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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, lipidomics and small molecules by liquid chromatography–mass spectrometry (LC-MS) or isotope ratio mass spectrometry (IRMS).

Current Research

The Clinical Mass Spectrometry Core (CMSC) collaborates with investigators across NIDDK 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. One emphasis is 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, such as in obesity research.

Currently, one of the main emphasis 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, D1-Glucose, D5-glycerol, and U-13C-palmitate.

Key to the CMSC is also the quantitative measurement of drugs, drug metabolites, lipidomics and other small molecules by high resolution-accurate mass LC-MS and by triple quadrupole LC-MS.

Select Publications

Total energy expenditure in patients with colorectal cancer: associations with body composition, physical activity, and energy recommendations.
Purcell SA, Elliott SA, Walter PJ, Preston T, Cai H, Skipworth RJE, Sawyer MB, Prado CM.
Am J Clin Nutr (2019 Aug 1) 110:367-376. Abstract/Full Text
Ultra-Processed Diets Cause Excess Calorie Intake and Weight Gain: An Inpatient Randomized Controlled Trial of Ad Libitum Food Intake.
Hall KD, Ayuketah A, Brychta R, Cai H, Cassimatis T, Chen KY, Chung ST, Costa E, Courville A, Darcey V, Fletcher LA, Forde CG, Gharib AM, Guo J, Howard R, Joseph PV, McGehee S, Ouwerkerk R, Raisinger K, Rozga I, Stagliano M, Walter M, Walter PJ, Yang S, Zhou M.
Cell Metab (2019 Jul 2) 30:226. Abstract/Full Text
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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) and isotope ratio mass spectrometry (IRMS).