1. I. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
2. Department of Anatomy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
3. GastroZentrum Hirslanden, Zürich, Switzerland
4. Interdisciplinary Endoscopy, University Hospital Hamburg-Eppendorf, Hamburg, Germany
5. Institute of Pathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
6. Department of Gastroenterology, Städtisches Krankenhaus Kiel, Kiel, Germany
7. Zentrum für Innere Medizin II, Städtisches Klinikum Brandenburg GmbH, Brandenburg an der Havel, Germany