1. Department of Medicine, University of California, San Diego, La Jolla, California 92093
2. Division of Periodontology, Department of Oral Bioscience, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8514, Japan
3. Division of Oral Science for Health Promotion, Laboratory of Periodontology and Immunology, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8514, Japan
4. Department of Radiotherapy, Beijing ChaoYang Hospital, Capital Medical University, Beijing 100020, China