1. Division of Gastroenterology and Hepatology, Department of Internal Medicine, School of Medicine, Keio University, Tokyo, Japan
2. Center for Diagnostic and Therapeutic Endoscopy, School of Medicine, Keio University, Tokyo, Japan
3. Miyarisan Pharmaceutical Co., Ltd, Tokyo, Japan
4. Division of Gastroenterology and Hepatology, Tokyo Medical University, Ibaraki Medical Center, Ibaraki, Japan