1. Department of Pathophysiology, College of High Altitude Military Medicine, Third Military Medical University, Chongqing 400038, P.R. China
2. Department of Cadre Ward, Air Force Hospital of Western Theater Command, Chengdu, Sichuan 610065, P.R. China
3. Institute of Hepatopancreatobiliary Surgery, Southwest Hospital, Third Military Medical University, Chongqing 400038, P.R. China
4. Department of General Surgery, Air Force Hospital of Western Theater Command, Chengdu, Sichuan 610065, P.R. China