1. Department of Gastroenterology; Yokohama City University, Graduate School of Medicine; Fukuura 3-9, Kanazawa Yokohama 236-0004 Japan
2. Department of Gastroenterology; Kanto Medical Center; Shinagawa Tokyo Japan
3. Department of Gastroenterological Surgery; Yokohama City University, Graduate School of Medicine; Yokohama Japan
4. Department of Pathology; Yokohama City University, Graduate School of Medicine; Yokohama Japan