1. Center for Diagnostic and Therapeutic Endoscopy Keio University School of Medicine Tokyo Japan
2. Division of Gastroenterology and Hepatology, Department of Internal Medicine Keio University School of Medicine Tokyo Japan
3. Department of Anatomy and Cell Biology University of Yamanashi Faculty of Medicine Yamanashi Japan
4. Department of Surgery Keio University School of Medicine Tokyo Japan
5. Center for Preventive Medicine Keio University School of Medicine Tokyo Japan