1. University Hospital Zurich, Zurich, Switzerland, and Assiut University Hospital; Assiut Egypt
2. University Hospital Zurich, Zurich, Switzerland, and Dr. I. Cantacuzino Hospital and Carol Davila University of Medicine and Pharmacy; Bucharest Romania
3. German Rheumatism Research Centre and Charité University Hospital; Berlin Germany
4. University Hospital Zurich; Zurich Switzerland