1. Departments of Dermatology, Venereology, Allergology and Immunology; Dessau Medical Center; Auenweg 38 06847 Dessau Germany
2. Freiburg Vein Center; Zähringer Straße 14 79108 Freiburg Germany
3. Institute of Mathematics; Humboldt University of Berlin; Johann von Neumann Haus Rudower Chaussee 25 12489 Berlin Germany
4. Research Group Geriatrics; Charité Universitaëtsmedizin Berlin; Reinickendorfer Straße 61 13347 Berlin Germany