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Download Zinc isotopes in biology Oral tracers of enriched Zn and
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Stable isotope 64 Zn 66 Zn 67 Zn 68 Zn 70 Zn Relative atomic mass 63.929 142 65.926 034 66.927 128 67.924 845 69.925 32 Mole fraction 0.4917 0.2773 0.0404 0.1845 0.0061 Zinc isotopes in biology Oral tracers of enriched 67Zn and intravenously injected stable isotopic tracers with enriched 70 Zn are used simultaneously to determine the fraction of dietary zinc absorbed (FZA) in humans. FZA is used in studies of zinc metabolism and homeostasis (the tendency of a body to maintain relatively stable state, e.g., maintaining human body temperature at 37 °C). For example, zinc isotopic tracers can be administered to patients to determine if zinc absorption in their bodies may be impaired by ingestion of certain dietary supplements. One such study conducted with Peruvian women showed that prenatal iron supplements affected the absorption of zinc during pregnancy. Another isotope tracer study investigated zinc deficiency in children with Crohn’s disease (an inflammatory disease of the intestines, especially the colon and ileum) [32, 238-240]. Zinc radioisotopes (e.g. 65Zn) can also be used for determining zinc absorption in humans, but they are now used rarely because of radiation hazards [32, 241-243]. ZnO nanoparticles enriched with 67Zn are being studied for use as biological/environmental nanotoxicity tracers [32, 244]. Zinc isotopes in Earth/planetary science Molecules, atoms, and ions of the stable isotopes of zinc possess slightly different physical, chemical, and biological properties, and they commonly will be isotopically fractionated during physical, chemical, and biological processes, giving rise to variations in isotopic abundances and in atomic weights. There are measureable variations in the isotopic abundances of zinc in natural terrestrial materials (Figure 1). Stable zinc isotopes can be used as tracers to investigate biogeochemical and chemical processes in environmental contamination sites [245-248]. The isotope-amount ratio n(66 Zn)/n(64Zn) can be used as an environmental tracer for detecting the pathways of anthropogenic zinc [245-248]. Fig. 1: Variation in isotopic composition of selected zinc-bearing materials (modified from [249]). Zinc isotopes used as a source of radioactive isotope(s) The 68Zn (p, 2p) 67Cu reaction in which targets with zinc enriched in 68Zn are irradiated and the neutron induced reaction 67Zn (n, p) 67Cu are both processes for producing 67Cu for radiotherapy [32, 250]. Irradiation of 64 Zn with a deuteron (the nucleus of 2 H, consisting of a proton and a neutron) in a cyclotron will produce the radioisotope 64Cu, which can be used for therapeutic applications and diagnosis with positron emission tomography (PET) via the 64Zn (d, 2p) 64 Cu reaction [32, 251]. Glossary anthropogenic – resulting from human activity. [return] atomic number (Z) – The number of protons in the nucleus of an atom. atomic weight (relative mean atomic mass) – the sum of the products of the relative atomic mass and the mole fraction of each stable and long-lived radioactive isotope of that element in the sample. The symbol of the atomic weight of element E is A r(E), and the symbol of the atomic weight of an atom (isotope) of element E having mass number A is Ar( AE). Because relative atomic masses are scaled (expressed relative) to one-twelfth the mass of a carbon-12 atom, atomic weights are dimensionless. [return] CT scan (X-ray computed tomography or X-ray CT, computerized axial tomography scan or CAT scan) – a computerized tomography (CT) scan combines a series of X-ray images taken from different angles and uses computer processing to create cross-sectional images, or slices, of the bones, blood vessels and soft tissues inside your body [702]. cyclotron – an apparatus in which charged atomic and subatomic particles are accelerated by a rapidly varying (radio frequency) electric field while following an outward spiral path in a constant magnetic field. [return] electron – elementary particle of matter with a negative electric charge and a rest mass of about 9.109 × 10–31 kg. element (chemical element) – a species of atoms; all atoms with the same number of protons in the atomic nucleus. A pure chemical substance composed of atoms with the same number of protons in the atomic nucleus [703]. gamma rays (gamma radiation) – a stream of high-energy electromagnetic radiation given off by an atomic nucleus undergoing radioactive decay. The energies of gamma rays are higher than those of X-rays; thus, gamma rays have greater penetrating power. half-life (radioactive) – the time interval that it takes for the total number of atoms of any radioactive isotope to decay and leave only one-half of the original number of atoms. intravenous (IV) – administered into a vein. [return] isotope – one of two or more species of atoms of a given element (having the same number of protons in the nucleus) with different atomic masses (different number of neutrons in the nucleus). The atom can either be a stable isotope or a radioactive isotope. isotopic abundance (mole fraction or amount fraction) – the amount (symbol n) of a given isotope (atom) in a sample divided by the total amount of all stable and long-lived radioactive isotopes of the chemical element in the sample. [return] isotope-amount ratio (r) – amount (symbol n) of an isotope divided by the amount of another isotope of the chemical element in the same system [706]. [return] isotopic composition – number and abundance of the isotopes of a chemical element that are naturally occurring [706]. [return] isotopic fractionation (stable-isotope fractionation) – preferential enrichment of one isotope of an element over another, owing to slight variations in their physical, chemical, or biological properties [706]. [return] metabolism – the chemical processes that occur within a living organism in order to maintain life [708]. [return] neutron – an elementary particle with no net charge and a rest mass of about 1.675 × 10–27 kg, slightly more than that of the proton. All atoms contain neutrons in their nucleus except for protium (1H). [return] positron – the antimatter counterpart of the electron, with a mass identical to that of the electron and an equal but opposite (positive) charge. positron emission tomography (PET) scan – an imaging technique that is used to observe metabolic activity within the body. The system detects pairs of gamma rays emitted indirectly by a radioactive isotope used as a tracer, which emits positrons and which is introduced into the body on a biologically-active molecule. Three-dimensional images of the concentration of the radioactive isotope within the body are then constructed by computer analysis. The imaging often is performed with an X-ray CT scan in the same instrument. [return] proton – an elementary particle having a rest mass of about 1.673 × 10–27 kg, slightly less than that of a neutron, and a positive electric charge equal and opposite to that of the electron. The number of protons in the nucleus of an atom is the atomic number. [return] radioactive decay – the process by which unstable (or radioactive) isotopes lose energy by emitting alpha particles (helium nuclei), beta particles (positive or negative electrons), gamma radiation, neutrons or protons to reach a final stable energy state. radioactive isotope (radioisotope) – an atom for which radioactive decay has been experimentally measured (also see half-life). radiotherapy (radiation therapy) – the treatment of disease by means of radiation from radioactive substances or X-rays. stable isotope – an atom for which no radioactive decay has ever been experimentally measured. tracer - substance used for tracking purposes. [return] X-rays – electromagnetic radiation with a wavelength ranging from 0.01 to 10 nanometers— shorter than those of UV rays and typically longer than those of gamma rays. References 32. S. J. Adelstein, and Manning, Frederick J. Isotopes for medicine and the life sciences. National Academy Press, Washington D.C. (1995). 238. K. O’Brien, Zavaleta, N., Caulfield, L., Wen, J., and Abrams, S. Journal of Nutrition. 130 2251 (2000). 239. T. S. I. Inc. Stable Isotopes In Nutritional Studies. Trace Sciences International Inc. 2014 Feb. 25. http://www.tracesciences.com/nutritionalstudiesisotopes.html 240. I. J. Griffin, Kim, S.C., Hicks, P.D., Liang, L.K., and Abrams, S.A. Pediatric Research. 56 (2), 235 (2004). 241. K. B. Payton, Flanagan, P.R., Stinson, E.A., Chodirker, D.P., Chamberlain, M.J., and Valberg, L.S. Gastroenterology. 83 (6), 1264 (1982). 242. N. M. Lowe, Woodhouse, L.R., Matel, J.S., and King, J.C. American Journal of Clinical Nutrition. 71 (2), 523 (2000). 243. T. S. I. Inc. Zinc Isotopes. Trace Sciences International Inc. 2014 Feb. 26. http://www.tracesciences.com/zn.htm 244. A. D. Dybowska, Croteau, M.N., Misra, S.K., Berhanu, D., Luoma, S.N., Christian, P., O’Brien, P., and Valsami-Jones, E. Environmental Pollution. 159, 266 (2010). 245. Y. Sivry, Riotte, J., Sonke, J.E., Audry, S., Schafer, J., Viers, J., Blanc, G., Freydier, R., and Dupre, B. Chemical Geology. 255 295 (2008). 10.1016/j.chemgeo.2008.06.038 246. C. Cloquet, Carignan, J., and Libourel, G. Environmental Science & Technology. 40 (21), 6594 (2006). 247. J. Chen, Gaillardet, J., and Louvat, P. Environmental Science & Technology. 42 (17), 6494 (2008). 248. M. Bigalke, Weyer, S., Kobza, J., and Wilcke, W. Geochimica et Cosmochimica Acta. 74 (23), 6801 (2010). 10.1016/j.gca.2010.08.044 249. P. T. C. N. Maréchal, and F. Albarède. Chemical Geology. 156, 251 (1999). 250. T. Katabuchi, Watanabe, S., Ishioka, N.S., Iida, Y., Hanaoka, H., Endo, K., and Matsuhashi, S. Journal of Radioanalytical and Nuclear Chemistry. 277 (2), 467 (2008). 10.1007/s10967-007-7144-9 251. K. Abbas, Kozempel, J., Bonardi, M., Groppi, F., Alfarano, A., Holzwarth, U., Simonelli, F., Hofman, H., Horstmann, W., Menapace, E., Leseticky, L., and Gibson, N. Applied Radiation and Isotopes. 64 (9), 1001 (2006). 10.1016/j.apradiso.2005.12.021 702. M. Clinic. Test and Procedures: CT scan. 2016 June 22. http://www.mayoclinic.org/tests-procedures/ct-scan/basics/definition/prc-20014610 703. I. U. o. P. a. A. Chemistry. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Blackwell Scientific Publications, Oxford (1997). 706. Coplen. Rapid Communications in Mass Spectrometry. 25 (2011). 708. Merriam-Webster. metabolism. Merriam-Webster. 2016 June 22. http://www.merriamwebster.com/dictionary/metabolism