Stereoisomeric flavor compounds part. LV: Stereodifferentiation of some chiral volatiles on heptakis(2,3-di-O-acetyl-6-O-tert-butyldimethylsilyl)-β-cyclodextrin

Heptakis(2,3-di-O-acetyl-6-O-tert-butyldimethylsilyl)-β-cyclo -dextrin proves to be a versatile chiral stationary phase for the direct differentiation of aroma-relevant enantiomers.     

Cadmium(II) specifically interacts with cellular signaling to induce proto-oncogenes c-fos and c-jun in rat PC12 cells

Cadmium(II) compounds are carcinogens but only weakly mutagens. Because Cd(II) at low micromolar concentrations stimulates cell growth and induces some proto-oncogenes with several mammalian cell lines, the stimulation of cell proliferation is discussed as a major mechanism of the carcinogenicity of this metal. In the present work, the induction of the cellular proto-oncogenes c-fos and c-jun by Cd(II) was studied in rat PC12 cells. Several cellular signal transduction elements were tested as mediators of the proto-oncogene induction by cadmium. Cd(II) does not evoke mobilization of free intracellular Ca²⁺ in PC12 cells, and there was no impairment of the effect of Cd(II) by inhibitors of protein kinase A or of MAPK kinase. However, bisindolylmaleimide I, a specific inhibitor of protein kinase C abolished the proto-oncogene induction by Cd(II). Hence, a critical role for protein kinase C in the mitogenic effect of Cd(II) is inferred, and a substitution of structural Zn²⁺ ions by Cd²⁺ ions in this enzyme is discussed as the putative mechanism. Received: 30 July 1997 / Revised: 9 October 1997 / Accepted: 11 October 1997