[1] Okayama Univ, Fac Med, Dept Gastroenterol & Hepatol, Dent & Pharmaceut Sci, 2-5-1 Shikata Cho,Kita Ku, Okayama 7008558, Japan
[2] Tsuyama Chuo Hosp, Dept Internal Med, 1756 Kawasaki, Tsuyama, Okayama 7080841, Japan
[3] Okayama Univ, Fac Med, Dept Pract Gastrointestinal endoscopy, Dent & Pharmaceut Sci, 2-5-1 Shikata Cho,Kita Ku, Okayama 7008558, Japan
[4] Himeji Red Cross Hosp, Dept Internal Med, 1-12-1 Shimoteno, Himeji, Hyogo 6708540, Japan