Isotopes, stable tracers

Rabinowitz M, Wetherill GW, Kopple JD. 1974. Studies of human lead metabolism by use of stable isotope tracers. Environ Health Perspect 7 145-153. 

Wolfe has presented an excellent description of the systematic application of stable and radioactive isotope tracers in determining the kinetics of leucine metabolism and other amino acids in living systems. 

R. R. Wolfe (1992) Radioactive and Stable Isotope Tracers in Biomedicine, p. 357, Wiley-Liss, New York. 

Wolfe has presented an excellent description of the systematic application of stable and radioactive isotope tracers in determining the kinetics of substrate oxidation, carbon dioxide formation (including C02 breath tests), glucose oxidation, and fat oxidation in normal and diseased states. Quantification of the rate and extent of substrate oxidation can be achieved by using a specific or C-substrate which upon oxidation releases radioactive carbon dioxide. 

Miller et al., 1989 n = 6 children n = 3 n — 3 Age range 11-17 years 250 mg Ca as CCM enriched with tracer in form of chewable tablets Stable dual isotope tracers used to quantify CaAbs in urine and serum. Comparison of CCM chewable versus CCM swallowable supplements and CaCOa from data collected previously in same subjects Based on urinary excretion which correlated with serum data (r = 0.85) x SD% CaAbs from chewable CCM for molar ratio 6 2 3 (41.4 8.2%) > swallowable CCM for molar ratio 5 1 1 (39.5 10.6%) > CaCOa (26.7 7.8%) Chewable CCM > CaCOa (p =. 047) and swallowable CCM > CaCO (p =. 094)... 

Sabatier, M., Pont, F., Arnaud, M. J., and Tumlund, J. R. (2003). A compartmental model of magnesium metabolism in healthy men based on two stable isotope tracers. Am.. Physiol. Regul. Integr. Comp. Physiol. 285, R656-R663. 

Wolfe RR (1992) Radioactive and stable isotope tracers in biomedicine Principle and practice of kinetic analysis. Whiley-Liss, New York... 

A multiple ion collector device is required for the simultaneous determination of separated ion beams in precise and accurate isotope ratio measurements in order to study, for example, isotope fine variation in Nature or during tracer experiments using enriched stable isotope tracers. In thermal ionization mass spectrometers or in ICP-MS, mostly a system of several Faraday cups (up to 16) and/or ion counters (electron multipliers) is applied. In the photographs in Figures 4.7 and 4.8 examples of multiple ion collector systems are shown from the mass spectrometers MC-ICP-MS... 

Considerations in Stable-Isotope Experiments. Isotopic tracer additions should label the specific pool of interest quickly, before chemical or biological transformations of no interest distribute the tracer throughout the ecosystem. For calculation of transfers of material from one pool to another the isotope must be well mixed within the ecosystem in the compound it is supposed to trace, and the isotopic content between both pools should be given time to reach equilibrium. 

A large fraction of Emmett s research centered around iron catalysts and the application of both radioactive and stable isotopic tracers in catalysis. His studies of the iron-synthetic ammonia system led to conclusions that remain unchallenged to this day. 

Even though paleoaltimetric data from internal structural elements of orogenic belts and plateaus represent much needed complementary information to those derived from surface deposits or weathering products we caution about the uncritical use of stable isotopic data from deeper Earth environments in paleoaltimetric studies. It is highly desirable to obtain reliable thermometric, structural, and isotopic tracer data before attempting any paleoaltimetric reconstruction in such environments, as uncertainties exist about the fluid pathways and mechanisms responsible for fluid transport into the ductile crust. Maybe more importantly, it is imperative to document that the timing of meteoric water-rock interaction can be dated precisely, especially within thermally and kinematically rapidly evolving tectonic environments such as extensional detachment systems. 

Activation with 14 MeV neutrons has been used to determine the oxygen content of various metals such as beryllium 20>, Cl, F, O, Na, Si, and various rare earths in complex molten salt electrolytes 45>, the protein content of food products by means of the nitrogen content 46>, i60/180 and 14N/15N isotopic ratios in stable isotope tracer experiments 47,48), and in a wide variety of other applications. One application we... 

The role of metals and other elements in the health of humans, animals, and plants continues to be of great interest both on a routine basis and in research. Two recent reviews described the important impact of ICP-MS in biomedical research [227, 228]. ICP-MS provides the ability to measure multiple elements at ultratrace levels rapidly and to measure isotope ratios at low enough concentrations so that stable isotope tracers can be used for biomedical research [229]. Much remains unknown about the role of metals and their speciation on biological activity, in large part as a result of inadequate measurement techniques. 

Stable isotope tracers can be conveniently measured by using ICP-MS [259,260]. The low ICP-MS detection limits allow small amounts of stable isotope tracers to be given to subjects, including infants [261]. 

Maring, H., Settle, D. M., Buat-Meanard, P., Dulac, F., and Patterson, C. C. (1987). Stable lead isotope tracers of air mass trajectories in the Mediterranean region. Nature 330, 154—156. 

Food authentication, application of stable isotope tracers, characterization of complex metallobiomolecules, and investigation of their role in biological processes are all areas in which ICP-MS can play a more and more critical role. Speciation will continue to be a very dynamic field of investigation and the integration of speciation and metabolism studies with the use of stable isotopes as species-specific tracers is likely to become a research area of vital importance. On... 

P. B. Moser-Veillon, A. R. Mangels, K. Y. Patterson, C. Veillon, Utilization of two different chemical forms of selenium during lactation using stable isotope tracers an example of speciation in nutrition, Analyst, 117 (1992), 559D562. 

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