1. Division of Gastroenterology; Yokohama City University Graduate School of Medicine; 3-9 Fukuura, Kanazawa Yokohama 236-0004 Japan
2. Division of Gastroenterology; Tokyo Hiroo Metroporitan Hospital; Shibuya Japan
3. Division of Gastroenterology; NTT Kanto Medical Center; Tokyo Japan
4. Division of Gastroenterology; Machida Metroporitan Hospital; Machida Japan
5. Division of Gastroenterology; Hiratsuka City Hospital; Hiratsuka Japan
6. Division of Surgery; Yokohama City University; Yokohama Japan