1. Department of General Clinical Medicine, Ohu University School of Dentistry, 31-1 Mitsumido, Tomiya-machi, Koriyama City, Fukushima 963-8611, Japan
2. National Institute of Sensory Organs, National Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro, Tokyo 152-8902, Japan
3. Department of Oral Function and Molecular Biology, Ohu University School of Dentistry, 31-1 Mitsumido, Tomiya-machi, Koriyama City, Fukushima 963-8611, Japan