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Reactive Oxygen Intermediates (reactive + oxygen_intermediate)
Selected AbstractsThe immunomodulatory effects of levamisole on the nonspecific immune system of Atlantic salmon, Salmo salar L.JOURNAL OF FISH DISEASES, Issue 6 2000V L Findlay Sea water-adapted Atlantic salmon, Salmo salar L., were given a 2-h bath in a 2.5 mg L,1 levamisole (as levamisole hydrochloride) solution in fresh-water. Following bathing, the fish were held in full salinity sea water for 2 weeks before being subjected to a number of immunological assays. Heightened activity of the nonspecific defence system was demonstrated by increases in phagocytic index, phagocytic capacity and phagocytic activity, increased levels of the reactive oxygen intermediate, superoxide anion, and an increased lytic activity of both the mucus and the serum. These results indicate that levamisole is effective in augmenting parts of the nonspecific defence system of Atlantic salmon. This is the first record of the use and efficacy of levamisole as an immunomodulator in Atlantic salmon. [source] Effect of supplemental l -ascorbyl-2-polyphosphate in enriched live food on the antioxidant defense system of Penaeus vannamei of different sizes exposed to ammonia-NAQUACULTURE NUTRITION, Issue 5 2006W.-N. WANG Abstract The effects of supplemental l -ascorbyl-2-polyphosphate (APP) in enriched live food (Artemia) on reactive oxygen intermediate (ROI) and free radical scavenging enzyme (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glutathione transferase) activities in the muscle of Penaeus vannamei of two sizes exposed to ambient ammonia-N, were investigated. Significantly, decreased ROI value was found in prawns fed on enriched Artemia compared with those fed on starved Artemia (P < 0.05); the decrease was 24% and 36%, respectively. In both size classes, the antioxidant enzyme activities in prawns fed on enriched Artemia were higher than in those fed on starved Artemia (P < 0.05). The results demonstrated that the supplementation of ascorbic acid in enriched live food (Artemia) enhanced the antioxidant capacity of prawn, increasing its defense system that may fight against environmental stress, leading to impaired ammonia toxicity. [source] Vitamin C attenuates ERK signalling to inhibit the regulation of collagen production by LL-37 in human dermal fibroblastsEXPERIMENTAL DERMATOLOGY, Issue 8 2010Hyun Jeong Park Please cite this paper as: Vitamin C attenuates ERK signalling to inhibit the regulation of collagen production by LL-37 in human dermal fibroblasts. Experimental Dermatology 2010; 19: e258,e264. Abstract:, Vitamin C is used as an anti-ageing agent because of its collagen enhancing effects. The precise cellular signalling mechanism of vitamin C is not well known. Here, we investigate the profibrotic mechanism of vitamin C against LL-37. Antimicrobial peptide LL-37 decreases collagen expression at mRNA and protein levels in human dermal fibroblasts (HDFs). The ability of LL-37 to inhibit collagen expression is dependent on phosphorylation of extracellular signal-regulated kinase (ERK). HDFs and human keloid fibroblasts were treated with vitamin C followed by 2 h of LL-37 treatment. Collagen mRNA expression and total soluble collagen production inhibited by LL-37 was enhanced by treatment with 0.5 mm vitamin C. Vitamin C also decreased intracellular reactive oxygen intermediates (ROI) levels that were increased by LL-37. Furthermore, the phosphorylation of ERK was analysed by Western blot following treatment with vitamin C and LL-37. Vitamin C turned off phosphorylation of ERK that was induced by LL-37. Ets-1 transcriptional factor, which is involved in the regulation of collagen expression by LL-37, was also inhibited by vitamin C. This study shows that vitamin C enhances collagen production by inhibiting the ERK pathway induced by LL-37. [source] TNF-, suppresses dendritic cell death and the production of reactive oxygen intermediates induced by plasma withdrawalEXPERIMENTAL DERMATOLOGY, Issue 5 2004Hong-Duck Um Abstract:, Mature dendritic cells (DCs) were generated by culturing human peripheral blood monocytes for 7 days and, then, treating them with a cytokine cocktail for 2 days. The viability of the mature DCs (Day 9) obtained was approximately 60,70%, and this gradually declined when they were recultured in X-VIVO 15 media containing 2% human plasma (40% viability after 3 days of reculture). DC death accelerated on withdrawing plasma from the culture (20% viability after 3 days). However, the addition of tumor necrosis factor-, (TNF-,) to the medium completely restored DC viability in the absence of plasma. Such a protective effect was not afforded by other cytokines, such as granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-1, (IL-1,), IL-4, IL-6 and prostaglandin E2 which are used for the maturation of DCs. These results indicate that TNF-, is specifically required to maintain the viability of mature DCs. The withdrawal of plasma rapidly (within 15 min) elevated cellular levels of reactive oxygen intermediates (ROIs), which have been proposed to regulate the ability of DCs to control inflammatory reactions. The possibility that ROIs act as mediators of DC death was eliminated by the observation that scavengers of ROIs, such as catalase, N -acetylcysteine, glutathione, failed to prolong DC life span in the absence of plasma. Interestingly, TNF-, was found to almost completely abolish the production of ROIs induced by plasma withdrawal. To summarize, our results suggest that TNF-, controls not only the inflammatory functions of DCs but also their survival. [source] The effects of N-acetylcysteine on the expression of matrix metalloproteinase-2 and tissue inhibitor of matrix metalloproteinase-2 in hepatic fibrosis in bile duct ligated ratsHEPATOLOGY RESEARCH, Issue 12 2008Arezou Rezaei Aim:, N-acetylcysteine can inhibit the formation of intracellular reactive oxygen intermediates. Cellular redox state plays a role in regulating the secretion of matrix metalloproteinase-2. We investigated the effects of N-acetylcysteine on the expression of matrix metalloproteinase-2 and tissue inhibitor of matrix metalloproteinase-2. Methods:, Bile duct ligated rats were used as a model of hepatic fibrosis. We compared the level of gene expression (using real-time reverse transcription polymerase chain reaction [RT,PCR]), liver function parameters, hepatic reactive oxygen production, lipid peroxidation and glutathione state in experimental groups. Results:, N-acetylcysteine treatment significantly improved liver function parameters including the plasma levels of aspartate aminotransferase, alkaline phosphatase, gamma-glutamyl transpeptidase and bilirubin. In addition, significant improvement of glutathione state and reactive oxygen production were observed. Hepatic lipid peroxidation was reversed by N-acetylcysteine treatment. Although N-acetylcysteine treatment did not completely normalize the increased matrix metalloproteinase-2 expression, it significantly decreased its level by 65%. N-acetylcysteine treatment also significantly decreased matrix metalloproteinase-2 activity and normalized tissue inhibitor of matrix metalloproteinase-2 expression. Conclusion:, Collectively, N-acetylcysteine showed inhibition of matrix metalloproteinase-2 expression and activity. In addition, administration of N-acetylcysteine was associated with downregulation of the expression of tissue inhibitor of matrix metalloproteinase-2 and amelioration of oxidative stress in the liver of bile duct ligated rats. [source] The effect of mineral trioxide aggregate on phagocytic activity and production of reactive oxygen, nitrogen species and arginase activity by M1 and M2 macrophagesINTERNATIONAL ENDODONTIC JOURNAL, Issue 8 2007T. M. B. Rezende Abstract Aim, To assess the influence of co-culture with mineral trioxide aggregate (MTA) on phagocytosis and the production of reactive oxygen intermediates (ROI) and nitrogen (NO) species and the arginase activity by M1 and M2 peritoneal macrophages. Methodology, Cellular viability, adherence and phagocytosis of Saccharomyces boulardii were assayed in the presence of MTA. Macrophages were stimulated with zymosan for ROI assays and with Fusobacterium nucleatum and Peptostreptococcus anaerobius and IFN- , for NO production and arginase activity, when in contact with capillaries containing MTA. Data were analysed by T, anova, Kruskall,Wallis and Mann,Whitney tests. Results, M2 macrophages displayed greater cellular viability in polypropylene tubes, greater ability to ingest yeast and smaller production of ROI and higher arginase activity when compared with M1 macrophages. Both macrophages, M1 and M2, presented similar cell adherence and NO production. The addition of bacterial preparations to macrophages interfered with NO and arginase productions. MTA did not interfere with any of the parameters measured. Conclusions, Phagocytosis and the ability of the two macrophage subtypes to eliminate microbes were not affected by MTA. [source] Interaction between leucocytes and human spermatozoa influencing reactive oxygen intermediates releaseINTERNATIONAL JOURNAL OF ANDROLOGY, Issue 2 2004Monika Fr Summary The relationship between the presence of white blood cells (WBCs) and the fertilizing potential of human semen is still an open question. It is well known that the presence of leucocytes in human semen can be related to the production of reactive oxygen intermediates (ROI). Semen samples were obtained from 15 normozoospermic men and leucocytes were isolated from heparinized blood drawn from 15 volunteers. Lucigenin and luminol-mediated chemiluminescence assays were used to determine reactive oxygen species (ROS) generation by non-activated or activated leucocytes through 12-myristate-13-acetate or N-formyl-methionyl-leucyl-phenyalanine (FMLP) before the addition of spermatozoa isolated by swim-up or Percoll procedures. All spermatozoal fractions used in this study were characterized by defining their motility, morphology and viability. The levels of ROS formation by non-activated as well as stimulated leucocytes were significantly decreased after addition of swim-up separated spermatozoa (p < 0.01). The ability to inhibit the basal chemiluminescence was of lower degree for spermatozoa isolated from 90% Percoll fractions than for swim-up sperm. However, addition of sperm cells from 47% Percoll fraction was found to increase both lucigenin and luminol signals. Moreover, the determined ROI levels changed depending on the type of inducing factor used for oxidative burst. Then, spermatozoa selected by swim-up procedure although with only slightly higher viability and morphology than sperm obtained from 90% Percoll fraction clearly exhibited much higher capacity to inhibit ROI secretion by receptor-stimulated leucocytes (FMLP-activation) than Percoll fractionated sperm. Such results may indicate that within normal semen may exist sperm subpopulations with different biochemical mechanisms controlling the interaction between spermatozoa and contaminating leucocytes. When ROI levels contained in normozoospermic semen are dependent on the WBCs activation, it seems that spermatozoa with preserved normal functional competence are able to defend themselves against leucocytes-derived ROI. Also for normozoospermic ejaculates, swim-up sperm may improve semen antioxidant characteristics when comparing with Percoll (90%) separated sperm. It may help for optimal sperm preparation when assisting to infertility treatment. [source] Dietary iron overload in the African and hepatocellular carcinomaLIVER INTERNATIONAL, Issue 6 2007Michael C. Kew Abstract Dietary iron overload occurs commonly in parts of sub-Saharan Africa. It results from the consumption of large volumes of traditional beer that is home-brewed in iron pots or drums and consequently has a high iron content. The liver becomes iron overloaded and may develop portal fibrosis or, less often, cirrhosis. A genetic predisposition to the condition has been suggested, but no putative gene has yet been identified. Although originally believed not to cause hepatocellular carcinoma, recent case,control studies have shown African Blacks with dietary iron overload to be at increased risk for the tumour and a causal association has been confirmed in an animal model. The mechanisms of iron-induced malignant transformation are yet to be fully characterised, but the close association between cirrhosis and hepatocellular carcinoma in patients with hereditary haemochromatosis and the lesser association in those with dietary iron overload, suggests that chronic necroinflammatory hepatic disease contributes to the malignant transformation. Increased hepatic iron may, however, also be directly carcinogenic. Probable mechanisms include the generation of reactive oxygen intermediates and the resultant chronic oxidative stress that damages hepatocytes and proteins, causes lipid peroxidation, and induces strand breaks, DNA unwinding, and mutations in tumour-suppressor genes and critical DNA repair genes. [source] Characterization of Arabidopsis mur3 mutations that result in constitutive activation of defence in petioles, but not leavesTHE PLANT JOURNAL, Issue 5 2008Jennifer D. Tedman-Jones Summary A screen was established for mutants in which the plant defence response is de-repressed. The pathogen-inducible isochorismate synthase (ICS1) promoter was fused to firefly luciferase (luc) and a homozygous transgenic line generated in which the ICS1:luc fusion is co-regulated with ICS1. This line was mutagenized and M2 seedlings screened for constitutive ICS1:luc expression (cie). The cie mutants fall into distinct phenotypic classes based on tissue-specific localization of luciferase activity. One mutant, cie1, that shows constitutive luciferase activity specifically in petioles, was chosen for further analysis. In addition to ICS1, PR and other defence-related genes are constitutively expressed in cie1 plants. The cie1 mutant is also characterized by an increased production of conjugated salicylic acid and reactive oxygen intermediates, as well as spontaneous lesion formation, all confined to petiole tissue. Significantly, defences activated in cie1 are sufficient to prevent infection by a virulent isolate of Hyaloperonospora parasitica, and this enhanced resistance response protects petiole tissue alone. Furthermore, cie1 -mediated resistance, along with PR gene expression, is abolished in a sid2-1 mutant background, consistent with a requirement for salicylic acid. A positional cloning approach was used to identify cie1, which carries two point mutations in a gene required for cell wall biosynthesis and actin organization, MUR3. A mur3 knockout mutant also resists infection by H. parasitica in its petioles and this phenotype is complemented by transformation with wild-type MUR3. We propose that perturbed cell wall biosynthesis may activate plant defence and provide a rationale for the cie1 and the mur3 knockout phenotypes. [source] Spatio-temporal expression of patatin-like lipid acyl hydrolases and accumulation of jasmonates in elicitor-treated tobacco leaves are not affected by endogenous levels of salicylic acidTHE PLANT JOURNAL, Issue 5 2002Sandrine Dhondt Summary We have previously isolated three tobacco genes (NtPat) encoding patatin-like proteins, getting rapidly induced during the hypersensitive response (HR) to tobacco mosaic virus, in advance to jasmonate accumulation. NtPAT enzymes are lipid acyl hydrolases that display high phospholipase A2 (PLA2) activity and may mobilize fatty acid precursors of oxylipins. Here, we performed a detailed study of NtPat gene regulation under various biotic and abiotic stresses. PLA2 activity was poorly induced in response to drought, wounding, reactive oxygen intermediates, salicylic acid (SA) or methyl-jasmonate (MJ) whereas the ethylene (ET) precursor, 1-aminocyclopropane-1-carboxylic acid (ACC), provoked a moderate induction. In contrast, PLA2 activity was strongly induced when ACC was combined with MJ, and in response to the bacterium Erwinia carotovora or to the fungus Botrytis cinerea, as well as to treatment with ,-megaspermin, a cell death-inducing protein elicitor. A simplified system based on the infiltration of ,-megaspermin into leaves was used to dissect the spatio-temporal activation of PLA2 activity with regards to the accumulation of jasmonates and to the influence of endogenous SA. NtPat -encoded PLA2 activity was rapidly induced in the infiltrated zone before the appearance of cell death and with some delay in the surrounding living cells. A massive accumulation of 12-oxo-phytodienoic and jasmonic acids occurred in the elicitor-infiltrated zone, but only low levels were detectable outside this area. A similar picture was found in SA-deficient plants, showing that in tobacco, accumulation of jasmonates is not affected by the concomitant HR-induced build-up of endogenous SA. Finally, ET-insensitive plants showed a weakened induction of PLA2 activity outside the elicitor-infiltrated tissue. [source] Effect of intermittent starvation on growth and some antioxidant indexes of Macrobrachium nipponense (De Haan)AQUACULTURE RESEARCH, Issue 5 2009Zhi-Hua Li Abstract The effect of different periods of starvation (0, 2, 4 and 8 days) followed by re-feeding on growth, feed utilization, oxygen consumption and some immune indexes [reactive oxygen intermediates (ROIs), activities of superoxide dismutase (SOD) and catalase (CAT)] was evaluated over an 18-day experimental period in shrimp Macrobrachium nipponense (De Haan) that had an initial body weight of 0.52 g. As a result of compensatory growth, indicated by an increase in specific growth rate (SGR), feeding rate (FR) and feed conversion efficiency (FCE) after re-feeding, final body weight of shrimp starved for 2 days (0.63 g) and 4 days (0.65 g) did not differ (P>0.05) from the control group (0.64 g), with feed withholding for 8 days presenting a significant lower value (0.63 g). Oxygen consumption rate (OCR) decreased during the starvation period in all groups, followed by a gradual increase to a similar (P>0.05) value than found in the control group (0.47 mg kg,1 h,1) at the end of the experiment. Although ROIs and the activity of SOD and CAT fluctuated during starvation in the feed-deprived groups, values at the termination of the experiment were comparable (P>0.05) to those found for the control group. [source] Free radical generation during the activation of hemolymph prepared from the homopteran Dactylopius coccusARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 1 2007F. García-Gil De Muñoz Abstract Superoxide anion (O,2) and nitric oxide (NO) generation in Dactylopius coccus hemolymph obtained by perfusion and activated with zymosan was studied. Activated hemolymph reduced 3-[4,5 dimethylthiazolil-2]-2,5-diphenyl tetrazolium bromide. This reduction was prevented by superoxide dismutase (SOD) indicating O,2 generation. This activity was dependent on temperature, and hemolymph incubated at 75°C lost its activity. Chromatocytes incubated with zymosan released their content and produced O,2. Activated hemolymph also produced NO and this activity was prevented in the presence of NG-nitro-L-arginine methyl ester, suggesting that nitric oxide synthase (NOS) might be present in D. coccus hemolymph. The probable source of O,2 in the D. coccus hemolymph is the anthraquinone oxidation, since commercial carminic dye produced O,2 during its oxidation by Agaricus bisporus tyrosinase. Gram+ Micrococcus luteus exposed to activated hemolymph were killed in vitro, and addition of NG-nitro-L-arginine methyl ester and D-Mannitol (a hydroxyl radical scavenger) prevented their killing. The cytotoxic effect produced by the activated hemolymph was not observed with the Gram, bacteria Serratia marcescens. These results suggest that D. coccus activated hemolymph generates reactive oxygen intermediates (ROI) and reactive nitrogen intermediates (RNI) that may limit M. luteus growth. Arch. Insect Biochem. Physiol. 65:20,28, 2007. © 2007 Wiley-Liss, Inc. [source] Microglia as immune effectors of the central nervous system: Expression of cytokines and chemokinesCLINICAL AND EXPERIMENTAL NEUROIMMUNOLOGY, Issue 2 2010Seung U. Kim Abstract Microglia, one of three glial cell types in the central nervous system (CNS), play an important role as resident immunocompetent and phagocytic cells in the CNS in the event of injury and disease. It was del Rio Hortega in 1927 who determined that microglia belong to a distinct glial cell type in the CNS, apart from astrocytes and oligodendrocytes. Since the 1970s, there has been wide recognition that microglia are immune effectors in the CNS that respond to pathological conditions and participate in the initiation and progression of neurological disorders including Alzheimer's disease, Parkinson's disease, multiple sclerosis and acquired immune deficiency syndrome dementia complex by releasing potentially cytotoxic molecules such as pro-inflammatory cytokines, reactive oxygen intermediates, proteinases and complement proteins. There is also evidence to suggest that the microglia are capable of secreting neurotrophic or neuron survival factors on activation through inflammation or injury. In the present review, the current status of knowledge on biology and immunology of microglia is reported. (Clin. Exp. Neuroimmunol. doi: 10.1111/j.1759-1961.2010.00007.x, 2010) [source] | |||||||||||||