1. Nutrition and Obesity Research Center (NORC), Mass Spectrometry Core Facility, Department of Anesthesiology, University of Colorado School of Medicine, Aurora, CO 80045, U.S.A.
2. Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, U.S.A.
3. Denver VA Medical Center, Denver, CO 80220, U.S.A.
4. Translational Medicine Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, U.S.A.
5. Radiation Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, U.S.A.
6. Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, U.S.A.