1. Department of Gastroenterology and Hepatology Yokohama City University Graduate School of Medicine Kanagawa Japan
2. Department of Gastroenterology NTT Kanto Medical Center Tokyo Japan
3. Department of Pathology Yokohama City University Hospital Kanagawa Japan
4. Department of Gastroenterology Aizu Central Hospital Fukushima Japan
5. Department of Gastroenterology Kawasaki Medical University Okayama Japan