1. Department of Gastrointestinal Surgery, First Hospital of Jilin University, Changchun, Jilin 130021, P.R. China
2. Department of Gastrointestinal Surgery, The Third Hospital of Jilin University, Changchun, Jilin 130033, P.R. China
3. Department of Physiology, College of Basic Medical Sciences, Jilin University, Changchun, Jilin 130021, P.R. China