Advancements in Metabolic Studies Core
The Metabolic Studies Core has actively supported a number of high profile investigations and reports.
DHEA or Testosterone Replacement on Body Fatness and Metabolic/General Health Issues
Members of the Minnesota Obesity Center published a major study examining the effects of long-term DHEA or testosterone replacement on body fatness and a variety of metabolic/general health issues (Nair, K.S., Rizza, R.A., Khosla, S., O’Brien, P., Khatariya, K., Short, K.R., Nehra, A., Vittone, J.L., Klee, G.G., Basu, A., Basu, Cobelli, C, Toffolo, G, Man, CD, R., Tindall, D.J., Melton, L.J. III, Jensen, M.D. Effects of 2-year replacement of dehyrodepiandosterone replacement in elderly men and women and testosterone in men on physical performance, body composition, and bone density. NEJM 355: 1647-59, 2006). The body composition and energy expenditure components of the Metabolic Studies Core were utilized for this study.
We found that testosterone replacement in men with subnormal, but not frankly hypogonadal, levels of biologically available testosterone does not alter fat distribution, glucose, or lipid metabolism. It did result in a small, but significant improvement in bone density. We also report that DHEA replacement to youthful concentrations does not affect any relevant health parameter in elderly men or women with low endogenous DHEA levels. The Minnesota Obesity Center laid the infrastructure for this study by supporting the establishment of state-of-the-art DEXA and CT imaging techniques.
Menstrual Cycle Effect on Meal Fatty Acid Metabolism and Lipoprotein Lipase
The Metabolic Studies Core contributed to the assessment of the effects of the menstrual cycle on meal fatty acid metabolism (Uranga, A, Levine, J, Jensen MD. Isotope Tracer Measures of Meal Fatty Acid Metabolism: Reproducibility and Effects of the Menstrual Cycle. American Journal of Physiology, Endocrinology and Metabolism, 288: E547-E555, 2005) and the role of regional differences in lipoprotein lipase in body fat storage (Votruba, S.B and Jensen, M.D. Sex Specific Differences in Leg Fat Uptake are Revealed with a High Fat Meal. American Journal of Physiology, Endocrinology and Metabolism, 291: E1115-E1123, 2006).
Preadipocytes and Macrophages
A study supported by a pilot and feasibility grant from the Minnesota Obesity Center was published in Diabetologia. We describe for the first time the population of committed preadipocytes and macrophages in abdominal and femoral subcutaneous fat in upper body obese, lower body obese and non-obese women. (Committed Subcutaneous Preadipocytes are Reduced in Human Obesity. Diabetologia, 50:151-7 2007)
The Metabolic Studies Core supports the analysis of samples from Dr. Anne Sumner (NIH) collaborating with Dr. Jensen on the study of FFA metabolism in African-Americans. It also supports a collaboration between B. Baukol and Dr. Levine regarding physical activity in native American children (NCI), and between Dr Forrester and Dr Levine regarding physical activity in Urban dwellers and Agriculturalists (NIH).
Adipocyte Fatty Acid Transport Proteins and Trafficking
Dr. David Bernlohr, a basic scientist at the University of Minnesota is now a co-investigator on one of Dr. Jensen's NIH grants entitled “Regional Fatty Acid Metabolism in Humans. They are working together on the problem of adipocyte fatty acid transport proteins and fatty acid trafficking. The ongoing collaborative nature of the Minnesota Obesity Center promoted and has supported this relationship.