Browsing by Author "Preeta, R"

Now showing 1 - 3 of 3
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    Stimulation of cardiac fibroblast proliferation by cerium: a superoxide anion-mediated response
    (JOURNAL OF MOLECULAR AND CELLULAR CARDIOLOGY, 1999)
    Cardiac fibroblasts play a multifarious role in the maintenance of the functional and structural integrity of the heart. Therefore inadvertent proliferation of these fibroblasts can affect the normal functioning of the heart. The proliferation of fibroblasts could be due to various factors. We have worked on the hypothesis that low levels of cerium may stimulate cardiac fibroblasts to undergo proliferation and that free radicals act as the mediators of the stimulatory response. Cardiac fibroblasts isolated from neonatal Wistar rats were cultured. Proliferation of the cells was measured by cell count and immunohistochemical visualization for proliferating cell nuclear antigen, The response to cerium was assessed by comparison with control. A stimulatory response at low levels of cerium was observed with a peak at 0.5 mu M concentration of cerium. A concomitant increase in the generation of free radicals was also seen. The cerium-stimulated cell proliferation and free radical generation was neutralized by the inclusion of superoxide dismutase in the culture medium.Conclusion: Low doses of cerium, at levels comparable to those found in the serum of patients with EMF, has a stimulatory effect on cardiac fibroblasts and the abrogation of proliferation by antioxidant superoxide dismutase indicates that superoxide anion acts as a biological intermediate in cerium-induced cardiac fibroblast proliferation. (C) 1999 Academic Press.
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    Superoxide anions mediate proliferative response in cardiac fibroblasts
    (INDIAN JOURNAL OF MEDICAL RESEARCH, 2000) Preeta, R; Nair, RR
    The study was undertaken to examine whether superoxide anions mediate a proliferative response in cardiac fibroblasts. Cardiac fibroblasts isolated from newborn Wistar rats were exposed to superoxide anion generating system (hypoxanthine + xanthine oxidase) and its effect on cell growth was assessed. A stimulatory response on fibroblast proliferation was observed. The proportion of proliferating cells increased within 3 h of treatment compared to the control and the cell density after 96 h of exposure remained significantly high (P<0.0005). Inclusion of antioxidants neutralised the stimulatory response, fortifying the role of superoxide anions in cell proliferation. This observation indicates that superoxide anions can mediate a fibrotic reaction in the cardiac tissue.
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    Variation in mitogenic response of cardiac and pulmonary fibroblasts to cerium
    (BIOLOGICAL TRACE ELEMENT RESEARCH, 2003)
    Fibroproliferative response of rat heart and lung fibroblasts to the lanthanide cerium was examined, as the element has been implicated in the causation of cardiac and pulmonary fibrosis. Fibroblasts from both of the organs were morphologically identical, and the response to fetal bovine serum, a nonspecific mitogen, was also comparable. The oxygen radical generator (hypoxanthine + xanthine oxidase [Hyp. + XO]) induced a proliferative response that was neutralized in both cardiac and lung fibroblasts by free-radical scavengers. Superoxide dismutase was more effective than catalase in reducing the mitogenic effect of Hyp. + XO. The free-radical scavenger N-acetyl-L-cysteine neutralized the free-radical-mediated changes in pulmonary fibroblasts but had a negative effect in cardiac fibroblasts, indicating a tissue-dependent variation. Reactive oxygen species are known to act as biological mediators of tissue fibrosis induced by metallic compounds. Exposure to low levels of cerium (0.5 muM) stimulated a mitogenic response in cardiac fibroblasts, but the pulmonary fibroblasts were not sensitized by the element. Tissue-dependent variation in proliferative response to cerium shows a positive association with intracellular generation of reactive oxygen species. Fibrotic changes in cerium pneumoconiosis may either be replacement fibrosis following tissue damage or mediated by nonfibroblastic cells. The study confirms that cardiac and pulmonary fibroblasts are dissimilar cellular subtypes.