Tissue-specific oxidative imbalance and mitochondrial dysfunction during Trypanosoma cruzi infection in mice

In this study, we examined the tissue specificity of inflammatory and oxidative responses and mitochondrial dysfunction in mice infected by Trypanosoma cruzi. In acute mice, parasite burden and associated inflammatory infiltrate was detected in all tissues (skeletal muscle>heart>stomach>colon). The extent of oxidative damage and mitochondrial decay was in the order of heart>stomach>skeletal muscle>colon. In chronic mice, a low level of parasite burden and inflammation continued in all tissues; however, oxidant overload and mitochondrial inefficiency mainly persisted in the heart tissue (also detectable in stomach). Further, we noted an unvaryingly high degree of oxidative stress, compromised antioxidant status, and decreased mitochondrial respiratory complex activities in peripheral blood of infected mice. A pair-wise log analysis showed a strong positive correlation in the heart-versus-blood (but not other tissues) levels of oxidative stress markers (malonyldialdehyde, glutathione disulfide), antioxidants (superoxide dismutase, MnSOD, catalase), and mitochondrial inhibition of respiratory complexes (CI/CIII) in infected mice. T. cruzi-induced acute inflammatory and oxidative responses are widespread in different muscle tissues. Antioxidant/oxidant status and mitochondrial function are consistently attenuated in the heart, and reflected in the peripheral-blood of T. cruzi-infected mice. Our results provide an impetus to investigate the peripheral-blood oxidative responses in relation to clinical severity of heart disease in chagasic human patients.     

Enhancement of cytotoxicity of hydrogen peroxide by hyperthermia in chinese hamster ovary cells: role of antioxidant defenses

Regional hyperthermia has potential for human cancer treatment, particularly in combination with systemic chemotherapy or radiotherapy. The mechanisms involved in heat-induced cell killing are currently unknown. Hyperthermia may increase oxidative stress in cells, and thus, oxidative stress could have a role in the mechanism of cell death. We use hydrogen peroxide as a model oxidant to improve understanding of interactions between heat and oxidative stress. Heat increased cytotoxicity of hydrogen peroxide in Chinese hamster ovary cells. Altered levels of cellular antioxidants should create an imbalance between prooxidant and antioxidant systems, thus modifying cytotoxic responses to heat and to oxidants. We determine the involvement of the two cellular antioxidant defenses against peroxides, catalase and the glutathione redox cycle, in cellular sensitivity to heat, to hydrogen peroxide, and to heat combined with the oxidant. Defense systems were either inhibited or increased. For inhibition studies, intracellular glutathione was diminished to less than 15% of its initial level by treatment with L-buthionine sulfoximine (1 mM, 24 h). Inhibition of catalase was achieved with 3-amino-1,2,4-triazole (20 mM, 2 h), which caused a 80% decrease in endogenous enzyme activity. To increase antioxidants, cells were pretreated with the thiol-containing reducing agents, N-acetyl-L-cysteine, 2-oxo-4-thiazolidine carboxylate, and 2-mercaptoethane sulfonate. These compounds increased intracellular glutathione levels by 30%. Catalase activity was increased by addition of exogenous enzyme to cells. We show that levels of glutathione and catalase affect cellular cytotoxic responses to heat and hydrogen peroxide, either used separately or in combination. These findings are relevant to mechanisms of cell killing at elevated temperatures and suggest the involvement of oxidative stress.     

Stress proteins in plants

Summary

Several environmental stresses elicit specific plant genomic responses. These include temperature extremes, oxidative stress, water stress, anaerobiosis as well as pathogen attack. Molecular biological approaches are now yielding insights into the mechanisms whereby plant cells perceive the stress of temperature extremes and activate their defences in response at the gene level. These responses appear to be interconnected with responses to oxidative stress in plants and an outcome is a greater appreciation of the role, and the genetic regulation, of two important groups of ‘stress proteins’, namely the heat shock proteins and the antioxidant enzymes.     

The role of DNA repair in brain related disease pathology

Oxidative DNA damage is implicated in brain aging, neurodegeneration and neurological diseases. Damage can be created by normal cellular metabolism, which accumulates with age, or by acute cellular stress conditions which create bursts of oxidative damage. Brain cells have a particularly high basal level of metabolic activity and use distinct oxidative damage repair mechanisms to remove oxidative damage from DNA and dNTP pools. Accumulation of this damage in the background of a functional DNA repair response is associated with normal aging, but defective repair in brain cells can contribute to neurological dysfunction. Emerging research strongly associates three common neurodegenerative conditions, Alzheimer's, Parkinson's and stroke, with defects in the ability to repair chronic or acute oxidative damage in neurons. This review explores the current knowledge of the role of oxidative damage repair in preserving brain function and highlights the emerging models and methods being used to advance our knowledge of the pathology of neurodegenerative disease.     

Persistent oxidative stress following renal ischemia-reperfusion injury increases ANG II hemodynamic and fibrotic activity

ANG II is a potent renal vasoconstrictor and profibrotic factor and its activity is enhanced by oxidative stress. We sought to determine whether renal oxidative stress was persistent following recovery from acute kidney injury (AKI) induced by ischemia-reperfusion (I/R) injury in rats and whether this resulted in increased ANG II sensitivity. Rats were allowed to recover from bilateral renal I/R injury for 5 wk and renal blood flow responses were measured. Post-AKI rats showed significantly enhanced renal vasoconstrictor responses to ANG II relative to sham-operated controls and treatment of AKI rats with apocynin (15 mM, in the drinking water) normalized these responses. Recovery from AKI for 5 wk resulted in sustained oxidant stress as indicated by increased dihydroethidium incorporation in renal tissue slices and was normalized in apocynin-treated rats. Surprisingly, the renal mRNA expression for common NADPH oxidase subunits was not altered in kidneys following recovery from AKI; however, mRNA screening using PCR arrays suggested that post-AKI rats had decreased renal Gpx3 mRNA and an increased expression other prooxidant genes such as lactoperoxidase, myeloperoxidase, and dual oxidase-1. When rats were infused for 7 days with ANG II (100 ng·kg(-1)·min(-1)), renal fibrosis was not apparent in sham-operated control rats, but it was enhanced in post-AKI rats. The profibrotic response was significantly attenuated in rats treated with apocynin. These data suggest that there is sustained renal oxidant stress following recovery from AKI that alters both renal hemodynamic and fibrotic responses to ANG II, and may contribute to the transition to chronic kidney disease following AKI.     

The influence of season on oxidant-antioxidant status in trained and sedentary subjects

The association between oxidative stress and cardiovascular diseases is a widely accepted fact today. Generally, men have a higher risk of cardiovascular incidents and mortality from acute myocardial infarction and strokes. We have examined sport-associated circannual rhythms of oxidant and antioxidant processes by measuring plasma LPO, erythrocyte SOD, CAT, Gpx activity and plasma hormonal status in both sedentary and long-term trained men and women. We have shown seasonal variations in both oxidant and antioxidant status in all examined groups. The largest difference was observed in the oxidant status between sedentary men and women during autumn and winter, which is considered a period of high coronary risk for men. Sport decreased LPO in trained men in autumn, while the same effect in trained women was shifted towards summer. These data state that regular, long-term physical exercise training induces adaptive responses that confer protection against oxidative stress, as well as the beneficial effect of exercise with regard to season, particularly in men during a period of high coronary risk (autumn and winter, respectively) and in women during summer.     

Oxidative stress in biological systems and its relation with pathophysiological functions: the effect of physical activity on cellular redox homeostasis

The body of evidence from the past three decades demonstrates that oxidative stress can be involved in several diseases. This study aims to summarise the current state of knowledge on the association between oxidative stress and the pathogenesis of some characteristic to the biological systems diseases and aging process. This review also presents the effect of physical activity on redox homeostasis. There is strong evidence from studies for participation of reactive oxygen and nitrogen species in pathogenesis of acute and chronic diseases based on animal models and human studies. Elevated levels of pro-oxidants and various markers of the oxidative stress and cells and tissues damage linked with pathogenesis of cancer, atherosclerosis, neurodegenerative diseases hypertension, diabetes mellitus, cardiovascular disease, atherosclerosis, reproductive system diseases, and aging were reported. Evidence confirmed that inflammation contributes widely to multiple chronic diseases and is closely linked with oxidative stress. Regular moderate physical activity regulates oxidative stress enhancing cellular antioxidant defence mechanisms, whereas acute exercise not preceded by training can alter cellular redox homeostasis towards higher level of oxidative stress. Future studies are needed to clarify the multifaceted effects of reactive oxygen/nitrogen species on cells and tissues and to continue study on the biochemical roles of antioxidants and physical activity in prevention of oxidative stress-related tissue injury.     

Modulation of antioxidant defense by <Emphasis Type="Italic">Alpinia galanga</Emphasis> and <Emphasis Type="Italic">Curcuma aromatica</Emphasis> extracts correlates with their inhibition of UVA-induced melanogenesis

Ultraviolet A (UVA) irradiation is suggested to contribute to melanogenesis through promoting cellular oxidative stress and impairing antioxidant defenses. An overproduction of melanin can be associated with melanoma skin cancer and hyperpigmentation. Therefore, developing effective antimelanogenic agents is of importance. Alpinia galanga (AG) and Curcuma aromatica (CA) are traditional medicinal plants widely used for skin problems. Hence, this study investigated the antimelanogenic effects of AG and CA extracts (3.8–30 μg/ml) by assessing tyrosinase activity, tyrosinase mRNA levels, and melanin content in human melanoma cells (G361) exposed to UVA. The roles in protecting against melanogenesis were examined by evaluating their inhibitory effects on UVA-induced cellular oxidative stress and modulation of antioxidant defenses including antioxidant enzymes, catalase (CAT) and glutathione peroxidase (GPx), and intracellular glutathione (GSH). In addition, possible active compounds accountable for biological activities of the extracts were identified by thin layer chromatography (TLC)-densitometric analysis. Our study demonstrated that UVA (8 J/cm²) induced both tyrosinase activity and mRNA levels and UVA (16 J/cm²)-mediated melanin production were suppressed by the AG or CA extracts at noncytotoxic concentrations. Both extracts were able to protect against UVA-induced cellular oxidant formation and depletion of CAT and GPx activities and GSH content in a dose-dependent manner. Moreover, TLC-densitometric analysis detected the presence of eugenol and curcuminoids in AG and CA, respectively. This is the first report representing promising findings on AG and CA extract-derived antityrosinase properties correlated with their antioxidant potential. Inhibiting cellular oxidative stress and improving antioxidant defenses might be the mechanisms by which the extracts yield the protective effects on UVA-dependent melanogenesis.     

The role of oxidative stress in ambient particulate matter-induced lung diseases and its implications in the toxicity of engineered nanoparticles

Ambient particulate matter (PM) is an environmental factor that has been associated with increased respiratory morbidity and mortality. The major effect of ambient PM on the pulmonary system is the exacerbation of inflammation, especially in susceptible people. One of the mechanisms by which ambient PM exerts its proinflammatory effects is the generation of oxidative stress by its chemical compounds and metals. Cellular responses to PM-induced oxidative stress include activation of antioxidant defense, inflammation, and toxicity. The proinflammatory effect of PM in the lung is characterized by increased cytokine/chemokine production and adhesion molecule expression. Moreover, there is evidence that ambient PM can act as an adjuvant for allergic sensitization, which raises the possibility that long-term PM exposure may lead to increased prevalence of asthma. In addition to ambient PM, rapid expansion of nanotechnology has introduced the potential that engineered nanoparticles (NP) may also become airborne and may contribute to pulmonary diseases by novel mechanisms that could include oxidant injury. Currently, little is known about the potential adverse health effects of these particles. In this communication, the mechanisms by which particulate pollutants, including ambient PM and engineered NP, exert their adverse effects through the generation of oxidative stress and the impacts of oxidant injury in the respiratory tract will be reviewed. The importance of cellular antioxidant and detoxification pathways in protecting against particle-induced lung damage will also be discussed.     

Local and systemic oxidant/antioxidant status before and during lung cancer radiotherapy

To examine local and systemic oxidative status of lung cancer (LC) and oxidant effects of radiotherapy (RT), this study evaluated antioxidants and markers of oxidative and nitrosative stress in bronchoalveolar lavage (BAL) fluid and in the blood of 36 LC patients and 36 non-cancer controls at baseline and during and after RT for LC. LC patients had higher baseline serum urate, plasma nitrite and lower serum oxidized proteins than controls (p=0.016, p<0.001 and p=0.027, respectively), but BAL fluid oxidative stress markers were similar. RT tended to raise some antioxidants, however, significant increases were seen in serum urate, conjugated dienes and TBARS (p=0.044, p=0.034 and p=0.004, respectively) 3 months after RT. High urate at baseline may compensate against the oxidative stress caused by LC. RT shifts the oxidant/antioxidant balance towards lipid peroxidation, although the antioxidant defense mechanisms of the body appear to counteract the increased oxidative stress rather effectively.     

Stress,Aging, and Brain Oxidative Damage

Stress may contribute to aging acceleration and age-related degenerative diseases. Stress and adaptation to stress require numerous homeostatic adjustments including hormones, neurotransmitters, oxidants, and other mediators. The stress-induced hormones, neurotransmitters, and oxidants all have beneficial, but also harmful effects if out of balance. Therefore, the homeostasis of stress and adaptation should be governed by the hormone balance, neurotransmitter balance, and oxidant balance, as well as the interactions among these substances. The imbalance and the over-interaction of these balances may ultimately cause increased oxidant generation and oxidative damage to biomolecules. This increased oxidative damage may add to the oxidant burden associated with normal aerobic metabolism, which in itself, generates oxidants, causes accumulation of oxidative damage in mitochondria, and contributes to normal aging. Therefore, the stress-associated increase of oxidative damage may, in part, contribute to stress-associated aging acceleration and age-related neurodegenerative diseases.     

Developmental differences in hyperoxia-induced oxidative stress and cellular responses in the murine lung

Exposure of newborn mice to high inspired oxygen elicits a distinct phenotype of compromised alveolar and vascular development, although lethality during long-term exposure is lower in newborns compared to adults. As the effects of hyperoxia are mediated by excessive reactive oxygen species (ROS) generation, we hypothesized that newborn mice may exhibit enhanced expression of antioxidant defenses or attenuated ROS generation compared with adults. We measured subcellular oxidant responses to acute hyperoxia in lung slices and alveolar epithelial cells at varying time points during postnatal murine lung development. Oxidant stress was assessed using RoGFP, a ratiometric protein thiol redox sensor, targeted to the cytosol or the mitochondrial matrix. In contrast to newborn resistance to oxygen-induced mortality, cells of lung slices from younger mice demonstrated exaggerated mitochondrial matrix oxidant stress compared to adults, whereas oxidant stress responses in the cytosol were absent. Cell death in lung slices from newborn mice exposed to 48 h of hyperoxia was also greater than for adults. Consistent with these findings, expression of antioxidant enzymes in newborn lungs was lower than in adults, and induction of antioxidant levels and activity during 24 h of in vivo exposure was absent. However, expression of the reactive oxygen species-generating enzyme NADPH oxidase 1 was increased with hyperoxic exposure in the young but not the adult lung. Collectively, these results suggest that the greater lethality in adult animals may be more likely attributed to processes such as inflammation than to differences in antioxidant defenses. Therapies for neonatal and adult oxidative lung injury should therefore consider and address developmental differences in oxidative stress responses.     

Mitochondrial Enzymes and Endoplasmic Reticulum Calcium Stores as Targets of Oxidative Stress in Neurodegenerative Diseases

Considerable evidence indicates that oxidative stress accompanies age-related neurodegenerative diseases. Specific mechanisms by which oxidative stress leads to neurodegeneration are unknown. Two targets of oxidative stress that are known to change in neurodegenerative diseases are the mitochondrial enzyme alpha-ketoglutarate dehydrogenase complex (KGDHC) and endoplasmic reticulum calcium stores. KGDHC activities are diminished in all common neurodegenerative diseases and the changes are particularly well documented in Alzheimer's disease (AD). A second change that occurs in cells from AD patients is an exaggerated endoplasmic reticulum calcium store [i.e., bombesin-releasable calcium stores (BRCS)]. H(2)O(2), a general oxidant, changes both variables in the same direction as occurs in disease. Other oxidants selectively alter these variables. Various antioxidants were used to help define the critical oxidant species that modifies these responses. All of the antioxidants diminish the oxidant-induced carboxy-dichlorofluorescein (cDCF) detectable reactive oxygen species (ROS), but have diverse actions on these cellular processes. For example, alpha-keto-beta-methyl-n-valeric acid (KMV) diminishes the H(2)O(2) effects on BRCS, while trolox and DMSO exaggerate the response. Acute trolox treatment does not alter H(2)O(2)-induced changes in KGDHC, whereas chronic treatment with trolox increases KGDHC almost threefold. The results suggest that KGDHC and BRCS provide targets by which oxidative stress may induce neurodegeneration and a useful tool for selecting antioxidants for reversing age-related neurodegeneration.     

草酸对氧化胁迫-水稻叶片中核酮糖-1，5-二磷酸羧化酶/加氧酶降解的保护作用

以杂交稻(汕优63)为试验材料,在木村B营养液中培养至三叶期,用草酸5mmol/L预处理水稻2d,再处以氧化胁迫(用0．1mmol／L浓度的活性氧诱发剂甲基紫精处理)。结果表明MV诱发的氧化胁迫下,Rubisco及其它可溶性蛋白快速降解。草酸预处理可明显缓解Rubisco及其它可溶性蛋白的降解,降解速率分别降低1／3和1／2左右。植株经草酸处理后其叶片中几种抗氧化酶如AsA-POD、SOD、CAT活性大大提高,这可能是草酸预处理可缓解氧化胁迫下Rubisco和其它可溶性蛋白降解的重要原因。既然草酸能有效地诱导植物的抗氧化防卫反应,它可能作为一种诱抗剂来提高植物的抗逆性。     

Oxidative stress induces senescence in human mesenchymal stem cells

Mesenchymal stem cells (MSCs) contribute to tissue repair in vivo and form an attractive cell source for tissue engineering. Their regenerative potential is impaired by cellular senescence. The effects of oxidative stress on MSCs are still unknown. Our studies were to investigate into the proliferation potential, cytological features and the telomere linked stress response system of MSCs, subject to acute or prolonged oxidant challenge with hydrogen peroxide. Telomere length was measured using the telomere restriction fragment assay, gene expression was determined by rtPCR. Sub-lethal doses of oxidative stress reduced proliferation rates and induced senescent-morphological features and senescence-associated β-galactosidase positivity. Prolonged low dose treatment with hydrogen peroxide had no effects on cell proliferation or morphology. Sub-lethal and prolonged low doses of oxidative stress considerably accelerated telomere attrition. Following acute oxidant insult p21 was up-regulated prior to returning to initial levels. TRF1 was significantly reduced, TRF2 showed a slight up-regulation. SIRT1 and XRCC5 were up-regulated after oxidant insult and expression levels increased in aging cells. Compared to fibroblasts and chondrocytes, MSCs showed an increased tolerance to oxidative stress regarding proliferation, telomere biology and gene expression with an impaired stress tolerance in aged cells.     

Cholesteryl ester oxidation products in atherosclerosis

Lipid oxidation products are formed at sites of increased oxidant stress and have been shown to accumulate in atherosclerotic lesions. Although recent studies have focused on the formation and metabolism of oxidized lipids, very little is known about their biological activities and possible (patho)physiological functions. Oxidation of cholesteryl esters containing unsaturated fatty acids leads to the formation of hydroperoxides that are either reduced to alcohols or degrade into biologically active "core-aldehydes". In this review, the mechanisms of formation and metabolic fate of oxidized cholesteryl esters, their occurrence, as well as possible biological activities are discussed. Based on the current knowledge, cholesteryl ester oxidation leads to the formation of biologically active substances, which could actively contribute to the progression of atherosclerotic lesions and their resulting complications.     

Zinc deficiency induces oxidative stress and AP-1 activation in 3T3 cells

It has been postulated that one mechanism underlying zinc deficiency-induced tissue alterations is excessive cellular oxidative damage. In the present study we investigated if zinc deficiency can induce oxidative stress in 3T3 cells and trigger select intracellular responses that have been associated to oxidative stress. Cells were exposed to control media or to chelated media containing 0.5, 5, or 50 microM zinc for 24 or 48 h. The oxidative status of the cells was evaluated as an increase in the fluorescence of the probe 5(or 6)-carboxy-2'7'-dichlorodihydrofluorescein diacetate (DCDCDHF). After 24 and 48 h of exposure, the fluorescence intensity was significantly higher (4- to 15-fold) in the 0.5 and 5 microM Zn groups compared to the 50 microM Zn and control groups. The activity of the antioxidant enzymes CuZn (CuZnSOD) and Mn (MnSOD) superoxide dismutases was significantly higher in the 0.5 and 5 microM Zn cells compared to the 50 microM Zn and control groups at both the 24 and 48 h time points. These higher activities were associated with higher levels of MnSOD mRNA. After 24 h in culture, the level of activated AP-1 was markedly higher in the 0.5 and 5 microM Zn cells than in the control (72 and 58%, respectively) and 50 microM Zn cells (73 and 60%, respectively). NF-kappaB binding activity was lower in the 0.5 and 5 microM Zn cells than in controls. Thus, oxidative stress is induced by zinc deficiency in 3T3 cells. This oxidative stress results in an upregulation of oxidant defense mechanisms.     

Rapid in vivo screening system for anti‐oxidant activity using bacterial redox sensor strains

Aim: To develop a faster and easier in vivo method to screen compounds for anti‐oxidant activity using a microbial system. Methods and Results: Bacterial redox sensor‐based assay systems were applied. The activities of SoxR and OxyR, the bacterial redox sensors, were monitored to probe the intracellular redox status through two reporter strains, Escherichia coli soxS_p‐lacZ and oxyS_p‐lacZ fusions, which specifically respond to paraquat, a superoxide generator, and H₂O₂, respectively, with practically no cross reactivity. For the test screening, 27 natural compounds including phenolics and flavonoids that are putatively considered anti‐oxidant nutritional supplements were collected and assayed for their capability to alleviate oxidative stress in these bacterial systems. Among them, rutin, kaempferol and quercetin had significant anti‐H₂O₂ activity, and betaine, glycyrrhizic acid and baicalin had weak anti‐superoxide activity. While rutin, kaempferol and quercetin significantly reduced the H₂O₂ stress at low concentrations, betaine, glycyrrhizic acid and baicalin required higher concentration for their anti‐superoxide effects. In vitro, only quercetin protected DNA in a metal‐catalysed oxidation system, suggesting that the other compounds might indirectly exert their anti‐oxidant activities through other biological functions. Finally, quercetin, rutin and kaempferol significantly restored the viability of a superoxide dismutase mutant that has limited viability because of defective defence against oxidative stress. Conclusion: These bacterial systems could provide a more efficient method for measuring the activity of compounds affecting cellular oxidative stress and viability. Significance and Impact of the Study: The demand for anti‐oxidant and anti‐ageing activities is increasing in one of the fastest growing segments of the functional food market, but the screening for these activities is currently very laborious, expensive and time consuming. This study suggests a basis for a high throughput screening method for these activities.