1. Department of Medicine Division of Gastroenterology Brigham and Women's HospitalHarvard Medical SchoolBostonMassachusettsUSA
2. Departments of Medicine and Molecular Pharmacology Diabetes Research CenterAlbert Einstein College of MedicineBronxNew YorkUSA
3. Merck Research LaboratoriesRahwayNJ 07065USA
4. Department of Physiology and BiophysicsAlbert Einstein College of MedicineBronxNew YorkUSA
5. Research Division Joslin Diabetes CenterHarvard Medical SchoolBostonMassachusettsUSA
6. Division of Health and Sciences and TechnologyHarvard-Massachusetts Institute of TechnologyBostonMassachusettsUSA