1. St. Antonius Hospital, Nieuwegein, The Netherlands
2. University Medical Center, Utrecht, The Netherlands
3. Johns Hopkins Medical Institutions, Baltimore, Maryland, USA
4. Columbia University Medical Center, New York, New York, USA
5. University of Southern California, Los Angeles, California, USA
6. Canonsburg General Hospital, Canonsburg, Pennsylvania, USA
7. University of Rochester, Rochester, New York, USA
8. Academic Medical Center, Amsterdam, The Netherlands