1. Institute of Pharmacology and Toxicology, University of Bonn, 53105 Bonn, Germany.
2. Department of Molecular Medicine, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany.
3. Division of Neurochemistry, Department of Epileptology, University of Bonn, 53105 Bonn, Germany.
4. Pharma-Center, University of Bonn, 53105 Bonn, Germany.