1. Department of Dental Basic Sciences, Section Oral Biochemistry, Academic Centre for Dentistry Amsterdam (ACTA), Vrije Universiteit and Universiteit van Amsterdam
2. Department of Internal Medicine, Rode Kruis Hospital, The Hague
3. DIANET Dialysis Centres, Utrecht
4. DIANET Dialysis Centres, Amsterdam
5. Department of Clinical Epidemiology and Biostatistics, Vrije Universiteit University Medical Centre, Amsterdam
6. Department of Nephrology, Institute for Cardiovascular Research, Vrije Universiteit Medical Centre, Amsterdam