1. Medicinal Chemistry Research Laboratories, Medicinal Biology Research Laboratories, and New Drug Research Laboratories, Fujisawa Pharmaceutical Co. Ltd., 2-1-6 Kashima, Yodogawa-ku, Osaka 532, Japan, and Exploratory Research Laboratories, Fujisawa Pharmaceutical Co. Ltd., 5-2-3 Tokodai, Tsukuba, Ibaraki 300-26, Japan