1. Department of Hematology, Hakodate Municipal Hospital, Hakodate 041-8680, Japan
2. Department of Internal Medicine, Hakodate Municipal Hospital, 1-10-1 Minato-Cho, Hakodate 041-8680, Japan
3. Department of Gastroenterology, Hakodate Municipal Hospital, Hakodate 041-8680, Japan
4. Department of Hematology and Oncology, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan
5. Department of Gastroentelology, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan