1. Department of Medical Laboratory Science, Faculty of Health Sciences; Hokkaido University, North-12, West-5; Kita-ku Sapporo 060-0812 Japan
2. Division of Biomedical Imaging Research; Juntendo University Graduate School of Medicine, 2-1-1 Hongo; Bunkyo-ku Tokyo 113-8421 Japan
3. Department of Microbiology; Gifu University School of Medicine, Yanagido 1-1; Gifu Gifu 501-1194 Japan