1. Department of Gastroenterology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing 400010, P.R. China
2. Teaching and Research Section of Forensic Medicine, College of Basic Medicine, Chongqing Medical University, Chongqing 400016, P.R. China
3. Department of Pain Management, Southwest Hospital, The First Affiliated Hospital of The Third Military Medical University, Chongqing 400038, P.R. China
4. Institute of Medicine and Hygienic Equipment for High Altitude Region, College of High Altitude Military Medicine, Third Military Medical University, Chongqing 400038, P.R. China