1. Department of Gastroenterology, The 986 Air Force Hospital, Xi'an, Shaanxi 710000, P.R. China
2. Department of Digestive Surgery, Xi'an International Medical Center Hospital, Xi'an, Shaanxi 710100, P.R. China
3. Department of Endocrinology, Xi'an International Medical Center Hospital, Xi'an, Shaanxi 710100, P.R. China
4. Department of Gastroenterology, Xi'an International Medical Center Hospital, Xi'an, Shaanxi 710100, P.R. China