NADPH is the reducing agent for mitochondrial H2O2 detoxification systems. Nicotinamide nucleotide transhydrogenase (NNT), an integral protein located in the inner mitochondrial membrane, contributes to an elevated mitochondrial NADPH/NADP(+) ratio. This enzyme catalyzes the reduction of NADP(+) at the expense of NADH oxidation and H(+) reentry to the mitochondrial matrix. A spontaneous Nnt mutation in C57BL/6J (B6J-Nnt(MUT)) mice arose nearly 3 decades ago but was only discovered in 2005. Here, we characterize the consequences of the Nnt mutation on the mitochondrial redox functions of B6J-Nnt(MUT) mice. Liver mitochondria were isolated both from an Nnt wild-type C57BL/6 substrain (B6JUnib-Nnt(W)) and from B6J-Nnt(MUT) mice. The functional evaluation of respiring mitochondria revealed major redox alterations in B6J-Nnt(MUT) mice, including an absence of transhydrogenation between NAD and NADP, higher rates of H2O2 release, the spontaneous oxidation of NADPH, the poor ability to metabolize organic peroxide, and a higher susceptibility to undergo Ca(2+)-induced mitochondrial permeability transition. In addition, the mitochondria of B6J-Nnt(MUT) mice exhibited increased oxidized/reduced glutathione ratios as compared to B6JUnib-Nnt(W) mice. Nonetheless, the maximal activity of NADP-dependent isocitrate dehydrogenase, which is a coexisting source of mitochondrial NADPH, was similar between both groups. Altogether, our data suggest that NNT functions as a high-capacity source of mitochondrial NADPH and that its functional loss due to the Nnt mutation results in mitochondrial redox abnormalities, most notably a poor ability to sustain NADP and glutathione in their reduced states. In light of these alterations, the potential drawbacks of using B6J-Nnt(MUT) mice in biomedical research should not be overlooked.

Mitochondrial redox imbalance has been implicated in mechanisms of aging, various degenerative diseases and drug-induced toxicity. Statins are safe and well-tolerated therapeutic drugs that occasionally induce myotoxicity such as myopathy and rhabdomyolysis. Previous studies indicate that myotoxicity caused by statins may be linked to impairment of mitochondrial functions. Here, we report that 1-h incubation of permeabilized rat soleus muscle fiber biopsies with increasing concentrations of simvastatin (1–40 μM) slowed the rates of ADP-or FCCP-stimulated respiration supported by glutamate/malate in a dose-dependent manner, but caused no changes in resting respiration rates. Simvastatin (1 μM) also inhibited the ADP-stimulated mitochondrial respiration supported by succinate by 24% but not by TMPD/ascorbate. Compatible with inhibition of respiration, 1 μM simvastatin stimulated lactate release from soleus muscle samples by 26%. Co-incubation of muscle samples with 1 mM L-carnitine, 100 μM mevalonate or 10 μM coenzyme Q10 (Co-Q10) abolished simvastatin effects on both mitochondrial glutamate/malate-supported respiration and lactate release. Simvastatin (1 μM) also caused a 2-fold increase in the rate of hydrogen peroxide generation and a decrease in Co-Q10 content by 44%. Mevalonate, Co-Q10 or L-carnitine protected against stimulation of hydrogen peroxide generation but only mevalonate prevented the decrease in Co-Q10 content. Thus, independently of Co-Q10 levels, L-carnitine prevented the toxic effects of simvastatin. This suggests that mitochondrial respiratory dysfunction induced by simvastatin, is associated with increased generation of superoxide, at the levels of complexes-I and II of the respiratory chain. In all cases the damage to these complexes, presumably at the level of 4Fe-4S clusters, is prevented by L-carnitine.

Tumor necrosis factor alpha release in peripheral blood mononuclear cells of cutaneous lupus and dermatomyositis patients. Arthritis Res Ther 2012;14(1):R1.

Photodynamic therapy (PDT) appears as a promising alternative in the treatment of breast cancer since it can be highly effective in curing cancer while preserving normal tissue. However, predicting outcomes in PDT still constitutes a great challenge. One of the parameters that are usually empirically determined is the rate of photon flux delivered to the tissue (light fluence rate). In the present study, we intended to understand why monolayers of human cells derived from mammary adenocarcinomas (MDA‐MB‐231 and MCF‐7) respond quite differently to fluence rates (cells were irradiated either for 6 or for 16 min) at a fixed light dose (4.5 J cm−2) delivered with an array of LEDs in a typical methylene blue PDT protocol. While death rates of MDA‐MB‐231 cells were insensitive to the fluence rate, MCF‐7 cells showed a quite impressive (three times) decrease in cell death levels in the shorter irradiation protocol. Independent on cell type cell death was invariably correlated with the depletion of reduced glutathione intracellular levels and consequently with widespread redox misbalance. Our data show the potential to optimize fluence rates to provide exhaustion of the cell antioxidant responses in order to circumvent therapy resistance of breast tumors.

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RESUMO -Desde os primórdios o homem buscou selecionar as plantas alimentícias para maior produtividade. O conhecimento da estrutura do DNA permitiu que a engenharia genética se desenvolvesse consideravelmente fornecendo ferramentas para a realização de alterações específicas no genoma. Os produtos destas alterações são denominados transgênicos ou organismos geneticamente modificados (OGM) e apresentam alto potencial de aplicação em diversas áreas da atividade humana como: agricultura, medicina, saúde, produção e processamento de alimentos, produção bioquímica, controle de doenças e biorremediação. Atualmente, as plantas transgênicas, oriundas da tecnologia do DNA recombinante, trouxeram novas variedades já cultivadas em mais de 100 milhões de hectares em 23 países, incluindo o Brasil, onde 8 variedades já foram aprovadas pela Comissão Técnica Nacional de Biossegurança (CTNBio). Esse método de melhoramento genético facilitou a introdução de características desejáveis em plantas, como resistência a estresses bióticos e abióticos e otimização da composição de alguns nutrientes essenciais à saúde animal e humana. Enquanto estes avanços da biotecnologia abrem novas perspectivas para a solução de problemas em áreas como a agricultura, a liberação de transgênicos para uso na natureza traz preocupações quanto a possíveis problemas de natureza ecológica e para a saúde humana e animal. Estas preocupações deram origem à criação de agências governamentais para controlar o uso desta tecnologia e regulamentar a segurança dos alimentos transgênicos e seus derivados. Até o momento, os estudos científicos mostram que os transgênicos liberados comercialmente são tão seguros ou mais ao meio ambiente e a saúde animal e humana que os convencionais.Palavras-chave: organismos geneticamente modificados, saúde humana e animal, segurança alimentar, transgênicos em rações Use of ingredients from OGM in feed and its impact on the production of food of animal origin for humanABSTRACT -From the origins the man has looked and selected vegetables with nutritive value for larger productivity. The knowledge of DNA structure allowed genetic engineering to develop and supplying tools for the accomplishment of specific alterations in the genome considerably. The products of these alterations are denominated transgenic or organisms genetically modified (OGM) and they present high application potential in several areas of the human activity as: agriculture, medicine, health, production and processing of foods, biochemical production and control of diseases. Nowadays, transgenic plants, originating from technology of the DNA recombinant, brought new varieties cultivated already in more than 100 million hectares in 23 countries, including Brazil, where 8 varieties were already approved for the National Technical Commission of Biosafety (CTNBio). That method of genetic improvement facilitated the introduction of desirable characteristics in plants, such as, resistance to biotic and non-biotic stress and optimization of the composition of some essential ...

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In addition to be the cell's powerhouse, mitochondria also contain a cell death machinery that includes highly regulated processes such as the membrane permeability transition pore (PTP) and reactive oxygen species (ROS) production. In this context, the results presented here provide evidence that liver mitochondria isolated from Gracilinanus microtarsus, a small and short life span (one year) marsupial, when compared to mice, are much more susceptible to PTP opening in association with a poor NADPH dependent antioxidant capacity. Liver mitochondria isolated from the marsupial are well coupled and take up Ca2+ but exhibited a much lower Ca2+ retention capacity than mouse mitochondria. Although the known PTP inhibitors cyclosporin A, ADP, and ATP significantly increased the marsupial mitochondria capacity to retain Ca2+, their effects were much larger in mice than in marsupial mitochondria. Both fluorescence and HPLC analysis of mitochondrial nicotinamide nucleotides showed that both content and state of reduction (mainly of NADPH) were lower in the marsupial mitochondria than in mice mitochondria despite the similarity in the activity of the glutathione peroxidase/reductase system. Overall, these data suggest that PTP opening is an important event in processes of Ca2+ signalling to cell death mediated by mitochondrial redox imbalance in G. microtarsus.