The Clinical Mass Spectrometry Core Lab collaborates with investigators from across the NIDDK Clinical Research Program 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 isotope, collecting samples, and monitoring production or decay in the isotopic ratio of the labeled product. Stable isotopes are advantageous for clinical studies as they are chemically and physically indistinguishable from the predominant natural isotope of the same element, however, they are readily distinguished and quantitated by isotope ratio mass spectrometers. The most commonly used stable isotopes are hydrogen(2H), oxygen(18O) and carbon(13C) and to a lesser extent nitrogen(15N) and sulfur(34S). 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 18oxygen. 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 covers a vast range. Currently we are developing the use of D or 13C labeled glucose as a measure of glucose metabolism and labeled 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.

Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Zip Code
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
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
Hall, Kevin D; Bemis, Thomas; Brychta, Robert et al. (2015) Calorie for Calorie, Dietary Fat Restriction Results in More Body Fat Loss than Carbohydrate Restriction in People with Obesity. Cell Metab 22:427-36
Chang, Yun C; Khanal Lamichhane, Ami; Garraffo, H Martin et al. (2014) Molecular mechanisms of hypoxic responses via unique roles of Ras1, Cdc24 and Ptp3 in a human fungal pathogen Cryptococcus neoformans. PLoS Genet 10:e1004292
Yadav, Hariom; Lee, Ji-Hyeon; Lloyd, John et al. (2013) Beneficial Metabolic Effects of a Probiotic via Butyrate-induced GLP-1 Hormone Secretion. J Biol Chem 288:25088-97