1. Institute for Pathophysiology, West German Heart and Vascular Centre, University of Essen Medical School, University of Duisburg-Essen , Hufelandstr. 55, 45147 Essen , Germany
2. Department of General, Visceral and Transplant Surgery, University of Essen Medical School, University of Duisburg-Essen , Essen , Germany
3. Private Practice of General and Internal Medicine , Kölner Straße 68, Essen , Germany
4. Department of Mathematics and Technology, Koblenz University of Applied Sciences, Rhein-Ahr-Campus , Remagen , Germany