Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.6.99.3 (diaphorase)
 5,903 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Midazolam, a water soluble benzodiazepine used as a preanaesthetic and hypnotic drug, showed a concentration-related (0.1-0.75 mM) depressant effect on both Adenosine 5'-diphosphate (ADP)-induced oxygen consumption and oxidative phosphorylation of rat liver mitochondria if the substrate was oxidized at different steps in the oxidation chain, but not when the substrate was ascorbate plus tetramethyl-p-phenylenediamine (complex IV). Furthermore, midazolam did not affect citrate synthase activity, but inhibited the 2,4 dinitrophenol (DNP)-uncoupled mitochondrial respiration. This result shows that midazolam primarily acts as a mitochondrial electron transport inhibitor. This inhibition is mainly due to the fact that midazolam decreases NADH ubiquinone reductase (complex I) and ubiquinol cytochrome c reductase (complex III) activities, but it also inhibits complex II activity. Spectrophotometric measurements of redox states of rat skeletal muscle mitochondria cytochromes show a decrease in the reduction of aa3 and c+c1 cytochromes in the presence of the benzodiazepine. Midazolam significantly decreased the reduced ubiquinone/total ubiquinone ratio (evaluated by means of HPLC and electrochemical detection) in rat liver mitochondria in both beta-hydroxybutyrate and succinate. Ubisemiquinone may be the redox component affected by midazolam, whether or not bound to the iron-sulfur proteins present in all three mitochondrial complexes. These effects of midazolam, not necessarily related to the preanaesthetic and hypnotic action are probably mediated via mitochondrial benzodiazepine receptors.
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PMID:Biochemical characterization of the effects of the benzodiazepine, midazolam, on mitochondrial electron transfer. 882 37

To better characterize the role of skeletal muscle in chronic heart failure we studied energetic charge, metabolites and enzyme activity in the energy production pathway. We selected 15 males with severe chronic heart failure (NYHA class III, stable clinical conditions and in normal nutritional status) and seven controls. Controls and patients were submitted to biopsy of the vastus lateralis muscle in resting and fasting conditions. Hormone profiles were also evaluated. Our results showed near normal ATP, ADP and AMP concentrations, but there were substantially more reductions in glycogen (46 +/- 5 vs 77 +/- 6 mumoles glycosidic units.g-1 fresh tissue) and creatine phosphate (5 +/- 1 vs 13 +/- 1 mumoles.g-1 fresh tissue) in patients than in controls. We also found a reduction in glycolytic activity (pyruvate kinase 1009 +/- 79 vs 1625 +/- 26 nmoles. min-1.mg protein-1), despite normal tricarboxylic acid cycle velocity, an increase in alanine amino-transferase (964 +/- 79 vs 425 +/- 34 nmoles. min-1.mg protein-1) and in aspartate aminotransferase (515 +/- 44 vs 291 +/- 56 nmoles.min-1.mg protein-1). An increase was also observed in total NADH cytochrome c reductase (128 +/- 14 vs 68 +/- 5 nmoles.min-1.mg protein-1), while cytochrome oxidase activity was normal. The cortisol/insulin ratio was slightly elevated (77 +/- 4 vs 32 +/- 12). In conclusion, normonutritive patients with severe heart failure show an imbalance in the energy production/utilization ratio. The impairment is probably due both to a decrease in production and an increase in consumption of energy owing to greater cellular workload and/or a hypercatabolic state.
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PMID:Biochemical analysis of muscle biopsy in overnight fasting patients with severe chronic heart failure. 892 17

The relationship between, lipid peroxidation induced by ascorbate and adenosine ADP/Fe3+, and its effect on the respiratory chain activities of beef heart submitochondrial particles has been investigated. Lipid peroxidation, measured as thiobarbituric acid reactive substance formation, resulted in an inhibition of the NADH and succinate oxidase activities. Examination of several partial reactions of the respiratory chain revealed inactivation primarily of those involving endogenous ubiquinone, i.e., NADH- and succinate-ubiquinone1 and cytochrome c reductases. Ubiquinol-cytochrome c reductase, measured with reduced ubiquinone2 as electron donor, was unaffected. The amount of NADH- or succinate-reducible cytochrome b in the presence of cyanide was strongly decreased, but could be recovered by the addition of antimycin. There occurred a substantial decrease of the ubiquinone content in the course of lipid peroxidation, with a linear relationship between this decrease and the NADH and succinate oxidase activities. The results are consistent with the conclusion that the ubiquinone pool undergoes an oxidative modification during lipid peroxidation, to a form that can no longer function as a component of the respiratory chain. Lipid peroxidation also led to a partial inhibition of the succinate dehydrogenase and cytochrome c oxidase activities and a minor decrease of the cytochrome c and cytochrome a contents. Reduction of endogenous ubiquinone prevented lipid peroxidation as well as the concomitant modification of ubiquinone and inactivation of the respiratory chain. These observations suggest that the destruction of ubiquinone through lipid peroxidation is the primary cause of inactivation of the respiratory chain, and emphasize the antioxidant role of ubiquinol in preventing these effects. The possible implications of these findings for regulation of the cellular turnover of ubiquinone by the prevailing oxidative stress are discussed.
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PMID:Lipid peroxidation and changes in the ubiquinone content and the respiratory chain enzymes of submitochondrial particles. 898 Oct 30

Detailed respiration studies on isolated liver mitochondria from streptozotocin-induced diabetic Sprague-Dawley rats revealed a disease-associated decrease in the ADP/O ratio, a marker for mitochondrial ability to couple the consumption of oxygen to the phosphorylation of ADP. This decrease was observed following induction of respiration with glutamate/malate, succinate, or duroquinol, which enter the electron transport chain selectively at complexes I (NADH dehydrogenase), II (succinate dehydrogenase), or III (cytochrome bc1 complex), respectively. These data, coupled with studies using respiratory inhibitors (most importantly antimycin A and myxothiazol), localize at least a portion of this defect to a single site within the electron transport chain (center P in the Q-cycle portion of complex III). These results suggest that liver mitochondria from diabetic animals may generate increased levels of reactive oxygen species at the portion of the electron transport chain already established as the major site of mitochondrial free radical generation. The reduction in the ADP/O ratio occurred in mitochondria that do not have overt defects in the respiratory control ratio or in State 3 and State 4 respiration. The data in this paper suggest that defects in center P of the electron transport chain likely increase mitochondrial exposure to oxidants in the diabetic. This data may partially explain the evidence of altered exposure and/or response to reactive species in mitochondria from diabetics. This work thus provides further clues to the interaction between oxidative stress and diabetes-associated mitochondrial dysfunction.
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PMID:Defects at center P underlie diabetes-associated mitochondrial dysfunction. 911 51

Experiments were performed on eight subjects affected by peripheral arterial occlusive disease (PAOD) of the lower limbs. Each patient was submitted to Ecodoppler, angiography and the "Treadmill test". Two bioptic muscle of these patients. A sample was used for the spectrophotometric and spectrophotofluorimetric determinations of: glycogen, pyruvate, lactate, citrate, alpha-ketoglutarate, malate, aspartate, glutamate, AMP, ADP, ATP and creatine phosphate (CP). The other bioptic sample was used to determine the following enzyme activities: hexokinase, phosphofructokinase, pyruvate kinase, lactate dehydrogenase, citrate synthase, succinate dehydrogenase, malate dehydrogenase, total NADH cytochrome c reductase, cytochrome oxidase, aspartate aminotransferase and alanine aminotransferase. Patients showed an increase in lactate dehydrogenase, total NADH cytochrome c reductase and succinate dehydrogenase activities, a decrease in glycogen, ATP and CP concentrations. Telethermographic data showed patient muscle thermic emission quantitatively different from control group. The telethermographic test can be used as an additional diagnostic tool to determine and monitor the efficiency of a muscle undergoing metabolic failure.
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PMID:Instrumental and metabolic evaluation of patients affected by peripheral arterial occlusive disease (PAOD) following surgical revascularization surgery. 928 78

In this study, the mitochondrial phototoxicity of the cationic rhodacyanine MKT-077 was investigated by comparing its effects on the inhibition of mitochondrial respiration and the structural integrity of mitochondrial DNA (mtDNA) in the presence and absence of added high-intensity visible light (7.5 J/cm2). Results indicate that photoirradiation significantly enhances the mitochondrial toxicity of MKT-077 at both the biochemical and DNA levels. For example, the concentration of MKT-077 required to achieve one-half maximal inhibition of ADP-stimulated respiration was observed to be 6-fold lower in the presence versus absence of high-intensity light (one-half maximal inhibition at 2.5 versus 15 microg MKT-077/ mg, respectively). In addition, photoirradiation produced a 25-fold increase in inhibition of succinate-cytochrome c reductase activity by MKT-077 (one-half maximal inhibition at 2 versus 50 microg MKT-077/ml, +/-light, respectively) and a 6-fold increase in inhibition of cytochrome oxidase activity (one-half maximal inhibition at 5 versus 30 microg MKT-077/ml, +/-light, respectively). Furthermore, the combination of 25 microg/ml MKT-077 and 7.5 J/cm2 visible light caused significant degradation of mtDNA in isolated rat liver mitochondria, whereas the same concentration of dye in the absence of light had only a modest effect on mtDNA. Evaluation of light-induced MKT-077 lipid peroxidation in mitochondrial membrane fragments by the thiobarbituric acid test and by measurement of nonrespiratory-linked oxygen uptake suggests that mitochondrial phototoxicity by MKT-077 may be the result of lipid peroxidation via reactive oxygen species. These results have important implications with regard to the potential use of MKT-077 in photochemotherapy.
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PMID:Photoactivation enhances the mitochondrial toxicity of the cationic rhodacyanine MKT-077. 942 60

In this work, we first compared yeast mitochondrial oxidative metabolism at different levels of organization: whole cells (C), spheroplasts (S), permeabilized spheroplasts (PS) or isolated mitochondria (M). At present, S are more suitable for use than C for biochemical techniques such as fast extraction of metabolites and permeabilization. We show here that respiratory rates of S with various substrates are similar to C, which demonstrate that they are adapted to yeast bioenergetic studies. It appeared from ethanol metabolism +/- NAD+ or NADH respiratory rates on PS that ethanol metabolism was largely cytosolic; moreover, the activity of NADH dehydrogenase was lesser in the case of PS than in S. By comparing PS and M, the biggest difference concerned the respiratory rates of pyruvate and pyruvate-malate, which were much lower for M. Thus mitochondria preparation caused an unidentified loss involved directly in pyruvate metabolism. When the respiratory rate was lowered as a consequence of a high kinetic control of oxidative activity upstream from the respiratory chain, a similar correlation between the increase in ATP/O and decrease in respiratory rate was observed. So, the intrinsic uncoupling of proton pumps is not a particularity of M. Secondly, we demonstrate the existence of a mechanism of retarded diffusion in yeast similar to that already observed in permeabilized mammalian cells for ADP. Such a mechanism also occurs in yeast for several respiratory substrates: the K0.5 for each substrate toward the respiration rate in PS always exceeds that for M. It is proposed that such a discrepancy is due to a restriction of metabolite movement across the outer mitochondrial membrane in permeabilized cells, i.e. regulation of the substrate permeability through porin channels. In the porin-deficient yeast mutant, the K0.5 for NADH is not significantly different in either M or PS and is comparable to that of the parent strain PS. This result confirms that this retarded diffusion is essentially due to the opening-closing of the porin channel.
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PMID:Yeast mitochondrial metabolism: from in vitro to in situ quantitative study. 974 13

Amniocytes represent a population of foetal cells that can be used for prenatal diagnosis in families with suspected mitochondrial oxidative phosphorylation (OXPHOS) defects. In this paper, we present a complex protocol for evaluation of the function of mitochondrial OXPHOS enzymes in cultured amniocytes using three independent and complementary methods: (a) spectrophotometry as a tool for determination of the capacities of mitochondrial respiratory-chain enzymes (NADH ubiquinone oxidoreductase, succinate- and glycerophosphate cytochrome c reductase, cytochrome c oxidase and citrate synthase); (b) polarography as a tool for the evaluation of mitochondrial OXPHOS enzyme functions in situ using digitonin-permeabilised amniocytes (rotenone-sensitive oxidation of pyruvate+malate, antimycin A-sensitive oxidation of succinate, KCN-sensitive oxidation of cytochrome c, ADP-activated substrate oxidation) and (c) cytofluorometric determination of tetramethyl rhodamine methyl ester (TMRM) fluorescence in digitonin-permeabilised amniocytes as a sensitive way to determine the mitochondrial membrane potential under steady-state conditions (state 4 with succinate). These protocols are presented together with reference control values using 9-22 independent cultures of amniocytes.
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PMID:Activities of mitochondrial oxidative phosphorylation enzymes in cultured amniocytes. 1087 12

Treatment of rat liver mitochondria with aluminum in the presence of Ca2+ results in large amplitude swelling accompanied by loss of endogenous Mg2+ and K+ and oxidation of endogenous pyridine nucleotides. The presence of cyclosporin A, ADP, bongkrekic acid, N-ethylmaleimide and dithioerythritol prevent these effects, indicating that binding of aluminum to the inner mitochondrial membrane, most likely at the level of adenine nucleotide translocase, correlates with the induction of the membrane permeability transition (MPT). Indeed, aluminum binding promotes such a perturbation at the level of ubiquinol-cytochrome c reductase, which favors the production of reactive oxygen species. These metabolites generate an oxidative stress involving two previously defined sites in equilibrium with the glutathione and pyridine nucleotides pools, the levels of which correlate with the increase in MPT induction. Although the above-described phenomena are typical of MPT, they are not paralleled by other events normally observed in response to treatment with inducers of MPT (e.g., phosphate), such as the collapse of the electrochemical gradient and the release of accumulated Ca2+ and oxidized pyridine nucleotides. Biochemical and ultrastructural observations demonstrate that aluminum induces a pore opening having a conformation intermediate between fully open and closed in a subpopulation of mitochondria. While inorganic phosphate enhances the MPT induced by ruthenium red plus a deenergizing agent, aluminum instead inhibits this phenomenon. This finding suggests the presence of a distinct binding site for aluminum differing from that involved in MPT induction.
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PMID:Aluminum as an inducer of the mitochondrial permeability transition. 1108 52

In addition to an anti-inflammatory effect, sulindac, one of the non-steroidal anti-inflammatory drugs (NSAIDs), has been shown to have a protective effect against the incidence and mortality of colorectal cancer. However, the molecular basis of its anti-proliferative function remains unclear. To investigate its molecular mechanism, we exposed 11 colon-cancer cell lines to NSAIDs such as aspirin, sulindac and the sulfide and sulfone metabolites of sulindac. Sensitivity to these drugs was dose- and time-dependent but varied from one cell line to another. Among the cell lines examined, sulindac showed a moderate anti-proliferative effect on HT-29 colon cancer cells and caused morphological changes, including an increase of cells with abnormal DNA content. We used the mRNA fluorescence differential display method with these cells to identify molecules that might contribute, through altered expression, to cellular changes in response to NSAIDs. Sixty-eight cDNA fragments were confirmed by RT-PCR to have significantly different expression levels following sulindac treatment. Thirty of these fragments proved to be novel cDNA sequences or identical to expressed sequence tags; the other 38 fragments were identical, or showed significant homology, to genes whose function was already known. Among the known genes differentially expressed in HT-29 cells after sulindac treatment were those encoding acetylglucosaminyltransferase, ferritin heavy chain, zinc finger protein 165, aldose reductase, carcinoembryonic antigen, aldoketoreductase, NF-kappaB-activating kinase, lysosome-associated protein, RhoE = 26 kDa GTPase homologue, NADH oxidoreductase, G/T mismatch bindingprotein, TM7SF3, ADP/ATP carrier-like protein and chromosome segregation protein. This variety among classes of proteins affected by sulindac in our experiments underscores the complexity of anti-proliferative mechanisms that may operate in colon-cancer cells treated with NSAIDs. Furthermore, identification of genes regulated by NSAIDs in colon-cancer cells should provide useful information to identify novel therapeutic targets for treatment and/or prevention of colon cancer.
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PMID:Growth-suppressive effect of non-steroidal anti-inflammatory drugs on 11 colon-cancer cell lines and fluorescence differential display of genes whose expression is influenced by sulindac. 1109 8


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