1. Department of Gastroenterology, Dokkyo Medical University School of Medicine, 880 Kitakobayashi Mibu, Tochigi 321-0293, Japan
2. Department of Diagnostic Pathology, Dokkyo Medical University School of Medicine, 880 Kitakobayashi Mibu, Tochigi 321-0293, Japan
3. Masuyama Gastroenterology Clinic, 83-413 Kajiya Otawara, Tochigi 324-0046, Japan