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)

Atherosclerosis involves a complex array of factors, including leukocyte adhesion and platelet vasoactive factors. Aspirin, which is used to prevent secondary complications of atherosclerosis, inhibits platelet production of thromboxane (Tx) A(2). The actions of TxA(2) as well as of other arachidonic acid products, such as prostaglandin (PG) H(2), PGF(2alpha), hydroxyeicosatetraenoic acids, and isoprostanes, can be effectively antagonized by blocking thromboxane (TP) receptors. The purpose of this study was to determine the role of platelet-derived TxA(2) in atherosclerotic lesion development by comparing the effects of aspirin and the TP receptor antagonist S18886. The effect of 11 weeks of treatment with aspirin (30 mg. kg(-1). d(-1)) or S18886 (5 mg. kg(-1). d(-1)) on aortic root atherosclerotic lesions, serum levels of intercellular adhesion molecule-1 (ICAM-1), and the TxA(2) metabolite TxB(2) was determined in apolipoprotein E-deficient mice at 21 weeks of age. Both treatments did not affect body or heart weight or serum cholesterol levels. Aspirin, to a greater extent than S18886, significantly decreased serum TxB(2) levels, indicating the greater efficacy of aspirin in preventing platelet synthesis of TxA(2). S18886, but not aspirin, significantly decreased aortic root lesions as well as serum ICAM-1 levels. S18886 also prevented the increased expression of ICAM-1 in cultured human endothelial cells stimulated by the TP receptor agonist U46619. These results indicate that inhibition of platelet TxA(2) synthesis with aspirin has no significant effect on atherogenesis or adhesion molecule levels. The effects of S18886 suggest that blockade of TP receptors inhibits atherosclerosis by a mechanism independent of platelet-derived TxA(2), perhaps by preventing the expression of adhesion molecules whose expression is stimulated by eicosanoids other than TxA(2).
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PMID:The thromboxane receptor antagonist S18886 but not aspirin inhibits atherogenesis in apo E-deficient mice: evidence that eicosanoids other than thromboxane contribute to atherosclerosis. 1089 3

Thromboxane A(2) is a potent vasoconstrictor and platelet agonist; prostacyclin is a potent platelet inhibitor and vasodilator. Altered biosynthesis of these eicosanoids is a feature of human hypercholesterolemia and atherosclerosis. This study examined whether in 2 murine models of atherosclerosis their levels are increased and correlated with the evolution of the disease. Urinary 2,3-dinor thromboxane B(2) and 2,3-dinor-6-keto prostaglandin F(1 alpha), metabolites of thromboxane and prostacyclin, respectively, were assayed in apoliprotein E (apoE)-deficient mice on chow and low-density lipoprotein receptor (LDLR)-deficient mice on chow and a Western-type diet. Atherosclerosis lesion area was measured by en face method. Both eicosanoids increased in apoE-deficient mice on chow and in LDLR-deficient mice on a high-fat diet, but not in LDLR-deficient mice on chow by the end of the study. Aspirin suppressed ex vivo platelet aggregation, serum thromboxane B(2), and 2,3-dinor thromboxane B(2), and significantly reduced the excretion of 2,3-dinor-6-keto prostaglandin F(1 alpha) in these animals. This study demonstrates that thromboxane as well as prostacyclin biosynthesis is increased in 2 murine models of atherogenesis and is secondary to increased in vivo platelet activation. Assessment of their generation in these models may afford the basis for future studies on the functional role of these eicosanoids in the evolution and progression of atherosclerosis. (Blood. 2000;96:3823-3826)
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PMID:Endogenous biosynthesis of thromboxane and prostacyclin in 2 distinct murine models of atherosclerosis. 1109 66

Aspirin reduces the incidence of thrombotic occlusive events. Classically this has been thought to be due to the platelet inhibitory action of aspirin but it has recently been shown that inflammation plays a predominant role in the initiation and progression of lesions in atherosclerosis. In humans, treatment with aspirin reduces cardiovascular risk and slows carotid plaque growth in a dose-dependent fashion. We have explored this issue in Apo E-deficient mice on a high-fat, high cholesterol diet which provided these animals with a continuous administration of 500 microg/day of acetylsalicylic acid in the drinking water. After 10 weeks of treatment, the size of the atherosclerotic lesion at the aortic sinus had reduced by 35%. At the end of the trial there were no significant changes in either plasma lipids or in the quantitative distribution among lipoproteins. Likewise, the total antioxidant status and the resistance of plasma to oxidation in vitro was similar and there was no change in the distribution of iron deposits and in the relative composition of plasma pro-oxidants and antioxidants, or in the concentration of plasma in ferritin. Therefore, it is our hypothesis that the antiinflammatory effect is responsible for the reduction in lesion size. We propose that antiinflammatory molecules which do not cause gastrointestinal complications should be tested in humans to determine long-term efficacy in the attenuation of atherosclerosis.
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PMID:The continuous administration of aspirin attenuates atherosclerosis in apolipoprotein E-deficient mice. 1120 94

In the Clopidogrel versus Aspirin in Patients at Risk of Ischaemic Events (CAPRIE) trial, clopidogrel showed a statistically significant superiority over aspirin in the prevention of ischaemic stroke, myocardial infarction and vascular death in patients with symptomatic atherosclerosis. More recently, post-hoc analysis of the data also showed that repeat hospitalization for ischaemic or bleeding events was decreased with clopidogrel compared with aspirin. Complementary analyses show that the benefit of clopidogrel over aspirin is amplified in a large population at very high risk of further atherothrombotic events (diabetics, patients with high cholesterol, and patients with previous manifestations of atherothrombosis). A potential clinically useful advantage of clopidogrel is its low propensity for adverse interaction with angiotensin-converting enzyme (ACE) inhibitors, contrary to what may be seen with aspirin, as observed in a post-hoc CAPRIE analysis. The putative aspirin-ACE inhibitor interaction is being tested prospectively in the Warfarin and Antiplatelet Therapy in Chronic Heart Failure (WATCH) trial - a randomized comparison of warfarin, clopidogrel and aspirin in patients with chronic heart failure. The good gastrointestinal tolerance of clopidogrel seen in CAPRIE has been further demonstrated in a study in healthy volunteers where there was a markedly lower gastroduodenal erosion score after 8 days' administration of clopidogrel 75 mg/day compared with aspirin 325 mg/day (p < 0.001). Following the positive findings obtained with clopidogrel plus aspirin in the Clopidogrel Aspirin Stent International Cooperative Study (CLASSICS) trial, other studies of clopidogrel plus aspirin have been initiated or are planned. These include Management of Atherothrombosis with Clopidogrel in High-risk patients (MATCH), a randomized comparison of clopidogrel plus aspirin versus clopidogrel in high-risk patients with recent stroke or transient ischaemic attack.
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PMID:Benefit of ADP receptor antagonists in atherothrombotic patients: new evidence. 1131 16

Aspirin inhibits platelet activation by irreversibly inhibiting platelet cyclooxygenase and thromboxane production, and reduces the odds of serious vascular events (stroke, myocardial infarction or vascular death) by about one quarter in a range of patients with symptomatic atherosclerosis at high risk of a subsequent event. The adenosine diphosphate (ADP) receptor antagonists clopidogrel and ticlopidine are significantly more effective than aspirin in high-risk vascular patients, further reducing the odds of serious vascular events by about 10% (95% CI 2-19%) over the benefit provided by aspirin. The ADP receptor antagonists are also associated with a significant 30% reduction in the odds of gastrointestinal haemorrhage (odds ratio 0.71, 95% CI 0.59-0.86). Ticlopidine increases the odds of skin rash and of diarrhoea by more than twofold compared with aspirin, whereas clopidogrel is associated with a one-third increase in the odds of rash and of diarrhoea. Only ticlopidine increases the odds of neutropenia compared with aspirin. There is no clear evidence as yet for the benefit of dipyridamole or an oral GP IIb/IIIa receptor antagonist as single antiplatelet agents in atherothrombotic patients. Amongst high vascular risk patients, the combination of low-dose aspirin and high-dose dipyridamole is associated with about a 10% (95% CI 0-20%) reduction in the odds of a serious vascular event. Most of this reduction is due to a 23% reduction in non-fatal stroke. The size of this estimate continues to be investigated in an ongoing study of patients with transient ischaemic attack and stroke. The combined use of aspirin and ticlopidine is markedly superior to heparin, warfarin and aspirin for reducing thrombotic complications after coronary artery stenting. Clopidogrel plus aspirin has been shown to be safer than aspirin and ticlopidine in coronary stenting, and is now under long-term evaluation in unstable angina, and other conditions in which patients are at high risk of atherothrombotic events.
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PMID:Current oral antiplatelet agents to prevent atherothrombosis. 1131 17

Degradation of ECM, particularly interstitial collagen, promotes plaque instability, rendering atheroma prone to rupture. Previous studies implicated matrix metalloproteinases (MMPs) in these processes, suggesting that dysregulated MMP activity, probably due to imbalance with endogenous inhibitors, promotes complications of atherosclerosis. We report here that the serine proteinase inhibitor tissue factor pathway inhibitor-2 (TFPI-2) can function as an MMP inhibitor. TFPI-2 diminished the ability of the interstitial collagenases MMP-1 and MMP-13 to degrade triple-helical collagen, the primary load-bearing molecule of the ECM within human atheroma. In addition, TFPI-2 also reduced the activity of the gelatinases MMP-2 and MMP-9. In contrast to the "classical" tissue inhibitors of MMPs (TIMPs), TFPI-2 expression in situ correlated inversely with MMP levels in human atheroma. TFPI-2 colocalized primarily with smooth muscle cells in the normal media as well as the plaque's fibrous cap. Conversely, the macrophage-enriched shoulder region, the prototypical site of matrix degradation and plaque rupture, stained only weakly for TFPI-2 but intensely for gelatinases and interstitial collagenases. Evidently, human mononuclear phagocytes, an abundant source of MMPs within human atheroma, lost their ability to express this inhibitor during differentiation in vitro. These findings establish a new, anti-inflammatory function of TFPI-2 of potential pathophysiological significance for human diseases, including atherosclerosis.
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PMID:Tissue factor pathway inhibitor-2 is a novel inhibitor of matrix metalloproteinases with implications for atherosclerosis. 1134 75

Because inflammatory processes may promote the development of atherosclerosis, we examined the activation of cytokine genes in rat vascular smooth muscle cells in vitro after treatment with bacterial lipopolysaccharide (LPS). Interleukin-1 (IL-1), IL-6 and tumor necrosis factor-alpha (TNF-alpha) mRNA increased in response to LPS. Activation of nuclear factor-kappaB (NF-kappaB) presumably results in NF-kappaB binding to regulatory regions of target genes and activating transcription. We therefore compared the kinetics of NF-kappaB activation, cytokine message production, and TNF-alpha secretion. Maximum active NF-kappaB was found at 30 min after the addition of LPS and decreased thereafter. Increased IL-6 mRNA was detected at 30 min, increased TNF-alpha mRNA at 60 min, and increased IL-1 mRNA at 120 min. Secretion of TNF-alpha was dependent on LPS concentration and was first detected 120 min after LPS addition. Aspirin, which has been shown to inhibit NF-kappaB activation and cytokine secretion in other cell types, did not inhibit NF-kappaB activation or TNF-alpha secretion. However, aspirin reduced the amount of both TNF-alpha and IL-6 mRNA present 30 min after LPS addition by half (P < 0.05).
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PMID:Endotoxin stimulated cytokine production in rat vascular smooth muscle cells. 1145 70

Fibrates, besides their hypolipidemic action, share alternative effects, such as decreased plasma fibrinogen and uric acid levels. Because of their complex action, additional effects have been investigated. A group of 23 patients with clinical signs of atherosclerosis and hyperlipoproteinemia was randomly allocated after a 1-month washout period and treated with either 100 mg/d of ciprofibrate or 100 mg/d of aspirin for 2 months. Patients were then treated with a combination of these two agents for the next 2 months. Ciprofibrate decreased plasma concentrations of triglycerides (-29%) and very-low-density lipoprotein cholesterol (-27%) in monotherapy and a larger reduction was observed if ciprofibrate was added to the aspirin therapy: triglycerides (-39%), very-low-density lipoprotein cholesterol (-33%), total cholesterol (-18%), low-density lipoprotein cholesterol (-17%), and increased high-density lipoprotein cholesterol (+36%). Ciprofibrate increased plasma levels of platelet-derived growth factor (PDGF) AB in both monotherapy patients (+162.9 pg/ml, +297%) and in aspirin-pretreated patients (+129.8 pg/ml, +134%); the increase of PDGF AB platelet store was significant only in aspirin-pretreated patients (+11.1 ng/ml, +51%). Aspirin in monotherapy did not modulate either plasma or platelet store of PDGF AB. Ciprofibrate did not inhibit thromboxane B 2 synthesis in platelets. Aspirin did not influence plasma thromboxane B 2 concentration at all, whereas it decreased thromboxane B 2 platelet production markedly in monotherapy (-85%) and in combination with ciprofibrate (-91%). Ciprofibrate increases PDGF AB content, which is amplified by aspirin pretreatment without correlation with its hypolipidemic action. The increase of PDGF production is suggested to participate in plaque stabilization.
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PMID:Ciprofibrate increases plasma concentration of platelet-derived growth factor AB in patients with advanced atherosclerosis and hyperlipidemia independently of its hypolipidemic effects. 1160 11

Patients with a clinical manifestation of atherothrombosis such as a recent ischaemic cerebrovascular event are at high risk of subsequent events. Atherothrombosis often reflects disseminated disease; thus, further events may occur not only in the same arterial distribution but also in other vascular beds. To achieve adequate secondary prevention in these patients, long-term antiplatelet therapy with consistent benefit across the atherothrombosis spectrum is required. In the CAPRIE (Clopidogrel versus Aspirin in Patients at Risk of Ischaemic Events) Trial, clopidogrel (clopidogrel bisulphate) was superior to acetylsalicylic acid (ASA) in reducing the combined risk of ischaemic stroke (IS), myocardial infarction (MI) or vascular death in patients with symptomatic atherosclerosis. Post hoc analyses demonstrated that the benefit of clopidogrel was amplified in high-risk patients, including patients with a history of previous ischaemic events, diabetic patients and patients with hypercholesterolaemia. The synergistic antiplatelet effect produced by using clopidogrel on top of ASA may be beneficial in high-risk patients. The benefit of dual antiplatelet therapy was recently examined in the CURE (Clopidogrel in Unstable Angina to Prevent Recurrent Events) Study, which demonstrated that long-term treatment with clopidogrel on top of standard therapy including ASA was superior to standard therapy alone in the prevention of major vascular ischaemic events in patients with unstable angina or non-Q-wave MI. The ongoing MATCH (Management of Atherothrombosis with Clopidogrel in High-risk Patients with Recent Transient Ischaemic Attack or Ischaemic Stroke) trial will evaluate the efficacy and safety of clopidogrel plus ASA versus clopidogrel alone in patients with recent transient ischaemic attack (TIA) or IS and with at least one additional risk factor. Approximately 7,600 patients will be enroled, with treatment and follow-up for each patient lasting 18 months. The primary combined efficacy endpoint will be the first occurrence of an event in the composite of IS, MI, vascular death or rehospitalization for an acute ischaemic event during the follow-up period. MATCH will explore the potential benefit of clopidogrel in high-risk stroke/TIA patients and together with CAPRIE and CURE could provide further evidence of the long-term benefit of clopidogrel in patients with major atherothrombotic manifestations.
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PMID:From CURE to MATCH: ADP receptor antagonists as the treatment of choice for high-risk atherothrombotic patients. 1180 84

Prostaglandins play important roles in the pathophysiological mechanism of action of platelets and endothelial cells in the cardiovascular system. The two isoforms of cyclo-oxygenase, respectively cyclo-oxygenase-1 and cyclo-oxygenase-2, are differently expressed in these cells. Activated platelets show a relatively large amount of cyclo-oxygenase-1, whereas endothelial cells have the gene for cyclo-oxygenase-2, the expression of which follows cell activation. In the atherosclerosis lesion, prostaglandin synthesis is mainly mediated by the inducible cyclo-oxygenase-2 expressed in macrophages/foam cells, smooth muscle cells and endothelial cells. Aspirin, a selective platelet cyclo-oxygenase-1 inhibitor still remains the most extensively studied antiplatelet agent, even though there is growing evidence that many other compounds could be valuable either in association, or alternatives in antithrombotic therapy.
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PMID:Cyclo-oxygenase-1 and cyclo-oxygenase-2 and cardiovascular system. 1182 57

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