Akira Hokama1, Yuiko Oishi1, Erika Koga1, Sayuri Takehara1, Jiro Fujita2. 1. Department of Endoscopy, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan. 2. Department of Infectious, Respiratory, and Digestive Medicine, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan.