1. Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
2. Department of Medicine, Division of Diabetes, Endocrinology and Metabolism, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
3. Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
4. Department of Surgery, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
5. Vanderbilt Weight Loss Center, Vanderbilt University Medical Center, Nashville, TN 37204 USA.
6. VA Tennessee Valley Healthcare System, Nashville, TN 37212, USA.