1 Department of Gastroenterology, Dokkyo Medical University, Tochigi, Japan; Masuyama Gastrointestinal Clinic, Tochigi, Japan. tominaga@dokkyomed.ac.jp
2 Masuyama Gastrointestinal Clinic, Tochigi, Japan
3 Department of Gastroenterology, Dokkyo Medical University, Tochigi, Japan