1. Digestive Disease Research Center, Digestive Disease Research Institute, Tehran University of Medical Sciences, Tehran, Iran
2. Gut and Liver Research Center, Mazandaran University of Medical Sciences, Sari, Iran
3. Department of Gastroenterology, Imam Khomeini Hospital, Tehran University of Medical Sciences, Tehran, Iran
4. Gastroenterology Department, Hormozgan Medical School, Hormozgan University of Medical Sciences, Hormozgan, Bandar-Abbas, Iran
5. Gastrointestinal and Liver Diseases Research Center, Guilan University of Medical Sciences (GUMS), Rasht, Iran
6. Digestive Research Center, Kerman University of Medical Sciences, Kerman, Iran