Research Laboratories of Bayer Schering Pharma AG, Berlin, Germany. groth@informatik.hu-berlin.de|Research Laboratories of Bayer Schering Pharma AG, Berlin, Germany. groth@informatik.hu-berlin.de|Research Laboratories of Bayer Schering Pharma AG, Berlin, Germany. groth@informatik.hu-berlin.de|Research Laboratories of Bayer Schering Pharma AG, Berlin, Germany. groth@informatik.hu-berlin.de