H. Marquardt, Department of Toxicology, Hamburg University Medical School, Kortenredder 3, 22397 Hamburg, Germany, Fax: +49 40 60558553
K. Wallace, Department of Biochemistry & Molecular Biology, Medical School Duluth, University of Minnesota Medical School, 1035 University Drive, Duluth, MN 55812, USA, Fax: +1 218 726 8014