1. Graduate School, Peking University China-Japan Friendship School of Clinical Medicine, Beijing, China
2. Department of Gastroenterology, Qilu Hospital, Shandong University, Jinan, China
3. Department of Gastroenterology, The First Affiliated Hospital of Soochow University, Suzhou, China
4. Graduate School, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
5. Department of Gastroenterology, Beijing Jishuitan Hospital, Beijing, China
6. Department of Gastrointestinal Surgery, China-Japan Friendship Hospital, Beijing, China
7. Department of Gastroenterology, China-Japan Friendship Hospital, Beijing, China