1. Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts.
2. Department of Surgery, Beth Israel Deaconess Medical Center, Boston, Massachusetts.
3. Harvard Catalyst Clinical Research Center, Beth Israel Deaconess Medical Center, Boston, Massachusetts.
4. Section of Integrative Physiology and Metabolism, Research Division, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts.
5. Department of Radiology, Beth Israel Deaconess Medical Center, Boston, Massachusetts.
6. Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland.