1. Department of Nephrology, General University Hospital and First Faculty of Medicine, Charles University, 121 08 Prague, Czech Republic
2. Institute of Immunology and Microbiology, General University Hospital and First Faculty of Medicine, Charles University, 121 08 Prague, Czech Republic
3. Institute of Medical Biochemistry and Laboratory Diagnostics, General University Hospital and First Faculty of Medicine, Charles University, 121 08 Prague, Czech Republic
4. Statistical Unit, Institute for Clinical and Experimental Medicine, 140 21 Prague, Czech Republic
5. Division of Renal Diseases and Hypertension, University of Colorado Denver, Aurora, CO 800 45, USA