1. Department of Clinical Physiology, Faculty of Medicine, King Abdualziz University, Jeddah, Saudi Arabia
2. Division of Gastroenterology, Department of Medicine, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia
3. College of Medicine, King Saud bin Abdulaziz University for Health Sciences, Jeddah, Saudi Arabia
4. Faculty of Pharmacy, King Abdualziz University, Jeddah, Saudi Arabia.