1. Department of Gastroenterology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, 524-001, People's Republic of China
2. Brain Korea 21 Four Project for Medical Science, Chungnam National University, Daejeon 35015, Korea
3. Departments of Medical Science and Department of Infection Biology, Chungnam National University College of Medicine, Daejeon 35015, Korea
4. Stem Cell Research & Cellular Therapy Center, Affiliated Hospital of Guangdong Medical University, Zhanjiang, 524-001, People's Republic of China