1,721,214 research outputs found
Effect of four higly bioaccumulated polychlorinated biphenyls (PCBs) alone and in mixture in MCF-7 breast carcinoma cell line
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Structural diagnosis of perfluorinated polymers for advanced applications: the joint use of vibrational spectroscopy and first-principles calculations
No full textExperimental IR spectra of perfluoropolyethers show many features which cannot be interpreted by means of simple correlations commonly used for band assignments. First-principles calculations on suitable molecular model should be used to this aim and reveal the existence of peculiar intra and intermolecular interactions which are responsible for the modulation of both the structural and spectroscopic properties of these polymers
Vibrational spectra and quantum chemical calculations of some polyfluoroethers
No full textVibrational spectroscopy and Density Functional Theory (DFT) quantum chemical calculations, have been used to investigate structure and chemical properties of some fluorinated ethers. A good agreement between experimental and theoretical results has been obtained. Interesting conformational behaviour has been observed and interpreted for C-H bonds in difluoromethyl end groups. These effects help in understanding the chemical behaviour of these compounds, since C-H equilibrium bond length and bond dissociation energy (BDE) can be correlated with vibrational properties. (C) 1998 Elsevier Science S.A. All rights reserved
Possible estrogenic effects of some higly bioaccumulated polychlorinated biphenyls (PCB101, 118,138,153) alone and in mixture in MCF-7 breast cancer cells
No full textPolychlorinated biphenyls (PCBs) are ubiquitous environmental persistent contaminants giving rise to potential health hazard. Depending on the position and number of chlorine substitutions, different classes of PCB congeners elicit a complex spectrum of biological and toxic responses in a number of models in vivo and in vitro. Moreover, some PCBs have been shown to have potential estrogen and anti-estrogen effects.
In the present study we have analysed the potential estrogenic effect in MCF-7 cells of four very biologically relevant PCB congeners alone and in mixture: PCB 101 (2,2′,4,5,5′-pentachlorobiphenyl), PCB 118 (2,3′,4,4′,5-pentachlorobiphenyl), PCB 138 (2,2′,4,4′,5,5′-hexachlorobiphenyl) and PCB 153 (2,2′,3,4′,5,5′-heptachlorobiphenyl).
The mixture of four PCBs was tested at seven different concentration chosen on the basis of their recovery from crop and some foods. The ability of these PCBs alone and in mixture to induce cell proliferation and the level of estrogen-regulated protein pS2 were studied using the human MCF-7 breast cancer cells.
In this cell line, only PCB 153 (35 μM) stimulates cell proliferation from 48 h up to 6th day, while PCB 118 (40 μM) only at 48 h. No effect was observed after treatment with PCB 101 (45 μM) and PCB 138 (10 μM) until 6 days. The treatment with different mixture concentrations causes a significant decrease of cell proliferation at different time. No variation of pS2 level was observed after treatment with the different PCBs alone and in mixture.
In exploring the molecular mechanism and the kinetic of these events, we found that PCB 153 was able to induced mitogen-activated protein kinase (MAPK) ERK1/2 at 4, 8 and 12 h, while the anti-proliferative effect seems to be mediated by an apoptotic action beginning at 12 and ending at 48 h
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