1. Department of Gastroenterology, Peking Union Medical College Hospital, Chinese Academy of Medical Science & Peking Union Medical College , Beijing, P. R. China
2. Eight-Year Medical Doctor Program, Chinese Academy of Medical Science & Peking Union Medical College , Beijing, P. R. China
3. Department of Gastroenterology, Shengjing Hospital of China Medical University, Shenyang , Liaoning, P. R. China
4. Department of Gastroenterology, Nanjing Drum Tower Hospital, School of Medicine, Nanjing University , Nanjing, Jiangsu, P. R. China
5. Department of Gastroenterology, The Sixth Affiliated Hospital, Sun Yat-sen University , Guangzhou, Guangdong, P. R. China
6. Department of Gastroenterology, Chongqing General Hospital , Chongqing, P. R. China
7. Department of Gastroenterology, Xijing Hospital of Digestive Diseases & State Key Laboratory of Cancer Biology, Fourth Military Medical University, Xi’an , Shaanxi, P. R. China
8. Department of Gastroenterology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University , Shanghai, P. R. China