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)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.TritiumTissue 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.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.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)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.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)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.Liver: A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.Chromatography, Thin Layer: Chromatography on thin layers of adsorbents rather than in columns. The adsorbent can be alumina, silica gel, silicates, charcoals, or cellulose. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Radiometry: The measurement of radiation by photography, as in x-ray film and film badge, by Geiger-Mueller tube, and by SCINTILLATION COUNTING.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)Kinetics: The rate dynamics in chemical or physical systems.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.Chromatography, High Pressure Liquid: Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.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.Bile: An emulsifying agent produced in the LIVER and secreted into the DUODENUM. Its composition includes BILE ACIDS AND SALTS; CHOLESTEROL; and ELECTROLYTES. It aids DIGESTION of fats in the duodenum.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)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.Biotransformation: The chemical alteration of an exogenous substance by or in a biological system. The alteration may inactivate the compound or it may result in the production of an active metabolite of an inactive parent compound. The alterations may be divided into METABOLIC DETOXICATION, PHASE I and METABOLIC DETOXICATION, PHASE II.Chromatography, Paper: An analytical technique for resolution of a chemical mixture into its component compounds. Compounds are separated on an adsorbent paper (stationary phase) by their varied degree of solubility/mobility in the eluting solvent (mobile phase).Half-Life: The time it takes for a substance (drug, radioactive nuclide, or other) to lose half of its pharmacologic, physiologic, or radiologic activity.Feces: Excrement from the INTESTINES, containing unabsorbed solids, waste products, secretions, and BACTERIA of the DIGESTIVE SYSTEM.Radioactive Tracers: Radioactive substances added in minute amounts to the reacting elements or compounds in a chemical process and traced through the process by appropriate detection methods, e.g., Geiger counter. Compounds containing tracers are often said to be tagged or labeled. (Hawley's Condensed Chemical Dictionary, 12th ed)Scintillation Counting: Detection and counting of scintillations produced in a fluorescent material by ionizing radiation.Rats, Inbred Strains: Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations or by parent x offspring matings carried out with certain restrictions. This also includes animals with a long history of closed colony breeding.Water Pollution, RadioactiveTomography, Emission-Computed: Tomography using radioactive emissions from injected RADIONUCLIDES and computer ALGORITHMS to reconstruct an image.Fluorine Radioisotopes: Unstable isotopes of fluorine that decay or disintegrate emitting radiation. F atoms with atomic weights 17, 18, and 20-22 are radioactive fluorine isotopes.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.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.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Leucine: An essential branched-chain amino acid important for hemoglobin formation.Injections, Intravenous: Injections made into a vein for therapeutic or experimental purposes.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.Trichloroacetic Acid: A strong acid used as a protein precipitant in clinical chemistry and also as a caustic for removing warts.Palmitic Acids: A group of 16-carbon fatty acids that contain no double bonds.Oxyquinoline: An antiseptic with mild fungistatic, bacteriostatic, anthelmintic, and amebicidal action. It is also used as a reagent and metal chelator, as a carrier for radio-indium for diagnostic purposes, and its halogenated derivatives are used in addition as topical anti-infective agents and oral antiamebics.Radioimmunodetection: Use of radiolabeled antibodies for diagnostic imaging of neoplasms. Antitumor antibodies are labeled with diverse radionuclides including iodine-131, iodine-123, indium-111, or technetium-99m and injected into the patient. Images are obtained by a scintillation camera.Iodine Isotopes: Stable iodine atoms that have the same atomic number as the element iodine, but differ in atomic weight. I-127 is the only naturally occurring stable iodine isotope.Chromatography: Techniques used to separate mixtures of substances based on differences in the relative affinities of the substances for mobile and stationary phases. A mobile phase (fluid or gas) passes through a column containing a stationary phase of porous solid or liquid coated on a solid support. Usage is both analytical for small amounts and preparative for bulk amounts.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.Whole-Body Counting: Measurement of radioactivity in the entire human body.Rhenium: Rhenium. A metal, atomic number 75, atomic weight 186.2, symbol Re. (Dorland, 28th ed)Indium: A metallic element, atomic number 49, atomic weight 114.82, symbol In. It is named from its blue line in the spectrum. (From Dorland, 28th 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).Sulfur Isotopes: Stable sulfur atoms that have the same atomic number as the element sulfur, but differ in atomic weight. S-33, 34, and 36 are stable sulfur isotopes.Radiochemistry: The study of the chemical and physical phenomena of radioactive substances.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.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.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.Methods: A series of steps taken in order to conduct research.Administration, Oral: The giving of drugs, chemicals, or other substances by mouth.Phospholipids: Lipids containing one or more phosphate groups, particularly those derived from either glycerol (phosphoglycerides see GLYCEROPHOSPHOLIPIDS) or sphingosine (SPHINGOLIPIDS). They are polar lipids that are of great importance for the structure and function of cell membranes and are the most abundant of membrane lipids, although not stored in large amounts in the system.GlucosamineElectrophoresis, Polyacrylamide Gel: Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.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).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.Centrifugation, Density Gradient: Separation of particles according to density by employing a gradient of varying densities. At equilibrium each particle settles in the gradient at a point equal to its density. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Organotechnetium Compounds: Organic compounds that contain technetium as an integral part of the molecule. These compounds are often used as radionuclide imaging agents.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.Intestinal Absorption: Uptake of substances through the lining of the INTESTINES.Amino Acids: Organic compounds that generally contain an amino (-NH2) and a carboxyl (-COOH) group. Twenty alpha-amino acids are the subunits which are polymerized to form proteins.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)Water Pollutants, Radioactive: Pollutants, present in water or bodies of water, which exhibit radioactivity.Sulfur Radioisotopes: Unstable isotopes of sulfur that decay or disintegrate spontaneously emitting radiation. S 29-31, 35, 37, and 38 are radioactive sulfur isotopes.Brain: The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.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.Molecular Weight: The sum of the weight of all the atoms in a molecule.Lutetium: Lutetium. An element of the rare earth family of metals. It has the atomic symbol Lu, atomic number 71, and atomic weight 175.Methionine: A sulfur-containing essential L-amino acid that is important in many body functions.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.Affinity Labels: Analogs of those substrates or compounds which bind naturally at the active sites of proteins, enzymes, antibodies, steroids, or physiological receptors. These analogs form a stable covalent bond at the binding site, thereby acting as inhibitors of the proteins or steroids.Polonium: Polonium. A radioactive element that is a member of the chalcogen family. It has the atomic symbol Po, atomic number 84, and the atomic weight of the isotope with the longest half-life (209Po) is 208.98. It decays by alpha-emission.Subcellular Fractions: Components of a cell produced by various separation techniques which, though they disrupt the delicate anatomy of a cell, preserve the structure and physiology of its functioning constituents for biochemical and ultrastructural analysis. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p163)Chromatography, Gel: Chromatography on non-ionic gels without regard to the mechanism of solute discrimination.Kidney: Body organ that filters blood for the secretion of URINE and that regulates ion concentrations.Sulfates: Inorganic salts of sulfuric acid.Absorption: The physical or physiological processes by which substances, tissue, cells, etc. take up or take in other substances or energy.Soil Pollutants, Radioactive: Pollutants, present in soil, which exhibit radioactivity.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.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.Phosphatidylinositols: Derivatives of phosphatidic acids in which the phosphoric acid is bound in ester linkage to the hexahydroxy alcohol, myo-inositol. Complete hydrolysis yields 1 mole of glycerol, phosphoric acid, myo-inositol, and 2 moles of fatty acids.Spectrometry, Gamma: Determination of the energy distribution of gamma rays emitted by nuclei. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Phosphatidylethanolamines: Derivatives of phosphatidic acids in which the phosphoric acid is bound in ester linkage to an ethanolamine moiety. Complete hydrolysis yields 1 mole of glycerol, phosphoric acid and ethanolamine and 2 moles of fatty acids.UridineMicrosomes: Artifactual vesicles formed from the endoplasmic reticulum when cells are disrupted. They are isolated by differential centrifugation and are composed of three structural features: rough vesicles, smooth vesicles, and ribosomes. Numerous enzyme activities are associated with the microsomal fraction. (Glick, Glossary of Biochemistry and Molecular Biology, 1990; from Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)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.Metrizamide: A solute for density gradient centrifugation offering higher maximum solution density without the problems of increased viscosity. It is also used as a resorbable, non-ionic contrast medium.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.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.Phosphates: Inorganic salts of phosphoric acid.Iodobenzoates: Benzoic acid esters or salts substituted with one or more iodine atoms.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)Air Pollutants, Radioactive: Pollutants, present in air, which exhibit radioactivity.Phosphatidylcholines: Derivatives of phosphatidic acids in which the phosphoric acid is bound in ester linkage to a choline moiety. Complete hydrolysis yields 1 mole of glycerol, phosphoric acid and choline and 2 moles of fatty acids.Choline: A basic constituent of lecithin that is found in many plants and animal organs. It is important as a precursor of acetylcholine, as a methyl donor in various metabolic processes, and in lipid metabolism.Technetium Tc 99m Aggregated Albumin: A gamma-emitting radionuclide imaging agent used for the diagnosis of diseases in many tissues, particularly in cardiovascular and cerebral circulation.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.Cell Fractionation: Techniques to partition various components of the cell into SUBCELLULAR FRACTIONS.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)Arabinofuranosyluracil: A pyrimidine nucleoside formed in the body by the deamination of CYTARABINE.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.Idoxuridine: An analog of DEOXYURIDINE that inhibits viral DNA synthesis. The drug is used as an antiviral agent.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.Carbon Dioxide: A colorless, odorless gas that can be formed by the body and is necessary for the respiration cycle of plants and animals.Perfusion: Treatment process involving the injection of fluid into an organ or tissue.Inositol: An isomer of glucose that has traditionally been considered to be a B vitamin although it has an uncertain status as a vitamin and a deficiency syndrome has not been identified in man. (From Martindale, The Extra Pharmacopoeia, 30th ed, p1379) Inositol phospholipids are important in signal transduction.Glucuronides: Glycosides of GLUCURONIC ACID formed by the reaction of URIDINE DIPHOSPHATE GLUCURONIC ACID with certain endogenous and exogenous substances. Their formation is important for the detoxification of drugs, steroid excretion and BILIRUBIN metabolism to a more water-soluble compound that can be eliminated in the URINE and BILE.Technetium Compounds: Inorganic compounds that contain TECHNETIUM as an integral part of the molecule. Technetium 99m (m=metastable) is an isotope of technetium that has a half-life of about 6 hours. Technetium 99, which has a half-life of 210,000 years, is a decay product of technetium 99m.Dogs: The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)Glutamates: Derivatives of GLUTAMIC ACID. Included under this heading are a broad variety of acid forms, salts, esters, and amides that contain the 2-aminopentanedioic acid structure.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.Glucuronates: Derivatives of GLUCURONIC ACID. Included under this heading are a broad variety of acid forms, salts, esters, and amides that include the 6-carboxy glucose structure.Radioactive Fallout: The material that descends to the earth or water well beyond the site of a surface or subsurface nuclear explosion. (McGraw-Hill Dictionary of Chemical and Technical Terms, 4th ed)Mass Spectrometry: An analytical method used in determining the identity of a chemical based on its mass using mass analyzers/mass spectrometers.Gamma Cameras: Electronic instruments that produce photographs or cathode-ray tube images of the gamma-ray emissions from organs containing radionuclide tracers.Chromatography, Ion Exchange: Separation technique in which the stationary phase consists of ion exchange resins. The resins contain loosely held small ions that easily exchange places with other small ions of like charge present in solutions washed over the resins.ThymidineMicrosomes, Liver: Closed vesicles of fragmented endoplasmic reticulum created when liver cells or tissue are disrupted by homogenization. They may be smooth or rough.FucoseBackground Radiation: Radiation from sources other than the source of interest. It is due to cosmic rays and natural radioactivity in the environment.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.Electrophoresis: An electrochemical process in which macromolecules or colloidal particles with a net electric charge migrate in a solution under the influence of an electric current.Hydrolysis: The process of cleaving a chemical compound by the addition of a molecule of water.Chromatography, Gas: Fractionation of a vaporized sample as a consequence of partition between a mobile gaseous phase and a stationary phase held in a column. Two types are gas-solid chromatography, where the fixed phase is a solid, and gas-liquid, in which the stationary phase is a nonvolatile liquid supported on an inert solid matrix.Chemistry: A basic science concerned with the composition, structure, and properties of matter; and the reactions that occur between substances and the associated energy exchange.Cell Membrane: The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.Chemical Phenomena: The composition, conformation, and properties of atoms and molecules, and their reaction and interaction processes.Glycerides: GLYCEROL esterified with FATTY ACIDS.EstersArea Under Curve: A statistical means of summarizing information from a series of measurements on one individual. It is frequently used in clinical pharmacology where the AUC from serum levels can be interpreted as the total uptake of whatever has been administered. As a plot of the concentration of a drug against time, after a single dose of medicine, producing a standard shape curve, it is a means of comparing the bioavailability of the same drug made by different companies. (From Winslade, Dictionary of Clinical Research, 1992)Whole Body Imaging: The creation of a visual display of the inside of the entire body of a human or animal for the purposes of diagnostic evaluation. This is most commonly achieved by using MAGNETIC RESONANCE IMAGING; or POSITRON EMISSION TOMOGRAPHY.Azides: Organic or inorganic compounds that contain the -N3 group.Benperidol: A butyrophenone with general properties similar to those of HALOPERIDOL. It has been used in the treatment of aberrant sexual behavior. (From Martindale, The Extra Pharmacopoeia, 30th ed, p567)Body Burden: The total amount of a chemical, metal or radioactive substance present at any time after absorption in the body of man or animal.Tyramine: An indirect sympathomimetic. Tyramine does not directly activate adrenergic receptors, but it can serve as a substrate for adrenergic uptake systems and monoamine oxidase so it prolongs the actions of adrenergic transmitters. It also provokes transmitter release from adrenergic terminals. Tyramine may be a neurotransmitter in some invertebrate nervous systems.Mevalonic AcidFood Contamination, RadioactiveHexosaminesHeterocyclic 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.Dihydroxyphenylalanine: A beta-hydroxylated derivative of phenylalanine. The D-form of dihydroxyphenylalanine has less physiologic activity than the L-form and is commonly used experimentally to determine whether the pharmacological effects of LEVODOPA are stereospecific.Cells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.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.Protein Biosynthesis: The biosynthesis of PEPTIDES and PROTEINS on RIBOSOMES, directed by MESSENGER RNA, via TRANSFER RNA that is charged with standard proteinogenic AMINO ACIDS.Glycoproteins: Conjugated protein-carbohydrate compounds including mucins, mucoid, and amyloid glycoproteins.Biological Availability: The extent to which the active ingredient of a drug dosage form becomes available at the site of drug action or in a biological medium believed to reflect accessibility to a site of action.PyruvatesMacaca fascicularis: A species of the genus MACACA which typically lives near the coast in tidal creeks and mangrove swamps primarily on the islands of the Malay peninsula.Uracil NucleotidesMannose: A hexose or fermentable monosaccharide and isomer of glucose from manna, the ash Fraxinus ornus and related plants. (From Grant & Hackh's Chemical Dictionary, 5th ed & Random House Unabridged Dictionary, 2d ed)Erythrocytes: Red blood cells. Mature erythrocytes are non-nucleated, biconcave disks containing HEMOGLOBIN whose function is to transport OXYGEN.Borohydrides: A class of inorganic or organic compounds that contain the borohydride (BH4-) anion.Adenine: A purine base and a fundamental unit of ADENINE NUCLEOTIDES.Acylation: The addition of an organic acid radical into a molecule.Proteins: Linear POLYPEPTIDES that are synthesized on RIBOSOMES and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of AMINO ACIDS determines the shape the polypeptide will take, during PROTEIN FOLDING, and the function of the protein.Antibodies, Monoclonal: Antibodies produced by a single clone of cells.Chemical Precipitation: The formation of a solid in a solution as a result of a chemical reaction or the aggregation of soluble substances into complexes large enough to fall out of solution.Cattle: Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.Cholesterol: The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils.Oleic Acids: A group of fatty acids that contain 18 carbon atoms and a double bond at the omega 9 carbon.Serum Albumin: A major protein in the BLOOD. It is important in maintaining the colloidal osmotic pressure and transporting large organic molecules.Centrifugation: Process of using a rotating machine to generate centrifugal force to separate substances of different densities, remove moisture, or simulate gravitational effects. It employs a large motor-driven apparatus with a long arm, at the end of which human and animal subjects, biological specimens, or equipment can be revolved and rotated at various speeds to study gravitational effects. (From Websters, 10th ed; McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Organ Specificity: Characteristic restricted to a particular organ of the body, such as a cell type, metabolic response or expression of a particular protein or antigen.Protein Binding: The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.Lipid Metabolism: Physiological processes in biosynthesis (anabolism) and degradation (catabolism) of LIPIDS.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.Cell Line: Established cell cultures that have the potential to propagate indefinitely.Air Pollution, RadioactiveModels, Biological: Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.Lung: Either of the pair of organs occupying the cavity of the thorax that effect the aeration of the blood.Guinea Pigs: A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.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.Dolichol: Eicosamethyl octacontanonadecasen-1-o1. Polyprenol found in animal tissues that contains about 20 isoprene residues, the one carrying the alcohol group being saturated.Microscopy, Electron: Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.Radiation ProtectionMetabolism: The chemical reactions that occur within the cells, tissues, or an organism. These processes include both the biosynthesis (ANABOLISM) and the breakdown (CATABOLISM) of organic materials utilized by the living organism.Stearic Acids: A group of compounds that are derivatives of octadecanoic acid which is one of the most abundant fatty acids found in animal lipids. (Stedman, 25th ed)Ribose: A pentose active in biological systems usually in its D-form.Ethanolamine: A viscous, hygroscopic amino alcohol with an ammoniacal odor. It is widely distributed in biological tissue and is a component of lecithin. It is used as a surfactant, fluorimetric reagent, and to remove CO2 and H2S from natural gas and other gases.Radiation Monitoring: The observation, either continuously or at intervals, of the levels of radiation in a given area, generally for the purpose of assuring that they have not exceeded prescribed amounts or, in case of radiation already present in the area, assuring that the levels have returned to those meeting acceptable safety standards.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.Germanium: A rare metal element with a blue-gray appearance and atomic symbol Ge, atomic number 32, and atomic weight 72.63.Blood Proteins: Proteins that are present in blood serum, including SERUM ALBUMIN; BLOOD COAGULATION FACTORS; and many other types of proteins.Caproates: Derivatives of caproic acid. Included under this heading are a broad variety of acid forms, salts, esters, and amides that contain a carboxy terminated six carbon aliphatic structure.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).Galactose: An aldohexose that occurs naturally in the D-form in lactose, cerebrosides, gangliosides, and mucoproteins. Deficiency of galactosyl-1-phosphate uridyltransferase (GALACTOSE-1-PHOSPHATE URIDYL-TRANSFERASE DEFICIENCY DISEASE) causes an error in galactose metabolism called GALACTOSEMIA, resulting in elevations of galactose in the blood.Trypsin: A serine endopeptidase that is formed from TRYPSINOGEN in the pancreas. It is converted into its active form by ENTEROPEPTIDASE in the small intestine. It catalyzes hydrolysis of the carboxyl group of either arginine or lysine. EC 220.127.116.11.Orotic AcidLevulinic Acids: Keto acids that are derivatives of 4-oxopentanoic acids (levulinic acid).Chylomicrons: A class of lipoproteins that carry dietary CHOLESTEROL and TRIGLYCERIDES from the SMALL INTESTINE to the tissues. Their density (0.93-1.006 g/ml) is the same as that of VERY-LOW-DENSITY LIPOPROTEINS.Neoplasms, Experimental: Experimentally induced new abnormal growth of TISSUES in animals to provide models for studying human neoplasms.Blood Platelets: Non-nucleated disk-shaped cells formed in the megakaryocyte and found in the blood of all mammals. They are mainly involved in blood coagulation.Avidin: A specific protein in egg albumin that interacts with BIOTIN to render it unavailable to mammals, thereby producing biotin deficiency.Radioactive Hazard Release: Uncontrolled release of radioactive material from its containment. This either threatens to, or does, cause exposure to a radioactive hazard. Such an incident may occur accidentally or deliberately.Lysosomes: A class of morphologically heterogeneous cytoplasmic particles in animal and plant tissues characterized by their content of hydrolytic enzymes and the structure-linked latency of these enzymes. The intracellular functions of lysosomes depend on their lytic potential. The single unit membrane of the lysosome acts as a barrier between the enzymes enclosed in the lysosome and the external substrate. The activity of the enzymes contained in lysosomes is limited or nil unless the vesicle in which they are enclosed is ruptured. Such rupture is supposed to be under metabolic (hormonal) control. (From Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)Chernobyl Nuclear Accident: April 25th -26th, 1986 nuclear power accident that occurred at Chernobyl in the former USSR (Ukraine) located 80 miles north of Kiev.Tin: A trace element that is required in bone formation. It has the atomic symbol Sn, atomic number 50, and atomic weight 118.71.Relative Biological Effectiveness: The ratio of radiation dosages required to produce identical change based on a formula comparing other types of radiation with that of gamma or roentgen rays.Hydroxylamines: Organic compounds that contain the (-NH2OH) radical.