[1] Tohoku Univ, Grad Sch Med, Dept Internal Med & Rehabil Sci, Sendai, Miyagi 980, Japan
[2] Fukuoka Univ, Sch Med, Dept Internal Med 4, Fukuoka 81401, Japan
[3] Hirosaki Univ, Sch Med, Dept Lab Med, Hirosaki, Aomori 036, Japan
[4] Sendai Shakaihoken Hosp, Dept Internal Med, Sendai, Miyagi, Japan