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

The evidence for a hemodynamic involvement and possible mechanisms by which hemodynamic-related events could influence the arterial wall, and in particular the vascular endothelium, are reviewed and used to speculate on the role of fluid mechanics in atherogenesis and specifically in lesion localization. The evidence presented suggests that it is vascular geometry, and the way it influences the local detailed flow properties, which is the primary determinant of a hemodynamic effect on the arterial wall and in the initiation of atherosclerosis.
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PMID:Atherogenesis: hemodynamics, vascular geometry, and the endothelium. 648 67

Abundant experimental evidence indicates that damage to vascular endothelium decreases intimal fibrinolytic activity, causes mural platelet and fibrin deposition, encourages proliferation of the exposed subintimal fibrocytes and smooth muscle cells, and increases endothelial permeability. These processes lead to thrombosis, subendothelial hyperplasia, or accelerated atherosclerosis. We have demonstrated in monkeys that distention of veins at high pressures (700 mm Hg), as commonly done clinically in preparation for coronary bypass, causes severe damage to the endothelium (as seen by scanning electron microscopy), and increased lipid uptake by the vein wall. The endothelium of veins distended at lower pressures (300-400 mm Hg) was not significantly different from that of undistended veins. Because of the potential late consequences of early endothelial damage to vein grafts, distention of veins before grafting to overcome spasm and to identify leaks must be done at controlled pressures. A convenient balloon device has been developed which limits the maximum pressure that can be applied when the vein is dilated.
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PMID:Prevention of endothelial damage during preparation of saphenous veins for bypass grafting. 676 34

Metabolism of arachidonic acid (AA) in blood platelets and in vascular endothelium does not lead to prostaglandins, but thromboxane A2 and prostacyclin are generated. These labile metabolites of AA antagonize each other: thromboxane A2 is a vasoconstrictor and proaggregatory agent, whereas prostacyclin dilates arteries, prevents platelets from aggregation, and dissipates the preformed platelet clumps. Prostacyclin is a powerful stimulator of adenylate cyclase in platelets and therefore its antiplatelet action is potentiated by phosphodiesterase inhibitors such as theophylline or dipyridamole. Cyclo-oxygenase of AA is inhibited by aspirin, thromboxane synthetase by analogues of prostaglandin endoperoxides, and prostacyclin synthetase by linear lipid peroxides. A hypothesis is put forward that atherosclerosis develops because of pathological, nonenzymic lipid peroxides. A hypothesis is put forward that atherosclerosis develops because of pathological, nonenzymic lipid peroxydation in the body and the subsequent molecular damage to prostacyclin synthetase in the rheologically determined areas of arterial walls. Endothelium deprived of prostacyclin is the basis for microthrombi formation, and follows a sequence of events described by Rokitansky and later by Ross. Prostacyclin is also a circulating hormone which is generated by the lungs. Thereby a damage of this "endocrine gland" by respiratory disorders, air pollution, or tobacco smoking are likely to contribute to pathogenesis of atherosclerosis, myocardial infarction, and arterial thromboembolism. Pharmacological treatment and prevention of these diseases should logically include antioxydants, prostacyclin and its analogues, thromboxane synthetase inhibitors and perhaps cyclooxygenase inhibitors (aspirin ?). Prostacyclin was already infused intravenously to men and its powerful antiaggregatory and deaggregatory actions were demonstrated. These properties of prostacyclin along with its vasodilator and positive inotropic actions destine this hormone to be a new type of antithrombotic drug in acute myocardial infarction.
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PMID:Prostaglandins, platelets, and atherosclerosis. 677 Nov 2

This article reviews the experimental and clinical evidence regarding heparin therapy in the prophylaxis of coronary heart disease. The actions of heparin take place at the vascular endothelium where injected heparin concentrates, and within the bloodstream. At the endothelium heparin acts to prevent endothelial injury, prevent thrombin generation, prevent platelet adhesion to endothelium, and to decrease uptake of serum lipoproteins. Within the bloodstream heparin increases lipoprotein lipase activity and reduces the concentration of atherogenic very low-density lipoproteins. The reduction in lipemia enhances oxygen transfer from blood to the tissues, and decreases thrombin or ADP-induced platelet aggregation. Heparin increases the concentration of high-density lipoproteins. It decreases hypercoagulability and inhibits overactivation of serum complement. Heparin reduced atherosclerosis in most studies in cholesterol-fed animals. In human subjects who had a myocardial infarct at least one year before the onset of treatment, long-term intermittent heparin therapy significantly decreased cardiovascular deaths as compared to control groups.
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PMID:Heparin and atherosclerosis. A review of old and recent findings. 698 41

Cultured mouse peritoneal macrophages secrete a growth-promoting activity that stimulates 3 types of nonlymphoid mesenchymal cells in vitro: fibroblasts, vascular smooth muscle, and vascular endothelium. Production of this macrophage-derived growth factor (MDGF) is directly related to the number of viable macrophages and their time in culture, and is independent of platelet- or plasma-derived serum growth factors. Treatment of cultured macrophages with latex, bacterial lipopolysaccharide, or phorbol myristate acetate results in increased growth factor activity. Preliminary biochemical characterization of MDGF indicates that it is a heat labile (100 degrees C, 2 min), non-dialyzable protein, which contains at least 1 essential disulfide bond. Growth-promoting activity is not adsorbed by CM-Sephadex chromatography, under conditions that effectively remove platelet-derived growth factor(s). Serine protease activity is not required for the action of MDGF. Secretion of macrophage-derived growth factor may be relevant to the function of mononuclear phagocytes in several pathologic processes, including the neovascularization and fibroplasia of wound healing, smooth muscle hyperplasia in atherosclerosis, and proliferative glomerulonephritis.
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PMID:Stimulation of nonlymphoid mesenchymal cell proliferation by a macrophage-derived growth factor. 720 74

Human endothelial cells in culture is shown to synthesize antithrombin III (At-III). The endothelial cell At-III (EC-At-III) consists of a small fraction similar to plasma At-III and a larger fraction with decreased heparin-binding as tested by crossed immunoelectrophoresis. However, both the anti-Xa and thrombin-neutralizing activities of the EC-At-III were rapid and active even in the absence of added heparin. It is concluded that the major portion was probably bound to endogenous heparin-like substance, thus accounting for its decreased exogenous heparin binding. The presence of At-III and other antithrombotic factors in the vascular endothelium offer protection against thrombosis and possibly atherosclerosis.
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PMID:Antithrombin III, the major modulator of intravascular coagulation, is synthesized by human endothelial cells. 730 89

Experimental Marek's disease virus (MDV) infection in chickens was used to study the early pathogenesis of virus-induced atherosclerosis. Previous investigations using this model have reported the occurrence of atherosclerotic lesions after approximately 7 months postinfection. In this study, a total of 75 susceptible Cornell P-line chickens were inoculated intraperitoneally with the CU-2 strain of MDV at 3 days of age and subsequently perfused for histologic examination. At 2, 4, 8, 13, and 20 weeks postinoculation, the ascending aorta and the brachiocephalic and coronary arteries were evaluated for early changes. Expression of class II major histocompatibility complex (Ia) antigen by the vascular endothelium was demonstrated by indirect immunodetection as early as 2 weeks after virus inoculation. This change was followed by significant thickening of the intimal layer associated with mononuclear cell infiltration. All the arteries examined from the MDV-infected chickens were affected. Preliminary immunohistochemical staining showed the presence of CD3+ CD4+, and CD8+ cells among the infiltrating cells. The results suggest that an immunopathologic mechanism may be involved in the early pathogenesis of MDV-induced atherosclerosis in chickens.
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PMID:Endothelial MHC class II antigen expression and endarteritis associated with Marek's disease virus infection in chickens. 748 15

There is evidence that vascular endothelium directs the accumulation of leukocytes in inflammation through various means, particularly by the expression of specific cell surface molecules which are adhesive for ligands on circulating leukocytes. Examples of such molecules are E-selectin and intercellular adhesion molecule 1 (ICAM-1). In an experimental model of various forms of inflammation, E-selectin and ICAM-I were induced in association with adhesion and emigration of circulating polymorphonuclear and mononuclear leukocytes. Further work in humans showed endothelium to express E-selectin in inflammation. In addition, the presence of a leukocyte ligand for E-selectin, sialyl-Lewis X, has been seen on cells accumulating in inflammation. Furthermore, sialyl-Lewis X was also unexpectedly seen on endothelium. The role of sialyl-Lewis X on endothelium is as yet uncertain, although it may function as an adhesion receptor for leukocytes. Other endothelial adhesion receptors, such as vascular cell adhesion molecule 1 (VCAM-1), are described. Atherosclerosis shows many features in common with inflammation. These are discussed, and the demonstrated and potential relevance of endothelial adhesive phenomena in routine inflammation to those in atherosclerosis are reviewed. For example, a VCAM-1 homologue has been described on the endothelium over evolving atherosclerotic lesions in rabbits.
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PMID:Endothelial-leukocyte adhesive interactions in inflammatory diseases. 751 Jun 38

Hemodynamic forces induce various functional changes in vascular endothelium, many of which reflect alterations in gene expression. We have recently identified a cis-acting transcriptional regulatory element, the shear stress response element (SSRE), present in the promoters of several genes, that may represent a common pathway by which biomechanical forces influence gene expression. In this study, we have examined the effect of shear stress on endothelial expression of three adhesion molecules: intercellular adhesion molecule-1 (ICAM-1), which contains the SSRE in its promoter, and E-selectin (ELAM-1) and vascular cell adhesion molecule-1 (VCAM-1), both of which lack the SSRE. Cultured human umbilical vein endothelial cells, subjected to a physiologically relevant range of laminar shear stresses (2.5-46 dyn/cm2) in a cone and plate apparatus for up to 48 h, showed time-dependent but force-independent increases in surface immunoreactive ICAM-1. Upregulated ICAM-1 expression was correlated with increased adhesion of the JY lymphocytic cell line. Northern blot analysis revealed increased ICAM-1 transcript as early as 2 h after the onset of shear stress. In contrast, E-selectin and vascular cell adhesion molecule-1 transcript and cell-surface protein were not upregulated at any time point examined. This selective regulation of adhesion molecule expression in vascular endothelium suggests that biomechanical forces, in addition to humoral stimuli, may contribute to differential endothelial gene expression and thus represent pathophysiologically relevant stimuli in inflammation and atherosclerosis.
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PMID:Shear stress selectively upregulates intercellular adhesion molecule-1 expression in cultured human vascular endothelial cells. 751 44

The rate of atherosclerosis is accelerated in humans with diabetes. The adhesion of monocytes to the vascular endothelium is a key event in the development of atherosclerosis. Alloxan (ALX)-induced diabetes in rabbits causes leukocyte accumulation on the arterial surface. However, the effect of glucose exposure on monocyte binding is not understood. We evaluated the effect of chronic elevated glucose on human monocyte binding to human aortic endothelial cells (HAEC) in culture. Monocyte binding to HAEC was significantly increased by chronic incubation of HAEC in high glucose for 7-10 days (CH-HG; 25 mM) compared with cells cultured for the same time in normal glucose (5.5 mM; CH-HG, 188 +/- 10 cells/field vs. normal glucose, 111 +/- 7; P < 0.0005). Use of mannitol at a concentration to stimulate the hyperosmolar effects of glucose did not significantly alter monocyte binding. Acute 20-min exposure of HAEC to high glucose did not alter monocyte binding. The adherence of HL-60 cells, a neutrophil-like cell line, or human neutrophils was not induced by CH-HG culture. High glucose-induced monocyte binding was not associated with induction of the major endothelial cell adhesion molecules, including E-selectin, vascular cell adhesion molecule 1, and intercellular adhesion molecule 1 (ICAM-1). A monoclonal antibody TS1-18 to the beta 2 integrin component that is involved in binding to ICAM-1 on endothelial cells significantly reduced monocyte binding, whereas anti-VLA-4 antibody was not effective. These results suggest that hyperglycemia can accelerate the rate of atherosclerosis in diabetics by increasing monocyte binding to the endothelium.
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PMID:Evidence that glucose increases monocyte binding to human aortic endothelial cells. 752 Aug 76


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