (CPET) to evaluate cardiovascular function, pulmonary function, and exercise capacity in patients with various medical conditions such as heart failure, chronic obstructive pulmonary disease (COPD), and other respiratory or cardiac disorders.

During exercise, oxygen is consumed by the muscles to generate energy through a process called oxidative phosphorylation. The amount of oxygen consumed during exercise can provide important information about an individual's fitness level, exercise capacity, and overall health status. Additionally, measuring oxygen consumption can help healthcare providers assess the effectiveness of treatments and rehabilitation programs in patients with various medical conditions.

Reactive Oxygen Species (ROS) are highly reactive molecules containing oxygen, including peroxides, superoxide, hydroxyl radical, and singlet oxygen. They are naturally produced as byproducts of normal cellular metabolism in the mitochondria, and can also be generated by external sources such as ionizing radiation, tobacco smoke, and air pollutants. At low or moderate concentrations, ROS play important roles in cell signaling and homeostasis, but at high concentrations, they can cause significant damage to cell structures, including lipids, proteins, and DNA, leading to oxidative stress and potential cell death.

Oxygen inhalation therapy is a medical treatment that involves the administration of oxygen to a patient through a nasal tube or mask, with the purpose of increasing oxygen concentration in the body. This therapy is used to treat various medical conditions such as chronic obstructive pulmonary disease (COPD), pneumonia, heart failure, and other conditions that cause low levels of oxygen in the blood. The additional oxygen helps to improve tissue oxygenation, reduce work of breathing, and promote overall patient comfort and well-being. Oxygen therapy may be delivered continuously or intermittently, depending on the patient's needs and medical condition.

Singlet oxygen, also known as excited oxygen or oxygen triplet state, is a variant of molecular oxygen (O2) with unusual chemical and physical properties. In its ground state, molecular oxygen consists of two atoms with parallel spins, forming a triplet state. However, singlet oxygen has both atoms in a spin-paired configuration, which makes it more reactive than the ground state oxygen.

In biomedical terms, singlet oxygen is often generated during normal cellular metabolism or under pathological conditions such as inflammation and oxidative stress. It can react with various biological molecules, including lipids, proteins, and DNA, leading to damage and dysfunction of cells and tissues. Therefore, singlet oxygen has been implicated in the development and progression of several diseases, such as atherosclerosis, neurodegenerative disorders, and cancer.

It is worth noting that singlet oxygen can also be used in medical applications, such as photodynamic therapy (PDT), where it is generated by light-activated drugs to selectively destroy cancer cells or bacteria.

Oxygen isotopes are different forms or varieties of the element oxygen that have the same number of protons in their atomic nuclei, which is 8, but a different number of neutrons. The most common oxygen isotopes are oxygen-16 (^{16}O), which contains 8 protons and 8 neutrons, and oxygen-18 (^{18}O), which contains 8 protons and 10 neutrons.

The ratio of these oxygen isotopes can vary in different substances, such as water molecules, and can provide valuable information about the origins and history of those substances. For example, scientists can use the ratio of oxygen-18 to oxygen-16 in ancient ice cores or fossilized bones to learn about past climate conditions or the diets of ancient organisms.

In medical contexts, oxygen isotopes may be used in diagnostic tests or treatments, such as positron emission tomography (PET) scans, where a radioactive isotope of oxygen (such as oxygen-15) is introduced into the body and emits positrons that can be detected by specialized equipment to create detailed images of internal structures.

Hyperbaric oxygenation is a medical treatment in which a patient breathes pure oxygen in a pressurized chamber, typically at greater than one atmosphere absolute (ATA). This process results in increased levels of oxygen being dissolved in the blood and delivered to body tissues, thereby promoting healing, reducing inflammation, and combating infection. Hyperbaric oxygen therapy is used to treat various medical conditions, including carbon monoxide poisoning, decompression sickness, gangrene, and wounds that are slow to heal due to diabetes or radiation injury.

In the context of medicine, and specifically in physiology and respiratory therapy, partial pressure (P or p) is a measure of the pressure exerted by an individual gas in a mixture of gases. It's commonly used to describe the concentrations of gases in the body, such as oxygen (PO2), carbon dioxide (PCO2), and nitrogen (PN2).

The partial pressure of a specific gas is calculated as the fraction of that gas in the total mixture multiplied by the total pressure of the mixture. This concept is based on Dalton's law, which states that the total pressure exerted by a mixture of gases is equal to the sum of the pressures exerted by each individual gas.

For example, in room air at sea level, the partial pressure of oxygen (PO2) is approximately 160 mmHg (mm of mercury), which represents about 21% of the total barometric pressure (760 mmHg). This concept is crucial for understanding gas exchange in the lungs and how gases move across membranes, such as from alveoli to blood and vice versa.

Anoxia is a medical condition that refers to the absence or complete lack of oxygen supply in the body or a specific organ, tissue, or cell. This can lead to serious health consequences, including damage or death of cells and tissues, due to the vital role that oxygen plays in supporting cellular metabolism and energy production.

Anoxia can occur due to various reasons, such as respiratory failure, cardiac arrest, severe blood loss, carbon monoxide poisoning, or high altitude exposure. Prolonged anoxia can result in hypoxic-ischemic encephalopathy, a serious condition that can cause brain damage and long-term neurological impairments.

Medical professionals use various diagnostic tests, such as blood gas analysis, pulse oximetry, and electroencephalography (EEG), to assess oxygen levels in the body and diagnose anoxia. Treatment for anoxia typically involves addressing the underlying cause, providing supplemental oxygen, and supporting vital functions, such as breathing and circulation, to prevent further damage.

Hydrogen peroxide (H2O2) is a colorless, odorless, clear liquid with a slightly sweet taste, although drinking it is harmful and can cause poisoning. It is a weak oxidizing agent and is used as an antiseptic and a bleaching agent. In diluted form, it is used to disinfect wounds and kill bacteria and viruses on the skin; in higher concentrations, it can be used to bleach hair or remove stains from clothing. It is also used as a propellant in rocketry and in certain industrial processes. Chemically, hydrogen peroxide is composed of two hydrogen atoms and two oxygen atoms, and it is structurally similar to water (H2O), with an extra oxygen atom. This gives it its oxidizing properties, as the additional oxygen can be released and used to react with other substances.

Oxidation-Reduction (redox) reactions are a type of chemical reaction involving a transfer of electrons between two species. The substance that loses electrons in the reaction is oxidized, and the substance that gains electrons is reduced. Oxidation and reduction always occur together in a redox reaction, hence the term "oxidation-reduction."

In biological systems, redox reactions play a crucial role in many cellular processes, including energy production, metabolism, and signaling. The transfer of electrons in these reactions is often facilitated by specialized molecules called electron carriers, such as nicotinamide adenine dinucleotide (NAD+/NADH) and flavin adenine dinucleotide (FAD/FADH2).

The oxidation state of an element in a compound is a measure of the number of electrons that have been gained or lost relative to its neutral state. In redox reactions, the oxidation state of one or more elements changes as they gain or lose electrons. The substance that is oxidized has a higher oxidation state, while the substance that is reduced has a lower oxidation state.

Overall, oxidation-reduction reactions are fundamental to the functioning of living organisms and are involved in many important biological processes.

Oxidative stress is defined as an imbalance between the production of reactive oxygen species (free radicals) and the body's ability to detoxify them or repair the damage they cause. This imbalance can lead to cellular damage, oxidation of proteins, lipids, and DNA, disruption of cellular functions, and activation of inflammatory responses. Prolonged or excessive oxidative stress has been linked to various health conditions, including cancer, cardiovascular diseases, neurodegenerative disorders, and aging-related diseases.

Pulse oximetry is a noninvasive method for monitoring a person's oxygen saturation (SO2) and pulse rate. It uses a device called a pulse oximeter, which measures the amount of oxygen-carrying hemoglobin in the blood compared to the amount of hemoglobin that is not carrying oxygen. This measurement is expressed as a percentage, known as oxygen saturation (SpO2). Normal oxygen saturation levels are generally 95% or above at sea level. Lower levels may indicate hypoxemia, a condition where there is not enough oxygen in the blood to meet the body's needs. Pulse oximetry is commonly used in hospitals and other healthcare settings to monitor patients during surgery, in intensive care units, and in sleep studies to detect conditions such as sleep apnea. It can also be used by individuals with certain medical conditions, such as chronic obstructive pulmonary disease (COPD), to monitor their oxygen levels at home.

Antioxidants are substances that can prevent or slow damage to cells caused by free radicals, which are unstable molecules that the body produces as a reaction to environmental and other pressures. Antioxidants are able to neutralize free radicals by donating an electron to them, thus stabilizing them and preventing them from causing further damage to the cells.

Antioxidants can be found in a variety of foods, including fruits, vegetables, nuts, and grains. Some common antioxidants include vitamins C and E, beta-carotene, and selenium. Antioxidants are also available as dietary supplements.

In addition to their role in protecting cells from damage, antioxidants have been studied for their potential to prevent or treat a number of health conditions, including cancer, heart disease, and age-related macular degeneration. However, more research is needed to fully understand the potential benefits and risks of using antioxidant supplements.

Oxyhemoglobin is the form of hemoglobin that is combined with oxygen in red blood cells. It's created when oxygen molecules bind to the iron-containing heme groups of the hemoglobin protein inside the lungs, allowing for the transportation of oxygen from the lungs to body tissues. The affinity of hemoglobin for oxygen is influenced by factors such as pH, carbon dioxide concentration, and temperature, which can affect the release of oxygen from oxyhemoglobin in different parts of the body based on their specific needs.

Carbon dioxide (CO2) is a colorless, odorless gas that is naturally present in the Earth's atmosphere. It is a normal byproduct of cellular respiration in humans, animals, and plants, and is also produced through the combustion of fossil fuels such as coal, oil, and natural gas.

In medical terms, carbon dioxide is often used as a respiratory stimulant and to maintain the pH balance of blood. It is also used during certain medical procedures, such as laparoscopic surgery, to insufflate (inflate) the abdominal cavity and create a working space for the surgeon.

Elevated levels of carbon dioxide in the body can lead to respiratory acidosis, a condition characterized by an increased concentration of carbon dioxide in the blood and a decrease in pH. This can occur in conditions such as chronic obstructive pulmonary disease (COPD), asthma, or other lung diseases that impair breathing and gas exchange. Symptoms of respiratory acidosis may include shortness of breath, confusion, headache, and in severe cases, coma or death.

Aerobiosis is the process of living, growing, and functioning in the presence of oxygen. It refers to the metabolic processes that require oxygen to break down nutrients and produce energy in cells. This is in contrast to anaerobiosis, which is the ability to live and grow in the absence of oxygen.

In medical terms, aerobiosis is often used to describe the growth of microorganisms, such as bacteria and fungi, that require oxygen to survive and multiply. These organisms are called aerobic organisms, and they play an important role in many biological processes, including decomposition and waste breakdown.

However, some microorganisms are unable to grow in the presence of oxygen and are instead restricted to environments where oxygen is absent or limited. These organisms are called anaerobic organisms, and their growth and metabolism are referred to as anaerobiosis.

Medical Definition:

Superoxide dismutase (SOD) is an enzyme that catalyzes the dismutation of superoxide radicals (O2-) into oxygen (O2) and hydrogen peroxide (H2O2). This essential antioxidant defense mechanism helps protect the body's cells from damage caused by reactive oxygen species (ROS), which are produced during normal metabolic processes and can lead to oxidative stress when their levels become too high.

There are three main types of superoxide dismutase found in different cellular locations:
1. Copper-zinc superoxide dismutase (CuZnSOD or SOD1) - Present mainly in the cytoplasm of cells.
2. Manganese superoxide dismutase (MnSOD or SOD2) - Located within the mitochondrial matrix.
3. Extracellular superoxide dismutase (EcSOD or SOD3) - Found in the extracellular spaces, such as blood vessels and connective tissues.

Imbalances in SOD levels or activity have been linked to various pathological conditions, including neurodegenerative diseases, cancer, and aging-related disorders.

Hemoglobin (Hb or Hgb) is the main oxygen-carrying protein in the red blood cells, which are responsible for delivering oxygen throughout the body. It is a complex molecule made up of four globin proteins and four heme groups. Each heme group contains an iron atom that binds to one molecule of oxygen. Hemoglobin plays a crucial role in the transport of oxygen from the lungs to the body's tissues, and also helps to carry carbon dioxide back to the lungs for exhalation.

There are several types of hemoglobin present in the human body, including:

* Hemoglobin A (HbA): This is the most common type of hemoglobin, making up about 95-98% of total hemoglobin in adults. It consists of two alpha and two beta globin chains.
* Hemoglobin A2 (HbA2): This makes up about 1.5-3.5% of total hemoglobin in adults. It consists of two alpha and two delta globin chains.
* Hemoglobin F (HbF): This is the main type of hemoglobin present in fetal life, but it persists at low levels in adults. It consists of two alpha and two gamma globin chains.
* Hemoglobin S (HbS): This is an abnormal form of hemoglobin that can cause sickle cell disease when it occurs in the homozygous state (i.e., both copies of the gene are affected). It results from a single amino acid substitution in the beta globin chain.
* Hemoglobin C (HbC): This is another abnormal form of hemoglobin that can cause mild to moderate hemolytic anemia when it occurs in the homozygous state. It results from a different single amino acid substitution in the beta globin chain than HbS.

Abnormal forms of hemoglobin, such as HbS and HbC, can lead to various clinical disorders, including sickle cell disease, thalassemia, and other hemoglobinopathies.

Free radicals are molecules or atoms that have one or more unpaired electrons in their outermost shell, making them highly reactive. They can be formed naturally in the body through processes such as metabolism and exercise, or they can come from external sources like pollution, radiation, and certain chemicals. Free radicals can cause damage to cells and contribute to the development of various diseases, including cancer, cardiovascular disease, and neurodegenerative disorders. Antioxidants are substances that can neutralize free radicals and help protect against their harmful effects.

Free radical scavengers, also known as antioxidants, are substances that neutralize or stabilize free radicals. Free radicals are highly reactive atoms or molecules with unpaired electrons, capable of causing damage to cells and tissues in the body through a process called oxidative stress. Antioxidants donate an electron to the free radical, thereby neutralizing it and preventing it from causing further damage. They can be found naturally in foods such as fruits, vegetables, and nuts, or they can be synthesized and used as dietary supplements. Examples of antioxidants include vitamins C and E, beta-carotene, and selenium.

Mitochondria are specialized structures located inside cells that convert the energy from food into ATP (adenosine triphosphate), which is the primary form of energy used by cells. They are often referred to as the "powerhouses" of the cell because they generate most of the cell's supply of chemical energy. Mitochondria are also involved in various other cellular processes, such as signaling, differentiation, and apoptosis (programmed cell death).

Mitochondria have their own DNA, known as mitochondrial DNA (mtDNA), which is inherited maternally. This means that mtDNA is passed down from the mother to her offspring through the egg cells. Mitochondrial dysfunction has been linked to a variety of diseases and conditions, including neurodegenerative disorders, diabetes, and aging.

Catalase is a type of enzyme that is found in many living organisms, including humans. Its primary function is to catalyze the decomposition of hydrogen peroxide (H2O2) into water (H2O) and oxygen (O2). This reaction helps protect cells from the harmful effects of hydrogen peroxide, which can be toxic at high concentrations.

The chemical reaction catalyzed by catalase can be represented as follows:

H2O2 + Catalase → H2O + O2 + Catalase

Catalase is a powerful antioxidant enzyme that plays an important role in protecting cells from oxidative damage. It is found in high concentrations in tissues that produce or are exposed to hydrogen peroxide, such as the liver, kidneys, and erythrocytes (red blood cells).

Deficiency in catalase activity has been linked to several diseases, including cancer, neurodegenerative disorders, and aging. On the other hand, overexpression of catalase has been shown to have potential therapeutic benefits in various disease models, such as reducing inflammation and oxidative stress.

Hyperoxia is a medical term that refers to an abnormally high concentration of oxygen in the body or in a specific organ or tissue. It is often defined as the partial pressure of oxygen (PaO2) in arterial blood being greater than 100 mmHg.

This condition can occur due to various reasons such as exposure to high concentrations of oxygen during medical treatments, like mechanical ventilation, or due to certain diseases and conditions that cause the body to produce too much oxygen.

While oxygen is essential for human life, excessive levels can be harmful and lead to oxidative stress, which can damage cells and tissues. Hyperoxia has been linked to various complications, including lung injury, retinopathy of prematurity, and impaired wound healing.

NADPH oxidase is an enzyme complex that plays a crucial role in the production of reactive oxygen species (ROS) in various cell types. The primary function of NADPH oxidase is to catalyze the transfer of electrons from NADPH to molecular oxygen, resulting in the formation of superoxide radicals. This enzyme complex consists of several subunits, including two membrane-bound components (gp91phox and p22phox) and several cytosolic components (p47phox, p67phox, p40phox, and rac1 or rac2). Upon activation, these subunits assemble to form a functional enzyme complex that generates ROS, which serve as important signaling molecules in various cellular processes. However, excessive or uncontrolled production of ROS by NADPH oxidase has been implicated in the pathogenesis of several diseases, such as cardiovascular disorders, neurodegenerative diseases, and cancer.

Cell hypoxia, also known as cellular hypoxia or tissue hypoxia, refers to a condition in which the cells or tissues in the body do not receive an adequate supply of oxygen. Oxygen is essential for the production of energy in the form of ATP (adenosine triphosphate) through a process called oxidative phosphorylation. When the cells are deprived of oxygen, they switch to anaerobic metabolism, which produces lactic acid as a byproduct and can lead to acidosis.

Cell hypoxia can result from various conditions, including:

1. Low oxygen levels in the blood (hypoxemia) due to lung diseases such as chronic obstructive pulmonary disease (COPD), pneumonia, or high altitude.
2. Reduced blood flow to tissues due to cardiovascular diseases such as heart failure, peripheral artery disease, or shock.
3. Anemia, which reduces the oxygen-carrying capacity of the blood.
4. Carbon monoxide poisoning, which binds to hemoglobin and prevents it from carrying oxygen.
5. Inadequate ventilation due to trauma, drug overdose, or other causes that can lead to respiratory failure.

Cell hypoxia can cause cell damage, tissue injury, and organ dysfunction, leading to various clinical manifestations depending on the severity and duration of hypoxia. Treatment aims to correct the underlying cause and improve oxygen delivery to the tissues.

Anaerobiosis is a state in which an organism or a portion of an organism is able to live and grow in the absence of molecular oxygen (O2). In biological contexts, "anaerobe" refers to any organism that does not require oxygen for growth, and "aerobe" refers to an organism that does require oxygen for growth.

There are two types of anaerobes: obligate anaerobes, which cannot tolerate the presence of oxygen and will die if exposed to it; and facultative anaerobes, which can grow with or without oxygen but prefer to grow in its absence. Some organisms are able to switch between aerobic and anaerobic metabolism depending on the availability of oxygen, a process known as "facultative anaerobiosis."

Anaerobic respiration is a type of metabolic process that occurs in the absence of molecular oxygen. In this process, organisms use alternative electron acceptors other than oxygen to generate energy through the transfer of electrons during cellular respiration. Examples of alternative electron acceptors include nitrate, sulfate, and carbon dioxide.

Anaerobic metabolism is less efficient than aerobic metabolism in terms of energy production, but it allows organisms to survive in environments where oxygen is not available or is toxic. Anaerobic bacteria are important decomposers in many ecosystems, breaking down organic matter and releasing nutrients back into the environment. In the human body, anaerobic bacteria can cause infections and other health problems if they proliferate in areas with low oxygen levels, such as the mouth, intestines, or deep tissue wounds.

Superoxides are partially reduced derivatives of oxygen that contain one extra electron, giving them an overall charge of -1. They are highly reactive and unstable, with the most common superoxide being the hydroxyl radical (•OH-) and the superoxide anion (O2-). Superoxides are produced naturally in the body during metabolic processes, particularly within the mitochondria during cellular respiration. They play a role in various physiological processes, but when produced in excess or not properly neutralized, they can contribute to oxidative stress and damage to cells and tissues, potentially leading to the development of various diseases such as cancer, atherosclerosis, and neurodegenerative disorders.

Blood gas analysis is a medical test that measures the levels of oxygen and carbon dioxide in the blood, as well as the pH level, which indicates the acidity or alkalinity of the blood. This test is often used to evaluate lung function, respiratory disorders, and acid-base balance in the body. It can also be used to monitor the effectiveness of treatments for conditions such as chronic obstructive pulmonary disease (COPD), asthma, and other respiratory illnesses. The analysis is typically performed on a sample of arterial blood, although venous blood may also be used in some cases.

Polarography is a type of electrochemical analysis technique used to determine the concentration of an ion or electron-transferring species in a solution. It involves measuring the current that flows through an electrode as the voltage is varied, which can provide information about the redox potential and the number of electrons transferred during a reaction. The technique is particularly useful for analyzing complex mixtures and for detecting trace amounts of substances.

In polarography, a dropping mercury electrode (DME) is typically used as the working electrode. As the mercury droplets fall from the electrode, they create fresh surfaces for analysis, which helps to minimize interference from surface-adsorbed species. The DME is immersed in a solution containing the analyte along with a supporting electrolyte, and a potential is applied between the DME and a reference electrode.

As the potential is scanned, reduction or oxidation of the analyte occurs at the DME surface, leading to a current that can be measured. The resulting polarogram (a plot of current vs. voltage) shows peaks or waves corresponding to the redox potentials of the analyte, which can be used to identify and quantify the species present in the solution.

Polarography is a sensitive and selective technique that has been widely used in fields such as environmental analysis, pharmaceuticals, and biochemistry. However, it has largely been replaced by more modern electrochemical techniques, such as cyclic voltammetry and differential pulse voltammetry, which offer higher sensitivity and better resolution of complex mixtures.

In the field of medicine, "time factors" refer to the duration of symptoms or time elapsed since the onset of a medical condition, which can have significant implications for diagnosis and treatment. Understanding time factors is crucial in determining the progression of a disease, evaluating the effectiveness of treatments, and making critical decisions regarding patient care.

For example, in stroke management, "time is brain," meaning that rapid intervention within a specific time frame (usually within 4.5 hours) is essential to administering tissue plasminogen activator (tPA), a clot-busting drug that can minimize brain damage and improve patient outcomes. Similarly, in trauma care, the "golden hour" concept emphasizes the importance of providing definitive care within the first 60 minutes after injury to increase survival rates and reduce morbidity.

Time factors also play a role in monitoring the progression of chronic conditions like diabetes or heart disease, where regular follow-ups and assessments help determine appropriate treatment adjustments and prevent complications. In infectious diseases, time factors are crucial for initiating antibiotic therapy and identifying potential outbreaks to control their spread.

Overall, "time factors" encompass the significance of recognizing and acting promptly in various medical scenarios to optimize patient outcomes and provide effective care.

Luminescent measurements refer to the quantitative assessment of the emission of light from a substance that has been excited, typically through some form of energy input such as electrical energy or radiation. In the context of medical diagnostics and research, luminescent measurements can be used in various applications, including bioluminescence imaging, which is used to study biological processes at the cellular and molecular level.

Bioluminescence occurs when a chemical reaction produces light within a living organism, often through the action of enzymes such as luciferase. By introducing a luciferase gene into cells or organisms, researchers can use bioluminescent measurements to track cellular processes and monitor gene expression in real time.

Luminescent measurements may also be used in medical research to study the properties of materials used in medical devices, such as LEDs or optical fibers, or to develop new diagnostic tools based on light-emitting nanoparticles or other luminescent materials.

In summary, luminescent measurements are a valuable tool in medical research and diagnostics, providing a non-invasive way to study biological processes and develop new technologies for disease detection and treatment.

In the context of medicine and pharmacology, "kinetics" refers to the study of how a drug moves throughout the body, including its absorption, distribution, metabolism, and excretion (often abbreviated as ADME). This field is called "pharmacokinetics."

1. Absorption: This is the process of a drug moving from its site of administration into the bloodstream. Factors such as the route of administration (e.g., oral, intravenous, etc.), formulation, and individual physiological differences can affect absorption.

2. Distribution: Once a drug is in the bloodstream, it gets distributed throughout the body to various tissues and organs. This process is influenced by factors like blood flow, protein binding, and lipid solubility of the drug.

3. Metabolism: Drugs are often chemically modified in the body, typically in the liver, through processes known as metabolism. These changes can lead to the formation of active or inactive metabolites, which may then be further distributed, excreted, or undergo additional metabolic transformations.

4. Excretion: This is the process by which drugs and their metabolites are eliminated from the body, primarily through the kidneys (urine) and the liver (bile).

Understanding the kinetics of a drug is crucial for determining its optimal dosing regimen, potential interactions with other medications or foods, and any necessary adjustments for special populations like pediatric or geriatric patients, or those with impaired renal or hepatic function.

Pulmonary gas exchange is the process by which oxygen (O2) from inhaled air is transferred to the blood, and carbon dioxide (CO2), a waste product of metabolism, is removed from the blood and exhaled. This process occurs in the lungs, primarily in the alveoli, where the thin walls of the alveoli and capillaries allow for the rapid diffusion of gases between them. The partial pressure gradient between the alveolar air and the blood in the pulmonary capillaries drives this diffusion process. Oxygen-rich blood is then transported to the body's tissues, while CO2-rich blood returns to the lungs to be exhaled.

Energy metabolism is the process by which living organisms produce and consume energy to maintain life. It involves a series of chemical reactions that convert nutrients from food, such as carbohydrates, fats, and proteins, into energy in the form of adenosine triphosphate (ATP).

The process of energy metabolism can be divided into two main categories: catabolism and anabolism. Catabolism is the breakdown of nutrients to release energy, while anabolism is the synthesis of complex molecules from simpler ones using energy.

There are three main stages of energy metabolism: glycolysis, the citric acid cycle (also known as the Krebs cycle), and oxidative phosphorylation. Glycolysis occurs in the cytoplasm of the cell and involves the breakdown of glucose into pyruvate, producing a small amount of ATP and nicotinamide adenine dinucleotide (NADH). The citric acid cycle takes place in the mitochondria and involves the further breakdown of pyruvate to produce more ATP, NADH, and carbon dioxide. Oxidative phosphorylation is the final stage of energy metabolism and occurs in the inner mitochondrial membrane. It involves the transfer of electrons from NADH and other electron carriers to oxygen, which generates a proton gradient across the membrane. This gradient drives the synthesis of ATP, producing the majority of the cell's energy.

Overall, energy metabolism is a complex and essential process that allows organisms to grow, reproduce, and maintain their bodily functions. Disruptions in energy metabolism can lead to various diseases, including diabetes, obesity, and neurodegenerative disorders.

Blood substitutes, also known as artificial blood or blood surrogates, are fluids that are designed to mimic some of the properties and functions of human blood. They are used as a replacement for blood transfusions in situations where blood is not available or when it is not safe to use. Blood substitutes can be divided into two main categories: oxygen-carrying and non-oxygen-carrying.

Oxygen-carrying blood substitutes contain artificial molecules called hemoglobin-based oxygen carriers (HBOCs) that are designed to carry oxygen from the lungs to the body's tissues. These HBOCs can be derived from human or animal hemoglobin, or they can be synthetically produced.

Non-oxygen-carrying blood substitutes, on the other hand, do not contain hemoglobin and are used primarily to restore intravascular volume and maintain blood pressure in cases of hypovolemia (low blood volume) caused by bleeding or dehydration. These products include crystalloids, such as saline solution and lactated Ringer's solution, and colloids, such as albumin and hydroxyethyl starch solutions.

It is important to note that while blood substitutes can be useful in certain situations, they are not a perfect substitute for human blood. They do not provide all of the functions of blood, such as immune defense and clotting, and their use is associated with some risks, including allergic reactions, kidney damage, and increased oxygen free radical production. Therefore, they should only be used when there is no suitable alternative available.

Medical Definition of Respiration:

Respiration, in physiology, is the process by which an organism takes in oxygen and gives out carbon dioxide. It's also known as breathing. This process is essential for most forms of life because it provides the necessary oxygen for cellular respiration, where the cells convert biochemical energy from nutrients into adenosine triphosphate (ATP), and releases waste products, primarily carbon dioxide.

In humans and other mammals, respiration is a two-stage process:

1. Breathing (or external respiration): This involves the exchange of gases with the environment. Air enters the lungs through the mouth or nose, then passes through the pharynx, larynx, trachea, and bronchi, finally reaching the alveoli where the actual gas exchange occurs. Oxygen from the inhaled air diffuses into the blood, while carbon dioxide, a waste product of metabolism, diffuses from the blood into the alveoli to be exhaled.

2. Cellular respiration (or internal respiration): This is the process by which cells convert glucose and other nutrients into ATP, water, and carbon dioxide in the presence of oxygen. The carbon dioxide produced during this process then diffuses out of the cells and into the bloodstream to be exhaled during breathing.

In summary, respiration is a vital physiological function that enables organisms to obtain the necessary oxygen for cellular metabolism while eliminating waste products like carbon dioxide.

Transcutaneous blood gas monitoring (TcBGM) is a non-invasive method to measure the partial pressure of oxygen (pO2) and carbon dioxide (pCO2) in the blood. This technique uses heated sensors placed on the skin, typically on the ear lobe or the soles of the feet, to estimate the gas tensions in the capillary blood.

The sensors contain a electrochemical or optical sensor that measures the pO2 and pCO2 levels in the tiny amount of gas that diffuses through the skin from the underlying capillaries. The measurements are then adjusted to reflect the actual blood gas values based on calibration curves and other factors, such as the patient's age, temperature, and skin perfusion.

TcBGM is commonly used in neonatal intensive care units (NICUs) to monitor oxygenation and ventilation in premature infants, who may have immature lungs or other respiratory problems that make invasive blood gas sampling difficult or risky. It can also be used in adults with conditions such as chronic obstructive pulmonary disease (COPD), sleep apnea, or neuromuscular disorders, where frequent blood gas measurements are needed to guide therapy and monitor response to treatment.

Overall, TcBGM provides a safe, painless, and convenient way to monitor blood gases in real-time, without the need for repeated arterial punctures or other invasive procedures. However, it is important to note that TcBGM may not always provide accurate measurements in certain situations, such as when the skin perfusion is poor or when there are significant differences between the capillary and arterial blood gases. Therefore, clinical judgment and other diagnostic tests should be used in conjunction with TcBGM to ensure appropriate patient management.

Medical definitions of "oxidants" refer to them as oxidizing agents or substances that can gain electrons and be reduced. They are capable of accepting electrons from other molecules in chemical reactions, leading to the production of oxidation products. In biological systems, oxidants play a crucial role in various cellular processes such as energy production and immune responses. However, an imbalance between oxidant and antioxidant levels can lead to a state of oxidative stress, which has been linked to several diseases, including cancer, cardiovascular disease, and neurodegenerative disorders. Examples of oxidants include reactive oxygen species (ROS), such as superoxide anion, hydrogen peroxide, and hydroxyl radical, as well as reactive nitrogen species (RNS), such as nitric oxide and peroxynitrite.

"Cells, cultured" is a medical term that refers to cells that have been removed from an organism and grown in controlled laboratory conditions outside of the body. This process is called cell culture and it allows scientists to study cells in a more controlled and accessible environment than they would have inside the body. Cultured cells can be derived from a variety of sources, including tissues, organs, or fluids from humans, animals, or cell lines that have been previously established in the laboratory.

Cell culture involves several steps, including isolation of the cells from the tissue, purification and characterization of the cells, and maintenance of the cells in appropriate growth conditions. The cells are typically grown in specialized media that contain nutrients, growth factors, and other components necessary for their survival and proliferation. Cultured cells can be used for a variety of purposes, including basic research, drug development and testing, and production of biological products such as vaccines and gene therapies.

It is important to note that cultured cells may behave differently than they do in the body, and results obtained from cell culture studies may not always translate directly to human physiology or disease. Therefore, it is essential to validate findings from cell culture experiments using additional models and ultimately in clinical trials involving human subjects.

Oxygen radioisotopes are unstable isotopes of the element oxygen that emit radiation as they decay to a more stable form. These isotopes can be used in medical imaging and treatment, such as positron emission tomography (PET) scans. Common oxygen radioisotopes used in medicine include oxygen-15 and oxygen-18. Oxygen-15 has a very short half-life of about 2 minutes, while oxygen-18 has a longer half-life of about 2 hours. These isotopes can be incorporated into molecules such as water or carbon dioxide, which can then be used to study blood flow, metabolism and other physiological processes in the body.

Xanthine oxidase is an enzyme that catalyzes the oxidation of xanthine to uric acid, which is the last step in purine metabolism. It's a type of molybdenum-containing oxidoreductase that generates reactive oxygen species (ROS) during its reaction mechanism.

The enzyme exists in two interconvertible forms: an oxidized state and a reduced state. The oxidized form, called xanthine oxidase, reduces molecular oxygen to superoxide and hydrogen peroxide, while the reduced form, called xanthine dehydrogenase, reduces NAD+ to NADH.

Xanthine oxidase is found in various tissues, including the liver, intestines, and milk. An overproduction of uric acid due to increased activity of xanthine oxidase can lead to hyperuricemia, which may result in gout or kidney stones. Some medications and natural compounds are known to inhibit xanthine oxidase, such as allopurinol and febuxostat, which are used to treat gout and prevent the formation of uric acid stones in the kidneys.

Nitric oxide (NO) is a molecule made up of one nitrogen atom and one oxygen atom. In the body, it is a crucial signaling molecule involved in various physiological processes such as vasodilation, immune response, neurotransmission, and inhibition of platelet aggregation. It is produced naturally by the enzyme nitric oxide synthase (NOS) from the amino acid L-arginine. Inhaled nitric oxide is used medically to treat pulmonary hypertension in newborns and adults, as it helps to relax and widen blood vessels, improving oxygenation and blood flow.

Reactive Nitrogen Species (RNS) are a group of highly reactive and chemically diverse molecules that are derived from nitric oxide (NO) or other nitrogen-containing compounds. They play important roles in various biological processes, such as cell signaling, neurotransmission, and immune response. However, an overproduction of RNS can also contribute to the development of several pathological conditions, including inflammation, neurodegenerative diseases, and cancer. Examples of RNS include nitric oxide (NO), peroxynitrite (ONOO-), and nitrogen dioxide (NO2). These species are generated through various biochemical reactions, such as the conversion of L-arginine to citrulline by nitric oxide synthase (NOS) enzymes, which leads to the production of NO. RNS can then react with other molecules in the body, such as reactive oxygen species (ROS), leading to the formation of harmful compounds that can damage cellular structures and disrupt normal physiological functions.

Acetylcysteine is a medication that is used for its antioxidant effects and to help loosen thick mucus in the lungs. It is commonly used to treat conditions such as chronic bronchitis, emphysema, and cystic fibrosis. Acetylcysteine is also known by the brand names Mucomyst and Accolate. It works by thinning and breaking down mucus in the airways, making it easier to cough up and clear the airways. Additionally, acetylcysteine is an antioxidant that helps to protect cells from damage caused by free radicals. It is available as a oral tablet, liquid, or inhaled medication.

Glutathione is a tripeptide composed of three amino acids: cysteine, glutamic acid, and glycine. It is a vital antioxidant that plays an essential role in maintaining cellular health and function. Glutathione helps protect cells from oxidative stress by neutralizing free radicals, which are unstable molecules that can damage cells and contribute to aging and diseases such as cancer, heart disease, and dementia. It also supports the immune system, detoxifies harmful substances, and regulates various cellular processes, including DNA synthesis and repair.

Glutathione is found in every cell of the body, with particularly high concentrations in the liver, lungs, and eyes. The body can produce its own glutathione, but levels may decline with age, illness, or exposure to toxins. As such, maintaining optimal glutathione levels through diet, supplementation, or other means is essential for overall health and well-being.

Hydrogen-ion concentration, also known as pH, is a measure of the acidity or basicity of a solution. It is defined as the negative logarithm (to the base 10) of the hydrogen ion activity in a solution. The standard unit of measurement is the pH unit. A pH of 7 is neutral, less than 7 is acidic, and greater than 7 is basic.

In medical terms, hydrogen-ion concentration is important for maintaining homeostasis within the body. For example, in the stomach, a high hydrogen-ion concentration (low pH) is necessary for the digestion of food. However, in other parts of the body such as blood, a high hydrogen-ion concentration can be harmful and lead to acidosis. Conversely, a low hydrogen-ion concentration (high pH) in the blood can lead to alkalosis. Both acidosis and alkalosis can have serious consequences on various organ systems if not corrected.

Biological models, also known as physiological models or organismal models, are simplified representations of biological systems, processes, or mechanisms that are used to understand and explain the underlying principles and relationships. These models can be theoretical (conceptual or mathematical) or physical (such as anatomical models, cell cultures, or animal models). They are widely used in biomedical research to study various phenomena, including disease pathophysiology, drug action, and therapeutic interventions.

Examples of biological models include:

1. Mathematical models: These use mathematical equations and formulas to describe complex biological systems or processes, such as population dynamics, metabolic pathways, or gene regulation networks. They can help predict the behavior of these systems under different conditions and test hypotheses about their underlying mechanisms.
2. Cell cultures: These are collections of cells grown in a controlled environment, typically in a laboratory dish or flask. They can be used to study cellular processes, such as signal transduction, gene expression, or metabolism, and to test the effects of drugs or other treatments on these processes.
3. Animal models: These are living organisms, usually vertebrates like mice, rats, or non-human primates, that are used to study various aspects of human biology and disease. They can provide valuable insights into the pathophysiology of diseases, the mechanisms of drug action, and the safety and efficacy of new therapies.
4. Anatomical models: These are physical representations of biological structures or systems, such as plastic models of organs or tissues, that can be used for educational purposes or to plan surgical procedures. They can also serve as a basis for developing more sophisticated models, such as computer simulations or 3D-printed replicas.

Overall, biological models play a crucial role in advancing our understanding of biology and medicine, helping to identify new targets for therapeutic intervention, develop novel drugs and treatments, and improve human health.

An exercise test, also known as a stress test or an exercise stress test, is a medical procedure used to evaluate the heart's function and response to physical exertion. It typically involves walking on a treadmill or pedaling a stationary bike while being monitored for changes in heart rate, blood pressure, electrocardiogram (ECG), and sometimes other variables such as oxygen consumption or gas exchange.

During the test, the patient's symptoms, such as chest pain or shortness of breath, are also closely monitored. The exercise test can help diagnose coronary artery disease, assess the severity of heart-related symptoms, and evaluate the effectiveness of treatments for heart conditions. It may also be used to determine a person's safe level of physical activity and fitness.

There are different types of exercise tests, including treadmill stress testing, stationary bike stress testing, nuclear stress testing, and stress echocardiography. The specific type of test used depends on the patient's medical history, symptoms, and overall health status.

Hemodynamics is the study of how blood flows through the cardiovascular system, including the heart and the vascular network. It examines various factors that affect blood flow, such as blood volume, viscosity, vessel length and diameter, and pressure differences between different parts of the circulatory system. Hemodynamics also considers the impact of various physiological and pathological conditions on these variables, and how they in turn influence the function of vital organs and systems in the body. It is a critical area of study in fields such as cardiology, anesthesiology, and critical care medicine.

The Electron Transport Chain (ETC) is a series of complexes in the inner mitochondrial membrane that are involved in the process of cellular respiration. It is the final pathway for electrons derived from the oxidation of nutrients such as glucose, fatty acids, and amino acids to be transferred to molecular oxygen. This transfer of electrons drives the generation of a proton gradient across the inner mitochondrial membrane, which is then used by ATP synthase to produce ATP, the main energy currency of the cell.

The electron transport chain consists of four complexes (I-IV) and two mobile electron carriers (ubiquinone and cytochrome c). Electrons from NADH and FADH2 are transferred to Complex I and Complex II respectively, which then pass them along to ubiquinone. Ubiquinone then transfers the electrons to Complex III, which passes them on to cytochrome c. Finally, cytochrome c transfers the electrons to Complex IV, where they combine with oxygen and protons to form water.

The transfer of electrons through the ETC is accompanied by the pumping of protons from the mitochondrial matrix to the intermembrane space, creating a proton gradient. The flow of protons back across the inner membrane through ATP synthase drives the synthesis of ATP from ADP and inorganic phosphate.

Overall, the electron transport chain is a crucial process for generating energy in the form of ATP in the cell, and it plays a key role in many metabolic pathways.

Apoptosis is a programmed and controlled cell death process that occurs in multicellular organisms. It is a natural process that helps maintain tissue homeostasis by eliminating damaged, infected, or unwanted cells. During apoptosis, the cell undergoes a series of morphological changes, including cell shrinkage, chromatin condensation, and fragmentation into membrane-bound vesicles called apoptotic bodies. These bodies are then recognized and engulfed by neighboring cells or phagocytic cells, preventing an inflammatory response. Apoptosis is regulated by a complex network of intracellular signaling pathways that involve proteins such as caspases, Bcl-2 family members, and inhibitors of apoptosis (IAPs).

Electron Spin Resonance (ESR) Spectroscopy, also known as Electron Paramagnetic Resonance (EPR) Spectroscopy, is a technique used to investigate materials with unpaired electrons. It is based on the principle of absorption of energy by the unpaired electrons when they are exposed to an external magnetic field and microwave radiation.

In this technique, a sample is placed in a magnetic field and microwave radiation is applied. The unpaired electrons in the sample absorb energy and change their spin state when the energy of the microwaves matches the energy difference between the spin states. This absorption of energy is recorded as a function of the magnetic field strength, producing an ESR spectrum.

ESR spectroscopy can provide information about the number, type, and behavior of unpaired electrons in a sample, as well as the local environment around the electron. It is widely used in physics, chemistry, and biology to study materials such as free radicals, transition metal ions, and defects in solids.

Hypoxia-Inducible Factor 1 (HIF-1) is a transcription factor that plays a crucial role in the body's response to low oxygen levels, also known as hypoxia. HIF-1 is a heterodimeric protein composed of two subunits: an alpha subunit (HIF-1α) and a beta subunit (HIF-1β).

The alpha subunit, HIF-1α, is the regulatory subunit that is subject to oxygen-dependent degradation. Under normal oxygen conditions (normoxia), HIF-1α is constantly produced in the cell but is rapidly degraded by proteasomes due to hydroxylation of specific proline residues by prolyl hydroxylase domain-containing proteins (PHDs). This hydroxylation reaction requires oxygen as a substrate, and under hypoxic conditions, the activity of PHDs is inhibited, leading to the stabilization and accumulation of HIF-1α.

Once stabilized, HIF-1α translocates to the nucleus, where it heterodimerizes with HIF-1β and binds to hypoxia-responsive elements (HREs) in the promoter regions of target genes. This binding results in the activation of gene transcription programs that promote cellular adaptation to low oxygen levels. These adaptive responses include increased erythropoiesis, angiogenesis, glucose metabolism, and pH regulation, among others.

Therefore, HIF-1α is a critical regulator of the body's response to hypoxia, and its dysregulation has been implicated in various pathological conditions, including cancer, cardiovascular disease, and neurodegenerative disorders.

Diphosphoglycerates (also known as 2,3-diphosphoglycerates or 2,3-DPG) are organic molecules found in red blood cells. They play a crucial role in regulating the affinity of hemoglobin for oxygen. Hemoglobin is the protein in red blood cells that carries oxygen from the lungs to the body's tissues.

When the concentration of diphosphoglycerates in red blood cells increases, it reduces the ability of hemoglobin to bind with oxygen, which allows more oxygen to be released into the tissues. This is particularly important in conditions where there is low oxygen availability, such as at high altitudes or in diseases that cause poor oxygen delivery to the tissues, like heart failure and chronic obstructive pulmonary disease (COPD).

In summary, diphosphoglycerates are essential molecules that help regulate hemoglobin's affinity for oxygen, ensuring optimal oxygen delivery to the body's tissues.

A hydroxyl radical is defined in biochemistry and medicine as an extremely reactive species, characterized by the presence of an oxygen atom bonded to a hydrogen atom (OH-). It is formed when a water molecule (H2O) is split into a hydroxide ion (OH-) and a hydrogen ion (H+) in the process of oxidation.

In medical terms, hydroxyl radicals are important in understanding free radical damage and oxidative stress, which can contribute to the development of various diseases, including cancer, cardiovascular disease, and neurodegenerative disorders. They are also involved in the body's natural defense mechanisms against pathogens. However, an overproduction of hydroxyl radicals can cause damage to cellular components such as DNA, proteins, and lipids, leading to cell dysfunction and death.

Signal transduction is the process by which a cell converts an extracellular signal, such as a hormone or neurotransmitter, into an intracellular response. This involves a series of molecular events that transmit the signal from the cell surface to the interior of the cell, ultimately resulting in changes in gene expression, protein activity, or metabolism.

The process typically begins with the binding of the extracellular signal to a receptor located on the cell membrane. This binding event activates the receptor, which then triggers a cascade of intracellular signaling molecules, such as second messengers, protein kinases, and ion channels. These molecules amplify and propagate the signal, ultimately leading to the activation or inhibition of specific cellular responses.

Signal transduction pathways are highly regulated and can be modulated by various factors, including other signaling molecules, post-translational modifications, and feedback mechanisms. Dysregulation of these pathways has been implicated in a variety of diseases, including cancer, diabetes, and neurological disorders.

Glucose is a simple monosaccharide (or single sugar) that serves as the primary source of energy for living organisms. It's a fundamental molecule in biology, often referred to as "dextrose" or "grape sugar." Glucose has the molecular formula C6H12O6 and is vital to the functioning of cells, especially those in the brain and nervous system.

In the body, glucose is derived from the digestion of carbohydrates in food, and it's transported around the body via the bloodstream to cells where it can be used for energy. Cells convert glucose into a usable form through a process called cellular respiration, which involves a series of metabolic reactions that generate adenosine triphosphate (ATP)—the main currency of energy in cells.

Glucose is also stored in the liver and muscles as glycogen, a polysaccharide (multiple sugar) that can be broken down back into glucose when needed for energy between meals or during physical activity. Maintaining appropriate blood glucose levels is crucial for overall health, and imbalances can lead to conditions such as diabetes mellitus.

Lactic acid, also known as 2-hydroxypropanoic acid, is a chemical compound that plays a significant role in various biological processes. In the context of medicine and biochemistry, lactic acid is primarily discussed in relation to muscle metabolism and cellular energy production. Here's a medical definition for lactic acid:

Lactic acid (LA): A carboxylic acid with the molecular formula C3H6O3 that plays a crucial role in anaerobic respiration, particularly during strenuous exercise or conditions of reduced oxygen availability. It is formed through the conversion of pyruvate, catalyzed by the enzyme lactate dehydrogenase (LDH), when there is insufficient oxygen to complete the final step of cellular respiration in the Krebs cycle. The accumulation of lactic acid can lead to acidosis and muscle fatigue. Additionally, lactic acid serves as a vital intermediary in various metabolic pathways and is involved in the production of glucose through gluconeogenesis in the liver.

Heart rate is the number of heartbeats per unit of time, often expressed as beats per minute (bpm). It can vary significantly depending on factors such as age, physical fitness, emotions, and overall health status. A resting heart rate between 60-100 bpm is generally considered normal for adults, but athletes and individuals with high levels of physical fitness may have a resting heart rate below 60 bpm due to their enhanced cardiovascular efficiency. Monitoring heart rate can provide valuable insights into an individual's health status, exercise intensity, and response to various treatments or interventions.

Lipid peroxidation is a process in which free radicals, such as reactive oxygen species (ROS), steal electrons from lipids containing carbon-carbon double bonds, particularly polyunsaturated fatty acids (PUFAs). This results in the formation of lipid hydroperoxides, which can decompose to form a variety of compounds including reactive carbonyl compounds, aldehydes, and ketones.

Malondialdehyde (MDA) is one such compound that is commonly used as a marker for lipid peroxidation. Lipid peroxidation can cause damage to cell membranes, leading to changes in their fluidity and permeability, and can also result in the modification of proteins and DNA, contributing to cellular dysfunction and ultimately cell death. It is associated with various pathological conditions such as atherosclerosis, neurodegenerative diseases, and cancer.

Electron Transport Complex IV is also known as Cytochrome c oxidase. It is the last complex in the electron transport chain, located in the inner mitochondrial membrane of eukaryotic cells and the plasma membrane of prokaryotic cells. This complex contains 13 subunits, two heme groups (a and a3), and three copper centers (A, B, and C).

In the electron transport chain, Complex IV receives electrons from cytochrome c and transfers them to molecular oxygen, reducing it to water. This process is accompanied by the pumping of protons across the membrane, contributing to the generation of a proton gradient that drives ATP synthesis via ATP synthase (Complex V). The overall reaction catalyzed by Complex IV can be summarized as follows:

4e- + 4H+ + O2 → 2H2O

Defects in Cytochrome c oxidase can lead to various diseases, including mitochondrial encephalomyopathies and neurodegenerative disorders.

Ion-Selective Electrodes (ISEs) are a type of chemical sensor that measure the activity of specific ions in a solution. They work by converting the chemical response into an electrical signal, which can then be measured and analyzed. The electrode is coated with a membrane that is selectively permeable to a particular ion, allowing for the detection and measurement of that specific ion in the presence of other ions.

ISEs are widely used in various fields such as clinical chemistry, biomedical research, environmental monitoring, and industrial process control. In medical diagnostics, ISEs are commonly used to measure the levels of ions such as sodium, potassium, chloride, and calcium in biological samples like blood, urine, and cerebrospinal fluid.

The response of an ISE is based on Nernst's equation, which relates the electrical potential across the membrane to the activity of the ion being measured. The selectivity of the electrode for a particular ion is determined by the type of membrane used, and the choice of membrane depends on the application and the specific ions to be measured.

Overall, Ion-Selective Electrodes are important tools in medical diagnostics and research, providing accurate and reliable measurements of ion activity in biological systems.

Sprague-Dawley rats are a strain of albino laboratory rats that are widely used in scientific research. They were first developed by researchers H.H. Sprague and R.C. Dawley in the early 20th century, and have since become one of the most commonly used rat strains in biomedical research due to their relatively large size, ease of handling, and consistent genetic background.

Sprague-Dawley rats are outbred, which means that they are genetically diverse and do not suffer from the same limitations as inbred strains, which can have reduced fertility and increased susceptibility to certain diseases. They are also characterized by their docile nature and low levels of aggression, making them easier to handle and study than some other rat strains.

These rats are used in a wide variety of research areas, including toxicology, pharmacology, nutrition, cancer, and behavioral studies. Because they are genetically diverse, Sprague-Dawley rats can be used to model a range of human diseases and conditions, making them an important tool in the development of new drugs and therapies.

Cerebrovascular circulation refers to the network of blood vessels that supply oxygenated blood and nutrients to the brain tissue, and remove waste products. It includes the internal carotid arteries, vertebral arteries, circle of Willis, and the intracranial arteries that branch off from them.

The internal carotid arteries and vertebral arteries merge to form the circle of Willis, a polygonal network of vessels located at the base of the brain. The anterior cerebral artery, middle cerebral artery, posterior cerebral artery, and communicating arteries are the major vessels that branch off from the circle of Willis and supply blood to different regions of the brain.

Interruptions or abnormalities in the cerebrovascular circulation can lead to various neurological conditions such as stroke, transient ischemic attack (TIA), and vascular dementia.

Physical exertion is defined as the act of applying energy to physically demandable activities or tasks, which results in various body systems working together to produce movement and maintain homeostasis. It often leads to an increase in heart rate, respiratory rate, and body temperature, among other physiological responses. The level of physical exertion can vary based on the intensity, duration, and frequency of the activity.

It's important to note that engaging in regular physical exertion has numerous health benefits, such as improving cardiovascular fitness, strengthening muscles and bones, reducing stress, and preventing chronic diseases like obesity, diabetes, and heart disease. However, it is also crucial to balance physical exertion with adequate rest and recovery time to avoid overtraining or injury.

Oxidoreductases are a class of enzymes that catalyze oxidation-reduction reactions, which involve the transfer of electrons from one molecule (the reductant) to another (the oxidant). These enzymes play a crucial role in various biological processes, including energy production, metabolism, and detoxification.

The oxidoreductase-catalyzed reaction typically involves the donation of electrons from a reducing agent (donor) to an oxidizing agent (acceptor), often through the transfer of hydrogen atoms or hydride ions. The enzyme itself does not undergo any permanent chemical change during this process, but rather acts as a catalyst to lower the activation energy required for the reaction to occur.

Oxidoreductases are classified and named based on the type of electron donor or acceptor involved in the reaction. For example, oxidoreductases that act on the CH-OH group of donors are called dehydrogenases, while those that act on the aldehyde or ketone groups are called oxidases. Other examples include reductases, peroxidases, and catalases.

Understanding the function and regulation of oxidoreductases is important for understanding various physiological processes and developing therapeutic strategies for diseases associated with impaired redox homeostasis, such as cancer, neurodegenerative disorders, and cardiovascular disease.

Carbon monoxide (CO) is a colorless, odorless, and tasteless gas that is slightly less dense than air. It is toxic to hemoglobic animals when encountered in concentrations above about 35 ppm. This compound is a product of incomplete combustion of organic matter, and is a major component of automobile exhaust.

Carbon monoxide is poisonous because it binds to hemoglobin in red blood cells much more strongly than oxygen does, forming carboxyhemoglobin. This prevents the transport of oxygen throughout the body, which can lead to suffocation and death. Symptoms of carbon monoxide poisoning include headache, dizziness, weakness, nausea, vomiting, confusion, and disorientation. Prolonged exposure can lead to unconsciousness and death.

Carbon monoxide detectors are commonly used in homes and other buildings to alert occupants to the presence of this dangerous gas. It is important to ensure that these devices are functioning properly and that they are placed in appropriate locations throughout the building. Additionally, it is essential to maintain appliances and heating systems to prevent the release of carbon monoxide into living spaces.

Cell survival refers to the ability of a cell to continue living and functioning normally, despite being exposed to potentially harmful conditions or treatments. This can include exposure to toxins, radiation, chemotherapeutic drugs, or other stressors that can damage cells or interfere with their normal processes.

In scientific research, measures of cell survival are often used to evaluate the effectiveness of various therapies or treatments. For example, researchers may expose cells to a particular drug or treatment and then measure the percentage of cells that survive to assess its potential therapeutic value. Similarly, in toxicology studies, measures of cell survival can help to determine the safety of various chemicals or substances.

It's important to note that cell survival is not the same as cell proliferation, which refers to the ability of cells to divide and multiply. While some treatments may promote cell survival, they may also inhibit cell proliferation, making them useful for treating diseases such as cancer. Conversely, other treatments may be designed to specifically target and kill cancer cells, even if it means sacrificing some healthy cells in the process.

Mitochondrial membrane potential is the electric potential difference (voltage) across the inner mitochondrial membrane. It is negative inside the mitochondria and positive outside. This electrical gradient is established by the active transport of hydrogen ions (protons) out of the mitochondrial matrix and into the intermembrane space by complexes in the electron transport chain during oxidative phosphorylation. The energy stored in this electrochemical gradient is used to generate ATP, which is the main source of energy for cellular metabolism.

Cyclic N-oxides are a class of organic compounds that contain a cyclic structure with a nitrogen atom bonded to an oxygen atom as an N-oxide. An N-oxide is a compound in which the nitrogen atom has a positive charge and the oxygen atom has a negative charge, forming a polar covalent bond. In cyclic N-oxides, this N-O group is part of a ring structure, which can be composed of various combinations of carbon, nitrogen, and other atoms. These compounds have been studied for their potential use in pharmaceuticals, agrochemicals, and materials science.

In medical terms, 'air' is defined as the mixture of gases that make up the Earth's atmosphere. It primarily consists of nitrogen (78%), oxygen (21%), and small amounts of other gases such as argon, carbon dioxide, and trace amounts of neon, helium, and methane.

Air is essential for human life, as it provides the oxygen that our bodies need to produce energy through respiration. We inhale air into our lungs, where oxygen is absorbed into the bloodstream and transported to cells throughout the body. At the same time, carbon dioxide, a waste product of cellular metabolism, is exhaled out of the body through the lungs and back into the atmosphere.

In addition to its role in respiration, air also plays a critical role in regulating the Earth's climate and weather patterns, as well as serving as a medium for sound waves and other forms of energy transfer.

Near-infrared spectroscopy (NIRS) is a non-invasive optical technique that uses the near-infrared region of the electromagnetic spectrum (approximately 700-2500 nanometers) to analyze various chemical and physical properties of materials, primarily in the fields of biomedical research and industry. In medicine, NIRS is often used to measure tissue oxygenation, hemodynamics, and metabolism, providing valuable information about organ function and physiology. This technique is based on the principle that different molecules absorb and scatter near-infrared light differently, allowing for the identification and quantification of specific chromophores, such as oxyhemoglobin, deoxyhemoglobin, and cytochrome c oxidase. NIRS can be employed in a variety of clinical settings, including monitoring cerebral or muscle oxygenation during surgery, assessing tissue viability in wound healing, and studying brain function in neuroscience research.

Myoglobin is a protein found in the muscle tissue, particularly in red or skeletal muscles. It belongs to the globin family and has a similar structure to hemoglobin, another oxygen-binding protein found in red blood cells. Myoglobin's primary function is to store oxygen within the muscle cells, making it readily available for use during periods of increased oxygen demand, such as during physical exertion.

Myoglobin contains heme groups that bind to and release oxygen molecules. The protein has a higher affinity for oxygen than hemoglobin, allowing it to maintain its bound oxygen even in low-oxygen environments. When muscle cells are damaged or undergo necrosis (cell death), myoglobin is released into the bloodstream and can be detected in serum or urine samples. Elevated levels of myoglobin in the blood or urine may indicate muscle injury, trauma, or diseases affecting muscle integrity, such as rhabdomyolysis or muscular dystrophies.

Cardiac output is a measure of the amount of blood that is pumped by the heart in one minute. It is defined as the product of stroke volume (the amount of blood pumped by the left ventricle during each contraction) and heart rate (the number of contractions per minute). Normal cardiac output at rest for an average-sized adult is about 5 to 6 liters per minute. Cardiac output can be increased during exercise or other conditions that require more blood flow, such as during illness or injury. It can be measured noninvasively using techniques such as echocardiography or invasively through a catheter placed in the heart.

Helium is not a medical term, but it's a chemical element with symbol He and atomic number 2. It's a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gases section of the periodic table. In medicine, helium is sometimes used in medical settings for its unique properties, such as being less dense than air, which can help improve the delivery of oxygen to patients with respiratory conditions. For example, heliox, a mixture of helium and oxygen, may be used to reduce the work of breathing in patients with conditions like chronic obstructive pulmonary disease (COPD) or asthma. Additionally, helium is also used in cryogenic medical equipment and in magnetic resonance imaging (MRI) machines to cool the superconducting magnets.

Exercise is defined in the medical context as a physical activity that is planned, structured, and repetitive, with the primary aim of improving or maintaining one or more components of physical fitness. Components of physical fitness include cardiorespiratory endurance, muscular strength, muscular endurance, flexibility, and body composition. Exercise can be classified based on its intensity (light, moderate, or vigorous), duration (length of time), and frequency (number of times per week). Common types of exercise include aerobic exercises, such as walking, jogging, cycling, and swimming; resistance exercises, such as weightlifting; flexibility exercises, such as stretching; and balance exercises. Exercise has numerous health benefits, including reducing the risk of chronic diseases, improving mental health, and enhancing overall quality of life.

A dose-response relationship in the context of drugs refers to the changes in the effects or symptoms that occur as the dose of a drug is increased or decreased. Generally, as the dose of a drug is increased, the severity or intensity of its effects also increases. Conversely, as the dose is decreased, the effects of the drug become less severe or may disappear altogether.

The dose-response relationship is an important concept in pharmacology and toxicology because it helps to establish the safe and effective dosage range for a drug. By understanding how changes in the dose of a drug affect its therapeutic and adverse effects, healthcare providers can optimize treatment plans for their patients while minimizing the risk of harm.

The dose-response relationship is typically depicted as a curve that shows the relationship between the dose of a drug and its effect. The shape of the curve may vary depending on the drug and the specific effect being measured. Some drugs may have a steep dose-response curve, meaning that small changes in the dose can result in large differences in the effect. Other drugs may have a more gradual dose-response curve, where larger changes in the dose are needed to produce significant effects.

In addition to helping establish safe and effective dosages, the dose-response relationship is also used to evaluate the potential therapeutic benefits and risks of new drugs during clinical trials. By systematically testing different doses of a drug in controlled studies, researchers can identify the optimal dosage range for the drug and assess its safety and efficacy.

Spectrophotometry is a technical analytical method used in the field of medicine and science to measure the amount of light absorbed or transmitted by a substance at specific wavelengths. This technique involves the use of a spectrophotometer, an instrument that measures the intensity of light as it passes through a sample.

In medical applications, spectrophotometry is often used in laboratory settings to analyze various biological samples such as blood, urine, and tissues. For example, it can be used to measure the concentration of specific chemicals or compounds in a sample by measuring the amount of light that is absorbed or transmitted at specific wavelengths.

In addition, spectrophotometry can also be used to assess the properties of biological tissues, such as their optical density and thickness. This information can be useful in the diagnosis and treatment of various medical conditions, including skin disorders, eye diseases, and cancer.

Overall, spectrophotometry is a valuable tool for medical professionals and researchers seeking to understand the composition and properties of various biological samples and tissues.

The myocardium is the middle layer of the heart wall, composed of specialized cardiac muscle cells that are responsible for pumping blood throughout the body. It forms the thickest part of the heart wall and is divided into two sections: the left ventricle, which pumps oxygenated blood to the rest of the body, and the right ventricle, which pumps deoxygenated blood to the lungs.

The myocardium contains several types of cells, including cardiac muscle fibers, connective tissue, nerves, and blood vessels. The muscle fibers are arranged in a highly organized pattern that allows them to contract in a coordinated manner, generating the force necessary to pump blood through the heart and circulatory system.

Damage to the myocardium can occur due to various factors such as ischemia (reduced blood flow), infection, inflammation, or genetic disorders. This damage can lead to several cardiac conditions, including heart failure, arrhythmias, and cardiomyopathy.

Altitude is the height above a given level, especially mean sea level. In medical terms, altitude often refers to high altitude, which is generally considered to be 1500 meters (about 5000 feet) or more above sea level. At high altitudes, the air pressure is lower and there is less oxygen available, which can lead to altitude sickness in some people. Symptoms of altitude sickness can include headache, dizziness, shortness of breath, and fatigue. It's important for people who are traveling to high altitudes to allow themselves time to adjust to the lower oxygen levels and to watch for signs of altitude sickness.

Regional blood flow (RBF) refers to the rate at which blood flows through a specific region or organ in the body, typically expressed in milliliters per minute per 100 grams of tissue (ml/min/100g). It is an essential physiological parameter that reflects the delivery of oxygen and nutrients to tissues while removing waste products. RBF can be affected by various factors such as metabolic demands, neural regulation, hormonal influences, and changes in blood pressure or vascular resistance. Measuring RBF is crucial for understanding organ function, diagnosing diseases, and evaluating the effectiveness of treatments.

'Onium compounds' is a general term used in chemistry and biochemistry to describe a class of organic compounds that contain a positively charged functional group. The name 'onium' refers to the positive charge, which is usually located on a nitrogen or phosphorus atom.

The most common onium compounds are ammonium compounds (positive charge on a nitrogen atom) and phosphonium compounds (positive charge on a phosphorus atom). Other examples include sulfonium compounds (positive charge on a sulfur atom) and oxonium compounds (positive charge on an oxygen atom).

In the context of medical research, onium compounds may be studied for their potential use as drugs or diagnostic agents. For example, certain ammonium compounds have been shown to have antimicrobial properties and are used in some disinfectants and sanitizers. Phosphonium compounds have been investigated for their potential use as anti-cancer agents, while sulfonium compounds have been studied for their potential as enzyme inhibitors.

It's worth noting that onium compounds can also be found in nature, including in some biological systems. For example, certain enzymes and signaling molecules contain onium groups that are important for their function.

Hypoxia-Inducible Factor 1 (HIF-1) is a transcription factor that plays a crucial role in the cellular response to low oxygen levels, also known as hypoxia. It is a heterodimeric protein composed of two subunits: HIF-1α and HIF-1β.

Under normoxic conditions (adequate oxygen supply), HIF-1α is constantly produced but rapidly degraded by proteasomes due to the action of prolyl hydroxylases, which mark it for destruction in the presence of oxygen. However, under hypoxic conditions, the activity of prolyl hydroxylases is inhibited, leading to the stabilization and accumulation of HIF-1α.

Once stabilized, HIF-1α translocates to the nucleus and forms a complex with HIF-1β. This complex then binds to hypoxia-responsive elements (HREs) in the promoter regions of various genes involved in angiogenesis, glucose metabolism, erythropoiesis, cell survival, and other processes that help cells adapt to low oxygen levels.

By activating these target genes, HIF-1 plays a critical role in regulating the body's response to hypoxia, including promoting the formation of new blood vessels (angiogenesis), enhancing anaerobic metabolism, and inhibiting cell proliferation and apoptosis under low oxygen conditions. Dysregulation of HIF-1 has been implicated in several diseases, such as cancer, cardiovascular disease, and ischemic disorders.

Lactates, also known as lactic acid, are compounds that are produced by muscles during intense exercise or other conditions of low oxygen supply. They are formed from the breakdown of glucose in the absence of adequate oxygen to complete the full process of cellular respiration. This results in the production of lactate and a hydrogen ion, which can lead to a decrease in pH and muscle fatigue.

In a medical context, lactates may be measured in the blood as an indicator of tissue oxygenation and metabolic status. Elevated levels of lactate in the blood, known as lactic acidosis, can indicate poor tissue perfusion or hypoxia, and may be seen in conditions such as sepsis, cardiac arrest, and severe shock. It is important to note that lactates are not the primary cause of acidemia (low pH) in lactic acidosis, but rather a marker of the underlying process.

Heme is not a medical term per se, but it is a term used in the field of medicine and biology. Heme is a prosthetic group found in hemoproteins, which are proteins that contain a heme iron complex. This complex plays a crucial role in various biological processes, including oxygen transport (in hemoglobin), electron transfer (in cytochromes), and chemical catalysis (in peroxidases and catalases).

The heme group consists of an organic component called a porphyrin ring, which binds to a central iron atom. The iron atom can bind or release electrons, making it essential for redox reactions in the body. Heme is also vital for the formation of hemoglobin and myoglobin, proteins responsible for oxygen transport and storage in the blood and muscles, respectively.

In summary, heme is a complex organic-inorganic structure that plays a critical role in several biological processes, particularly in electron transfer and oxygen transport.

A lung is a pair of spongy, elastic organs in the chest that work together to enable breathing. They are responsible for taking in oxygen and expelling carbon dioxide through the process of respiration. The left lung has two lobes, while the right lung has three lobes. The lungs are protected by the ribcage and are covered by a double-layered membrane called the pleura. The trachea divides into two bronchi, which further divide into smaller bronchioles, leading to millions of tiny air sacs called alveoli, where the exchange of gases occurs.

Metalloporphyrins are a type of porphyrin molecule that contain a metal ion at their center. Porphyrins are complex organic compounds containing four modified pyrrole rings connected to form a planar, aromatic ring known as a porphine. When a metal ion is incorporated into the center of the porphyrin ring, it forms a metalloporphyrin.

These molecules have great biological significance, as they are involved in various essential processes within living organisms. For instance, heme, a type of iron-containing porphyrin, plays a crucial role in oxygen transport and storage in the body by forming part of hemoglobin and myoglobin molecules. Chlorophyll, another metalloporphyrin with magnesium at its center, is essential for photosynthesis in plants, algae, and some bacteria.

Metalloporphyrins have also found applications in several industrial and medical fields, including catalysis, sensors, and pharmaceuticals. Their unique structure and properties make them valuable tools for researchers and scientists to study and utilize in various ways.

Nitrous oxide, also known as laughing gas, is a colorless and non-flammable gas with a slightly sweet odor and taste. In medicine, it's commonly used for its anesthetic and pain reducing effects. It is often used in dental procedures, surgery, and childbirth to help reduce anxiety and provide mild sedation. Nitrous oxide works by binding to the hemoglobin in red blood cells, which reduces the oxygen-carrying capacity of the blood, but this effect is usually not significant at the low concentrations used for analgesia and anxiolysis. It's also considered relatively safe when administered by a trained medical professional because it does not cause depression of the respiratory system or cardiovascular function.

In the context of medicine, iron is an essential micromineral and key component of various proteins and enzymes. It plays a crucial role in oxygen transport, DNA synthesis, and energy production within the body. Iron exists in two main forms: heme and non-heme. Heme iron is derived from hemoglobin and myoglobin in animal products, while non-heme iron comes from plant sources and supplements.

The recommended daily allowance (RDA) for iron varies depending on age, sex, and life stage:

* For men aged 19-50 years, the RDA is 8 mg/day
* For women aged 19-50 years, the RDA is 18 mg/day
* During pregnancy, the RDA increases to 27 mg/day
* During lactation, the RDA for breastfeeding mothers is 9 mg/day

Iron deficiency can lead to anemia, characterized by fatigue, weakness, and shortness of breath. Excessive iron intake may result in iron overload, causing damage to organs such as the liver and heart. Balanced iron levels are essential for maintaining optimal health.

Blood pressure is the force exerted by circulating blood on the walls of the blood vessels. It is measured in millimeters of mercury (mmHg) and is given as two figures:

1. Systolic pressure: This is the pressure when the heart pushes blood out into the arteries.
2. Diastolic pressure: This is the pressure when the heart rests between beats, allowing it to fill with blood.

Normal blood pressure for adults is typically around 120/80 mmHg, although this can vary slightly depending on age, sex, and other factors. High blood pressure (hypertension) is generally considered to be a reading of 130/80 mmHg or higher, while low blood pressure (hypotension) is usually defined as a reading below 90/60 mmHg. It's important to note that blood pressure can fluctuate throughout the day and may be affected by factors such as stress, physical activity, and medication use.

Ascorbic acid is the chemical name for Vitamin C. It is a water-soluble vitamin that is essential for human health. Ascorbic acid is required for the synthesis of collagen, a protein that plays a role in the structure of bones, tendons, ligaments, and blood vessels. It also functions as an antioxidant, helping to protect cells from damage caused by free radicals.

Ascorbic acid cannot be produced by the human body and must be obtained through diet or supplementation. Good food sources of vitamin C include citrus fruits, strawberries, bell peppers, broccoli, and spinach.

In the medical field, ascorbic acid is used to treat or prevent vitamin C deficiency and related conditions, such as scurvy. It may also be used in the treatment of various other health conditions, including common cold, cancer, and cardiovascular disease, although its effectiveness for these uses is still a matter of scientific debate.

Exercise tolerance is a term used to describe the ability of an individual to perform physical activity or exercise without experiencing symptoms such as shortness of breath, chest pain, or undue fatigue. It is often used as a measure of cardiovascular fitness and can be assessed through various tests, such as a stress test or a six-minute walk test. Exercise intolerance may indicate the presence of underlying medical conditions, such as heart disease, lung disease, or deconditioning.

Cell death is the process by which cells cease to function and eventually die. There are several ways that cells can die, but the two most well-known and well-studied forms of cell death are apoptosis and necrosis.

Apoptosis is a programmed form of cell death that occurs as a normal and necessary process in the development and maintenance of healthy tissues. During apoptosis, the cell's DNA is broken down into small fragments, the cell shrinks, and the membrane around the cell becomes fragmented, allowing the cell to be easily removed by phagocytic cells without causing an inflammatory response.

Necrosis, on the other hand, is a form of cell death that occurs as a result of acute tissue injury or overwhelming stress. During necrosis, the cell's membrane becomes damaged and the contents of the cell are released into the surrounding tissue, causing an inflammatory response.

There are also other forms of cell death, such as autophagy, which is a process by which cells break down their own organelles and proteins to recycle nutrients and maintain energy homeostasis, and pyroptosis, which is a form of programmed cell death that occurs in response to infection and involves the activation of inflammatory caspases.

Cell death is an important process in many physiological and pathological processes, including development, tissue homeostasis, and disease. Dysregulation of cell death can contribute to the development of various diseases, including cancer, neurodegenerative disorders, and autoimmune diseases.

Skeletal muscle, also known as striated or voluntary muscle, is a type of muscle that is attached to bones by tendons or aponeuroses and functions to produce movements and support the posture of the body. It is composed of long, multinucleated fibers that are arranged in parallel bundles and are characterized by alternating light and dark bands, giving them a striped appearance under a microscope. Skeletal muscle is under voluntary control, meaning that it is consciously activated through signals from the nervous system. It is responsible for activities such as walking, running, jumping, and lifting objects.

Medical definitions of water generally describe it as a colorless, odorless, tasteless liquid that is essential for all forms of life. It is a universal solvent, making it an excellent medium for transporting nutrients and waste products within the body. Water constitutes about 50-70% of an individual's body weight, depending on factors such as age, sex, and muscle mass.

In medical terms, water has several important functions in the human body:

1. Regulation of body temperature through perspiration and respiration.
2. Acting as a lubricant for joints and tissues.
3. Facilitating digestion by helping to break down food particles.
4. Transporting nutrients, oxygen, and waste products throughout the body.
5. Helping to maintain healthy skin and mucous membranes.
6. Assisting in the regulation of various bodily functions, such as blood pressure and heart rate.

Dehydration can occur when an individual does not consume enough water or loses too much fluid due to illness, exercise, or other factors. This can lead to a variety of symptoms, including dry mouth, fatigue, dizziness, and confusion. Severe dehydration can be life-threatening if left untreated.

The brain is the central organ of the nervous system, responsible for receiving and processing sensory information, regulating vital functions, and controlling behavior, movement, and cognition. It is divided into several distinct regions, each with specific functions:

1. Cerebrum: The largest part of the brain, responsible for higher cognitive functions such as thinking, learning, memory, language, and perception. It is divided into two hemispheres, each controlling the opposite side of the body.
2. Cerebellum: Located at the back of the brain, it is responsible for coordinating muscle movements, maintaining balance, and fine-tuning motor skills.
3. Brainstem: Connects the cerebrum and cerebellum to the spinal cord, controlling vital functions such as breathing, heart rate, and blood pressure. It also serves as a relay center for sensory information and motor commands between the brain and the rest of the body.
4. Diencephalon: A region that includes the thalamus (a major sensory relay station) and hypothalamus (regulates hormones, temperature, hunger, thirst, and sleep).
5. Limbic system: A group of structures involved in emotional processing, memory formation, and motivation, including the hippocampus, amygdala, and cingulate gyrus.

The brain is composed of billions of interconnected neurons that communicate through electrical and chemical signals. It is protected by the skull and surrounded by three layers of membranes called meninges, as well as cerebrospinal fluid that provides cushioning and nutrients.

Physiological adaptation refers to the changes or modifications that occur in an organism's biological functions or structures as a result of environmental pressures or changes. These adaptations enable the organism to survive and reproduce more successfully in its environment. They can be short-term, such as the constriction of blood vessels in response to cold temperatures, or long-term, such as the evolution of longer limbs in animals that live in open environments.

In the context of human physiology, examples of physiological adaptation include:

1. Acclimatization: The process by which the body adjusts to changes in environmental conditions, such as altitude or temperature. For example, when a person moves to a high-altitude location, their body may produce more red blood cells to compensate for the lower oxygen levels, leading to improved oxygen delivery to tissues.

2. Exercise adaptation: Regular physical activity can lead to various physiological adaptations, such as increased muscle strength and endurance, enhanced cardiovascular function, and improved insulin sensitivity.

3. Hormonal adaptation: The body can adjust hormone levels in response to changes in the environment or internal conditions. For instance, during prolonged fasting, the body releases stress hormones like cortisol and adrenaline to help maintain energy levels and prevent muscle wasting.

4. Sensory adaptation: Our senses can adapt to different stimuli over time. For example, when we enter a dark room after being in bright sunlight, it takes some time for our eyes to adjust to the new light level. This process is known as dark adaptation.

5. Aging-related adaptations: As we age, various physiological changes occur that help us adapt to the changing environment and maintain homeostasis. These include changes in body composition, immune function, and cognitive abilities.

In the context of medical terminology, "light" doesn't have a specific or standardized definition on its own. However, it can be used in various medical terms and phrases. For example, it could refer to:

1. Visible light: The range of electromagnetic radiation that can be detected by the human eye, typically between wavelengths of 400-700 nanometers. This is relevant in fields such as ophthalmology and optometry.
2. Therapeutic use of light: In some therapies, light is used to treat certain conditions. An example is phototherapy, which uses various wavelengths of ultraviolet (UV) or visible light for conditions like newborn jaundice, skin disorders, or seasonal affective disorder.
3. Light anesthesia: A state of reduced consciousness in which the patient remains responsive to verbal commands and physical stimulation. This is different from general anesthesia where the patient is completely unconscious.
4. Pain relief using light: Certain devices like transcutaneous electrical nerve stimulation (TENS) units have a 'light' setting, indicating lower intensity or frequency of electrical impulses used for pain management.

Without more context, it's hard to provide a precise medical definition of 'light'.

Adenosine Triphosphate (ATP) is a high-energy molecule that stores and transports energy within cells. It is the main source of energy for most cellular processes, including muscle contraction, nerve impulse transmission, and protein synthesis. ATP is composed of a base (adenine), a sugar (ribose), and three phosphate groups. The bonds between these phosphate groups contain a significant amount of energy, which can be released when the bond between the second and third phosphate group is broken, resulting in the formation of adenosine diphosphate (ADP) and inorganic phosphate. This process is known as hydrolysis and can be catalyzed by various enzymes to drive a wide range of cellular functions. ATP can also be regenerated from ADP through various metabolic pathways, such as oxidative phosphorylation or substrate-level phosphorylation, allowing for the continuous supply of energy to cells.

2,3-Diphosphoglycerate (2,3-DPG) is a molecule found in red blood cells that plays a crucial role in regulating the affinity of hemoglobin for oxygen. It is a byproduct of the glycolytic pathway, which is a series of biochemical reactions that convert glucose into energy.

In the tissues where oxygen demand is high, such as muscles and organs, 2,3-DPG concentrations are typically elevated. This molecule binds to deoxygenated hemoglobin at specific sites on the beta chains, reducing its affinity for oxygen and promoting the release of oxygen to the tissues.

Conversely, in the lungs where oxygen is abundant, 2,3-DPG concentrations are lower, allowing hemoglobin to bind more readily to oxygen and load up with oxygen for delivery to the tissues. Therefore, 2,3-DPG helps optimize the matching of oxygen supply and demand in the body.

Obstructive lung disease is a category of respiratory diseases characterized by airflow limitation that causes difficulty in completely emptying the alveoli (tiny air sacs) of the lungs during exhaling. This results in the trapping of stale air and prevents fresh air from entering the alveoli, leading to various symptoms such as coughing, wheezing, shortness of breath, and decreased exercise tolerance.

The most common obstructive lung diseases include:

1. Chronic Obstructive Pulmonary Disease (COPD): A progressive disease that includes chronic bronchitis and emphysema, often caused by smoking or exposure to harmful pollutants.
2. Asthma: A chronic inflammatory disorder of the airways characterized by variable airflow obstruction, bronchial hyperresponsiveness, and an underlying inflammation. Symptoms can be triggered by various factors such as allergens, irritants, or physical activity.
3. Bronchiectasis: A condition in which the airways become abnormally widened, scarred, and thickened due to chronic inflammation or infection, leading to mucus buildup and impaired clearance.
4. Cystic Fibrosis: An inherited genetic disorder that affects the exocrine glands, resulting in thick and sticky mucus production in various organs, including the lungs. This can lead to chronic lung infections, inflammation, and airway obstruction.
5. Alpha-1 Antitrypsin Deficiency: A genetic condition characterized by low levels of alpha-1 antitrypsin protein, which leads to uncontrolled protease enzyme activity that damages the lung tissue, causing emphysema-like symptoms.

Treatment for obstructive lung diseases typically involves bronchodilators (to relax and widen the airways), corticosteroids (to reduce inflammation), and lifestyle modifications such as smoking cessation and pulmonary rehabilitation programs. In severe cases, oxygen therapy or even lung transplantation may be considered.

Abnormal hemoglobins refer to variants of the oxygen-carrying protein found in red blood cells, which differ from the normal adult hemoglobin (HbA) in terms of their structure and function. These variations can result from genetic mutations that affect the composition of the globin chains in the hemoglobin molecule. Some abnormal hemoglobins are clinically insignificant, while others can lead to various medical conditions such as hemolytic anemia, thalassemia, or sickle cell disease. Examples of abnormal hemoglobins include HbS (associated with sickle cell anemia), HbC, HbE, and HbF (fetal hemoglobin). These variants can be detected through specialized laboratory tests, such as hemoglobin electrophoresis or high-performance liquid chromatography (HPLC).

Hydroxides are inorganic compounds that contain the hydroxide ion (OH−). They are formed when a base, which is an electron pair donor, reacts with water. The hydroxide ion consists of one oxygen atom and one hydrogen atom, and it carries a negative charge. Hydroxides are basic in nature due to their ability to donate hydroxide ions in solution, which increases the pH and makes the solution more alkaline. Common examples of hydroxides include sodium hydroxide (NaOH), potassium hydroxide (KOH), and calcium hydroxide (Ca(OH)2). They have various applications in industry, medicine, and research.

Enzyme inhibitors are substances that bind to an enzyme and decrease its activity, preventing it from catalyzing a chemical reaction in the body. They can work by several mechanisms, including blocking the active site where the substrate binds, or binding to another site on the enzyme to change its shape and prevent substrate binding. Enzyme inhibitors are often used as drugs to treat various medical conditions, such as high blood pressure, abnormal heart rhythms, and bacterial infections. They can also be found naturally in some foods and plants, and can be used in research to understand enzyme function and regulation.

Peroxides, in a medical context, most commonly refer to chemical compounds that contain the peroxide ion (O2−2). Peroxides are characterized by the presence of an oxygen-oxygen single bond and can be found in various substances.

In dentistry, hydrogen peroxide (H2O2) is a widely used agent for teeth whitening or bleaching due to its oxidizing properties. It can help remove stains and discoloration on the tooth surface by breaking down into water and oxygen-free radicals, which react with the stain molecules, ultimately leading to their oxidation and elimination.

However, it is essential to note that high concentrations of hydrogen peroxide or prolonged exposure can cause tooth sensitivity, irritation to the oral soft tissues, and potential damage to the dental pulp. Therefore, professional supervision and appropriate concentration control are crucial when using peroxides for dental treatments.

Atmospheric pressure, also known as barometric pressure, is the force per unit area exerted by the Earth's atmosphere on objects. It is measured in units of force per unit area, such as pascals (Pa), pounds per square inch (psi), or, more commonly, millimeters of mercury (mmHg).

Standard atmospheric pressure at sea level is defined as 101,325 Pa (14.7 psi) or 760 mmHg (29.92 inches of mercury). Atmospheric pressure decreases with increasing altitude, as the weight of the air above becomes less. This decrease in pressure can affect various bodily functions, such as respiration and digestion, and may require adaptation for individuals living at high altitudes. Changes in atmospheric pressure can also be used to predict weather patterns, as low pressure systems are often associated with stormy or inclement weather.

"Wistar rats" are a strain of albino rats that are widely used in laboratory research. They were developed at the Wistar Institute in Philadelphia, USA, and were first introduced in 1906. Wistar rats are outbred, which means that they are genetically diverse and do not have a fixed set of genetic characteristics like inbred strains.

Wistar rats are commonly used as animal models in biomedical research because of their size, ease of handling, and relatively low cost. They are used in a wide range of research areas, including toxicology, pharmacology, nutrition, cancer, cardiovascular disease, and behavioral studies. Wistar rats are also used in safety testing of drugs, medical devices, and other products.

Wistar rats are typically larger than many other rat strains, with males weighing between 500-700 grams and females weighing between 250-350 grams. They have a lifespan of approximately 2-3 years. Wistar rats are also known for their docile and friendly nature, making them easy to handle and work with in the laboratory setting.

NADH, NADPH oxidoreductases are a class of enzymes that catalyze the redox reaction between NADH or NADPH and various electron acceptors. These enzymes play a crucial role in cellular metabolism by transferring electrons from NADH or NADPH to other molecules, which is essential for many biochemical reactions.

NADH (nicotinamide adenine dinucleotide hydrogen) and NADPH (nicotinamide adenine dinucleotide phosphate hydrogen) are coenzymes that act as electron carriers in redox reactions. They consist of a nicotinamide ring, which undergoes reduction or oxidation by accepting or donating electrons and a proton (H+).

NADH, NADPH oxidoreductases are classified based on their structure and mechanism of action. Some examples include:

1. Dehydrogenases: These enzymes catalyze the oxidation of NADH or NADPH to NAD+ or NADP+ while reducing an organic substrate. Examples include lactate dehydrogenase, alcohol dehydrogenase, and malate dehydrogenase.
2. Oxidases: These enzymes catalyze the oxidation of NADH or NADPH to NAD+ or NADP+ while reducing molecular oxygen (O2) to water (H2O). Examples include NADH oxidase and NADPH oxidase.
3. Reductases: These enzymes catalyze the reduction of various electron acceptors using NADH or NADPH as a source of electrons. Examples include glutathione reductase, thioredoxin reductase, and nitrate reductase.

Overall, NADH, NADPH oxidoreductases are essential for maintaining the redox balance in cells and play a critical role in various metabolic pathways, including energy production, detoxification, and biosynthesis.

Peroxidases are a group of enzymes that catalyze the oxidation of various substrates using hydrogen peroxide (H2O2) as the electron acceptor. These enzymes contain a heme prosthetic group, which plays a crucial role in their catalytic activity. Peroxidases are widely distributed in nature and can be found in plants, animals, and microorganisms. They play important roles in various biological processes, including defense against oxidative stress, lignin degradation, and host-pathogen interactions. Some common examples of peroxidases include glutathione peroxidase, which helps protect cells from oxidative damage, and horseradish peroxidase, which is often used in laboratory research.

I believe there might be a misunderstanding in your question. "Dogs" is not a medical term or condition. It is the common name for a domesticated carnivore of the family Canidae, specifically the genus Canis, which includes wolves, foxes, and other extant and extinct species of mammals. Dogs are often kept as pets and companions, and they have been bred in a wide variety of forms and sizes for different purposes, such as hunting, herding, guarding, assisting police and military forces, and providing companionship and emotional support.

If you meant to ask about a specific medical condition or term related to dogs, please provide more context so I can give you an accurate answer.

Animal disease models are specialized animals, typically rodents such as mice or rats, that have been genetically engineered or exposed to certain conditions to develop symptoms and physiological changes similar to those seen in human diseases. These models are used in medical research to study the pathophysiology of diseases, identify potential therapeutic targets, test drug efficacy and safety, and understand disease mechanisms.

The genetic modifications can include knockout or knock-in mutations, transgenic expression of specific genes, or RNA interference techniques. The animals may also be exposed to environmental factors such as chemicals, radiation, or infectious agents to induce the disease state.

Examples of animal disease models include:

1. Mouse models of cancer: Genetically engineered mice that develop various types of tumors, allowing researchers to study cancer initiation, progression, and metastasis.
2. Alzheimer's disease models: Transgenic mice expressing mutant human genes associated with Alzheimer's disease, which exhibit amyloid plaque formation and cognitive decline.
3. Diabetes models: Obese and diabetic mouse strains like the NOD (non-obese diabetic) or db/db mice, used to study the development of type 1 and type 2 diabetes, respectively.
4. Cardiovascular disease models: Atherosclerosis-prone mice, such as ApoE-deficient or LDLR-deficient mice, that develop plaque buildup in their arteries when fed a high-fat diet.
5. Inflammatory bowel disease models: Mice with genetic mutations affecting intestinal barrier function and immune response, such as IL-10 knockout or SAMP1/YitFc mice, which develop colitis.

Animal disease models are essential tools in preclinical research, but it is important to recognize their limitations. Differences between species can affect the translatability of results from animal studies to human patients. Therefore, researchers must carefully consider the choice of model and interpret findings cautiously when applying them to human diseases.

The term "diving" is generally not used in the context of medical definitions. However, when referring to diving in relation to a medical or physiological context, it usually refers to the act of submerging the body underwater, typically for activities such as swimming, snorkeling, or scuba diving.

In a medical or physiological sense, diving can have specific effects on the human body due to changes in pressure, temperature, and exposure to water. Some of these effects include:

* Changes in lung volume and gas exchange due to increased ambient pressure at depth.
* Decompression sickness (DCS) or nitrogen narcosis, which can occur when dissolved gases form bubbles in the body during ascent from a dive.
* Hypothermia, which can occur if the water is cold and the diver is not adequately insulated.
* Barotrauma, which can occur due to pressure differences between the middle ear or sinuses and the surrounding environment.
* Other medical conditions such as seizures or heart problems can also be exacerbated by diving.

It's important for divers to undergo proper training and certification, follow safe diving practices, and monitor their health before and after dives to minimize the risks associated with diving.

Temperature, in a medical context, is a measure of the degree of hotness or coldness of a body or environment. It is usually measured using a thermometer and reported in degrees Celsius (°C), degrees Fahrenheit (°F), or kelvin (K). In the human body, normal core temperature ranges from about 36.5-37.5°C (97.7-99.5°F) when measured rectally, and can vary slightly depending on factors such as time of day, physical activity, and menstrual cycle. Elevated body temperature is a common sign of infection or inflammation, while abnormally low body temperature can indicate hypothermia or other medical conditions.

Nitrates are chemical compounds that consist of a nitrogen atom bonded to three oxygen atoms (NO3-). In the context of medical science, nitrates are often discussed in relation to their use as medications or their presence in food and water.

As medications, nitrates are commonly used to treat angina (chest pain) caused by coronary artery disease. Nitrates work by relaxing and widening blood vessels, which improves blood flow and reduces the workload on the heart. Some examples of nitrate medications include nitroglycerin, isosorbide dinitrate, and isosorbide mononitrate.

In food and water, nitrates are naturally occurring compounds that can be found in a variety of vegetables, such as spinach, beets, and lettuce. They can also be present in fertilizers and industrial waste, which can contaminate groundwater and surface water sources. While nitrates themselves are not harmful, they can be converted into potentially harmful compounds called nitrites under certain conditions, particularly in the digestive system of young children or in the presence of bacteria such as those found in unpasteurized foods. Excessive levels of nitrites can react with hemoglobin in the blood to form methemoglobin, which cannot transport oxygen effectively and can lead to a condition called methemoglobinemia.

Xanthine is a purine base, which is a naturally occurring heterocyclic aromatic organic compound. It is formed in the body during the metabolism of purines, and it's a normal intermediate in the breakdown of nucleotides to uric acid. Xanthine is also found in various foods and beverages, such as coffee, tea, and chocolate. In the medical field, xanthine may refer to a class of drugs called xanthine derivatives, which include theophylline and caffeine, that act as bronchodilators and cardiac stimulants.

Molecular sequence data refers to the specific arrangement of molecules, most commonly nucleotides in DNA or RNA, or amino acids in proteins, that make up a biological macromolecule. This data is generated through laboratory techniques such as sequencing, and provides information about the exact order of the constituent molecules. This data is crucial in various fields of biology, including genetics, evolution, and molecular biology, allowing for comparisons between different organisms, identification of genetic variations, and studies of gene function and regulation.

I'm happy to help! However, it seems like there are two terms combined into one request: "Mitochondria" and "Heart." I will provide separate definitions for each.

Mitochondrion (singular) or Mitochondria (plural): These are specialized structures found in the cytoplasm of most eukaryotic cells (cells with a true nucleus), including human cells. They are often referred to as the "powerhouse" of the cell because they generate energy in the form of ATP (adenosine triphosphate) through a process called oxidative phosphorylation. Mitochondria contain their own DNA, which is distinct from the nuclear DNA, and are believed to have originated from ancient bacteria that established a symbiotic relationship with primitive eukaryotic cells.

Heart: In human anatomy, the heart is a muscular organ responsible for pumping blood throughout the body. It is located in the thoracic cavity, slightly left of the center, and is enclosed by the pericardium, a double-walled sac that provides protection and lubrication for the heart's movement. The human heart is divided into four chambers: two atria on the top and two ventricles on the bottom. The right side of the heart receives deoxygenated blood from the body and pumps it to the lungs, while the left side receives oxygenated blood from the lungs and pumps it to the rest of the body. The heart's pumping action is regulated by electrical signals that originate in a group of specialized cardiac muscle cells called the sinoatrial node (SA node).

"Spin labels" are a term used in the field of magnetic resonance, including nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR). They refer to molecules or atoms that have been chemically attached to a system of interest and possess a stable, unpaired electron. This unpaired electron behaves like a tiny magnet and can be manipulated using magnetic fields and radiofrequency pulses in EPR experiments. The resulting changes in the electron's spin state can provide information about the local environment, dynamics, and structure of the system to which it is attached. Spin labels are often used in biochemistry and materials science to study complex biological systems or materials at the molecular level.

Neutrophils are a type of white blood cell that are part of the immune system's response to infection. They are produced in the bone marrow and released into the bloodstream where they circulate and are able to move quickly to sites of infection or inflammation in the body. Neutrophils are capable of engulfing and destroying bacteria, viruses, and other foreign substances through a process called phagocytosis. They are also involved in the release of inflammatory mediators, which can contribute to tissue damage in some cases. Neutrophils are characterized by the presence of granules in their cytoplasm, which contain enzymes and other proteins that help them carry out their immune functions.

Photosensitizing agents are substances that, when exposed to light, particularly ultraviolet or visible light, can cause chemical reactions leading to the production of reactive oxygen species. These reactive oxygen species can interact with biological tissues, leading to damage and a variety of phototoxic or photoallergic adverse effects.

Photosensitizing agents are used in various medical fields, including dermatology and oncology. In dermatology, they are often used in the treatment of conditions such as psoriasis and eczema, where a photosensitizer is applied to the skin and then activated with light to reduce inflammation and slow the growth of skin cells.

In oncology, photosensitizing agents are used in photodynamic therapy (PDT), a type of cancer treatment that involves administering a photosensitizer, allowing it to accumulate in cancer cells, and then exposing the area to light. The light activates the photosensitizer, which produces reactive oxygen species that damage the cancer cells, leading to their death.

Examples of photosensitizing agents include porphyrins, chlorophyll derivatives, and certain antibiotics such as tetracyclines and fluoroquinolones. It is important for healthcare providers to be aware of the potential for photosensitivity when prescribing these medications and to inform patients of the risks associated with exposure to light.

Photosynthesis is not strictly a medical term, but it is a fundamental biological process with significant implications for medicine, particularly in understanding energy production in cells and the role of oxygen in sustaining life. Here's a general biological definition:

Photosynthesis is a process by which plants, algae, and some bacteria convert light energy, usually from the sun, into chemical energy in the form of organic compounds, such as glucose (or sugar), using water and carbon dioxide. This process primarily takes place in the chloroplasts of plant cells, specifically in structures called thylakoids. The overall reaction can be summarized as:

6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2

In this equation, carbon dioxide (CO2) and water (H2O) are the reactants, while glucose (C6H12O6) and oxygen (O2) are the products. Photosynthesis has two main stages: the light-dependent reactions and the light-independent reactions (Calvin cycle). The light-dependent reactions occur in the thylakoid membrane and involve the conversion of light energy into ATP and NADPH, which are used to power the Calvin cycle. The Calvin cycle takes place in the stroma of chloroplasts and involves the synthesis of glucose from CO2 and water using the ATP and NADPH generated during the light-dependent reactions.

Understanding photosynthesis is crucial for understanding various biological processes, including cellular respiration, plant metabolism, and the global carbon cycle. Additionally, research into artificial photosynthesis has potential applications in renewable energy production and environmental remediation.

Hemodilution is a medical term that refers to the reduction in the concentration of certain components in the blood, usually referring to red blood cells (RBCs) or hemoglobin. This occurs when an individual's plasma volume expands due to the infusion of intravenous fluids or the body's own production of fluid, such as during severe infection or inflammation. As a result, the number of RBCs per unit of blood decreases, leading to a lower hematocrit and hemoglobin level. It is important to note that while hemodilution reduces the concentration of RBCs in the blood, it does not necessarily indicate anemia or blood loss.

Glutathione peroxidase (GPx) is a family of enzymes with peroxidase activity whose main function is to protect the organism from oxidative damage. They catalyze the reduction of hydrogen peroxide, lipid peroxides, and organic hydroperoxides to water or corresponding alcohols, using glutathione (GSH) as a reducing agent, which is converted to its oxidized form (GSSG). There are several isoforms of GPx found in different tissues, including GPx1 (also known as cellular GPx), GPx2 (gastrointestinal GPx), GPx3 (plasma GPx), GPx4 (also known as phospholipid hydroperoxide GPx), and GPx5-GPx8. These enzymes play crucial roles in various biological processes, such as antioxidant defense, cell signaling, and apoptosis regulation.

Biological Oxygen Demand (BOD) analysis is a laboratory test used to determine the amount of oxygen consumed by microorganisms during the decomposition of organic matter in a sample of water. It is a measure of the pollution potential of a wastewater, with higher BOD values indicating greater pollution. The test involves measuring the difference in dissolved oxygen (DO) levels between a controlled incubation period (usually five days) and the initial DO level. The difference is reported as the BOD, typically expressed in milligrams per liter (mg/L) or parts per million (ppm). This information helps in assessing the effectiveness of wastewater treatment processes and monitoring water quality in rivers, streams, and other bodies of water.

NAD (Nicotinamide Adenine Dinucleotide) is a coenzyme found in all living cells. It plays an essential role in cellular metabolism, particularly in redox reactions, where it acts as an electron carrier. NAD exists in two forms: NAD+, which accepts electrons and becomes reduced to NADH. This pairing of NAD+/NADH is involved in many fundamental biological processes such as generating energy in the form of ATP during cellular respiration, and serving as a critical cofactor for various enzymes that regulate cellular functions like DNA repair, gene expression, and cell death.

Maintaining optimal levels of NAD+/NADH is crucial for overall health and longevity, as it declines with age and in certain disease states. Therefore, strategies to boost NAD+ levels are being actively researched for their potential therapeutic benefits in various conditions such as aging, neurodegenerative disorders, and metabolic diseases.

Glycolysis is a fundamental metabolic pathway that occurs in the cytoplasm of cells, consisting of a series of biochemical reactions. It's the process by which a six-carbon glucose molecule is broken down into two three-carbon pyruvate molecules. This process generates a net gain of two ATP molecules (the main energy currency in cells), two NADH molecules, and two water molecules.

Glycolysis can be divided into two stages: the preparatory phase (or 'energy investment' phase) and the payoff phase (or 'energy generation' phase). During the preparatory phase, glucose is phosphorylated twice to form glucose-6-phosphate and then converted to fructose-1,6-bisphosphate. These reactions consume two ATP molecules but set up the subsequent breakdown of fructose-1,6-bisphosphate into triose phosphates in the payoff phase. In this second stage, each triose phosphate is further oxidized and degraded to produce one pyruvate molecule, one NADH molecule, and one ATP molecule through substrate-level phosphorylation.

Glycolysis does not require oxygen to proceed; thus, it can occur under both aerobic (with oxygen) and anaerobic (without oxygen) conditions. In the absence of oxygen, the pyruvate produced during glycolysis is further metabolized through fermentation pathways such as lactic acid fermentation or alcohol fermentation to regenerate NAD+, which is necessary for glycolysis to continue.

In summary, glycolysis is a crucial process in cellular energy metabolism, allowing cells to convert glucose into ATP and other essential molecules while also serving as a starting point for various other biochemical pathways.

A cell line is a culture of cells that are grown in a laboratory for use in research. These cells are usually taken from a single cell or group of cells, and they are able to divide and grow continuously in the lab. Cell lines can come from many different sources, including animals, plants, and humans. They are often used in scientific research to study cellular processes, disease mechanisms, and to test new drugs or treatments. Some common types of human cell lines include HeLa cells (which come from a cancer patient named Henrietta Lacks), HEK293 cells (which come from embryonic kidney cells), and HUVEC cells (which come from umbilical vein endothelial cells). It is important to note that cell lines are not the same as primary cells, which are cells that are taken directly from a living organism and have not been grown in the lab.

C57BL/6 (C57 Black 6) is an inbred strain of laboratory mouse that is widely used in biomedical research. The term "inbred" refers to a strain of animals where matings have been carried out between siblings or other closely related individuals for many generations, resulting in a population that is highly homozygous at most genetic loci.

The C57BL/6 strain was established in 1920 by crossing a female mouse from the dilute brown (DBA) strain with a male mouse from the black strain. The resulting offspring were then interbred for many generations to create the inbred C57BL/6 strain.

C57BL/6 mice are known for their robust health, longevity, and ease of handling, making them a popular choice for researchers. They have been used in a wide range of biomedical research areas, including studies of cancer, immunology, neuroscience, cardiovascular disease, and metabolism.

One of the most notable features of the C57BL/6 strain is its sensitivity to certain genetic modifications, such as the introduction of mutations that lead to obesity or impaired glucose tolerance. This has made it a valuable tool for studying the genetic basis of complex diseases and traits.

Overall, the C57BL/6 inbred mouse strain is an important model organism in biomedical research, providing a valuable resource for understanding the genetic and molecular mechanisms underlying human health and disease.

Enzyme activation refers to the process by which an enzyme becomes biologically active and capable of carrying out its specific chemical or biological reaction. This is often achieved through various post-translational modifications, such as proteolytic cleavage, phosphorylation, or addition of cofactors or prosthetic groups to the enzyme molecule. These modifications can change the conformation or structure of the enzyme, exposing or creating a binding site for the substrate and allowing the enzymatic reaction to occur.

For example, in the case of proteolytic cleavage, an inactive precursor enzyme, known as a zymogen, is cleaved into its active form by a specific protease. This is seen in enzymes such as trypsin and chymotrypsin, which are initially produced in the pancreas as inactive precursors called trypsinogen and chymotrypsinogen, respectively. Once they reach the small intestine, they are activated by enteropeptidase, a protease that cleaves a specific peptide bond, releasing the active enzyme.

Phosphorylation is another common mechanism of enzyme activation, where a phosphate group is added to a specific serine, threonine, or tyrosine residue on the enzyme by a protein kinase. This modification can alter the conformation of the enzyme and create a binding site for the substrate, allowing the enzymatic reaction to occur.

Enzyme activation is a crucial process in many biological pathways, as it allows for precise control over when and where specific reactions take place. It also provides a mechanism for regulating enzyme activity in response to various signals and stimuli, such as hormones, neurotransmitters, or changes in the intracellular environment.

Hematocrit is a medical term that refers to the percentage of total blood volume that is made up of red blood cells. It is typically measured as part of a complete blood count (CBC) test. A high hematocrit may indicate conditions such as dehydration, polycythemia, or living at high altitudes, while a low hematocrit may be a sign of anemia, bleeding, or overhydration. It is important to note that hematocrit values can vary depending on factors such as age, gender, and pregnancy status.

Artificial respiration is an emergency procedure that can be used to provide oxygen to a person who is not breathing or is breathing inadequately. It involves manually forcing air into the lungs, either by compressing the chest or using a device to deliver breaths. The goal of artificial respiration is to maintain adequate oxygenation of the body's tissues and organs until the person can breathe on their own or until advanced medical care arrives. Artificial respiration may be used in conjunction with cardiopulmonary resuscitation (CPR) in cases of cardiac arrest.

Nitrogen is not typically referred to as a medical term, but it is an element that is crucial to medicine and human life.

In a medical context, nitrogen is often mentioned in relation to gas analysis, respiratory therapy, or medical gases. Nitrogen (N) is a colorless, odorless, and nonreactive gas that makes up about 78% of the Earth's atmosphere. It is an essential element for various biological processes, such as the growth and maintenance of organisms, because it is a key component of amino acids, nucleic acids, and other organic compounds.

In some medical applications, nitrogen is used to displace oxygen in a mixture to create a controlled environment with reduced oxygen levels (hypoxic conditions) for therapeutic purposes, such as in certain types of hyperbaric chambers. Additionally, nitrogen gas is sometimes used in cryotherapy, where extremely low temperatures are applied to tissues to reduce pain, swelling, and inflammation.

However, it's important to note that breathing pure nitrogen can be dangerous, as it can lead to unconsciousness and even death due to lack of oxygen (asphyxiation) within minutes.

Physical endurance is the ability of an individual to withstand and resist physical fatigue over prolonged periods of strenuous activity, exercise, or exertion. It involves the efficient functioning of various body systems, including the cardiovascular system (heart, blood vessels, and blood), respiratory system (lungs and airways), and musculoskeletal system (muscles, bones, tendons, ligaments, and cartilage).

Physical endurance is often measured in terms of aerobic capacity or stamina, which refers to the body's ability to supply oxygen to muscles during sustained physical activity. It can be improved through regular exercise, such as running, swimming, cycling, or weightlifting, that challenges the body's major muscle groups and raises the heart rate for extended periods.

Factors that influence physical endurance include genetics, age, sex, fitness level, nutrition, hydration, sleep quality, stress management, and overall health status. It is essential to maintain good physical endurance to perform daily activities efficiently, reduce the risk of chronic diseases, and enhance overall well-being.

A cell line that is derived from tumor cells and has been adapted to grow in culture. These cell lines are often used in research to study the characteristics of cancer cells, including their growth patterns, genetic changes, and responses to various treatments. They can be established from many different types of tumors, such as carcinomas, sarcomas, and leukemias. Once established, these cell lines can be grown and maintained indefinitely in the laboratory, allowing researchers to conduct experiments and studies that would not be feasible using primary tumor cells. It is important to note that tumor cell lines may not always accurately represent the behavior of the original tumor, as they can undergo genetic changes during their time in culture.

Respiratory insufficiency is a condition characterized by the inability of the respiratory system to maintain adequate gas exchange, resulting in an inadequate supply of oxygen and/or removal of carbon dioxide from the body. This can occur due to various causes, such as lung diseases (e.g., chronic obstructive pulmonary disease, pneumonia), neuromuscular disorders (e.g., muscular dystrophy, spinal cord injury), or other medical conditions that affect breathing mechanics and/or gas exchange.

Respiratory insufficiency can manifest as hypoxemia (low oxygen levels in the blood) and/or hypercapnia (high carbon dioxide levels in the blood). Symptoms of respiratory insufficiency may include shortness of breath, rapid breathing, fatigue, confusion, and in severe cases, loss of consciousness or even death. Treatment depends on the underlying cause and severity of the condition and may include oxygen therapy, mechanical ventilation, medications, and/or other supportive measures.

Retinopathy of Prematurity (ROP) is a potentially sight-threatening proliferative retinal vascular disorder that primarily affects prematurely born infants, particularly those with low birth weight and/or young gestational age. It is characterized by the abnormal growth and development of retinal blood vessels due to disturbances in the oxygen supply and metabolic demands during critical phases of fetal development.

The condition can be classified into various stages (1-5) based on its severity, with stages 4 and 5 being more severe forms that may lead to retinal detachment and blindness if left untreated. The pathogenesis of ROP involves an initial phase of vessel loss and regression in the central retina, followed by a secondary phase of abnormal neovascularization, which can cause fibrosis, traction, and ultimately, retinal detachment.

ROP is typically managed with a multidisciplinary approach involving ophthalmologists, neonatologists, and pediatricians. Treatment options include laser photocoagulation, cryotherapy, intravitreal anti-VEGF injections, or even surgical interventions to prevent retinal detachment and preserve vision. Regular screening examinations are crucial for early detection and timely management of ROP in at-risk infants.

Procollagen-proline dioxygenase is an enzyme that belongs to the family of oxidoreductases, specifically those acting on the CH-NH group of donors with oxygen as an acceptor. This enzyme is involved in the post-translational modification of procollagens, which are the precursors of collagen, a crucial protein found in connective tissues such as tendons, ligaments, and skin.

Procollagen-proline dioxygenase catalyzes the reaction that adds two hydroxyl groups to specific proline residues in the procollagen molecule, converting them into hydroxyprolines. This modification is essential for the proper folding and stabilization of the collagen triple helix structure, which provides strength and resilience to connective tissues.

The enzyme requires iron as a cofactor and molecular oxygen as a substrate, with vitamin C (ascorbic acid) acting as an essential cofactor in the reaction cycle. The proper functioning of procollagen-proline dioxygenase is critical for maintaining the integrity and health of connective tissues, and deficiencies or mutations in this enzyme can lead to various connective tissue disorders, such as scurvy (caused by vitamin C deficiency) or certain forms of osteogenesis imperfecta (a genetic disorder characterized by fragile bones).

In medical terms, gases refer to the state of matter that has no fixed shape or volume and expands to fill any container it is placed in. Gases in the body can be normal, such as the oxygen, carbon dioxide, and nitrogen that are present in the lungs and blood, or abnormal, such as gas that accumulates in the digestive tract due to conditions like bloating or swallowing air.

Gases can also be used medically for therapeutic purposes, such as in the administration of anesthesia or in the treatment of certain respiratory conditions with oxygen therapy. Additionally, measuring the amount of gas in the body, such as through imaging studies like X-rays or CT scans, can help diagnose various medical conditions.

Glucose oxidase (GOD) is an enzyme that catalyzes the oxidation of D-glucose to D-glucono-1,5-lactone, while reducing oxygen to hydrogen peroxide in the process. This reaction is a part of the metabolic pathway in some organisms that convert glucose into energy. The systematic name for this enzyme is D-glucose:oxygen 1-oxidoreductase.

Glucose oxidase is commonly found in certain fungi, such as Aspergillus niger, and it has various applications in industry, medicine, and research. For instance, it's used in the production of glucose sensors for monitoring blood sugar levels, in the detection and quantification of glucose in food and beverages, and in the development of biosensors for environmental monitoring.

It's worth noting that while glucose oxidase has many applications, it should not be confused with glutathione peroxidase, another enzyme involved in the reduction of hydrogen peroxide to water.

Respiratory burst is a term used in the field of biology, particularly in the context of immunology and cellular processes. It does not have a direct application to clinical medicine, but it is important for understanding certain physiological and pathophysiological mechanisms. Here's a definition of respiratory burst:

Respiratory burst is a rapid increase in oxygen consumption by phagocytic cells (like neutrophils, monocytes, and macrophages) following their activation in response to various stimuli, such as pathogens or inflammatory molecules. This process is part of the innate immune response and serves to eliminate invading microorganisms.

The respiratory burst involves the activation of NADPH oxidase, an enzyme complex present in the membrane of phagosomes (the compartment where pathogens are engulfed). Upon activation, NADPH oxidase catalyzes the reduction of oxygen to superoxide radicals, which then dismutate to form hydrogen peroxide. These reactive oxygen species (ROS) can directly kill or damage microorganisms and also serve as signaling molecules for other immune cells.

While respiratory burst is a crucial part of the immune response, excessive or dysregulated ROS production can contribute to tissue damage and chronic inflammation, which have implications in various pathological conditions, such as atherosclerosis, neurodegenerative diseases, and cancer.

Microcirculation is the circulation of blood in the smallest blood vessels, including arterioles, venules, and capillaries. It's responsible for the delivery of oxygen and nutrients to the tissues and the removal of waste products. The microcirculation plays a crucial role in maintaining tissue homeostasis and is regulated by various physiological mechanisms such as autonomic nervous system activity, local metabolic factors, and hormones.

Impairment of microcirculation can lead to tissue hypoxia, inflammation, and organ dysfunction, which are common features in several diseases, including diabetes, hypertension, sepsis, and ischemia-reperfusion injury. Therefore, understanding the structure and function of the microcirculation is essential for developing new therapeutic strategies to treat these conditions.

Brain hypoxia is a medical condition characterized by a reduced supply of oxygen to the brain. The brain requires a continuous supply of oxygen to function properly, and even a brief period of hypoxia can cause significant damage to brain cells.

Hypoxia can result from various conditions, such as cardiac arrest, respiratory failure, carbon monoxide poisoning, or high altitude exposure. When the brain is deprived of oxygen, it can lead to a range of symptoms, including confusion, disorientation, seizures, loss of consciousness, and ultimately, brain death.

Brain hypoxia is a medical emergency that requires immediate treatment to prevent long-term neurological damage or death. Treatment typically involves addressing the underlying cause of hypoxia, such as administering oxygen therapy, resuscitating the heart, or treating respiratory failure. In some cases, more invasive treatments, such as therapeutic hypothermia or mechanical ventilation, may be necessary to prevent further brain damage.

Messenger RNA (mRNA) is a type of RNA (ribonucleic acid) that carries genetic information copied from DNA in the form of a series of three-base code "words," each of which specifies a particular amino acid. This information is used by the cell's machinery to construct proteins, a process known as translation. After being transcribed from DNA, mRNA travels out of the nucleus to the ribosomes in the cytoplasm where protein synthesis occurs. Once the protein has been synthesized, the mRNA may be degraded and recycled. Post-transcriptional modifications can also occur to mRNA, such as alternative splicing and addition of a 5' cap and a poly(A) tail, which can affect its stability, localization, and translation efficiency.

Pulmonary circulation refers to the process of blood flow through the lungs, where blood picks up oxygen and releases carbon dioxide. This is a vital part of the overall circulatory system, which delivers nutrients and oxygen to the body's cells while removing waste products like carbon dioxide.

In pulmonary circulation, deoxygenated blood from the systemic circulation returns to the right atrium of the heart via the superior and inferior vena cava. The blood then moves into the right ventricle through the tricuspid valve and gets pumped into the pulmonary artery when the right ventricle contracts.

The pulmonary artery divides into smaller vessels called arterioles, which further branch into a vast network of tiny capillaries in the lungs. Here, oxygen from the alveoli diffuses into the blood, binding to hemoglobin in red blood cells, while carbon dioxide leaves the blood and is exhaled through the nose or mouth.

The now oxygenated blood collects in venules, which merge to form pulmonary veins. These veins transport the oxygen-rich blood back to the left atrium of the heart, where it enters the systemic circulation once again. This continuous cycle enables the body's cells to receive the necessary oxygen and nutrients for proper functioning while disposing of waste products.

Perfusion, in medical terms, refers to the process of circulating blood through the body's organs and tissues to deliver oxygen and nutrients and remove waste products. It is a measure of the delivery of adequate blood flow to specific areas or tissues in the body. Perfusion can be assessed using various methods, including imaging techniques like computed tomography (CT) scans, magnetic resonance imaging (MRI), and perfusion scintigraphy.

Perfusion is critical for maintaining proper organ function and overall health. When perfusion is impaired or inadequate, it can lead to tissue hypoxia, acidosis, and cell death, which can result in organ dysfunction or failure. Conditions that can affect perfusion include cardiovascular disease, shock, trauma, and certain surgical procedures.

Heme proteins are a type of protein that contain a heme group, which is a prosthetic group composed of an iron atom contained in the center of a large organic ring called a porphyrin. The heme group gives these proteins their characteristic red color. Hemeproteins have various important functions in biological systems, including oxygen transport (e.g., hemoglobin), electron transfer (e.g., cytochromes), and enzymatic catalysis (e.g., peroxidases and catalases). The heme group can bind and release gases, such as oxygen and carbon monoxide, and can participate in redox reactions due to the ease with which iron can change its oxidation state.

Resuscitation is a medical term that refers to the process of reversing cardiopulmonary arrest or preventing further deterioration of someone in cardiac or respiratory arrest. It involves a series of interventions aimed at restoring spontaneous blood circulation and breathing, thereby preventing or minimizing tissue damage due to lack of oxygen.

The most common form of resuscitation is cardiopulmonary resuscitation (CPR), which combines chest compressions to manually pump blood through the body with rescue breaths to provide oxygen to the lungs. In a hospital setting, more advanced techniques such as defibrillation, medication administration, and intubation may also be used as part of the resuscitation process.

The goal of resuscitation is to stabilize the patient's condition and prevent further harm while treating the underlying cause of the arrest. Successful resuscitation can lead to a full recovery or, in some cases, result in varying degrees of neurological impairment depending on the severity and duration of the cardiac or respiratory arrest.

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... (18 O, Ω) is a natural, stable isotope of oxygen and one of the environmental isotopes. 18 O is an important ... In the study of plants' photorespiration, the labeling of atmosphere by oxygen-18 allows for the measurement of oxygen uptake ... Large amounts of oxygen-18 enriched water are used in positron emission tomography centers, for on-site production of 18F- ... In the 1950s, Harold Urey performed an experiment in which he mixed both normal water and water with oxygen-18 in a barrel, and ...
An oxygen mask provides a method to transfer breathing oxygen gas from a storage tank to the lungs. Oxygen masks may cover only ... These special oxygen bottles are filled with oxygen at a very high pressure which provides a longer time duration of oxygen for ... Oxygen helmets are often preferred for oxygen administration in hyperbaric oxygen chambers for children and patients that are ... Because they seal tightly, pressure-demand-type oxygen masks are also used in hyperbaric oxygen chambers and for oxygen ...
... is a physiological term for oxygen uptake per heartbeat at rest. Åstrand et al., "Textbook of Work Physiology", ...
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... based oxygen plants is the low cost of oxygen produced in the cases where there are no rigid requirements to the product oxygen ... Where gaseous oxygen purity is required at the level of 90-95% with the capacity of up to 5,000 Nm3 per hour, adsorption oxygen ... The adsorption oxygen plants produce 5 to 5,000 normal cubic meters per hour of oxygen with a purity of 93-95%. These systems, ... Oxygen plants are industrial systems designed to generate oxygen. They typically use air as a feedstock and separate it from ...
... may refer to: Oxygenation index in medicine In chemistry, the ratio of oxygen (atoms) over hydrogen in a ... used in a Van Krevelen diagram Limiting oxygen index This disambiguation page lists articles associated with the title Oxygen ...
The Oxygen architecture is to consist of handheld terminals, computers embedded in the environment, and dynamically configured ... MIT Project Oxygen v t e (Massachusetts Institute of Technology, Usability, All stub articles, Computing stubs). ... Project Oxygen is a research project at the Massachusetts Institute of Technology's Computer Science and Artificial ... Project Oxygen: Pervasive, Human-Centric Computing-An Initial Experience, Larry Rudolph, pp. 1-12, in Advanced Information ...
... forms at normal atmospheric pressure at a temperature below 54.36 K (−218.79 °C, −361.82 °F). Solid oxygen O2, ... It was found that a metallic ζ-phase appears at 96 GPa when ε-phase oxygen is further compressed. As the pressure of oxygen at ... A ζ-phase appears at 96 GPa when ε-phase oxygen is further compressed. This phase was discovered in 1990 by pressurizing oxygen ... See also: For papers dealing with the magnetic properties of solid oxygen we refer to magnetisation of condensed oxygen under ...
A molecule is said to have a positive oxygen balance if it contains more oxygen than is needed and a negative oxygen balance if ... Ammonium nitrate has an oxygen balance of +20% and TNT has an oxygen balance of −74%, so it would appear that the mixture ... For example, TNT is an oxygen negative explosive and is commonly mixed with oxygen positive energetic materials or fuels to ... Explosives with negative or positive oxygen balance are commonly mixed with other energetic materials that are either oxygen ...
... of performance art pieces which Anna Oxygen is involved Discographies Anna Oxygen at AllMusic Anna Huff at AllMusic Anna Oxygen ... As Anna Oxygen, she composed the album herself, handling primary vocals and sequencing. It featured guest artists such as Kitty ... Anna Oxygen at AllMusic Phares, Heather (February 21, 2006). "This Is an Exercise Review". AllMusic. Retrieved 2014-12-30. ... "Anna Oxygen Biography". annaoxygen.com/. Archived from the original on 2015-01-20. Retrieved 2015-01-01. Myers, Holly (November ...
Oxygen is a chemical element with symbol O and atomic number 8. Oxygen may also refer to: Oxygen XML Editor Oxygen Games, a ... 2014 Oxygen (Swans EP) or the title song, 2014 Oxygen, an EP by Austin Mahone, 2018 "Oxygen" (Hadouken! song), 2010 "Oxygen" ( ... "Oxygen", by Hoku from Hoku, 2000 "Oxygen", by Jesse McCartney from Departure, 2008 "Oxygen", by JJ72 from JJ72, 2000 "Oxygen", ... "Oxygen", by Zion I from Break a Dawn, 2006 Bottled oxygen (climbing), oxygen use in mountaineering Oxygen (horse) (1828-1854/ ...
Oxygen's Oaks was the last of twenty classic wins for her owner George FitzRoy, 4th Duke of Grafton. Oxygen was regarded the ... Weatherby (1857). "Oxygen". The General Stud Book. 6: 144. hdl:2027/coo.31924066667092. "Oxygen pedigree". equineline.com. 2012 ... leaving Oxygen to walk over the course to claim the prize money. Three days later in the 1000 Guineas Oxygen was made the ... at least a stone inferior to Oxygen at her best. On 20 May Oxygen started at odds of 12/1 for the Oaks Stakes over one and a ...
... is the busiest area of the metropolis. The "Satata Bus" run for students in the city plies from this place to ... Oxygen Square (Bengali: অক্সিজেন মোড়) is a place in Chittagong, Bangladesh. It is an urban square under Bayazid Thana. It is ... The only highway to Rangamati is N106 which is accessed from Oxygen Square. The distance from here to Muradpur Circle is 3km. ... Bangabandhu Avenue in Chittagong extends from Oxygen Square to Kuais. This place is essential for road communication in the ...
... oxygen concentrator and inhaled through a nasal cannula for up to about 20 minutes. The machines used by oxygen bars or oxygen ... dollar per minute to inhale a percentage of oxygen greater than the normal atmospheric content of 20.9% oxygen. This oxygen is ... An oxygen bar is an establishment, or part of one, that sells oxygen for recreational use. Individual scents may be added to ... Oxygen may also cause serious side effects at excessive doses. Although the effects of oxygen toxicity at atmospheric pressure ...
OXYGEN A new play, 'Oxygen' was authored by Roald Hoffman, Professor of Chemistry at Cornell who received the chemistry Nobel ... in Oxygen, he and Roald Hoffmann dramatize the events leading to the discovery of oxygen in the... v t e (2001 plays, All stub ... Oxygen is a 2001 play by Roald Hoffman who received the chemistry Nobel prize in 1982, and Carl Djerassi, the Stanford ... The play is a dramatisation of events leading to the discovery of oxygen in the eighteenth century. Robert C. Roach, Peter D. ...
Most home oxygen fires are caused by patients smoking whilst using medical oxygen. Other sources of naked flames, such as gas ... Oxygen firebreaks are fitted into the oxygen delivery tubing close to the patient, typically around the patient's sternum where ... The man was under oxygen therapy due to respiratory problems, and his attempt to light up a cigarette caused the oxygen tank to ... "Home Oxygen Fire Prevalence in England (2013-17)" (PDF). www.firebreaks.info. BPR Medical. Retrieved 22 July 2019. "Home Oxygen ...
... leaving an oxygen-enriched gas for use by people requiring medical oxygen due to low oxygen levels in their blood. Oxygen ... The term, oxygen generator, is a misnomer in that the oxygen is not generated as it is with a chemical oxygen generator, but ... Non-medical oxygen concentrators can be used as feed gas to a medical oxygen system, such as the oxygen system in a hospital, ... Industrial oxygen concentrators are sometimes referred to as oxygen generators within the oxygen and ozone industries to ...
... (stylized in all capitals as OXYGEN:INHALE) is the seventh studio album by Canadian rock band Thousand Foot ... "Oxygen:Inhale" Review". "Thousand Foot Krutch - "Oxygen: Inhale" / Sort Music Россия". Archived from the original on October 22 ... "Thousand Foot Krutch: Oxygen: Inhale on PledgeMusic". PledgeMusic. Archived from the original on January 10, 2016. Retrieved ... "THOUSAND FOOT KRUTCH LAUNCHES FIRST RADIO SINGLE FROM OXYGEN: INHALE, "BORN THIS WAY" GOES FOR ADDS JULY 22". Jesus Freak ...
... is an alternative rock/pop band formed in Kansas City and currently based in Los Angeles. The band is composed of ... Black Oxygen released the EP City of Angels in 2018, which included the track "Rockstar", a Post Malone cover. In 2019, the ... Black Oxygen was formed in Kansas City by David Lyle (vocals, guitar) and his brother Nick (drums, keyboards). In 2010, they ... In 2016, Black Oxygen released a single and music video for "Whole Thang", a song featuring rappers Kstylis and Kutt Calhoun. ...
Since the late 1990s the recreational use of oxygen has been promoted by oxygen bars, where customers breathe oxygen through a ... Higher than normal concentrations of oxygen lead to increased levels of reactive oxygen species. Oxygen is necessary for cell ... Divers who breathe oxygen fractions greater than of air (21%) need to be educated on the dangers of oxygen toxicity and how to ... Oxygen toxicity is managed by reducing the exposure to increased oxygen levels. Studies show that, in the long term, a robust ...
The NIST webbook on oxygen Photochemistry & Photobiology tutorial on Singlet Oxygen Demonstration of the Red Singlet Oxygen ... Various methods for the production of singlet oxygen exist. Irradiation of oxygen gas in the presence of an organic dye as a ... Unlike ground state oxygen, singlet oxygen participates in Diels-Alder [4+2]- and [2+2]-cycloaddition reactions and formal ... In mammalian biology, singlet oxygen is one of the reactive oxygen species, which is linked to oxidation of LDL cholesterol and ...
... , 3O2, refers to the S = 1 electronic ground state of molecular oxygen (dioxygen). Molecules of triplet oxygen ... Under a molecular orbital theory framework, the oxygen-oxygen bond in triplet dioxygen is better described as one full σ bond ... metastable singlet oxygen. Because the molecule in its ground state has a non-zero spin magnetic moment, oxygen is paramagnetic ... Triplet oxygen will, however, readily react with molecules in a doublet state to form a new radical. Conservation of spin ...
... compares the relative amount of oxygen available for respiration at a variable pressure to that available at ... It does so by expressing oxygen concentration as a ratio of the partial pressure of oxygen at a given altitude or pressure to ... Calculations occur as follows: Let O2E be oxygen equivalent, FO2 be the fractional concentration of oxygen, Patm (generally 760 ... oxygen equivalent may aid in recognizing and managing variable oxygen availability during procedures such as hyperbaric oxygen ...
Later, researches suggested adding the oxygen foam into food or drink. Such oxygen-enriched drinks received the name "oxygen ... Adaptogen Hydrogen peroxide therapy Hypoxia (medical) Oxygen therapy Oxygen concentrator Oxygen bar Nitro cold brew coffee ... The oxygen cocktail is a foamy substance containing a beverage drink (juice, milk, etc.) enriched in gaseous oxygen. The drink ... An essential element of the oxygen cocktail is the foaming agent, such as gelatin egg white or liquorice. Initially, oxygen ...
Use of 100% oxygen is limited by oxygen toxicity at deeper depths. Convulsions are more likely when the PO2 exceeds 1.6 bar ( ... In other words, the larger oxygen window due to a higher oxygen partial pressure can allow the diver to decompress faster at a ... It is caused by metabolic consumption of oxygen. The term "oxygen window" was first used by Albert R. Behnke in 1967. Behnke ... In diving and decompression, the oxygen window is the difference between the partial pressure of oxygen (PO2) in arterial blood ...
... was used in the first liquid fueled rocket. The World War II V-2 missile also used liquid oxygen under the name A ... Liquid oxygen is obtained from the oxygen found naturally in air by fractional distillation in a cryogenic air separation plant ... Liquid oxygen is also a very powerful oxidizing agent: organic materials will burn rapidly and energetically in liquid oxygen. ... "Liquid Oxygen Receipt, Handling, Storage and Disposal". USAF Training Film. Lewis, Gilbert N. (1924). "The Magnetism of Oxygen ...
... (also known as Oxygen) are a cluster of three individual but interlinked residential towers in Manchester, ... "Oxygen Towers". Skyscraper Center. Retrieved 5 March 2023. "PAG's £85m Oxygen tops out". Place North West. 28 July 2020. ... "Oxygen, Manchester". 5plus Architects. Retrieved 5 March 2023. "Oxygen reaches peak". Place North West. 3 December 2019. ... Oxygen Towers includes a spa with 25 m (82 ft) pool, a gym, spin and yoga studio, cinema room, and residents' lounge. List of ...
If you are using oxygen in your home, you must take extra care to stay safe from fires ... If you are using oxygen in your home, you must take extra care to stay safe from fires ... Oxygen makes things burn much faster. Think of what happens when you blow into a fire; it makes the flame bigger. ... Oxygen makes things burn much faster. Think of what happens when you blow into a fire; it makes the flame bigger. ...
Hyperbaric oxygen therapy increased cerebral blood flow and improved cognition in a small study of older adults with memory ... Hyperbaric oxygen therapy (HBOT) increases cerebral blood flow and improves cognitive performance in older adults with memory ... Harch is the owner of Harch Hyperbaric Oxygen Therapy, Inc. Edelmayer has disclosed no relevant financial relationships. ... Cite this: Hyperbaric Oxygen Therapy for Alzheimers Prevention? - Medscape - Sep 21, 2021. ...
... oxygen while under increased atmospheric pressure. HBOT is a treatment that can be traced back to the 1600s. ... What is hyperbaric oxygen therapy (HBOT)?. What is the role of oxygen chambers in the delivery of hyperbaric oxygen therapy ( ... Oxygen as an antibiotic. The effect of inspired oxygen on infection. Arch Surg. 1984 Feb. 119(2):199-204. [QxMD MEDLINE Link]. ... A cumulative oxygen debt is the time integral of the volume of oxygen consumption (VO2) measured during and after shock insult ...
... a lack of oxygen Limiting oxygen concentration Oxygen compounds Oxygen plant Oxygen sensor Portals: Chemistry Medicine Oxygen ... Oxygen Oxygen (O2) Properties, Uses, Applications Roald Hoffmann article on "The Story of O" WebElements.com - Oxygen Oxygen on ... Oxygen tents were once commonly used in oxygen supplementation, but have since been replaced mostly by the use of oxygen masks ... Oxygen, as a mild euphoric, has a history of recreational use in oxygen bars and in sports. Oxygen bars are establishments ...
Future Mars colonists are going to need oxygen, and NASA has a plan to make it. Their Mars 2020 Rover will be equipped... ... Stunning prefab OxyGen project will deliver a green oasis to Paris. *Lucy Wang ... Scientists found oxygen in a galaxy 13.1 billion light years away. *Lacy Cooke ... Earths oxygen levels are declining - and scientists arent sure why. *Lacy Cooke ...
Oxygen candle[edit]. A chlorate candle, or an oxygen candle, is a cylindrical chemical oxygen generator that contains a mix of ... Device that releases oxygen via a chemical reaction. A chemical oxygen generator is a device that releases oxygen via a ... also known as oxygen bottles. In narrow body airliners, for each row of seats there were overhead oxygen masks and oxygen ... The oxygen source is usually an inorganic superoxide,[1] chlorate, or perchlorate; ozonides are a promising group of oxygen ...
Science News was founded in 1921 as an independent, nonprofit source of accurate information on the latest news of science, medicine and technology. Today, our mission remains the same: to empower people to evaluate the news and the world around them. It is published by the Society for Science, a nonprofit 501(c)(3) membership organization dedicated to public engagement in scientific research and education (EIN 53-0196483).. ...
How did oxygen get in the US?. Plants turn carbon into oxygen. ... Is gold reactive to oxygen?. Yes, gold can react with oxygen to ... Is there oxygen in gold?. Type your answer here... No, there is no xygen in gold. If there were, we could breath through gold. ... Can a lot of oxygen gas be pumped into a very small container and why? What is the name of the ionic compound LiI? Where are ... Its like saying oxygen will turn into carbon (assuming we arent talking about supernovas, of course) ...
Oxygen, an international, peer-reviewed Open Access journal. ...
... Category: Painting & Plastering. Key contact details for Oxygen Design Mobile. 0438 172 441 Email. Email ... Oxygen Designs Keywords. Painting , Logo Design , Brochures , Airbrushing , Concept Sketches , Oxygen Design , Marker ... Is Oxygen Design in Australia your business?. Claim your listing and attract more leads by adding more content, photos and ...
... and what happens when low-oxygen areas form. ... Learn how much oxygen the Bays living creatures need to ... How does oxygen get into the water?. Oxygen can get into the water in several ways:. *Oxygen from the atmosphere dissolves and ... How do low-oxygen areas form?. Hypoxic, or low-oxygen, areas are regions with less than 2 mg/L of dissolved oxygen. Anoxic, or ... Dissolved Oxygen. Learn how much oxygen the Bays living creatures need to survive, and what happens when low-oxygen areas form ...
Oxygen bleach You can buy oxygen bleach at stores and online. Youll find Stain Solver at my website, askthebuilder.com (type " ... Once my tile and grout were clean with the oxygen bleach, I discovered a way to keep them looking that way. I decided to use ... Not only does oxygen bleach do this on wood decks, it works on anything thats water washable. ... I interviewed a chemist who mentioned oxygen bleach. This comes in powder form, and when its mixed with water, billions of ...
Watch full episodes of Oxygen true crime shows including Snapped, Killer Couples, and Three Days to Live. Visit Crime Time for ... Become an Oxygen Insider. Get an all-access pass to never-before-seen content, free digital evidence kits, and much more! ... Oxygen Insider Exclusives. Check out never-before-seen content, free digital evidence kits, and much more! ...
Tagged automobile, car, climate, energy, fuel, fuel cell, green car, green energy, hydrogen, Mirai, oxygen, smart car, Toyota ... This process introduced oxygen vacancies on the surface of the material, allowing for a huge boost to the amount of energy ... Controlling Oxygen Activity for Better Batteries. Posted on July 7, 2016 by Amanda Staller ... "With this study, we want to open a new pathway to explore more battery materials in which we can control oxygen activity." ...
Stepwise Disintegration of the Photosynthetic Oxygen-Evolving Complex. *Mark. Tommos, Cecilia ; McCracken, John ; Styring, ... we have examined the YZ site and its status with respect to solvent exposure under varying degrees of disassembly of the oxygen ... we have examined the YZ site and its status with respect to solvent exposure under varying degrees of disassembly of the oxygen ... Stepwise Disintegration of the Photosynthetic Oxygen-Evolving Complex}}, url = {{http://dx.doi.org/10.1021/ja980281z}}, doi ...
Use this page to view details for the Local Coverage Article for oxygen and oxygen equipment - policy article. ... The following oxygen and oxygen equipment HCPCS codes for individual items are included in the functionality of code E0467:. * ... Oxygen services furnished by an airline to a beneficiary are non-covered. Payment for oxygen furnished by an airline is the ... Claims for oxygen contents and/or oxygen accessories should not be submitted in situations in which they are not separately ...
Demand estimation and recommendations to plan oxygen delivery from source to patient. ... the Oxygen System Planning Tool recommends an oxygen source to meet those needs (i.e. a new local oxygen plant, liquid oxygen, ... Oxygen Plant-in-a-Box The Oxygen Plant-in-a-Box package includes everything needed to produce large volumes of oxygen. Plants ... Resilient Oxygen Concentrators The Resilient Oxygen Concentrator project aims to develop a durable, state-of-the-art oxygen ...
I like oxygen. I breathe in my share every day. Nevertheless I remain skeptical of new products designed to put more oxygen ... With a surplus of oxygen in the lungs, the carbon dioxide cant leave the body. Worse, the build up of oxygen in the lungs can ... Now, if we assume that humans absorb oxygen efficiently through their gut, which they dont, and if the dissolved oxygen in the ... Unfortunately the world of alternative medicine has painted a scenario in which the human body is oxygen-deprived. More oxygen ...
With no dissolved oxygen to sustain animals or plants, ocean anoxic zones are areas where only microbes suited to the ... With no dissolved oxygen to sustain animals or plants, ocean anoxic zones are areas where only microbes suited to the ... In oxygen-rich oceans, carbon is moved around largely by food web processes that begin with carbon dioxide-fixing phytoplankton ... "What happens to our carbon cycle as we get these large areas of the ocean that are oxygen-free?" she said. This question was ...
Aircraft Spruce is a worldwide distributor of certified and homebuilt aircraft supplies.
Researchers zeroed in on a key step of photosynthetic oxygen production. What they learned brings them one step closer to ... During photosynthesis, the oxygen-evolving complex, a cluster of four manganese atoms and one calcium atom connected by oxygen ... This water molecule likely provides one of the oxygen atoms in the oxygen molecule produced at the end of the cycle. ... including the elusive transient state at the end that bonds two oxygen atoms from two water molecules to form the oxygen ...
Oxygen India must breath we must use our greatest resource for mobilization Americas military on a humanitarian mission.Other ... Oxygen India must breath we must use our greatest resource for mobilization Americas military on a humanitarian mission.Other ...
All Oxygen Concentrators must come with an invoice indicating the value regardless if it was obtained free or at a discounted ... Oxygen concentrators are available in different types and are made of different components, some of which may be classified as ... As such, the demand for life-saving oxygen concentrators in India has gone up in order to cater to the growing need. Singapore ... Although India stands as one of the leading oxygen-producers in the world, producing over 7000 tons a day, most of its plants ...
Find out what to expect if your premature or sick baby needs to go home from the neonatal unit on oxygen. ... You will need to have a supply of portable oxygen to do this. Portable oxygen is prescribed with the oxygen supply requested ... Some oxygen suppliers will also contact the Fire and Rescue service to tell them that you are using home oxygen. The Fire and ... All oxygen equipment is supplied by one of four suppliers depending on where you live in the UK. The oxygen supplier is ...
Oxygen generators: This item is not permitted in carry-on baggage and it is not permitted in checked baggage. ...
eukaryotes, oxygen, oxygen levels (and multicellular life). Claim: Complex cells started without oxygen. Denyse OLeary. May 1 ... arsenic, oxygen, stromatolites. Did microbes once thrive in arsenic world - a world without oxygen?. Denyse OLeary. October 2 ... oxygen. Planets with oxygen not necessarily good candidates for ET life?. Denyse OLeary. December 17, 2018. Extraterrestrial ... early Earth, oxygen. Researchers: Earths oxygen rose and fell several times before the Great Oxidation Event 2.2 bya. Denyse ...
Thread-topic: [cross-project-issues-dev] Oxygen.1 and JDK9. , We looked at what you suggest, but found that it might be ... Re: [cross-project-issues-dev] Oxygen.1 and JDK9 *From: Daniel Megert ... Re: [cross-project-issues-dev] Oxygen.1 and JDK9 *From: Jens Reimann ... Re: [cross-project-issues-dev] Oxygen.1 and JDK9 *From: Martin Lippert ...
The research team has discovered a new isotope of Oxygen, known as 28O. ...
There are many many reasons to be concerned…but a risk to the worlds oxygen supply is not one of them, Allison Mills from ... "Amazonia is not a big source of oxygen because trees respire, just like animals. Trees use up most of the oxygen that they ... put a figure on the Amazons oxygen production, estimating that the forest consumes and emits about 32 gigatons of oxygen per ... How Much Oxygen Does the Amazon Rain Forest Provide?. By Aristos Georgiou On 8/27/19 at 7:26 AM EDT. ...
  • Oxygen is Earth's most abundant element, and after hydrogen and helium, it is the third-most abundant element in the universe. (wikipedia.org)
  • Diatomic oxygen gas currently constitutes 20.95% of the Earth's atmosphere, though this has changed considerably over long periods of time. (wikipedia.org)
  • Oxygen makes up almost half of the Earth's crust in the form of oxides. (wikipedia.org)
  • Oxygen is continuously replenished in Earth's atmosphere by photosynthesis, which uses the energy of sunlight to produce oxygen from water and carbon dioxide. (wikipedia.org)
  • According to the latest research, we learn from ScienceDaily: Earth's oxygen levels rose and fell more than once hundreds of millions of years before the planetwide success of the Great Oxidation Event about 2.4 billion years ago, new research from the University of Washington shows. (uncommondescent.com)
  • The evidence comes from a new study that indicates a second and much earlier "whiff" of oxygen in Earth's distant past - in the atmosphere and on the surface of a large stretch of ocean - showing that the oxygenation of the Earth was a complex process of repeated trying and failing over a vast stretch of time. (uncommondescent.com)
  • But even if the Amazon has a very small effect on the overall level of oxygen in the Earth's atmosphere, can can we still estimate how much it produces? (newsweek.com)
  • Scientists led by Daniel Stolper at Princeton University studied samples of ancient air trapped in ice in Antarctica and Greenland and made a startling discovery - for the past 800,000 years, the Earth's oxygen levels have steadily decreased. (inhabitat.com)
  • The ancient ice-trapped air reveals oxygen levels in Earth's atmosphere have gone down by 0.7 percent over 800,000 years, which fortunately isn't dire. (inhabitat.com)
  • The presence of arsenides demonstrates that the formation of serpentinite during the early stages of subduction, by the interaction of water with olivine (the major mineral in the Earth's mantle), massively consumes oxygen. (esrf.fr)
  • Almost all of the oxygen in Earth's atmosphere for the last 2 and a half billion years came from photosynthesis. (space.com)
  • This diagram shows how the solar wind and Earth's magnetic field funnel oxygen ions from Earth to the moon. (space.com)
  • The ions get out of the Earth's atmosphere because when sunlight or the occasional cosmic ray hits atoms of oxygen (or any other gas) at the edge of space, those atoms can lose an electron, becoming charged. (space.com)
  • Earth's upper atmosphere and the moon have relatively little oxygen-16, whereas the solar wind has more. (space.com)
  • Another is poor in oxygen-16, and it wasn't clear where that came from, until the team looked at the data and compared this component to the ions in Earth's atmosphere . (space.com)
  • All plants, animals, and fungi need oxygen for cellular respiration, which extracts energy by the reaction of oxygen with molecules derived from food and produces carbon dioxide as a waste product. (wikipedia.org)
  • In tetrapods breathing brings oxygen into the lungs where gas exchange takes place, carbon dioxide diffuses out of the blood, and oxygen diffuses into the blood. (wikipedia.org)
  • Plants turn carbon into oxygen. (answers.com)
  • Cathode particles treated with the carbon dioxide-based mixture show oxygen vacancies on the surface. (electrochem.org)
  • It's impossible to shuttle oxygen tanks out and the air recycling systems are only about 50 percent efficient when it comes to recovering oxygen from carbon dioxide - but now a new development could mean easy breathing in space. (electrochem.org)
  • The original paper, " A selective and efficient electrocatalyst for carbon dioxide reduction ," detailed a development from scientists at the University of Delaware of a silver electrocatalyst that, due to its nanoscale structure, could convert carbon dioxide to carbon monoxide with 92 percent efficiency - freeing the oxygen in the process. (electrochem.org)
  • Deep in the lungs, tiny and fragile sacs called alveoli are the site where inhaled oxygen enters the bloodstream and carbon dioxide leaves to be exhaled. (livescience.com)
  • With a surplus of oxygen in the lungs, the carbon dioxide can't leave the body. (livescience.com)
  • What happens to our carbon cycle as we get these large areas of the ocean that are oxygen-free? (countercurrents.org)
  • In oxygen-rich oceans, carbon is moved around largely by food web processes that begin with carbon dioxide-fixing phytoplankton that photosynthesize at the water's surface. (countercurrents.org)
  • In fact, sediments under these anoxic zones generally have more organic carbon deposits than their oxygen-rich counterparts. (countercurrents.org)
  • In photosynthesis, plants capture and store solar energy, using it to convert carbon dioxide in the air into sugar molecules which they use for food, producing oxygen as a byproduct. (newsweek.com)
  • There is a net release of oxygen while the tree is growing and storing carbon in its wood, but when the tree dies the wood rots, removing the same amount of oxygen from the air to form carbon dioxide (CO2) from the carbon in the wood," he said. (newsweek.com)
  • A net release of oxygen occurs only if the carbon sequestered through photosynthesis is buried in a place where it cannot combine with oxygen to form CO2. (newsweek.com)
  • Carbon and pyrite are two substances that may be behind oxygen levels declining. (inhabitat.com)
  • Colder soda contains that carbon dioxide, and perhaps the cool oceans are now holding more dissolved oxygen in a similar manner. (inhabitat.com)
  • While Earth has a blue sky, oceans of liquid water brimming with life, and an oxygen-rich atmosphere, Venus is surrounded by dense cloud cover and an atmosphere comprising carbon dioxide, nitrogen and various trace gases. (dlr.de)
  • This layer is produced by ultraviolet radiation from the Sun, which breaks down the carbon dioxide and carbon monoxide in Venus' atmosphere into atomic oxygen and other products. (dlr.de)
  • The effectiveness of this process is facilitated through tissue perfusion, a measure of the exchange of oxygen and carbon dioxide within the body's tissues. (hermanmiller.com)
  • See figure 1 / This results in compressed soft tissues, reduced blood supply, and less exchange of oxygen and carbon dioxide within the cells. (hermanmiller.com)
  • It can take about three minutes for this exchange to clear out all the carbon dioxide and replace it with fresh oxygen. (hermanmiller.com)
  • These fascinating "redox factories" scavenge or release water, oxygen, hydrogen, sulfur and carbon, depending on the element's oxidation state. (esrf.fr)
  • While it has relatively large amounts of carbon, nitrogen, and oxygen -- approximately 10, 8, and 3 percent of the abundances measured in the Sun -- other elements like calcium and iron have abundances around one millionth that of the Sun. (sciencedaily.com)
  • Only a few such stars are known in the halo of our galaxy, but none have such an enormous amount of carbon, nitrogen, and oxygen compared to their iron content," said David Aguado, a postdoctoral researcher at the University of Cambridge and co-author of the study. (sciencedaily.com)
  • This technique, used commonly with products such as meat, uses inert gases such as nitrogen and carbon dioxide, which are flushed through the package to reduce the oxygen concentration. (foodnavigator.com)
  • Many major classes of organic molecules in living organisms contain oxygen atoms, such as proteins, nucleic acids, carbohydrates, and fats, as do the major constituent inorganic compounds of animal shells, teeth, and bone. (wikipedia.org)
  • Now, the team has used the same method to zero in on a key step in which a water molecule moves in to bridge manganese and calcium atoms in the catalytic complex that splits water to produce breathable oxygen. (sciencedaily.com)
  • During photosynthesis, the oxygen-evolving complex, a cluster of four manganese atoms and one calcium atom connected by oxygen atoms, cycles through four stable oxidation states, known as S0 through S3, when exposed to sunlight. (sciencedaily.com)
  • This water molecule likely provides one of the oxygen atoms in the oxygen molecule produced at the end of the cycle. (sciencedaily.com)
  • In November 2021, the extremely reactive oxygen atoms in the atmosphere of Venus were detected directly for the first time. (dlr.de)
  • In November 2021, researchers from the DLR Institute of Optical Sensor Systems , the Max Planck Institute for Radio Astronomy and the University of Cologne succeeded in directly detecting the extremely reactive oxygen atoms in the atmosphere of Venus for the first time. (dlr.de)
  • Neutral oxygen atoms have eight protons and eight electrons. (space.com)
  • Oxygen atoms from Earth usually lose only one electron (and are noted as O+). (space.com)
  • Humans use their lungs to inhale oxygen from the air. (chesapeakebay.net)
  • Blood cells, on exiting the lungs, are nearly saturated with about 97 percent oxygen bound molecularly to hemoglobin. (livescience.com)
  • Worse, the build up of oxygen in the lungs can collapse the alveoli and cause permanent lung damage. (livescience.com)
  • Your baby may need home oxygen because their lungs are not working well enough for them to get enough oxygen from the air. (bliss.org.uk)
  • Some injuries or illness make it hard for oxygen to pass from your lungs to the blood. (denverhealth.org)
  • Oxygen therapy increase the amount of oxygen in your lungs. (denverhealth.org)
  • Your blood oxygen level represents the percentage of oxygen your red blood cells carry from your lungs to the rest of your body. (apple.com)
  • Hyperbaric Oxygen Therapy for Alzheimer's Prevention? (medscape.com)
  • Hyperbaric oxygen therapy (HBOT) increases cerebral blood flow and improves cognitive performance in older adults with memory problems, early research suggests. (medscape.com)
  • Harch is the owner of Harch Hyperbaric Oxygen Therapy, Inc. Edelmayer has disclosed no relevant financial relationships. (medscape.com)
  • Hyperbaric oxygen therapy (HBOT) is breathing 100% oxygen while under increased atmospheric pressure. (medscape.com)
  • Algae and underwater grasses release oxygen during photosynthesis. (chesapeakebay.net)
  • Trees use up most of the oxygen that they produce though photosynthesis. (newsweek.com)
  • Essentially, this means that the net effect of the Amazon rain forest on the amount of oxygen in the global atmosphere is "virtually nothing," since the photosynthesis to produce new plant matter is (almost) balanced by microbes decomposing dead plant material, according to Saleska. (newsweek.com)
  • Saleska says that tropical vegetation is responsible for about 25 percent of the oxygen that is produced by photosynthesis on land, via trees, shrubs, grasses and other plants. (newsweek.com)
  • The Amazon is, generously, half of the tropics-and certainly somewhat less-so that means, at most, 12 percent of the oxygen produced each year from land photosynthesis comes from the rain forest. (newsweek.com)
  • So, at most, 6 percent of the oxygen from photosynthesis comes from the Amazon," Saleska said. (newsweek.com)
  • Keep in mind that even the gross flows of oxygen from photosynthesis are very small, compared to the very large amount of oxygen in the atmosphere. (newsweek.com)
  • Dissolved oxygen (DO) is the amount of oxygen that is present in the water. (chesapeakebay.net)
  • However, the amount of oxygen an animal needs varies depending on how large or complex the animal is and where it lives. (chesapeakebay.net)
  • Temperature limits the amount of oxygen that can dissolve in water: water can hold more oxygen during winter than during the hot summer months. (chesapeakebay.net)
  • They will also write a HOOF prescription for the amount of oxygen your baby will need. (bliss.org.uk)
  • The amount of oxygen in the atmosphere is 20.95 percent, and it is not changing very much," he said. (newsweek.com)
  • From this perspective, the Amazon could burn up and blow away and the amount of oxygen in the atmosphere would not be much affected-CO2 is another story though. (newsweek.com)
  • The figures for this time period only include 13 out of the EA's 14 operating areas, and data isn't yet available for 2023, meaning that while there were at least 99 emergency oxygen deployments in the past five years, the true figure is likely to be higher. (newscientist.com)
  • In 2020-21, the Ghana Ministry of Health piloted the UNICEF Oxygen System Planning Tool to quantify oxygen need in the Eastern Region, across all levels of the health system. (unicef.org)
  • Adults with emphysema, chronic asthma or chronic bronchitis, in particular, will stop breathing if they inhale pure oxygen for too long. (livescience.com)
  • Breathing pure oxygen creates an abundance of free radicals. (livescience.com)
  • For a few dollars per minute, you can breathe in pure oxygen through a mask or tubes, for that oh-so-sexy emphysema-sufferer look. (livescience.com)
  • When exposed to a spark or an open flame, pure oxygen can significantly speed up the combustion of porous materials such as clothing, textiles, and rubber. (lu.se)
  • It safely delivers 99% pure oxygen in all positions, including in harsh environments. (safran-group.com)
  • Added another trainee, Mr Ahmed Ali, a maintenance technician: "We learned the sophisticated process of extracting oxygen from nature, mastering the techniques of filtration and purification to fill cylinders with pure oxygen. (who.int)
  • Medical oxygen safety tip sheet. (medlineplus.gov)
  • Cylinder capacity: 5 litres, Working pressure PW: 200 bar, Test pressure PH: 300 bar, Equipped with a 3/4" valve, The cylinder is filled with medical oxygen: 1,06 m3, It is certified and validly. (dotmed.com)
  • This impactful project has involved a series of crucial activities, including provision of electric generators, construction of structure for oxygen station equipment, procurement and installation of oxygen plants, implementation of an oxygen network piping system to distribute medical oxygen to the wards in each hospital, and training of 21 skilled technical workers. (who.int)
  • The oxygen stations are now playing a vital role in supplying medical oxygen to the hospitals, ensuring a lifeline for those in critical need. (who.int)
  • Oxygen from the atmosphere dissolves and mixes into the water's surface. (chesapeakebay.net)
  • The human body has adapted quite well to this lower atmosphere of ours that is roughly 21 percent oxygen, 78 percent nitrogen and 1 percent trace gases. (livescience.com)
  • Researchers have found that the presence of oxygen in a planet's atmosphere may not be a strong indicator of life: Simulating in the lab the atmospheres of planets beyond the solar system, researchers successfully created both organic compounds and oxygen, absent of life. (uncommondescent.com)
  • Saleska notes that since 1990, the level of oxygen in the atmosphere has dropped by 0.005 percent-hardly at all. (newsweek.com)
  • One hypothesis is that erosion rates have increased globally, and rocks that are being weathered pull oxygen out of the atmosphere, much like iron binds to oxygen as it rusts. (inhabitat.com)
  • The atomic oxygen in Venus' atmosphere absorbs this radiation. (dlr.de)
  • The concentration of atomic oxygen on both the day and night sides of the venusian atmosphere has now been measured directly for the first time using the 'upgraded German Receiver for Astronomy at Terahertz Frequencies' (upGREAT), a far-infrared spectrometer flown on board the Stratospheric Observatory for Infrared Astronomy (SOFIA). (dlr.de)
  • Astronomers have detected large amounts of oxygen in the atmosphere of one of the oldest and most elementally depleted stars known. (sciencedaily.com)
  • An international team of astronomers from the University of California San Diego, the Instituto de Astrofísica de Canarias (IAC), and the University of Cambridge have detected large amounts of oxygen in the atmosphere of one of the oldest and most elementally depleted stars known -- a "primitive star" scientists call J0815+4729. (sciencedaily.com)
  • The data, which required more than five hours of staring at the star over a single night, were used to measure the abundances of 16 chemical species in the star's atmosphere, including oxygen. (sciencedaily.com)
  • The ink, pattern, and saturation of some tattoos can block light from the sensor, making it difficult for the Blood Oxygen app to get a measurement. (apple.com)
  • Measuring the oxygen saturation is of great value in a wide range of medical fields. (lu.se)
  • Monitoring of cerebral oxygen saturation can be used in the diagnosis of cerebral desaturations in stroke patients. (lu.se)
  • During plastic and reconstructive surgery, the oxygen saturation can be monitored to predict survival of flaps. (lu.se)
  • Several techniques have been developed to monitor oxygen saturation, but they all have limitations. (lu.se)
  • The most well-known technique for measuring oxygen saturation is pulse oximetry that uses the physiologic activity of the cardiac pulse, in combination with the difference in spectroscopic reflectance at wavelength of 660 nm and 940 nm defining the concentration of oxyhemo and deoxyhema, to determine oxygen saturation. (lu.se)
  • PAI thus has the potential of measuring oxygen saturation non-invasively with spatial resolution. (lu.se)
  • To date, PA imaging has mainly been developed for measuring oxygen saturation mainly in phantoms and numerous preclinical studies in animals have exploited the oxygenated and deoxygenated hemoglobin components to characterize tumour microenvironment. (lu.se)
  • In our studies, the feasibility of using PAI for estimating the spatial distribution of oxygen saturation is examined, in models of occlusion reperfusion and adrenalin-dependent vasoconstriction in humans. (lu.se)
  • Tissue oxygen saturation (StO2) is the average blood oxygen saturation in a given section of tissue. (lu.se)
  • A pulse oximeter measures arterial oxygen saturation (SaO2). (lu.se)
  • In-vivo monitoring of tissue oxygen saturation using diffuse reflectance spectroscopy (DRS). Figure: Reistad 2016. (lu.se)
  • In-vivo monitoring of tissue oxygen saturation and distribution using photoacoustic imaging (PAI). (lu.se)
  • In the case of oxygen generation a zeolite-based sieve forces preferential adsorption for nitrogen. (wikipedia.org)
  • In the room and in the cabinet for dipensing liquid nitrogen, there is an oxygen detector for monitoring oxigen level inside and outside the cabinet. (lu.se)
  • When the oxygen level is below 15% the filling of liquid nitrogen stops and the system alarms. (lu.se)
  • However, even at the warmest temperatures seen in the Bay (around 91 degrees Fahrenheit), water is capable of having dissolved oxygen concentrations of 6 to 7 mg/L. So, although high temperatures can influence dissolved oxygen levels, the temperature is not the only cause of low-oxygen areas found in the Bay each summer. (chesapeakebay.net)
  • The findings, published Dec. 11 by the journal ACS Earth and Space Chemistry, serve as a cautionary tale for researchers who suggest the presence of oxygen and organics on distant worlds is evidence of life there. (uncommondescent.com)
  • Once activated for use using photobleaching with UVA radiation, the sensor will turn blue when in the presence of oxygen. (foodnavigator.com)
  • The presence of oxygen in food packaging promotes microbial growth and protein decomposition - leading to food spoilage. (foodnavigator.com)
  • Techniques for establishing the presence of oxygen in packaged foods are already commonplace, but many can be expensive and can require specialist equipment for analysis and trained operators. (foodnavigator.com)
  • Advances in technology have provided industrial oxygen generator systems for use where air is available and a higher concentration of oxygen is desired. (wikipedia.org)
  • upGREAT measured the concentration of atomic oxygen on the day and night side of Venus. (dlr.de)
  • We were able to show that oxygen is formed on the day side of Venus and that its concentration also drops with decreasing solar radiation. (dlr.de)
  • On the night side, a local increase in concentration indicates an enrichment of atomic oxygen as a result of wind currents,' Hübers explains. (dlr.de)
  • A leaking valve or hose in a poorly ventilated room or confined space can quickly increase the oxygen concentration to a dangerous level. (lu.se)
  • But although anoxic oceans may seem alien to organisms like ourselves that breathe oxygen, they're full of life, she said. (countercurrents.org)
  • When people exercise, they need to breathe oxygen to feed the muscle requirements of increasing intensities. (athleticbusiness.com)
  • Researchers from Rice University have discovered an efficient, robust way of drawing hydrogen and oxygen from water. (electrochem.org)
  • The researchers have developed a new catalyst of a cobalt-based thin film, which pumps out hydrogen and oxygen to feed fuel cells. (electrochem.org)
  • Researchers zeroed in on a key step of photosynthetic oxygen production. (sciencedaily.com)
  • The researchers found that a certain kind of oxygen isotope was present in the lunar soil, an isotope that occurs on Earth. (space.com)
  • A highly ionized solar oxygen atom would be unlikely to duplicate the behavior of a singly ionized atom from Earth, the researchers said, because the ion from the solar wind would have to regain some of the electrons that got stripped off. (space.com)
  • When the researchers look deeper down into the sediment, it emerges that periods of oxygen depletion have occurred earlier in the Baltic Sea's history. (lu.se)
  • When researchers from the Department of Geology at Lund University started investigating whether there were other links that could explain variations in oxygen levels, almost ten years ago, they realised that they were facing a complex problem. (lu.se)
  • The researchers speculate on whether this small increase in nutrient supply to the sea - in combination with a gradually warming climate - may even have triggered the oxygen depletion. (lu.se)
  • Most researchers agree that the expansion of the oxygen-depleted seabeds has been accelerated by the eutrophication of the past century. (lu.se)
  • These strange ecosystems are expanding, thanks to climate change - a development that is of concern for fisheries and anyone who relies on oxygen-rich oceans. (countercurrents.org)
  • Colder oceans can hold more dissolved gases, including dissolved oxygen. (inhabitat.com)
  • Down in the depths, the dead seabeds are expanding and research reveals that we have never had such large areas of oxygen depletion in the world's oceans as now. (lu.se)
  • Although in patients with COPD, the approach to daytime hypoxemia using long-term oxygen therapy (LTOT) is established, the best approach to transient nocturnal desaturation varies among clinicians. (nih.gov)
  • A significant proportion (38%) of patients with moderate-to-severe COPD who do not qualify for home oxygen therapy based on their daytime PaO(2) have nocturnal oxygen desaturation without evidence of sleep apnea. (nih.gov)
  • If you are looking to send such devices to Indian hospitals, here's what you need to know about the customs requirements and what to look out for in the particular Oxygen Concentrator you are sending. (dhl.com)
  • During this process, bacteria consume oxygen until there is little or none left in these bottom waters. (chesapeakebay.net)
  • As tissues consume oxygen to produce energy, haemoglobin in the local capillary blood supply is stimulated to release its bound oxygen. (lu.se)
  • Chemical oxygen generators are not used for the cockpit crew, who are typically supplied using compressed oxygen canisters, also known as oxygen bottles. (wikipedia.org)
  • Find content from Oxygen and the NBCUniversal family of networks on NBC.com ! (aol.com)
  • The lunar soil's oxygen content has three components: One is rich in oxygen-16, and that is from the solar wind. (space.com)
  • Exposure times to oxygen at different depths of water (and, hence, different levels of pressure) were quantified and tested based on time to convulsions. (medscape.com)
  • Marine life is in serious trouble if ocean oxygen levels continue to plummet. (inhabitat.com)
  • As dissolved oxygen levels decrease, it becomes harder for animals to get the oxygen they need to survive. (chesapeakebay.net)
  • Worms and clams that live in the Bay's muddy bottom-where oxygen levels are naturally low-need dissolved oxygen concentrations of at least 1 mg/L. (chesapeakebay.net)
  • These levels represent areas in the water column that have varying dissolved oxygen concentrations. (chesapeakebay.net)
  • To see dissolved oxygen levels throughout the Chesapeake Bay, visit Eyes on the Bay (for Maryland waters) or Virginia Estuarine and Coastal Observing System (for Virginia waters). (chesapeakebay.net)
  • Areas in the Bay that have low dissolved oxygen levels are the result of a complex interaction of several natural and man-made factors, including temperature, nutrient pollution , water flows, and the shape of the Bay's bottom. (chesapeakebay.net)
  • The division between water flowing from the ocean and from the Bay's freshwater rivers and streams can also influence dissolved oxygen levels. (chesapeakebay.net)
  • The tool can then create health facility archetypes to aggregate oxygen demand for a full geographical area or at various levels of the health system. (unicef.org)
  • This resulted in a strengthened and sustainable oxygen system at all levels of health care and reduced patient referrals. (unicef.org)
  • Experts say the real figure is actually smaller, and furthermore, this way of thinking is misleading given the true nature of the Amazon's effect on global oxygen levels. (newsweek.com)
  • In fact, the world's oxygen levels are actually quite stable and are not dependent on rain forests, which use up as much of the gas as they produce in the long run, according to Philip Fearnside, a professor at Brazil's National Institute of Amazonian Research. (newsweek.com)
  • So far no one knows exactly why oxygen levels are declining, but there are a few prominent hypotheses. (inhabitat.com)
  • But oxygen levels are still going down - and scientists aren't sure why. (inhabitat.com)
  • It's difficult for scientists to know just which hypothesis is correct, since oxygen levels are connected to other processes such as volcanic activity and even the biodiversity present on Earth. (inhabitat.com)
  • A new scientific study measures oxygen levels over time to show they have declined. (inhabitat.com)
  • They found oxygen levels decreased during the past 800,000 years or so and continue to go down. (inhabitat.com)
  • The importance of the free radical chain oxidation and the singlet oxygen-dependent oxidation is suggested by a decrease in skin levels of alpha-tocopherol, ubiquinol-10, and ascorbic acid with a concomitant formation of lipid hydroperoxides during UV irradiation of murine skin, and the formation of squalene hydroperoxides in human skin upon UV exposure, respectively. (nih.gov)
  • Used in isolation, mechanical aeration is slower to raise oxygen levels, but it is a great option for chronic issues such as regular algal blooms," says Storey. (newscientist.com)
  • The MODEL 1000RS Portable Trace Oxygen Analyzer is the undisputed leader when measuring ppm levels of oxygen in the natural gas industry. (environmental-expert.com)
  • After you complete setup, open the Blood Oxygen app on your Apple Watch to measure your blood oxygen levels. (apple.com)
  • The Blood Oxygen app on your Apple Watch will occasionally measure your blood oxygen levels if background measurements are on. (apple.com)
  • Then we can use today's models to see whether this leaching could affect the oxygen levels on the bed of the Baltic Sea sufficiently to cause oxygen depletion. (lu.se)
  • The research team has discovered a new isotope of Oxygen, known as 28 O. (dur.ac.uk)
  • Japan's Kaguya lunar orbiter detected the oxygen isotope on the moon. (space.com)
  • Terada told Space.com that the evidence for where the ions came from was the isotope oxygen-16. (space.com)
  • For example, this could include where to store the oxygen tanks or install more plug points. (bliss.org.uk)
  • Therefore, the patient cannot benefit from most of the positive effects of HBOT, which are systemic or occur at a level deeper than topical oxygen can penetrate (see Hyperbaric Physics and Physiology section below). (medscape.com)
  • X-ray absorption spectroscopy data suggest that these so-called oxygen "breaths" may control the transfer of volatile elements from the deep Earth to the surface, shaping our planet's evolution. (esrf.fr)
  • The moon may carry material produced by life from Earth dating back to when plants first filled the planet's air with oxygen, according to study of data from a Japanese lunar orbiter. (space.com)
  • Marketers of oxygenated bottled water and oxygen bars are breathing down my neck. (livescience.com)
  • [ 5-10 ] Cardiac output may be calculated by using the Fick equation if Vȯ 2 , hemoglobin level, and the arterial-venous oxygen difference are known. (medscape.com)
  • A person with excellent arterial oxygen supply could have a region of poorly perfused tissue that becomes necrotic. (lu.se)
  • This comes in powder form, and when it's mixed with water, billions of oxygen ions attack dirt and stain molecules, blasting them apart. (tampabay.com)
  • The ultimate "green car", fuel cell vehicles (FCVs) run on electricity made by mixing hydrogen fuel and oxygen in the air - a technology first used in the Apollo moon project in the 1960s. (electrochem.org)
  • Oxygen is the third most abundant element in the universe after hydrogen and helium, and is essential for all forms of life on Earth, as the chemical basis of respiration and a building block of carbohydrates. (sciencedaily.com)
  • The EA pumps oxygen in several ways, such as using liquid hydrogen peroxide, which breaks down into water and oxygen, and mechanical aerators, which increase oxygen in the water body by disturbing its surface. (newscientist.com)
  • With the relevant data from users, the Oxygen System Planning Tool recommends an oxygen source to meet those needs (i.e. a new local oxygen plant, liquid oxygen, concentrators, cylinders from a distant plant, or a mix). (unicef.org)
  • This often involves a combination of cylinders refilled from centralized plants, on-site PSA plants or oxygen concentrators. (unicef.org)
  • This surge of cases is putting intense pressure on the country's healthcare system, which has led to a shortage in supply of oxygen cylinders at medical facilities. (dhl.com)
  • Although India stands as one of the leading oxygen-producers in the world, producing over 7000 tons a day, most of its plants are located far away from the urban hubs, posing a challenge and increase in costs for many healthcare institutes to arrange for their own logistical transportation to replenish their oxygen cylinders. (dhl.com)
  • Oxygen is a fire hazard, so it is important to be very careful around flammable substances and to keep cylinders away from heat sources. (bliss.org.uk)
  • Before the establishment of the oxygen station, obtaining oxygen was a constant struggle, relying on donated cylinders. (who.int)
  • Amid this coverage, many media outlets, charities, celebrities and even world leaders repeated the claim that the Amazon produces 20 percent of the world's oxygen supply. (newsweek.com)
  • There are many, many reasons to be concerned-nay, terrified-by the resurgence of deforestation and burning of Amazonian forests, but a risk to the world's oxygen supply is not one of them. (newsweek.com)
  • It was a surprise to see the claim that 20 percent of the world's oxygen comes from Amazonia surface on mainstream media, Fearnside told Newsweek . (newsweek.com)
  • Historical oxygen depletion in Baltic sediment - a consequence of human impact? (lu.se)
  • The sediment shows that, over the past 2 000 years, there have been periods with and without oxygen depletion. (lu.se)
  • Two thousand years ago, the oxygen conditions on the bed of the Baltic Sea were good, but a few hundred years later, areas of oxygen depletion appeared, visible as black layers in the sediment samples. (lu.se)
  • In the Baltic Sea, the areas of oxygen depletion have increased so much, that it definitely cannot be attributed to a natural phenomenon. (lu.se)
  • In the Baltic Sea, the areas of oxygen depletion have increased so much, that it definitely cannot be attributed to a natural phenomenon", says Johanna Stadmark, project assistant for the Multistressors research environment at Lund University. (lu.se)
  • A chemical oxygen generator is a device that releases oxygen via a chemical reaction . (wikipedia.org)
  • A chlorate candle, or an oxygen candle , is a cylindrical chemical oxygen generator that contains a mix of sodium chlorate and iron powder, which when ignited smolders at about 600 °C (1,112 °F), producing sodium chloride , iron oxide , and at a fixed rate of about 6.5 man-hours of oxygen per kilogram of the mixture. (wikipedia.org)
  • O2PAK® is a portable version of the Safran Aerosystems chemical oxygen generator designed to be activated within seconds of an injury. (safran-group.com)
  • Also, oxygen may be what ultimately kills you, rusting your body from the inside in a process called oxidation and free-radical production. (livescience.com)
  • The released fluid (undulating blue arrows) carries oxygen and its radicals and major chemical elements in their highest oxidation states. (esrf.fr)
  • When a patient is given 100% oxygen under pressure, hemoglobin is saturated, but the blood can be hyperoxygenated by dissolving oxygen within the plasma. (medscape.com)
  • For instance, functional magnetic resonance imaging monitors the blood oxygen level dependent (BOLD) contrast but is sensitive only to deoxygenated hemoglobin and the MRI machine is bulky. (lu.se)
  • Patients in a multiplace chamber breathe 100% oxygen via a mask or close-fitting plastic hood. (medscape.com)
  • When the passengers pulled down on the mask they removed the retaining pins and triggered the production of oxygen. (wikipedia.org)
  • A face mask may be needed to improve oxygen delivery. (denverhealth.org)
  • The Safran Aerosystems MBU-12/P is a pilot oxygen mask suitable for latest-generation aircraft. (safran-group.com)
  • To provide maximum flexibility, Safran Aerosystems has also designed an individual pilot oxygen system that includes an on-demand mask, such as the EROS® mask, and a lightweight composite Kevlar cylinder with our GCD oxygen source. (safran-group.com)
  • While all tissues can withstand a certain degree of oxygen deprivation, without adequate tissue perfusion, cells can die. (hermanmiller.com)
  • If you are out in the cold, for example, the skin perfusion in your wrist might be too low for the sensor to work with the Blood Oxygen app to get a measurement. (apple.com)
  • So if we lost the entire Amazon forest-it would only change atmospheric oxygen-which is thought to weigh 1.2 million gigatons in total-by a small amount, much less than 1 percent. (newsweek.com)
  • A layer of atomic oxygen exists between these two opposing atmospheric currents. (dlr.de)
  • The lowest level represents the Bay's muddy bottom, where species need dissolved oxygen concentrations of at least 1 mg/L. The highest level is farthest up in the water column, where spawning migratory fish and their eggs and larvae need concentrations of up to 6 mg/L. (chesapeakebay.net)
  • The mechanism for the formation of active oxygen species and their reactions with antioxidants is described. (nih.gov)
  • A key point of debate is whether oxygen-containing species, e.g. (nature.com)
  • As ex situ measurements have the potential of exposing the sample to the ambient condition, the origin of the oxygen-containing species on the Cu surface detected by these methods is uncertain. (nature.com)
  • Thanks to upGREAT's outstanding measurement sensitivity and SOFIA's unique capabilities, it was possible to create a map of the oxygen distribution on Venus,' says Heinz-Wilhelm Hübers, Director of the DLR Institute of Optical Sensor Systems and first author of the publication announcing the results . (dlr.de)
  • You can take a blood oxygen measurement at any time with the Blood Oxygen app. (apple.com)
  • Even under ideal conditions, your Apple Watch may not be able to get a reliable blood oxygen measurement every time. (apple.com)
  • For a small percentage of users, various factors may make it impossible to get any blood oxygen measurement. (apple.com)
  • If your heart rate is too high (above 150 bpm) while at rest, you won't be able to get a successful blood oxygen measurement. (apple.com)
  • Background Measurement of oxygen consumption (Vȯ 2 ) is difficult in children but is essential to calculate cardiac index and systemic vascular resistance. (medscape.com)
  • [ 11 ] However, it is difficult to measure Vȯ 2 and cardiac output, and they are rarely measured outside of research investigations, despite the suggestion that measurement of cardiac output and oxygen delivery would improve clinical outcomes of critically ill children. (medscape.com)
  • An oxygen-sensitive colour change sensor used to determine the shelf-life of packaged food could challenge industry food quality and safety practices, says its UK-based inventor. (foodnavigator.com)
  • The development, a sensor which turns blue where excess oxygen is present, indicates when food such as meat may have been compromised and made unsafe for consumption. (foodnavigator.com)
  • Just like humans, all of the Chesapeake Bay's living creatures-from the fish and crabs that swim through its waters to the worms that bury themselves in its muddy bottom- need oxygen to survive. (chesapeakebay.net)
  • Now, if we assume that humans absorb oxygen efficiently through their gut, which they don't, and if the dissolved oxygen in the oxygenated water doesn't bubble into the air when you open the bottle and expose it to standard pressure, which it does, how much O 2 are you getting? (livescience.com)
  • Escaping predators, digestion and other animal activities - including those of humans - require oxygen. (countercurrents.org)
  • Anoxic, or no-oxygen, areas are regions with less than 0.2 mg/L of dissolved oxygen. (chesapeakebay.net)
  • With no dissolved oxygen to sustain animals or plants, ocean anoxic zones are areas where only microbes suited to the environment can live. (countercurrents.org)
  • As such, the demand for life-saving oxygen concentrators in India has gone up in order to cater to the growing need. (dhl.com)
  • 29 January 2024 - With funding received from King Salman Humanitarian Aid and Relief Centre (KSrelief), WHO has set up 5 life-saving oxygen stations in hospitals across 5 key governorates in Yemen. (who.int)
  • Oxygen is too chemically reactive to remain a free element in air without being continuously replenished by the photosynthetic action of living organisms. (wikipedia.org)
  • Tracing the early production of oxygen and other elements requires studying the oldest stars still in existence. (sciencedaily.com)
  • The tool also automatically calculates the distance between known oxygen plants and health facilities to inform when cylinder refilling from a centralized PSA or liquid plant may be the best oxygen source solution. (unicef.org)
  • The tool can also support users to plan the optimum placement of new PSA plants, based on oxygen needs and distance to other health facilities that could benefit from cylinder refilling. (unicef.org)
  • Pressurized oxygen, such as, an oxygen gas cylinder, can react violently in the presence of oil or other lubricants. (lu.se)
  • Qualified for all military aircraft, the MA-1 portable oxygen cylinder with integrated regulator designed by Safran Aerosystems is a self-contained breathing device that provides oxygen to the pilot and that is compatible with standard masks, such as the 358, MBU or fire-fighting and anti-smoke masks. (safran-group.com)
  • Oxygen pumping is an important emergency measure in fish rescue, but keeping rivers cool, protecting flows and reducing pollution are all important longer-term measures to protect rivers against the impacts of climate change," says Steve Ormerod at Cardiff University, UK. (newscientist.com)
  • This tool can be used to support high-level healthcare budgeting and planning needs related to oxygen, including health and procurement specialists and oxygen technology stakeholders. (unicef.org)
  • The OSPT provides procurement lists for each health facility, covering oxygen source equipment, consumables, and diagnostic devices. (unicef.org)
  • This device can deliver oxygen in a traditional, continuous manner, but it also contains a comfort mode in which a dose of oxygen is only administered upon inhalation. (who.int)
  • Rivers can become deoxygenated for a variety of reasons, including sewage dumping that encourages the growth of bacteria, plants and algae, which can result in the consumption of oxygen. (newscientist.com)
  • The general consensus is that optimizing the balance between oxygen consumption (Vȯ 2 ) and delivery is important in managing critically ill patients. (medscape.com)
  • Optimizing oxygen consumption and delivery is important in critically ill children. (medscape.com)
  • Thus, the percentage of oxy-haemoglobin in a volume of tissue (StO2) is an indicator of tissue oxygen consumption and, ultimately, tissue health. (lu.se)
  • Hot weather can also play a role, as water holds less oxygen at higher temperatures. (newscientist.com)
  • a warmer climate leads to greater productivity in the sea and thus the use of more oxygen from the sediment, while there is less oxygen dissolved in the water. (lu.se)
  • The new system aims to provide oxygen for long-duration space flights. (electrochem.org)
  • Now, with the station in operation, we are not only self-sufficient but can also provide oxygen to others. (who.int)
  • The chemical reaction is exothermic and the exterior temperature of the canister will reach 260 °C (500 °F). It will produce oxygen for 12 to 22 minutes. (wikipedia.org)
  • Commercial aircraft provide emergency oxygen to passengers to protect them in case of loss of cabin pressure. (wikipedia.org)
  • English rivers were pumped with emergency oxygen in a last-ditch effort to save fish from dying on almost 100 occasions in the past five years, New Scientist can reveal. (newscientist.com)
  • Graeme Storey , fisheries manager at the EA, says the organisation hasn't officially analysed whether the use of emergency oxygen measures has increased in recent years, but says that anecdotally it seems like it has. (newscientist.com)
  • Climate change is likely to increase the need for emergency oxygen in rivers in the future, says Storey. (newscientist.com)
  • Most of the mass of living organisms is oxygen as a component of water, the major constituent of lifeforms. (wikipedia.org)
  • Did microbes once thrive in arsenic world - a world without oxygen? (uncommondescent.com)
  • Scientists using beamline BM30 have exploited arsenic as an oxygen probe in rocks of the former subduction zone of Himalaya, to reveal O2 release at depths of 100 km during subduction. (esrf.fr)
  • Future Mars colonists are going to need oxygen, and NASA has a plan to make it. (inhabitat.com)
  • Andrei Lapenas, a professor of climatology from the University at Albany, SUNY, speaking to Newsweek, put a figure on the Amazon's oxygen production, estimating that the forest consumes and emits about 32 gigatons of oxygen per year. (newsweek.com)
  • We were supplied with devices like the pulse oximeters, oxygen concentrators. (unicef.org)
  • It is measured in milligrams per liter (mg/L), the number of milligrams of oxygen dissolved in a liter of water. (chesapeakebay.net)
  • But worms, fish, crabs, and other underwater animals use gills to get oxygen from the water. (chesapeakebay.net)
  • As water moves across an animal's gills, oxygen is removed and passed into the blood. (chesapeakebay.net)
  • Gills work better when there is more oxygen in the surrounding water. (chesapeakebay.net)
  • How does oxygen get into the water? (chesapeakebay.net)
  • Not only does oxygen bleach do this on wood decks, it works on anything that's water washable. (tampabay.com)
  • I decided to use the oxygen bleach powder in the mop water. (tampabay.com)
  • Aside from the O part in H 2 O, ordinary water has about 0.5 percent dissolved oxygen gas. (livescience.com)
  • Oxygenated water can carry as much as 5 percent oxygen. (livescience.com)
  • Although air is about 20 percent oxygen and the oxygenated water is 5 percent dissolved oxygen, the density is different, so this isn't quite 4:1. (livescience.com)
  • Photosystem II is a protein complex in plants, algae and cyanobacteria that is responsible for splitting water and producing the oxygen we breathe. (sciencedaily.com)
  • The oxygen-evolving complex is surrounded by water and protein. (sciencedaily.com)
  • This research focused on the transition from S2 to S3, the last stable intermediate state before an oxygen molecule is produced. (sciencedaily.com)
  • Of course, one outcome of a shorter period during which oxygen is stable enough for complex life is - the obvious one - that all that bewildering complexity of life had to just sort of fall into place in a shorter period of time. (uncommondescent.com)