1. Department of Microbiology, Gifu University School of Medicine, Tsukasa-machi 40, Gifu City, Gifu 500,1
2. Department of Internal Medicine, Fuji National Hospital, Kamiide 814, Fujinomiya City, Shizuoka 418-01,2 and
3. Department of Internal Medicine (Neurology), Shinshu University School of Medicine, Asahi 3-1-1, Matumoto City, Nagano 390,3 Japan