1. The NHC Key Laboratory of Drug Addiction Medicine, The First Affiliated Hospital of Kunming Medical University, Kunming, Yunnan 650032, P.R. China
2. Yunnan Institute of Digestive Disease, The First Affiliated Hospital of Kunming Medical University, Kunming, Yunnan 650032, P.R. China
3. Shanghai International Travel Healthcare Center, Shanghai 200000, P.R. China
4. Department of Surgery, College of Medicine and Life Sciences, University of Toledo, Toledo, OH 43614, USA