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.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.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 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.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.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.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.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.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.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)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.Radiometric Dating: Techniques used to determine the age of materials, based on the content and half-lives of the RADIOACTIVE ISOTOPES they contain.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.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.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.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.Isotopes: Atomic species differing in mass number but having the same atomic number. (Grant & Hackh's Chemical Dictionary, 5th ed)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.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.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.Methods: A series of steps taken in order to conduct research.Radiometry: 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.TritiumNostoc 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.Whole-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.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.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.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.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)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.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.Absorption: The physical or physiological processes by which substances, tissue, cells, etc. take up or take in other substances or energy.Antibodies, Monoclonal: Antibodies produced by a single clone of cells.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.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.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.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.Half-Life: The time it takes for a substance (drug, radioactive nuclide, or other) to lose half of its pharmacologic, physiologic, or radiologic activity.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.Tomography, Emission-Computed: Tomography using radioactive emissions from injected RADIONUCLIDES and computer ALGORITHMS to reconstruct an image.Time Factors: Elements of limited time intervals, contributing to particular results or situations.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)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.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.Bone Neoplasms: Tumors or cancer located in bone tissue or specific BONES.Mass Spectrometry: An analytical method used in determining the identity of a chemical based on its mass using mass analyzers/mass spectrometers.Kinetics: The rate dynamics in chemical or physical systems.Radiotherapy Dosage: The total amount of radiation absorbed by tissues as a result of radiotherapy.Transplantation, Heterologous: Transplantation between animals of different species.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.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.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.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.Feces: Excrement from the INTESTINES, containing unabsorbed solids, waste products, secretions, and BACTERIA of the DIGESTIVE SYSTEM.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.Erythrocytes: Red blood cells. Mature erythrocytes are non-nucleated, biconcave disks containing HEMOGLOBIN whose function is to transport OXYGEN.Liver: A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.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.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.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.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.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.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.Feasibility Studies: Studies to determine the advantages or disadvantages, practicability, or capability of accomplishing a projected plan, study, or project.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.Kidney: Body organ that filters blood for the secretion of URINE and that regulates ion concentrations.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.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.Chromatography, High Pressure Liquid: Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.Lung: Either of the pair of organs occupying the cavity of the thorax that effect the aeration of the blood.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.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.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.Sodium: A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.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)Tomography, X-Ray Computed: Tomography using x-ray transmission and a computer algorithm to reconstruct the image.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 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.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.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.Breast Neoplasms: Tumors or cancer of the human BREAST.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).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.Cell Line, Tumor: A cell line derived from cultured tumor cells.Treatment Outcome: Evaluation undertaken to assess the results or consequences of management and procedures used in combating disease in order to determine the efficacy, effectiveness, safety, and practicability of these interventions in individual cases or series.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.Cell Line: Established cell cultures that have the potential to propagate indefinitely.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.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.