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Acesso aberto (Open Access)
Avaliação do efeito protetor da prolactina em linfócitos expostos a ação do metilmercúrio
(Universidade Federal do Pará, 2012-05-23) JESUS, Maria Izabel de; DINIZ, Domingos Luiz Wanderley Picanço; http://lattes.cnpq.br/9601463988942971
Mercury can be found in several forms, as being organic methylmercury (MeHg), considered the most toxic. Readily absorbed orally, accumulates in the food chain and is amplified in aquatic carnivores, especially in fish, hence the greater risk to populations that preferentially feed on them, such as riparian Amazonian populations. The neurotoxic effect of this form of mercury has been widely demonstrated by epidemiological and experimental studies. Some of these studies have also shown that hormones and antioxidants may act by protecting the body against the deleterious effects of mercury. Prolactin is a hormone that has such protective action, but also acts as a proinflammatory cytokine. Since MeHg can also act as an immunotoxic substance, we have studied the cytoprotective action of PRL in continuous cultures of strain B95-A primate lymphocytes in order to assess their vulnerability to MeHg and its responsiveness to the action of PRL. In order to assess the functional integrity of lymphocytes exposed to MeHg we used to test color reaction for 3 - (4,5-dimethylthiazol-2-yl) -2,5-diphenyl tetrazolium bromide (MTT), which detects activity mitochondrial metabolism. To evaluate the immune response of lymphocytes, measures of tumor necrosis factor alpha (TNF α) concentration in the middle were performed by ELISA. It is a proinflammatory cytokine released in response to cellular injury from different causes, including oxidative stress, one of the most obvious acute effects of MeHg, and this cytokine also be able to answer prolactin regulation in human lymphocytes. After 18 hours of cultivation exposure to increasing concentrations of the metal (0.1, 1, 5, 10 and 50 mM) showed significant decrease in dose-dependent cell viability from 1 mM (35%) and progressively up to 50 mM (80%), when few intact cells were found in the cultivation. A biphasic effect in a "bell" shaped occurred in the release of TNF-α, where lower concentrations of MeHg inhibited (0.1 and 1 mM) stimulated the intermediate (5 mM) and the two largest (10 and 50 mM) returned to inhibit. Prolactin also decreased the cell viability by about 30% only at the highest dose (10 nM).Moreover, at a dose of 1 nM prevented PRL 40% decrease in cell viability due to exposure to 5 mM MeHg. This dose of 1 nM PRL was the only one to stimulate the release of TNF-α, but curiously reversed the release of this cytokine when combined with 5 mM of MeHg, concentrations that also stimulated the secretion of TNF-α. The results confirmed the toxicity of MeHg to lymphocytes of primates (strain B95-A) and its reversion by possible protective action of PRL. A biphasic effect on the secretion of TNF α resulted from MeHg exposure, suggesting the presence of different mechanisms of cytotoxic action resulting from mercury. Moreover, PRL was less effective in stimulating the secretion of that cytokine, reversing this response when the associated with MeHg. However, these results are preliminary and require a more accurater study for their complete elucidation.
Acesso aberto (Open Access)
Níveis de TNF-α e seu polimorfismo genético em pacientes HIV positivos, portadores de lipodistrofia e em uso de terapia anti-retroviral
(Universidade Federal do Pará, 2008) PINHEIRO, Miguel Corrêa; LIBONATI, Rosana Maria Feio; http://lattes.cnpq.br/3818175484709618
This work presents the results of the research entitled Levels of TNF-α and its Genetic Polimorfism in Patient Positive HIV, Bearers of Lipodistrophy and in Use of Anti-retroviral Therapy. It was aimed at, through the research for now presented, to study the levels serics of TNF-α and its Genetic Polymorphism in Patient Positive HIV, Bearers of lipodistrophy and in Use of Anti-retroviral Therapy. The need of know better the factors involved in the development of a syndrome clinic known as lipodistrophy justifies that aims, considered an adverse effect of the anti-retroviral therapy, so that that knowledge oportunize the reliable of a safe therapeutic regime, propitiating, in that way, a possible improvement in the quality of the patients' life. The methodology undertaken for the quantitative determination of the serics levels of TNF-α it was used of the ELISA method, while, tends in view the research of the occurrence of the polymorphism, it was used of the reaction of PCR for the extraction of DNA, followed by the digestion for the restriction enzyme Ncol. Forty patients participated of the present researches, which 26 were male and 14 were female. In this patient, the dosing of the TNF-α levels was proceeded, as well as it researches of the presence or absence of the genetic polymorphism (-308A).