1. Nephrology Division, Medical Clinic I, Klinikum Grosshadern;
2. Medical Policlinic, Klinikum Innenstadt;
3. Institute for Clinical Chemistry and Biochemistry, University of Munich, Munich;
4. Dialysis Center, Augsburg; and
5. Fresenius HemoCare Adsorber Technology GmbH, St. Wendel, Germany