1. Department of Public Health and Molecular Toxicology, School of Pharmaceutical Sciences, Kitasato University, Minato-ku, Tokyo 108-864, Pharmaceutical Research Center, Meiji Seika Kaisha, Ltd., Yokohama 222-3175, and Department of Molecular and Biochemical Toxicology, Faculty of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan