1. Departments of Public Health, St. Marianna University School of Medicine, 2-16-1 Sugao, Miyamae-ku, Kawasaki 213
2. Department of Hygiene, Tokyo Dental College, 1-2-2 Masago, Chiba 260, Japan
3. Internal Medicine, St. Marianna University School of Medicine, 2-16-1 Sugao, Miyamae-ku, Kawasaki 213