1. Otto Loewi Research Center, Division of Physiology, Medical University of Graz, 8010 Graz, Austria
2. Department of Nephrology, Dialysis and Internal Diseases, Medical University of Warsaw, 02-097 Warsaw, Poland
3. Department of Internal Diseases, Nephrology and Dialysis, Military Institute of Medicine, 04-141 Warsaw, Poland
4. Department of Epidemiology and Biostatistics, National Research Institute of Mother and Child, 01-211 Warsaw, Poland