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

Arterial hypertension is considered a major risk factor in atherosclerosis in the pathogenesis of which platelet activity plays a fundamental role. However the data in the literature on platelet function in arterial hypertension do not always agree. The present study was conducted on whole blood, using the impedance metering technique to assess platelet aggregation induced by ADP (10 pg) and collagen (2 mg/ml) in 15 patients with uncomplicated essential hypertension and 25 healthy controls. Analysis of the data shows a statistically significant difference between the aggregation curves of the hypertensive and the healthy subjects with excessive platelet aggregation in those suffering from uncomplicated arterial hypertension.
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PMID:[Platelet aggregation in whole blood with the impedance method in subjects with non-complicated essential arterial hypertension]. 296 26

We demonstrate that zinc (0.1 to 0.3 mmol/L) induces aggregation of washed platelet suspensions. Higher concentrations (1 to 3 mmol/L) of zinc were needed to aggregate platelets in platelet-rich plasma obtained from blood anticoagulated with low-molecular-weight heparin, probably due to the binding of zinc to the plasma proteins. Zinc-induced aggregation of normal washed platelets required added fibrinogen and no aggregation occurred with thrombasthenic platelets or with normal platelets pretreated with a monoclonal antibody (10E5) that blocks the platelet fibrinogen receptor. These data indicate that the platelet membrane fibrinogen receptor-glycoproteins IIb and IIIa mediate the effect of zinc. Zinc-induced aggregation was blocked by the agent TMB-8, which interferes with the internal calcium flux, and by prostacyclin, which elevates platelet cyclic adenosine monophosphate levels. Zinc-induced aggregation was not accompanied by thromboxane synthesis or by the secretion of dense-body serotonin and was not affected by preexposure of platelets to acetylsalicylic acid. Experiments with creatine phosphate/creatine phosphokinase showed that the zinc effect on platelets was independent of extracellular adenosine diphosphate (ADP). Zinc had an additive effect when platelet aggregation was stimulated with subthreshhold concentrations of collagen or ADP. Together with the known effects of nutritional zinc on in vivo bleeding, on platelet aggregation, and on lipid metabolism, the results suggest that zinc may have an important bearing on normal hemostasis, thrombosis, and atherosclerosis.
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PMID:Zinc-induced platelet aggregation is mediated by the fibrinogen receptor and is not accompanied by release or by thromboxane synthesis. 298 68

For a historical survey of the pathogenesis of atherosclerosis the reader is referred to references 1 and 2. Comprehension of the vessel-blood interface homeostasis hinges upon an understanding of the pathophysiology of angio-lymphoid relationships. Even in the smooth contact of the intact hydrophobic intimal lining with the marginal flow of the circulatory stream, small amounts of thrombin and small aggregates of aging platelets float by under physiologic conditions. Since endothelial cells of the vascular intima contain receptors for thrombin, filling these receptors with thrombin becomes a stimulus for the production of prostacyclin (PGI2) by the endothelial cells; PGI2 in turn inhibits adherence of the small platelet aggregates by ADP; homeostasis is maintained. The size of physiologic thrombin-producing platelet microaggregates is controlled by physiologic levels of antithrombin III.
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PMID:Atherosclerosis. I. A leiomyoproliferative disease of the arteries resulting from breakdown of the endothelial barrier to potent blood growth factors. II. Perspectives in atheroprophylaxis. 299 35

Functional and biochemical alterations of platelets in patients suffering from atherosclerosis were studied in our laboratory. One of the most striking alterations observed is in the platelet active glucose transport system. The Na+/K+ gradient dependent active transport system of glucose is found to be absent in the platelets of atherosclerotics. The platelet glucose transport kinetics in these subjects give unsaturable and linear kinetics. Furthermore, the specific glucose binding protein activity detected in the incubation fluid after cold osmotic shock to the platelets of normal subjects is found to be absent in the platelets of atherosclerotics. The platelet active glucose transport system is normal in juvenile onset diabetics, whereas it is impaired in maturity onset diabetics with clinical manifest atherosclerosis. The release inducers like ADP, adrenalin and collagen exert no effect on the platelet active glucose transport system. The specific glucose-binding protein is an unreleasable protein in the platelets of normal subjects. Hence, the absence of active glucose transport system in atherosclerotics is not due to the activated platelets in circulation.
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PMID:Alteration of platelet glucose transport system in atherosclerosis. 301 May 81

Dual control of local blood flow by purines is described: adenosine 5'-triphosphate (ATP) released as a cotransmitter with noradrenaline from perivascular sympathetic nerves acts on P2X-purinoceptors on smooth muscle cells to produce vasoconstriction; ATP released from endothelial cells during hypoxia (and ADP released from aggregating platelets) acts on P2Y-purinoceptors on endothelial cells which results in production of endothelium-derived relaxing factor and subsequent vasodilatation. It is suggested that the endothelial-mediated vasodilatation is a pathophysiological mechanism to protect the host tissue (e.g. brain or heart) from damage produced by hypoxia following ischaemia. The ATP released from the endothelial cells is rapidly broken down to adenosine which augments this protective mechanism by acting directly on P1-purinoceptors on vascular smooth muscle to produce a longer lasting component of vasodilatation and on perivascular sympathetic nerve terminals to inhibit release of excitatory neurotransmitters. The possibility that impairment of normal endothelial-mediated responses in atherosclerosis and hypertension can lead to local vasospasm is considered.
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PMID:Local control of blood pressure by purines. 303 84

The aim of the study was to investigate the influence of calcium blockers on the prostaglandin system of blood platelets and the vessel wall with respect to a possible beneficial effect on atherosclerosis. The influence of diltiazem, isradipine, nifedipine and verapamil was examined on ADP- and collagen-induced in vitro platelet aggregation, platelet malondialdehyde formation and other platelet function tests. All the calcium blockers investigated inhibited platelet activation in a dose-dependent manner, isradipine being the most effective. Malondialdehyde formation (measured photometrically) and thromboxane (TX) B2 production were decreased too. Vascular tissue PG12 formation was investigated in rat aortic rings (6-oxo-PGF1 alpha-RIA). PG12 formation was enhanced by all the calcium blockers investigated (p less than 0.01), isradipine again having the most pronounced effect. Platelet adenylate cyclase was stimulated by diltiazem only (RIA, HPLC). Ex vivo ADP-, collagen- and epinephrine-induced platelet aggregation and serum TX were studied 90 minutes after ingestion to diltiazem (60 mg), nifedipine (20 mg) and verapamil (40 mg). ADP- and epinephrine-induced platelet aggregation (19-36%) and serum TX were reduced significantly (p less than 0.01), but collagen-induced aggregation was not significantly affected. These results suggest a possibly beneficial effect of calcium blockers on atherosclerosis via the prostaglandin system.
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PMID:[Calcium antagonists: anti-atherosclerotic effect by modification of the prostaglandin system]. 307 22

The Ivanovas-Sieve (IVA-SIV) rat represents the only available animal model of endogenous hypertriglyceridemia, in the absence of obesity and/or overt diabetes. Since plasma lipids/lipoproteins can modulate platelet reactivity and eicosanoid metabolism, these were examined in two groups of Charles River (CR) and IVA-SIV rats of identical age. The IVA-SIV rats had 2-fold higher plasma triglycerides and a 55% higher number of circulating platelets; the number of platelets was significantly correlated with triglyceridemia. Platelet reactivity to ADP and to collagen was significantly reduced in these animals, whereas the formation of thromboxane B2 did not differ from that of the CR. After perfusion of platelet-rich plasma (PRP) through the aortas of animals of the two strains, platelet aggregability, already lower in the IVA-SIV, was reduced to a higher extent compared to the CR. Increased levels of the prostacyclin metabolite 6-keto-PGF1 alpha were identified in the perfusate from the aortas of IVA-SIV rats. Platelets from these animals also showed an increased sensitivity to Iloprost, a stable prostacyclin analogue, with an IC50 1.7-fold lower compared to CR rats. Spontaneous hypertriglyceridemia in the IVA-SIV model is not associated with platelet hyperresponsiveness, but rather with a reduced sensitivity to major aggregants.
Atherosclerosis 1988 Nov
PMID:Reduced platelet aggregability and increased vascular prostacyclin formation in a variant rat strain (IVA-SIV) with endogenous hypertriglyceridemia. 321 76

The effects of intake of dried garlic on blood coagulation, fibrinolysis, platelet aggregation, serum cholesterol levels, and blood pressure were studied in 20 patients with hyperlipoproteinemia over a period of four weeks. Fibrinogen and fibrinopeptide A significantly decreased by 10%. Streptokinase activated plasminogen and fibrinopeptide B beta 15-42 significantly increased by about 10%. Serum cholesterol levels significantly decreased by 10%. Systolic and diastolic blood pressure decreased. ADP and collagen induced platelet aggregation were not influenced.
Atherosclerosis 1988 Dec
PMID:Effect of dried garlic on blood coagulation, fibrinolysis, platelet aggregation and serum cholesterol levels in patients with hyperlipoproteinemia. 324 Mar 34

In a cross-sectional population study of 1132 unselected Eastern Finnish men aged 54 years, serum selenium concentration had a weak positive association with plasma HDL cholesterol (standardised partial regression coefficient, beta = 0.061, P = 0.019) and a fairly strong inverse relationship (beta = -0.223, P less than 0.001) with the extent of ADP-induced platelet aggregation. Neither plasma ascorbate concentration nor alpha-tocopherol to total cholesterol ratio had any association with plasma lipoproteins, platelet aggregability or prevalent ischaemic heart disease (IHD). When a covariance-correction was applied, men with ischaemic ECG findings at exercise had a lower mean serum selenium than others (81.5 micrograms/l vs. 85.9 micrograms/l, P less than 0.01 for difference). This difference was equally large for men with neither symptoms nor previous diagnosis of IHD.
Atherosclerosis 1988 Mar
PMID:Relationship of serum selenium and antioxidants to plasma lipoproteins, platelet aggregability and prevalent ischaemic heart disease in Eastern Finnish men. 325 19

Shear stress activated platelets undergo aggregation in the presence of large or unusually large von Willebrand factor (vWF) multimers without the addition of ristocetin or any other exogenous chemical. This phenomenon may be analogous to the platelet aggregation that leads to thrombosis in the narrowed arteries and arterioles of patients with atherosclerosis or vasospasm. A triphenyl-methyl compound, aurin tricarboxylic acid (ATA), inhibits shear-induced, vWF-mediated platelet aggregation in platelet-rich plasma (PRP) in concentrations above 200 mumol/L and in buffer suspensions of washed platelets at a concentration of 0.1 mumol/L. In a concentration-dependent manner, ATA also inhibits ristocetin-induced, vWF-mediated platelet clumping in both fresh and formaldehyde-fixed platelet suspensions. This inhibition can be overcome by increasing the concentration of vWF, following the kinetics of first order competitive inhibition. ATA prevents the attachment to platelets of the largest vWF multimeric forms found in normal plasma and of the unusually large vWF multimers derived from endothelial cells. The rate of aggregation and degree of inhibition by ATA is not accounted for by the binding of ristocetin or calcium. Arachidonic acid- and adenosine diphosphate (ADP)-induced aggregation are not inhibited by ATA. Platelets incubated with ATA can be easily separated from the compound. However, ATA binds to large vWF multimeric forms and inhibits their ristocetin-induced interaction with platelet glycoprotein Ib. Because ATA also inhibits shear-induced, vWF-mediated platelet aggregation in vitro in the absence of ristocetin, it may be a useful prototype compound to impede the development of arterial thrombosis in vivo.
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PMID:Aurin tricarboxylic acid: a novel inhibitor of the association of von Willebrand factor and platelets. 326 93


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