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.
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)
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.
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)
Unstable isotopes of strontium that decay or disintegrate spontaneously emitting radiation. Sr 80-83, 85, and 89-95 are radioactive strontium isotopes.
The process in certain BACTERIA; FUNGI; and CYANOBACTERIA converting free atmospheric NITROGEN to biologically usable forms of nitrogen, such as AMMONIA; NITRATES; and amino compounds.
Unstable isotopes of iodine that decay or disintegrate emitting radiation. I atoms with atomic weights 117-139, except I 127, are radioactive iodine isotopes.
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.
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.
Unstable isotopes of sodium that decay or disintegrate emitting radiation. Na atoms with atomic weights 20-22 and 24-26 are radioactive sodium isotopes.
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)
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.
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.
Stable nitrogen atoms that have the same atomic number as the element nitrogen, but differ in atomic weight. N-15 is a stable nitrogen isotope.
Unstable isotopes of yttrium that decay or disintegrate emitting radiation. Y atoms with atomic weights 82-88 and 90-96 are radioactive yttrium isotopes.
Inorganic compounds that contain nitrogen as an integral part of the molecule.
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.
Unstable isotopes of carbon that decay or disintegrate emitting radiation. C atoms with atomic weights 10, 11, and 14-16 are radioactive carbon isotopes.
The circulation of nitrogen in nature, consisting of a cycle of biochemical reactions in which atmospheric nitrogen is compounded, dissolved in rain, and deposited in the soil, where it is assimilated and metabolized by bacteria and plants, eventually returning to the atmosphere by bacterial decomposition of organic matter.
The urea concentration of the blood stated in terms of nitrogen content. Serum (plasma) urea nitrogen is approximately 12% higher than blood urea nitrogen concentration because of the greater protein content of red blood cells. Increases in blood or serum urea nitrogen are referred to as azotemia and may have prerenal, renal, or postrenal causes. (From Saunders Dictionary & Encyclopedia of Laboratory Medicine and Technology, 1984)
Nitrogen oxide (NO2). A highly poisonous gas. Exposure produces inflammation of lungs that may only cause slight pain or pass unnoticed, but resulting edema several days later may cause death. (From Merck, 11th ed) It is a major atmospheric pollutant that is able to absorb UV light that does not reach the earth's surface.
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.
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.
Unstable isotopes of phosphorus that decay or disintegrate emitting radiation. P atoms with atomic weights 28-34 except 31 are radioactive phosphorus isotopes.
High energy POSITRONS or ELECTRONS ejected from a disintegrating atomic nucleus.
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.
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.
A gamma-emitting radionuclide imaging agent used for the diagnosis of diseases in many tissues, particularly in the gastrointestinal system, liver, and spleen.
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.
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.
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.
Nitrogenous products of NITRIC OXIDE synthases, ranging from NITRIC OXIDE to NITRATES. These reactive nitrogen intermediates also include the inorganic PEROXYNITROUS ACID and the organic S-NITROSOTHIOLS.
Hafnium. A metal element of atomic number 72 and atomic weight 178.49, symbol Hf. (From Dorland, 28th ed)
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.
Unstable isotopes of gold that decay or disintegrate emitting radiation. Au 185-196, 198-201, and 203 are radioactive gold isotopes.
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.
Any diagnostic evaluation using radioactive (unstable) isotopes. This diagnosis includes many nuclear medicine procedures as well as radioimmunoassay tests.
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.
Unstable isotopes of sulfur that decay or disintegrate spontaneously emitting radiation. S 29-31, 35, 37, and 38 are radioactive sulfur isotopes.
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. 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.
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. An element of the rare earth family of metals. It has the atomic symbol Lu, atomic number 71, and atomic weight 175.
Rhenium. A metal, atomic number 75, atomic weight 186.2, symbol Re. (Dorland, 28th ed)
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.
Inorganic oxides that contain nitrogen.
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)
Pollutants, present in soil, which exhibit radioactivity.
A family of signal transducing adaptor proteins that control the METABOLISM of NITROGEN. They are primarily found in prokaryotes.
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.
Detection and counting of scintillations produced in a fluorescent material by ionizing radiation.
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.
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.
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)
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)
Techniques used to determine the age of materials, based on the content and half-lives of the RADIOACTIVE ISOTOPES they contain.
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.
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.
Atomic species differing in mass number but having the same atomic number. (Grant & Hackh's Chemical Dictionary, 5th ed)
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.
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.
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.
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.
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.
Determination of the energy distribution of gamma rays emitted by nuclei. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
A colorless alkaline gas. It is formed in the body during decomposition of organic materials during a large number of metabolically important reactions. Note that the aqueous form of ammonia is referred to as AMMONIUM HYDROXIDE.
Inorganic or organic salts and esters of nitric acid. These compounds contain the NO3- radical.
An iron chelating agent with properties like EDETIC ACID. DTPA has also been used as a chelator for other metals, such as plutonium.
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.
Substances or mixtures that are added to the soil to supply nutrients or to make available nutrients already present in the soil, in order to increase plant growth and productivity.
A type of high-energy radiotherapy using a beam of gamma-radiation produced by a radioisotope source encapsulated within a teletherapy unit.
A series of steps taken in order to conduct research.
A specialty field of radiology concerned with diagnostic, therapeutic, and investigative use of radioactive compounds in a pharmaceutical form.
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.
A technetium imaging agent used in renal scintigraphy, computed tomography, lung ventilation imaging, gastrointestinal scintigraphy, and many other procedures which employ radionuclide imaging agents.
Tritium is an isotope of hydrogen (specifically, hydrogen-3) that contains one proton and two neutrons in its nucleus, making it radioactive with a half-life of about 12.3 years, and is used in various applications including nuclear research, illumination, and dating techniques due to its low energy beta decay.
The measurement of radiation by photography, as in x-ray film and film badge, by Geiger-Mueller tube, and by SCINTILLATION COUNTING.
Compounds that contain the triphenylmethane aniline structure found in rosaniline. Many of them have a characteristic magenta color and are used as COLORING AGENTS.
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.
Derivatives of ammonium compounds, NH4+ Y-, in which all four of the hydrogens bonded to nitrogen have been replaced with hydrocarbyl groups. These are distinguished from IMINES which are RN=CR2.
Measurement of radioactivity in the entire human body.
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.

Reciprocal ST-segment depression associated with exercise-induced ST-segment elevation indicates residual viability after myocardial infarction. (1/204)

OBJECTIVES: We evaluated the clinical significance of reciprocal ST-segment depression associated with exercise-induced ST-segment elevation for detecting residual viability within the infarcted area. BACKGROUND: Although the relation between residual viability and exercise-induced ST-segment elevation has been described, there are no reports focusing on the relation between myocardial viability and reciprocal ST-segment depression associated with exercise-induced ST-segment elevation. METHODS: We evaluated regional blood flow and glucose utilization using N-13 ammonia (NH3) and F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) in 30 patients with a previous Q-wave myocardial infarction (anterior in 15, inferior in 15). All subjects had single-vessel disease and had exercise-induced ST-segment elevations (> or =1 mm) in electrocardiographic leads. RESULTS: Reciprocal ST-segment depression (> or =1 mm) was present in 16 patients (Group A; anterior in 6, inferior in 10) but not in the remaining 14 patients (Group B). The degree of exercise-induced ST-segment elevation (1.8+/-0.2 vs. 2.0+/-0.2 mm) and the time from the onset of infarction to the study (75+/-49 vs. 74+/-52 days) did not differ between groups. There were no significant differences between groups in the severity of left ventricular dysfunction and the residual luminal narrowing in the infarct-related artery (45+/-21 vs. 48+/-25%). The presence and site of infarction were confirmed by NH3-PET in all patients. FDG-PET demonstrated residual tissue viability within infarct-related area in all patients in Group A and in 3 (21%) of 14 patients in Group B (p < 0.01). The sensitivity, specificity and accuracy of reciprocal ST-segment depression associated with exercise-induced ST-segment elevation for detecting residual viability were 84%, 100% and 90%, respectively. CONCLUSIONS: The occurrence of reciprocal ST-segment depression associated with exercise-induced ST segment elevation in patients with a previous Q-wave infarction who had single-vessel disease indicates residual tissue viability within the infarct-related area.  (+info)

13N-ammonia myocardial blood flow and uptake: relation to functional outcome of asynergic regions after revascularization. (2/204)

OBJECTIVES: In this study we determined whether 13N-ammonia uptake measured late after injection provides additional insight into myocardial viability beyond its value as a myocardial blood flow tracer. BACKGROUND: Myocardial accumulation of 13N-ammonia is dependent on both regional blood flow and metabolic trapping. METHODS: Twenty-six patients with chronic coronary artery disease and left ventricular dysfunction underwent prerevascularization 13N-ammonia and 18F-deoxyglucose (FDG) positron emission tomography, and thallium single-photon emission computed tomography. Pre- and postrevascularization wall-motion abnormalities were assessed using gated cardiac magnetic resonance imaging or gated radionuclide angiography. RESULTS: Wall motion improved in 61 of 107 (57%) initially asynergic regions and remained abnormal in 46 after revascularization. Mean absolute myocardial blood flow was significantly higher in regions that improved compared to regions that did not improve after revascularization (0.63+/-0.27 vs. 0.52+/-0.25 ml/min/g, p < 0.04). Similarly, the magnitude of late 13N-ammonia uptake and FDG uptake was significantly higher in regions that improved (90+/-20% and 94+/-25%, respectively) compared to regions that did not improve after revascularization (67+/-24% and 71+/-25%, p < 0.001 for both, respectively). However, late 13N-ammonia uptake was a significantly better predictor of functional improvement after revascularization (area under the receiver operating characteristic [ROC] curve = 0.79) when compared to absolute blood flow (area under the ROC curve = 0.63, p < 0.05). In addition, there was a linear relationship between late 13N-ammonia uptake and FDG uptake (r = 0.68, p < 0.001) as well as thallium uptake (r = 0.76, p < 0.001) in all asynergic regions. CONCLUSIONS: These data suggest that beyond its value as a perfusion tracer, late 13N-ammonia uptake provides useful information regarding functional recovery after revascularization. The parallel relationship among 13N-ammonia, FDG, and thallium uptake supports the concept that uptake of 13N-ammonia as measured from the late images may provide important insight regarding cell membrane integrity and myocardial viability.  (+info)

Exercise four hour redistribution thallium-201 single photon emission computed tomography and exercise induced ST segment elevation in detecting the viable myocardium in patients with acute myocardial infarction. (3/204)

OBJECTIVE: To investigate the specificity and sensitivity of the combination of redistribution in exercise thallium-201 single photon emission computed tomography (SPECT) and exercise induced ST elevation for detecting the viable myocardium in patients with acute myocardial infarction. DESIGN: 37 patients were studied within seven weeks of onset of Q wave myocardial infarction (anterior in 22, inferior in 15). All patients underwent exercise four hour redistribution thallium-201 SPECT and positron emission tomography using fluorine-18-fluorodeoxyglucose (FDG) and nitrogen-13 ammonia under fasting conditions. RESULTS: Sixteen patients showed exercise induced ST elevation >/= 1.5 mm, and 15 of these had increased FDG uptake in the infarct region. Eleven of 16 patients (10 of 11 patients with anterior infarctions) with irreversible thallium-201 defects and increased FDG uptake showed exercise induced ST elevation. The sensitivity, specificity, and predictive accuracy of redistribution, exercise induced ST segment elevation, or both for detecting increased FDG uptake were 82%, 75%, and 67% (94%, 75%, and 91% for anterior infarctions), respectively. CONCLUSIONS: In patients with acute Q wave myocardial infarction, the combination of redistribution in exercise thallium-201 SPECT and exercise induced ST elevation can detect the viable myocardium in the infarct region with high sensitivity and specificity, especially in patients with anterior infarctions.  (+info)

PET imaging of oxidative metabolism abnormalities in sympathetically denervated canine myocardium. (4/204)

This study was designed to test the hypothesis that regional sympathetic denervation produces perfusion and metabolic alterations in myocardial tissue under resting conditions. METHODS: PET studies of myocardial sympathetic innervation, myocardial perfusion and oxygen utilization using [11C]hydroxyephedrine (HED), [13N]ammonia and 1-[11C]acetate, respectively, were performed before and approximately 2 and 8 wk after surgical left thoracotomy and regional chemical sympathetic denervation (n = 5). A second group of animals underwent the same surgical procedure but, so that they could serve as a sham control group, were not sympathetically denervated (n = 5). The second group of animals was imaged before and 2 wk after surgery. Images of the retention of [11C]HED taken from 50 to 60 min postinjection were used to differentiate sympathetically innervated and denervated regions of the left ventricle. Regions of interest were defined on polar plots of the [11C]HED retention, including the sympathetically denervated territory and normally innervated regions. Regions defined on the HED polar plots were then transferred to the [13N]ammonia and 1-[11C]acetate image data, and tracer kinetic models were fit to the regional time-activity curves to generate estimates of myocardial perfusion and oxidative metabolism. RESULTS: The average percentage of the left ventricle denervated in the group I animals was 13.1% +/- 7.3%. Significant reductions in oxidative metabolism were observed in the sympathectomized tissue both at 2 and 8 wk after surgery (22% and 15% reductions, respectively). Significant alterations in regional perfusion were not observed. No significant changes in oxidative metabolism or perfusion were observed in the sham control group. CONCLUSION: Regional sympathetic denervation alters oxidative metabolism but not perfusion in the denervated region of the heart.  (+info)

Quantification of myocardial blood flow using 13N-ammonia and PET: comparison of tracer models. (5/204)

Several tracer kinetic methods have been proposed for quantification of regional myocardial blood flow (MBF) with 13N-ammonia and PET. Merits and limitations specific to each approach, however, generally are not clear, because they have not been evaluated in the same experimental environment. Therefore, we compared six different commonly used methods (11 modifications) to characterize the accuracy of each approach. The methods included the two-parameter model (method 1), the modified two-parameter model (method 2), the four-parameter model (method 3), the graphical analysis (method 4), the first-pass extraction method (method 5) and the dose uptake index (DUI; method 6). METHODS: Eleven studies in four dogs, 16 studies in eight healthy human volunteers and 14 studies in seven patients were performed using 13N-ammonia and PET. MBF in dogs was varied with dipyridamole and coronary occlusions and was measured independently and simultaneously with microspheres. Volunteers and patients were studied at baseline and after dipyridamole. MBF and DUI were estimated using a time-activity curve (Qi[t]) derived from dynamic images and regions of interest (ROls) and using the six methods. DUI was defined as Qi(t = 2 min) x weight/dose. RESULTS: MBF estimated by methods 1-5 correlated well with microsphere MBF in dogs. MBF estimates by method 1 correlated well with those by methods 2, 4 and 5 and to a lesser degree with those by method 3 in both dog and human studies. DUI correlated poorly with MBF by microspheres and by methods 1-5 in both dog and human studies. MBF estimates by method 3 showed larger dispersion (SD/mean flow) and higher sensitivity to metabolites correction in arterial blood than those by methods 1, 2, 4 and 5. CONCLUSION: MBF can be measured accurately using 13N-ammonia PET and tracer kinetic methods. DUI is a poor indicator of MBF values. The results indicate that preference should be given to the two-parameter model, incorporating geometrical ROI representation (method 2) among the compartment models, and to the graphical analysis (method 4) among the noncompartmental approaches.  (+info)

Use of molecular and isotopic techniques to monitor the response of autotrophic ammonia-oxidizing populations of the beta subdivision of the class proteobacteria in arable soils to nitrogen fertilizer. (6/204)

This study examined the effects of NH(4)NO(3) fertilizer on the size and activity of nitrifying, autotrophic, ammonia-oxidizing populations of the beta subdivision of the class Proteobacteria in arable soils. Plots under different long-term fertilizer regimes were sampled before and after NH(4)NO(3) additions, and the rates of nitrification were determined by (15)N isotopic pool dilution assays. Ammonia-oxidizing populations in the plots were quantified by competitive PCR assays based on the amoA and ribosomal 16S genes. Prior to fertilizer addition, ammonium concentrations and nitrification rates in the plots were comparatively low; ammonia-oxidizing populations were present at 10(4) to 10(5) gene copies g of soil(-1). Three days after the application of fertilizer, nitrification rates had risen considerably but the size of the ammonia-oxidizing population was unchanged. Six weeks after fertilizer treatment, ammonium concentrations and nitrification rates had fallen while the ammonia-oxidizing populations in plots receiving fertilizer had increased. The rapidity of the rise in nitrification rates observed after 3 days suggests that it results from phenotypic changes in the ammonia-oxidizing bacterial population. Associated increases in population sizes were only observed after 6 weeks and did not correlate directly with nitrifying activity. Phylogenetic analyses of PCR products from one of the plots revealed a population dominated by Nitrosospira-type organisms, similar to those prevalent in other soils.  (+info)

Effect of mental stress on myocardial blood flow and vasomotion in patients with coronary artery disease. (7/204)

In patients with coronary artery disease (CAD), mental stress may provoke ischemic electrocardiograph changes and abnormalities in regional and global left ventricular function. However, little is known about the underlying myocardial blood flow response (MBF) in these patients. METHODS: We investigated the hemodynamic, neurohumoral, and myocardial blood flow responses to mental stress in 17 patients with CAD and 17 healthy volunteers of similar age. Mental stress was induced by asking individuals to solve mathematic subtractions in a progressively challenging sequence; MBF was quantified at rest and during mental stress using 13N ammonia PET. RESULTS: Mental stress induced significant (P < 0.01) and comparable increases in rate-pressure product, measured in beats per minute x mm Hg, in both patients (from 7826 +/- 2006 to 10586 +/- 2800) and healthy volunteers (from 8227 +/- 1272 to 10618 +/- 2468). Comparable increases also occurred in serum epinephrine (58% in patients versus 52% in healthy volunteers) and norepinephrine (22% in patients versus 27% in healthy volunteers). Although MBF increased in patients (from 0.67 +/- 0.15 to 0.77 +/- 0.18 mL/min/g, P < 0.05) and healthy volunteers (from 0.73 +/- 0.13 to 0.95 +/- 0.22 mL/min/g, P < 0.001), the magnitude of flow increase was smaller in patients (14% +/- 17%) than in healthy volunteers (29% +/- 14%) (P = 0.01). The increase in MBF during mental stress correlated significantly with changes in cardiac work in healthy volunteers (r = 0.77; P < 0.001) but not in patients. CONCLUSION: Despite similar increases in cardiac work and comparable sympathetic stimulation in CAD patients and healthy volunteers, CAD patients exhibit an attenuated blood flow response to mental stress that may contribute to mental stress-induced ischemic episodes in daily life.  (+info)

Regulation of myocardial blood flow response to mental stress in healthy individuals. (8/204)

Mental stress testing has been proposed as a noninvasive tool to evaluate endothelium-dependent coronary vasomotion. In patients with coronary artery disease, mental stress can induce myocardial ischemia. However, even the determinants of the physiological myocardial blood flow (MBF) response to mental stress are poorly understood. Twenty-four individuals (12 males/12 females, mean age 49 +/- 13 yr, range 31-74 yr) with a low likelihood for coronary artery disease were studied. Serum catecholamines, cardiac work, and MBF (measured quantitatively with N-13 ammonia and positron emission tomography) were assessed. During mental stress (arithmetic calculation) MBF increased significantly from 0.70 +/- 0.14 to 0.92 +/- 0.21 ml x min(-1) x g(-1) (P < 0.01). Mental stress caused significant increases (P < 0.01) in serum epinephrine (26 +/- 16 vs. 42 +/- 17 pg/ml), norepinephrine (272 +/- 139 vs. 322 +/- 136 pg/ml), and cardiac work [rate-pressure product (RPP) 8,011 +/- 1,884 vs. 10,416 +/- 2,711]. Stress-induced changes in cardiac work were correlated with changes in MBF (r = 0.72; P < 0.01). Multiple-regression analysis revealed stress-induced changes in the RPP as the only significant (P = 0.0001) predictor for the magnitude of mental stress-induced increases in MBF in healthy individuals. Data from this group of healthy individuals should prove useful to investigate coronary vasomotion in individuals at risk for or with documented coronary artery disease.  (+info)

Nitrogen radioisotopes are unstable isotopes of the element nitrogen that emit radiation as they decay into more stable forms. Nitrogen has several radioisotopes, with the most common being nitrogen-13 and nitrogen-15. These isotopes have 7 protons in their nucleus, but differ in the number of neutrons.

Nitrogen-13 has a half-life of about 10 minutes, making it useful for medical imaging studies such as positron emission tomography (PET) scans. When nitrogen-13 decays, it emits a positron, which then collides with an electron and produces gamma rays that can be detected by a PET scanner.

Nitrogen-15, on the other hand, has a half-life of about 3 minutes and is not typically used for medical imaging. However, it is widely used in research settings as a stable isotope tracer to study metabolic processes in the body.

It's important to note that handling and using radioisotopes requires specialized training and equipment due to their potential radiation hazards.

Radioisotopes, also known as radioactive isotopes or radionuclides, are variants of chemical elements that have unstable nuclei and emit radiation in the form of alpha particles, beta particles, gamma rays, or conversion electrons. These isotopes are formed when an element's nucleus undergoes natural or artificial radioactive decay.

Radioisotopes can be produced through various processes, including nuclear fission, nuclear fusion, and particle bombardment in a cyclotron or other types of particle accelerators. They have a wide range of applications in medicine, industry, agriculture, research, and energy production. In the medical field, radioisotopes are used for diagnostic imaging, radiation therapy, and in the labeling of molecules for research purposes.

It is important to note that handling and using radioisotopes requires proper training, safety measures, and regulatory compliance due to their ionizing radiation properties, which can pose potential health risks if not handled correctly.

Zinc radioisotopes are unstable isotopes or variants of the element zinc that undergo radioactive decay, emitting radiation in the process. These isotopes have a different number of neutrons than the stable isotope of zinc (zinc-64), which contributes to their instability and tendency to decay.

Examples of zinc radioisotopes include zinc-65, zinc-70, and zinc-72. These isotopes are often used in medical research and diagnostic procedures due to their ability to emit gamma rays or positrons, which can be detected using specialized equipment.

Zinc radioisotopes may be used as tracers to study the metabolism and distribution of zinc in the body, or as therapeutic agents to deliver targeted radiation therapy to cancer cells. However, it is important to note that the use of radioisotopes carries potential risks, including exposure to ionizing radiation and the potential for damage to healthy tissues.

The Radioisotope Dilution Technique is a method used in nuclear medicine to measure the volume and flow rate of a particular fluid in the body. It involves introducing a known amount of a radioactive isotope, or radioisotope, into the fluid, such as blood. The isotope mixes with the fluid, and samples are then taken from the fluid at various time points.

By measuring the concentration of the radioisotope in each sample, it is possible to calculate the total volume of the fluid based on the amount of the isotope introduced and the dilution factor. The flow rate can also be calculated by measuring the concentration of the isotope over time and using the formula:

Flow rate = Volume/Time

This technique is commonly used in medical research and clinical settings to measure cardiac output, cerebral blood flow, and renal function, among other applications. It is a safe and reliable method that has been widely used for many years. However, it does require the use of radioactive materials and specialized equipment, so it should only be performed by trained medical professionals in appropriate facilities.

Strontium radioisotopes are radioactive isotopes of the element strontium. Strontium is an alkaline earth metal that is found in nature and has several isotopes, some of which are stable and some of which are radioactive. The radioactive isotopes of strontium, also known as strontium radionuclides, decay and emit radiation in the form of beta particles.

Strontium-89 (^89Sr) and strontium-90 (^90Sr) are two common radioisotopes of strontium that are used in medical applications. Strontium-89 is a pure beta emitter with a half-life of 50.5 days, which makes it useful for the treatment of bone pain associated with metastatic cancer. When administered, strontium-89 is taken up by bones and irradiates the bone tissue, reducing pain and improving quality of life in some patients.

Strontium-90, on the other hand, has a longer half-life of 28.8 years and emits more powerful beta particles than strontium-89. It is used as a component in radioactive waste and in some nuclear weapons, but it is not used in medical applications due to its long half-life and high radiation dose.

It's important to note that exposure to strontium radioisotopes can be harmful to human health, especially if ingested or inhaled. Therefore, handling and disposal of strontium radioisotopes require special precautions and regulations.

Nitrogen fixation is a process by which nitrogen gas (N2) in the air is converted into ammonia (NH3) or other chemically reactive forms, making it available to plants and other organisms for use as a nutrient. This process is essential for the nitrogen cycle and for the growth of many types of plants, as most plants cannot utilize nitrogen gas directly from the air.

In the medical field, nitrogen fixation is not a commonly used term. However, in the context of microbiology and infectious diseases, some bacteria are capable of fixing nitrogen and this ability can contribute to their pathogenicity. For example, certain species of bacteria that colonize the human body, such as those found in the gut or on the skin, may be able to fix nitrogen and use it for their own growth and survival. In some cases, these bacteria may also release fixed nitrogen into the environment, which can have implications for the ecology and health of the host and surrounding ecosystems.

Iodine radioisotopes are radioactive isotopes of the element iodine, which decays and emits radiation in the form of gamma rays. Some commonly used iodine radioisotopes include I-123, I-125, I-131. These radioisotopes have various medical applications such as in diagnostic imaging, therapy for thyroid disorders, and cancer treatment.

For example, I-131 is commonly used to treat hyperthyroidism and differentiated thyroid cancer due to its ability to destroy thyroid tissue. On the other hand, I-123 is often used in nuclear medicine scans of the thyroid gland because it emits gamma rays that can be detected by a gamma camera, allowing for detailed images of the gland's structure and function.

It is important to note that handling and administering radioisotopes require specialized training and safety precautions due to their radiation-emitting properties.

Krypton is a noble gas with the symbol Kr and atomic number 36. It exists in various radioisotopes, which are unstable isotopes of krypton that undergo radioactive decay. A few examples include:

1. Krypton-81: This radioisotope has a half-life of about 2.1 x 10^5 years and decays via electron capture to rubidium-81. It is produced naturally in the atmosphere by cosmic rays.
2. Krypton-83: With a half-life of approximately 85.7 days, this radioisotope decays via beta decay to bromine-83. It can be used in medical imaging for lung ventilation studies.
3. Krypton-85: This radioisotope has a half-life of about 10.7 years and decays via beta decay to rubidium-85. It is produced as a byproduct of nuclear fission and can be found in trace amounts in the atmosphere.
4. Krypton-87: With a half-life of approximately 76.3 minutes, this radioisotope decays via beta decay to rubidium-87. It is not found naturally on Earth but can be produced artificially.

It's important to note that while krypton radioisotopes have medical applications, they are also associated with potential health risks due to their radioactivity. Proper handling and safety precautions must be taken when working with these substances.

Indium radioisotopes refer to specific types of radioactive indium atoms, which are unstable and emit radiation as they decay. Indium is a chemical element with the symbol In and atomic number 49. Its radioisotopes are often used in medical imaging and therapy due to their unique properties.

For instance, one commonly used indium radioisotope is Indium-111 (^111In), which has a half-life of approximately 2.8 days. It emits gamma rays, making it useful for diagnostic imaging techniques such as single-photon emission computed tomography (SPECT). In clinical applications, indium-111 is often attached to specific molecules or antibodies that target particular cells or tissues in the body, allowing medical professionals to monitor biological processes and identify diseases like cancer.

Another example is Indium-113m (^113mIn), which has a half-life of about 99 minutes. It emits low-energy gamma rays and is used as a source for in vivo counting, typically in the form of indium chloride (InCl3) solution. This radioisotope can be used to measure blood flow, ventilation, and other physiological parameters.

It's important to note that handling and using radioisotopes require proper training and safety measures due to their ionizing radiation properties.

Sodium radioisotopes are unstable forms of sodium, an element naturally occurring in the human body, that emit radiation as they decay over time. These isotopes can be used for medical purposes such as imaging and treatment of various diseases. Commonly used sodium radioisotopes include Sodium-22 (^22Na) and Sodium-24 (^24Na).

It's important to note that the use of radioisotopes in medicine should be under the supervision of trained medical professionals, as improper handling or exposure can pose health risks.

Radioactivity is not typically considered within the realm of medical definitions, but since it does have medical applications and implications, here is a brief explanation:

Radioactivity is a natural property of certain elements (referred to as radioisotopes) that emit particles or electromagnetic waves due to changes in their atomic nuclei. This process can occur spontaneously without any external influence, leading to the emission of alpha particles, beta particles, gamma rays, or neutrons. These emissions can penetrate various materials and ionize atoms along their path, which can cause damage to living tissues.

In a medical context, radioactivity is used in both diagnostic and therapeutic settings:

1. Diagnostic applications include imaging techniques such as positron emission tomography (PET) scans and single-photon emission computed tomography (SPECT), where radioisotopes are introduced into the body to visualize organ function or detect diseases like cancer.
2. Therapeutic uses involve targeting radioisotopes directly at cancer cells, either through external beam radiation therapy or internal radiotherapy, such as brachytherapy, where a radioactive source is placed near or within the tumor.

While radioactivity has significant medical benefits, it also poses risks due to ionizing radiation exposure. Proper handling and safety measures are essential when working with radioactive materials to minimize potential harm.

Barium radioisotopes are radioactive forms of the element barium, which are used in medical imaging procedures to help diagnose various conditions. The radioisotopes emit gamma rays that can be detected by external devices, allowing doctors to visualize the inside of the body. Barium sulfate is often used as a contrast agent in X-rays and CT scans, but when combined with a radioisotope such as barium-133, barium-198, or barium-207, it can provide more detailed images of specific organs or systems.

For example, barium sulfate mixed with barium-133 may be used in a lung scan to help diagnose pulmonary embolism or other respiratory conditions. Barium-207 is sometimes used in bone scans to detect fractures, tumors, or infections.

It's important to note that the use of radioisotopes carries some risks, including exposure to radiation and potential allergic reactions to the barium compound. However, these risks are generally considered low compared to the benefits of accurate diagnosis and effective treatment.

Radionuclide imaging, also known as nuclear medicine, is a medical imaging technique that uses small amounts of radioactive material, called radionuclides or radiopharmaceuticals, to diagnose and treat various diseases and conditions. The radionuclides are introduced into the body through injection, inhalation, or ingestion and accumulate in specific organs or tissues. A special camera then detects the gamma rays emitted by these radionuclides and converts them into images that provide information about the structure and function of the organ or tissue being studied.

Radionuclide imaging can be used to evaluate a wide range of medical conditions, including heart disease, cancer, neurological disorders, gastrointestinal disorders, and bone diseases. The technique is non-invasive and generally safe, with minimal exposure to radiation. However, it should only be performed by qualified healthcare professionals in accordance with established guidelines and regulations.

Nitrogen isotopes are different forms of the nitrogen element (N), which have varying numbers of neutrons in their atomic nuclei. The most common nitrogen isotope is N-14, which contains 7 protons and 7 neutrons in its nucleus. However, there are also heavier stable isotopes such as N-15, which contains one extra neutron.

In medical terms, nitrogen isotopes can be used in research and diagnostic procedures to study various biological processes. For example, N-15 can be used in a technique called "nitrogen-15 nuclear magnetic resonance (NMR) spectroscopy" to investigate the metabolism of nitrogen-containing compounds in the body. Additionally, stable isotope labeling with nitrogen-15 has been used in clinical trials and research studies to track the fate of drugs and nutrients in the body.

In some cases, radioactive nitrogen isotopes such as N-13 or N-16 may also be used in medical imaging techniques like positron emission tomography (PET) scans to visualize and diagnose various diseases and conditions. However, these applications are less common than the use of stable nitrogen isotopes.

Yttrium radioisotopes are radioactive isotopes or variants of the element Yttrium, which is a rare earth metal. These radioisotopes are artificially produced and have unstable nuclei that emit radiation in the form of gamma rays or high-speed particles. Examples of yttrium radioisotopes include Yttrium-90 and Yttrium-86, which are used in medical applications such as radiotherapy for cancer treatment and molecular imaging for diagnostic purposes.

Yttrium-90 is a pure beta emitter with a half-life of 64.1 hours, making it useful for targeted radionuclide therapy. It can be used to treat liver tumors, leukemia, and lymphoma by attaching it to monoclonal antibodies or other targeting agents that selectively bind to cancer cells.

Yttrium-86 is a positron emitter with a half-life of 14.7 hours, making it useful for positron emission tomography (PET) imaging. It can be used to label radiopharmaceuticals and track their distribution in the body, providing information on the location and extent of disease.

It is important to note that handling and use of radioisotopes require specialized training and equipment due to their potential radiation hazards.

Nitrogen compounds are chemical substances that contain nitrogen, which is a non-metal in group 15 of the periodic table. Nitrogen forms compounds with many other elements due to its ability to form multiple bonds, including covalent bonds with hydrogen, oxygen, carbon, sulfur, and halogens.

Nitrogen can exist in several oxidation states, ranging from -3 to +5, which leads to a wide variety of nitrogen compounds with different properties and uses. Some common examples of nitrogen compounds include:

* Ammonia (NH3), a colorless gas with a pungent odor, used in fertilizers, cleaning products, and refrigeration systems.
* Nitric acid (HNO3), a strong mineral acid used in the production of explosives, dyes, and fertilizers.
* Ammonium nitrate (NH4NO3), a white crystalline solid used as a fertilizer and explosive ingredient.
* Hydrazine (N2H4), a colorless liquid with a strong odor, used as a rocket fuel and reducing agent.
* Nitrous oxide (N2O), a colorless gas used as an anesthetic and laughing gas in dental procedures.

Nitrogen compounds have many important applications in various industries, such as agriculture, pharmaceuticals, chemicals, and energy production. However, some nitrogen compounds can also be harmful or toxic to humans and the environment if not handled properly.

Tin radioisotopes refer to specific variants of the element tin that have unstable nuclei and emit radiation as they decay towards a more stable state. These isotopes are often produced in nuclear reactors or particle accelerators and can be used in a variety of medical applications, such as:

1. Medical Imaging: Tin-117m, for example, is used as a radiopharmaceutical in medical imaging studies to help diagnose various conditions, including bone disorders and liver diseases.
2. Radiation Therapy: Tin-125 can be used in the treatment of certain types of cancer, such as prostate cancer, through brachytherapy - a type of radiation therapy that involves placing a radioactive source directly into or near the tumor.
3. Radioisotope Production: Tin-106 is used as a parent isotope in the production of other medical radioisotopes, such as iodine-125 and gallium-67.

It's important to note that handling and using radioisotopes requires specialized training and equipment due to their potential radiation hazards.

Carbon radioisotopes are radioactive isotopes of carbon, which is an naturally occurring chemical element with the atomic number 6. The most common and stable isotope of carbon is carbon-12 (^12C), but there are also several radioactive isotopes, including carbon-11 (^11C), carbon-14 (^14C), and carbon-13 (^13C). These radioisotopes have different numbers of neutrons in their nuclei, which makes them unstable and causes them to emit radiation.

Carbon-11 has a half-life of about 20 minutes and is used in medical imaging techniques such as positron emission tomography (PET) scans. It is produced by bombarding nitrogen-14 with protons in a cyclotron.

Carbon-14, also known as radiocarbon, has a half-life of about 5730 years and is used in archaeology and geology to date organic materials. It is produced naturally in the atmosphere by cosmic rays.

Carbon-13 is stable and has a natural abundance of about 1.1% in carbon. It is not radioactive, but it can be used as a tracer in medical research and in the study of metabolic processes.

I'm sorry for any confusion, but "nitrogen cycle" is not a medical term. It is a biological concept that refers to the process through which nitrogen, an essential element for life, is converted between various chemical forms as it circulates through the atmosphere, terrestrial ecosystems, and aquatic environments.

The nitrogen cycle includes several key processes:

1. Nitrogen fixation: Certain bacteria are capable of converting atmospheric nitrogen (N2) into ammonia (NH3), a form that can be used by plants and other organisms. This process is called nitrogen fixation.
2. Nitrification: Some types of bacteria convert ammonia into nitrites (NO2-) and then into nitrates (NO3-). This two-step process is known as nitrification.
3. Denitrification: Certain bacteria can convert nitrates back into nitrogen gas, releasing it into the atmosphere. This process is called denitrification.
4. Assimilation: Plants and other organisms take up nitrogen in the form of ammonia or nitrates from the soil or water and incorporate it into their tissues through a process called assimilation.
5. Ammonification: When organisms die and decompose, or when they excrete waste products, nitrogen is released back into the environment in the form of ammonia. This process is known as ammonification.

While not a medical term, understanding the nitrogen cycle is important for many areas of science, including environmental science, agriculture, and ecology.

Blood Urea Nitrogen (BUN) is a laboratory value that measures the amount of urea nitrogen in the blood. Urea nitrogen is a waste product that is formed when proteins are broken down in the liver. The kidneys filter urea nitrogen from the blood and excrete it as urine.

A high BUN level may indicate impaired kidney function, as the kidneys are not effectively removing urea nitrogen from the blood. However, BUN levels can also be affected by other factors such as dehydration, heart failure, or gastrointestinal bleeding. Therefore, BUN should be interpreted in conjunction with other laboratory values and clinical findings.

The normal range for BUN is typically between 7-20 mg/dL (milligrams per deciliter) or 2.5-7.1 mmol/L (millimoles per liter), but the reference range may vary depending on the laboratory.

Nitrogen dioxide (NO2) is a gaseous air pollutant and respiratory irritant. It is a reddish-brown toxic gas with a pungent, choking odor. NO2 is a major component of smog and is produced from the combustion of fossil fuels in vehicles, power plants, and industrial processes.

Exposure to nitrogen dioxide can cause respiratory symptoms such as coughing, wheezing, and difficulty breathing, especially in people with asthma or other respiratory conditions. Long-term exposure has been linked to the development of chronic lung diseases, including bronchitis and emphysema. NO2 also contributes to the formation of fine particulate matter (PM2.5), which can penetrate deep into the lungs and cause additional health problems.

"Iron radioisotopes" refer to specific forms of the element iron that have unstable nuclei and emit radiation. These isotopes are often used in medical imaging and treatment procedures due to their ability to be detected by specialized equipment. Common iron radioisotopes include Iron-52, Iron-55, Iron-59, and Iron-60. They can be used as tracers to study the distribution, metabolism, or excretion of iron in the body, or for targeted radiation therapy in conditions such as cancer.

Copper radioisotopes are radioactive isotopes or variants of the chemical element copper. These isotopes have an unstable nucleus and emit radiation as they decay over time. Copper has several radioisotopes, including copper-64, copper-67, and copper-60, among others. These radioisotopes are used in various medical applications such as diagnostic imaging, therapy, and research. For example, copper-64 is used in positron emission tomography (PET) scans to help diagnose diseases like cancer, while copper-67 is used in targeted radionuclide therapy for cancer treatment. The use of radioisotopes in medicine requires careful handling and regulation due to their radiation hazards.

Phosphorus radioisotopes are radioactive isotopes or variants of the element phosphorus that emit radiation. Phosphorus has several radioisotopes, with the most common ones being phosphorus-32 (^32P) and phosphorus-33 (^33P). These radioisotopes are used in various medical applications such as cancer treatment and diagnostic procedures.

Phosphorus-32 has a half-life of approximately 14.3 days and emits beta particles, making it useful for treating certain types of cancer, such as leukemia and lymphoma. It can also be used in brachytherapy, a type of radiation therapy that involves placing a radioactive source close to the tumor.

Phosphorus-33 has a shorter half-life of approximately 25.4 days and emits both beta particles and gamma rays. This makes it useful for diagnostic procedures, such as positron emission tomography (PET) scans, where the gamma rays can be detected and used to create images of the body's internal structures.

It is important to note that handling and using radioisotopes requires specialized training and equipment to ensure safety and prevent radiation exposure.

Beta particles, also known as beta rays, are a type of ionizing radiation that consist of high-energy electrons or positrons emitted from the nucleus of certain radioactive isotopes during their decay process. When a neutron in the nucleus decays into a proton, it results in an excess energy state and one electron is ejected from the atom at high speed. This ejected electron is referred to as a beta particle.

Beta particles can have both positive and negative charges, depending on the type of decay process. Negative beta particles (β−) are equivalent to electrons, while positive beta particles (β+) are equivalent to positrons. They possess kinetic energy that varies in range, with higher energies associated with greater penetrating power.

Beta particles can cause ionization and excitation of atoms and molecules they encounter, leading to chemical reactions and potential damage to living tissues. Therefore, appropriate safety measures must be taken when handling materials that emit beta radiation.

Technetium is not a medical term itself, but it is a chemical element with the symbol Tc and atomic number 43. However, in the field of nuclear medicine, which is a branch of medicine that uses small amounts of radioactive material to diagnose or treat diseases, Technetium-99m (a radioisotope of technetium) is commonly used for various diagnostic procedures.

Technetium-99m is a metastable nuclear isomer of technetium-99, and it emits gamma rays that can be detected outside the body to create images of internal organs or tissues. It has a short half-life of about 6 hours, which makes it ideal for diagnostic imaging since it decays quickly and reduces the patient's exposure to radiation.

Technetium-99m is used in a variety of medical procedures, such as bone scans, lung scans, heart scans, liver-spleen scans, brain scans, and kidney scans, among others. It can be attached to different pharmaceuticals or molecules that target specific organs or tissues, allowing healthcare professionals to assess their function or identify any abnormalities.

Mercury radioisotopes refer to specific variants of the element mercury that have unstable nuclei and emit radiation as they decay towards a more stable state. These isotopes are often produced in nuclear reactors or particle accelerators for various medical, industrial, and research applications. In the medical field, mercury-203 (^203Hg) and mercury-207 (^207Hg) are used as gamma emitters in diagnostic procedures and therapeutic treatments. However, due to environmental and health concerns associated with mercury, its use in medical applications has significantly decreased over time.

Technetium Tc 99m Sulfur Colloid is a radioactive tracer used in medical imaging procedures, specifically in nuclear medicine. It is composed of tiny particles of sulfur colloid that are labeled with the radioisotope Technetium-99m. This compound is typically injected into the patient's body, where it accumulates in certain organs or tissues, depending on the specific medical test being conducted.

The radioactive emissions from Technetium Tc 99m Sulfur Colloid are then detected by a gamma camera, which produces images that can help doctors diagnose various medical conditions, such as liver disease, inflammation, or tumors. The half-life of Technetium-99m is approximately six hours, which means that its radioactivity decreases rapidly and is eliminated from the body within a few days.

Cobalt isotopes are variants of the chemical element Cobalt (Co) that have different numbers of neutrons in their atomic nuclei. This results in the different isotopes having slightly different masses and varying levels of stability.

The most naturally occurring stable cobalt isotope is Co-59, which contains 27 neutrons in its nucleus. However, there are also several radioactive isotopes of cobalt, including Co-60, which is a commonly used medical and industrial radioisotope.

Co-60 has 30 neutrons in its nucleus and undergoes beta decay, emitting gamma rays and becoming Nickel-60. It has a half-life of approximately 5.27 years, making it useful for a variety of applications, including cancer treatment, industrial radiography, and sterilization of medical equipment.

Other radioactive isotopes of cobalt include Co-57, which has a half-life of 271.8 days and is used in medical imaging, and Co-56, which has a half-life of just 77.2 seconds and is used in research.

Cesium is a chemical element with the atomic number 55 and the symbol Cs. There are several isotopes of cesium, which are variants of the element that have different numbers of neutrons in their nuclei. The most stable and naturally occurring cesium isotope is cesium-133, which has 78 neutrons and a half-life of more than 3 x 10^20 years (effectively stable).

However, there are also radioactive isotopes of cesium, including cesium-134 and cesium-137. Cesium-134 has a half-life of about 2 years, while cesium-137 has a half-life of about 30 years. These isotopes are produced naturally in trace amounts by the decay of uranium and thorium in the Earth's crust, but they can also be produced artificially in nuclear reactors and nuclear weapons tests.

Cesium isotopes are commonly used in medical research and industrial applications. For example, cesium-137 is used as a radiation source in cancer therapy and industrial radiography. However, exposure to high levels of radioactive cesium can be harmful to human health, causing symptoms such as nausea, vomiting, diarrhea, and potentially more serious effects such as damage to the central nervous system and an increased risk of cancer.

Cerium is a naturally occurring element found in the Earth's crust, and it has several radioisotopes, which are radioactive isotopes or forms of cerium. These isotopes have unstable nuclei that emit radiation as they decay into more stable forms. Here are some examples of cerium radioisotopes:

* Cerium-134: This radioisotope has a half-life of about 3.12 days, which means that half of its atoms will decay into other elements in this time period. It decays by emitting beta particles and gamma rays.
* Cerium-137: This is a long-lived radioisotope with a half-life of about 2.5 years. It decays by emitting beta particles and gamma rays, and it can be used in medical imaging and cancer treatment. However, if released into the environment, it can pose a radiation hazard to humans and other organisms.
* Cerium-141: This radioisotope has a half-life of about 32.5 days, and it decays by emitting beta particles and gamma rays. It is produced in nuclear reactors and can be used for research purposes.
* Cerium-144: This radioisotope has a half-life of about 284 days, and it decays by emitting beta particles and gamma rays. It is produced in nuclear reactors and can be used for research purposes.

It's important to note that handling and working with radioisotopes requires proper training and protective measures to ensure safety and prevent radiation exposure.

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

I'm sorry for any confusion, but Hafnium is not a medical term. It is a chemical element with the symbol Hf and atomic number 72. Hafnium is a lustrous, silvery, tetravalent transition metal that chemically resembles zirconium and is found in zirconium minerals.

It has no relevance to medical terminology or healthcare. If you have any questions related to medical definitions or health-related topics, I'd be happy to try to help with those instead!

Isotope labeling is a scientific technique used in the field of medicine, particularly in molecular biology, chemistry, and pharmacology. It involves replacing one or more atoms in a molecule with a radioactive or stable isotope of the same element. This modified molecule can then be traced and analyzed to study its structure, function, metabolism, or interaction with other molecules within biological systems.

Radioisotope labeling uses unstable radioactive isotopes that emit radiation, allowing for detection and quantification of the labeled molecule using various imaging techniques, such as positron emission tomography (PET) or single-photon emission computed tomography (SPECT). This approach is particularly useful in tracking the distribution and metabolism of drugs, hormones, or other biomolecules in living organisms.

Stable isotope labeling, on the other hand, employs non-radioactive isotopes that do not emit radiation. These isotopes have different atomic masses compared to their natural counterparts and can be detected using mass spectrometry. Stable isotope labeling is often used in metabolic studies, protein turnover analysis, or for identifying the origin of specific molecules within complex biological samples.

In summary, isotope labeling is a versatile tool in medical research that enables researchers to investigate various aspects of molecular behavior and interactions within biological systems.

Gold radioisotopes are unstable forms of gold that emit radiation as they decay into more stable elements. They are not typically used for medical purposes, but there have been some experimental uses in the treatment of cancer. For example, Gold-198 is a radioisotope that has been used in the brachytherapy (internal radiation therapy) of certain types of tumors. It releases high-energy gamma rays and is often used as a sealed source for the treatment of cancer.

It's important to note that the use of radioisotopes in medicine, including gold radioisotopes, should only be performed under the supervision of trained medical professionals and radiation safety experts due to the potential risks associated with radiation exposure.

Lead radioisotopes refer to specific types of radioactive isotopes (or radionuclides) of the element lead. These isotopes have unstable nuclei and emit radiation as they decay over time, changing into different elements in the process. Examples of lead radioisotopes include lead-210, lead-212, and lead-214. These isotopes are often found in the decay chains of heavier radioactive elements such as uranium and thorium, and they have various applications in fields like nuclear medicine, research, and industrial radiography. However, exposure to high levels of radiation from lead radioisotopes can pose significant health risks, including damage to DNA and increased risk of cancer.

Diagnostic techniques using radioisotopes, also known as nuclear medicine, are medical diagnostic procedures that use small amounts of radioactive material, called radioisotopes or radionuclides, to diagnose and monitor various diseases and conditions. The radioisotopes are introduced into the body through different routes (such as injection, inhalation, or ingestion) and accumulate in specific organs or tissues.

The gamma rays or photons emitted by these radioisotopes are then detected by specialized imaging devices, such as gamma cameras or PET scanners, which generate images that provide information about the structure and function of the organ or tissue being examined. This information helps healthcare professionals to make accurate diagnoses, monitor disease progression, assess treatment response, and plan appropriate therapies.

Common diagnostic techniques using radioisotopes include:

1. Radionuclide imaging (also known as scintigraphy): A gamma camera is used to produce images of specific organs or tissues after the administration of a radioisotope. Examples include bone scans, lung scans, heart scans, and brain scans.
2. Positron emission tomography (PET) scans: A PET scanner detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide, such as fluorodeoxyglucose (FDG), which is often used in oncology to assess metabolic activity and identify cancerous lesions.
3. Single-photon emission computed tomography (SPECT): A specialized gamma camera rotates around the patient, acquiring multiple images from different angles that are then reconstructed into a 3D image, providing detailed information about organ function and structure.

Diagnostic techniques using radioisotopes offer several advantages, including high sensitivity, non-invasiveness, and the ability to assess both anatomical and functional aspects of organs and tissues. However, they also involve exposure to ionizing radiation, so their use should be balanced against potential risks and benefits, and alternative diagnostic methods should be considered when appropriate.

Zinc isotopes refer to variants of the chemical element zinc, each with a different number of neutrons in their atomic nucleus. Zinc has five stable isotopes: zinc-64, zinc-66, zinc-67, zinc-68, and zinc-70. These isotopes have naturally occurring abundances that vary, with zinc-64 being the most abundant at approximately 48.6%.

Additionally, there are also several radioactive isotopes of zinc, including zinc-65, zinc-71, and zinc-72, among others. These isotopes have unstable nuclei that decay over time, emitting radiation in the process. They are not found naturally on Earth and must be produced artificially through nuclear reactions.

Medical Definition: Zinc isotopes refer to variants of the chemical element zinc with different numbers of neutrons in their atomic nucleus, including stable isotopes such as zinc-64, zinc-66, zinc-67, zinc-68, and zinc-70, and radioactive isotopes such as zinc-65, zinc-71, and zinc-72.

Sulfur radioisotopes are unstable forms of the element sulfur that emit radiation as they decay into more stable forms. These isotopes can be used in medical imaging and treatment, such as in the detection and treatment of certain cancers. Common sulfur radioisotopes used in medicine include sulfur-35 and sulfur-32. Sulfur-35 is used in research and diagnostic applications, while sulfur-32 is used in brachytherapy, a type of internal radiation therapy. It's important to note that handling and usage of radioisotopes should be done by trained professionals due to the potential radiation hazards they pose.

Cadmium radioisotopes are unstable forms of the heavy metal cadmium that emit radiation as they decay into more stable elements. These isotopes can be created through various nuclear reactions, such as bombarding a cadmium atom with a high-energy particle. Some common cadmium radioisotopes include cadmium-109, cadmium-113, and cadmium-115.

These radioisotopes have a wide range of applications in medicine, particularly in diagnostic imaging and radiation therapy. For example, cadmium-109 is used as a gamma ray source for medical imaging, while cadmium-115 has been studied as a potential therapeutic agent for cancer treatment.

However, exposure to cadmium radioisotopes can also be hazardous to human health, as they can cause damage to tissues and organs through ionizing radiation. Therefore, handling and disposal of these materials must be done with care and in accordance with established safety protocols.

Astatine is a naturally occurring, radioactive, semi-metallic chemical element with the symbol At and atomic number 85. It is the rarest naturally occurring element in the Earth's crust, and the heaviest of the halogens. Astatine is not found free in nature, but is always found in combination with other elements, such as uranium and thorium.

Astatine is a highly reactive element that exists in several allotropic forms and is characterized by its metallic appearance and chemical properties similar to those of iodine. It has a short half-life, ranging from a few hours to a few days, depending on the isotope, and emits alpha, beta, and gamma radiation.

Due to its rarity, radioactivity, and short half-life, astatine has limited practical applications. However, it has been studied for potential use in medical imaging and cancer therapy due to its ability to selectively accumulate in tumors.

Radioimmunotherapy (RIT) is a medical treatment that combines the specificity of antibodies and the therapeutic effects of radiation to target and destroy cancer cells. It involves the use of radioactive isotopes, which are attached to monoclonal antibodies, that recognize and bind to antigens expressed on the surface of cancer cells. Once bound, the radioactivity emitted from the isotope irradiates the cancer cells, causing damage to their DNA and leading to cell death. This targeted approach helps minimize radiation exposure to healthy tissues and reduces side effects compared to conventional radiotherapy techniques. RIT has been used in the treatment of various hematological malignancies, such as non-Hodgkin lymphoma, and is being investigated for solid tumors as well.

Lutetium is a chemical element with the symbol Lu and atomic number 71. It is a rare earth metal that belongs to the lanthanide series. In its pure form, lutetium is a silvery-white metal that is solid at room temperature.

Medically, lutetium is used in the form of radioactive isotopes for diagnostic and therapeutic purposes. For example, lutetium-177 (^177Lu) is a radiopharmaceutical agent that can be used to treat certain types of cancer, such as neuroendocrine tumors. The radioactivity of ^177Lu can be harnessed to destroy cancer cells while minimizing damage to healthy tissue.

It's important to note that the use of lutetium in medical treatments should only be performed under the supervision of trained medical professionals, and with appropriate safety measures in place to protect patients and healthcare workers from radiation exposure.

I'm sorry for any confusion, but "Rhenium" is not a medical term. It is a chemical element with the symbol "Re" and atomic number 75. Rhenium is a heavy, silvery-white, metallic element that is highly resistant to corrosion and is used in high-temperature alloys and electronics.

It does not have any direct medical relevance or application as a drug, treatment, or diagnostic tool in human medicine. However, like many other elements, rhenium compounds are being studied for their potential medicinal uses, such as in cancer therapy. But it's important to note that these are still in the research phase and have not yet been approved for use in humans.

Samarium is not a medical term itself, but it is a chemical element with the symbol Sm and atomic number 62. It is a silvery-white metallic element that belongs to the lanthanide series in the periodic table.

However, samarium-153 (Sm-153) is a radioactive isotope of samarium that has medical applications. It is used as a therapeutic agent for the treatment of painful bone metastases, particularly in patients with prostate or breast cancer. Sm-153 is combined with a chelating agent to form a complex that can be injected into the patient's bloodstream. The chelating agent helps to ensure that the samarium is distributed throughout the body and is not taken up by healthy tissues. Once inside the body, Sm-153 emits beta particles, which can destroy cancer cells in the bones and relieve pain.

Therefore, while samarium is not a medical term itself, it does have medical applications as a therapeutic agent for the treatment of bone metastases.

Nitrogen oxides (NOx) are a group of highly reactive gases, primarily composed of nitric oxide (NO) and nitrogen dioxide (NO2). They are formed during the combustion of fossil fuels, such as coal, oil, gas, or biomass, and are emitted from various sources, including power plants, industrial boilers, transportation vehicles, and residential heating systems. Exposure to NOx can have adverse health effects, particularly on the respiratory system, and contribute to the formation of harmful air pollutants like ground-level ozone and fine particulate matter.

Radiopharmaceuticals are defined as pharmaceutical preparations that contain radioactive isotopes and are used for diagnosis or therapy in nuclear medicine. These compounds are designed to interact specifically with certain biological targets, such as cells, tissues, or organs, and emit radiation that can be detected and measured to provide diagnostic information or used to destroy abnormal cells or tissue in therapeutic applications.

The radioactive isotopes used in radiopharmaceuticals have carefully controlled half-lives, which determine how long they remain radioactive and how long the pharmaceutical preparation remains effective. The choice of radioisotope depends on the intended use of the radiopharmaceutical, as well as factors such as its energy, range of emission, and chemical properties.

Radiopharmaceuticals are used in a wide range of medical applications, including imaging, cancer therapy, and treatment of other diseases and conditions. Examples of radiopharmaceuticals include technetium-99m for imaging the heart, lungs, and bones; iodine-131 for treating thyroid cancer; and samarium-153 for palliative treatment of bone metastases.

The use of radiopharmaceuticals requires specialized training and expertise in nuclear medicine, as well as strict adherence to safety protocols to minimize radiation exposure to patients and healthcare workers.

Radioactive soil pollutants refer to radioactive substances that contaminate and negatively impact the chemical, physical, and biological properties of soil. These pollutants can arise from various sources such as nuclear accidents, industrial activities, agricultural practices, and military testing. They include radionuclides such as uranium, plutonium, cesium-137, and strontium-90, among others.

Exposure to radioactive soil pollutants can have serious health consequences for humans and other living organisms. Direct contact with contaminated soil can result in radiation exposure, while ingestion or inhalation of contaminated soil particles can lead to internal radiation exposure. This can increase the risk of cancer, genetic mutations, and other health problems.

Radioactive soil pollutants can also have negative impacts on the environment, such as reducing soil fertility, disrupting ecosystems, and contaminating water sources. Therefore, it is essential to monitor and regulate radioactive soil pollution to protect human health and the environment.

PII nitrogen regulatory proteins are a type of signal transduction protein involved in the regulation of nitrogen metabolism in bacteria and archaea. They are named "PII" because they contain two identical subunits, each with a molecular weight of approximately 12 kilodaltons. These proteins play a crucial role in sensing and responding to changes in the energy status and nitrogen availability within the cell.

The PII protein is composed of three domains: the T-domain, which binds ATP and ADP; the N-domain, which binds 2-oxoglutarate (an indicator of carbon and nitrogen status); and the B-domain, which is involved in signal transduction. The PII protein can exist in different conformational states depending on whether it is bound to ATP or ADP, and this affects its ability to interact with downstream effectors.

One of the primary functions of PII proteins is to regulate the activity of glutamine synthetase (GS), an enzyme that catalyzes the conversion of glutamate to glutamine. When nitrogen is abundant, PII proteins bind to GS and stimulate its activity, promoting the assimilation of ammonia into organic compounds. Conversely, when nitrogen is scarce, PII proteins dissociate from GS, allowing it to be inhibited by other regulatory proteins.

PII proteins can also interact with other enzymes and regulators involved in nitrogen metabolism, such as nitrogenase, uridylyltransferase/uridylyl-removing enzyme (UT/UR), and transcriptional regulators. Through these interactions, PII proteins help to coordinate the cell's response to changes in nitrogen availability and energy status, ensuring that resources are allocated efficiently and effectively.

Bromine radioisotopes are unstable forms of the element bromine that emit radiation as they decay into more stable forms. These isotopes can be used in various medical applications, such as diagnostic imaging and cancer treatment. Some commonly used bromine radioisotopes include Bromine-75, Bromine-76, and Bromine-77.

Bromine-75 is a positron-emitting radionuclide that can be used in positron emission tomography (PET) scans to image and diagnose various diseases, including cancer. It has a half-life of about 97 minutes.

Bromine-76 is also a positron-emitting radionuclide with a longer half-life of approximately 16.2 hours. It can be used in PET imaging to study the pharmacokinetics and metabolism of drugs, as well as for tumor imaging.

Bromine-77 is a gamma-emitting radionuclide with a half-life of about 57 hours. It can be used in various medical applications, such as in the labeling of antibodies and other biomolecules for diagnostic purposes.

It's important to note that handling and using radioisotopes require specialized training and equipment due to their potential radiation hazards.

Scintillation counting is a method used in medical physics and nuclear medicine to detect and quantify radioactivity. It relies on the principle that certain materials, known as scintillators, emit light flashes (scintillations) when they absorb ionizing radiation. This light can then be detected and measured to determine the amount of radiation present.

In a scintillation counting system, the sample containing radioisotopes is placed in close proximity to the scintillator. When radiation is emitted from the sample, it interacts with the scintillator material, causing it to emit light. This light is then detected by a photomultiplier tube (PMT), which converts the light into an electrical signal that can be processed and counted by electronic circuits.

The number of counts recorded over a specific period of time is proportional to the amount of radiation emitted by the sample, allowing for the quantification of radioactivity. Scintillation counting is widely used in various applications such as measuring radioactive decay rates, monitoring environmental radiation levels, and analyzing radioisotopes in biological samples.

A subdural effusion is an abnormal accumulation of fluid in the potential space between the dura mater (the outermost layer of the meninges that covers the brain and spinal cord) and the arachnoid membrane (one of the three layers of the meninges that surround the brain and spinal cord) in the subdural space.

Subdural effusions can occur due to various reasons, including head trauma, infection, or complications from neurosurgical procedures. The fluid accumulation may result from bleeding (subdural hematoma), inflammation, or increased cerebrospinal fluid pressure. Depending on the underlying cause and the amount of fluid accumulated, subdural effusions can cause various symptoms, such as headaches, altered mental status, or neurological deficits.

Subdural effusions are often asymptomatic and may resolve independently; however, in some cases, medical intervention might be necessary to alleviate the pressure on the brain or address the underlying condition. Imaging techniques like computed tomography (CT) or magnetic resonance imaging (MRI) scans are typically used to diagnose and monitor subdural effusions.

Calcium isotopes refer to variants of the chemical element calcium (ca) that have different numbers of neutrons in their atomic nuclei, and therefore differ in their atomic masses while having the same number of protons. The most common and stable calcium isotope is Calcium-40, which contains 20 protons and 20 neutrons. However, calcium has several other isotopes, including Calcium-42, Calcium-43, Calcium-44, and Calcium-46 to -52, each with different numbers of neutrons. Some of these isotopes are radioactive and decay over time. The relative abundances of calcium isotopes can vary in different environments and can provide information about geological and biological processes.

Radioactive waste is defined in the medical context as any material that contains radioactive nuclides in sufficient concentrations or for such durations that it is considered a threat to human health and the environment. It includes materials ranging from used hospital supplies, equipment, and substances contaminated with radionuclides, to liquids and gases released during the reprocessing of spent nuclear fuel.

Radioactive waste can be classified into two main categories:

1. Exempt waste: Waste that does not require long-term management as a radioactive waste due to its low activity and short half-life.
2. Radioactive waste: Waste that requires long-term management as a radioactive waste due to its higher activity or longer half-life, which can pose a threat to human health and the environment for many years.

Radioactive waste management is a critical aspect of nuclear medicine and radiation safety, with regulations in place to ensure proper handling, storage, transportation, and disposal of such materials.

Radio-iodinated serum albumin refers to human serum albumin that has been chemically bonded with radioactive iodine isotopes, typically I-125 or I-131. This results in a radiolabeled protein that can be used in medical imaging and research to track the distribution and movement of the protein in the body.

In human physiology, serum albumin is the most abundant protein in plasma, synthesized by the liver, and it plays a crucial role in maintaining oncotic pressure and transporting various molecules in the bloodstream. Radio-iodination of serum albumin allows for non-invasive monitoring of its behavior in vivo, which can be useful in evaluating conditions such as protein losing enteropathies, nephrotic syndrome, or liver dysfunction.

It is essential to handle and dispose of radio-iodinated serum albumin with proper radiation safety protocols due to its radioactive nature.

Radiometric dating is a method used to determine the age of objects, including rocks and other fossilized materials, based on the decay rates of radioactive isotopes. This technique relies on the fact that certain elements, such as carbon-14, potassium-40, and uranium-238, are unstable and gradually decay into different elements over time.

By measuring the ratio of the remaining radioactive isotope to the stable end product, scientists can calculate the age of a sample using the following formula:

age = (ln(Nf/N0)) / λ

where Nf is the number of atoms of the decayed isotope, N0 is the initial number of atoms of the radioactive isotope, and λ is the decay constant.

Radiometric dating has been used to date objects ranging from a few thousand years old to billions of years old, making it an essential tool for archaeologists, geologists, and other scientists who study the history of our planet.

Ruthenium radioisotopes refer to unstable isotopes of the element ruthenium, which decays or disintegrates spontaneously emitting radiation. Ruthenium is a rare transition metal with the atomic number 44 and has several radioisotopes, including ruthenium-97, ruthenium-103, ruthenium-105, and ruthenium-106. These radioisotopes have medical applications in diagnostic imaging, radiation therapy, and brachytherapy (a type of internal radiation therapy).

For instance, ruthenium-106 is used as a radiation source in ophthalmic treatments for conditions such as neovascular age-related macular degeneration and diabetic retinopathy. Ruthenium-103 is also used in brachytherapy seeds for the treatment of prostate cancer.

It's important to note that handling and using radioisotopes require specialized training, equipment, and safety measures due to their radiation hazards.

I'm sorry for any confusion, but 'Tungsten' is not a medical term. It is a chemical element with the symbol W and atomic number 74. Tungsten is a rare metal found naturally on Earth, and it has many industrial uses due to its hardness, high density, and high melting point.

In the context of medicine or healthcare, tungsten may be encountered in certain medical devices, such as X-ray tubes and electrodes, where its properties are utilized for their durability and heat resistance. However, it is not a term that would typically have a formal medical definition.

Isotopes are variants of a chemical element that have the same number of protons in their atomic nucleus, but a different number of neutrons. This means they have different atomic masses, but share similar chemical properties. Some isotopes are stable and do not decay naturally, while others are unstable and radioactive, undergoing radioactive decay and emitting radiation in the process. These radioisotopes are often used in medical imaging and treatment procedures.

Selenium radioisotopes are unstable forms of the element selenium that emit radiation as they decay into more stable forms. These isotopes can be produced through various nuclear reactions, such as irradiating a stable selenium target with protons or alpha particles. Some examples of selenium radioisotopes include selenium-75, selenium-79, and selenium-81.

Selenium-75 is commonly used in medical imaging to study the function of the thyroid gland, as it accumulates in this gland and can be detected using a gamma camera. Selenium-79 and selenium-81 have potential uses in cancer treatment, as they can be incorporated into compounds that selectively target and destroy cancer cells. However, more research is needed to fully understand the potential benefits and risks of using these radioisotopes in medical treatments.

It's important to note that handling and using radioisotopes requires special training and precautions, as they can be dangerous if not handled properly. Exposure to radiation from radioisotopes can increase the risk of cancer and other health problems, so it's essential to use them only under controlled conditions and with appropriate safety measures in place.

Alpha particles are a type of radiation that consist of two protons and two neutrons. They are essentially the nuclei of helium atoms and are produced during the decay of radioactive isotopes, such as uranium or radon. When an alpha particle is emitted from a radioactive atom, it carries away energy and causes the atom to transform into a different element with a lower atomic number and mass number.

Alpha particles have a positive charge and are relatively massive compared to other types of radiation, such as beta particles (which are high-energy electrons) or gamma rays (which are high-energy photons). Because of their charge and mass, alpha particles can cause significant ionization and damage to biological tissue. However, they have a limited range in air and cannot penetrate the outer layers of human skin, making them generally less hazardous than other forms of radiation if exposure is external.

Internal exposure to alpha-emitting radionuclides, however, can be much more dangerous because alpha particles can cause significant damage to cells and DNA when they are emitted inside the body. This is why inhaling or ingesting radioactive materials that emit alpha particles can pose a serious health risk.

Heterocyclic compounds are organic molecules that contain a ring structure made up of at least one atom that is not carbon, known as a heteroatom. These heteroatoms can include nitrogen, oxygen, sulfur, or other elements. In the case of "1-ring" heterocyclic compounds, the molecule contains a single ring structure composed of these heteroatoms and carbon atoms. Examples of 1-ring heterocyclic compounds include pyridine (contains one nitrogen atom in the ring), furan (contains one oxygen atom in the ring), and thiophene (contains one sulfur atom in the ring). These compounds play important roles in various biological processes and are also found in many drugs, dyes, and materials.

Sodium Pertechnetate Tc 99m is a radioactive pharmaceutical preparation used in medical diagnostic imaging. It is a technetium-99m radiopharmaceutical, where technetium-99m is a metastable nuclear isomer of technetium-99, which emits gamma rays and has a half-life of 6 hours. Sodium Pertechnetate Tc 99m is used as a contrast agent in various diagnostic procedures, such as imaging of the thyroid, salivary glands, or the brain, to evaluate conditions like inflammation, tumors, or abnormalities in blood flow. It is typically administered intravenously, and its short half-life ensures that the radiation exposure is limited.

In the context of medical definitions, 'carbon' is not typically used as a standalone term. Carbon is an element with the symbol C and atomic number 6, which is naturally abundant in the human body and the environment. It is a crucial component of all living organisms, forming the basis of organic compounds, such as proteins, carbohydrates, lipids, and nucleic acids (DNA and RNA).

Carbon forms strong covalent bonds with various elements, allowing for the creation of complex molecules that are essential to life. In this sense, carbon is a fundamental building block of life on Earth. However, it does not have a specific medical definition as an isolated term.

Gamma spectrometry is a type of spectrometry used to identify and measure the energy and intensity of gamma rays emitted by radioactive materials. It utilizes a device called a gamma spectrometer, which typically consists of a scintillation detector or semiconductor detector, coupled with electronic circuitry that records and analyzes the energy of each detected gamma ray.

Gamma rays are a form of ionizing radiation, characterized by their high energy and short wavelength. When they interact with matter, such as the detector in a gamma spectrometer, they can cause the ejection of electrons from atoms or molecules, leading to the creation of charged particles that can be detected and measured.

In gamma spectrometry, the energy of each detected gamma ray is used to identify the radioactive isotope that emitted it, based on the characteristic energy levels associated with different isotopes. The intensity of the gamma rays can also be measured, providing information about the quantity or activity of the radioactive material present.

Gamma spectrometry has a wide range of applications in fields such as nuclear medicine, radiation protection, environmental monitoring, and nuclear non-proliferation.

Ammonia is a colorless, pungent-smelling gas with the chemical formula NH3. It is a compound of nitrogen and hydrogen and is a basic compound, meaning it has a pH greater than 7. Ammonia is naturally found in the environment and is produced by the breakdown of organic matter, such as animal waste and decomposing plants. In the medical field, ammonia is most commonly discussed in relation to its role in human metabolism and its potential toxicity.

In the body, ammonia is produced as a byproduct of protein metabolism and is typically converted to urea in the liver and excreted in the urine. However, if the liver is not functioning properly or if there is an excess of protein in the diet, ammonia can accumulate in the blood and cause a condition called hyperammonemia. Hyperammonemia can lead to serious neurological symptoms, such as confusion, seizures, and coma, and is treated by lowering the level of ammonia in the blood through medications, dietary changes, and dialysis.

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

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

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

Pentetic Acid, also known as DTPA (Diethylenetriaminepentaacetic acid), is not a medication itself but a chelating agent used in the preparation of pharmaceutical products. A chelating agent is a compound that can form multiple bonds with metal ions, allowing them to be excreted from the body.

Pentetic Acid is used in medical treatments to remove or decrease the levels of certain toxic metals, such as lead, plutonium, americium, and curium, from the body. It can be given intravenously or orally, depending on the specific situation and the formulation of the medication.

It is important to note that the use of Pentetic Acid should be under the supervision of a healthcare professional, as it can also bind to essential metals like zinc, calcium, and iron, which can lead to deficiencies if not properly managed.

Tissue distribution, in the context of pharmacology and toxicology, refers to the way that a drug or xenobiotic (a chemical substance found within an organism that is not naturally produced by or expected to be present within that organism) is distributed throughout the body's tissues after administration. It describes how much of the drug or xenobiotic can be found in various tissues and organs, and is influenced by factors such as blood flow, lipid solubility, protein binding, and the permeability of cell membranes. Understanding tissue distribution is important for predicting the potential effects of a drug or toxin on different parts of the body, and for designing drugs with improved safety and efficacy profiles.

Fertilizers are substances that are added to soil to provide nutrients necessary for plant growth and development. They typically contain macronutrients such as nitrogen (N), phosphorus (P), and potassium (K) in forms that can be readily taken up by plants. These three nutrients are essential for photosynthesis, energy transfer, and the production of proteins, nucleic acids, and other vital plant compounds.

Fertilizers may also contain secondary nutrients like calcium (Ca), magnesium (Mg), and sulfur (S) as well as micronutrients such as iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), boron (B), and molybdenum (Mo). These elements play crucial roles in various plant metabolic processes, including enzyme activation, chlorophyll synthesis, and hormone production.

Fertilizers can be organic or synthetic. Organic fertilizers include materials like compost, manure, bone meal, and blood meal, which release nutrients slowly over time as they decompose. Synthetic fertilizers, also known as inorganic or chemical fertilizers, are manufactured chemicals that contain precise amounts of specific nutrients. They can be quickly absorbed by plants but may pose environmental risks if not used properly.

Proper fertilization is essential for optimal plant growth and crop yield. However, overuse or improper application of fertilizers can lead to nutrient runoff, soil degradation, water pollution, and other negative environmental impacts. Therefore, it's crucial to follow recommended fertilizer application rates and practices based on the specific needs of the plants and local regulations.

Radioisotope teletherapy is a type of cancer treatment that uses high-energy radiation from a radioisotope to destroy cancer cells. In this procedure, the radioisotope is placed outside the body and aimed at the tumor site, rather than being inserted into the body like in brachytherapy. The radiation travels through space and penetrates the tissue to reach the tumor, where it damages the DNA of cancer cells and inhibits their ability to divide and grow. This type of radiotherapy is often used for larger or more difficult-to-reach tumors, as well as for palliative care in advanced stages of cancer. Examples of radioisotopes commonly used in teletherapy include cobalt-60 and cesium-137.

In the context of medical research, "methods" refers to the specific procedures or techniques used in conducting a study or experiment. This includes details on how data was collected, what measurements were taken, and what statistical analyses were performed. The methods section of a medical paper allows other researchers to replicate the study if they choose to do so. It is considered one of the key components of a well-written research article, as it provides transparency and helps establish the validity of the findings.

Nuclear medicine is a branch of medical imaging that uses small amounts of radioactive material, called radiopharmaceuticals, to diagnose and treat various diseases. The radiopharmaceuticals are taken internally, usually through injection or oral administration, and accumulate in specific organs or tissues. A special camera then detects the radiation emitted by these substances, which helps create detailed images of the body's internal structures and functions.

The images produced in nuclear medicine can help doctors identify abnormalities such as tumors, fractures, infection, or inflammation. Additionally, some radiopharmaceuticals can be used to treat certain conditions, like hyperthyroidism or cancer, by delivering targeted doses of radiation directly to the affected area. Overall, nuclear medicine provides valuable information for the diagnosis, treatment planning, and monitoring of many medical conditions.

Carbon isotopes are variants of the chemical element carbon that have different numbers of neutrons in their atomic nuclei. The most common and stable isotope of carbon is carbon-12 (^{12}C), which contains six protons and six neutrons. However, carbon can also come in other forms, known as isotopes, which contain different numbers of neutrons.

Carbon-13 (^{13}C) is a stable isotope of carbon that contains seven neutrons in its nucleus. It makes up about 1.1% of all carbon found on Earth and is used in various scientific applications, such as in tracing the metabolic pathways of organisms or in studying the age of fossilized materials.

Carbon-14 (^{14}C), also known as radiocarbon, is a radioactive isotope of carbon that contains eight neutrons in its nucleus. It is produced naturally in the atmosphere through the interaction of cosmic rays with nitrogen gas. Carbon-14 has a half-life of about 5,730 years, which makes it useful for dating organic materials, such as archaeological artifacts or fossils, up to around 60,000 years old.

Carbon isotopes are important in many scientific fields, including geology, biology, and medicine, and are used in a variety of applications, from studying the Earth's climate history to diagnosing medical conditions.

Technetium Tc 99m Pentetate is a radioactive pharmaceutical preparation used as a radiopharmaceutical agent in medical imaging. It is a salt of technetium-99m, a metastable nuclear isomer of technetium-99, which emits gamma rays and has a half-life of 6 hours.

Technetium Tc 99m Pentetate is used in various diagnostic procedures, including renal imaging, brain scans, lung perfusion studies, and bone scans. It is distributed throughout the body after intravenous injection and is excreted primarily by the kidneys, making it useful for evaluating renal function and detecting abnormalities in the urinary tract.

The compound itself is a colorless, sterile, pyrogen-free solution that is typically supplied in a lead shielded container to protect against radiation exposure. It should be used promptly after preparation and handled with care to minimize radiation exposure to healthcare workers and patients.

Tritium is not a medical term, but it is a term used in the field of nuclear physics and chemistry. Tritium (symbol: T or 3H) is a radioactive isotope of hydrogen with two neutrons and one proton in its nucleus. It is also known as heavy hydrogen or superheavy hydrogen.

Tritium has a half-life of about 12.3 years, which means that it decays by emitting a low-energy beta particle (an electron) to become helium-3. Due to its radioactive nature and relatively short half-life, tritium is used in various applications, including nuclear weapons, fusion reactors, luminous paints, and medical research.

In the context of medicine, tritium may be used as a radioactive tracer in some scientific studies or medical research, but it is not a term commonly used to describe a medical condition or treatment.

Radiometry is the measurement of electromagnetic radiation, including visible light. It quantifies the amount and characteristics of radiant energy in terms of power or intensity, wavelength, direction, and polarization. In medical physics, radiometry is often used to measure therapeutic and diagnostic radiation beams used in various imaging techniques and cancer treatments such as X-rays, gamma rays, and ultraviolet or infrared light. Radiometric measurements are essential for ensuring the safe and effective use of these medical technologies.

Rosaniline dyes are a type of basic dye that were first synthesized in the late 19th century. They are named after rosaniline, which is a primary chemical used in their production. Rosaniline dyes are characterized by their ability to form complexes with metal ions, which can then bind to proteins and other biological molecules. This property makes them useful as histological stains, which are used to highlight specific structures or features within tissues and cells.

Rosaniline dyes include a range of different chemicals, such as methyl violet, crystal violet, and basic fuchsin. These dyes are often used in combination with other staining techniques to provide contrast and enhance the visibility of specific cellular components. For example, they may be used to stain nuclei, cytoplasm, or other structures within cells, allowing researchers and clinicians to visualize and analyze tissue samples more effectively.

It's worth noting that some rosaniline dyes have been found to have potential health hazards, particularly when used in certain forms or concentrations. Therefore, it's important to follow proper safety protocols when handling these chemicals and to use them only under the guidance of trained professionals.

"Nostoc commune" is not a medical term, but a scientific name for a type of cyanobacteria (blue-green algae). It's commonly found in various environments such as freshwater, soil, and on rocks. This organism can form colonies that appear as slimy, dark green or black mats.

While not a direct medical term, certain species of cyanobacteria, including Nostoc commune, can produce toxins that may pose health risks to humans and animals if ingested, inhaled, or contact skin. These toxins can cause various symptoms, such as rashes, nausea, vomiting, diarrhea, and liver damage. However, not all strains of Nostoc commune produce toxins, and the health risks associated with this specific species are relatively low compared to other cyanobacteria.

Nonetheless, it is essential to be aware of potential health hazards when encountering cyanobacterial blooms in recreational water bodies or drinking water sources and follow local guidelines for reporting and managing such incidents.

Quaternary ammonium compounds (QACs) are a group of disinfectants and antiseptics that contain a nitrogen atom surrounded by four organic groups, resulting in a charged "quat" structure. They are widely used in healthcare settings due to their broad-spectrum activity against bacteria, viruses, fungi, and spores. QACs work by disrupting the cell membrane of microorganisms, leading to their death. Common examples include benzalkonium chloride and cetyltrimethylammonium bromide. It is important to note that some microorganisms have developed resistance to QACs, and they may not be effective against all types of pathogens.

Whole-body counting is a non-invasive nuclear medicine technique used for the detection and measurement of radioactivity in the human body. It involves the use of sensitive radiation detectors that can measure the gamma rays emitted by radionuclides present within the body tissues.

The individual lies on a table or sits in a chair with their entire body inside a large detector, which is typically a scintillation camera or a NaI(Tl) crystal. The detector measures the number and energy of gamma rays emitted from the body, allowing for the identification and quantification of specific radionuclides present within the body.

Whole-body counting has several clinical applications, including monitoring patients who have received therapeutic radioisotopes, evaluating the effectiveness of radiation therapy, detecting and measuring internal contamination due to accidental exposure or intentional intake, and assessing the distribution and retention of radionuclides in research studies.

It is important to note that whole-body counting does not provide anatomical information like other imaging techniques (e.g., CT, MRI), but rather offers functional data on the presence and quantity of radioactivity within the body.

Potassium radioisotopes refer to unstable isotopes or variants of the element potassium that emit radiation as they decay towards a stable form. A common example is Potassium-40 (40K), which occurs naturally in small amounts in potassium-containing substances. It decays through beta decay and positron emission, as well as electron capture, with a half-life of approximately 1.25 billion years.

Radioisotopes like 40K have medical applications such as in dating archaeological artifacts or studying certain biological processes. However, exposure to high levels of radiation from potassium radioisotopes can be harmful and potentially lead to health issues like radiation sickness or cancer.

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