UMLS:C0004153 - FACTA Search

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Query: UMLS:C0004153 (atherosclerosis)
77,401 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

At high concentrations, free radicals and radical-derived, nonradical reactive species are hazardous for living organisms and damage all major cellular constituents. At moderate concentrations, however, nitric oxide (NO), superoxide anion, and related reactive oxygen species (ROS) play an important role as regulatory mediators in signaling processes. Many of the ROS-mediated responses actually protect the cells against oxidative stress and reestablish "redox homeostasis." Higher organisms, however, have evolved the use of NO and ROS also as signaling molecules for other physiological functions. These include regulation of vascular tone, monitoring of oxygen tension in the control of ventilation and erythropoietin production, and signal transduction from membrane receptors in various physiological processes. NO and ROS are typically generated in these cases by tightly regulated enzymes such as NO synthase (NOS) and NAD(P)H oxidase isoforms, respectively. In a given signaling protein, oxidative attack induces either a loss of function, a gain of function, or a switch to a different function. Excessive amounts of ROS may arise either from excessive stimulation of NAD(P)H oxidases or from less well-regulated sources such as the mitochondrial electron-transport chain. In mitochondria, ROS are generated as undesirable side products of the oxidative energy metabolism. An excessive and/or sustained increase in ROS production has been implicated in the pathogenesis of cancer, diabetes mellitus, atherosclerosis, neurodegenerative diseases, rheumatoid arthritis, ischemia/reperfusion injury, obstructive sleep apnea, and other diseases. In addition, free radicals have been implicated in the mechanism of senescence. That the process of aging may result, at least in part, from radical-mediated oxidative damage was proposed more than 40 years ago by Harman (J Gerontol 11: 298-300, 1956). There is growing evidence that aging involves, in addition, progressive changes in free radical-mediated regulatory processes that result in altered gene expression.
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PMID:Free radicals in the physiological control of cell function. 1177 9

Restenosis, a frequent complication of coronary angioplasty, is associated with increased superoxide (O2*(-)) production. Although the molecular identity of the responsible oxidase is unclear, an NAD(P)H oxidase appears to be involved. In smooth muscle, p22phox and 2 homologues of gp91phox, nox1 and nox4, are expressed, whereas fibroblasts contain gp91phox. To begin investigating the possibility that these oxidase components might contribute to the increased O2*(-) that accompanies neointimal formation, we measured their expression after balloon injury of the rat carotid artery. The increase in O2*(-) production 3 to 15 days after surgery was not due to inflammatory cell infiltration but appeared to be derived from medial and neointimal smooth muscle cells and adventitial fibroblasts. Nox1 and p22phox mRNAs were increased 2.7- and 3.6-fold, respectively, at day 3 after injury and remained elevated for 15 days. gp91Phox was increased 7 to 15 days after injury, and nox4 expression was increased 2-fold, but only at day 15 after surgery. These results confirm and extend our previous in vitro data and suggest that in the vasculature, the nox-based NAD(P)H oxidases serve different functions. This dynamic regulation of oxidase components may be critical to smooth muscle phenotypic modulation in restenosis and atherosclerosis.
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PMID:Upregulation of Nox-based NAD(P)H oxidases in restenosis after carotid injury. 1178 53

Superoxide (O2*-) in arteries may contribute to atherosclerosis in part by inactivation of nitric oxide. We hypothesized that regression of atherosclerosis in nonhuman primates is associated with a decrease in vascular NAD(P)H oxidase, decreased O2*- levels, and improved endothelium-dependent relaxation. Cynomolgus monkeys (n=28) were fed an atherogenic diet for 47+/-10 (mean+/-SE) months. In carotid arteries (containing advanced lesions), femoral arteries (moderate lesions), and saphena arteries (minimal lesions), we examined O2*- levels and vasomotor function. Compared with vessels from normal monkeys (n=8), O2*- levels (measured by lucigenin-enhanced chemiluminescence) were 3.3-fold higher in carotid, 1.7-fold higher in femoral, and not different in saphena arteries from atherosclerotic monkeys. Dihydroethidium staining also demonstrated increased O2*- levels throughout the vessel wall in femoral and carotid arteries from atherosclerotic monkeys. Components of the NAD(P)H oxidase (p22(phox) and p47(phox)) were increased in atherosclerotic arteries, and immunohistochemistry demonstrated colocalization primarily to areas of macrophage infiltration. Relaxation to acetylcholine was impaired in carotid and femoral, but not saphena, arteries from atherosclerotic monkeys. After 8 months of regression diet (n=9), serum cholesterol decreased to normal, and O2*- levels (basal and NAD(P)H-stimulated), as well as expression of NAD(P)H oxidase, returned toward normal. Relaxation to acetylcholine improved in femoral arteries, but not in the more diseased carotid arteries. We conclude that, in a primate model of moderately severe atherosclerosis and regression of atherosclerosis, changes in endothelial function are inversely related to O2*- and NAD(P)H oxidase levels. Reduction in vascular O2*- during regression of atherosclerosis may contribute to improvement in vasomotor function.
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PMID:Regression of atherosclerosis in monkeys reduces vascular superoxide levels. 1186 15

Common vascular disease states including diabetes, hypertension and atherosclerosis are associated with endothelial dysfunction, characterised by reduced bioactivity of nitric oxide (NO). Loss of the vasculoprotective effects of NO contributes to disease progression, but the mechanisms underlying endothelial dysfunction remain unclear. Increased superoxide production in animal models of vascular disease contributes to reduced NO bioavailability, endothelial dysfunction and oxidative stress. In human blood vessels, the NAD(P)H oxidase system is the principal source of superoxide, and is functionally related to clinical risk factors and systemic endothelial dysfunction. Furthermore, the C242T polymorphism in the NAD(P)H oxidase p22phox subunit is associated with significantly reduced superoxide production in patients carrying the 242T allele, suggesting a role for genetic variation in modulating vascular superoxide production. In vessels from patients with diabetes mellitus, endothelial dysfunction, NAD(P)H oxidase activity and protein subunits are significantly increased compared with matched non-diabetic vessels. Furthermore, the vascular endothelium in diabetic vessels is a net source of superoxide rather than NO production, due to dysfunction of endothelial NO synthase (eNOS). This deficit is dependent on the eNOS cofactor, tetrahydrobiopterin, and is in part mediated by protein kinase C signalling. These studies suggest an important role for both the NAD(P)H oxidases and endothelial NOS in the increased vascular superoxide production and endothelial dysfunction in human vascular disease states.
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PMID:Mechanisms of superoxide production in human blood vessels: relationship to endothelial dysfunction, clinical and genetic risk factors. 1251 89

Angiotensin II has been shown to participate in both physiological processes, such as sodium and water homeostasis and vascular contraction, and pathophysiological processes, including atherosclerosis and hypertension. The effects of this molecule on vascular tissue are mediated at least in part by the modification of the redox milieu of its target cells. Angiotensin II has been shown to activate the vascular NAD(P)H oxidase(s) resulting in the production of reactive oxygen species, namely superoxide and hydrogen peroxide. In this article, we review what is known about the molecular steps that link angiotensin II and its receptor to production of reactive oxygen species and subsequent redox-mediated events, focusing on the structural and functional properties of the vascular NAD(P)H oxidases and their downstream mediators. As such, we provide a framework linking angiotensin II to crucial vascular pathologies, such as hypertension, atherosclerosis, and restenosis after angioplasty, by means of the NAD(P)H-dependent oxidases and their effector molecules.
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PMID:NAD(P)H oxidase-derived reactive oxygen species as mediators of angiotensin II signaling. 1257 39

1. Reactive oxygen species (ROS) are known to be involved in the progression of various cardiovascular diseases. One source of ROS is activated neutrophils, which can release superoxide anion radicals and hydrogen peroxide by membrane-bound NAD(P)H oxidases. These ROS not only destroy bacteria, but may also affect mammalian tissue. In addition, hydrogen peroxide serves as a substrate for myeloperoxidase, an enzyme that is released by activated neutrophils during inflammatory processes, as seen, for instance, in reperfusion injury and atherosclerosis. Myeloperoxidase catalyses the oxidation of chloride by hydrogen peroxide, yielding hypochlorite, an extremely potent oxidant. 2. The purpose of the present study was to evaluate the effects of hypochlorite on a variety of receptor-dependent processes in rat isolated left atria and rat thoracic aorta and to compare these results with the phenomena observed after incubation with hydrogen peroxide. 3. In the presence of hypochlorite (300 micro mol/L), the positive inotropic response of alpha1-adrenoceptor stimulation by methoxamine (300 micro mol/L) was converted into a negative inotropic response. In contrast, the positive inotropic effects of the beta1/beta2-adrenoceptor agonist isoprenaline (3 micro mol/L) and endothelin (ET)-1 (100 nmol/L) remained largely unaffected. 4. The inversion of alpha1-adrenoceptor-mediated inotropy was not obtained in the presence of hydrogen peroxide (500 micro mol/L). Hydrogen peroxide did not affect the positive inotropic response of isoprenaline, but it completely abolished the inotropic effect of ET-1. 5. The effect of cardiac M2-receptor stimulation was studied in the presence of hypochlorite and hydrogen peroxide. The negative inotropic response to acetylcholine (ACh) was significantly enhanced after hypochlorite incubation compared with control. 6. In the rat thoracic aorta, endothelial function, evaluated by means of ACh-induced vasodilation, was completely abolished in the presence of hypochlorite (100 micro mol/L), but remained unaffected by treatment with the same concentration of hydrogen peroxide. 7. From these data, we conclude that hypochlorite exerts more toxic properties than its precursor hydrogen peroxide, leading to substantial physiological alterations in cardiac and vascular tissue.
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PMID:Effects of hypochlorite and hydrogen peroxide on cardiac autonomic receptors and vascular endothelial function. 1268 Aug 42

Excessive production of reactive oxygen species (ROS) occurs in many diseases and oxidation may be a common disease mechanism generally. The original "oxidation hypothesis" concerning the pathogenesis of atherosclerosis was posited in the context of the putative central role of oxidized LDL in the process. Atherosclerosis has three major characteristic features: inflammation with accumulation of T-cells and, in particular, monocytes, which become lipid rich foam cells; remodeling of the arterial wall; and the non-random localization of lesions to areas of disturbed flow or of low shear stress. The evidence is reviewed that each of these characteristics can be attributed to excessive ROS, which are derived from cellular oxidases, especially, the NAD(P)H oxidases. This expanded concept of the central role of oxidation in the pathogenesis of atherosclerosis has led to a renewed and intense interest in the potential role of antioxidants in therapy. The vascular protective effects of existing drugs such as statins and ACE inhibitors that are not related to serum lipid alterations are attributed to their indirect but effective roles as antioxidants. These data as well as evidence that newly developed antioxidant drugs show promise, not only in experimental animals but also clinically, are reviewed.
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PMID:The Jeremiah Metzger Lecture. Pathogenesis of atherosclerosis: redox as a unifying mechanism. 1281 26

Activation of vascular NAD(P)H oxidases and the production of reactive oxygen species (ROS) by these enzyme systems are common in cardiovascular disease. In the past several years, a new family of NAD(P)H oxidase subunits, known as the non-phagocytic NAD(P)H oxidase (NOX) proteins, have been discovered and shown to play a role in vascular tissues. Recent studies make clearer the mechanisms of activation of the endothelial and vascular smooth muscle NAD(P)H oxidases. ROS produced following angiotensin II-mediated stimulation of NAD(P)H oxidases signal through pathways such as mitogen-activated protein kinases, tyrosine kinases and transcription factors, and lead to events such as inflammation, hypertrophy, remodeling and angiogenesis. Studies in mice that are deficient in p47(phox) and gp91(phox) (also known as NOX2) NAD(P)H oxidase subunits show that ROS produced by these oxidases contribute to cardiovascular diseases including atherosclerosis and hypertension. Recently, efforts have been devoted to developing inhibitors of NAD(P)H oxidases that will provide useful experimental tools and might have therapeutic potential in the treatment of human diseases.
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PMID:The vascular NAD(P)H oxidases as therapeutic targets in cardiovascular diseases. 1296 72

Vascular NAD(P)H oxidase-derived reactive oxygen species (ROS) such as hydrogen peroxide (H2O2) have emerged as important molecules in the pathogenesis of atherosclerosis, hypertension, and diabetic vascular complications. Additionally, myeloperoxidase (MPO), a transcytosable heme protein that is derived from leukocytes, is also believed to play important roles in the above-mentioned inflammatory vascular diseases. Previous studies have shown that MPO-induced vascular injury responses are H2O2 dependent. It is well known that MPO can use leukocyte-derived H2O2; however, it is unknown whether the vascular-bound MPO can use vascular nonleukocyte oxidase-derived H2O2 to induce vascular injury. In the present study, ANG II was used to stimulate vascular NAD(P)H oxidases and increase their H2O2 production in the vascular wall, and vascular dysfunction was used as the vascular injury parameter. We demonstrated that vascular-bound MPO has sustained activity in the vasculature. MPO could use the vascular NAD(P)H oxidase-derived H2O2 to produce hypochlorus acid (HOCl) and its chlorinating species. More importantly, MPO derived HOCl and chlorinating species amplified the H2O2-induced vascular injury by additional impairment of endothelium-dependent relaxation. HOCl-modified low-density lipoprotein protein (LDL), a specific biomarker for the MPO-HOCl-chlorinating species pathway, was expressed in LDL and MPO-bound vessels with vascular NAD(P)H oxidase-derived H2O2. MPO-vascular NAD(P)H oxidase-HOCl-chlorinating species may represent a common pathogenic pathway in vascular diseases and a new mechanism involved in exacerbation of vascular diseases under inflammatory conditions.
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PMID:Interaction of myeloperoxidase with vascular NAD(P)H oxidase-derived reactive oxygen species in vasculature: implications for vascular diseases. 1461 14

Oxidative stress contributes to the pathogenesis of atherosclerosis. p22phox-based NAD(P)H oxidases exist in the vessel wall, acting as important superoxide-generating systems in the vasculature. Some studies have identified reduced atherosclerosis in the presence of the C242T CYBA polymorphism, whereas others have not. Because vascular p22phox is identical to neutrophil p22phox, we studied the association between the C242T, A640G, and -930A/G CYBA polymorphisms and the quantity of superoxide produced from neutrophils isolated from healthy adults to determine if these polymorphisms had any functional impact on NADPH oxidase function. Neutrophils were isolated from 90 subjects by Percoll density gradient centrifugation. Genotypes were determined by polymerase chain reaction (PCR) and restriction mapping, as well as real-time PCR. The oxidative burst was stimulated with phorbol 12-myristate 13-acetate. Superoxide was quantified using the superoxide dismutase inhibitable oxidation of the spin probe hydroxylamine 1-hydroxy-3-carboxy-pyrrolidine, detected by electron paramagnetic resonance. Superoxide production was significantly affected by the C242T polymorphism, being 8.7+/-0.7, 7.9+/-0.6, and 5.9+/-1.2 micromol/L per minute per 10(6) neutrophils for the C242T CC, CT, and TT genotypes, respectively (P<0.05). In contrast, the A640G and the -930A/G polymorphisms did not alter the neutrophil respiratory burst. Phagocytic respiratory burst activity in homozygous individuals with the T allele of the C242T CYBA polymorphism is significantly lower than of wild-type carriers and heterozygous individuals. Because p22phox exists in both the neutrophil and vessel wall, vascular oxidative stress is likely diminished in individuals with this polymorphism.
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PMID:C242T CYBA polymorphism of the NADPH oxidase is associated with reduced respiratory burst in human neutrophils. 1507 63

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