1. Department of Gastroenterology, Rheumatology and Clinical Immunology Medicine, Sapporo Medical University School of Medicine, Sapporo, Hokkaido, Japan
2. Department of Internal Medicine, Dohkohkai Hospital, Sapporo, Hokkaido, Japan
3. Department of Pathology, Sapporo Medical University School of Medicine, Sapporo, Hokkaido, Japan
4. Department of Pathology, Teine Keijinkai Hospital, Sapporo, Hokkaido, Japan