Showing papers by "Sharad Kumar published in 1987"
TL;DR: The activity of topoisomerase II was markedly reduced in two ataxia-telangiectasia cell lines, AT2ABR and AT8ABR, compared to controls, and may reflect to some extent the heterogeneity observed in this syndrome.
21 citations
TL;DR: It is demonstrated that histone mRNA synthesis is radioresistant in ataxia-telangiectasia cells and is coupled to radiorsistant DNA synthesis in these cells.
Abstract: Cloned genomic DNA for human histone H1, H3 and H4 genes has been used to determine the effects of γ-radiation on histone mRNA levels and synthesis in ataxia-telangiectasia cells. Synthesis of histone mRNA was determined in cells synchronized with aphidicolin. Effects of irradiation on DNA synthesis and passage through S phase were also monitored. Irradiation was found to slow the passage of control cells through the cell cycle but had no effect on progression of ataxia-telangiectasia cells. H1 and core histone mRNA synthesis was inhibited by radiation in two control cell lines after release from aphidicolin block. No inhibition was observed in one ataxia-telangiectasia cell line and a small degree of inhibition in a second. An increased level of mRNA was observed in both irradiated control and ataxia-telangiectasia cells at 5–7 h post-irradiation compared to unirradiated cells. Similar results were obtained in log phase cells. These results demonstrate that histone mRNA synthesis is radioresistant in ataxia-telangiectasia cells and is coupled to radioresistant DNA synthesis in these cells.
6 citations