1. University of Groningen, University Medical
Center Groningen, P.O. Box 30.033, 9700
RM Groningen, The Netherlands.
2. Medical Center Leeuwarden, P.O.
Box 888, 8901 BR Leeuwarden, The Netherlands.
3. Isala Hospital, P.O.
Box 10.400, 8000 GK Zwolle, The
Netherlands.
4. University of Groningen, University Medical
Center Groningen, P.O. Box 30.001, 9700
RB Groningen, The Netherlands.
5. Martini Hospital, P.O.
Box 30.033, 9700 RM Groningen, The
Netherlands.