1. Center for Instrumental Analysis Kyoto Pharmaceutical University Misasagishichyonochyo 1 Yamashina-ku Kyoto 607-8412 Japan
2. Department of Pathology and Experimental Medicine Graduate School of Medical Sciences Kumamoto University Honjyo 1-1-1, Chyuo-ku Kumamoto 860-855 Japan
3. Department of Radioisotope Science Institute of Resource Development and Analysis Kumamoto University Honjyo 1-1-1, Chyuo-ku Kumamoto 860-8556 Japan
4. Division of Hematopoiesis, Joint Research Center for Human Retrovirus Infection Kumamoto University Honjyo 1-1-1, Chyuo-ku Kumamoto 860-8556 Japan