[1] Yamaguchi Univ, Dept Gastroenterol & Hepatol, Grad Sch Med, Ube, Yamaguchi 755, Japan
[2] Yamaguchi Univ, Hlth Adm Ctr, Ube, Yamaguchi 755, Japan
[3] Yamaguchi Univ, Ctr Sci & Res, Ube, Yamaguchi 755, Japan
[4] Tokyo Med & Dent Univ, Dept Dev & Regenerat Biol, Tokyo, Japan