1. Department of Gastroenterology Peking Union Medical College Hospital, Peking Union Medical College & Chinese Academy of Medical Science Beijing China
2. Medical Doctor Program, Peking Union Medical College & Chinese Academy of Medical Science Beijing China
3. Department of Internal Medicine Peking Union Medical College Hospital, Peking Union Medical College & Chinese Academy of Medical Science Beijing China
4. Department of Gastroenterology Beijing Hospital, National Center of Gerontology, Institute of Geriatric Medicine, Chinese Academy of Medical Science Beijing China
5. Department of Respiratory and Critical Care Medicine Peking Union Medical College Hospital, Peking Union Medical College & Chinese Academy of Medical Science Beijing China