Human vitamin B 12 absorption measurement by accelerator mass spectrometry using specifically labeled 14 C-cobalamin
Year: 2006
Type: article
Abstract: There is a need for an improved test of human ability to assimilate dietary vitamin B(12). Assaying and understanding absorption and uptake of B(12) is important because defects can lead to hematological and neurological complications. Accelerator mass spectrometry is uniquely suited for assessing absorption and kinetics of carbon-14 ((14)C)-labeled substances after oral ingestion because it is more sensitive than decay counting and can measure levels of (14)C in microliter volumes of biological samples with negligible exposure of subjects to radioactivity. The test we describe employs amounts of B(12) in the range of normal dietary intake. The B(12) used was quantitatively labeled with (14)C at one particular atom of the dimethylbenzimidazole (DMB) moiety by exploiting idiosyncrasies of Salmonella metabolism. To grow aerobically on ethanolamine, Salmonella enterica must be provided with either preformed B(12) or two of its precursors, cobinamide and DMB. When provided with (14)C-DMB specifically labeled in the C2 position, cells produced (14)C-B(12) of high specific activity (2.1 GBq/mmol, 58 mCi/mmol) (1 Ci = 37 GBq) and no detectable dilution of label from endogenous DMB synthesis. In a human kinetic study, a physiological dose (1.5 microg, 2.2 kBq/59 nCi) of purified (14)C-B(12) was administered and showed plasma appearance and clearance curves consistent with the predicted behavior of the pure vitamin. This method opens new avenues for study of B(12) assimilation.
Authors: Colleen Carkeet, Stephen R. Dueker, Jozsef Lango, Bruce A. Buchholz, Joshua W. Miller, Ralph Green, Bruce D. Hammock, John R. Roth, Peter J. Anderson
Language: English
Subfield: Rheumatology
Field: Medicine
Domain: Health Sciences
Open Access status: green
Funders: U.S. Department of Energy, National Institutes of Health, National Institute of General Medical Sciences, National Institute of Diabetes and Digestive and Kidney Diseases, National Institute of Environmental Health Sciences, National Center for Research Resources, Lawrence Livermore National Laboratory
Awards: MECHANISMS OF OXIDANT INDUCED LYMPHOCYTE REGULATION, G1101028137, G1251846919, NIEHS Center for Health Effects of Agrochemicals, G1702950523, G2127093783, Biomarkers of Exposure to Hazardous Substances, G3177268909, B12 Absorption, Kinetics and Transcobalamin Genotype, G3691271572, BIOSYNTHESIS OF VITAMIN B12 AND ANAEROBIC METABOLISM, G3822785970, G5795548715, G622880495, G6231081993, The UC Davis Center for Children's Enviromental Health and Disease Prevention, G6445123630, G705326951, G728354795, Resource for the Development of Biomedical Accelerator Mass Spectrometry (AMS), Resource for the Development of Biomedical Accelerator Mass Spectrometry (AMS), G9000072037, G9000114809, G9000184706
OpenAlex ID: W2063983897