1. Division of Gastroenterology and Hepatology, Nihon University School of Medicine, Japan
2. Department of Digestive Surgery, Nihon University School of Medicine, Japan
3. Division of Pathology, Nihon University School of Medicine, Japan
4. Department of Gastroenterology, Narita Memorial Hospital, Japan
5. Department of Pathology and Laboratory Medicine, Kyoto First Red Cross Hospital, Japan