1. Departments of Physiology; Osaka Medical College; Takatsuki Osaka 569-8686 Japan
2. Otorhinolaryngology, Osaka Medical College; Takatsuki Osaka 569-8686 Japan
3. Microbiology, Osaka Medical College; Takatsuki Osaka 569-8686 Japan
4. Gene Function Research Laboratory; National Institute of Advanced Industrial Science and Technology; Tsukuba Ibaraki 305-8562 Japan