[1] Univ Tokyo, Dept Gastroenterol, Grad Sch Med, Bunkyo Ku, Tokyo 1138655, Japan
[2] Mitsui Mem Hosp, Dept Internal Med, Tokyo 101, Japan
[3] Kanto Cent Hosp, Dept Gastroenterol, Mutual Aid Assoc Publ Sch Teachers, Tokyo, Japan
[4] JR Tokyo Gen Hosp, Dept Gastroenterol, Tokyo, Japan
[5] Japanese Red Cross Med Ctr, Dept Gastroenterol, Tokyo, Japan