1. Departments of Otolaryngology, Sapporo Medical University School of Medicine, Sapporo, Japan
2. Departments of Pathology, Sapporo Medical University School of Medicine, Sapporo, Japan
3. Departments of Microbiology, Sapporo Medical University School of Medicine, Sapporo, Japan
4. Departments of Pediatrics, Sapporo Medical University School of Medicine, Sapporo, Japan
5. Departments of Anatomy, Sapporo Medical University School of Medicine, Sapporo, Japan