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Antioxidant Response (antioxidant + response)
Terms modified by Antioxidant Response Selected AbstractsBehaviours of Medicago truncatula,Sinorhizobium meliloti Symbioses Under Osmotic Stress in Relation with the Symbiotic Partner Input: Effects on Nodule Functioning and ProtectionJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 3 2009H. Mhadhbi Abstract Three genotypes of the model legume Medicago truncatula were assessed for symbiotic effectiveness in cross inoculation with two strains of Sinorhizobium meliloti under mannitol-mediated osmotic stress. Symbioses showed different tolerance levels revealed on plant growth, nitrogen-fixing capacity and indices of nodule functioning and protection. The variability of stress response was essentially correlated with performance at non-stressful conditions. Symbiosis attitude depended on bacterial partner, host-plant genotype and their interaction. Plant genotype manifested the highest contribution to symbiotic efficiency indices under osmotic stress, even for nodulation and nitrogen fixation where the bacterial strain effect is highly pronounced. Contrasting (tolerant/sensitive) associations were identified for tolerance behaviours, involving the same plant genotype with different rhizobial strains and vice versa. In nodules, osmotic stress leads to accumulation of oxidized lipids and decrease in total protein and leghaemoglobin contents. Antioxidant responses were manifested as induction of guaiacol peroxidase (POX, E.C. 1.11.1.7) and superoxide dismutase (E.C. 1.15.1.1). POX induction was higher in tolerant symbioses and both enzymes were suggested as contributors to the protection of nodule integrity and functioning under osmotic stress. In conclusion, symbiotic efficiency in M. truncatula,S. meliloti combinations under osmotic stress is determined by each symbiont's input as well as the plant,microbe genotype interaction, and POX induction could prove a sensitive marker of tolerant symbioses. [source] High total antioxidant activity and uric acid in tracheobronchial aspirate fluid of preterm infants during oxidative stress: an adaptive response to hyperoxia?ACTA PAEDIATRICA, Issue 3 2000G Vento The effect of O2 exposure, expressed by mean daily fractional inspired oxygen concentration (FiO2), was evaluated during the first 6 d of life in the tracheobronchial aspirate fluid of 16 mechanically ventilated preterm infants in terms of both antioxidant response and oxidative damage, by measuring total antioxidant activity, uric acid concentrations and protein carbonyl content. Each day linear regression analysis was performed and a positive correlation was found between total antioxidant activity and FiO2 during the study period, especially on day 2 of life (r= 0.91, p < 0.0001), but uric acid correlated only in the first 3 d, especially on the 2nd day (r= 0.83, p < 0.0001). No correlation was found between carbonyl content and FiO2. The highest values of total antioxidant activity (416 and 790 ,mol l,1) were found in 2 babies ventilated with highest FiO2: 1 and 0.80, respectively. Total antioxidant activity was not detectable or was very low in the babies not requiring O2 therapy. The highest value of uric acid (270 ,mol l,1) was found in the baby ventilated with 100% oxygen. Uric acid concentrations obtained in these babies were much higher then those reported in the bronchoalveolar lavage fluid of adults. Preterm babies seem to have an antioxidant response in the tracheobronchial aspirate fluid following an oxidative stress and uric acid may be physiologically important as an antioxidant of the respiratory tract, especially during the first days of life. [source] Evaluation of systemic oxidative status and mononuclear leukocytes DNA damage in children with caustic esophageal strictureDISEASES OF THE ESOPHAGUS, Issue 4 2006M. Kaya SUMMARY., Esophageal stricture (ES) due to accidentally caustic digestions is a common problem in children. Mucosal damage and repeated dilatations lead to chronic inflammation and finally ES. We investigated the oxidative status and DNA damage of children with ES. Five children with ES were compared with the same age- and sex-matched healthy subjects. Oxidative status of plasma was evaluated by measuring myeloperoxidase (MPO) activity, and total peroxide (TP) level. Anti-oxidative status of the plasma was evaluated by measuring catalase (CAT) activity, and total antioxidant response (TAR). We used the Single Cell Gel Electrophoresis (also called Comet Assay) to measure DNA strand break in peripheral blood mononuclear leukocytes. Mean MPO activity and TP levels in the ES group were significantly higher than the control group (0.83 ± 0.35, 0.09 ± 0.03 and 0.98 ± 0.38, 0.34 ± 0.20, P = 0.009 and P = 0.047 respectively). There was no significant difference in CAT activity and TAR levels between the two groups (P = 0.347). DNA damage in patients with ES was increased compared to control subjects (108.8 ± 51.2 and 57.6 ± 31.2 arbitrary units, respectively), but this difference was not significant statistically (P= 0.09). This study shows that systemic oxidative stress and alteration at the nuclear level occur in patients with ES, as a result of multiple dilatations and tissue injury. On the other hand, these results support that patients with ES may benefit from antioxidant treatment. [source] The changes in neuromuscular excitability with normobaric hyperoxia in humansEXPERIMENTAL PHYSIOLOGY, Issue 1 2010Christelle Brerro-Saby Based on previous observations in hyperbaric hyperoxia, we hypothesized that normobaric hyperoxia, often used during general anaesthesia and resuscitation, might also induce a neuromuscular excitability. In heathy volunteers, we studied the consequences of a 50 min period of pure oxygen breathing on the neuromuscular conduction time (CT), the amplitude of the compound evoked muscle potential (M-wave), the latency and amplitude of the Hoffman reflex (H reflex) and the electromyographic tonic vibratory response (TVR) of the flexor digitorum superficialis muscle to explore the proprioceptive reflex loop. Hyperoxia-induced oxidative stress was measured by the changes in blood markers of lipid peroxidation (thiobarbituric acid reactive substances, TBARS) and antioxidant response (reduced ascorbic acid, RAA). During hyperoxia, the M-wave amplitude increased, both CT and H reflex latency were shortened, and the H reflex amplitude increased. By contrast, TVR significantly decreased. Concomitantly, an oxidative stress was assessed by increased TBARS and decreased RAA levels. This study shows the existence of dual effects of hyperoxia, which facilitates the muscle membrane excitability, nerve conduction and spinal reflexes, but reduces the gain of the proprioceptive reflex loop. The activation of the group IV muscle afferents by hyperoxia and the resulting oxidative stress might explain the TVR depression. [source] Enhanced formation of advanced oxidation protein products in IBDINFLAMMATORY BOWEL DISEASES, Issue 6 2008Malgorzata Krzystek-Korpacka PhD Abstract Background: Advanced oxidation protein products (AOPPs) are new protein markers of oxidative stress with pro-inflammatory properties, accumulated in many pathological conditions. The issue of their enhanced formation in IBD has not been addressed yet. Methods: The concentration of relative AOPPs (rAOPP; concentration of AOPPs divided by albumin level) were measured in 68 subjects with ulcerative colitis (UC), 50 subjects with Crohn's disease (CD) and 45 healthy volunteers, and related to disease phenotype, clinical and biochemical activity, and therapeutic strategy. Diagnostic utility of rAOPP was evaluated by ROC analysis. Results: In comparison with controls (1.367 ,mol/g), rAOPP were increased in inactive (1.778 ,mol/g, P = 0.053) and active (1.895 ,mol/g, P = 0.013) UC and in active (1.847 ,mol/g, P = 0.003) CD. In CD, but not UC, rAOPP correlated with disease activity (r = 0.42, P = 0.013). Significant correlations with the inflammatory/malnutrition indices-erythrocyte sedimentation rate (ESR) (r = 0.53), leukocytes (r = 0.33), platelets (r = 0.38), IL-6 (r = 0.36), and transferrin (r = ,0.35) were demonstrated in CD. In UC, rAOPP correlated only with ESR (r = 0.35) and IL-6 (r = 0.30). Instead, associations with antioxidant dismutase (r = 0.29) and catalase (r = 0.22) were observed. The diagnostic power of rAOPP in discriminating diseased from non-diseased subjects was less than that of C-reactive protein (CRP). Simultaneous determination of rAOPP and CRP did not significantly improve the power of single CRP determination. Conclusions: IBD was associated with enhanced formation of AOPP, which differed between C and UC with respect to the relationship between rAOPP and disease activity, inflammatory and antioxidant response. These differences may reflect divergent ways that oxidative stress develops in CD and UC. The diagnostic power of rAOPP was insufficient for its clinical application. (Inflamm Bowel Dis 2008) [source] Methionine sulfoxide reductase A expression is regulated by the DAF-16/FOXO pathway in Caenorhabditis elegansAGING CELL, Issue 6 2009Alicia N. Minniti Summary The methionine sulfoxide reductase system has been implicated in aging and protection against oxidative stress. This conserved system reverses the oxidation of methionine residues within proteins. We analyzed one of the components of this system, the methionine sulfoxide reductase A gene, in Caenorhabditis elegans. We found that the msra-1 gene is expressed in most tissues, particularly in the intestine and the nervous system. Worms carrying a deletion of the msra-1 gene are more sensitive to oxidative stress, show chemotaxis and locomotory defects, and a 30% decrease in median survival. We established that msra-1 expression decreases during aging and is regulated by the DAF-16/FOXO3a transcription factor. The absence of this enzyme decreases median survival and affects oxidative stress resistance of long lived daf-2 worms. A similar effect of MSRA-1 absence in wild-type and daf-2 (where most antioxidant enzymes are activated) backgrounds, suggests that the lack of this member of the methionine repair system cannot be compensated by the general antioxidant response. Moreover, FOXO3a directly activates the human MsrA promoter in a cell culture system, implying that this could be a conserved mechanism of MsrA regulation. Our results suggest that repair of oxidative damage in proteins influences the rate at which tissues age. This repair mechanism, rather than the general decreased of radical oxygen species levels, could be one of the main determinants of organisms' lifespan. [source] Total antioxidant response in patients with schizophreniaPSYCHIATRY AND CLINICAL NEUROSCIENCES, Issue 4 2006BILAL USTUNDAG md Abstract, There is a large amount of convincing data demonstrating that reactive oxygen species (ROS) are involved in initiation and development of many different forms of neuropsychiatric disorders. The levels of oxidants and antioxidants in schizophrenia have been evaluated. However, measurements of total antioxidant response (TAR) were not evaluated up to now. Therefore, the objectives of this study are to investigate plasma TAR levels in schizophrenia subtypes. A total of 76 patients with schizophrenia and 25 healthy volunteers were included in the study. Positive and Negative Syndrome Scale (SANS and SAPS, respectively) were applied to patients. TAR values were determined in the plasma of normal healthy controls and patients with schizophrenia. Plasma TAR levels of each schizophrenia subtype were significantly lower than healthy controls (P < 0.01 for disorganized, residual and undifferentiated subtypes and P < 0.01 for paranoid subtype). When intragroup comparisons were performed, paranoid subtype had higher plasma TAR levels compared to other subtypes (P < 0.01). Accordingly, as a whole group, patients with schizophrenia had lower plasma TAR levels compared to controls. Plasma TAR levels were significantly and negatively correlated with SANS scores, and duration of illness was evaluated but not related to other parameters. Consequently, the present study further emphasizes the growing consideration that free radical damage may have an important etiopathogenetic role on the development of schizophrenia and suggests that decreased plasma total antioxidant levels may be related to the progression of illness. [source] Interactions between metabolism of trace metals and xenobiotic agonists of the aryl hydrocarbon receptor in the antarctic fish Trematomus bernacchii: Environmental perspectivesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2005Francesco Regoli Abstract Although Antarctica is a pristine environment, organisms are challenged with contaminants either released locally or transported from industrialized regions through atmospheric circulation and marine food webs. Organisms from Terra Nova Bay also are exposed to a natural enrichment of cadmium, but to our knowledge, whether such environmental conditions influence biological responses to anthropogenic pollutants has never been considered. In the present study, the Antarctic rock cod (Trematomus bernacchii) was exposed to model chemicals, including polycyclic aromatic hydrocarbons (benzo[a]pyrene), persistent organic pollutants (2,3,7,8-tetrachlorodibenzo- p -dioxin [TCDD]), cadmium, and a combination of cadmium and TCDD. Analyzed parameters included chemical bioaccumulation, activity, and levels of biotransformation enzymes (cytochrome P4501A); metallothioneins and the efficiency of the antioxidant system measured as individual defenses (catalase, glutathione, glutathione reductase, glutathione S -transferases, and glutathione peroxidases); and total scavenging capacity toward peroxyl and hydroxyl radicals. Reciprocal interactions between metabolism of inorganic and organic pollutants were demonstrated. Dioxin enhanced the accumulation of cadmium, probably stored within proliferating endoplasmic reticulum, and cadmium suppressed the inducibility of cytochrome P4501A, allowing us to hypothesize a posttranscriptional mechanism as the depletion of heme group availability. Clear evidence of oxidative perturbation was provided by the inhibition of antioxidants and enhanced sensitivity to oxyradical toxicity in fish exposed to organic chemicals. Exposure to cadmium revealed counteracting responses of glutathione metabolism; however, these responses did not prevent a certain loss of antioxidant capacity toward peroxyl radicals. The pattern of antioxidant responses exhibited by fish coexposed to cadmium and TCDD was more similar to that observed for cadmium than to that observed for TCDD. The overall results suggest that elevated natural levels of cadmium in Antarctic organisms from Terra Nova Bay can limit biotransformation capability of polycyclic (halogenated) hydrocarbons, thus influencing the bioaccumulation and biological effects of these chemicals in key sentinel species. [source] Cadmium Enhances Generation of Hydrogen Peroxide and Amplifies Activities of Catalase, Peroxidases and Superoxide Dismutase in MaizeJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 1 2008P. Kumar Abstract Maize (Zea mays L. cv. 777) plants grown in hydroponic culture were treated with 50 ,m CdSO4. Growth and metabolic parameters indicative of oxidative stress and antioxidant responses were studied in leaves of plants treated with Cd. Apart from increasing lipid peroxidation and H2O2 accumulation, supply of Cd suppressed growth, fresh and dry mass of plants and decreased the concentrations of chloroplastic pigments. The activities of catalase (CAT; EC 1.11.1.6), peroxidase (POD; EC 1.11.1.7), ascorbate peroxidase (APX; EC 1.11.1.11) and superoxide dismutase (SOD; EC 1.15.1.1) were increased in plants supplied 50 ,m Cd. Localization of activities of isoforms of these enzymes (POD, APX and SOD) on native gels also revealed increase in the intensities of pre-existing bands. Stimulated activities of CAT, POD, APX and SOD in maize plants supplied excess Cd do not appear to have relieved plants from excessive generation of reactive oxygen species (ROS). It is, therefore, concluded that supply of 50 ,m Cd induces oxidative stress by increasing production of ROS despite increased antioxidant protection in maize plants. [source] Excess nickel,induced changes in antioxidative processes in maize leavesJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 6 2007Praveen Kumar Abstract Maize (Zea mays L. cv. 777) plants grown in hydroponic culture were treated with 100 µM NiSO4 (moderate nickel (Ni) excess). In addition to growth parameters, metabolic parameters representative of antioxidant responses in leaves were assessed 24 h and 3, 7, and 14 d after initiating the Ni treatment. Extent of oxidative damage was measured as accumulation of malondialdehyde and hydrogen peroxide in leaves 7 and 14 d after treatment initiation. Apart from increasing membrane-lipid peroxidation and H2O2 accumulation, excess supply of Ni suppressed plant growth and dry mass of shoots but increased dry mass of roots and decreased the concentrations of chloroplastic pigments. Excess supply of Ni, though inhibited the catalase (EC 1.11.1.6) activity, increased peroxidase (EC 1.11.1.7), ascorbate peroxidase (EC 1.11.1.11), and superoxide dismutase (EC 1.15.1.1) activities. Localization of isoforms of these enzymes (peroxidase, ascorbate peroxidase, and superoxide dismutase) on native gels also revealed increases in the intensities of pre-existing bands. Enhanced activities of peroxidase, ascorbate peroxidase, and superoxide dismutase, however, did not appear to be sufficient to ameliorate the effects of excessively generated reactive oxygen species due to excess supply of Ni. [source] Antioxidative Responses of Two Marine Microalgae During Acclimation to Static and Fluctuating Natural UV RadiationPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 6 2009Paul J. Janknegt Photoacclimation properties were investigated in two marine microalgae exposed to four ambient irradiance conditions: static photosynthetically active radiation (PAR: 400,700 nm), static PAR + UVR (280,700 nm), dynamic PAR and dynamic PAR + UVR. High light acclimated cultures of Thalassiosira weissflogii and Dunaliella tertiolecta were exposed outdoors for a maximum of 7 days. Dynamic irradiance was established by computer controlled vertical movement of 2 L bottles in a water filled basin. Immediate (<24 h), short-term (1,3 days) and long-term (4,7 days) photoacclimation was followed for antioxidants (superoxide dismutase, ascorbate peroxidase and glutathione cycling), growth and pigment pools. Changes in UVR sensitivity during photoacclimation were monitored by measuring UVR-induced inhibition of carbon assimilation under standardized UV conditions using an indoor solar simulator. Both species showed immediate antioxidant responses due to their transfer to the outdoor conditions. Furthermore, upon outdoor exposure, carbon assimilation and growth rates were reduced in both species compared with initial conditions; however, these effects were most pronounced in D. tertiolecta. Outdoor UV exposure did not alter antioxidant levels when compared with PAR-only controls in both species. In contrast, growth was significantly affected in the static UVR cultures, concurrent with significantly enhanced UVR resistance. We conclude that antioxidants play a minor role in the reinforcement of natural UVR resistance in T. weissflogii and D. tertiolecta. [source] Carotenoids in evolutionary ecology: re-evaluating the antioxidant roleBIOESSAYS, Issue 10 2009Lorenzo Pérez-Rodríguez Abstract The antioxidant role of carotenoids in the living organism was proposed as a possible basis for the honesty of carotenoid-based signals. However, recent studies have questioned the relevance of carotenoids as powerful antioxidants in vivo. Current evidence does not seem to support the "antioxidant role" hypothesis, but it does not allow us to reject it either. This paper proposes some steps to solve this controversy, such as taking a dynamic approach to antioxidant responses, designing protocols that expose individuals to oxidative challenges, analyzing tissues other than blood, and obtaining measures of antioxidant capacity and oxidative damage simultaneously. However, it should be considered that, irrespective of their antioxidant potential, carotenoids might still give information on oxidative stress levels if they are particularly sensitive to free radicals. Finally, lumping together the immunostimulatory and antioxidant roles of carotenoids should be avoided as these functions are not necessarily associated. [source] | ||||||||||||||||