We have examined the biological activity of keto-C-glycosides (KCGs), a new family of drugs displaying anti-proliferative and cytotoxic properties on tumor cells. KCG1, the most powerful drug tested on epithelial derived neoplastic cells, was 25–125 times more cytostatic on epithelial cells than on lymphoma. By contrast, KCG10 proved to be more cytostatic on lymphoma than on epithelial cells. Correlations were found between the cytostaticity of KCGs and their lipophflicity, and are discussed within the framework of the structure-activity and the structure-selectivity relationships.
Α-Fetoprotein (AFP) and AFP-gene transcripts were demonstrated in vitro in Schwann (S) cell and fibroblast (F) cell cultures of neonatal mouse origin. All S and F cells of primary cultures and of established cell lines expressed the AFP gene. AFP mRNA was detected by an in situ hybridization technique using a 35S-AFP-cDNA probe. AFP was localized by immunocytoperoxidase labelling using purified anti-AFP antibodies. The amounts of stained endogenous AFP, estimated semiquantitatively, were about 3-fold higher in S cells than in F cells. After incubating the cultures with exogenous mouse AFP, both S and F cells showed significant ability to take up the protein; the amount of internalized protein was found to be higher in F cells than in S cells. Moreover, the uptake of AFP fluorescein conjugates (FITC-AFP), estimated quantitatively by fluorometry, also gave higher values for F cells. The cytoplasm of F cells exhibited a characteristic fluorescence pattern, strongly illuminated and dispersed grains; the cytoplasm of S cells was regularly labelled. If exogenous FITC-AFP uptake could be used to distinguish labelled F cells from S cells (with application for identification and selection of F cells), the immunocytochemically stained endogenous AFP could allow S cells to be distinguished from F cells (using the dilutions of antibodies still staining the S cells but which lead to the absence of F-cell labelling). The two procedures, which can be used independently or together, may constitute differential markers for S cell and F cultures in, i.e., nerve regeneration of neurofibroma studies using the model of mixed S and F culture also containing other types of cells.
The inhibitory effect of crude Fusarium poae extracts, T2-toxin and diacetoxyscirpenol on synthesis of antibody to sheep red blood cells was investigated, as well as the effect of T2-toxin on skin graft rejection. Fusarium crude extracts, T2-toxin and diacetoxyscirpenol cause a significant reduction in thymus weight and inhibit responsiveness to sheep red blood cells. The effect on antibody synthesis was critically dependent on the drug doses used. The effect of an immunosuppressive dose of T2-toxin disappeared within 6 days after the end of the treatment. The administration of T2-toxin subsequent to immunization stops antibody synthesis. T2-toxin significantly prolongs the period required for skin graft rejection.
Abstract The great sensitivity of some cell species to toxins has been adapted to a direct biological determination of trichothecene contamination of food and feeds. The murine spleen lymphocyte stimulated by PHA (Phaseolus vulgaris phytohaemagglutinin) appeared to be the most convenient cells because of their particular sensitivity to cytotoxic trichothecenes and the opportunity to translate this cytotoxicity to immunosuppressive hazard, one of the most important concerns for trichothecenes. In this paper, the use of cell cultures was adapted for a survey of corn. The toxins were extracted by aqueous methanol, and the extract was defatted with hexane and purified on a silica gel/ Florisil column. This extract was then used for a gas chromatographic (GC) determination and the biological test. The growth of cells was measured by the incorporation of tritiated thymidine (3H Tdr), and the inhibition was expressed by the IC^: concentration of corn extract inhibiting by half the 3H Tdr incorporation. We have tested pure toxins, control corn, corn spiked with T-2 toxin, corn experimentally inoculated with toxigenic Fusarium strains, and naturally contaminated corn. A good correlation exists between IC50 and the T-2 toxin concentration as determined by GC analysis. The response is not affected by the presence of zearalenone or by small amounts of deoxynivalenol. A quantitative evaluation of cytotoxic trichothecenes in corn is valuable in the range of 100 ppb to 10 ppm, expressed as T-2 toxin equivalents. The result is obtained in 48 h
