1. Division of Gastroenterology and Hepatology; Department of Internal Medicine; Jikei University School of Medicine Katsushika Medical Center; Katsushika-Ku; Tokyo; Japan
2. Department of Gastroenterology and Hepatology; Shinmatsudo Central General Hospital; Matsudo City Chiba; Japan
3. Institute of Clinical Medicine and Research; The Jikei University School of Medicine; Kashiwa City Chiba; Japan