Carbon Radioisotopes: Unstable isotopes of carbon that decay or disintegrate emitting radiation. C atoms with atomic weights 10, 11, and 14-16 are radioactive carbon isotopes.Carbon: A nonmetallic element with atomic symbol C, atomic number 6, and atomic weight [12.0096; 12.0116]. It may occur as several different allotropes including DIAMOND; CHARCOAL; and GRAPHITE; and as SOOT from incompletely burned fuel.Radioisotopes: Isotopes that exhibit radioactivity and undergo radioactive decay. (From Grant & Hackh's Chemical Dictionary, 5th ed & McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Zinc Radioisotopes: Unstable isotopes of zinc that decay or disintegrate emitting radiation. Zn atoms with atomic weights 60-63, 65, 69, 71, and 72 are radioactive zinc isotopes.Radioisotope Dilution Technique: Method for assessing flow through a system by injection of a known quantity of radionuclide into the system and monitoring its concentration over time at a specific point in the system. (From Dorland, 28th ed)Strontium Radioisotopes: Unstable isotopes of strontium that decay or disintegrate spontaneously emitting radiation. Sr 80-83, 85, and 89-95 are radioactive strontium isotopes.Carbon Dioxide: A colorless, odorless gas that can be formed by the body and is necessary for the respiration cycle of plants and animals.Iodine Radioisotopes: Unstable isotopes of iodine that decay or disintegrate emitting radiation. I atoms with atomic weights 117-139, except I 127, are radioactive iodine isotopes.Krypton Radioisotopes: Unstable isotopes of krypton that decay or disintegrate emitting radiation. Kr atoms with atomic weights 74-77, 79, 81, 85, and 87-94 are radioactive krypton isotopes.Carbon Monoxide: 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)Nanotubes, Carbon: Nanometer-sized tubes composed mainly of CARBON. Such nanotubes are used as probes for high-resolution structural and chemical imaging of biomolecules with ATOMIC FORCE MICROSCOPY.Indium Radioisotopes: Unstable isotopes of indium that decay or disintegrate emitting radiation. In atoms with atomic weights 106-112, 113m, 114, and 116-124 are radioactive indium isotopes.Sodium Radioisotopes: Unstable isotopes of sodium that decay or disintegrate emitting radiation. Na atoms with atomic weights 20-22 and 24-26 are radioactive sodium isotopes.Radioactivity: The spontaneous transformation of a nuclide into one or more different nuclides, accompanied by either the emission of particles from the nucleus, nuclear capture or ejection of orbital electrons, or fission. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Barium Radioisotopes: Unstable isotopes of barium that decay or disintegrate emitting radiation. Ba atoms with atomic weights 126-129, 131, 133, and 139-143 are radioactive barium isotopes.Radionuclide Imaging: The production of an image obtained by cameras that detect the radioactive emissions of an injected radionuclide as it has distributed differentially throughout tissues in the body. The image obtained from a moving detector is called a scan, while the image obtained from a stationary camera device is called a scintiphotograph.Yttrium Radioisotopes: Unstable isotopes of yttrium that decay or disintegrate emitting radiation. Y atoms with atomic weights 82-88 and 90-96 are radioactive yttrium isotopes.Tin Radioisotopes: Unstable isotopes of tin that decay or disintegrate emitting radiation. Sn atoms with atomic weights 108-111, 113, 120-121, 123 and 125-128 are tin radioisotopes.Carbon Isotopes: Stable carbon atoms that have the same atomic number as the element carbon, but differ in atomic weight. C-13 is a stable carbon isotope.Iron Radioisotopes: Unstable isotopes of iron that decay or disintegrate emitting radiation. Fe atoms with atomic weights 52, 53, 55, and 59-61 are radioactive iron isotopes.Copper Radioisotopes: Unstable isotopes of copper that decay or disintegrate emitting radiation. Cu atoms with atomic weights 58-62, 64, and 66-68 are radioactive copper isotopes.Phosphorus Radioisotopes: Unstable isotopes of phosphorus that decay or disintegrate emitting radiation. P atoms with atomic weights 28-34 except 31 are radioactive phosphorus isotopes.Beta Particles: High energy POSITRONS or ELECTRONS ejected from a disintegrating atomic nucleus.Technetium: The first artificially produced element and a radioactive fission product of URANIUM. Technetium has the atomic symbol Tc, atomic number 43, and atomic weight 98.91. All technetium isotopes are radioactive. Technetium 99m (m=metastable) which is the decay product of Molybdenum 99, has a half-life of about 6 hours and is used diagnostically as a radioactive imaging agent. Technetium 99 which is a decay product of technetium 99m, has a half-life of 210,000 years.Carbon Monoxide Poisoning: Toxic asphyxiation due to the displacement of oxygen from oxyhemoglobin by carbon monoxide.Mercury Radioisotopes: Unstable isotopes of mercury that decay or disintegrate emitting radiation. Hg atoms with atomic weights 185-195, 197, 203, 205, and 206 are radioactive mercury isotopes.Technetium Tc 99m Sulfur Colloid: A gamma-emitting radionuclide imaging agent used for the diagnosis of diseases in many tissues, particularly in the gastrointestinal system, liver, and spleen.Cesium Isotopes: Stable cesium atoms that have the same atomic number as the element cesium, but differ in atomic weight. Cs-133 is a naturally occurring isotope.Cerium Radioisotopes: Unstable isotopes of cerium that decay or disintegrate emitting radiation. Ce atoms with atomic weights 132-135, 137, 139, and 141-148 are radioactive cerium isotopes.Cobalt Isotopes: Stable cobalt atoms that have the same atomic number as the element cobalt, but differ in atomic weight. Co-59 is a stable cobalt isotope.Isotope Labeling: Techniques for labeling a substance with a stable or radioactive isotope. It is not used for articles involving labeled substances unless the methods of labeling are substantively discussed. Tracers that may be labeled include chemical substances, cells, or microorganisms.Hafnium: Hafnium. A metal element of atomic number 72 and atomic weight 178.49, symbol Hf. (From Dorland, 28th ed)Gold Radioisotopes: Unstable isotopes of gold that decay or disintegrate emitting radiation. Au 185-196, 198-201, and 203 are radioactive gold isotopes.Lead Radioisotopes: Unstable isotopes of lead that decay or disintegrate emitting radiation. Pb atoms with atomic weights 194-203, 205, and 209-214 are radioactive lead isotopes.Diagnostic Techniques, Radioisotope: Any diagnostic evaluation using radioactive (unstable) isotopes. This diagnosis includes many nuclear medicine procedures as well as radioimmunoassay tests.Zinc Isotopes: Stable zinc atoms that have the same atomic number as the element zinc, but differ in atomic weight. Zn-66-68, and 70 are stable zinc isotopes.Sulfur Radioisotopes: Unstable isotopes of sulfur that decay or disintegrate spontaneously emitting radiation. S 29-31, 35, 37, and 38 are radioactive sulfur isotopes.Cadmium Radioisotopes: Unstable isotopes of cadmium that decay or disintegrate emitting radiation. Cd atoms with atomic weights 103-105, 107, 109, 115, and 117-119 are radioactive cadmium isotopes.Astatine: Astatine. A radioactive halogen with the atomic symbol At, atomic number 85, and atomic weight 210. Its isotopes range in mass number from 200 to 219 and all have an extremely short half-life. Astatine may be of use in the treatment of hyperthyroidism.Radioimmunotherapy: Radiotherapy where cytotoxic radionuclides are linked to antibodies in order to deliver toxins directly to tumor targets. Therapy with targeted radiation rather than antibody-targeted toxins (IMMUNOTOXINS) has the advantage that adjacent tumor cells, which lack the appropriate antigenic determinants, can be destroyed by radiation cross-fire. Radioimmunotherapy is sometimes called targeted radiotherapy, but this latter term can also refer to radionuclides linked to non-immune molecules (see RADIOTHERAPY).Lutetium: Lutetium. An element of the rare earth family of metals. It has the atomic symbol Lu, atomic number 71, and atomic weight 175.Rhenium: Rhenium. A metal, atomic number 75, atomic weight 186.2, symbol Re. (Dorland, 28th ed)Samarium: Samarium. An element of the rare earth family of metals. It has the atomic symbol Sm, atomic number 62, and atomic weight 150.36. The oxide is used in the control rods of some nuclear reactors.Radiopharmaceuticals: Compounds that are used in medicine as sources of radiation for radiotherapy and for diagnostic purposes. They have numerous uses in research and industry. (Martindale, The Extra Pharmacopoeia, 30th ed, p1161)Soil Pollutants, Radioactive: Pollutants, present in soil, which exhibit radioactivity.Carbon Tetrachloride: A solvent for oils, fats, lacquers, varnishes, rubber waxes, and resins, and a starting material in the manufacturing of organic compounds. Poisoning by inhalation, ingestion or skin absorption is possible and may be fatal. (Merck Index, 11th ed)Bromine Radioisotopes: Unstable isotopes of bromine that decay or disintegrate emitting radiation. Br atoms with atomic weights 74-78, 80, and 82-90 are radioactive bromine isotopes.Scintillation Counting: Detection and counting of scintillations produced in a fluorescent material by ionizing radiation.Subdural Effusion: Leakage and accumulation of CEREBROSPINAL FLUID in the subdural space which may be associated with an infectious process; CRANIOCEREBRAL TRAUMA; BRAIN NEOPLASMS; INTRACRANIAL HYPOTENSION; and other conditions.Calcium Isotopes: Stable calcium atoms that have the same atomic number as the element calcium, but differ in atomic weight. Ca-42-44, 46, and 48 are stable calcium isotopes.Radioactive Waste: Liquid, solid, or gaseous waste resulting from mining of radioactive ore, production of reactor fuel materials, reactor operation, processing of irradiated reactor fuels, and related operations, and from use of radioactive materials in research, industry, and medicine. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Carbon Sequestration: Any of several processes for the permanent or long-term artificial or natural capture or removal and storage of carbon dioxide and other forms of carbon, through biological, chemical or physical processes, in a manner that prevents it from being released into the atmosphere.Radiometric Dating: Techniques used to determine the age of materials, based on the content and half-lives of the RADIOACTIVE ISOTOPES they contain.Serum Albumin, Radio-Iodinated: Normal human serum albumin mildly iodinated with radioactive iodine (131-I) which has a half-life of 8 days, and emits beta and gamma rays. It is used as a diagnostic aid in blood volume determination. (from Merck Index, 11th ed)Ruthenium Radioisotopes: Unstable isotopes of ruthenium that decay or disintegrate emitting radiation. Ru atoms with atomic weights 93-95, 97, 103, and 105-108 are radioactive ruthenium isotopes.Carbon Disulfide: A colorless, flammable, poisonous liquid, CS2. It is used as a solvent, and is a counterirritant and has local anesthetic properties but is not used as such. It is highly toxic with pronounced CNS, hematologic, and dermatologic effects.Selenium Radioisotopes: Unstable isotopes of selenium that decay or disintegrate emitting radiation. Se atoms with atomic weights 70-73, 75, 79, 81, and 83-85 are radioactive selenium isotopes.Isotopes: Atomic species differing in mass number but having the same atomic number. (Grant & Hackh's Chemical Dictionary, 5th ed)Alpha Particles: Positively charged particles composed of two protons and two NEUTRONS, i.e. equivalent to HELIUM nuclei, which are emitted during disintegration of heavy ISOTOPES. Alpha rays have very strong ionizing power, but weak penetrability.Tungsten: Tungsten. A metallic element with the atomic symbol W, atomic number 74, and atomic weight 183.85. It is used in many manufacturing applications, including increasing the hardness, toughness, and tensile strength of steel; manufacture of filaments for incandescent light bulbs; and in contact points for automotive and electrical apparatus.Heterocyclic Compounds, 1-Ring: A class of organic compounds containing a ring structure made up of more than one kind of atom, usually carbon plus another atom. The ring structure can be aromatic or nonaromatic.Sodium Pertechnetate Tc 99m: A gamma-emitting radionuclide imaging agent used for the diagnosis of diseases in many tissues, particularly in the gastrointestinal system, cardiovascular and cerebral circulation, brain, thyroid, and joints.Spectrometry, Gamma: Determination of the energy distribution of gamma rays emitted by nuclei. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Tissue Distribution: Accumulation of a drug or chemical substance in various organs (including those not relevant to its pharmacologic or therapeutic action). This distribution depends on the blood flow or perfusion rate of the organ, the ability of the drug to penetrate organ membranes, tissue specificity, protein binding. The distribution is usually expressed as tissue to plasma ratios.Radioisotope Teletherapy: A type of high-energy radiotherapy using a beam of gamma-radiation produced by a radioisotope source encapsulated within a teletherapy unit.Pentetic Acid: An iron chelating agent with properties like EDETIC ACID. DTPA has also been used as a chelator for other metals, such as plutonium.Methods: A series of steps taken in order to conduct research.Nuclear Medicine: A specialty field of radiology concerned with diagnostic, therapeutic, and investigative use of radioactive compounds in a pharmaceutical form.Technetium Tc 99m Pentetate: A technetium imaging agent used in renal scintigraphy, computed tomography, lung ventilation imaging, gastrointestinal scintigraphy, and many other procedures which employ radionuclide imaging agents.TritiumRadiometry: The measurement of radiation by photography, as in x-ray film and film badge, by Geiger-Mueller tube, and by SCINTILLATION COUNTING.Rosaniline Dyes: Compounds that contain the triphenylmethane aniline structure found in rosaniline. Many of them have a characteristic magenta color and are used as COLORING AGENTS.Nostoc commune: A form species of spore-producing CYANOBACTERIA, in the family Nostocaceae, order Nostocales. It is an important source of fixed NITROGEN in nutrient-depleted soils. When wet, it appears as a jelly-like mass.Carbon Tetrachloride PoisoningWhole-Body Counting: Measurement of radioactivity in the entire human body.Potassium Radioisotopes: Unstable isotopes of potassium that decay or disintegrate emitting radiation. K atoms with atomic weights 37, 38, 40, and 42-45 are radioactive potassium isotopes.Iodohippuric Acid: An iodine-containing compound used in pyelography as a radiopaque medium. If labeled with radioiodine, it can be used for studies of renal function.Organometallic Compounds: A class of compounds of the type R-M, where a C atom is joined directly to any other element except H, C, N, O, F, Cl, Br, I, or At. (Grant & Hackh's Chemical Dictionary, 5th ed)Radiation Dosage: The amount of radiation energy that is deposited in a unit mass of material, such as tissues of plants or animal. In RADIOTHERAPY, radiation dosage is expressed in gray units (Gy). In RADIOLOGIC HEALTH, the dosage is expressed by the product of absorbed dose (Gy) and quality factor (a function of linear energy transfer), and is called radiation dose equivalent in sievert units (Sv).Intestinal Absorption: Uptake of substances through the lining of the INTESTINES.Positron-Emission Tomography: An imaging technique using compounds labelled with short-lived positron-emitting radionuclides (such as carbon-11, nitrogen-13, oxygen-15 and fluorine-18) to measure cell metabolism. It has been useful in study of soft tissues such as CANCER; CARDIOVASCULAR SYSTEM; and brain. SINGLE-PHOTON EMISSION-COMPUTED TOMOGRAPHY is closely related to positron emission tomography, but uses isotopes with longer half-lives and resolution is lower.Vitamin B 12: A cobalt-containing coordination compound produced by intestinal micro-organisms and found also in soil and water. Higher plants do not concentrate vitamin B 12 from the soil and so are a poor source of the substance as compared with animal tissues. INTRINSIC FACTOR is important for the assimilation of vitamin B 12.Carbon Footprint: A measure of the total greenhouse gas emissions produced by an individual, organization, event, or product. It is measured in units of equivalent kilograms of CARBON DIOXIDE generated in a given time frame.Absorption: The physical or physiological processes by which substances, tissue, cells, etc. take up or take in other substances or energy.Kinetics: The rate dynamics in chemical or physical systems.Sentinel Lymph Node Biopsy: A diagnostic procedure used to determine whether LYMPHATIC METASTASIS has occurred. The sentinel lymph node is the first lymph node to receive drainage from a neoplasm.Technetium Tc 99m Medronate: A gamma-emitting radionuclide imaging agent used primarily in skeletal scintigraphy. Because of its absorption by a variety of tumors, it is useful for the detection of neoplasms.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Bismuth: A metallic element that has the atomic symbol Bi, atomic number 83 and atomic weight 208.98.Avidin: A specific protein in egg albumin that interacts with BIOTIN to render it unavailable to mammals, thereby producing biotin deficiency.Antibodies, Monoclonal: Antibodies produced by a single clone of cells.Autoradiography: The making of a radiograph of an object or tissue by recording on a photographic plate the radiation emitted by radioactive material within the object. (Dorland, 27th ed)Phosphorus Isotopes: Stable phosphorus atoms that have the same atomic number as the element phosphorus, but differ in atomic weight. P-31 is a stable phosphorus isotope.Glucose: 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.Cesium Radioisotopes: Unstable isotopes of cesium that decay or disintegrate emitting radiation. Cs atoms with atomic weights of 123, 125-132, and 134-145 are radioactive cesium isotopes.Brachytherapy: A collective term for interstitial, intracavity, and surface radiotherapy. It uses small sealed or partly-sealed sources that may be placed on or near the body surface or within a natural body cavity or implanted directly into the tissues.Iridium Radioisotopes: Unstable isotopes of iridium that decay or disintegrate emitting radiation. Ir atoms with atomic weights 182-190, 192, and 194-198 are radioactive iridium isotopes.Mass Spectrometry: An analytical method used in determining the identity of a chemical based on its mass using mass analyzers/mass spectrometers.Nitrogen: 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.Evaluation Studies as Topic: Studies determining the effectiveness or value of processes, personnel, and equipment, or the material on conducting such studies. For drugs and devices, CLINICAL TRIALS AS TOPIC; DRUG EVALUATION; and DRUG EVALUATION, PRECLINICAL are available.Biomass: Total mass of all the organisms of a given type and/or in a given area. (From Concise Dictionary of Biology, 1990) It includes the yield of vegetative mass produced from any given crop.Liver: A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.Soot: A dark powdery deposit of unburned fuel residues, composed mainly of amorphous CARBON and some HYDROCARBONS, that accumulates in chimneys, automobile mufflers and other surfaces exposed to smoke. It is the product of incomplete combustion of carbon-rich organic fuels in low oxygen conditions. It is sometimes called lampblack or carbon black and is used in INK, in rubber tires, and to prepare CARBON NANOTUBES.CarboxyhemoglobinHalf-Life: The time it takes for a substance (drug, radioactive nuclide, or other) to lose half of its pharmacologic, physiologic, or radiologic activity.Octreotide: A potent, long-acting synthetic SOMATOSTATIN octapeptide analog that inhibits secretion of GROWTH HORMONE and is used to treat hormone-secreting tumors; DIABETES MELLITUS; HYPOTENSION, ORTHOSTATIC; HYPERINSULINISM; hypergastrinemia; and small bowel fistula.Atmosphere: The gaseous envelope surrounding a planet or similar body. (From Random House Unabridged Dictionary, 2d ed)Sensitivity and Specificity: Binary classification measures to assess test results. Sensitivity or recall rate is the proportion of true positives. Specificity is the probability of correctly determining the absence of a condition. (From Last, Dictionary of Epidemiology, 2d ed)Tomography, Emission-Computed: Tomography using radioactive emissions from injected RADIONUCLIDES and computer ALGORITHMS to reconstruct an image.Molecular Sequence Data: 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.Cobalt Radioisotopes: Unstable isotopes of cobalt that decay or disintegrate emitting radiation. Co atoms with atomic weights of 54-64, except 59, are radioactive cobalt isotopes.Zinc: A metallic element of atomic number 30 and atomic weight 65.38. It is a necessary trace element in the diet, forming an essential part of many enzymes, and playing an important role in protein synthesis and in cell division. Zinc deficiency is associated with ANEMIA, short stature, HYPOGONADISM, impaired WOUND HEALING, and geophagia. It is known by the symbol Zn.Iron: 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.Biological Transport: The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.Receptors, Somatostatin: Cell surface proteins that bind somatostatin and trigger intracellular changes which influence the behavior of cells. Somatostatin is a hypothalamic hormone, a pancreatic hormone, and a central and peripheral neurotransmitter. Activated somatostatin receptors on pituitary cells inhibit the release of growth hormone; those on endocrine and gastrointestinal cells regulate the absorption and utilization of nutrients; and those on neurons mediate somatostatin's role as a neurotransmitter.Biodegradation, Environmental: Elimination of ENVIRONMENTAL POLLUTANTS; PESTICIDES and other waste using living organisms, usually involving intervention of environmental or sanitation engineers.Bone Neoplasms: Tumors or cancer located in bone tissue or specific BONES.Radiotherapy Dosage: The total amount of radiation absorbed by tissues as a result of radiotherapy.Metabolic Clearance Rate: Volume of biological fluid completely cleared of drug metabolites as measured in unit time. Elimination occurs as a result of metabolic processes in the kidney, liver, saliva, sweat, intestine, heart, brain, or other site.Soil: The unconsolidated mineral or organic matter on the surface of the earth that serves as a natural medium for the growth of land plants.Chromatography, High Pressure Liquid: Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.Biological Assay: A method of measuring the effects of a biologically active substance using an intermediate in vivo or in vitro tissue or cell model under controlled conditions. It includes virulence studies in animal fetuses in utero, mouse convulsion bioassay of insulin, quantitation of tumor-initiator systems in mouse skin, calculation of potentiating effects of a hormonal factor in an isolated strip of contracting stomach muscle, etc.Culture Media: Any liquid or solid preparation made specifically for the growth, storage, or transport of microorganisms or other types of cells. The variety of media that exist allow for the culturing of specific microorganisms and cell types, such as differential media, selective media, test media, and defined media. Solid media consist of liquid media that have been solidified with an agent such as AGAR or GELATIN.Mice, Nude: Mutant mice homozygous for the recessive gene "nude" which fail to develop a thymus. They are useful in tumor studies and studies on immune responses.Transplantation, Heterologous: Transplantation between animals of different species.Lung: Either of the pair of organs occupying the cavity of the thorax that effect the aeration of the blood.Erythrocytes: Red blood cells. Mature erythrocytes are non-nucleated, biconcave disks containing HEMOGLOBIN whose function is to transport OXYGEN.Acetates: Derivatives of ACETIC ACID. Included under this heading are a broad variety of acid forms, salts, esters, and amides that contain the carboxymethane structure.Feces: Excrement from the INTESTINES, containing unabsorbed solids, waste products, secretions, and BACTERIA of the DIGESTIVE SYSTEM.Tomography, Emission-Computed, Single-Photon: A method of computed tomography that uses radionuclides which emit a single photon of a given energy. The camera is rotated 180 or 360 degrees around the patient to capture images at multiple positions along the arc. The computer is then used to reconstruct the transaxial, sagittal, and coronal images from the 3-dimensional distribution of radionuclides in the organ. The advantages of SPECT are that it can be used to observe biochemical and physiological processes as well as size and volume of the organ. The disadvantage is that, unlike positron-emission tomography where the positron-electron annihilation results in the emission of 2 photons at 180 degrees from each other, SPECT requires physical collimation to line up the photons, which results in the loss of many available photons and hence degrades the image.Graphite: An allotropic form of carbon that is used in pencils, as a lubricant, and in matches and explosives. It is obtained by mining and its dust can cause lung irritation.Carbon Compounds, Inorganic: Inorganic compounds that contain carbon as an integral part of the molecule but are not derived from hydrocarbons.Photosynthesis: 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)Carbohydrate Metabolism: Cellular processes in biosynthesis (anabolism) and degradation (catabolism) of CARBOHYDRATES.Oxygen: 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.Nitrogen Radioisotopes: Unstable isotopes of nitrogen that decay or disintegrate emitting radiation. N atoms with atomic weights 12, 13, 16, 17, and 18 are radioactive nitrogen isotopes.Biopsy, Needle: Removal and examination of tissue obtained through a transdermal needle inserted into the specific region, organ, or tissue being analyzed.Rabbits: The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.Trees: Woody, usually tall, perennial higher plants (Angiosperms, Gymnosperms, and some Pterophyta) having usually a main stem and numerous branches.Electrodes: Electric conductors through which electric currents enter or leave a medium, whether it be an electrolytic solution, solid, molten mass, gas, or vacuum.Fluorescent Dyes: Agents that emit light after excitation by light. The wave length of the emitted light is usually longer than that of the incident light. Fluorochromes are substances that cause fluorescence in other substances, i.e., dyes used to mark or label other compounds with fluorescent tags.Chromium Radioisotopes: Unstable isotopes of chromium that decay or disintegrate emitting radiation. Cr atoms with atomic weights of 46-49, 51, 55, and 56 are radioactive chromium isotopes.Kidney: Body organ that filters blood for the secretion of URINE and that regulates ion concentrations.Feasibility Studies: Studies to determine the advantages or disadvantages, practicability, or capability of accomplishing a projected plan, study, or project.Bone and Bones: A specialized CONNECTIVE TISSUE that is the main constituent of the SKELETON. The principle cellular component of bone is comprised of OSTEOBLASTS; OSTEOCYTES; and OSTEOCLASTS, while FIBRILLAR COLLAGENS and hydroxyapatite crystals form the BONE MATRIX.Oxidation-Reduction: 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).Reproducibility of Results: The statistical reproducibility of measurements (often in a clinical context), including the testing of instrumentation or techniques to obtain reproducible results. The concept includes reproducibility of physiological measurements, which may be used to develop rules to assess probability or prognosis, or response to a stimulus; reproducibility of occurrence of a condition; and reproducibility of experimental results.Methane: The simplest saturated hydrocarbon. It is a colorless, flammable gas, slightly soluble in water. It is one of the chief constituents of natural gas and is formed in the decomposition of organic matter. (Grant & Hackh's Chemical Dictionary, 5th ed)Autotrophic Processes: The processes by which organisms use simple inorganic substances such as gaseous or dissolved carbon dioxide and inorganic nitrogen as nutrient sources. Contrasts with heterotrophic processes which make use of organic materials as the nutrient supply source. Autotrophs can be either chemoautotrophs (or chemolithotrophs), largely ARCHAEA and BACTERIA, which also use simple inorganic substances for their metabolic energy reguirements; or photoautotrophs (or photolithotrophs), such as PLANTS and CYANOBACTERIA, which derive their energy from light. Depending on environmental conditions some organisms can switch between different nutritional modes (autotrophy; HETEROTROPHY; chemotrophy; or PHOTOTROPHY) to utilize different sources to meet their nutrient and energy requirements.Ecosystem: A functional system which includes the organisms of a natural community together with their environment. (McGraw Hill Dictionary of Scientific and Technical Terms, 4th ed)Calcium Radioisotopes: Unstable isotopes of calcium that decay or disintegrate emitting radiation. Ca atoms with atomic weights 39, 41, 45, 47, 49, and 50 are radioactive calcium isotopes.Xenon Radioisotopes: Unstable isotopes of xenon that decay or disintegrate emitting radiation. Xe atoms with atomic weights 121-123, 125, 127, 133, 135, 137-145 are radioactive xenon isotopes.Radioisotope Renography: Graphic tracing over a time period of radioactivity measured externally over the kidneys following intravenous injection of a radionuclide which is taken up and excreted by the kidneys.Rubidium Radioisotopes: Unstable isotopes of rubidium that decay or disintegrate emitting radiation. Rb atoms with atomic weights 79-84, and 86-95 are radioactive rubidium isotopes.Sodium: A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.Swine: Any of various animals that constitute the family Suidae and comprise stout-bodied, short-legged omnivorous mammals with thick skin, usually covered with coarse bristles, a rather long mobile snout, and small tail. Included are the genera Babyrousa, Phacochoerus (wart hogs), and Sus, the latter containing the domestic pig (see SUS SCROFA).Nucleic Acid Hybridization: Widely used technique which exploits the ability of complementary sequences in single-stranded DNAs or RNAs to pair with each other to form a double helix. Hybridization can take place between two complimentary DNA sequences, between a single-stranded DNA and a complementary RNA, or between two RNA sequences. The technique is used to detect and isolate specific sequences, measure homology, or define other characteristics of one or both strands. (Kendrew, Encyclopedia of Molecular Biology, 1994, p503)Heme Oxygenase (Decyclizing): A mixed function oxidase enzyme which during hemoglobin catabolism catalyzes the degradation of heme to ferrous iron, carbon monoxide and biliverdin in the presence of molecular oxygen and reduced NADPH. The enzyme is induced by metals, particularly cobalt. EC 1.14.99.3.Neoplasms: New abnormal growth of tissue. Malignant neoplasms show a greater degree of anaplasia and have the properties of invasion and metastasis, compared to benign neoplasms.Alkanes: The generic name for the group of aliphatic hydrocarbons Cn-H2n+2. They are denoted by the suffix -ane. (Grant & Hackh's Chemical Dictionary, 5th ed)DNA: A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).Magnetic Resonance Spectroscopy: Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING).Hydrogen-Ion Concentration: 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)Seawater: The salinated water of OCEANS AND SEAS that provides habitat for marine organisms.Temperature: 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.Gallium Radioisotopes: Unstable isotopes of gallium that decay or disintegrate emitting radiation. Ga atoms with atomic weights 63-68, 70 and 72-76 are radioactive gallium isotopes.Soil Microbiology: The presence of bacteria, viruses, and fungi in the soil. This term is not restricted to pathogenic organisms.Citric Acid Cycle: A series of oxidative reactions in the breakdown of acetyl units derived from GLUCOSE; FATTY ACIDS; or AMINO ACIDS by means of tricarboxylic acid intermediates. The end products are CARBON DIOXIDE, water, and energy in the form of phosphate bonds.Partial Pressure: 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)Tomography, X-Ray Computed: Tomography using x-ray transmission and a computer algorithm to reconstruct the image.Pseudomonas: A genus of gram-negative, aerobic, rod-shaped bacteria widely distributed in nature. Some species are pathogenic for humans, animals, and plants.Anaerobiosis: 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)Geologic Sediments: A mass of organic or inorganic solid fragmented material, or the solid fragment itself, that comes from the weathering of rock and is carried by, suspended in, or dropped by air, water, or ice. It refers also to a mass that is accumulated by any other natural agent and that forms in layers on the earth's surface, such as sand, gravel, silt, mud, fill, or loess. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed, p1689)Greenhouse Effect: The effect of GLOBAL WARMING and the resulting increase in world temperatures. The predicted health effects of such long-term climatic change include increased incidence of respiratory, water-borne, and vector-borne diseases.Magnetic Resonance Imaging: Non-invasive method of demonstrating internal anatomy based on the principle that atomic nuclei in a strong magnetic field absorb pulses of radiofrequency energy and emit them as radiowaves which can be reconstructed into computerized images. The concept includes proton spin tomographic techniques.Calcium: A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.Bacteria: One of the three domains of life (the others being Eukarya and ARCHAEA), also called Eubacteria. They are unicellular prokaryotic microorganisms which generally possess rigid cell walls, multiply by cell division, and exhibit three principal forms: round or coccal, rodlike or bacillary, and spiral or spirochetal. Bacteria can be classified by their response to OXYGEN: aerobic, anaerobic, or facultatively anaerobic; by the mode by which they obtain their energy: chemotrophy (via chemical reaction) or PHOTOTROPHY (via light reaction); for chemotrophs by their source of chemical energy: CHEMOLITHOTROPHY (from inorganic compounds) or chemoorganotrophy (from organic compounds); and by their source for CARBON; NITROGEN; etc.; HETEROTROPHY (from organic sources) or AUTOTROPHY (from CARBON DIOXIDE). They can also be classified by whether or not they stain (based on the structure of their CELL WALLS) with CRYSTAL VIOLET dye: gram-negative or gram-positive.Rats, Sprague-Dawley: 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.Oxygen Radioisotopes: 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.Fermentation: Anaerobic degradation of GLUCOSE or other organic nutrients to gain energy in the form of ATP. End products vary depending on organisms, substrates, and enzymatic pathways. Common fermentation products include ETHANOL and LACTIC ACID.Electrochemistry: The study of chemical changes resulting from electrical action and electrical activity resulting from chemical changes.Gene Expression Regulation, Bacterial: Any of the processes by which cytoplasmic or intercellular factors influence the differential control of gene action in bacteria.Bacterial Proteins: Proteins found in any species of bacterium.Plant Leaves: Expanded structures, usually green, of vascular plants, characteristically consisting of a bladelike expansion attached to a stem, and functioning as the principal organ of photosynthesis and transpiration. (American Heritage Dictionary, 2d ed)Carbonates: Salts or ions of the theoretical carbonic acid, containing the radical CO2(3-). Carbonates are readily decomposed by acids. The carbonates of the alkali metals are water-soluble; all others are insoluble. (From Grant & Hackh's Chemical Dictionary, 5th ed)Aerobiosis: Life or metabolic reactions occurring in an environment containing oxygen.Aldehyde Oxidoreductases: Oxidoreductases that are specific for ALDEHYDES.Cell Line, Tumor: A cell line derived from cultured tumor cells.Fatty Acids: Organic, monobasic acids derived from hydrocarbons by the equivalent of oxidation of a methyl group to an alcohol, aldehyde, and then acid. Fatty acids are saturated and unsaturated (FATTY ACIDS, UNSATURATED). (Grant & Hackh's Chemical Dictionary, 5th ed)Glycerol: A trihydroxy sugar alcohol that is an intermediate in carbohydrate and lipid metabolism. It is used as a solvent, emollient, pharmaceutical agent, and sweetening agent.Organic Chemicals: A broad class of substances containing carbon and its derivatives. Many of these chemicals will frequently contain hydrogen with or without oxygen, nitrogen, sulfur, phosphorus, and other elements. They exist in either carbon chain or carbon ring form.Oceans and Seas: A great expanse of continuous bodies of salt water which together cover more than 70 percent of the earth's surface. Seas may be partially or entirely enclosed by land, and are smaller than the five oceans (Atlantic, Pacific, Indian, Arctic, and Antarctic).Breast Neoplasms: Tumors or cancer of the human BREAST.

Sensitivity of [11C]phenylephrine kinetics to monoamine oxidase activity in normal human heart. (1/5742)

Phenylephrine labeled with 11C was developed as a radiotracer for imaging studies of cardiac sympathetic nerves with PET. A structural analog of norepinephrine, (-)-[11C]phenylephrine (PHEN) is transported into cardiac sympathetic nerve varicosities by the neuronal norepinephrine transporter and stored in vesicles. PHEN is also a substrate for monoamine oxidase (MAO). The goal of this study was to assess the importance of neuronal MAO activity on the kinetics of PHEN in the normal human heart. MAO metabolism of PHEN was inhibited at the tracer level by substituting deuterium atoms for the two hydrogen atoms at the alpha-carbon side chain position to yield the MAO-resistant analog D2-PHEN. METHODS: Paired PET studies of PHEN and D2-PHEN were performed in six normal volunteers. Hemodynamic and electrocardiographic responses were monitored. Blood levels of intact radiotracer and radiolabeled metabolites were measured in venous samples taken during the 60 min dynamic PET study. Myocardial retention of the tracers was regionally quantified as a retention index. Tracer efflux between 6 and 50 min after tracer injection was fit to a single exponential process to obtain a washout half-time for all left ventricular regions. RESULTS: Although initial heart uptake of the two tracers was similar, D2-PHEN cleared from the heart 2.6 times more slowly than PHEN (mean half-time 155+/-52 versus 55+/-10 min, respectively; P < 0.01). Correspondingly, heart retention of D2-PHEN at 40-60 min after tracer injection was higher than PHEN (mean retention indices 0.086+/-0.018 versus 0.066+/-0.011 mL blood/ min/mL tissue, respectively; P < 0.003). CONCLUSION: Efflux of radioactivity from normal human heart after uptake of PHEN is primarily due to metabolism of the tracer by neuronal MAO. Related mechanistic studies in the isolated rat heart indicate that vesicular storage of PHEN protects the tracer from rapid metabolism by neuronal MAO, suggesting that MAO metabolism of PHEN leaking from storage vesicles leads to the gradual loss of PHEN from the neurons. Thus, although MAO metabolism influences the rate of clearance of PHEN from the neurons, MAO metabolism is not the rate-determining step in the observed efflux rate under normal conditions. Rather, the rate at which PHEN leaks from storage vesicles is likely to be the rate-limiting step in the observed efflux rate.  (+info)

Reproducibility studies with 11C-DTBZ, a monoamine vesicular transporter inhibitor in healthy human subjects. (2/5742)

The reproducibility of (+/-)-alpha-[11C] dihydrotetrabenazine (DTBZ) measures in PET was studied in 10 healthy human subjects, aged 22-76 y. METHODS: The scan-to-scan variation of several measures used in PET data analysis was determined, including the radioactivity ratio (target-to-reference), plasma-input Logan total distribution volume (DV), plasma-input Logan Bmax/Kd and tissue-input Logan Bmax/Kd values. RESULTS: The radioactivity ratios, plasma-input Bmax/Kd and tissue-input Bmax/Kd all have higher reliability than plasma-input total DV values. In addition, measures using the occipital cortex as the reference region have higher reliability than the same measures using the cerebellum as the reference region. CONCLUSION: Our results show that DTBZ is a reliable PET tracer that provides reproducible in vivo measurement of striatal vesicular monoamine transporter density. In the selection of reference regions for DTBZ PET data analysis, caution must be exercised in circumstances when DTBZ binding in the occipital cortex or the cerebellum may be altered.  (+info)

Influence of vesicular storage and monoamine oxidase activity on [11C]phenylephrine kinetics: studies in isolated rat heart. (3/5742)

[11C]Phenylephrine (PHEN) is a radiolabeled analogue of norepinephrine that is transported into cardiac sympathetic nerve varicosities by the neuronal norepinephrine transporter and taken up into storage vesicles localized within the nerve varicosities by the vesicular monoamine transporter. PHEN is structurally related to two previously developed sympathetic nerve markers: [11C]-meta-hydroxyephedrine and [11C]epinephrine. To better characterize the neuronal handling of PHEN, particularly its sensitivity to neuronal monoamine oxidase (MAO) activity, kinetic studies in an isolated working rat heart system were performed. METHODS: Radiotracer was administered to the isolated working heart as a 10-min constant infusion followed by a 110-min washout period. Two distinctly different approaches were used to assess the sensitivity of the kinetics of PHEN to MAO activity. In the first approach, oxidation of PHEN by MAO was inhibited at the enzymatic level with the MAO inhibitor pargyline. In the second approach, the two hydrogen atoms on the a-carbon of the side chain of PHEN were replaced with deuterium atoms ([11C](-)-alpha-alpha-dideutero-phenylephrine [D2-PHEN]) to inhibit MAO activity at the tracer level. The importance of vesicular uptake on the kinetics of PHEN and D2-PHEN was assessed by inhibiting vesicular monoamine transporter-mediated storage into vesicles with reserpine. RESULTS: Under control conditions, PHEN initially accumulated into the heart at a rate of 0.72+/-0.15 mL/min/g wet. Inhibition of MAO activity with either pargyline or di-deuterium substitution did not significantly alter this rate. However, MAO inhibition did significantly slow the clearance of radioactivity from the heart during the washout phase of the study. Blocking vesicular uptake with reserpine reduced the initial uptake rates of PHEN and D2-PHEN, as well as greatly accelerated the clearance of radioactivity from the heart during washout. CONCLUSION: These studies indicate that PHEN kinetics are sensitive to neuronal MAO activity. Under normal conditions, efficient vesicular storage of PHEN serves to protect the tracer from rapid metabolism by neuronal MAO. However, it is likely that leakage of PHEN from the storage vesicles and subsequent metabolism by MAO lead to an appreciable clearance of radioactivity from the heart.  (+info)

Regional patterns of myocardial sympathetic denervation in dilated cardiomyopathy: an analysis using carbon-11 hydroxyephedrine and positron emission tomography. (4/5742)

OBJECTIVE: To assess presynaptic function of cardiac autonomic innervation in patients with advanced congestive heart failure using positron emission tomography (PET) and the recently developed radiolabelled catecholamine analogue carbon-11 hydroxyephedrine (HED) as a marker for neuronal catecholamine uptake function. DESIGN AND PATIENTS: 29 patients suffering from dilated cardiomyopathy with moderate to severe heart failure were compared with eight healthy controls. Perfusion scan was followed by HED dynamic PET imaging of cardiac sympathetic innervation. The scintigraphic results were compared with markers of disease severity and the degree of sympathetic dysfunction assessed by means of heart rate variability. RESULTS: In contrast to nearly normal perfusions, mean (SD) HED retention in dilated cardiomyopathy patients was abnormal in 64 (32)% of the left ventricle. Absolute myocardial HED retention was 10.7 (1.0)%/min in controls v 6.2 (1.6)%/min in dilated cardiomyopathy patients (p < 0.001). Moreover, significant regional reduction of HED retention was demonstrated in apical and inferoapical segments. HED retention was significantly correlated with New York Heart Association functional class (r = -0.55, p = 0. 002) and ejection fraction (r = 0.63, p < 0.001), but not, however, with plasma noradrenaline concentrations as well as parameters of heart rate variability. CONCLUSIONS: In this study, using PET in combination with HED in patients with dilated cardiomyopathy, not only global reduction but also regional abnormalities of cardiac sympathetic tracer uptake were demonstrated. The degree of abnormality was positively correlated to markers of severity of heart failure. The pathogenetic mechanisms leading to the regional differences of neuronal damage as well as the prognostic significance of these findings remain to be defined.  (+info)

Measurement of striatal D2 dopamine receptor density and affinity with [11C]-raclopride in vivo: a test-retest analysis. (5/5742)

Subacute and long-term stability of measurements of D2 dopamine receptor density (Bmax), affinity (Kd) was studied with positron emission tomography in eight healthy male volunteers. [11C]-Raclopride and the transient equilibrium method were used to measure D2 receptor characteristics. The interval between measurements (scan pairs) was 3 to 7 weeks (subacute) for four subjects and 6 to 11 months (long-term) for four subjects. A test-retest analysis of quantitative measurements of D2 receptor Bmax and Kd was compared with that done on binding potential (BP, Bmax/Kd) measures. In addition, the effect of error in defining the transient equilibrium time (tmax) in the parameter estimation procedure was explored with simulations. The subacute test-retest indicates good reproducibility of D2 receptor density, affinity, and BP ratio measurements with intraclass correlation coefficients of 0.90, 0.96, and 0.86, respectively. The variability of the measurements after 6 to 11 months was slightly higher than that seen in a subacute testing for Kd and more clearly so for binding potential and Bmax. The absolute variability in Bmax (14.5%) measurements was consistently higher than that of Kd (8.4%) or BP (7.9%) both in subacute and long-term measurements. Simulations indicated that the Bmax and Kd estimation procedure is more sensitive to error in the tmax than that for the BP. The results indicate a good overall stability of the equilibrium method with [11C]raclopride for measuring dopamine D2 receptor binding characteristics in the striatum. The BP approach is more stable than Kd and especially Bmax measurements. Error in defining the tmax in particular in the low specific radioactivity scan may be one source of greater variability in Bmax versus BP. However, a higher intraindividual variability in measurements of the D2 receptor Bmax also may include a component of continuous regulation of this parameter over time. These methodologic aspects should be considered in the design and interpretation of longitudinal studies on D2 dopamine receptor characteristics with [11C]-raclopride.  (+info)

Novel, highly lipophilic antioxidants readily diffuse across the blood-brain barrier and access intracellular sites. (6/5742)

In an accompanying article, an in vitro assay for permeability predicts that membrane-protective, antioxidant 2,4-diamino-pyrrolo[2, 3-d]pyrimidines should have improved blood-brain barrier (BBB) permeation over previously described lipophilic antioxidants. Using a first-pass extraction method and brain/plasma quantification, we show here that two of the pyrrolopyrimidines, one of which is markedly less permeable, readily partition into rat brain. The efficiency of extraction was dependent on serum protein binding, and in situ efflux confirms the in vitro data showing that PNU-87663 is retained in brain longer than PNU-89843. By exploiting inherent fluorescence properties of PNU-87663, its distribution within brain and within cells in culture was demonstrated using confocal scanning laser microscopy. PNU-87663 rapidly partitioned into the cell membrane and equilibrates with cytoplasmic compartments via passive diffusion. Although partitioning of PNU-87663 favors intracytoplasmic lipid storage droplets, the compound was readily exchangeable as shown by efflux of compound from cells to buffer when protein was present. The results demonstrated that pyrrolopyrimidines were well suited for quickly accessing target cells within the central nervous system as well as in other target tissues.  (+info)

Absorption, metabolism, and excretion of 14C-temozolomide following oral administration to patients with advanced cancer. (7/5742)

The purpose of this study is to characterize the absorption, metabolism, and excretion of carbon 14-labeled temozolomide (14C-TMZ) administered p.o. to adult patients with advanced solid malignancies. On day 1 of cycle 1, six patients received a single oral 200-mg dose of 14C-TMZ (70.2 microCi). Whole blood, plasma, urine, and feces were collected from days 1-8 and on day 14 of cycle 1. Total radioactivity was measured in all samples. TMZ, 5-(3-methyltriazen-1-yl)imidazole-4-carboxamide (MTIC), and 4-amino-5-imidazole-carboxamide (AIC) concentrations were determined in plasma, and urine and plasma samples were profiled for metabolite/degradation products. Maximum TMZ plasma concentrations were achieved between 0.33 to 2 h (mean, 1.2 h), and half-life, apparent volume of distribution, and oral clearance values averaged 1.9 h, 17 liters/m2, and 104 ml/min/m2, respectively. A first-order absorption, one-compartment linear model, which included first-order formation of MTIC from TMZ and elimination of MTIC via degradation to AIC, and a peripheral distribution compartment for AIC, adequately described the plasma TMZ, MTIC, and AIC concentrations. MTIC systemic clearance was estimated to be 5384 ml/min/m2, and the half-life was calculated to be 2.5 min. Metabolite profiles of plasma at 1 and 4 h after treatment showed that 14C-derived radioactivity was primarily associated with TMZ, and a smaller amount was attributed to AIC. Profiles of urine samples from 0-24 h revealed that 14C-TMZ-derived urinary radioactivity was primarily associated with unchanged drug (5.6%), AIC (12%), or 3-methyl-2,3-dihydro-4-oxoimidazo[5,1-d]tetrazine-8-carboxyl ic acid (2.3%). The recovered radioactive dose (39%) was principally eliminated in the urine (38%), and a small amount (0.8%) was excreted in the feces. TMZ exhibits rapid oral absorption and high systemic availability. The primary elimination pathway for TMZ is by pH-dependent degradation to MTIC and further degradation to AIC. Incomplete recovery of radioactivity may be explained by the incorporation of AIC into nucleic acids.  (+info)

Genetic evidence for ATP-dependent endoplasmic reticulum-to-Golgi apparatus trafficking of ceramide for sphingomyelin synthesis in Chinese hamster ovary cells. (8/5742)

LY-A strain is a Chinese hamster ovary cell mutant resistant to sphingomyelin (SM)-directed cytolysin and has a defect in de novo SM synthesis. Metabolic labeling experiments with radioactive serine, sphingosine, and choline showed that LY-A cells were defective in synthesis of SM from these precursors, but not syntheses of ceramide (Cer), glycosphingolipids, or phosphatidylcholine, indicating a specific defect in the conversion of Cer to SM in LY-A cells. In vitro experiments showed that the specific defect of SM formation in LY-A cells was not due to alterations in enzymatic activities responsible for SM synthesis or degradation. When cells were treated with brefeldin A, which causes fusion of the Golgi apparatus with the endoplasmic reticulum (ER), de novo SM synthesis in LY-A cells was restored to the wild-type level. Pulse-chase experiments with a fluorescent Cer analogue, N-(4,4-difluoro-5,7-dimethyl-4-bora-3a, 4a-diaza-s-indacene-3-pentanoyl)-D-erythro-sphingosine (C5-DMB-Cer), revealed that in wild-type cells C5-DMB-Cer was redistributed from intracellular membranes to the Golgi apparatus in an intracellular ATP-dependent manner, and that LY-A cells were defective in the energy-dependent redistribution of C5-DMB-Cer. Under ATP-depleted conditions, conversion of C5-DMB-Cer to C5-DMB-SM and of [3H]sphingosine to [3H]SM in wild-type cells decreased to the levels in LY-A cells, which were not affected by ATP depletion. ER-to-Golgi apparatus trafficking of glycosylphosphatidylinositol-anchored or membrane-spanning proteins in LY-A cells appeared to be normal. These results indicate that the predominant pathway of ER-to-Golgi apparatus trafficking of Cer for de novo SM synthesis is ATP dependent and that this pathway is almost completely impaired in LY-A cells. In addition, the specific defect of SM synthesis in LY-A cells suggests different pathways of Cer transport for glycosphingolipids versus SM synthesis.  (+info)

A graphical method of analysis applicable to ligands that bind reversibly to receptors or enzymes requiring the simultaneous measurement of plasma and tissue radioactivities for multiple times after the injection of a radiolabeled tracer is presented. It is shown that there is a time t after which a …
W. P. T. James, P. J. Garlick, P. M. Sender; Studies of Protein Metabolism in Man with Infusions of [14C]Tyrosine. Clin Sci Mol Med 1 January 1974; 46 (1): 8P. doi: https://doi.org/10.1042/cs046008Pa. Download citation file:. ...
For some reason, which I have not yet figured out, at least one person per week has been asking me about the Carbon-14 Radiometric Dating Technique. They want to know if it is accurate or if it works at all. Worse still, sometimes they want to know how evolutionists use Carbon-14 to date dinosaur fossils!. The word radiometric as used in this article refers to the supposed use of the decay of radioactive chemical isotopes to supposedly measure the amount of time that has elapsed since an event occurred or a creature lived. Radiometric Dating Technologies are presented to the public by evolutionists as utterly reliable clocks for dating earth rocks or biological materials. There are more than 80 such technologies that are claimed to work. Carbon-14 is the best known of all these methods.. Prior to looking at the many flaws in the Carbon-14 Dating Technique, it should be noted that no radiometric technique is reliable. They all start with similar flaws, but Carbon-14 has more than the rest.. Many ...
Use the "nitrogen tree": Turn heat on high. Set pressure regulator on tank to 2-4 psi. Flow gauge should read 8 L/min for two samples. Clean capillary tips with ethanol, unscrew white plastic, move metal shaft down (may need to wipe with ethanol to allow this), insert capillary tip into glass sample vial (close to liquid but not touching), screw plastic threading back to lock the metal shaft in place. Leave heating block on. Move sample vial up hourly as liquid evaporates ...
Use the "nitrogen tree": Turn heat on high. Set pressure regulator on tank to 2-4 psi. Flow gauge should read 8 L/min for two samples. Clean capillary tips with ethanol, unscrew white plastic, move metal shaft down (may need to wipe with ethanol to allow this), insert capillary tip into glass sample vial (close to liquid but not touching), screw plastic threading back to lock the metal shaft in place. Leave heating block on. Move sample vial up hourly as liquid evaporates ...
The 993-994 carbon-14 spike was a rapid increase in carbon-14 content from tree rings, and followed the 774-775 carbon-14 spike.[1] This event is also confirmed by a sharp increase of beryllium-10 and hence considered as solar-origin. [2] It may have come from a massive solar storm as a series of auroral observations are known to be observed in late 992. [3]. ...
Imagine my surprise when the "lump" on the left turned out to be nothing but they found "something" on the right. I was told to track down my old scans from a previous doc/clinic so they could do a comparison. Was this a new something? Or something that has always been there and just disregarded. Fine. It wasnt easy tracking down my baseline scans. The clinic had been sold and changed hands a couple times, but we got them ...
TY - JOUR. T1 - Improved preparation of l-[Methyl-11C]methionine by on-line [11C]methylation. AU - Mizuno, Ken Ichiro. AU - Yamazaki, Shigeki. AU - Iwata, Ren. AU - Pascali, Claudio. AU - Ido, Tatsuo. PY - 1993. Y1 - 1993. N2 - On-line [11C]methylation using [11C]methyl iodide has been successfully applied to the preparation of l-[methyl-11C]-methionine (11C-Met). [11C]Methyl iodide is first trapped in a short column that contains Porapak Q and l-homocysteine thiolactone coated on inert support. The column is then charged with NaOH dissolved in a mixture of ethanol and water to cause the [11C]methylation. The present method can provide practically pure 11C-Met in radiochemical yield of over 98%. The whole procedure including the sterilization of final product has been completely automated for routine PET use.. AB - On-line [11C]methylation using [11C]methyl iodide has been successfully applied to the preparation of l-[methyl-11C]-methionine (11C-Met). [11C]Methyl iodide is first trapped in a ...
1. Plasma amino acid kinetics were determined in hospitalized patients receiving one of three intravenous solutions: isotonic amino acids, isotonic sodium chloride, or total parenteral nutrition.. 2. Whole body amino acid appearance, oxidation and incorporation into protein were estimated with two different isotopically labelled amino acids: l-[1-14C]leucine and l-[U-14C]tyrosine.. 3. A positive correlation was obtained between whole body amino acid appearance, oxidation and incorporation into protein with the two isotopically labelled amino acids.. 4. Derivation of whole body protein kinetics with l-[U-14C]tyrosine consistently gave higher values than those obtained from l-[1-14C]leucine, presumably due in part to the contribution of phenylalanine hydroxylation to plasma tyrosine appearance. However, the percentages of amino acid appearance oxidized and used for protein synthesis were similar.. 5. It can be concluded that estimates of whole body protein kinetics are qualitatively similar when ...
Hyperpolarized carbon-13 MRI is a functional medical imaging technique for probing perfusion and metabolism using injected substrates. It is enabled by techniques for hyperpolarization of carbon-13-containing molecules using dynamic nuclear polarization and rapid dissolution to create an injectable solution. Following the injection of a hyperpolarized substrate, metabolic activity can be mapped based on enzymatic conversion of the injected molecule. In contrast with other metabolic imaging methods such as positron emission tomography, hyperpolarized carbon-13 MRI provides chemical as well as spatial information, allowing this technique to be used to probe the activity of specific metabolic pathways. This has led to new ways of imaging disease. For example, metabolic conversion of hyperpolarized pyruvate into lactate is increasingly being used to image cancerous tissues via the Warburg effect. While hyperpolarization of inorganic small molecules (like 3He and 129Xe) is generally achieved using ...
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Environmentally Safe|br| Biodegradable|br| Non-toxic|br|•Non-flammable|br|Primary Applications: Aqueous samples from 0 to 15% count as monophasic solutions. High ionic concentrations will be most efficiently counted in this region. Also, for use under controlled chemiluminescence when high tritium efficiency is desired.
View Notes - Lecture_Notes_103009b from CHEM 105BLG at USC. Dating by Radioactivity Carbon Dating takes advantage of the decay of carbon-14 which has a half-life of 5730 years What percentage of C-14
I was also a bit confused with what you meant by baseline scan. From what I understand of the IVF treatment I had, after downregging they do a scan to check your uterus lining is thin, to show your system is effectively shutdown.They can then take control of your cycle by starting the stimulating injections. Its at this point after a few days you should be producing follicles. My first scan after starting stimulating injections showed no response at all. (Cant remember exactly how many days after starting stimming, but at least 4 or 5 days I think). They then more than doubled my dose of stimming drugs (I was on Gonal F). I did start to respond, but slowly at first and there were only 8 follicles a week before EC. 3 days before EC I had responded more and had a few more follicles, but they didnt know if some would be big enough. They collected 12 eggs on EC day. I dont know if this helps, but from my experience things can change by EC day ...
radiocarbon dating of plants and animals.how many years will it take for carbon-14 to diminish to 1 of the original, Hire Chemistry Expert, Ask Academics Expert, Assignment Help, Homework Help, Textbooks Solutions
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维生素C治疗坏血病是250年来医学证实的事实。坏血病是长期缺乏维生素C的最终病况,它在人体上的表现是极度疲乏、肌肉无力、皮肤肿胀疼痛、牙龈出血、口臭、皮下及肌肉中血管破裂出血、关节软弱、骨骼脆弱以致骨折、虚脱、泻痢、肺脏及肾脏衰竭而导致昏迷以致死亡。由此可见维生素C对各个主要器官都有影响。[60][61][62] 腎上腺是人體含維生素C最高的器官。人體在緊張的時候,腎上腺分泌大量的腎上腺素到全身的肌肉中,準備好隨時動作,應付危機。腎上腺素是從酪氨酸(Tyrosine)制成多巴(Dopa),轉化成多巴胺(Dopamine),再轉化為降腎上腺素(Noradrenaline),最后制成腎上腺素。其中每一步驟都要消耗維生素C進行羥基化反應(Hydroxylation)。這是人和動物的腎上腺必須儲備大量維生素C的原因。[63][64] ...
The purpose of this study is to assess the mass balance (that is, cumulative excretion of total radioactivity [TRA] in urine and feces) of pevonedistat
The Quantulus GCT 6220 is a liquid scintillation counter (LSC) for ultra low-level sensitivity, in a lighter benchtop footprint to fit any lab.
The Quantulus GCT 6220 is a liquid scintillation counter (LSC) for ultra low-level sensitivity, in a lighter benchtop footprint to fit any lab.
I went in for my baseline scan today as Big Red showed up right on time on Tuesday. Normally the baseline scan I have done is for an IUI to see if the roiding from the last cycle had sufficiently quieted down. This time it was to see if my ovaries were in nice Lupron-induced…
Radioactivity is a process of emission of radiation and energy from unstable nuclei in order to form more stable atoms. What is radioactivity? What are its applications? Read on to find out.
For over 65 years, PerkinElmer has been a leading provider and partner for radiometric detection solutions ranging from instruments and radiochemicals, to liquid scintillation cocktails, vials, and microplates.
It has generally been recognized that molecular diffusion can be a significant process affecting the transport of carbon-14 in the subsurface when occurring either from a permeable aquifer into a confining layer or from a fracture into a rock matrix. An analytical solution that is valid for steady-state radionuclide transport through fractured rock is shown to be applicable to many multilayered aquifer systems. By plotting the ratio of the rate of diffusion to the rate of decay of carbon-14 over the length scales representative of several common hydrogeologic settings, it is demonstrated that diffusion of carbon-14 should often be not only a significant process, but a dominant one relative to decay. An age-correction formula is developed and applied to the Bangkok Basin of Thailand, where a mean carbon-14-based age of 21,000 years was adjusted to 11,000 years to account for diffusion. This formula and its graphical representation should prove useful...
BioAssay record AID 629721 submitted by ChEMBL: Displacement of [3H]-8-OH-DPAT from 5-HT1A receptor in rat hippocampus by liquid scintillation counting.
Clinical studies have shown that the absorption of an oral dose of thioguanine in humans is incomplete and variable, averaging approximately 30% of the administered dose (range: 14% to 46%). Following oral administration of 35S-6-thioguanine, total plasma radioactivity reached a maximum at 8 hours and declined slowly thereafter. Parent drug represented only a very small fraction of the total plasma radioactivity at any time, being virtually undetectable throughout the period of measurements.. The oral administration of radiolabeled thioguanine revealed only trace quantities of parent drug in the urine. However, a methylated metabolite, 2-amino-6-methylthiopurine (MTG), appeared very early, rose to a maximum 6 to 8 hours after drug administration, and was still being excreted after 12 to 22 hours. Radiolabeled sulfate appeared somewhat later than MTG but was the principal metabolite after 8 hours. Thiouric acid and some unidentified products were found in the urine in small amounts. Intravenous ...
Several previous retrospective studies of MET-PET for BM focused on its diagnostic accuracy and provided an optimal cut-off value for diagnosis but, unfortunately, did not provide subsequent management details. Such specific details are often of critical importance to physicians caring for BM patients. The authors sought to provide information useful for physicians on how to manage such refractory situations, by investigating not only the diagnostic accuracy of MET-PET but also the long-term results of salvage management. We believe this novel viewpoint to be the core value of the present work.. This is the first report to demonstrate that MET-PET can predict the patients survival as well as providing the immediate diagnosis. This exploratory insight has, in our opinion, clinical significance and can be regarded as relevant because RN follows a self-limited course in most cases while, in contrast, LR can lead to neurological death. In fact, we observed that 9 patients diagnosed with LR on ...
Background. Heterogeneity in regional left ventricular function has long been noted in patients with nonischemic dilated cardiomyopathy. Regional variation in wall stress has been proposed as the pathophysiologic mechanism. By correlating regional function with oxidative metabolism, one can test the hypothesis that heterogeneity in wall stress is responsible for heterogeneity in function. We hypothesized that preserved function as a result of more favorable loading conditions would be associated with regional oxidative metabolism that is equal to or lower than that in other regions. ...
Both evolutionists and creationists stand in agreement that radiocarbon dating, which can be used only to date organic samples, is totally ineffective in measuring the alleged millions or billions of years of the evolutionary timetable. [In truth, even when dating things that are relatively young, carbon-14 dating is imperfect and based upon certain unprovable assumptions (see Major, 1993).] If radiocarbon dating can measure only items that are thousands of years old, why should evolutionists even consider using this dating method on anything that they already believe to be millions of years old? Creationists would like to see evolutionists apply this method to items believed to be millions of years old, because it might help convince evolutionists that coal, diamonds, fossils, etc. are not millions of years old, but only thousands of years old.. Consider that in recent years "readily detectable amounts of carbon-14" in materials evolutionists suppose are millions of years old "have been the ...
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definition of IDVG, what does IDVG mean?, meaning of IDVG, Initial Distribution Volume of Glucose, IDVG stands for Initial Distribution Volume of Glucose
You have 5 grams of carbon-14; whose half-life is 5730 years. a)Write the rule of the function that gives the amount of carbon-14 remaining after x years. b)How much carbon-14 will be left after 4,000 years ...
FlashPlate® is a white polystyrene microplate, designed for high-volume, homogeneous radiometric assays, based upon the principle of scintillation proximity. The interior of each well is permanently coated with a thin layer of polystyrene-based scintillant which provides a platform for non-separation assays using a variety of isotopes (e.g.,3H, 125I, 14C and 33P) without the addition of liquid scintillation cocktail. FlashPlate is available in both 96-well and 384-well formats.. ...
Description: Tumor doubling time was estimated using an exponential growth model. Specifically, the pre-progression scan, and the baseline scan were used to estimate the doubling time prior to enrollment, td = log(2)∗1time/1log(tumor size) [derivation, S(t) = S(to)∗2∧[(t−to)/td] for a parameterization of exponential growth with a doubling time of td. Taking the logarithm on both sides: log(S(t))-log(S(to)) = log(2)∗(t − to)/td or td = log(2)∗(t − to)/[log(S(t))-log(S(to))] = log(2)∗1time/1log(S)], the baseline scan and first evaluation scan were used to determine the doubling time. Based on pre-planned protocol assessment, we estimated the percent of patients that experienced a slowing of tumor kinetics (a 30% increase in the length of time for tumor doubling) based on RECIST v1.1 measurements. Patients who did not get a scan on study, and patients whose pre-progression scans were missing or whose pre-progression tumor size was zero or whose tumor was decreasing prior to ...
Pico-Fluor Plus is a NPE free Liquid Scintillation Cocktail featuring high sample load capacity for aqueous samples and buffer solutions, dompatibility with alkaline tissue solubilizers, compatibility and no background with alkaline sample material, and relatively high Counting efficiency for tritium. ...
Handling Live Cultured Cells Keep a flask with 20 ml existing medium in 37°C CO2 incubator for 1 hour before replacing the medium. Either split the 90% confluent cells from a T25 flask to a T75 flask after 1 hour or let the cells grow in the T25 flask for 12-24 hours before split the cells to a T75 flask. Cells should be checked daily under a microscopy to verify appropriate cell morphology. ...
Accelerator mass spectrometry (AMS) is currently the most sensitive method for trace DNA adduct detection. O6-Mehtyldeoxyguanosine (O 6-MedG) is a strongly mutagenic lesion formed by a variety of alkylating agents. For this reason this was the adduct of choice for use in this study, the aim of which was to develop a 14C-postlabelling technique, involving incorporation of radiolabel onto O6-MedG adducts after isolation, thus enabling exploitation of AMS to detect low levels of adducts without the need to administer a 14C-labelled compound. A method was developed and optimised for acetylating O6-MedG, in , 90% yields. This method was then used to acetylate the adduct with 14C-acetic anhydride, but changes required for the safe handling of radiolabelled compound altered the reaction product profile, resulting in the major derivative being 14C-di-acetyl O6-MedG, (38% yield). This pure standard was used to determine detection limits of 1.4 pmoles of adduct using HPLC and liquid scintillation counting ...
OBJECTIVE: The serotonin transporter (5-HTT) is a key target for selective serotonin reuptake inhibitors and may be involved in the pathophysiology of major depression. It is now possible to image 5-HTT directly in the human brain, but results from studies of acutely depressed patients have been inconsistent. The purpose of this study was to determine whether abnormalities in 5-HTT might be present in recovered depressed patients. METHOD: The authors measured the binding potential of 5-HTT using [11C]DASB in conjunction with positron emission tomography (PET) in 24 medication-free, recovered depressed male patients and 20 healthy male comparison subjects. The regional estimates of binding potential were obtained using a metabolite-corrected plasma input function method followed by Logan analysis, with the cerebellum as a reference region. RESULTS: The authors found no significant difference in the binding potential of [11C]DASB between the recovered depressed patients and healthy comparison subjects in
The Tri-Carb 4910TR liquid scintillation counter provides the popular standard features needed for research applications and the versatility to expand for environmental analysis with the optional ultralow-level and alpha/beta discrimination features.. The Tri-Carb 4910TR liquid scintillation counter provides high performance and flexibility for multi-application and multi-user laboratories detecting radioactivity in life science research, environmental monitoring and/or health physics assays. Optional Packages are available for High Sensitivity Counting of low activity samples and Alpha Beta Separation for unknown or mixed samples.. Exclusive Standard Features. ...
1. By using dl-[ring−14C]phenylalanine, dl-[β−14C]phenylalanine, dl-[α−14C]-tyrosine and dl-[β−14C]tyrosine it was shown that in maize shoots (Zea mays) the nucleus and one nuclear methyl group of each of the following compounds, plastoquinone, γ-tocopherol (aromatic nucleus) and α-tocopherolquinone, are formed from the nuclear carbon atoms and β-carbon atom respectively of either exogenous phenylalanine or exogenous tyrosine. With ubiquinone only the aromatic ring of the amino acid is used in the synthesis of the quinone nucleus. Chemical degradation of plastoquinone and γ-tocopherol molecules labelled from l-[U−14C]tyrosine established that a C6-C1 unit directly derived from the amino acid is involved in the synthesis of these compounds. Radioactivity from [β−14C]cinnamic acid is not incorporated into plastoquinone, tocopherols or tocopherolquinones, demonstrating that the C6-C1 unit is not formed from any of the C6-C1 phenolic acids associated with the metabolism of this ...
The PET Facility at the University of Pittsburgh has been operational since 1992, and is administered as a research division of the Department of Radiology under the direction of Chester A Mathis, Ph.D. The PET Facility is housed in over 12,000 square feet of the 9th floor of the B-wing in Presbyterian-University Hospital, University of Pittsburgh Medical Center (UPMC) Health System. This space includes three scanner bays serviced by two control rooms, inpatient and outpatient preparation rooms, and a small wet laboratory outfitted with an array of radiation detection instrumentation for blood and radiolabeled metabolite assays. The PET Radiochemistry Laboratory is included within the PET Facility and is divided into a cold chemistry laboratory of 1000 sq. ft., a hot radiochemistry laboratory of 1000 sq. ft., and a 1200 sq. ft. cyclotron vault that houses a Siemens Eclipse HP medical cyclotron and ancillary supporting electronics and equipment. Research investigators, students, and PET Facility ...
Recent epidemiological research and pet experiments have proven that non-steroidal anti-inflammatory drugs (NSAIDs) decrease the incidence of colorectal carcinoma. the steroid receptor superfamily. PPAR- is important in both adipocyte differentiation and carcinogenesis. PPAR- is definitely one focus on for cell development modulation of NSAIDs. With this review, we record the manifestation of COX-2, LOX and PPAR- in human being prostate cancer cells aswell as the consequences of COX-2 and LOX inhibitors and PPAR- ligand. solid course="kwd-title" Keywords: cyclooxygenase, lipoxygenase, peroxisome proliferator activator-receptor-, prostate tumor Introduction Prostate tumor (Personal computer) includes 32% of most malignancies in American males and is within the boost worldwide. Due to increased screening, Personal computer is generally diagnosed at a medically localized stage, rendering it amenable to the treatment. Nevertheless, it continues to be the next most common reason behind cancer loss of ...
Measurement of Radioactivity. Total radioactivity in liquid samples [plasma, urine and bile (BDC rats only)] from all species was determined by liquid scintillation counting using a Tri-Carb 2500A liquid scintillation spectrometer (Canberra Packard, Groningen, The Netherlands). Samples were made up to 1 ml with distilled water, if necessary, and prepared for radioanalysis by the addition of Ultima Gold scintillation cocktail. Solid samples (feces) were homogenized, lyophilized, homogenized again, and combusted using the Canberra Packard System 387 (Oxidizer Tri-Carb 307 and Robot System 80). The formed 14CO2 was trapped in Carbo-Sorb and topped up with scintillation cocktail (Permafluor E+) before radioanalysis.. Metabolite Profiling. Metabolite patterns in plasma, urine, and feces from all species and in bile from BDC rats were determined using high-performance liquid chromatography (HPLC) with on-line radioactivity detection (Ramona 5; Raytest GmbH, Straubenhardt, Germany) or off-line ...
ACETYL TRIBUTYL CITRATE (ATBC) Primary Plasticizer for PVC and PVC copolymers Chemical Nature Chemical Name :- 2-acetyl-1,2,3-Propane tri carboxylic acid Tributyl Ester Trade Name :- ATBC Molecular Formula :- C 20 H 34 O 8 Molecular Weight :- 402.5 H 2 C - CO 2 C 4 H 9 C 2 H 5 CO 2 - C - CO 2 C 4 H 9 H 2 C - CO 2 C 4 H 9 CAS Number :- 77-90-7 UN ...
Acetyl-L-carnitine HCL is a mitochondrial metabolite that facilitates the movement of fatty acids into the mitochondria for energy and is also used to generate acetyl coenzyme A. ...
Chromatography of gaese with U-ECD, NPD and FPD Chromatography of gases coupled with mass spectrometry, Liquid chromatography with Post Column derivation and fluoroescence detector, Liquid chromatography with an arrangement of diodes ,Liquid scintillation ...
Formula: C23H22O7 MW: 410. 42 TNP NUMBER: TNP00188 MDL NUMBER: MFCD02184614 IUPAC: 2-(2-hydroxy-1-methyleneethyl)-8,9-dimethoxy-1,2-dihydrochromano[3,4-b]furano[ 2,3-h]chroman-6-one Smiles: c1(cc2c(cc1OC)OCC1C2C(c2c(O1)c1c(cc2)OC(C1)C(CO)=C)=O)OC ACCEPTORS: 7 DONORS: 1 ROTATION BONDS: 5 N+O: 7 Chiral Centers: 3 LogP: 3....
1 Click Chemistry Suppliers ,,(4-methylfuran-2-yl)methanol,OCC1=CC(C)=CO1,C6H8O2,MFCD25459267,(4-methylfuran-2-yl)methanolfor your research needs
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Looking for Positron-emission tomography? Find out information about Positron-emission tomography. see PET scan PET scan or positron emission tomography , a medical imaging technique that monitors metabolic, or biochemical, activity in the brain and other... Explanation of Positron-emission tomography
Periodical: Sokoloff, Louis, Martin Reivich, Charles Kennedy, M. H. Des Rosiers, C. S. Patlak, K. D. Pettigrew, O. Sakurada, and M. Shinohara. The [14C]Deoxyglucose Method for the Measurement of Local Cerebral Glucose Utilization: Theory, Procedure, and Normal Values in the Conscious and Anesthetized Albino Rat. Journal of Neurochemistry 28, 5 (1977): 897-916. Article. 20 Images ...
The department Accelerator Mass Spectrometry (AMS) and Isotope Research conducts interdisciplinary research in a broad application spectrum ranging from nuclear astrophysics to environment and biomedical applications utilizing natural and anthropogenic fingerprints of rare isotropes and trace elements. In addition, the technological advancement of AMS to new isotopes is pursued.
The ability of accelerator mass spectrometry (AMS) to measure very small concentrations of the nuclides 10 Be, 14 C, 26 Al, 36 Cl, and 129 I has led to many innovative applications in geologic research. To take advantage of this opportunity in the geosciences, it is important to understand how AMS works, how these nuclides are produced, and how they can be applied to geologic problems. We first discuss the basics of AMS, explaining what gives the method its ability to count small numbers of these nuclides. We review how these nuclides are produced and transported in the atmosphere, hydrosphere, and lithosphere. We then explain the ways that AMS is being used to solve a wide range of problems in geologic research by discussing specific applications in areas such as geomorphology, tectonics, climatology, hydrology, and geochronology.
Accelerator mass spectrometry (AMS) is a powerful method for the measurement of very low abundance nuclei (10-9 to 10-16) even in a background of much stronger isobars.
The National Resource for Accelerator Mass Spectrometry (AMS) was established in 1999 to enable biomedical researchers to accurately quantify very low levels of...
Radiocarbon refers to a radioactive isotope of carbon. Neutrons from sunrays collide with nitrogen in Earths upper atmosphere to form radiocarbon, which steadily emits beta particles until it all reverts to stable nitrogen. The calculated shelf life for radiocarbon atoms does not exceed 100,000 years. Thus, detectable radiocarbon within a given sample would become nitrogen before then.1. Scientists expect no radiocarbon in samples they deem older than 100,000 years. Most dating experts call these materials "carbon dead" regardless of their actual radiocarbon content. Then they use low (but not dead) radiocarbon materials as background blanks.2 Most results on this chart show fewer than 47,000 carbon years-the age of many labs background blanks. Thus, nearly 60 samples of fossils (mostly bone), wood, coal, and marble not only fail to fit their evolutionary ages, but they have more radiocarbon than the supposedly carbon- depleted background.. Scientists expect no radiocarbon in samples they deem ...
Beryllium dating is used to estimate the time a rock has been exposed on the surface of the Earth, as well as erosion and sedimentation rates.. Beryllium-10 is another cosmogenic nuclide. Like carbon-14, most of it is formed in the earths upper atmosphere. After formation, beryllium-10 binds to atmospheric dust particles or dissolves in atmospheric water vapor. It is transported to earth surface in rain so consequently it has a much shorter atmospheric residence time than carbon-14. It accumulates on the earths surface and depending upon the sedimentation regime in the local environment, it can be used to date surface accumulation rates, surface erosion rates, or for dating layers within ice cores. Its half-life is 1.39 million years.. Vanishingly small amounts of beryllium-10, carbon-14 and aluminum-26 are also created at the earths surface. The creation occurs within minerals the upper meter of rocks exposed directly to the sky. If rocks are undisturbed for millennia, differences in the ...
Adrenocortical cancer (ACC) is a rare disease that is often difficult to diagnose, and therefore often presents at an advanced stage. Various cytotoxic treatments have been tried with little success. Evaluation of new diagnostic methods and improvement of medical therapies are therefore crucial.. The diagnostic potential of 11C-metomidate positron emission tomography (PET) was evaluated in eleven ACC patients. PET visualized all viable tumors with high tracer uptake, including two lesions that CT failed to detect. Necrotic or fibrotic tumors were PET negative. Medication with adrenal steroid inhibitors and chemotherapy may decrease the tracer uptake.. We performed a phase-II study with streptozocin and o,p-DDD (SO) combination therapy in 40 ACC patients. The SO therapy was found to have impact on the disease-free interval (P = 0.02) as well as on survival (P = 0.01) in patients who received adjuvant therapy after curative resection. Complete or partial response was obtained in 36.4% of patients ...
Radiocarbon dating. A tiny sample of amino acids from a bone being combusted in oxygen prior to being radiocarbon dated. The carbon in the bone is converted to carbon dioxide gas, which then is assessed to measure the ratio between the radioactive isotope carbon-14 (14C) and the stable carbon-12 (12C) isotope in the gas. The ratio of 14C to 12C may be related to the time since the death of the animal or plant being investigated. Convention states that 14C has a half-life of 5568 years (+/- 30 years), although this is now thought to be too short. Dates from the process are given either as radiocarbon dates, or as solar dates after various corrections have been made. - Stock Image H170/0032
Two Sources. Carbon-14 comes from two sources: (1) the upper atmosphere where cosmic rays convert nitrogen-14 to about 21 pounds of carbon-14 per year, and (2) the earths crust where some neutron-heavy radioisotopes produce "cluster decay" by emitting small amounts of carbon-14 nuclei.2 The first source is widely known; few are aware of the second, which was discovered in 1984. As explained in The Origin of Earths Radioactivity on pages 387-441, neutron-heavy and superheavy radio isotopes were produced in abundance during the flood, so when those isotopes escaped into the atmosphere and decayed, some unknown but significant quantity of carbon-14 was released. Smaller, but also unknown, amounts of carbon-14 are still escaping from the crust.3 Most carbon-14 in the atmosphere quickly combines with oxygen to form radioactive carbon dioxide. Plants can then take in carbon dioxide, incorporating in their tissues both carbon-14 (radioactive) and normal carbon-12 (non-radioactive) in the same ...
In 1940 Martin Kamen discovered radioactive carbon-14 (an isotope of carbon) and found that it had a half-life of about 5,700 years. Scientists had also found that some of the nitrogen in the atmosphere was turned into carbon-14 when hit with cosmic rays. Thus, an equilibrium was reached, the newly formed carbon-14 replacing the carbon-14 that decayed, so that there was always a small amount in the atmosphere.. In 1947 American chemist Willard Libby (1908-1980) figured that plants would absorb some of this trace carbon-14 while they absorbed ordinary carbon in photosynthesis. Once the plant died, of course, it couldnt absorb any more carbon of any kind, and the carbon-14 it contained would decay at its usual rate without being replaced. By finding the concentration of carbon-14 left in the remains of a plant, you could calculate the amount of time since the plant had died. With this technique scientists could determine the age of plant-based artifacts -- wood, parchment, textiles -- up to ...
More protons than electrons: positive (+ve) charge. Unless it is important to distinguish between isotopes, it is common to use only the element symbol and the Charge. Isotopes Two atoms of the same element can have different numbers of neutrons These atoms would therefore have a different mass number. Atoms of the same element that have different mass numbers are called Isotopes. Carbon has 3 naturally occurring isotopes Carbon-12 : C 12 6 The nuclide symbol is This form of carbon has 6 protons and 6 neutrons. The 12 represents the mass number. Carbon-13 : C 13 6 The nuclide symbol is 6 protons and 7 neutrons. Much rarer than carbon-12 Carbon-12 and carbon-13 are the two stable isotopes of carbon. Carbon-14 C 14 6 The nuclide symbol is 6 protons and 8 neutrons. The only naturally occurring radio-isotope of carbon. (Radioactive) Used in carbon dating. N = A - Z Atomic Mass Units (amu or u) Defined using the mass of the carbon-12 atom. 1 carbon-12 atom has a mass of 12 amu 1 proton has a mass of ...
BioAssay record AID 271160 submitted by ChEMBL: Binding affinity to human PNMT expressed in Escherichia coli by radiochemical assay.
The metabolism and excretion of cabozantinib and its metabolites was studied in 8 healthy male volunteers who received a single oral dose of 140-mg cabozantinib FBE containing 100 µCi 14C-cabozantinib. The mean recovery of total radioactivity was 81.09%, with radioactivity eliminated in feces (53.79%) and urine (27.29%). Total radioactivity eliminated primarily in feces has also been reported in mass balance studies of anticancer RTK inhibitors gefitinib and erlotinib (Mckillop et al., 2004; Ling et al., 2006). Sample collection in our study was extended to 48 days postdose to maximize total 14C-cabozantinib-related radioactivity recovery; however, ,1% of total mean radioactivity was ultimately recovered in feces and urine after day 28 postdose. The total recovery of ,90% of administered 14C-cabozantinib radioactive dose is consistent with reports for mass balance studies of other anticancer drugs with long plasma elimination t1/2 (Beumer et al., 2006).. In the present study, the mean ...
2-Amino-2-Deoxy-d-[1-13c]galactose hydrochloride/ACM478518546 can be provided in Alfa Chemistry. We are dedicated to provide our customers the best products and services.
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Suitable for liquid scintillation counting, gamma counting and chromatography applications. Choose from a variety of vial, cap and liner materials. Scintillation vial materials include glass, HDPE and PP. Vials are available with caps attached or caps packaged separately.. ...
Rabbit plasma albumin was labelled with I131, injected intravenously, and measurements were made of the radioactivity in plasma, urine, and feces over many days. In some experiments plasma radioactivity was fractionated into I131-albumin activity and that of labelled breakdown products. Curves of these radioactivities were compared with corresponding curves predicted by four mathematical models. Each model included a vascular and extravascular albumin compartment in transfer equilibrium, a radioactive breakdown products compartment, and an excretion compartment; but model A supposed I131-albumin catabolism to occur within the vascular system, model B within the extravascular compartment, model C within both, and model D within a separate compartment receiving albumin for catabolism from the plasma. The experimental data were reasonably well predicted by models A and C. However, model D, though data were insufficient for its complete validation, gave the best predictions and agrees with present ...
This resource is designed to provide strategies for dealing with some of the misconceptions that students have in the form of ready-to-use classroom resources.
The various confounding factors that can adversely affect the accuracy of carbon-14 dating methods are evident in many of the other radioisotope dating
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TY - JOUR. T1 - Detection of Adriamycin-DNA adducts by accelerator mass spectrometry at clinically relevant Adriamycin concentrations. AU - Coldwell, Kate E.. AU - Cutts, Suzanne M.. AU - Ognibene, Ted J.. AU - Henderson, Paul. AU - Phillips, Don R.. PY - 2008. Y1 - 2008. N2 - Limited sensitivity of existing assays has prevented investigation of whether Adriamycin-DNA adducts are involved in the anti-tumour potential of Adriamycin. Previous detection has achieved a sensitivity of a few Adriamycin-DNA adducts/104 bp DNA, but has required the use of supra-clinical drug concentrations. This work sought to measure Adriamycin-DNA adducts at sub-micromolar doses using accelerator mass spectrometry (AMS), a technique with origins in geochemistry for radiocarbon dating. We have used conditions previously validated (by less sensitive decay counting) to extract [14C]Adriamycin-DNA adducts from cells and adapted the methodology to AMS detection. Here we show the first direct evidence of Adriamycin-DNA ...
The search for fractionally charged particles (FCP) in Nature is ultimately motivated by the belief that the fundamental constituents of the atomic nucleus are quarks, which have charge in integral units of k of the electronic charge. The reported observation of fractional charge in niobium by a group at Stanford University in 1981 has motivated many new efforts to detect FCP in the past few years. The techniques of accelerator mass spectrometry (AMSh) ave been successfully applied to this problem at several laboratories. The method generally involves the use of electrostatic analysis systems to separate the FCP from integrally charged ions, since the mass of the FCP is not known a priori. A variety of materials have been searched in these experiments and the most sensitive limits are at concentration levels of less than 10^(-18) FCP per atom of host material. ...
The last 10-15 years have witnessed a massively increased interest in collecting rare, single malt whiskies, with auction prices ranging from a few hundred pounds to many thousands. Consequently, these products have become a target for fraudsters who are selling what appear to be genuine old, rare whiskies that are actually relatively modern products. While the distilling industry can apply a number of modern analytical techniques to determine whether or not a whisky comes from the claimed distillery, it cannot determine the distillation year with any great accuracy. However, it has long been recognised that radiocarbon (14C) measurements can be used to estimate the production year of wines and spirits produced during the last 60 years or so, where the spirit was produced from a single years plant growth. This has relied on comparing the 14C measurements on the spirit with the northern hemisphere bomb calibration curve, produced from 14C measurements made on atmospheric CO2 and single year tree ...
LIVERMORE Calif. -- DNA damage formed during carcinogenesis is just o...Paul Henderson of Livermores Biology and Biotechnology Research Progr...Karen Dingley of BBRP will present the use of AMS to detect carcinogen...Other presentations include using AMS to study new potential biomarker...Henderson will present an overview of AMS applications in biological r...,Livermore,research,in,accelerator,mass,spectrometry,highlighted,at,ACS,meeting,biological,biology news articles,biology news today,latest biology news,current biology news,biology newsletters
Service Centers Northeast National Ion Microprobe Facility (NENIMF) The Northeast National Ion Microprobe Facility (NENIMF) is an outgrowth of the Woods Hole Oceanographic Institution (WHOI) Regional Ion Microprobe Facililty. National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) The Woods Hole Oceanographic Institutions National Ocean Sciences Accelerator Mass Spectrometry Facility (NOSAMS) was…
adshelp[at]cfa.harvard.edu The ADS is operated by the Smithsonian Astrophysical Observatory under NASA Cooperative Agreement NNX16AC86A ...
old due to standard statistical deviation in the rate of decay and halflife of carbon 14. The radiocarbon dating method could supply useful information about the 2 V. R. Switsur, Radiocarbon Date Calibration using historically dated standard deviation) and the conversions into calibrated ages (which are based upon the Radiocarbon dating is the use of a naturally occurring isotope of carbon to determine e.g., 3000±30BP indicates a standard deviation of 30 radiocarbon years. Accurate reporting of a 14C date includes: Indication of age in radiocarbon years (rcy BP) or in calender years (cal BP). Indication of standard deviation of dating an older man and a younger man quotes Radiocarbon Dating Laboratory Friday, 8 November 2013 Quoted errors are 1 standard deviation due to counting statistics multiplied by an experimentally Enrichment of 14C and radiocarbon dating where a reproducibility of 0.025% (one standard deviation) has been attained.1 Here we describe experiments in This paper describes ...
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Scintillation fluids based on toluene or xylene will no longer be available except by special order. Principal investigators who are authorized to use radioactive materials or are applying for such use may petition the Executive Committee for a scintillation fluid exception. Petitions must be submitted in writing and clearly state why the use of a scintillation counting fluid with a flash point , 140o F is required for their scintillation counting needs ...
Positron emission tomography (PET), a nuclear imaging technology for in vivo quantification of blood flow, metabolism, and protein distribution, is an invaluable tool for developing novel personalized therapies for high morbidity and mortality brain disorders (Benton et al., 2007; Depression Guideline Panel, 1999; Michalak et al., 2008; Trivedi, 2003; Vogt et al., 1994).
The indoor 222Rn radionuclide was directly absorbed in typical 20 ml glass scintillation vials by passing −3 dm3of ambient air through 16 ml of water-immiscible non-volataile scintillation cocktail...
Jeffrey Collins is the author of this article in the Journal of Visualized Experiments: Automation of a Positron-emission Tomography (PET) Radiotracer Synthesis Protocol for Clinical Production
carbon isotope ratio: A measure of the proportion of the carbon-14 isotope to the carbon-12 isotope. Living material contains carbon-14 and carbon-12 in the same ...
Supplier pricing and chemical structure of high purity D-[1-13C;1-2H]mannose a stable Carbon-13 and deuterium (2H) labeled isotope from Omicron Biochemicals, Inc.
24 Dec 2014 Ive been told that radiocarbon dating is highly inaccurate , i am an atheist and this Answer questions with accurate, in-depth explanations, including . says carbon dating is just flat out wrong and bad and stupid is wrong. 24 Oct 2012 - 3 min - Uploaded by Mike ScarboroughSo carbon dating is not good at measuring C14? Radiometric dating is accurate When radiocarbon dating was developed, it revolutionised archaeology, because it enabled them to more confidently date the past, and to build a more accurate . another, and usually, there has been good agreement between the methods. We also need to calibrate how much carbon-14 it had to begin with. . OK, Ill admit its a pile of bullshit, however, if you cant date anything with physical The statement was that you cant use C-14 dating for accuracy of over z dating questions tekst Radiocarbon dating is a method for determining the age of an object containing organic In addition to permitting more accurate dating within archaeological ...
Design, synthesis and evaluation in an LPS rodent model of neuroinflammation of a novel 18F-labelled PET tracer targeting P2X7. . Biblioteca virtual para leer y descargar libros, documentos, trabajos y tesis universitarias en PDF. Material universiario, documentación y tareas realizadas por universitarios en nuestra biblioteca. Para descargar gratis y para leer online.
In editor-in-chief Snellings THIRD paper (what an extensive community...), Snelling claims that his data are "deadly" to radiodating using carbon-14. It also gives some outright incorrect statements about carbon-14 -- or, at least, highly misleading. "[N]ot a single atom of 14C formed even 1 million years ago anywhere in or on the earth should conceivably still exist." Strictly speaking this is true -- although carbon-14 is generated in the troposphere all the time. Snelling references Whitelaws debunked article about radioactive decays as a centerpiece to his introduction. After an extensive discussion about how the fossils he is studying cannot be "truly that old," he gives an estimate of "36,400±350 to 48,710±930 years old" for the fossils, but then later concludes that they "are consistent with their burial during the Genesis Flood only, about 4,300 years ago." Huh? ...
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Define radioactivity: the property possessed by some elements (such as uranium) or isotopes (such as carbon 14) of spontaneously emitting energetic…
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Forwarded message ---------- From: Peter Douglas ,peter.douglas at mcgill.ca, Date: Thu, Oct 26, 2017 at 8:29 AM I am looking to recruit an M.Sc. or Ph.D. student in the Earth and Planetary Sciences Department at McGill University for a project focused on using methane radiocarbon measurements to quantify fugitive emissions from oil and gas extraction and/or emissions of methane from old permafrost carbon pools. This position would be partially focused on developing methods at McGill for purifying methane from mixed gas samples, and would involve collaborations with the University of Ottawas Lalonde Accelerator Mass Spectrometry Laboratory, as well as Environment and Climate Change Canada. The project is funded through McGills Trottier Institute for Science and Public Policy, and there will be opportunities to engage with the interface between biogeochemical measurements and greenhouse gas mitigation policy. Experience with stable isotope and/or radiocarbon measurements, especially with gas ...
Kinetic modeling using a reference region is a common method for the analysis of dynamic PET studies. Available methods for outlining regions of interest representing reference regions are usually time-consuming and difficult and tend to be subjective; therefore, MRI is used to help physicians and experts to define regions of interest with higher precision. The current work introduces a fast and automated method to delineate the reference region of images obtained from an N-methyl-(11)C-2-(4-methylaminophenyl)-6-hydroxy-benzothiazole ((11)C-PIB) PET study on Alzheimer disease patients and healthy controls using a newly introduced masked volumewise principal-component analysis.. METHODS: The analysis was performed on PET studies from 22 Alzheimer disease patients (baseline, follow-up, and test/retest studies) and 4 healthy controls, that is, a total of 26 individual scans. The second principal-component images, which illustrate the kinetic behavior of the tracer in gray matter of the cerebellar ...
RATIONALE: Imaging procedures, such as carbon-11 acetate positron emission tomography (PET) and fludeoxyglucose F 18 PET, may improve the ability to det
Turbidite systems along the continental margin of Cascadia Basin from Vancouver Island, Canada, to Cape Mendocino, California, United States, have been investigated with swath bathymetry; newly collected and archive piston, gravity, kasten, and box cores; and accelerator mass spectrometry radiocarbon dates. The purpose of this study is to test the applicability of the Holocene turbidite record as a paleoseismic record for the Cascadia subduction zone. The Cascadia Basin is an ideal place to develop a turbidite paleoseismologic method and to record paleoearthquakes because (1) a single subduction-zone fault underlies the Cascadia submarine-canyon systems; (2) multiple tributary canyons and a variety of turbidite systems and sedimentary sources exist to use in tests of synchronous turbidite triggering; (3) the Cascadia trench is completely sediment filled, allowing channel systems to trend seaward across the abyssal plain, rather than merging in the trench; (4) the continental shelf is wide, ...
Turbidite systems along the continental margin of Cascadia Basin from Vancouver Island, Canada, to Cape Mendocino, California, United States, have been investigated with swath bathymetry; newly collected and archive piston, gravity, kasten, and box cores; and accelerator mass spectrometry radiocarbon dates. The purpose of this study is to test the applicability of the Holocene turbidite record as a paleoseismic record for the Cascadia subduction zone. The Cascadia Basin is an ideal place to develop a turbidite paleoseismologic method and to record paleoearthquakes because (1) a single subduction-zone fault underlies the Cascadia submarine-canyon systems; (2) multiple tributary canyons and a variety of turbidite systems and sedimentary sources exist to use in tests of synchronous turbidite triggering; (3) the Cascadia trench is completely sediment filled, allowing channel systems to trend seaward across the abyssal plain, rather than merging in the trench; (4) the continental shelf is wide, ...
Some of these radioisotopes are tritium, carbon-14 and phosphorus-32. Certain light (low atomic number) primordial nuclides ( ... Here is a list of radioisotopes formed by the action of cosmic rays; the list also contains the production mode of the isotope ...
Some of these radioisotopes are tritium, carbon-14 and phosphorus-32. Here is a list of radioisotopes formed by the action of ... of nitrogen-14 forms carbon-14. This radioisotope can be released from the nuclear fuel cycle; this is the radioisotope ... In addition some natural radioisotopes are present. A recent paper reports the levels of long-lived radioisotopes in the ... Just because a radioisotope lands on the surface of the soil, does not mean it will enter the human food chain. After release ...
For example, one might culture plants in an environment in which the carbon dioxide contained radioactive carbon; then the ... Radioisotopes are also a method of treatment in hemopoietic forms of tumors; the success for treatment of solid tumors has been ... In nuclear medicine, radioisotopes are used for diagnosis, treatment, and research. Radioactive chemical tracers emitting gamma ... "Radioisotopes in Industry". World Nuclear Association. Martin, James (2006). Physics for Radiation Protection: A Handbook. p. ...
used in radioisotope thermoelectric generators (RTGs) and radioisotope heater units as an energy source for spacecraft ... For example, one might culture plants in an environment in which the carbon dioxide contained radioactive carbon; then the ... "Radioisotopes in Industry". World Nuclear Association.. *. Martin, James (2006). Physics for Radiation Protection: A Handbook. ... most commonly used medical radioisotope, used as a radioactive tracer Iodine-129 53. 76. 15,700,000 y. β−. 194 Cosmogenic. ...
Labeled with the radioisotope carbon-11, it can be used for positron emission tomography. Bengt Andree; et al. (August 1998). " ...
Some of the well-known naturally-occurring radioisotopes are tritium, carbon-14 and phosphorus-32. The timing of their ... carbon (carbon-14), chlorine, iodine and neon are formed within solar system materials through cosmic ray spallation, and are ...
Labeled with the radioisotope carbon-11, it can be used for positron emission tomography. Zheng LT, Hwang J, Ock J, Lee MG, Lee ...
The suggested power source would be an Advanced Stirling Radioisotope Generator (ASRG). After separation, the probe would be ... determine the noble gas abundances and isotopic ratios of hydrogen, carbon, nitrogen, oxygen, and argon in Saturn's atmosphere ... carbon, nitrogen, and oxygen. The probe would enter the atmosphere under a parachute and begin measurements at 0.1 bar (a bar ...
Radioisotopes of hydrogen, carbon, phosphorus, sulphur, and iodine have been used extensively to trace the path of biochemical ... 99mTc is a very versatile radioisotope, and is the most commonly used radioisotope tracer in medicine. It is easy to produce in ... The commonly used radioisotopes have short half lives and so do not occur in nature. They are produced by nuclear reactions. ... Instead it is made by neutron irradiation of the isotope 13C which occurs naturally in carbon at about the 1.1% level. 14C has ...
Cosmic rays may also produce radioisotopes on Earth (for example, carbon-14), which in turn decay and produce ionizing ... Measurements of carbon-14, can be used to date the remains of long-dead organisms (such as wood that is thousands of years old ... As humans, plants, and animals consume food, air, and water, an inventory of radioisotopes builds up within the organism (see ... Radioisotope Methodology Liebel F, Kaur S, Ruvolo E, Kollias N, Southall MD (2012). "Irradiation of skin with visible light ...
Other labels can be used, such as affinity, photochemical or radioisotope tags. These labels are attached to the probe itself ... Therefore, a number of label free detection methods are available, such as surface plasmon resonance (SPR), carbon nanotubes, ... carbon nanowire sensors (where detection occurs via changes in conductance) and microelectromechanical system (MEMS) ...
Additionally, Carbon-11 can also be made using a cyclotron; boron in the form of boric oxide is reacted with protons in a (p,n ... ³H, Tritium, the radioisotope of hydrogen, is available at very high specific activities, and compounds with this isotope in ... 14C, Carbon-14 can be made (as above), and it is possible to convert the target material into simple inorganic and organic ... 11C, Carbon-11 is usually produced by cyclotron bombardment of 14N with protons. The resulting nuclear reaction is 14N(p,α)11C ...
The X-10 reactor at Oak Ridge was used to produce radioisotopes such as cobalt-60, phosphorus-32, sulfur-35, and carbon-14. As ... A History of Radioisotopes in Science and Medicine (University of Chicago Press, 2013) on the use of radioisotopes in science ... Natural radioisotopes were used as tracers to track atoms and illuminate biological processes in living creatures and ... Bud, Robert (August 2015). "Angela N. H. Creager, Life Atomic: A History of Radioisotopes in Science and Medicine". Social ...
Radioisotopes can be transformed directly through changes in valence state by acting as acceptors or by acting as cofactors to ... In these particular cases, a carbon source such as ethanol is added to the medium to promote the reduction of nitrate at first ... The radioisotope interact with binding sites of metabolically active cells and is used as terminal electron acceptor in the ... Several radioisotopes of strontium, for example, are recognized as analogs of calcium and incorporated within Micrococcus ...
The most common radioisotopes for medical imaging agents, carbon-11 and fluorine-18, have a half-lives of 20.4 and 109.8 ... He has contributed major advances on the entire spectrum of research from fundamental chemistry methodology with radioisotopes ... Hooker and Stephen Buchwald (MIT) developed a strategy for labeling molecules with carbon-11 using cyanide nearly ... valproic acid and 4-phenylbutyric acid measured with carbon-11 labeled analogs by PET". Nuclear Medicine and Biology. 40 (7): ...
Labeled with the radioisotope carbon-11 it is used as a radioligand in positron emission tomography (PET) studies to determine ... WAY-100,635 may be labeled in different ways with carbon-11: As [carbonyl-11C]WAY-100,635 or [O-methyl-11C]WAY-100,635, with [ ...
This includes research on the biogeochemical cycles of the element carbon and on the record of climate change contained in ... including oceanic mixing based on stable and radioisotope distribution. ... However, his contributions stretch far beyond the "conveyor"; his work is the foundation of carbon cycle science, and his ... linking the circulation of the global ocean and made major contributions to the science of the carbon cycle and the use of ...
Carbon-14, the radioisotope of carbon-12, is naturally developed in trace amounts in the atmosphere and it can be detected in ... The radioisotope carbon-14 is constantly formed from nitrogen-14 (14N) in the higher atmosphere by incoming cosmic rays which ... Carbon of all types is continually used to form the molecules of the cells of organisms. Doubling of the concentration of 14C ... The radioisotope 14C thus becomes part of the biosphere so that all living organisms contain a certain amount of 14C. Nuclear ...
Radioisotopes with half-lives shorter than one million years are also produced: for example, carbon-14 by cosmic ray production ... Short-lived radioisotopes that are found in nature are continuously generated or replenished by natural processes, such as ... Uranium-236 is produced in uranium ores by neutrons from other radioisotopes. Iodine-129 is produced from tellurium-130 by ...
When tagged with the radioisotope carbon-11, martinostat can be used to quantify HDAC in the brain and peripheral organs using ...
... such as carbon-14, via the reaction: n + 14N → p + 14C. Cosmic rays kept the level of carbon-14[81] in the atmosphere roughly ... Mainly from radioisotopes in food (40K, 14C, etc.) (b)depends on diet. ... Carbon and oxygen nuclei collide with interstellar matter to form lithium, beryllium and boron in a process termed cosmic ray ... Reaction products of primary cosmic rays, radioisotope half-lifetime, and production reaction.[82]. *Tritium (12.3 years): 14N( ...
The melting of the Snowball Earth is associated with greenhouse warming due to the accumulation of high levels of carbon ... which could be dated through radioisotopes. Glacial deposits in South Australia are approximately the same age (about 630 Ma), ... Pierrehumbert, R.T. (2004). "High levels of atmospheric carbon dioxide necessary for the termination of global glaciation". ... "Global Glaciation Snowballed Into Giant Change in Carbon Cycle". ScienceDaily. 2010-05-02. Retrieved 2011-06-18. ...
Longer-life radioisotopes, typically caesium-137 and strontium-90, present a long-term hazard. Intense beta radiation from the ... The neutron irradiation of the atmosphere itself produces a small amount of activation, mainly as long-lived carbon-14 and ... The bomb casing can be a significant sources of neutron-activated radioisotopes. The neutron flux in the bombs, especially ... The primary fallout hazard is gamma radiation from short-lived radioisotopes, which represent the bulk of activity. Within 24 ...
Decreased uptake of the inhaled radioisotope may indicate an impaired ability to breathe, airway obstruction, or possible ... This has been performed with Gallium-68 labelled carbon nanoparticles (Galligas) using a conventional Technegas machine for ... specifically carbon nanoparticles containing technetium-99m. The perfusion phase of the test involves the intravenous injection ...
Usually radioisotope thermal generators use Pu 238 as a heat source because it has the lowest shielding requirements. ... First, normal moderator materials (carbon, water) add bulk and mass which is not desirable in a spacecraft. Second, for reasons ...
Radionuclides used in PET scanning are typically isotopes with short half-lives[3] such as carbon-11 (~20 min), nitrogen-13 (~ ... As the radioisotope undergoes positron emission decay (also known as positive beta decay), it emits a positron, an antiparticle ... BROWNELL G.L., Dave Marcum, B. HOOP JR., and D.E. BOHNING, "Quantitative dynamic studies using short-lived radioisotopes and ... Due to the short half-lives of most positron-emitting radioisotopes, the radiotracers have traditionally been produced using a ...
This project is supported by the Canadian Institutes of Health Research (award #111062), Alberta Innovates - Health Solutions, and by The Metabolomics Innovation Centre (TMIC), a nationally-funded research and core facility that supports a wide range of cutting-edge metabolomic studies. TMIC is funded by Genome Alberta, Genome British Columbia, and Genome Canada, a not-for-profit organization that is leading Canadas national genomics strategy with funding from the federal government. Maintenance, support, and commercial licensing is provided by OMx Personal Health Analytics, Inc. Designed by Educe Design & Innovation Inc. ...
Radioisotopes in archaeological dating- carbon-14 production of carbon- 14 (c-14) the most common isotope of carbon is c-12. ... Radiocarbon dating relies on the carbon isotopes carbon-14 and carbon-12. Radioactive isotope, also called radioisotope, ... Carbon-14, the radioactive isotope of carbon used in carbon dating has a half-life of 5730 years, so it decays too fast. Join ... Dating a fossil - carbon dating compares the ratio of carbon-12 to carbon-14 atoms in an organism. Join for free and see your ...
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They have the same ratio of carbon-14 to carbon-12 as the atmosphere, and this same ratio is then carried up the food chain all ... Most carbon on Earth exists as the very stable isotope carbon-12, with a very small amount as carbon-13. ... Uses of radioisotopes in carbon 14 dating Nelspruit women who is online now for dirty video chat. Posted by / 10-Feb-2017 09:30 ... They have the same ratio of carbon-14 to carbon-12 as the atmosphere, and this same ratio is then carried up the food chain all ...
A C3 plant absorbs a carbon radio isotope (aspartof14CO2). In which stable organic compound does the labeled ca.... BIOLOGY: ... Chromium is obtained by heating chromium(III) oxide with carbon. Calculate the mass percent of chromium in the .... Chemistry ...
B Production of molecular sideband radioisotope beams at CERN-ISOLDE using a Helicon-type plasma ion source (to be published ... 43 PARTICLE ACCELERATORS; BREEDING; CARBON; CARBON DIOXIDE; CARBON MONOXIDE; CHARGE STATES; ECR ION SOURCES; ELECTRON CYCLOTRON ... carbon beams in the frame of the ENSAR and EMILIE projects. Carbon is to date the lightest condensable element charge bred with ... Title: Future carbon beams at SPIRAL1 facility: Which method is the most efficient? ...
Isotopic Tracers; Radioisotopes. Stable and radioactive isotopes such as oxygen, hydrogen, carbon, nitrogen and sulfur have ... Biogeochemistry of Soils: Carbon/Water/Rock Interaction in the Critical Zone. show details View Publications. Carbon Cycling ... Biogeochemistry of Carbon and Nitrogen in Aquatic Environments. show details View Publications. Carbon Cycling and ... Carbon Fluxes in Geologic and Hydrologic Processes. show details View Publications. Biogeochemistry; Carbon Cycling and ...
AC3 plant absorbs a carbon radioisotope (as part of 14CO2). In which compound does the labeled carbon appear fi.... Biology: ...
We have compared the structural formulae of various trichothecenes and suggest that the presence of substituents on carbon-15 ... Carbon Radioisotopes. *Cyclic/biosynthesis/pharmacology. *Cycloheximide/pharmacology. *Dactinomycin/pharmacology. *Ethers. * ...
BETA DECAY RADIOISOTOPES; BETA-MINUS DECAY RADIOISOTOPES; CARBON 14 DECAY RADIOISOTOPES; DAYS LIVING RADIOISOTOPES; ECOLOGICAL ... NANOSEC LIVING RADIOISOTOPES; NEON 24 DECAY RADIOISOTOPES; NUCLEI; POLONIUM ISOTOPES; POPULATIONS; RADIOISOTOPES; RADIUM ... HEAVY ION DECAY RADIOISOTOPES; HEAVY NUCLEI; ISOMERIC TRANSITION ISOTOPES; ISOTOPES; LEAD ISOTOPES; MASS TRANSFER; MINERAL ... YEARS LIVING RADIOISOTOPES; 655003* - Medical Physics- Dosimetry; 540330 - Environment, Aquatic- Radioactive Materials ...
Carbon Nanotubes Give Two Excitons for the Price of One Efficient generation of photon pairs from modified carbon nanotubes ... Modular Fluidic System Developed to Supply Radioisotope Used in Targeted Alpha Therapy Laboratory automation applied to complex ... Reducing Friction with an Onion-Like Carbon Material Researchers developed a new self-generating lubricant with great potential ... New method can make films of atomically thin carbon that are over a foot long. ...
How is radioisotope dating different than relative dating of fossils, how does radiometric dating work?. This time, of the ...
What Is an Isotope? Radioisotopes Physics People Oxygen Nuclear Physics News Medicine Industry Geology Forensics carbon ... The ratio of carbon isotopes in three common species of tuna has changed substantially since 2000, suggesting major shifts are ... The ratio of carbon isotopes in three common species of tuna has changed substantially since 2000, suggesting major shifts are ...
A new real-time radioisotope imaging system (RRIS) to study the kinetics of nutrient uptake and transfer of photosynthetic ... 14C is a common radioisotope of carbon and useful to trace the photosynthetic products as well as a low energy beta emitter. ... Autoradiography Photosynthetic products Plant biology Carbon-14 Sulfur-35 Noninvasive measurement This is a preview of ... A new real-time radioisotope imaging system (RRIS) to study the kinetics of nutrient uptake and transfer of photosynthetic ...
Radionuclides also termed as radioisotopes are elements that possess radioactivity. It means upon decay they emit radiations ... Carbon dating. Radioactive carbon-14 decay could be used to estimate the age of organic materials. For example carbon dating ... Urinalysis; Bioassay; Tracer; Carbon dating. Introduction. Radioisotopes are widely used for a number of purposes following are ... Goh, KM (1991) Carbon dating. Carbon Isotope Techniques 1: 125.. *Dalrymple GB, Lanphere MA (1969) Potassium-argon dating: ...
Protector Work Stations with Built-In Blower use carbon-based filter cells to rid the work area of ha ... Activated Carbon Radioisotope SDS. Safety Data Sheet for Activated Carbon Filters used in Paramount Ductless Enclosures, ... Carbon Filter Capacity Application Note. This application note discusses the factors affecting the life of a carbon filter and ... Acid Impregnated Carbon Filter SDS. Safety Data Sheet for the Acid Impregnated Carbon Filters used in FilterMate Portable ...
FilterMate Portable Exhausters and Fume Adsorbers use carbon-based filters to rid the work area of ... Activated Carbon Radioisotope SDS. Safety Data Sheet for Activated Carbon Filters used in Paramount Ductless Enclosures, ... Two types of carbon or one type of carbon and a HEPA filter may be stacked for mixed use applications in these ductless hoods. ... These DH2 ductless hoods use stackable carbon filters to remove certain gases, solvents or radioisotopes. HEPA filters can be ...
Radioisotope definition, a radioactive isotope, usually artificially produced: used in physical and biological research, ... radioisotope. in Science. radioisotope. [rā′dē-ō-ī′sə-tōp′]. *A radioactive isotope of a chemical element. Carbon 14 and radon ... radioisotope. in Medicine. radioisotope. (rā′dē-ō-ī′sə-tōp′). n.. *A naturally or artificially produced radioactive isotope. ...
... solvents or radioisotopes. HEPA filters can be added to trap particulates. ... DH2 carbon filtered hoods that filter certain gases, ... Activated Carbon Radioisotope SDS. Safety Data Sheet for ... These DH2 ductless hoods use stackable carbon filters to remove certain gases, solvents or radioisotopes. HEPA filters can be ... Acid Impregnated Carbon Filter SDS. Safety Data Sheet for the Acid Impregnated Carbon Filters used in FilterMate Portable ...
Activated Carbon Radioisotope SDS. Safety Data Sheet for Activated Carbon Filters used in Paramount Ductless Enclosures, ... Acid Impregnated Carbon Filter SDS. Safety Data Sheet for the Acid Impregnated Carbon Filters used in FilterMate Portable ... Ammonia Impregnated Carbon Filter SDS. Safety Data Sheet for the Ammonia Impregnated Carbon Filters used in FilterMate Portable ... Formaldehyde Impregnated Carbon Filter SDS. Safety Data Sheet for the Formaldehyde Impregnated Carbon Filters used in ...
Carbon Radioisotopes. Fatty Acids / biosynthesis. Fatty Acids, Nonesterified / biosynthesis. Female. Glycerol / metabolism. ... 0/Carbon Radioisotopes; 0/Fatty Acids; 0/Fatty Acids, Nonesterified; 0/Lipids; 0/Lipoproteins; 0/Palmitates; 0/Triglycerides; ...
Carbon Radioisotopes * Heterocyclic Compounds * Mutagens * Quinolines * 2-amino-3-methylimidazo(4,5-f)quinoline ...
Carbon Radioisotopes. Chromatography, Thin Layer. Gossypium / metabolism*. Hydrolysis. Kinetics. Membrane Lipids / metabolism. ... 0/Carbon Radioisotopes; 0/Membrane Lipids; 0/Palmitic Acids; 0/Phosphatidylethanolamines; 0/Phospholipids; 57-10-3/Palmitic ...
  • At age thirty-six he became the youngest full professor at Chicago, where he carried out the work resulting in his winning the 1960 Nobel Prize in Chemistry "for his method to use carbon-14 for age determination in archaeology, geology, geophysics, and other branches of science. (encyclopedia.com)
  • He has contributed major advances on the entire spectrum of research from fundamental chemistry methodology with radioisotopes to human neuroimaging. (wikipedia.org)
  • Titan is unique in having an abundant, complex, and diverse carbon-rich chemistry on the surface of a water-ice-dominated world with an interior water ocean, making it a high-priority target for astrobiology and origin of life studies. (wikipedia.org)
  • Titan is a compelling astrobiology target because its surface contains abundant complex carbon-rich chemistry and because both liquid water and liquid hydrocarbons can occur on its surface, possibly forming a prebiotic primordial soup. (wikipedia.org)
  • Craig studied geology and chemistry at the University of Chicago, where he earned a Ph.D. under Nobel Laureate Harold Urey with a thesis on carbon isotope geochemistry in 1951. (wikipedia.org)
  • The rover could have been the first mission since the Viking program landers of the 1970s to specifically look for the chemistry associated with life (biosignatures), such as carbon-based compounds along with molecules involving both sulfur and nitrogen. (wikipedia.org)
  • The advantages compared to ferrite or elemental nanoparticles are: Higher magnetization Higher stability in acidic and basic solution as well as organic solvents Chemistry on the graphene surface via methods already known for carbon nanotubes Several methods exist for preparing magnetic nanoparticle. (wikipedia.org)
  • The overall objective of this project is to determine the role of chemical processes associated with dissolved organic carbon (DOC) on the transport and reactivity of both naturally occurring and anthropogenic compounds. (usgs.gov)
  • We have compared the structural formulae of various trichothecenes and suggest that the presence of substituents on carbon-15 of the common trichothecene ring may be important in determining the precise modes of action of this group of compounds. (mendeley.com)
  • The advantages of radioiodination, still the most versatile radiolabeling strategy, and other labeled compounds comprising covalently attached radioisotopes are compared to the use of chelator-protein conjugates that are complexed with metallic radioisotopes. (mdpi.com)
  • Carbon forms a vast number of compounds, more than any other element, with almost ten million compounds described to date, and yet that number is but a fraction of the number of theoretically possible compounds under standard conditions. (wikipedia.org)
  • Carbon is known to form almost ten million different compounds, a large majority of all chemical compounds. (wikipedia.org)
  • Carbon compounds form the basis of all known life on Earth, and the carbon-nitrogen cycle provides some of the energy produced by the Sun and other stars. (wikipedia.org)
  • Although it forms an extraordinary variety of compounds, most forms of carbon are comparatively unreactive under normal conditions. (wikipedia.org)
  • other compounds may be formed as well, e.g. carbon tetrafluoride, hexafluoropropylene, and highly toxic perfluoroisobutene (PFIB). (wikipedia.org)
  • Carbon-14 is also commonly used as a beta source in research, it is commonly used as a radiotracer in organic compounds. (wikipedia.org)
  • The resulting compound is known to absorb water and carbon dioxide, and may be used to remove vapors of these compounds from closed atmospheres. (wikipedia.org)
  • Before the technology of fluorescent labeling, radioisotopes were used to detect and identify molecular compounds. (wikipedia.org)
  • One of the most complex biochemical processes in God's creation is the ability plants possess to take in carbon dioxide and water and, with the. (icr.org)
  • The Keeling Curve, a record of atmospheric carbon dioxide levels initiated in 1958 by Charles David Keeling of the Scripps Institution of Oceanography at the University of California, San Diego, with samples taken at the National Oceanic and Atmospheric Administration's Mauna Loa Observatory in Hilo, Hawaii. (wikipedia.org)
  • In soils, technetium-99 (99Tc), carbon-14, strontium-90, cobalt-60 (60Co), iodine-129 (129I), iodine-131 (131I), americium-241 (241Am), neptunium-237 (237Np) and various forms of radioactive plutonium and uranium are the most common radionuclides. (wikipedia.org)
  • A radiotherapy machine may have roughly 1000 Ci of a radioisotope such as caesium-137 or cobalt-60. (wikipedia.org)
  • There the cobalt would be activated by the neutron flux in the reactor and become cobalt-60, a radioisotope with a five year half life that releases very energetic gamma rays. (wikipedia.org)
  • Because organisms stop taking in carbon-14 at death, the age of the material can be precisely determined by this ratio of carbon isotopes. (best-adult-dating-services.com)
  • The ratio of carbon isotopes in three common species of tuna has changed substantially since 2000, suggesting major shifts are taking place in phytoplankton populations that form the base of the ocean's food web, a new international study finds. (isoflex.com)
  • Ventilation imaging can also be performed using a Technegas machine which produces an aerosol of radioactive nanoparticles, specifically carbon nanoparticles containing technetium-99m. (wikipedia.org)
  • Engineered radioactive nanoparticles are used in medical imaging techniques such as positron emission tomography and single-photon emission computed tomography, and an aerosol of carbon nanoparticles containing technetium-99m are used in a commercially available procedure for ventilation/perfusion scintigraphy of the lungs. (wikipedia.org)
  • Technetium-99m, indium-111, and iodine-131 are common radioisotopes used for these purposes, with many others used as well. (wikipedia.org)
  • Radioisotope is used for biological labelling of cells or entities for identification or tracing specific molecules in an organism. (omicsonline.org)
  • B Production of molecular sideband radioisotope beams at CERN-ISOLDE using a Helicon-type plasma ion source (to be published)]: despite its refractory nature, radioactive carbon beams can be produced from molecules (CO or CO{sub 2}), which can subsequently be broken up and multi-ionized to the required charge state in charge breeders or ECR sources. (osti.gov)
  • At the moment of death, no new carbon-14 containing molecules are metabolized, therefore the ratio is at a maximum. (kentchemistry.com)
  • Hooker and Stephen Buchwald (MIT) developed a strategy for labeling molecules with carbon-11 using cyanide nearly instantaneously using a biaryl phosphine Pd(0) complexes. (wikipedia.org)
  • Carbon of all types is continually used to form the molecules of the cells of organisms. (wikipedia.org)
  • The present study investigated the spatial and vertical distribution of organic carbon (OC), total nitrogen (TN), total phosphorus (TP) and biogenic silica (BSi) in the sedimentary environments of Asia's largest brackish water lagoon. (springer.com)
  • Publishing in PNAS , They took 29 samples of hippos teeth, elephant tusks, and hair, that were collected on known dates between 1905 and 2008 in East Africa, and measured the levels of carbon-14 using accelerator mass spectrometry. (thenakedscientists.com)
  • However, the levels reported were consistent with levels expected from contamination and other extraneous sources, which are impossible to eliminate even when extraordinary care is taken in handling the samples, and chronologists disregard levels of carbon-14 below 0.5% of modern levels. (wikipedia.org)
  • Therefore, the overarching goal of this work is to measure the contribution of terrestrial-derived organic carbon and deuterium on nearshore heterotrophic production, and to trace the distinct isotopic signatures associated with glacier-derived organic matter through the marine food web. (usgs.gov)
  • Sources of terrestrial organic carbon in the Mississippi River plume region: Evidence for the importance of coastal marsh inputs. (tulane.edu)
  • 14 C is a common radioisotope of carbon and useful to trace the photosynthetic products as well as a low energy beta emitter. (springer.com)
  • This is also the only carbon radioisotope found in nature-trace quantities are formed cosmogenically by the reaction 14N + 1n → 14C + 1H. (wikipedia.org)
  • Generally speaking, trace radioisotopes have half-lives that are short in comparison with the age of the Earth, since primordial nuclides tend to occur in larger than trace amounts. (wikipedia.org)
  • Trace radioisotopes are therefore present only because they are continually produced on Earth by natural processes. (wikipedia.org)
  • John Marmion Edmond FRS (April 27, 1943 - April 10, 2001) was a professor of marine geochemistry and oceanography at the Massachusetts Institute of Technology, who did pioneering work on oceanic particulate matter, the oceanic carbon dioxide cycle, trace elements, and radioisotopes. (wikipedia.org)
  • For example, carbon isotope ratios are measured relative to the international standard for C. The C standard is produced from a fossil belemnite found in the Peedee Formation, which is a limestone formed in the Cretaceous period in South Carolina, U.S.A. The fossil is referred to as VPDB (Vienna Pee Dee Belemnite) and has 13C:12C ratio of 0.0112372. (wikipedia.org)
  • From 1976 until it ceased operation with Weinberg's retirement in 1984, the Institute for Energy Analysis was a center for study of diverse issues related to carbon dioxide and global climate. (wikipedia.org)
  • The rate of carbon release from permafrost soils is highly uncertain, but it is crucial for predicting the strength and timing of this carbon-cycle feedback effect, and thus how important permafrost thaw will be for climate change this century and beyond. (nih.gov)
  • 90Sr, 2 Bq dm−3 137Cs, 5 Bq dm−3 239Pu, 0.001 Bq dm−3 241Am, 0.001 Bq dm−3 Jiří Hála's textbook states that soils vary greatly in their ability to bind radioisotopes, the clay particles and humic acids can alter the distribution of the isotopes between the soil water and the soil. (wikipedia.org)
  • In particular, I am interested in the mechanisms controlling carbon storage in soils and how plants and soil microbes interact in the nitrogen cycle. (bangor.ac.uk)
  • How is radioisotope dating different than relative dating of fossils, what are some carbon sequestration methods? (iphone5cashback.info)
  • Examples include impact and control of invasive Asian carp, Lyme disease vector ecology, Illinois water supply quality and quantity investigations, geologic carbon sequestration, development of geospatial tools, discovery and excavation of massive prehistoric settlements surrounding Cahokia in advance of new bridge construction, persistence of estrogens in dairy farm wastewater, electronics re-use to minimize electronic waste, and monitoring atmospheric deposition of radioisotopes in North America following the Fukushima reactor incident. (wikipedia.org)
  • Carbon sequestration in clay mineral fractions from 14C-labeled plant residues. (wikipedia.org)
  • The basic approach is to label a candidate drug using the radioisotope carbon-14,[citation needed] and then administer the compound to human volunteers at levels typically about 100 times lower than the proposed therapeutic dosage (from around 1 to 100 micrograms but not above). (wikipedia.org)
  • This has been performed with Gallium-68 labelled carbon nanoparticles (Galligas) using a conventional Technegas machine for ventilation images, and with Gallium-68 labelled MAA (Ga68-MAA) for perfusion images. (wikipedia.org)
  • Animal studies on some classes of nanoparticles indicate pulmonary effects including inflammation, granulomas, and pulmonary fibrosis, which were of similar or greater potency when compared with other known fibrogenic materials such as silica, asbestos, and ultrafine carbon black. (wikipedia.org)
  • In particular, cerebral D2 receptor binding as measured by carbon-11-raclopride (11C-raclopride) has shown to reflect disease severity of Huntington's disease, a genetical disease characterized by selective degeneration of cerebral D2 receptors. (wikipedia.org)
  • Paper discusses the testing conducted on the Paramount Ductless Enclosure that shows carbon filter effectiveness and fume and particulate containment of particulates. (labconco.com)
  • Thin film carbon foils are used to strip electrons to produce this short lived, critical. (globalspec.com)
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