1. Clinical Research Fresenius Medical Care Deutschland GmbH Bad Homburg, Germany
2. Nephrology University Hospital of Albacete Albacete, Spain
3. Nephrology Hospital Universitario Puerta de Hierro Madrid, Spain
4. Nephrology Centrum Dializ Fresenius Nephrocare Gdansk, Poland
5. Nephrology Hospital Universitario Ramón y Cajal Madrid, Spain
6. Nephrology Klinika Nefroloqii Lodz, Poland
7. Nephrology Hospital Universitario Fundación Alcorcón Alcorcón, Spain
8. Dept. of Nephrology Ospedale Umberto I Rome, Italy