The Clinical Mass Spectrometry Core collaborates with investigators from across the NIDDK Clinical Research Program, NIDDK basic research program and collaborating institutes to conduct stable isotope tracer studies (human and mammalian sources). Clinical studies using stable isotopes involve administering a subject with substances labeled with rare, non-radioactive, stable isotopes, collecting samples, and monitoring production or decay of the isotopic ratio of the labeled product. Stable isotopes are advantageous for clinical studies as they are essentially chemically and physically indistinguishable from the predominant natural isotope of the same element, however, they are readily distinguished and quantitated by mass spectrometers. The most commonly used stable isotopes are hydrogen(2H), oxygen(18O) and carbon(13C) The doubly labeled water (DLW) method was developed to measure total energy expenditure. A person or animal is administered a dose of water enriched in deuterium, and 18-oxygen. Labeled hydrogen can only be lost through water, whereas oxygen can be lost as water or carbon dioxide. Calculating the rate of carbon dioxide production then yields a measure of total energy expenditure. Metabolic studies with stable isotopes cover a vast range. Currently we measure labeled glucose, glycerol, and free fatty acids. The lab will advise, develop and validate novel research assays in collaboration with on-going clinical research projects and actively seeks new areas for collaboration with staff from across the NIH community. The most common projects nowadays involve mass spectrometry quantitation, by GC-MS but especially by LC-MS, of many drugs, metabolites, or small molecule compounds. Beside quantitation, we have identified unknown metabolite or even contaminants, which provided new avenues for investigation.
| Baskin, Alison S; Linderman, Joyce D; Brychta, Robert J et al. (2018) Regulation of Human Adipose Tissue Activation, Gallbladder Size, and Bile Acid Metabolism by a ?3-Adrenergic Receptor Agonist. Diabetes 67:2113-2125 |
| Rother, Kristina I; Sylvetsky, Allison C; Walter, Peter J et al. (2018) Pharmacokinetics of Sucralose and Acesulfame-Potassium in Breast Milk Following Ingestion of Diet Soda. J Pediatr Gastroenterol Nutr 66:466-470 |
| Brown, Rebecca J; Valencia, Areli; Startzell, Megan et al. (2018) Metreleptin-mediated improvements in insulin sensitivity are independent of food intake in humans with lipodystrophy. J Clin Invest 128:3504-3516 |
| Sylvetsky, Allison C; Walter, Peter J; Garraffo, H Martin et al. (2017) Widespread sucralose exposure in a randomized clinical trial in healthy young adults. Am J Clin Nutr 105:820-823 |
| Carmona-Rivera, Carmelo; Purmalek, Monica M; Moore, Erica et al. (2017) A role for muscarinic receptors in neutrophil extracellular trap formation and levamisole-induced autoimmunity. JCI Insight 2:e89780 |
| Kerns, Jennifer C; Guo, Juen; Fothergill, Erin et al. (2017) Increased Physical Activity Associated with Less Weight Regain Six Years After ""The Biggest Loser"" Competition. Obesity (Silver Spring) 25:1838-1843 |
| Sylvetsky, Allison C; Bauman, Viviana; Blau, Jenny E et al. (2017) Plasma concentrations of sucralose in children and adults. Toxicol Environ Chem 99:535-542 |
| Fothergill, Erin; Guo, Juen; Howard, Lilian et al. (2016) Persistent metabolic adaptation 6 years after ""The Biggest Loser"" competition. Obesity (Silver Spring) 24:1612-9 |
| Howard, Louisa C; Liu, Chia-Ying; Purdy, Julia B et al. (2016) Lipolytic Rate Associated With Intramyocardial Lipid in an HIV Cohort Without Increased Lipolysis. J Clin Endocrinol Metab 101:151-6 |
| Sylvetsky, Allison C; Gardner, Alexandra L; Bauman, Viviana et al. (2015) Nonnutritive Sweeteners in Breast Milk. J Toxicol Environ Health A 78:1029-32 |
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