1. Department of Gastroenterology, Yantaishan Hospital, Yantai, Shandong, P.R. China
2. Department of General Surgery, Gaotang County People’s Hospital, Liaocheng, Shandong, P.R. China
3. Department of Cardiology, Qingdao Eighth People’s Hospital, Qingdao, Shandong, P.R. China
4. Department of Gastrointestinal Surgery, Laizhou People’s Hospital, Yantai, Shandong, P.R. China