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  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The effects of 1-methyl-4-phenylpyridinium (MPP+) on the oxygen consumption, ATP production, H2O2 production, and mitochondrial NADH-CoQ1 reductase (complex I) activity of isolated rat brain mitochondria were investigated. Using glutamate and malate as substrates, concentrations of 10–100 µM MPP+ had no effect on state 4 (−ADP) respiration but decreased state 3 (+ADP) respiration and ATP production. Incubating mitochondria with ADP for 30 min after loading with varying concentrations of MPP+ produced a concentration-dependent decrease in H2O2 production. Incubation of mitochondria with ADP for 60 min after loading with 100 µM MPP+ caused no loss of complex I activity after washing of MPP+ from the mitochondrial membranes. These data are consistent with MPP+ initially binding specifically to complex I and inhibiting both the flow of reducing equivalents and the production of H2O2 by the mitochondrial respiratory chain, without irreversibly damaging complex I. However, mitochondria incubated with H2O2 in the presence of Cu2+ ions showed decreased complex I activity. This study provides additional evidence that cellular damage initiated by MPP+ is due primarily to energy depletion caused by specific binding to complex I, any increased damage due to free radical production by mitochondria being a secondary effect.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-6903
    Keywords: Glutathione ; mitochondria ; N-acetyl aspartate ; oxidative stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of depletion of reduced glutathione (GSH) on brain mitochondrial function and N-acetyl aspartate concentration has been investigated. Using pre-weanling rats, GSH was depleted by L-buthionine sulfoximine administration for up to 10 days. In both whole brain homogenates and purified mitochondrial preparations complex IV (cytochrome c oxidase) activity was decreased, by up to 27%, as a result of this treatment. In addition, after 10 days of GSH depletion, citrate synthase activity was significantly reduced, by 18%, in the purified mitochondrial preparations, but not in whole brain homogenates, suggesting increased leakiness of the mitochondrial membrane. The whole brain N-acetyl aspartate concentration was also significantly depleted at this time point, by 11%. It is concluded that brain GSH is important for the maintenance of optimum mitochondrial function and that prolonged depletion leads also to loss of neuronal integrity. The relevance of these findings to Parkinson's disease and the inborn errors of glutathione mtabolism are also discussed.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-0867
    Keywords: calcium ; compost ; irradiation ; magnesium ; manure ; sewage sludge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Application of organic waste influences crop uptake of Ca and Mg and soil extractability, depending on the nature of the crop and the waste. Four organic wastes: (i) digested sewage sludge (DSS), (ii) irradiated sludge (DISS), (iii) composted sludge (DICSS), and (iv) composted livestock manure (CLM) were applied for two years at rates of 10, 20, 30, and 40 Mg solid ha-1 year-1. Fertilizers N and K were applied to the control treatment (CT), as well as to the waste treatments to supplement crop growth across all treatments, so that these nutrients were not treatment variables. Calcium and Mg concentrations in the tissue of lettuce, bean pods and petunias in 1990 and two cuts of lettuce in 1991, and the CH3COONH4-extractable soil Ca and Mg were determined. Concentration of Ca and Mg in bean pods did not change to the waste application. Calcium concentration in bean pods was less than half of that in other crops. Magnesium concentration in bean pods and petunias was same, but was much lower than in lettuce. Application of DSS, in general, increased Ca concentration in the crops more than did other wastes. The extractable soil Ca was positively correlated with Ca applied with DISS (r=0.453, P〈0.05). Although only a limited amount of Ca was supplied with CLM at the rate of 10 Mg solid ha-1(40 kg Ca ha-1), Ca concentration in petunias increased significantly, then, decreased with increased Ca application (r=0.453, P〈0.05). A similar pattern with CLM was found in the extractable soil Ca. The waste application from all the sources had no influence on crop Mg concentration in 1990, possibly due to low Mg concentration in the wastes. While continuously applied DSS and DISS in 1991 linearly increased Mg concentration in both cuts of lettuce (r=0.867, P〈0.01; r=0.670, P〈0.01 and r=0.671, P〈0.01; r=0.665, P〈0.01 for first cut and second cut of lettuce with DSS and DISS application respectively), application of CLM decreased Mg concentration in first cut lettuce. The patterns of extractable soil Mg were opposite to crop Mg concentration, as the extractable soil Mg linearly increased with CLM, and decreased with the high rate of DSS application. The ability of wastes to supply N was an important factor influencing crop Σ cations (K, Ca and Mg) uptake.
    Type of Medium: Electronic Resource
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