1. Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba-yama, Aoba-ku, Sendai 980-8578, Japan, Faculty of Pharmaceutical Sciences, Nagasaki University, Bunkyo-machi, Nagasaki 852-8521, Japan, and Faculty of Pharmaceutical Sciences, Okayama University, Tsushima, Okayama 700-8530, Japan