Search results for "Superoxide"
showing 10 items of 462 documents
Effect of two phenanthrene alkaloids on angiotensin II-induced leukocyte-endothelial cell interactionsin vivo
2003
The present study has evaluated the effect of two phenanthrene alkaloids, uvariopsine and stephenanthrine, on angiotensin II (Ang-II)-induced leukocyte–endothelial cell interactions in vivo and the mechanisms involved in their activity. Intravital microscopy within the rat mesenteric microcirculation was used. A 60 min superfusion with 1 nM Ang-II induced a significant increase in the leukocyte–endothelial cell interactions that were completely inhibited by 1 μM uvariopsine cosuperfusion. A lower dose of 0.1 μM significantly reduced Ang-II-induced leukocyte adhesion by 75%. When Ang-II was cosuperfused with 1 and 0.1 μM stephenanthrine, Ang-II-induced leukocyte responses were significantly …
Bronchodilator and anti-inflammatory activities of glaucine:In vitrostudies in human airway smooth muscle and polymorphonuclear leukocytes
1999
Selective phosphodiesterase 4 (PDE4) inhibitors are of potential interest in the treatment of asthma. We examined the effects of the alkaloid S-(+)-glaucine, a PDE4 inhibitor, on human isolated bronchus and granulocyte function. Glaucine selectively inhibited PDE4 from human bronchus and polymorphonuclear leukocytes (PMN) in a non-competitive manner (Ki=3.4 μM). Glaucine displaced [3H]-rolipram from its high-affinity binding sites in rat brain cortex membranes (IC50∼100 μM). Glaucine inhibited the spontaneous and histamine-induced tone in human isolated bronchus (pD2∼4.5). Glaucine (10 μM) did not potentiate the isoprenaline-induced relaxation but augmented cyclic AMP accumulation by isopre…
Studies on the mechanism of photosystem II photoinhibition II. The involvement of toxic oxygen species.
1990
In a previous paper it was shown that photoinhibition of reaction centre II of spinach thylakoids was predominantly caused by the degradation of D1-protein. An initial inactivation step at the QB-site was distinguished from its breakdown. The present paper deals with the question as to whether this loss of QB-function is caused by oxygen radical attack. For this purpose the photoinhibition of thylakoids was induced at 20°C in the presence of either superoxide dismutase and catalase or the antioxidants glutathione and ascorbic acid. This resulted in comparable though not total protection of D1-protein, photochemistry and fluorescence from photoinhibition. The combined action of both the enzy…
Molecular Mechanisms of the Crosstalk Between Mitochondria and NADPH Oxidase Through Reactive Oxygen Species—Studies in White Blood Cells and in Anim…
2014
Aims: Oxidative stress is involved in the development of cardiovascular disease. There is a growing body of evidence for a crosstalk between different enzymatic sources of oxidative stress. With the present study, we sought to determine the underlying crosstalk mechanisms, the role of the mitochondrial permeability transition pore (mPTP), and its link to endothelial dysfunction. Results: NADPH oxidase (Nox) activation (oxidative burst and translocation of cytosolic Nox subunits) was observed in response to mitochondrial reactive oxygen species (mtROS) formation in human leukocytes. In vitro, mtROS-induced Nox activation was prevented by inhibitors of the mPTP, protein kinase C, tyrosine kin…
Reactive oxygen and ethylene are involved in the regulation of regurgitant-induced responses in bean plants.
2004
Summary Application of regurgitant from Leptinotarsa decemlineata Say on wound surfaces of one wounded leaf of intact bean ( Phaseolus vulgaris L.) plants resulted in activation of ethylene biosynthesis followed by an increase of both peroxidase and polyphenol oxidase activity. The aim of the present investigation was to study the source of increased oxidative enzyme activities in regurgitant-treated bean leaves and to determine if hydrogen peroxide and ethylene biosynthesis is responsible for regurgitant-induced amplification of wound responses in bean plants. As the regurgitant contained relative high activities of both peroxidase and polyphenol oxidase, there is a possibility that increa…
Vascular atherosclerotic disease: Evaluation of white blood cell rheology and metabolism after acute intravenous administration of defibrotide
1994
Defibrotide is a single-strand polydeoxyribonucleotide, obtained by controlled depolymerization of DNA extracted from mammalian organs. It stimulates vascular prostacyclin production and secretion (1-3) and enhances fibrinolysis (1, 4-6). Several clinical trials have evidentiated that defibrotide is effective in the prophylaxis of deep vein thrombosis and in the treatment of peripheral obliterative arterial disease (for a review see ref. 7). There are several reports concerning, in vitro and in vivo, the dose-dependent activity of defibrotide on the polymorphonuclear leucocytes (PMN). From these results, the molecule influences the PMN adhesivity (8, 9) and especially PMN activation, with s…
Explaining the phenomenon of nitrate tolerance.
2005
During the last century, nitroglycerin has been the most commonly used antiischemic and antianginal agent. Unfortunately, after continuous application, its therapeutic efficacy rapidly vanishes. Neurohormonal activation of vasoconstrictor signals and intravascular volume expansion constitute early counter-regulatory responses (pseudotolerance), whereas long-term treatment induces intrinsic vascular changes, eg, a loss of nitrovasodilator-responsiveness (vascular tolerance). This is caused by increased vascular superoxide production and a supersensitivity to vasoconstrictors secondary to a tonic activation of protein kinase C. NADPH oxidase(s) and uncoupled endothelial nitric oxide synthase …
Manipulation of HSP70-SOD1 Expression Modulates SH-SY5Y Differentiation and Susceptibility to Oxidative Stress-Dependent Cell Damage: Involvement in …
2023
The differentiation of neural progenitors is a complex process that integrates different signals to drive transcriptional changes, which mediate metabolic, electrophysiological, and morphological cellular specializations. Understanding these adjustments is essential within the framework of stem cell and cancer research and therapy. Human neuroblastoma SH-SY5Y cells, widely used in neurobiology research, can be differentiated into neuronal-like cells through serum deprivation and retinoic acid (RA) supplementation. In our study, we observed that the differentiation process triggers the expression of Heat Shock Protein 70 (HSP70). Notably, inhibition of HSP70 expression by KNK437 causes a dra…
Regulation of NADPH oxidase-mediated superoxide production by acetylation and deacetylation
2021
Oral treatment of apolipoprotein E-knockout (ApoE-KO) mice with the putative sirtuin 1 (SIRT1) activator resveratrol led to a reduction of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity in the heart. In contrast, the SIRT1 inhibitor EX527 enhanced the superoxide production in isolated human polymorphonuclear granulocytes. In human monocytic THP-1 cells, phorbol ester-stimulated superoxide production was enhanced by inhibitors of histone deacetylases (HDACs; including quisinostat, trichostatin A (TSA), PCI34051, and tubastatin A) and decreased by inhibitors of histone acetyltransferases [such as garcinol, curcumin, and histone acetyltransferase (HAT) Inhibitor II]. Thes…
Localized versus systemic effect of arbuscular mycorrhizal fungi on defence responses to Phytophthora infection in tomato plants
2002
Development of biological control for plant diseases is accepted as a durable and environmentally friendly alternative for agrochemicals. Arbuscular mycorrhizal fungi (AMF), which form symbiotic associations with root systems of most agricultural, horticultural and hardwood crop species, have been suggested as widespread potential bioprotective agents. In the present study the ability of two AMF (Glomus mosseae and Glomus intraradices) to induce local or systemic resistance to Phytophthora parasitica in tomato roots have been compared using a split root experimental system. Glomus mosseae was effective in reducing disease symptoms produced by P. parasitica infection, and evidence points to …