1. Veterans Research and Education Foundation, Oklahoma City Veterans Affairs Health Care System, Oklahoma City, Oklahoma
2. The 1st Affiliated Hospital of Xi’an Jiaotong University, Shannxi, China
3. Department of Physiology, University of Oklahoma, Oklahoma City, Oklahoma
4. Division of Gastroenterology and Hepatology, Johns Hopkins Center for Neurogastroenterology, Baltimore, Maryland
5. Department of Gastroenterology, Tianjin No. 254 Hospital, Tianjin, China