1. Department of Chemistry, Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522, Japan
2. Department of Molecular Physiology, School of Medicine, Niigata University, Niigata 951-8510, Japan
3. Department of Otolaryngology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan