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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of hypercholesterolemia on ischemic renal failure were evaluated in rats subjected to 60 min of left renal artery clamping and contralateral nephrectomy. One group of rats (HC) was kept on a cholesterol-supplemented diet for 3 weeks before renal injury and compared to a group fed a regular diet (ND). Two days after renal ischemia, inulin clearance (C(in), ml/min per 100 g BW) was lower in HC-rats (0.033 +/- 0.011) than in ND-rats (0.227 +/- 0.037; P < 0.01). indicating that hypercholesterolemia potentiated renal ischemic injury. Twenty-one days after renal ischemia the C(in) of HC-rats did not differ from ND-rats, suggesting that hypercholesterolemia did not limit late recovery. Since nitric oxide production is impaired in HC, L-arginine (50 mg/kg BW i.v.) was administered immediately after ischemia. Two days after ischemia, L-arg did not protect ND-rats from ischemia, while the C(in) and renal blood flow were higher in L-arg-treated HC rats than in untreated HC rats (C(in) = 0.125 +/- 0.013 rats vs. 0.033 +/- 0.011; P < 0.001) (RBF = 3.96 +/- 0.64 vs. 2.40 +/- 0.20 ml/min per 100 g BW; P < 0.05), indicating that L-arg protects HC rats from renal ischemia. The administration of D-arginine to ND rats induced a significant decrease of the C(in) and a significant increase of FE H2O, FE Na and FE K compared to the L-arginine and not treated groups. Cultures of inner medullary collecting duct cells from ND rats were resistant to 24-h hypoxia. In contrast, IMCD cell cultures from HC rats showed higher LDH release after 24-h hypoxia than normoxic cells (69.2 +/- 3.4 vs. 30.9 +/- 3.6%, P < 0.001); 1 mM L-arg added to the medium attenuated LDH release (44.3 +/- 2.4%, P < 0.01). These data demonstrate that HC predisposes renal tubular cells to hypoxic injury and L-arg protects cells of HC.
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PMID:Protective effect of L-arginine on hypercholesterolemia-enhanced renal ischemic injury. 1021 61

Myocardial infarction is linked to atherosclerosis, yet the sequence leading from silent coronary atherosclerosis to acute myocardial infarction has remained unclear. Here we show that hypercholesterolemic apolipoprotein E-/- low density lipoprotein receptor-/- mice develop not only coronary atherosclerosis but also myocardial infarction. Exposure of mice to mental stress or hypoxia led to acute ischemia, which, in a large proportion of the mice, was followed by electrocardiographic changes, leakage of troponin T, and loss of dehydrogenase from the myocardium, all indicative of acute myocardial infarction. Apoptotic death of cardiomyocytes was followed by inflammation and fibrosis in the heart. All these pathological changes could be prevented by a blocker of the endothelin type A receptor. Thus, stress elicits myocardial infarction through endothelin receptor signaling in coronary atherosclerosis caused by hypercholesterolemia.
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PMID:Myocardial infarction mediated by endothelin receptor signaling in hypercholesterolemic mice. 1035 14

Intra-aortic balloon counterpulsation (IABP) related complications in a heterogeneous group of patients who received an IABP before or after thrombolytic therapy and mechanical revascularization or in the management of refractory unstable angina and myocardial infarction related mechanical complications were evaluated prospectively. Ninety-one patients were enrolled to the study. Mean IABP duration was 4.3+/-2.4 days. While the IABP was in place, three patients (3.3%) had femoral artery emboli, four patients (4.4%) had lower extremity ischemia that resolved after the removal of the balloon, eight patients (8.8%) had groin hematoma requiring blood transfusion (< or =2 units) and four patients (4.4%) had intra-aortic balloon rupture. The relation of several risk factors to groin hematoma requiring < or =2 units blood transfusion, emboli, lower extremity ischemia and to total complications was evaluated. A chi-squared analysis showed that nadroparine use was more often complicated with emboli (P = 0.00005) and ischemic events (emboli and/or lower extremity ischemia) (three patients; 30% of nadroparine group vs. four patients; 4.9% of heparin group, P = 0.005) and hypercholesterolemia (>200 mg/dl) was more often complicated with lower extremity ischemia (P = 0.017). Forward conditional logistic regression analysis did not show any relation between the risk factors identified and emboli, lower extremity ischemia, ischemic events and groin hematoma (P>0.05), but an inverse relation was found between IABP duration and total complications (P = 0.0198). In conclusion, IABP related complications were found to remain unchanged but were not life-threatening and were inversely related to IABP duration and this suggests shorter periods of IABP use whenever possible and one must be cautious to use low molecular weight heparin in patients with an IABP in place.
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PMID:Mechanical complications of intra-aortic balloon counterpulsation. 1040 48

Endothelial cell function in all segments (arterioles, capillaries, and venules) of the microvasculature is compromised in tissues exposed to ischemia and reperfusion (I/R). This endothelial cell dysfunction is manifested as an impaired ability of arterioles to vasodilate, enhanced fluid filtration and leukocyte plugging in capillaries, and leukocyte-endothelial cell adhesion and increased protein extravasation in venules. An imbalance in the production of reactive oxygen species and nitric oxide contributes to most of these responses. The risk factors for cardiovascular disease, hypercholesterolemia, diabetes, and hypertension all appear to exacerbate the microvascular responses to I/R. A common feature of the deleterious effects of these risk factors is the enhanced oxidant stress experienced by endothelial cells, which appears to promote leukocyte-endothelial cell adhesion via transcription-independent (early response) and dependent (late response) processes. The exaggerated endothelial barrier dysfunction elicited by I/R in hypercholesterolemic animals is linked to the enhanced leukocyte recruitment, while the enhanced protein extravasation in postischemic venules of diabetic animals occurs independently of leukocyte recruitment.
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PMID:Ischemia-reperfusion: mechanisms of microvascular dysfunction and the influence of risk factors for cardiovascular disease. 1050 Oct 90

Hypercholesterolemia is a primary risk factor for atherosclerosis, coronary artery disease, and myocardial infarction. We subjected low density lipoprotein receptor-deficient (LDLr -/-) and control (wild-type) mice to 30 minutes of myocardial ischemia and 120 minutes of reperfusion. Myocardial infarction per area at risk (AAR) was noted under baseline conditions to be significantly (P<0.05) smaller in the LDLr -/- mice compared with wild-type mice (24.7+/-3. 2% and 38.8+/-4.3% of AAR, respectively). Subsequently, mice were fed a high-cholesterol diet (HCD) for 2 or 12 weeks, which resulted in significant increases in serum cholesterol levels in both LDLr -/- and wild-type groups. After 2 weeks of the HCD, the LDLr -/- mice demonstrated a significant elevation (P<0.01) in myocardial necrosis per AAR (50.2+/-5.36% of AAR) compared with the normal-diet LDLr -/- group, whereas the short-term HCD-fed wild-type mice demonstrated no significant difference from baseline. In contrast, wild-type mice fed the HCD for 12 weeks revealed a significant (P<0. 05) decrease in necrosis per AAR, which was 22.5+/-3.2% of the AAR in comparison with that in the normal-diet wild-type mice (38.8+/-4. 3% of AAR). LDLr -/- mice on the same long-term HCD showed a similar significantly (P<0.05) decreased infarct size, which was 13.2+/-4.0% of the AAR. In additional experiments, we determined that myocardial tissue total glutathione (GSH) levels were reduced after 2 weeks of the HCD and were significantly increased after 12 weeks of the HCD in the LDLr -/- mouse heart. These data suggest that short-term cholesterol feeding renders the myocardium of LDLr -/- mice more susceptible to ischemia-reperfusion injury, whereas more long-term hypercholesterolemia confers cardioprotection in the LDLr -/- mouse heart.
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PMID:Effects of hypercholesterolemia on myocardial ischemia-reperfusion injury in LDL receptor-deficient mice. 1055 25

BACKGROUND: We investigated the association of cigarette smoking with high-grade carotid artery stenosis in patients with ischemic stroke and transient ischemic attacks. METHODS: Prospectively collected data from 404 patients with focal brain ischemia were used for a cross-sectional study estimating the association between cigarette smoking and high-grade carotid artery stenosis (diagnosed by Doppler-ultrasound and defined as a luminal narrowing of > or = 70%). Cerebral ischemia patients with normal sonographic findings served as a comparison group. Multivariate logistic regression models were used for statistical tests to determine the association between smoking and high-grade carotid stenosis. Age, gender, hypertension, diabetes mellitus, hypercholesterolemia and co-existing heart disease (myocardial infarction, angina, heart failure) were considered potential confounders. RESULTS: High-grade carotid stenoses were found in 25% (n = 101) of the patients; 39% (n = 156) were classified as smokers. Smoking (odds ratio 3.6, 95% confidence interval [CI] 2.2 to 5.8), hypercholesterolemia (odds ratio 1.8; CI 1.1 to 2.8) and preexisting heart disease (odds ratio 1.7; CI 1.1 to 2.7) were significantly associated with carotid stenosis > or = 70%. The impact of smoking augmented with increasing degree of stenosis (odds ratio for stenoses > or = 80%: 4.3, CI 2.3 to 7.7), whereas the association with hypercholesterolemia, and co-existing heart disease decreased in strength for stenoses greater than 80%. Hypertension and diabetes mellitus were not found to be significantly with high-grade carotid artery stenoses. CONCLUSION: Smoking is an independent determinant of severe carotid artery stenosis in patients with focal cerebral ischemia.
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PMID:[In Process Citation] 1059 30

In an experimental model of atherosclerosis we investigated whether rabbits fed an atherogenic diet (0.25% cholesterol, 3% coconut oil) develop endothelial dysfunction accompanied with increased infarct mass compared to normal fed rabbits and, whether hypercholesterolemia would interfere with the beneficial outcome of ischemic preconditioning observed in normal rabbits. After four weeks on either a normal or an atherogenic diet, New Zealand White rabbits (n=7 in each group) were subjected to 30 min of myocardial ischemia by occlusion of a branch of the left anterior descending coronary artery (LAD) followed by 2 hours of reperfusion (infarct studies). For ischemic preconditioning experiments, LAD was additionally occluded twice for 5 min followed by 10 min reperfusion before the long-lasting (30 min) ischemia. Infarct mass was evaluated by triphenyl-tetrazolium staining. Besides the assessment of aortic endothelium-dependent function and NO-release, aortic and cardiac vessels were inspected for atherosclerotic lesions. Total cholesterol serum levels in rabbits on an atherogenic diet were significantly higher (15.3+/-2.7 mmol/L) than those on a standard diet (0.65+/-0.08 mmol/L). The aortas and heart vessels were without any histological evidence of atherosclerosis, whereas endothelial dysfunction and significantly reduced calcium-ionophore stimulated endothelial NO-release were found in isolated aortic rings of hypercholesterolemic animals. Rabbits on a standard diet showed an infarct mass (related to the area at risk) of 41+/-33%, which was reduced to 21+/-2% by ischemic preconditioning (49% decrease, p<0.05). In rabbits on an atherogenic diet, infarct mass was significantly increased to 63+/-3% (52% increase versus standard diet). Interestingly, hypercholesterolemia did not affect the beneficial influence of ischemic preconditioning; infarct mass (21+/-3%, p<0.05 vs hypercholesterolemia) was similar to rabbits on a standard diet with ischemic preconditioning. Our results show that experimental hypercholesterolemia increases infarct mass in nonpreconditioned hearts but it does not interfere with the reduction of infarct mass elicited by preconditioning. This may suggest that NO produced by the endothelium is not a prime factor in the cardioprotective mechanism of preconditioning.
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PMID:Ischemic preconditioning and infarct mass: the effect of hypercholesterolemia and endothelial dysfunction. 1074 57

Enhanced oxidant stress involved in the pathogenesis of cardiovascular (heart failure, atherosclerosis, ischemia-reperfusion injury), neurodegenerative (M. Alzheimer), metabolic (hypercholesterolemia, diabetes) and inflammatory disorders is mimicked by non-intermittent therapy with nitrovasodilators. We used this latter therapy model to study urinary 3-nitrotyrosine (n-tyr) excretion as a potential biomarker that may reflect the enhanced generation of reactive oxygen species. Namely, free or protein-bound n-tyr is formed in the organism by nitration of tyrosine (residues) via peroxynitrite (reaction product of NO&z.ccirf; and O(2)(-)&z. ccirf;). Free n-tyr content was analyzed by gas chromatography in urine obtained from healthy human subjects under a nitrite-limited diet during a two-day non-intermittent transdermal administration of glyceroltrinitrate (GTN; 0.4 mg/h) with or without vitamin C (Vit-C; 55 microg/kg/min) as antioxidant. Concomitant with the development of complete vascular tolerance (loss of dilator action), a progressive increase in urinary n-tyr excretion (up to 186+/-9 microg/day) was demonstrated in volunteers given GTN only. In contrast, when Vit-C was added, the GTN-induced increases in urinary n-tyr content were significantly suppressed (up to 130.20+/-6.91 microg/day), whereas Vit-C alone even decreased urinary n-tyr content (down to 34.00+/-5.66 microg/day), which was below control values (56.0+/-3.4 microg/day). Thus, urinary n-tyr may serve as a biomarker to detect changes in oxidant stress and thereby to evaluate the efficacy of therapeutic interventions aimed at reducing oxidant stress under various pathophysiological conditions.
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PMID:How urine analysis reflects oxidative stress--nitrotyrosine as a potential marker. 1084 22

The trafficking of leukocytes within the microcirculation is critical for normal immune surveillance of tissues. The process of leukocyte recruitment is tightly regulated by the sequential expression and activation of specific adhesion molecules on the surface of leukocytes and endothelial cells. These adhesion molecules mediate distinct steps in the recruitment of leukocytes in the microcirculation. The selectins mediate leukocyte rolling, whereas glycoproteins belonging to the integrin and immunoglobulin supergene families enable leukocytes to firmly adhere and emigrate in venules. The leukocyte-endothelial cell adhesion that is mediated by these adhesion molecules has been shown to alter the function of endothelial cells in all segments of the vasculature (ie, in arterioles, capillaries, and venules). Diseases such as ischemia-reperfusion, hypertension, and atherosclerosis exhibit vascular changes that are characteristic of acute or chronic inflammatory responses. These vascular alterations are associated with, and influenced by, changes in the avidity and density of adhesion molecules on the surface of either endothelial cells, leukocytes, or both. The activation and increased expression of these adhesion glycoproteins have been attributed to excessive production of cytokines and oxidants. The risk factors for cardiovascular disease, particularly diabetes mellitus and hypercholesterolemia, appear to sensitize the microvasculature to these inflammatory stimuli, thereby rendering tissues more vulnerable to the deleterious effects of ischemia and reperfusion. These findings raise the possibility of applying therapeutic strategies that are directed against adhesion molecules for the management of some cardiovascular diseases.
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PMID:Role of adhesion molecules in vascular regulation and damage. 1098 Nov 32

L-Arginine (Arg) is the substrate for the synthesis of nitric oxide (NO), the endothelium-derived relaxing factor essential for regulating vascular tone and hemodynamics. NO stimulates angiogenesis, but inhibits endothelin-1 release, leukocyte adhesion, platelet aggregation, superoxide generation, the expression of vascular cell adhesion molecules and monocyte chemotactic peptides, and smooth muscle cell proliferation. Arg exerts its vascular actions also through NO-independent effects, including membrane depolarization, syntheses of creatine, proline and polyamines, secretion of insulin, growth hormone, glucagon and prolactin, plasmin generation and fibrinogenolysis, superoxide scavenging and inhibition of leukocyte adhesion to nonendothelial matrix. Compelling evidence shows that enteral or parenteral administration of Arg reverses endothelial dysfunction associated with major cardiovascular risk factors (hypercholesterolemia, smoking, hypertension, diabetes, obesity/insulin resistance and aging) and ameliorates many common cardiovascular disorders (coronary and peripheral arterial disease, ischemia/reperfusion injury, and heart failure). Dietary Arg supplementation may represent a potentially novel nutritional strategy for preventing and treating cardiovascular disease.
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PMID:Arginine nutrition and cardiovascular function. 1105 97


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