1. Vilhelm Magnus Laboratory for Neurosurgical ResearchInstitute for Surgical Research and Department of NeurosurgeryOslo University HospitalP.O. Box 4950, Nydalen0424OsloNorway
2. Institute of Clinical MedicineFaculty of MedicineUniversity of OsloP.O. Box 1112, Blindern0317OsloNorway
3. Institute for Molecular Medicine FinlandFIMMUniversity of HelsinkiTukholmankatu 800290HelsinkiFinland
4. Department of NeurosurgeryHelsinki University Hospital and Clinical NeurosciencesUniversity of HelsinkiTopeliuksenkatu 500260HelsinkiFinland