Plating densities, alpha-difluoromethylornithine effects and time dependence on the proliferation of IEC-6 cells

To characterize the role of plating densities and alpha difluoromethylornithine (DFMO) on the proliferation of IEC 6 cells in vitro Methods IEC 6 cells were seeded in 96 well microplates at various densities in the pre sence or absence of DFMO Cells were counted and their proliferative capabilit y was monitored Days 1 to 7 with MTT assay at an optical density of 570?nm Results There was a positive relationship between cell number and OD value ( r =0 954 , P 【0 01) Higher plating densities (】0 5×10 4 cells/well) inhibited the growth of cells on Day 2 When the density reaches 4×10 4 cells/well, the O D value increased gradually and reached a peak on Day 5 After that, the OD va lue began to fall The growth of IEC 6 cells was limited at a low density (0 2×10 4 cells/well) on Day 4 DFMO caused a complete inhibition of proliferati on of IEC 6 cells on Days 1 to 3 Conclusion Proliferation of IEC 6 cells is related to plating density and incubation time It is inhibited by DFMO, but is reversible when the incubation time is prolon ged

Effects of mosquito hemocytes on normal and degenerated oocysts of Plasmodium yoelii and their role in oocyst melanization

Anopheles stephenst, infected with Plasinodium yoelii, was fed with 10% sucrose solution contatning 1% difluoromethylornithine (DFMO) to induce oocyst degeneration of the malaria parasites. On the 11th day after infection, the effects of mosquito hemocytes On the normal and degenerated oocysts were observed under transmission electron microscope. In the control group, no hemocyte could be found around the normally-developed oocysts. In the DFMO-treated group, all the oocysts underwent degeneration in various degrees and some of them were melanized. All the oocysts were attached by one or more hemocytes of the kind of granulocytes.There were many granules with microtubular structure in the cytoplasm of the hemocytes and in the space between the hemocyte and the oocyst. The findings suggest that the degeneration of oocysts can attract the hemocytes to attach around them and the latter can release granules and possibly other substances to cause encapsulation and melanization of the oocvsts.

INHIBITORY EFFECT OF DEMO ON THE GROWTH OF TRANSPLANTED HUMAN COLON CANCER IN NUDE MICE

A human colon cancer cell line Hce- 8693 was heterotransplanted in nude mice. Polyamine blosythesis Inhibitor a- dlfiuoromethylomithine (DFMO ) show a marked reproducible inhibition in this model. The size and weight of transplanted tumor In DFMO group were smaller than those of the control group and the average inhibition rate was 72.8% (P < 0.001) . DFMO showed higher tumor inhibitory rate than 5-Fu (35. 4%) (P<0. 001) . Furthermore. DFMO demonstrated less severe bone marrow inhibition in the nude mice than 5-Fu (20. 0% Vs 53. 2%. P<0. 001) .There was no synergistic action in these two drugs at the experimental dose. The concentration of putrescine and spermidine in the plasma and tumor tissue in the DFMO group were 70% lower than those of the control group (P<0. 001) . These results indicate that the anti-tumor effect of DFMO might be explained by the inhibition of polyamine biosynthesis and this study provides an experimental basis for future clinical application of DFMO.