1. Department of Gastroenterology and Hepatology, International University of Health and Welfare, Narita Hospital, Narita 286-8520, Japan
2. Gastroenterology, Toyoshima Endoscopy Clinic, Tokyo 157-0066, Japan
3. Division of Gastroenterology and Hepatology, Department of Internal Medicine, Tokai University School of Medicine, Isehara 259-1193, Japan