Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Gastrointestinal side effects from nonsteroidal anti-inflammatory drugs (NSAIDs) result mainly from inhibition of the enzyme cyclooxygenase (COX)-1; it is responsible for the synthesis of prostaglandin E2, which leads to increased mucosal blood flow, increased bicarbonate secretion, and mucus production, thus protecting the gastrointestinal mucosa. In inflammation, COX-2 is induced, causing synthesis of the prostaglandins in conditions such as osteoarthritis and rheumatoid arthritis. Two NSAIDs (celecoxib and rofecoxib) with very high specificity for COX-2 and virtually no activity against COX-1 at therapeutic doses have been approved for clinical use. In trials of celecoxib and rofecoxib, only 0.02% of patients had clinically significant gastrointestinal bleeding, compared to a 1% to 2% yearly incidence of severe gastrointestinal side effects with NSAIDs. Our patient had arthritis of the hips and chronic atrial fibrillation and was on warfarin therapy for stroke prevention; less than a week after starting celecoxib therapy, gastrointestinal bleeding and hypoprothrombinemia occurred.
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PMID:Cyclooxygenase-2 inhibitor celecoxib: a possible cause of gastropathy and hypoprothrombinemia. 1100 60

Aspirin and the nonsteroidal anti-inflammatory drugs (NSAIDs) have been commercially available for decades, and their ability to reduce pain and inflammation are well known. The ability of these agents to cause adverse effects are also known, and the search for newer NSAIDs with less side effects accelerated after the two isoforms of cyclooxygenase (COX) (COX-1 and COX-2) were discovered. The selective COX-2 inhibitors seem to have equivalent efficacy, but potentially less gastrointestinal adverse effects than the traditional NSAIDs. Recent concern that the selective COX-2 inhibitors could increase cardiovascular events requires more investigation. In the meantime, aspirin continues to receive attention as a potential primary cardiovascular agent because of its antiplatelet effects and past and current clinical trials. Several trials have demonstrated that low-dose aspirin may significantly reduce the risk of myocardial infarction and other cardiovascular events. However, the benefits of aspirin need to be weighed against its primary side effect in these situations (hemorrhagic stroke). Patients at low risk for future cardiovascular events are probably not good candidates for this therapy; however, those individuals with a high risk of a future cardiovascular event may qualify for this therapy. Aspirin has also demonstrated a potential ability to reduce the risk of deep venous thrombosis and pulmonary embolism. A recent large trial of low-dose aspirin after major surgery revealed that this agent could also have some activity in the venous component of the human body. Aspirin may also have some applicability for reducing side effects of oral estrogens in men with advanced prostate cancer. Thus, it seems as if aspirin, NSAIDS, and even the selective COX-2 inhibitors may have therapeutic potential far beyond reducing pain and general inflammation. These overall observations and effects provided some of the impetus to investigate their potential ability to reduce the risk and possibly progression of a number of cancers. A few already available over-the-counter products and prescriptions seem to be receiving attention as possible anticancer agents.
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PMID:An introduction to aspirin, NSAIDs, and COX-2 inhibitors for the primary prevention of cardiovascular events and cancer and their potential preventive role in bladder carcinogenesis: part I. 1176 81

Aspirin, nonselective nonsteroidal anti-inflammatory drugs (NSAIDs), and specific cyclooxygenase-2 (COX-2) inhibitors each have distinctive effects on COX-1-mediated thromboxane biosynthesis, the major determinant of platelet aggregation. It is unclear whether these effects are associated with differences in thrombogenic risks. To compare the risk for thrombotic cardiovascular events among patients receiving rofecoxib, nonselective NSAIDs, and placebo, cardiovascular safety was assessed in 5,435 participants in 8 phase IIB/III osteoarthritis trials. The median treatment exposure was 31/2 months. The primary end point assessed was the risk of any arterial or venous thrombotic cardiovascular adverse event (AE). A second analysis assessed differences in the Anti-Platelet Trialists' Collaboration (APTC) events, a cluster end point that consists of the combined incidence of (1) cardiovascular, hemorrhagic, and unknown death; (2) myocardial infarction; and (3) cerebrovascular accident. Similar rates of thrombotic cardiovascular AEs were reported with rofecoxib, placebo, and comparator nonselective NSAIDs (ibuprofen, diclofenac, or nabumetone). In trials that compared rofecoxib with NSAIDs, the incidence of thrombotic cardiovascular AEs was 1.93/100 patient-years in the rofecoxib treatment group compared with 2.27/100 patient-years in the combined nonselective NSAID group. In trials that compared rofecoxib with placebo, the incidence of thrombotic cardiovascular AEs was 2.71/100 patient-years in the rofecoxib group compared with 2.57/100 patient-years in the placebo group. Consistent with the risks of cardiovascular AEs, similar rates of APTC events were reported with rofecoxib, placebo, and comparator nonselective NSAIDs. Thus, in the rofecoxib osteoarthritis development program, there was no difference between rofecoxib, comparator nonselective NSAIDs, and placebo in the risks of cardiovascular thrombotic events.
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PMID:Comparison of cardiovascular thrombotic events in patients with osteoarthritis treated with rofecoxib versus nonselective nonsteroidal anti-inflammatory drugs (ibuprofen, diclofenac, and nabumetone). 1195 Apr 38

Inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 are expressed in vascular smooth muscle cells stimulated with interleukin-1beta (IL-1beta), resulting in the production of nitric oxide (NO) and prostaglandins (PGs) such as PGI2. The iNOS and COX-2 proteins and their mRNA expressions in cultured vascular smooth muscle cells isolated from 6-7 week-old stroke-prone spontaneously hypertensive rats (SHRSP) were compared with those in the cells isolated from age-matched normotensive Wistar Kyoto rats (WKY). The IL-1beta-induced NO production and iNOS expression in vascular smooth muscle cells of SHRSP were significantly lower than those in cells of WKY. Similarly, PGI2 production and COX-2 expression were significantly lower in vascular smooth muscle cells of SHRSP than WKY, whereas there was no difference in the COX-1 expression. There were no significant differences in iNOS and COX-2 mRNA expressions between the two strains, suggesting that these protein expression may be reduced at the post-transcriptional level in cells of SHRSP. These results further suggest that the reduction of iNOS and COX-2 expressions in vascular smooth muscle cells may have relevance to the pathophysiology in SHRSP.
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PMID:Reduced expressions of inducible nitric oxide synthase and cyclooxygenase-2 in vascular smooth muscle cells of stroke-prone spontaneously hypertensive rats. 1185 30

The functional significance of cyclooxygenases (COX-1 and -2), the key enzymes that convert arachidonic acid (AA) to prostaglandins (PGs) in brain, is unclear, although they have been implicated in cellular functions and in some neurologic disorders, including stroke, epilepsy, and Alzheimer's disease. Recent evidence that COX-2 is expressed in postsynaptic dendritic spines (which are specialized structures involved in synaptic signaling) and is regulated by synaptic activity implies participation of COX-2 in neuronal plasticity. However, direct evidence is lacking. Here we demonstrate that selective COX-2 inhibitors significantly reduced postsynaptic membrane excitability, back-propagating dendritic action potential-associated Ca2+ influx, and long-term potentiation (LTP) induction in hippocampal dentate granule neurons, while a COX-1 inhibitor is ineffective. All of these actions were effectively reversed by exogenous application of PGE2 but not of PGD2 or PGF(2alpha). Our results indicate that COX-2-generated PGE2 regulates membrane excitability and long-term synaptic plasticity in hippocampal perforant path-dentate gyrus synapses.
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PMID:Cyclooxygenase-2 regulates prostaglandin E2 signaling in hippocampal long-term synaptic plasticity. 1203 88

Reduction of plasma low density lipoprotein (LDL) levels is associated with a reduced risk of myocardial infarction, stroke, and death. Some of this clinical benefit may be derived from an improvement in endothelium-dependent vasodilation. In the present study, we examined the effects of LDL reduction on cyclooxygenase (COX) activity and prostacyclin (PGI2) production. Human umbilical vein endothelial cells exposed to reduced concentrations of LDL demonstrated increased PGI2 production in a dose-dependent manner (from 0.75+/-0.2 to 2.6+/-0.2 ng/mL, P<0.0001). This alteration in PGI2 production did not result from LDL-induced changes in PGI2 synthase expression. However, selective inhibition of COX-2, but not COX-1, blocked PGI2 production under low cholesterol conditions. Addition of exogenous cholesterol induces dose-dependent reductions in endothelial COX-2 expression as measured by reverse transcription-polymerase chain reaction and by Western blotting. Pretreatment of cells with actinomycin D, a transcription inhibitor, reduced COX-2-derived PGI2 production by 45.9% (from 0.55+/-0.09 to 0.25+/-0.08 ng/mL). Taken together, these observations indicate that endothelial PGI2 production is regulated by cholesterol at the transcriptional level and that cholesterol-sensitive transcriptional pathways that regulate COX-2 expression are present in vascular tissue.
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PMID:Cyclooxygenase-2-dependent prostacyclin formation is regulated by low density lipoprotein cholesterol in vitro. 1206 8

Cyclooxygenase (COX) is crucial in inflammation; COX-1 is constitutional, and COX-2 is inducible. In this study, neurological function and infarct volume were evaluated at 24 h after permanent endovascular middle cerebral artery occlusion (MCAO) in both COX-1-gene knockout (homozygous or heterozygous) and wide-type mice. Similar infarct volumes and neurological deficits were seen among mice of different genotypes. There was no difference among the groups in arterial blood pressure and regional cerebral blood flow during the first 30 min of ischemia. Our results failed to confirm the harmful effect of losing COX-1 activity due to gene knockout in a permanent endovascular MCAO mouse stroke model.
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PMID:Cyclooxygenase-1 gene knockout does not alter middle cerebral artery occlusion in a mouse stroke model. 1221 34

Prostaglandins (PGs) originate from the degradation of membranar arachidonic acid by cyclooxygenases (COX-1 and COX-2). The prostaglandin actions in the nervous system are multiple and have been suggested to play a significant role in neurodegenerative disorders. Some PGs have been reported to be toxic and, interestingly, the cyclopentenone PGs have been reported to be cytoprotective at low concentration and could play a significant role in neuronal plasticity. They have been shown to be protective against oxidative stress injury; however, the cellular mechanisms of protection afforded by these PGs are still unclear. It is postulated that the cascade leading to neuronal cell death in acute and chronic neurodegenerative conditions, such as cerebral ischemia and Alzheimer's disease, would be mediated by free radical damage. We tested the hypothesis that the neuroprotective action of cyclopentanone could be caused partially by an induction of heme oxygenase 1 (HO-1). We and others have previously reported that modulation of HO total activity may well have direct physiological implications in stroke and in Alzheimer's disease. HO acts as an antioxidant enzyme by degrading heme into iron, carbon monoxide, and biliverdin that is rapidly converted into bilirubin. Using mouse primary neuronal cultures, we demonstrated that PGs of the J series induce HO-1 in a dose-dependent manner (0, 0.5, 5, 10, 20, and 50 micro g/ml) and that PGJ(2) and dPGJ(2) were more potent than PGA(2), dPGA(2), PGD(2), and PGE(2). No significant effects were observed for HO-2 and actin expression. In regard to HO-3 expression found in rat, with its protein deducted sequence highly homologous to HO-2, no detection was observed in HO-2(-/-) mice, suggesting that HO-3 protein would not be present in mouse brain. We are proposing that several of the protective effects of PGJ(2) could be mediated through beneficial actions of heme degradation and its metabolites. The design of new mimetics based on the cyclopentenone structure could be very useful as neuroprotective agents and be tested in animal models of stroke and Alzheimer's disease.
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PMID:Regulation of heme oxygenase expression by cyclopentenone prostaglandins. 1270 76

Arachidonic acid metabolism plays an important role in acute ischemic syndromes affecting the coronary or cerebrovascular territory, as reflected by biochemical measurements of eicosanoid biosynthesis and the results of inhibitor trials in these settings. Two cyclooxygenase (COX)-isozymes have been characterized, COX-1 and COX-2, that differ in terms of regulatory mechanisms of expression, tissue distribution, substrate specificity, preferential coupling to upstream and downstream enzymes, and susceptibility to inhibition by the extremely heterogeneous class of COX-inhibitors. Although the role of platelet COX-1 in acute coronary syndromes and ischemic stroke is firmly established through approximately 20 years of thromboxane metabolite measurements and aspirin trials, the role of COX-2 expression and inhibition in atherothrombosis is substantially uncertain, because the enzyme was first characterized in 1991 and selective COX-2 inhibitors became commercially available only in 1998. In this review, we discuss the pattern of expression of COX-2 in the cellular players of atherothrombosis, its role as a determinant of plaque "vulnerability," and the clinical consequences of COX-2 inhibition. Recent studies from our group suggest that variable expression of upstream and downstream enzymes in the prostanoid biosynthetic cascade may represent important determinants of the functional consequences of COX-2 expression and inhibition in different clinical settings.
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PMID:Cyclooxygenase-2 expression and inhibition in atherothrombosis. 1459 54

The cyclooxygenases COX-1 and COX-2 catalyze the first committed step of prostaglandin synthesis from arachidonic acid. Previous studies in rodent stroke models have shown that the inducible COX-2 isoform promotes neuronal injury, and the administration of COX-2 inhibitors reduces infarct volume. We investigated the function of PGE2, a principal prostaglandin product of COX-2 enzymatic activity, in neuronal survival in cerebral ischemia. PGE2 exerts its downstream effects by signaling through a class of four distinct G-protein-coupled EP receptors (for E-prostanoid: EP1, EP2, EP3, and EP4) that have divergent effects on cAMP and phosphoinositol turnover and different anatomical distributions in brain. The EP2 receptor subtype is abundantly expressed in cerebral cortex, striatum, and hippocampus, and is positively coupled to cAMP production. In vitro studies of dispersed neurons and organotypic hippocampal cultures demonstrated that activation of the EP2 receptor was neuroprotective in paradigms of NMDA toxicity and oxygen glucose deprivation. Pharmacologic blockade of EP2 signaling by inhibition of protein kinase A activation reversed this protective effect, suggesting that EP2-mediated neuroprotection is dependent on cAMP signaling. In the middle cerebral artery occlusion-reperfusion model of transient forebrain ischemia, genetic deletion of the EP2 receptor significantly increased cerebral infarction in cerebral cortex and subcortical structures. These studies indicate that activation of the PGE2 EP2 receptor can protect against excitotoxic and anoxic injury in a cAMP-dependent manner. Taken together, these data suggest a novel mechanism of neuroprotection mediated by a dominant PGE2 receptor subtype in brain that may provide a target for therapeutic intervention.
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PMID:Neuroprotective function of the PGE2 EP2 receptor in cerebral ischemia. 1471 58


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