1. NMC Royal Hospital, Khalifa City, Abu Dhabi, United Arab Emirates
2. Internal Medicine Department, Medical Research and Clinical Studies Institute; The National Research Centre, Cairo, Egypt
3. National Institute of Chest and Allergy, Egypt
4. Internal Medicine Department, Zagazig Faculty of Medicine, Zagazig, Egypt
5. Intensive Care Department, Theodor Bilharz Research Institute, AL Warak, Giza Governorate, Egypt.