1. Division of Oral Ecology and Biochemistry; Tohoku University Graduate School of Dentistry
2. Department of Thoracic Surgery; Institute of Development, Aging, and Cancer; Tohoku University
3. Division of Preventive Dentistry; Tohoku University Hospital; Sendai 980-8575 Japan
4. Department of Microbiology; Aichigakuin University School of Pharmacy; Nagoya 464-8650 Japan