Human Energy and Body Weight Regulation Core

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Research highlights: 1. Brown adipose tissue continues to interest us as a potential source of increase energy expenditure non-pharmacologically. In collaboration with Dr. Celi, we have developed a new analytical technique to quantify the changes in the level of uptake 2-18F-fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography (PET) in the region of interest of common human brown fat. We have also validated this method against the current gold-standard of PET/CT for brown fat activity detection in our new protocol (12-Dk-0097). We found that to be a significant contributor to the inter-individual variability of non-shivering thermogenesis, even after controlling for age, gender, and other parameter. The implication of this study showed that brown fat activity may be an important component of non-shiver thermogenesis and PET scans may be sensitive enough to quantify its activation, which is superior to the traditionally visual detection. These findings will be reported in an original manuscript which is now under review by the Journal Diabetes. 2. Visceral fat has been found to correlate significantly with various cardiometabolic disease risk factors. We have collaborated with the manufacturer of the iDXA scanner and GE Global Research, using the newly-developed and validated CoreScan analysis capabilities to isolate the visceral fat volume in over 300 of the heterogeneous subjects we measured DXA body composition in the protocol 07-DK-0077. Preliminary findings suggest that visceral fat extracted from the simple DXA scans are reproducible, and is a stronger predictor of some common cardiometabolic disease risk biomarkers such as lipid profiles, insulin sensitivity index, when compared to BMI, waist circumferences, and conventionally DXA derived total and regional percent fat. These findings will be reported in an original manuscript which is now being submitted to American Journal of Clinical Nutrition. 3. Two new protocols have started in FY 2012 with our active involvements. Dr. Chris Ramsden (NIAAA) has started his protocol titled Dietary Essential Fatty Acid Regulation of Omega-3 HUFA Metabolism; Satiety and Body Composition (11-AA-0028). The main goal of this protocol is to study how diets differ in Omega-3 vs. Omega-6 fat affect body chemistry and hormone levels in women who are overweight or obese, with hope to be able to determine better diets or treatments to help people reach and maintain an optimum healthy weight. We are currently studying 11 subjects to date. Dr. Peter McGuire (NIGRI) has started his protocol titled The NIH UNI Study: Urea Cycle Disorders, Nutrition and Immunity (11-HG-0217), which aims to describe the nutritional and immune deficiencies seen, query for nutrition/enzymatic/immunologic correlations in this patient population, describe vaccine efficacy in this patient population, and search for new genes in rare families that have evidence for an unknown class of urea cycle disorder. The population will consist of patients previously evaluated at NIH, physician referrals, and families directed to the study from clinicaltrials.gov as well as the National Urea Cycle Disorders Foundation. This protocol is currently accruing new patients. Two other manuscripts were with extramural collaborators. Services rendered (FY12 activities): 24-hr energy expenditure by whole-room respiratory chambers (265), resting energy expenditure by metabolic carts (152), exercise and physical function testing (101), experimental satiety test (79), body composition (222 DXA, 324 Bod Pod), muscle biopsies (47), subcutaneous fat biopsies (23), and Health and Physical Exams (76).