1. Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
2. Department of Gastroenterology and Hepatology, Saitama Medical Center, Saitama Medical University, Saitama, Japan
3. Department of Gastroenterology, Gifu Prefectural General Medical Center, Gifu, Japan
4. Third Department of Internal Medicine, University of Toyama, Toyama, Japan