1,721,078 research outputs found
Telomere loss, not average telomere length, confers radiosensitivity to TK6-irradiated cells
No full text""Many and varied are the proposed mechanisms that lead to resistance to ionizing radiation treatment. Among them, an inverse relationship between telomere length and radioresistance has been recently advanced. Investigating such a relationship in TK6 lymphoblasts, we found that clones originating from cells survived to 4Gy of X-rays showed a significantly higher telomere length when compared with clones grown from untreated cells. The lengthening observed was not attributable to a radiation-induced increase in telomerase activity, as demonstrated by TRAP assay performed in the dose range of 1-10Gy. Given the evidence that TK6 whole population was characterized by heterogeneity in cellular mean telomere length and telomere loss, we tested the hypothesis that a process of selection may favour cells with longer telomeres (more radioresistant cells) following exposure to irradiation. In order to do this 15 independent TK6 clones were selected and characterized for telomere length and loss on the basis of q-FISH and flow-FISH analysis. Among the screened clones four characterized by long telomeres and four characterized by short telomeres were tested for their radiosensitivity by means of clonogenic assay. The results obtained showed that, in our experimental conditions (cellular model, radiation doses) no significant correlation was observed between radiosensitivity and mean telomere lengths, whereas a positive correlation was observed with respect to telomere loss. Overall, these results indicate that telomere loss and not mean telomere length plays a critical role in the phenomenon of radiosensitivity\\\/radioresistance."
Comparison between two FISH techniques in the in vitro study of cytogenetic markers for low-dose X-ray exposure in human primary fibroblasts.
No full textCell cycle perturbations and cytogenetic damage induced by low energy protons in human primary fibroblasts
No full textChromosomal sensitivity to clastogenic agents and cell cycle perturbations in Nijmegen breakage syndrome lymphoblastoid cell lines
No full text: The relationship between chromosomal breakage and perturbations of cell cycle progression was investigated in lymphoblastoid cell lines established from a healthy donor, two subjects affected by Nijmegen Breakage Syndrome (NBS) and an ataxia-telangiectasia (AT) patient. The cytogenetic analysis revealed a similar chromosomal hypersensitivity in both NBS and AT cells exposed in the G1 phase to 200 cGy X-rays or in G2 to 15-30 cGy. Similarly, no differences were observed in the frequency of chromatid-type aberrations induced in G2 by 1-2 pg/ml calicheamicin gamma 1I, a DNA double-strand break inducer. In addition, as observed in AT cells, the rate of G2 radiation-induced chromosomal damage was less enhanced in NBS than in control cells following 3-h incubation with inhibitors of DNA synthesis/repair (cytosine arabinoside, aphidicolin, DMSO, hydroxyurea, caffeine). This is suggestive of an altered DNA lesion-processing pathway common to both syndromes. Despite the close resemblance of cellular phenotypes in the two syndromes, the analysis of mitotic indices carried out at 2 and 4 h postirradiation indicated that NBS sustained a G2-delay greater than that observed in AT cells, Furthermore, the flow cytometric analysis of 50-300 cGy irradiated cells at 10 and 20 h before harvesting showed that NBS cells sustained a G2/M phase arrest markedly lower than AT cells. Our data indicate that NBS and AT gene products are involved in a common pathway of radiation-induced chromosomal damage, but in a different one for cell cycle control after irradiation
Lack of effect of inhibitors of DNA synthesis/repair on the ionizing radiation-induced chromosomal damage in G2 stage of ataxia telangiectasia cells.
No full textTopoisomerase II inhibition in mitosis produces numerical and structural chromosomal aberrations in human fibroblasts.
No full textCytokinesis-block micronucleus assay with kinetochore detection in colchicine-treated human fibroblasts.
No full textRole of Bim in apoptosis induced in H460 lung tumor cells by the spindle poison Combretastatin-A4
No full textThe yield of fission neutron-induced chromatid aberrations in G2-stage human lymphocytes: effect of caffeine, hydroxyurea and cytosine arabinoside post-irradiation
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