1. Department of Gastroenterology, Tianjin Medical University General Hospital, Tianjin 300052, P.R. China
2. Department of Gastroenterology, Tianjin Medical University Cancer Institute Hospital, Tianjin 300052, P.R. China
3. Department of Gastroenterology, Tianjin Nankai Hospital, Tianjin 300052, P.R. China
4. Department of Neurosurgery, Tianjin Medical University General Hospital, Tianjin 300052, P.R. China