1. Department of Endoscopy, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan
2. Department of Medicine, Yonabaru Chuo Hospital, Okinawa, Japan
3. Department of Digestive and General Surgery, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan
4. Department of Infectious Diseases, Respiratory, and Digestive Medicine, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan