肾病综合征患儿血红细胞磷脂过氧化氢谷胱甘肽过氧化物酶活力的研究

本文对１７例肾病综合征（ＮＳ）患儿和１５例健康对照组儿童血红细胞磷脂过氧化氢谷胱甘肽过氧化物酶（ＰＨＧＰｘ）活力，脂溶性荧光色素（ＬＳＦＰ）含量进行了研究。结果表明，ＮＳ急性期ＰＨＧＰｘ活力明显降低．ＬＳＦＰ含量增加；恢复期ＰＨＧＰｘ活力较急性期明显提高，但仍低于正常对照组，ＬＳＦＰ虽较急性期下降，但仍高于正常对照组。说明ＮＳ存在ＰＨＧＰｘ和ＬＳＦＰ的改变，但可逐渐恢复。     

Attenuation of cytotoxicity induced by tBHP in H9C2 cells by Bacopa monniera and Bacoside A

Cardiovascular diseases are one of the major global health issues leading to morbidity and mortality across the world. In the present study Bacopa monniera and its major bioactive component, Bacoside A (Bac-A) was used to evaluate its cytoprotective property in H9C2 cardiomyocytes against tBHP (150?μM) induced ROS-mediated oxidative stress and apoptosis. Our results implicate that pre-treatment with hydroalcoholic extract of Bacopa monniera (BME) and Bac-A (125?μg/ml and 6?μg/ml respectively) significantly restored oxidative stress by scavenging the free radicals and also elevated phase II antioxidant defensive enzymes such as (SOD, CAT, GR, GPx and GSH). Membrane integrity was estimated by MMP and LDH assays and found 89 and 72% of the protective effect. Further immunoblotting studies confirmed anti-apoptotic effects by regulating protein expression like Bcl2 was up-regulated to 99 and 85% and Bax was down-regulated to 122 and 181%, iNOS by 154.38 and 183.45% compared to tBHP (277.48%) by BME and Bac-A. BME and Bac-A exerts cytoprotective efficacy by attenuation of ROS generated through oxidative stress by an increase in the concentration of antioxidant enzymes and sustain membrane integrity which leads to restoring the damage caused by tBHP.     

Mutation of alkyl hydroperoxide reductase gene ahpC of Xanthomonas oryzae pv. oryzae affects hydrogen peroxide accumulation during the rice–pathogen interaction

Hydrogen peroxide (H₂O₂) is usually generated by normal aerobic respiration of pathogens and by the host defense response during plant–pathogen interactions. In this study, histochemical localization of H₂O₂ accumulation in rice inoculated with the wild-type strain (PXO99^A) and the gene deletion mutant (ΔahpC) of alkyl hydroperoxide reductase subunit C (AhpC) of Xanthomonas oryzae pv. oryzae (Xoo), the bacterial blight pathogen of rice, was analyzed. The ΔahpC mutant displayed a significant decrease in endogenous H₂O₂ accumulation which was induced by the compensatory increase in H₂O₂ scavenging activity. The change in the bacterial endogenous H₂O₂ level affected the total amount of H₂O₂ accumulation during the interaction with rice plants. These results suggested that Xoo contributes to H₂O₂ accumulation in rice in a compatible interaction, and pathogen-driving H₂O₂ is in association with cell collapse of rice.     

The dietary antioxidants resveratrol and quercetin protect cells from exogenous pro-oxidative damage.

In the colorectal epithelium oxidative stress is observed endogenously in premalignant adenoma cells or induced by nutritional factors like fatty acid hydroperoxides (LOOH). Bioactive phenols like resveratrol and quercetin can quench reactive oxygen species and protect from pro-oxidative damage. Our study used colorectal adenoma and carcinoma cell lines to assess antioxidant protective effects of resveratrol and quercetin. It demonstrated that both compounds efficiently protect from oxidative stress induced by LOOH. Effective concentrations (10 microM resveratrol and 1 microM quercetin) can easily be reached in the intestinal lumen after consumption of plant foods or food supplements. Both compounds prevent LOOH-induced formation of intracellular H2O2, stimulation of cyclooxygenase-2 and vascular endothelial growth factor. For reduction of endogenous H2O2 levels in colorectal tumor cells higher antioxidant-concentrations are needed in all cell lines. Quercetin (10 microM) alone even increased H2O2 in LT97 adenoma cells and stimulated VEGF production. Resveratrol and quercetin also induced 10-30% and 40-60% cell loss respectively by apoptosis. In summary, this indicates that resveratrol and quercetin have little protective capacity in absence of exogenous stress. They are however highly efficient in protecting against nutrition induced oxidative stress damage suggesting that this constitutes the major part of their tumor protective activity.     

Potent suppressive activity of fresh and dried peels from Satsuma mandarin Citrus unshiu (Marcorv.) on hydroperoxide generation from oxidized linoleic acid

The effects of various extracts prepared from fresh and dried peels of Satsuma mandarin (Citrus unshiu Marcov.) on hydroperoxide generation from oxidized linoleic acid were compared under different extraction conditions. The cold-and hot-water extracts of fresh peels showed significant suppressive activity against hydroperoxide generation in a dose-dependent manner. However, the methanol or acetone extract of fresh peels did not exhibit significant suppressive effects. The commercially available ascorbic acids equivalent to their concentrations in the water extracts of fresh peels showed roughly equal antioxidative activities compared with those of the water extracts of fresh peels. Although the cold- and hot- water extracts of dried peels indicated a considerable reduction of ascorbic acid concentration, they exhibited much higher antioxidative activities than those of the fresh peels. The methanol extract of dried peels also showed significant antioxidative activities, but did not contain significant ascorbic acid. These results suggest that the fresh peels of Satsuma mandarin have potential antioxidant activities, and the drying treatment of fresh peels caused an enhancement of the antioxidant activity. The pharmacological significance of this finding is discussed.     

The importance of weak absorption features in promoting tropospheric radical production

Atmospheric field measurement and modeling studies have long noted discrepancies between observation and predictions of OH and HO(2) concentrations in the atmosphere. Novel photochemical mechanisms have been proposed to explain these differences. Although inclusion of these additional sources improves agreement, they are unable to fully account for the observations. We report and demonstrate the importance of weak electronic absorption features, normally ignored or not measured, in contributing to significant OH radical production. Experiments on methyl hydroperoxide, a prototypical organic peroxide in large abundance in the troposphere, highlights how photochemistry in the neglected electronic absorption tail makes an important addition to the tropospheric OH budget. The present results underscore the need to measure absorption cross sections for atmospheric molecules over a wider dynamic range, especially over the wavelength regions where the solar flux is high, to fully quantitate their contributions to atmospheric photochemistry.     

Curcumin protects mitochondria from oxidative damage and attenuates apoptosis in cortical neurons

AIM: To investigate the effect of curcumin on tert-butyl hydroperoxide (t-BHP)-induced oxidative damage in rat cortical neurons and to explore the possible mechanism. METHODS: Primary cultured rat cortical neurons wereperformed in vitro and cell viability was measured by MTT assay. DNA fragmentation was used to evaluate cellapoptosis. Intracellular reactive oxygen species (ROS) and mitochondrial membrane potential (Aψm) was determined by flow cytometric assay. Cellular glutathione (GSH) content was measured by spectrophotometer.‘ Bcl-2family proteins, cytochrome c, cleaved caspase-3, and poly (ADP-ribose) polymerase (PARP) were detected byWestern blot. RESULTS: Exposure of tBHP 100 μmol/L to neurons for 60 rain resulted in △ψm loss and cyto-chrome c release from mitochondria and subsequent activation of caspase-3 and PARP cleavation, and cell apoptosis.After removal of tBHP and then further treatment with curcumin (2.5-20 μmol/L) for 18 h, curcumin abrogated △ψm loss and cytochrome c release, blocked activation of caspase 3, and altered the expression of Bcl-2 family.Further curcumin treatment also prevented cellular GSH and decreased intracellular ROS generation markedly.Curcumin eventually attenuated tBHP-induced apoptosis in cortical neurons. CONCLUSION: Curcumin mayattenuate oxidative damages in cortical neurons by reducing intracellular production of ROS and protecting mito-chondria from oxidative damage.     

Characteristics of tertiary butyl hydroperoxide and hydrogen peroxide conditioned cells withdrawn from peroxide stress

This laboratory has recently reported the preparation of immortal lens epithelial cell lines conditioned to survive in concentrations of peroxide sufficient to cause cataract with in vitro lens culture conditions. The cell conditioning process takes many months during which time the peroxide concentration is gradually increased. It was found that while the acquired resistance to H2O2 was permanent, if tertiary butyl hydroperoxide (TBOOH) was used the resistance was lost within 6-8 weeks of the withdrawal of the peroxide. We now report that resistance is lost within a few days but can be regained within 48 hr. Furthermore, cells resistant to H2O2 while vulnerable to TBOOH could also be rapidly conditioned to tolerate TBOOH in a manner similar to the reconditioning of cells that had lost their TBOOH resistance. The results suggest that a history of exposure to certain oxidative stresses produces a change in cell biology which allows the cell to rapidly respond to the same or other stresses and survive.     

Cumene hydroperoxide induced changes in oxidation–reduction potential in fresh and frozen seminal ejaculates

Oxidation–reduction potential (ORP) is a newer integrated measure of the balance between total oxidants (reactive oxygen species—ROS) and reductants (antioxidants) that reflects oxidative stress in a biological system. This study measures ORP and evaluates the effect of exogenous induction of oxidative stress by cumene hydroperoxide (CH) on ORP in fresh and frozen semen using the MiOXSYS Analyzer. Semen samples from healthy donors (n = 20) were collected and evaluated for sperm parameters. All samples were then flash‐frozen at ?80°C. Oxidative stress was induced by CH (5 and 50 μmoles/ml). Static ORP (sORP—(mV/10⁶ sperm/ml) and capacity ORP (cORP—μC/10⁶ sperm/ml) were measured in all samples before and after freezing. All values are reported as mean ± SEM. Both 5 and 50 μmoles/ml of CH resulted in a significant decline in per cent motility compared to control in pre‐freeze semen samples. The increase in both pre‐freeze and post‐thaw semen samples for sORP was higher in the controls than with 50 μmoles/ml of CH. The change from pre‐freeze to post‐thaw cORP was comparable. The system is a simple, sensitive and portable tool to measure the seminal ORP and its dynamic impact on sperm parameters in both fresh and frozen semen specimens.