1. Department of Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
2. Veteran Administration Surgical Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin, USA
3. Department of Medicine, Division of Gastroenterology, University of Chicago, Chicago, Illinois, USA
4. Department of Nutritional Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
5. Department of Surgery, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, China
6. Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA