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Peter J. Walter, Ph.D.

Photo of Peter Walter
Scientific Focus Areas: Chemical Biology, Clinical Research

Professional Experience

  • Staff Scientist, NIDDK, NIH, 2008-present
  • Principal Research Scientist, U.S. Centers for Disease Control and Prevention, 2005-2008
  • Ph.D., Duquesne University

Research Goal

The mission of the NIDDK’s Clinical Mass Spectrometry Core (CMSC) is to collaborate with investigators from NIDDK and other institutes within NIH on quantitative mass spectrometry analyses. This includes the analysis of stable isotope tracer studies, doubly labeled water, drugs and drug metabolites, and small molecules by liquid chromatography–mass spectrometry (LC-MS), gas chromatography–mass spectrometry (GC-MS) and isotope ratio mass spectrometry (IRMS).

Current Research

The CMSC was initially established to support all stable isotope applications in NIDDK’s clinical labs and to advise, develop, and validate novel stable isotope-labeled research assays in collaboration with ongoing clinical research projects. Our primary emphasis was on the clinical measurement of total energy expenditure (TEE) by doubly labeled water (DLW). TEE is the total energy a person or animal uses in a day for activities, including rest. TEE is an important calculation used in determining dietary and exercise needs. It has been used extensively in obesity research.

Currently, one of the main emphasis of the CMSC is the measurement of metabolic parameters using stable isotope tracers and non-labeled metabolic tracers. These include but are not limited to 6,6-D2-Glucose, D5-glycerol, and U-13C-palmitate.

Key to the CMSC is also the quantitative measurement of drugs, drug metabolites and other small molecules by high resolution-accurate mass LC-MS and by triple quadrupole LC-MS. Alternatively, and for the same purposes, the CMSC performs quantitative analysis by GC-MS.

Select Publications

Regulation of Human Adipose Tissue Activation, Gallbladder Size, and Bile Acid Metabolism by a β3-Adrenergic Receptor Agonist.
Baskin AS, Linderman JD, Brychta RJ, McGehee S, Anflick-Chames E, Cero C, Johnson JW, O'Mara AE, Fletcher LA, Leitner BP, Duckworth CJ, Huang S, Cai H, Garraffo HM, Millo CM, Dieckmann W, Tolstikov V, Chen EY, Gao F, Narain NR, Kiebish MA, Walter PJ, Herscovitch P, Chen KY, Cypess AM.
Diabetes (2018 Oct) 67:2113-2125. Abstract/Full Text
Metreleptin-mediated improvements in insulin sensitivity are independent of food intake in humans with lipodystrophy.
Brown RJ, Valencia A, Startzell M, Cochran E, Walter PJ, Garraffo HM, Cai H, Gharib AM, Ouwerkerk R, Courville AB, Bernstein S, Brychta RJ, Chen KY, Walter M, Auh S, Gorden P.
J Clin Invest (2018 Aug 1) 128:3504-3516. Abstract/Full Text
View More Publications

Research in Plain Language

The mission of the NIDDK’s Clinical Mass Spectrometry Core (CMSC) is to collaborate with investigators from NIDDK and other institutes within NIH on quantitative mass spectrometry analyses. This includes the analysis of stable isotope tracer studies, doubly labeled water, drugs and drug metabolites, and small molecules by liquid chromatography–mass spectrometry (LC-MS), gas chromatography–mass spectrometry (GC-MS) and isotope ratio mass spectrometry (IRMS).