1. Department of Veterinary Medicine, College of Bioresource Sciences; Nihon University; Fujisawa Kanagawa 252-0880 Japan
2. Institute of Clinical Medicine and Research; Jikei University School of Medicine; Kashiwa Chiba 277-8567 Japan
3. Agricultural and Veterinary Division, Meiji Seika Pharma Co.; Chuo-ku Tokyo 104-8002 Japan