131,275 research outputs found

    Inhibition of NOS- like activity in maize alters the expression of genes involved in H2O2 scavenging and glycine betaine biosynthesis

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    Nitric oxide synthase-like activity contributes to the production of nitric oxide in plants, which controls plant responses to stress. This study investigates if changes in ascorbate peroxidase enzymatic activity and glycine betaine content in response to inhibition of nitric oxide synthase-like activity are associated with transcriptional regulation by analyzing transcript levels of genes (betaine aldehyde dehydrogenase) involved in glycine betaine biosynthesis and those encoding antioxidant enzymes (ascorbate peroxidase and catalase) in leaves of maize seedlings treated with an inhibitor of nitric oxide synthase-like activity. In seedlings treated with a nitric oxide synthase inhibitor, transcript levels of betaine aldehyde dehydrogenase were decreased. In plants treated with the nitric oxide synthase inhibitor, the transcript levels of ascorbate peroxidase-encoding genes were down-regulated. We thus conclude that inhibition of nitric oxide synthase-like activity suppresses the expression of ascorbate peroxidase and betaine aldehyde dehydrogenase genes in maize leaves. Furthermore, catalase activity was suppressed in leaves of plants treated with nitric oxide synthase inhibitor; and this corresponded with the suppression of the expression of catalase genes. We further conclude that inhibition of nitric oxide synthase-like activity, which suppresses ascorbate peroxidase and catalase enzymatic activities, results in increased H2O2 content

    Nitric oxide of human colorectal adenocarcinoma cell lines promotes tumour cell invasion

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    The present study investigates the role of nitric oxide and the involvement of nitric oxide synthase II isoform on the invasion of human colorectal adenocarcinoma cell lines HRT-18 and HT-29. HRT-18 cells, which constitutively express nitric oxide synthase II mRNA were three-fold more invasive in a Matrigel® invasion assay than nitric oxide synthase II mRNA negative HT-29 cells. Treatment of HT-29 cells with the nitric oxide donor Deta NONOate (50 nM) as well as induction of nitric oxide synthase II mRNA and production of endogenous nitric oxide by inflammatory cytokines (IFN-γ and IL-1α) increased the invasiveness of HT-29 cells by approximately 40% and 75%, respectively. In HT-29 cells nitric oxide synthase II mRNA was also induced in co-culture with human monocytes. The invasiveness of HRT-18 cells and stimulated HT-29 cells was partly inhibited by the nitric oxide synthase II inhibitor 1400 W. These results show that nitric oxide increases the invasion of human colorectal adenocarcinoma cell lines HRT-18 and HT-29, and the involvement of nitric oxide synthase II isoform in tumour cell invasion. Therefore, the production of nitric oxide and secretion of pro-inflammatory cytokines by tumour-associated macrophages, which in turn induce nitric oxide synthase II isoform in tumour cells, promotes tumour cell invasiveness

    Adenosine preconditioning attenuates hepatic reperfusion injury in the rat by preventing the down-regulation of endothelial nitric oxide synthase

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    BACKGROUND: Previous work has suggested that in the liver, adenosine preconditioning is mediated by nitric oxide. Whether the endothelial isoform of nitric oxide synthase plays a part in this mechanism has however not yet been investigated. METHODS: Wistar rats were used (6 in each group) – Groups: (1) sham, (2) ischemia-reperfusion, (3) adenosine + ischemia-reperfusion, (4) endothelial isoform inhibitor + adenosine + ischemia-reperfusion. RESULTS: Using immunohistochemistry, this study has revealed a decrease in the expression of endothelial nitric oxide synthase following hepatic ischemia-reperfusion. This was prevented by adenosine pre-treatment. When an inhibitor of endothelial nitric oxide synthase was administered prior to adenosine pre-treatment, pre-conditioning did not occur despite normal expression of endothelial nitric oxide synthase. CONCLUSIONS: These findings suggest that adenosine attenuates hepatic injury by preventing the downregulation of endothelial nitric oxide synthase that occurs during ischemia-reperfusion

    The Major Heat Shock Proteins, Hsp70 and Hsp90, in 2-Methoxyestradiol-Mediated Osteosarcoma Cell Death Model

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    2-Methoxyestradiol is one of the natural 17β-estradiol derivatives and a potential novel anticancer agent currently being under evaluation in advanced phases of clinical trials. However, the mechanism of anticancer action of 2-methoxyestradiol has not been yet fully established. In our previous studies we have demonstrated that 2-methoxyestradiol selectively induces the expression and nuclear translocation of neuronal nitric oxide synthase in osteosarcoma 143B cells. Heat shock proteins (Hsps) are factors involved in the regulation of expression and activity of nitric oxide synthases. Herein, we chose osteosarcoma cell lines differed in metastatic potential, metastatic 143B and highly metastatic MG63.2 cells, in order to further investigate the anticancer mechanism of 2-methoxyestradiol. The current study aimed to determine the role of major heat shock proteins, Hsp90 and Hsp70 in 2-methoxyestradiol-induced osteosarcoma cell death. We focused on the implication of Hsp90 and Hsp70 in control under expression of neuronal nitric oxide synthase, localization of the enzyme, and further generation of nitro-oxidative stress. To give the insight into the role of Hsp90 in regulation of anticancer efficacy of 2-methoxyestradiol, we used geldanamycin as a potent Hsp90 inhibitor. Herein, we evidenced that inhibition of Hsp90 controls the protein expression of 2-methoxyestradiol-induced neuronal nitric oxide synthase and inhibits enzyme nuclear translocation. We propose that decreased level of neuronal nitric oxide synthase protein after a combined treatment with 2-methoxyestradiol and geldanamycin is directly associated with the accompanying upregulation of Hsp70 and downregulation of Hsp90. This interaction resulted in abrogation of anticancer efficacy of 2-methoxyestradiol by geldanamycin

    In vitro and in vivo TNFa synthesis modulation by methylguanidine, an uremic catabolyte

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    Original article can be found at: http://www.sciencedirect.com/science/journal/00243205 Copyright Elsevier Inc.We have investigated whether methylguanidine (MG), an uremic toxin, modulates the expression of the inducible nitric oxide synthase (iNOS) and nitric oxide (NO) release in vitro in LPS-induced J774 macrophages.Peer reviewe

    Low NO bioavailability in CCl(4 )cirrhotic rat livers might result from low NO synthesis combined with decreased superoxide dismutase activity allowing superoxide-mediated NO breakdown: A comparison of two portal hypertensive rat models with healthy controls

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    BACKGROUND: In cirrhotic livers, the balance of vasoactive substances is in favour of vasoconstrictors with relatively insufficient nitric oxide. Endothelial dysfunction has been documented in cirrhotic rat livers leading to a lower activity of endothelial nitric oxide synthase but this might not be sufficient to explain the low nitric oxide presence. We compared the amount of all nitric oxide synthase isoforms and other factors that influence nitric oxide bioavailability in livers of two portal hypertensive rat models: prehepatic portal hypertension and carbon tetrachloride induced cirrhosis, in comparison with healthy controls. RESULTS: Endothelial nitric oxide synthase was the solely detected isoform by Western blotting in all livers. In cirrhotic livers, the amount of endothelial nitric oxide synthase protein was lower than in healthy controls, although an overlap existed. Levels of caveolin-1 messenger RNA were within the normal range but endothelin-1 messenger RNA levels were significantly higher in cirrhotic livers (p < 0.05). A markedly lower superoxide dismutase activity was observed in cirrhotic livers as compared to healthy controls (p < 0.05). CONCLUSIONS: In contrast to prehepatic portal hypertension, cirrhotic livers had decreased endothelial nitric oxide synthase protein and enhanced endothelin-1 messenger RNA amount. We hypothesise that a vasodilator/vasoconstrictor imbalance may be further aggravated by the reduced activity of superoxide dismutase. Decreased activity allows enhanced superoxide action, which may lead to breakdown of nitric oxide in liver sinusoids

    Importance of endothelial nitric oxide synthase for the hypothermic protection of lungs against ischemia-reperfusion injury

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    ObjectivesThe hypothesis that the protective effects of mild hypothermia against the pulmonary ischemia-reperfusion injury are mediated by endothelial nitric oxide synthase was tested.MethodsEndothelial nitric oxide synthase knock-out and wild-type mice were sham operated or underwent a 1-hour occlusion of the left pulmonary hilum, followed by 5 hours of reperfusion. Temperature in the left pleural cavity during ischemia was maintained at either 36°C (normothermia) or 32°C (hypothermia). Inflammatory response (myeloperoxidase activity), endothelial barrier function (extravasation of Evans blue–labeled albumin), and endothelial nitric oxide synthase expression and phosphorylation were determined at the end of reperfusion.ResultsAfter normothermic ischemia both strains had a similar mortality (wild-type, 22.9%; knock-out, 15.4%), which was completely abolished by hypothermia. Endothelial barrier function was disturbed after normothermic ischemia in both wild-type and knock-out mice. Mild hypothermia significantly reduced pulmonary Evans blue extravasation in wild-type mice, but not in knock-out mice. Myeloperoxidase activity increased after normothermic ischemia to the same degree in both strains. This response was significantly attenuated by hypothermia in wild-type mice, but not in knock-out mice. In wild-type mice, endothelial nitric oxide synthase expression and phosphorylation were higher after hypothermic ischemia than after normothermic ischemia. No effect of ischemia on expression of inducible nitric oxide synthase was found in wild-type or knock-out mice.ConclusionHypothermic protection against pulmonary ischemia-reperfusion injury is dependent on endothelial nitric oxide synthase and is associated with increased expression and phosphorylation of endothelial nitric oxide synthase

    Inhibition of Nitric Oxide Synthase Impairs a Distinct Form of Long-Term Memory in the Honeybee, Apis mellifera

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    AbstractNitric oxide has been shown to be implicated in neural plasticity that underlies processes of learning and memory. In the honeybee, studies on the role of nitric oxide in associative olfactory learning reveal its specific function in memory formation. Inhibition of nitric oxide synthase during olfactory conditioning impairs a distinct long-term memory that is formed as a consequence of multiple learning trials. Acquisition or retrieval of memory or memory formation induced by a single learning trial is not affected by blocking of nitric oxide synthase. This finding provides a first step toward dissection of molecular mechanisms involved in memory formation, in general, and the special function of nitric oxide synthase, in particular

    Exploring the Use of Inducible Nitric Oxide Synthase to Enhance Compost Nitrogen Content

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    The goal of our research is to find and present new ways to introduce an inducible nitric oxide synthase to plants to better control nitrogen levels. We also looked at ways to introduce the synthase through compost. We are trying to answer the question of: Will the introduction of inducible nitric oxide synthase in the compost mixture increase the nutrient richness? Our results will indicate whether there are adequate mechanisms to introduce inducible nitric oxide synthase in compost mixtures. A literature review was conducted to look at previous methods used to introduce the inducible nitric oxide synthase (iNOS). We also looked at methods that are being used to accelerate the composting process. Lastly, we looked at any overlap between the synthase introduction methods and composting acceleration methods. The results indicated that compost acceleration can be accomplished by adding organic materials that are high in nitrogen, maintaining a stable and warmer temperature, and maintaining an aerobic process. When introducing the inducible nitric oxide synthase into the compost there is no prior knowledge that says the compost can process the synthase. The synthase will go to benefit the plants when it comes to their growth and resisting pathogens. If this application is successful, the composting industry will be able to market a more nitrogen heavy product to consumers, specifically farms

    Okanin, a chalcone found in the genus Bidens, and 3-penten-2-one inhibit inducible nitric oxide synthase expression via heme oxygenase-1 induction in RAW264.7 macrophages activated with lipopolysaccharide

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    Excess production of nitric oxide by activated macrophages via inducible nitric oxide synthase leads to the development of various inflammatory diseases. Heme oxygenase-1 expression via activation of nuclear factor-erythroid 2-related factor 2 inhibits nitric oxide production and inducible nitric oxide synthase expression in activated macrophages. Okanin is one of the most abundant chalcones found in the genus Bidens (Asteraceae) that is used as various folk medications in Korea and China for treating inflammation. Here, we found that okanin (possessing the α-β unsaturated carbonyl group) induced heme oxygenase-1 expression via nuclear factor-erythroid 2-related factor 2 activation in RAW264.7 macrophages. 3-Penten-2-one, of which structure, as in okanin, possesses the α-β unsaturated carbonyl group, also induced nuclear factor-erythroid 2-related factor 2-dependent heme oxygenase-1 expression, while both 2-pentanone (lacking a double bond) and 2-pentene (lacking a carbonyl group) were virtually inactive. In lipopolysaccharide-activated RAW264.7 macrophages, both okanin and 3-penten-2-one inhibited nitric oxide production and inducible nitric oxide synthase expression via heme oxygenase-1 expression. Collectively, our findings suggest that by virtue of its α-β unsaturated carbonyl functional group, okanin can inhibit nitric oxide production and inducible nitric oxide synthase expression via nuclear factor-erythroid 2-related factor 2-dependent heme oxygenase-1 expression in lipopolysaccharide-activated macrophages
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