1. Analytical Research Laboratory, Asahi Kasei Corporation, Fuji, Shizuoka 416-8501, Japan, First Laboratory for Pharmacology, Asahi Kasei Corporation, Tagata, Shizuoka 410-2321, Japan, High Energy Medical Research Center, Fukui Medical University, Yoshida, Fukui 910-1193, Japan, Peptide Institute Inc., Minoh, Osaka 562-8686, Japan, and The Noguchi Institute, Itabashi, Tokyo 173-0003, Japan