1. Rudolf Virchow Center for Experimental Biomedicine; University of Würzburg, Josef-Schneider-Str.2; Würzburg 97080 Germany
2. Department of Toxicology; University of Würzburg, Versbacher Str. 9; Würzburg 97078 Germany
3. Bavarian Health and Food Safety Authority, Eggenreuther Weg 43; Erlangen 91058 Germany
4. Clinic and Policlinic of Nuclear Medicine; University of Wuerzburg, Oberduerrbacher Strasse 6; Würzburg D-97080 Germany