1. Department of Gastroenterology and Nephrology; Graduate School of Medicine, Chiba University; Chiba Japan
2. Department of Gastroenterology; Kikkoman General Hospital; Noda Japan
3. Department of Gastroenterology; Kimitsu Chuo Hospital; Kisarazu Japan
4. Department of Surgery; Kimitsu Chuo Hospital; Kisarazu Japan
5. Department of Gastroenterology; Numazu City Hospital; Numazu Japan
6. Department of General Surgery; Graduate School of Medicine, Chiba University; Chiba Japan