1. PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, Pharmaceutical Sciences Bonn (PSB), University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
2. Department of Molecular Pharmacology, RWTH Aachen University, Wendlingweg 2, D-52074 Aachen, Germany
3. MultiChannelSystems MCS GmbH, Aspenhausstrasse 21, D-72770 Reutlingen, Germany