1. Healthcare Research Institute, Wakunaga Pharmaceutical Company, Ltd., 1624 Shimokotachi, Kodacho, Akitakata, Hiroshima 739-1195, Japan; and Department of Molecular Biotechnology, Graduate School of Advanced Science of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashihiroshima, Hiroshima 739-8526, Japan