1. Department of Neurosurgery, The Walton Centre for Neurology and Neurosurgery, National Health Service Trust, Liverpool, England
2. Department of Neuropathology, The Walton Centre for Neurology and Neurosurgery, National Health Service Trust, Liverpool, England
3. International Agency for Research on Cancer, Lyon, France
4. Department of Neurological Science, University of Liverpool, Liverpool, England