[1] Sado Gen Hosp, Div Gastroenterol, Sado, Japan
[2] Niigata Univ, Grad Sch Med & Dent Sci, Div Gastroenterol & Hepatol, Niigata, Japan
[3] Univ Occupat & Environm Hlth, Sch Med, Dept Internal Med, Kitakyushu, Fukuoka, Japan
[4] Nagaoka Red Cross Hosp, Div Gastroenterol, Nagaoka, Niigata, Japan
[5] Niigata Univ, Grad Sch Med & Dent Sci, Div Mol & Diagnost Pathol, Niigata, Japan