1. Department of Pharmacology & Therapeutics, Sana'a University, Sana'a Republic of Yemen
2. Department of Internal Medicine, Faculty of Medicine & Health Sciences, Sana'a University, Sana'a Republic of Yemen
3. Department of Mathematics, Faculty of Sciences, Sana'a University, Sana'a Republic of Yemen
4. Department of Gastroenterology, Charing Cross Hospital, London, UK