1. Department of Gastroenterology, Rheumatology, and Clinical Immunology, Sapporo Medical University, Japan
2. Division of Gastroenterology, Department of Internal Medicine, Sapporo Shirakaba-dai Hospital, Japan
3. Division of Gastroenterology and Hepatology, Department of Internal Medicine, St. Marianna University School of Medicine, Japan
4. Department of Pathology, Sapporo Shirakaba-dai Hospital, Japan
5. Department of Urology, Sapporo Medical University, Japan