1. University Erlangen-Nuremberg, Medical Clinic 1, Erlangen, Germany
2. Technical University of Munich, Clinic and Polyclinic for dermatology and allergology Biederstein, Munich, Germany
3. University Hospital of Giessen, Central Interdisciplinary Visceral Medical Endoscopy (ZIVE), Giessen, Germany
4. Hospital Helios Schwerin, Clinic for Gastroenterology and Infectiology, Schwerin, Germany
5. Hospital St. Marien Amberg, Clinic for Internal Medicine II, Amberg, Germany
6. Practice Clinic Schwabach, Schwabach, Germany
7. Hospital Neumarkt, Medical Clinic 2, Neumarkt, Germany