1. Division of Pathology, Department of Toxicology, Tokyo Metropolitan Research Laboratory of Public Health, Hyakunincho, Shinjukuku, Tokyo 169,1
2. Department of Urology, Branch Hospital, Faculty of Medicine, The University of Tokyo, Mejirodai, Bunkyo-ku, Tokyo 112,2
3. Department of Urology, Mitui Memorial Hospital, Izumicho, Kanda, Tokyo 101,3
4. Department of Virology II, National Institute of Health, Toyama, Shinjukuku, Tokyo 162,4 and
5. Department of Hematology, Tokyo Metropolitan Institute of Gerontology, Sakaecho, Itabashiku, Tokyo 173,5 Japan