Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have previously shown an increase in platelet-to-endothelial cell adhesion in microvessels of spontaneously hypertensive rats (SHR) during the established stage of hypertension (12 weeks). The objective of the current study was to determine if the platelet-to-endothelial cell interaction would be altered in the early developmental phase of hypertension. Male weanling (3 weeks old) SHRs (n=6) and age matched normotensive Wistar-Kyoto (WKY) rats (n=6) were used to study platelet thrombus formation. Intravascular fluorescein isothiocyanate tagged to bovine serum albumin was activated with 450-490 nm light to induce thrombus formation in microvessels. Plasma concentrations of von Willebrand factor (vWF), fibrinogen and fibronectin (FN) were measured in rats during both early (3 week) and established stages of hypertension development. Thrombus initiation time in both arterioles (847+/-85 sec) and venules (222+/-40 sec) of young SHRs was significantly shorter (p<0.05) than in arterioles (1270+/-88 sec) and venules (630+/-72 sec) of age matched WKY rats respectively. After thrombus appearance, however, overall time for vessel occlusion in arterioles (2590+/-90 sec) and venules (935+/-131 sec) of SHRs was not different compared to that in arterioles (2650+/-191 sec) and venules (1240+/-93 sec) of age matched WKY rats. The plasma concentration of FN was increased (p<0.05) in both the young (0.9+/-0.1 mg/ml) and mature (1.1+/-0.2 mg/ml) hypertensive rats (n=5) compared to that in young (0.6+/-0.03 mg/ml) and mature (0.5+/-0.1 mg/ml) WKY rats (n=5), while fibrinogen content (3.6 +/-0.3 mg/ml) was elevated (p<0.05) only in mature SHRs (n=5) compared to that (2.7+/-0.02 mg/ml) in age matched WKY rats (n=5). The plasma concentration of vWF was similar to that of controls in either age group of hypertensive animals. These results suggest that changes in platelet-to-endothelial cell interactions occur in the early phase of genetic hypertension development in rats, and appears to result from alteration of plasma concentration of adhesion proteins.
 ...
PMID:Platelet thrombus formation in microvessels of young spontaneously hypertensive rats. 981 10

1. The preventive effects of exercise and L-arginine intake on hypertension and thrombosis in stroke-prone spontaneously hypertensive rats (SHRSP) were studied. 2. Stroke-prone spontaneously hypertensive rats were divided into three groups: (i) the control, sedentary group; (ii) the exercise group, which was allowed to run voluntarily on running wheels; and (iii) the L-arginine intake group, which was given 2.25% L-arginine solution for 8 weeks from 4 to 12 weeks of age. In the control group, one rat died from stroke and symptoms of stroke were observed in the remaining animals. Similar symptoms were recorded in one rat of the exercise group, but not in the L-arginine group. 3. Blood pressure increased in the control group and this increase was suppressed significantly in the exercise and L-arginine groups. Thrombotic potential in cerebral vessels was the lowest at 4 weeks in all groups and was increased significantly at 12 weeks in the control group, but not in the exercise and L-arginine groups. Plasma concentrations of NO2/NO3 were lower in all animals at 12 weeks compared with those at 4 weeks. This reduction was significantly less marked in the L-arginine group. Cerebral arterioles in control rats at 12 weeks of age were significantly smaller in diameter than those at 4 weeks and these changes were less pronounced in the exercise and L-arginine groups. 4. The results provide clear evidence for the beneficial effects of L-arginine intake and voluntary exercise in mechanisms related to hypertension, thrombosis and stroke.
 ...
PMID:Effects of voluntary exercise and L-arginine on thrombogenesis and microcirculation in stroke-prone spontaneously hypertensive rats. 1022 44

Acute myocardial infarction (AMI) remains a leading cause of morbidity and mortality in the developed countries. Thrombotic occlusion of a coronary artery has been shown to cause acute myocardial infarction in over 90% of the cases. Early and complete restoration of bloodflow in the infarct-related coronary artery is the principal mechanism by which reperfusion therapy improves outcomes in patients with acute myocardial infarction. Thrombolytic therapy has been shown to reduce mortality when given early after symptom onset. However, even the most effective, approved thrombolytic regimens achieve normal (so-called TIMI 3) flow in the infarct vessel at 60-90 minutes only in about half of the patients and reocclusion occurs in 5-10%. Bleeding events, especially intracranial bleedings, observed in up to 1% of the patients, are the most severe complication of thrombolysis. Primary percutaneous transluminal coronary angioplasty (PTCA) is associated with somewhat higher patency rates and significantly fewer strokes than thrombolysis, but confers a reocclusion rate of about 5-10% and it is not universally available. While smaller randomized studies suggested a significant advantage of PTCA over thrombolysis, these results could not be confirmed in the larger GUSTO IIb angioplasty study in over 1000 patients and in non-randomized comparisons in large registries. Therefore, a general mortality advantage of PTCA over thrombolysis could not be demonstrated. Primary PTCA should be preferred in patients with contraindications against thrombolysis, patients with a high risk for intracranial bleedings (age > 75 and high blood pressure on admission) and hemodynamically unstable patients. There are several approaches to improve outcome of patients with acute myocardial infarction: new fibrinolytic agents may improve early infarct related patency, single bolus administration of thrombolytics may reduce time-to-treatment, stent implantation may improve direct PTCA, enhanced thrombin and platelet inhibition may facilitate both, thrombolysis and primary PTCA, enhance reperfusion on the cellular level and reduce reocclusions and ultimately improve prognosis of patients with acute myocardial infarction.
 ...
PMID:Thrombolysis and percutaneous transluminal coronary angioplasty in patients with acute myocardial infarction. 1081 Jul 75

Despite considerable evidence suggesting that hypertension contributes to the development and progression of atherosclerosis, the causative links remain unclear. We have tested the effects of chronic hypertension induced by suprarenal aortic constriction on the development of atherosclerosis in apolipoprotein E-deficient (Apoe-/-) mice. Compared with a sham operation, narrowing the aortic luminal diameter by 33% increased blood pressure proximal to the constriction by approximately 15 mm Hg, but the pressures distal to the constriction were unchanged. Kidney renin mRNA and plasma renin activity were also unaffected. Compared with plaque size after the sham operation, atherosclerotic plaque size in the aortic root 8 weeks after coarctation was increased to 245% and 152% in males and females, respectively. Aortic segments at the constriction were free of atherosclerotic deposits, but segments proximal to the constriction were dilated and had atherosclerotic lesions. Thrombi were present immediately below the constriction in Apoe-/- and wild-type vessels. Surprisingly, compared with wild-type mice, the Apoe-/- mice were more susceptible to the cardiac hypertrophy and dysfunction induced by pressure overload. Thus, aortic coarctation exacerbates atherosclerosis in vessels proximal to the constriction without a concomitant increase in the renin-angiotensin system. Our study also suggests that apolipoprotein E plays an important role in modulating cardiac hypertrophy.
 ...
PMID:Aortic constriction exacerbates atherosclerosis and induces cardiac dysfunction in mice lacking apolipoprotein E. 1188 92

Atrial fibrillation (AF) is the most common cardiac arrhythmia. AF is paroxysmal or persistent and becomes permanent when it does not convert to sinus rhythm spontaneously or when attempted cardioversion fails. The prevalence of AF is 0.4% in the general population and increases with age up to 6-8% in octogenarians. In men, the age-adjusted prevalence is generally higher than in women. During AF, synchronous mechanical atrial activity is disturbed, resulting in haemodynamic impairment. This can give rise to thrombus formation and embolism to the systemic circulation. Thrombus associated with AF arises most frequently in the left atrial appendage. Cerebrovascular emboli in AF patients most often manifest as transient ischaemic attacks or ischaemic strokes. The overall rate of ischaemic stroke among patients with nonrheumatic AF averages 5% per year, but the rate increases with age. Patients with AF are at higher risk of cerebrovascular events from all causes. Of all strokes, one in every six occurs in patients with AF. Including transient ischaemic attacks and silent strokes detected radiographically, the overall rate of all cerebrovascular events in AF patients rises to more than 7% per year, although approximately one third of these are due to causes that are only secondarily or incidentally associated with AF or related anticoagulant therapy. Antiarrhythmic therapy is useful to improve cardiac rate and function in AF. However, to reduce first or recurrent emboli, antithrombotic therapy is of paramount importance. Results from several randomized clinical trials of antithrombotic therapies have shown that adjusted-dose warfarin reduces first or recurrent stroke by about 60% compared with placebo. When patients with nonvalvular AF are anticoagulated, the odds against ischaemic stroke and intracranial bleeding favour an INR between 2.0 and 3.0. Acetylsalicylic acid is less efficacious than warfarin in AF patients, reducing the risk of stroke by about 20%. Therefore, this antiplatelet agent should be used only for AF patients at low risk. Anticoagulation is the current treatment modality in AF patients at high or intermediate risk, i.e. patients with history of transient ischaemic attack or stroke, those aged >65 years, those with a history of hypertension, diabetes, heart failure or structural heart disease, valvular disease or significant systolic dysfunction. The benefit of dual antiplatelet regimens in AF patients is unknown, and combining antiplatelet agents with different mechanisms of action is an important topic for future investigation.
 ...
PMID:Long-term outcome after stroke due to atrial fibrillation. 1269 12

A new experimental method of causing apparently sustained hypertension of renal origin is described. The method depends on the production of a source of micro-emboli in the thoracic aorta of rabbits by the insertion of magnesium-aluminum wire, covered by a plastic in which notches have been cut. Thrombus, considered to be formed largely of platelets, forms on the exposed areas of the wire and atrophic lesions subsequently occur along the cortical surface of the kidneys. It is probable that the atrophic lesions are due to repeated episodes of platelet micro-embolism. These lesions resemble the marginal zone of infarcts, which has been suggested as the source of a pressor substance. Proximal to the atrophic lesions, arterioles show a prominent intimal thickening resembling that seen in severe hypertension.
 ...
PMID:MICRO-EMBOLIC RENAL ISCHEMIA AND HYPERTENSION. 1424 95

The Philadelphia chromosome-negative chronic myeloproliferative disorders (CMPD), polycythemia vera (PV), essential thrombocythemia (ET) and chronic idiopathic myelofibrosis (IMF), have overlapping clinical features but exhibit different natural histories and different therapeutic requirements. Phenotypic mimicry amongst these disorders and between them and nonclonal hematopoietic disorders, lack of clonal diagnostic markers, lack of understanding of their molecular basis and paucity of controlled, prospective therapeutic trials have made the diagnosis and management of PV, ET and IMF difficult. In Section I, Dr. Jerry Spivak introduces current clinical controversies involving the CMPD, in particular the diagnostic challenges. Two new molecular assays may prove useful in the diagnosis and classification of CMPD. In 2000, the overexpression in PV granulocytes of the mRNA for the neutrophil antigen NBI/CD177, a member of the uPAR/Ly6/CD59 family of plasma membrane proteins, was documented. Overexpression of PRV-1 mRNA appeared to be specific for PV since it was not observed in secondary erythrocytosis. At this time, it appears that overexpression of granulocyte PRV-1 in the presence of an elevated red cell mass supports a diagnosis of PV; absence of PRV-1 expression, however, should not be grounds for excluding PV as a diagnostic possibility. Impaired expression of Mpl, the receptor for thrombopoietin, in platelets and megakaryocytes has been first described in PV, but it has also been observed in some patients with ET and IMF. The biologic basis appears to be either alternative splicing of Mpl mRNA or a single nucleotide polymorphism, both of which involve Mpl exon 2 and both of which lead to impaired posttranslational glycosylation and a dominant negative effect on normal Mpl expression. To date, no Mpl DNA structural abnormality or mutation has been identified in PV, ET or IMF. In Section II, Dr. Tiziano Barbui reviews the best clinical evidence for treatment strategy design in PV and ET. Current recommendations for cytoreductive therapy in PV are still largely similar to those at the end of the PVSG era. Phlebotomy to reduce the red cell mass and keep it at a safe level (hematocrit < 45%) remains the cornerstone of treatment. Venesection is an effective and safe therapy and previous concerns about potential side effects, including severe iron deficiency and an increased tendency to thrombosis or myelofibrosis, were erroneous. Many patients require no other therapy for many years. For others, however, poor compliance to phlebotomy or progressive myeloproliferation, as indicated by increasing splenomegaly or very high leukocyte or platelet counts, may call for the introduction of cytoreductive drugs. In ET, the therapeutic trade-off between reducing thrombotic events and increasing the risk of leukemia with the use of cytoreductive drugs should be approached by patient risk stratification. Thrombotic deaths seem very rare in low-risk ET subjects and there are no data indicating that fatalities can be prevented by starting cytoreductive drugs early. Therefore, withholding chemotherapy might be justifiable in young, asymptomatic ET patients with a platelet count below 1500000/mm(3) and with no additional risk factors for thrombosis. If cardiovascular risk factors together with ET are identified (smoking, obesity, hypertension, hyperlipidemia) it is wise to consider platelet-lowering agents on an individual basis. In Section III, Dr. Gianni Tognoni discusses the role of aspirin therapy in PV based on the recently completed European Collaboration on Low-dose Aspirin in Polycythemia Vera (ECLAP) Study, a multi-country, multicenter project aimed at describing the natural history of PV as well as the efficacy of low-dose aspirin. Aspirin treatment lowered the risk of cardiovascular death, non-fatal myocardial infarction, and non-fatal stroke (relative risk 0.41 [95% CI 0.15-1.15], P =.0912). Total and cardiovascular mortality were also reduced by 46% and 59%, respectively. Major bleedings were slightly increased nonsignificnsignificantly by aspirin (relative risk 1.62, 95% CI 0.27-9.71). In Section IV, Dr. Giovanni Barosi reviews our current understanding of the pathophysiology of IMF and, in particular, the contributions of anomalous megakaryocyte proliferation, neoangiogenesis and abnormal CD34(+) stem cell trafficking to disease pathogenesis. The role of newer therapies, such as low-conditioning stem cell transplantation and thalidomide, is discussed in the context of a general treatment strategy for IMF. The results of a Phase II trial of low-dose thalidomide as a single agent in 63 patients with myelofibrosis with meloid metaplasia (MMM) using a dose-escalation design and an overall low dose of the drug (The European Collaboration on MMM) will be presented. Considering only patients who completed 4 weeks of treatment, 31% had a response: this was mostly due to a beneficial effect of thalidomide on patients with transfusion dependent anemia, 39% of whom abolished transfusions, patients with moderate to severe thrombocytopenia, 28% of whom increased their platelet count by more than 50 x 10(9)/L, and patients with the largest splenomegalies, 42% of whom reduced spleen size of more than 2 cm.
 ...
PMID:Chronic myeloproliferative disorders. 1463 83

The clinical picture of cerebral venous thrombosis (CVT) depends on the site of thrombosis in the venous system including superficial veins, deep veins and venous sinuses. Thrombotic changes may occur simultaneously in various parts of the venous system. Since CVT may have various causes, the knowledge of its etiology helps to make the diagnosis. In systemic diseases multiple intravascular clots may result, while in localized pathological conditions thrombosis maybe restricted to the lesion site. The clinical picture is often serious, leading to death, or to severe complications such as pulmonary embolism, and to distant complications--like epilepsy or intracranial hypertension being the cause of chronic headaches (lumbar puncture and CSF pressure measurement are helpful in the diagnosis of intracranial hypertension). In order to prevent complications of crucial importance is not only the proper diagnosis (with MRI and venography as the diagnostic techniques of choice), but also an early and prolonged treatment with anticoagulants. Heparin or fractionated heparin is recommended even though there is a possibility of cerebral haemorrhagic lesions.
 ...
PMID:[Cerebral venous thrombosis--clinical aspects and consequences]. 1517 53

Atrial fibrillation (AF) is an independent risk factor for ischemic stroke. In patients with AF, cardioembolias present about 10% of ischemic strokes. Transesophageal echocardiography is an ideal instrument for diagnostics of intracardiac thrombi. An aim of the study was to find the high risk markers for stroke in patients with AF of non-valvular origin. The patients have been divided into 2 groups with and without stroke in anamnesis. To search for stroke dependence of clinical and echocardiographic high risk markers, the data were analyzed using Poly Analyst Power statistical package. In the group of the patients with stroke in the anamnesis, echocardiographic markers for high risk of thromboembolia occurred significantly more frequently. Thrombi in the left atrial or its appendage were registered in 12.5% patients without stroke in anamnesis and in 31% of those, who survived stroke. The independent risk factors for stroke were age, AF duration, left ventricular ejection fraction, diabetes mellitus and arterial hypertension.
 ...
PMID:[Risk and prevention of atrial fibrillation of non-valvular origin]. 1528 30

Factors that predispose to thrombus propagation from the femoropopliteal veins to the pelvic veins are poorly understood. Our goal was to determine whether there are characteristics that identify patients with massive deep vein thrombosis (DVT). We compared the 122 (2.5%) patients presenting with massive DVT (pelvic plus lower-extremity DVT) to the 4,674 (97.5%) patients with isolated lower-extremity DVT from a prospective United States multicenter DVT registry. Patients with massive DVT were younger (59.4+/-18.9 years vs. 64.3+/-16.8 years; p<0.01), less likely to have hypertension (40% vs. 51%; p=0.02), and more likely to smoke (21% vs. 13%; p=0.02) and have ongoing radiation therapy (7% vs. 3%; p=0.02). The massive DVT group more commonly presented with extremity edema (80% vs. 69%; p<0.01) and erythema (21% vs. 12%; p<0.01) than the isolated lower-extremity DVT group. However, after multivariable logistic regression analysis, extremity erythema (adjusted odds ratio 1.86; 95% CI 1.13-3.04) was the only independent sequela of massive DVT and younger age (adjusted odds ratio 1.17 per decreasing decade of age; 95% confidence interval: 1.02-1.34) was the only independent predictor of massive DVT. Thrombus propagation from the femoropopliteal system cannot be reliably predicted using demographic or clinical characteristics.
 ...
PMID:Few predictors of massive deep vein thrombosis. 1636 41


<< Previous 1 2 3 4 5 6 7 Next >>