1. Drug Safety Research Laboratories, Shin Nippon Biomedical Laboratories, Ltd., 2438 Miyanoura, Kagoshima 891–1394, Japan
2. The United Graduate School of Veterinary Science, Yamaguchi University, 1677–1 Yoshida, Yamaguchi 753–8515, Japan
3. Department of Veterinary Pathology, Faculty of Agriculture, University of Miyazaki, 1–1 Gakuen Kibanadai-nishi, Miyazaki 889–2192, Japan