1. Department of Neuropathology, University of Bonn Medical Center, Sigmund-Freud-Straße 25, 53105 Bonn, Germany.
2. Laboratory of Molecular Biology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892–4092, USA.
3. Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, USA.