1. Division of Gastroenterology and Hepatology, Department of Medicine, Nihon University School of Medicine, Nihon University Hospital, Chiyoda, Tokyo 101–8309, Japan
2. Department of Gastroenterology, Kitasato University School of Medicine, Sagamihara, Kanagawa 252–0374, Japan
3. Division of Oncologic Pathology, Department of Pathology and Microbiology, Nihon University School of Medicine, Nihon University Hospital, Chiyoda, Tokyo 101–8309, Japan