Brazil nut improves the oxidative metabolism of superoxide-hydrogen peroxide chemically-imbalanced human fibroblasts in a nutrigenomic manner.

There are some genes associated to the risk of chronic diseases that present potential nutrigenetic response, such as the human manganese-dependent superoxide dismutase gene (Val16Ala-SOD2, rs4880) for which homozygous genotypes (VV and AA) are associated with higher basal superoxide (S) and hydrogen peroxide (HP) levels, respectively. It is possible that the VV- and AA-imbalance could be attenuated by selenium(Se)-rich foods such as Brazil nut (BN). To test this hypothesis, we conducted an in vitro protocol triggering a chemical S-HP imbalance by exposure of dermal fibroblast cells (HFF-1) to paraquat, which generates high S levels (VV-like treatment) and porphyrin (MnTBAP), which generates high HP levels (AA-like treatment). Modulation of cell growth and pro-oxidative and antioxidant markers were evaluated. BN aqueous extract (BNAE) most effective concentration which increased cell growth and decreased oxidative metabolism indicators of imbalanced cells was 75 ng Se/mL. However, this effect was not directly affected by the S-HP imbalance: in AA-SOD2-like cells, thioredoxin reductase (TrxR-1) gene was upregulated and in VV-SOD2-like cells an upregulation of glutathione peroxidase (GPx-1) gene expression was observed, however, this regulation occured in a homeostatic manner. These results suggest that BNAE was able to minimize negative effects in both directions of the S-HP imbalance, by modulation of different oxidative-metabolic pathways.

Superoxide-hydrogen peroxide genetic imbalance modulates differentially the oxidative metabolism on human peripheral blood mononuclear cells exposed to seleno-L-methionine.

Superoxide-hydrogen peroxide (S-HP) imbalance genetically caused by a gene polymorphism in the human manganese superoxide dismutase enzyme (Val16Ala-MnSOD) is associated with several diseases. Into mitochondria, MnSOD catalyses superoxide radical producing HP and oxygen. Ala-MnSOD genotype presents a high MnSOD efficiency and generates the highest HP concentrations that has been associated with the risk of several cancer types. Cellular selenoenzymes glutathione peroxidase and thioredoxin reductase (TrxR) and catalase (CAT) are essential to HP removal produced in excess in cells. Since, synthesis and activities of selenoenzymes are selenium dependent, we hypothesized that AA-MnSOD cells could have an improvement on antioxidant status undergoing Seleno-L-methionine (SeMet) treatment. This study performed an in vitro protocol to evaluate the response of peripheral blood mononuclear cells (PBMC) carriers of different Val16Ala-MnSOD genotypes exposed to SeMet. SeMet effects on cell viability, apoptosis induction and modulation of oxidative variables were determined using spectrophotometric, flow cytometry, fluorimetric and immunoassays. Gene modulation of antioxidant enzymes was also performed by qRT-PCR. From an initial protocol using heterozygous (AV) cells was determined that 1nM SeMet presented a cytoprotective effect. However, whereas this concentration did not change AA viability, in VV cells it was cytotoxic by increasing necrosis events. SeMet induced higher selenoenzymes levels in AA and VV cells and decreased oxidative markers levels including DNA damage. The results suggest a pharmacogenetic positive response of SeMet effect on AA-cells. Future studies in vivo could be essential to evaluate the potential clinical impact of S-HP imbalance after use of foods or supplements containing SeMet.

Cytotoxic effects of moderate static magnetic field exposure on human periphery blood mononuclear cells are influenced by Val16Ala-MnSOD gene polymorphism.

Technological advancement has increasingly exposed humans to magnetic fields (MFs). However, more insights are necessary into the potential toxicity of MF exposure as a result of genetic variations related to oxidative metabolism. Therefore, the following study has assessed an in vitro cytotoxic effect of static magnetic field (SMF) (5 mT) on cells with Val16Ala polymorphism (AA, VA, and VV) in the manganese superoxide dismutase gene. Homozygous Val16Ala-superoxide dismutase 2 (SOD2) genotypes present oxidative imbalance that is associated with risk to several chronic degenerative diseases (VV produces less efficient and AA more efficient SOD2 enzyme). Blood samples from healthy adult subject carriers with different Val16Ala-SOD2 genotypes were obtained and exposed to MF at different times (0, 1, 3, 6 h). The cytotoxic effect as well as oxidative stress was evaluated after incubation of 24 h at 37 °C. In addition, apoptosis induction has been analyzed by flow cytometry as well as Bcl-2-associated X protein (BAX), B-cell lymphoma 2 (BCL-2), and caspases 8 and 3 gene expression. SMF cytotoxic effect has been observed in AA cells at all times of exposure, whereas AV cells presented higher mortality only after 6 h of exposure at SMF. Higher apoptosis induction has been observed in AA cells when compared to VV and AV cells. These results suggest a toxicogenetic SMF effect related to an imbalance in SOD2 activity.

Oxidative Profile of Patients with ST Segment Elevation Myocardial Infarction.

BACKGROUND: Patients with ST-segment elevation (STEMI) have totally occluded vessels, while patients with non-ST-segment elevation (NSTEMI) present partial vessel occlusion, which may generate different levels of Reactive Oxygen Species (ROS). Objectives: The aim of this study was to compare the oxidative profile in AMI patients with ST segment elevation and non-STEMI as well as control subjects. METHODS: This study was carried with 46 AMI patients divided into STEMI and NSTEMI. The control group consisted of 40 healthy subjects. Oxidative stress profile was evaluated analyzing carbonyl protein (PCO), lipid peroxidation (TBARS), ischemia-modified albumin (IMA), vitamin C (VIT C), superoxide dismutase (SOD) and catalase (CAT). RESULTS: Serum PCO (p < 0.001), plasma TBARS (p < 0.01), serum IMA (p < 0.0001) levels, erythrocytes CAT (p < 0.001), and SOD activities (p < 0.05) were significantly higher in STEMI patients when compared with the control group (p < 0.001). No difference in the IMA levels and oxidative stress parameters was observed between conditions of AMI. Only plasma VIT C in STEMI patients was significantly lower when compared with NSTEMI patients and control group (p < 0.001). CONCLUSIONS: Results suggest that the oxidative profile generated by STEMI and NSTEMI is similar regardless of the size of arterial occlusion generated by thrombus.

Methotrexate-related response on human peripheral blood mononuclear cells may be modulated by the Ala16Val-SOD2 gene polymorphism.

Methotrexate (MTX) is a folic acid antagonist used in high doses as an anti-cancer treatment and in low doses for the treatment of some autoimmune diseases. MTX use has been linked to oxidative imbalance, which may cause multi-organ toxicities that can be attenuated by antioxidant supplementation. Despite the oxidative effect of MTX, the influence of antioxidant gene polymorphisms on MTX toxicity is not well studied. Therefore, we analyzed here whether a genetic imbalance of the manganese-dependent superoxide dismutase (SOD2) gene could have some impact on the MTX cytotoxic response. An in vitro study using human peripheral blood mononuclear cells (PBMCs) obtained from carriers with different Ala16Val-SOD2 genotypes (AA, VV and AV) was carried out, and the effect on cell viability and proliferation was analyzed, as well as the effect on oxidative, inflammatory and apoptotic markers. AA-PBMCs that present higher SOD2 efficiencies were more resistance to high MTX doses (10 and 100 µM) than were the VV and AV genotypes. Both lipoperoxidation and ROS levels increased significantly in PBMCs exposed to MTX independent of Ala16Val-SOD2 genotypes, whereas increased protein carbonylation was observed only in PBMCs from V allele carriers. The AA-PBMCs exposed to MTX showed decreasing SOD2 activity, but a concomitant up regulation of the SOD2 gene was observed. A significant increase in glutathione peroxidase (GPX) levels was observed in all PBMCs exposed to MTX. However, this effect was more intense in AA-PBMCs. Caspase-8 and -3 levels were increased in cells exposed to MTX, but the modulation of these genes, as well as that of the Bax and Bcl-2 genes involved in the apoptosis pathway, presented a modulation that was dependent on the SOD2 genotype. MTX at a concentration of 10 µM also increased inflammatory cytokines (IL-1ß, IL-6, TNFα and Igγ) and decreased the level of IL-10 anti-inflammatory cytokine, independent of SOD2 genetic background. The results suggest that potential pharmacogenetic effect on the cytotoxic response to MTX due differential redox status of cells carriers different SOD2 genotypes.

Aspectos gerais e diagnóstico clinicolaboratorial da intoxicação por paraquat / General aspects and clinical laboratorial diagnostic of poisoning by paraquat

INTRODUÇÃO: O paraquat, herbicida amplamente utilizado na agricultura, é um produto perigoso, pois pode causar intoxicações fatais, principalmente pela falta de antídoto eficaz para reversão do quadro clínico. Fisiopatologia: Os efeitos toxicológicos são decorrentes da indução ao estresse oxidativo. O órgão-alvo principal é o pulmão, que pode apresentar edema, hemorragia, inflamação intersticial e fibrose, culminando com falência respiratória grave e morte. Além disso, é nefrotóxico, hepatotóxico, miotóxico e neurotóxico. TRATAMENTO: Além de visar a diminuição da absorção e estimular a excreção do paraquat absorvido, o tratamento da intoxicação atualmente é baseado em medidas que diminuam o estresse oxidativo utilizando substâncias antioxidantes e, conseqüentemente, revertam o quadro toxicológico instalado, especialmente o pulmonar. MÉTODOS DIAGNOSTICOS: Entre as metodologias quantitativas disponíveis, os métodos cromatográficos são os mais relatados para materiais biológicos. Porém, a eletroforese capilar e os imunoensaios podem ser utilizados. Os imunoensaios destacam-se pela praticidade laboratorial, pois os cromatográficos e eletroforéticos não são encontrados comumente em laboratórios hospitalares. Por outro lado, uma reação simples e rápida de caracterização urinária com ditionito de sódio é muito realizada, pois é preditiva na suspeita de intoxicações agudas. CONCLUSÃO: Diante do alto potencial de morbimortalidade nas intoxicações por paraquat, a reversão dos danos pulmonares com uso de antioxidantes vem sendo muito estudada, porém não há o estabelecimento de um antídoto específico. No diagnóstico laboratorial, métodos cromatográficos, eletroforéticos e imunológicos são usados para quantificá-lo, contudo a reação urinária com ditionito ainda é valiosa na rotina da toxicologia clínica.

INTRODUCTION: Paraquat is a herbicide widely used in agriculture. It is a very toxic product, fatally poisoning mainly by the lack of an efficient antidote to revert the clinical state. FISIOPATHOLOGY: Toxicological effects are decurrent of oxidative stress. The most important target organ is the lung, which can display edema, hemorrhage, interstitial inflammation and fibroses, culminating in serious respiratory failure and death. Moreover, it is nephrotoxic, hepatotoxic, miotoxic and neurotoxic. TREATMENT: Besides aiming the decrease of absorption and stimulating the excretion of absorbed paraquat, the poisoning treatment nowadays is based on measures that decrease oxidative stress using antioxidants, consequently reverting clinical state, mainly the pulmonary. Diagnostic methods: Among the available quantitative methods, the chromatographic are the most reported ones for biological samples. However, capillary electrophoresis and immunoassay methods can be used. Immunoassays stand out for being typically found in hospital laboratories, while chromatographic and electrophoretic methods are not. On the other hand, a simple and fast urinary reaction with sodium dithionite is very utilized because it is predictive in acute poisoning suspect. CONCLUSION: In the presence of high morbimortality potential in paraquat intoxications, the reversion of pulmonary toxicity with antioxidants is extensively studied, but a specific antidote is not established. In laboratorial diagnostic, chromatographic, electrophoretic and immunologic techniques are applied to paraquat quantification, although in clinical toxicology the sodium dithionite reaction is still significant.

Fisiopatologia da deficiência de vitamina B12 e seu diagnóstico laboratorial / Physiopathology of vitamin B12 deficiency and its laboratorial diagnosis

INTRODUÇAO: A vitamina B12 é hidrossolúvel, não-sintetizada pelo organismo humano, presente em alimentos de origem animal. Sua deficiência é muito freqüente entre idosos, vegetarianos e indivíduos que adotam baixa dieta protéica ou apresentam problemas de absorção gastrintestinal. FISIOPATOLOGIA: A deficiência de vitamina B12 leva a transtornos hematológicos, neurológicos e cardiovasculares, principalmente, por interferir no metabolismo da homocisteína (Hcy) e nas reações de metilação do organismo. Muitas vezes a deficiência pode permanecer assintomática por longos períodos, desencadeando uma deficiência crônica que, se mantida, pode levar a manifestações neurológicas irreversíveis. METODOLOGIAS: Metodologias eficientes que permitam um diagnóstico precoce são imprescindíveis. Porém um método considerado padrão-ouro ainda não é consensual. A dosagem sérica de vitamina B12 sofre algumas restrições pelos problemas de sensibilidade e especificidade, podendo ocorrer sintomas de deficiência mesmo com vitamina B12 sérica dentro dos níveis normais ou, de outro modo, ocorrendo baixos níveis de vitamina B12 sérica sem, contudo, apresentar baixos níveis da fração de vitamina realmente disponível para as células e sem apresentar sintomatologia. Novas alternativas vêm surgindo, como a dosagem de transcobalamina II (Tc II), a única fração de vitamina B12 disponível para as células, ou a dosagem de ácido metilmalônico (MMA) e Hcy, metabólitos que aumentam quando ocorre diminuição de vitamina B12 intracelular. Estes testes apresentam algumas vantagens, mas também limitações importantes para uso rotineiro. CONCLUSAO: Em casos subclínicos, um diagnóstico correto e precoce representa ainda um desafio, e futuros estudos são necessários para definir um método padrão para diagnóstico laboratorial da deficiência de vitamina B12.

Ciclosporina A e tacrolimus: uma revisão / Cyclosporine A and tacrolimus: a review

INTRODUÇAO: Monitorização terapêutica de imunossupressores ciclosporina A (CsA) e tacrolimus (FK506) é indispensável para manter níveis estáveis das drogas, evitando para o transplantado a perda do enxerto, no caso de baixas doses, ou a toxicidade, em altas doses, permitindo ajustes individuais. HISTORICO: Na década de 80, foi introduzida a utilização dos potentes imunossupressores CsA e FK506, revolucionando o transplante de órgãos com a diminuição da rejeição. MECANISMO DE AÇAO: A CsA e o FK506 são inibidores da transcrição do primeiro sinal para ativação dos linfócitos T, apresentando estruturas químicas diferentes, mas mecanismos semelhantes. TOXICIDADE: Os principais efeitos relacionados à dose da CsA e do FK506 são a nefro e a neurotoxicidade. Estudos apontam o FK506 como droga alternativa à utilização da CsA porque aquele demonstrou menor nefrotoxicidade e uma reversibilidade dos efeitos neurotóxicos diante da redução da dose. METODOLOGIA ANALíTICA: Na monitorização de rotina para a CsA, os imunoensaios, radioimunoensaio (RIA) e imunoensaio monoclonal com fluorescência polarizada (FPIAm) ocuparam o lugar da cromatografia líquida de alta eficiência (CLAE), detecção ultravioleta (UV). O método de referência para o FK506 é a CLAE com detecção por espectrometria de massa (LC/MS). Porém, metodologias como ensaio imunoenzimático de micropartículas (MEIA) ou enzyme linked imunosorbent assay (ELISA) têm sido utilizadas na rotina laboratorial. CONCLUSAO: Parece existir uma tendência para a substituição terapêutica da CsA pelo FK506 no tratamento imunossupressor, porém ainda não se estabeleceu consenso nessa conduta. A metodologia analítica para a análise da CsA encontra-se bem estabelecida; para o FK506, estudos ainda são necessários.