Chronic low dose exposure to hydrogen peroxide changes sensitivity of V79 cells to different damaging agents

832-836<span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:hi"="" lang="EN-IN">Chinese hamster V79 cells were repeatedly exposed to a low dose of hydrogen peroxide (H2O2) over several weeks and then exposed to H2O2, cisplatin or ultraviolet (UV) light. Cell killing was examined by colony formation, following these treatments. It was seen that cells conditioned by multiple low doses of H2O2 showed resistance to killing in case of H2O2 and cisplatin but the sensitivity to UV light was same as the control cells. Apoptosis was also determined in these cells after the same treatments. UV light failed to induce apoptosis in both conditioned and in control cells, but in case of cells treated with H2O2and with cisplatin, there was less apoptosis in the conditioned cells compared to the control cells. From our observation we can say that the enhanced survival of cells after treatment with H2O2 or cisplatin could be due to inhibition of apoptosis.</span

Adverse and beneficial effects in Chinese hamster lung fibroblast cells following radiofrequency exposure

In this study, the effect of radiofrequency (RF) exposure to 1950MHz, Universal Mobile Telecommunication System signal, was investigated in Chinese hamster lung fibroblast cell line (V79). Genotoxic and cytotoxic effects of 20-h exposure at specific absorption rate (SAR) values from 0.15W/kg to 1.25W/kg were measured by means of cytokinesis-block micronucleus (MN) assay. Exposure was carried out blinded under strictly controlled conditions of dosimetry and temperature. The effect of RF exposure alone at four SAR values was tested, that is, 0.15, 0.3, 0.6, and 1.25W/kg. A statistically significant increase in MN frequency was found in cultures exposed to 0.15 and 0.3W/kg (P<0.05) compared to sham-exposed ones, in the absence of cytotoxicity. SAR values of 0.6 and 1.25W/kg did not exert any effect. Moreover, to evaluate the ability of RF to exert protective effects with respect to a chemical mutagen, cell cultures were also pre-exposed for 20h at 0.3 or 1.25W/kg, and then treated with 500ng/ml of mitomycin-C (MMC). A significant reduction in the frequency of MN was detected in cultures pre-exposed to 1.25W/kg compared to cultures treated with MMC alone (P<0.05), indicating induction of adaptive response. Such a decrease was not induced by pre-exposure at 0.3W/kg SAR. Taken together, our results indicated that V79 is a sensitive cell model to evidence either adverse or beneficial effects of RF exposure, depending on experimental conditions applie