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

Endothelial cells from porcine aorta and inferior vena cava have been harvested, using trypsin, EDTA or collagenase, and grown in tissue culture. Growth-behaviour, cytology, scanning and electronmicroscopy findings are reported. It is hoped that this technique will prove useful in the investigation of atherosclerosis.
Atherosclerosis
PMID:The porcine endothelial cell in tissue culture. 16 26

A large amount of plasma low density lipoprotein is present in human aortic intima, and this can be removed and measured by electrophoresis directly from the minced tissue into an antibody-containing gel. We now find that, in addition to this electrophoretically mobile lipoprotein, there is an immobilized lipoprotein fraction than can be released from lesions by incubation of the tissue sample with plasmin or other proteolytic enzymes after the mobile lipoprotein has been removed. The concentration of immobilized lipoprotein is highly correlated with the concentration of the residual cholesterol (not mobile on electrophoresis) that has accumulated in the tissue (r = 0.702; P less than 0.001). Thus, in normal intima and early gelatinous lesions it is about 15% of the concentration of mobile lipoprotein, whereas in the atheroma lipid layers of fibrous or gelatinous plaques it may be 2 or 3 times greater than the concentration of mobile lipoprotein. This suggests that immobilization of plasma lipoprotein is an intermediate step in the irreversible deposition of extracellular cholesterol in atherosclerotic lesions. Incubation with plasmin allowed maximum release of lipoprotein: plasmin = crude collagenase greater than trypsin greater than "pure" collagenase greater than chondroitinase ABC in order of their relative effectiveness. The concentration of immobilized lipoprotein was significantly correlated (r = 0.793; P less than 0.001) with the concentration in the tissue of fibrin or other insoluble derivatives of fibrinogen ("fibrin"). In aliquots of lesions incubated with varying amounts of plasmin for varying times there was a constant relation between release of lipoprotein and release of fibrin-degradation products. Together, these findings suggest that the lipoprotein is associated with insoluble "fibrin". This appears to be of considerable clinical interest, suggesting a synergism between lipoprotein and fibrinogen in the accumulation of lipid in lesions.
Atherosclerosis 1976 Oct
PMID:The release of an immobilized lipoprotein fraction from atherosclerotic lesions by incubation with plasmin. 18 79

High density lipoprotein (HDL) inhibited the binding (trypsin-releasable radioactivity), internalization (cell-associated radioactivity after trypsinization), and degradation (TCA-soluble non-iodide radioactivity) of (125)I-low density lipoprotein ((125)I-LDL) by cultured normal human fibroblasts. At HDL:LDL molar ratios of 25:1 (protein ratios about 5:1), these parameters were reduced by about 25%. Unlabeled LDL was about 25 times more effective in reducing (125)I-LDL binding, implying that if HDL and LDL bind at common sites the affinity of HDL for these sites is very low or that the interaction is on some other basis. The fractional reduction in (125)I-LDL binding at a given HDL: (125)I-LDL ratio was independent of (125)I-LDL concentration and occurred equally with fibroblasts from a subject with homozygous familial hypercholesterolemia. Reciprocally, the binding, internalization, and degradation of (125)I-HDL were reduced by LDL. Preincubation of fibroblasts with HDL (or LDL) reduced the subsequent binding of (125)I-LDL (or (125)I-HDL) during a second incubation. In other studies HDL reduced the net increase in cell cholesterol content induced by incubation with LDL. HDL alone had no net effect on cell cholesterol content. These findings suggest that HDL reduces both the high affinity and the low affinity binding of LDL to human fibroblasts and that this in turn reduces the internalization and degradation of LDL. The effect of HDL on the LDL-induced changes in cell cholesterol content could be in part on this basis and in part on the basis of an HDL-stimulated release of cholesterol from the cells. These effects of HDL in vitro may be relevant to the negative correlations reported from in vivo studies between plasma HDL concentration and both body cholesterol pool size and the prevalence of clinically manifest atherosclerosis but further studies will be needed to establish this.
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PMID:Interaction between high density and low density lipoproteins uptake and degradation by cultured human fibroblasts. 19 23

An isotopic assay of elastolytic activity is performed; the iodine-125 ions retained inside the elastin framework were removed by appropriate treatment. This acute substrate enables us to study the role of trypsin on elastase activity and facilitates the study of elastase role in atherosclerosis.
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PMID:[Improvements in the technical conditions for the evaluation of an elastolytic activity. The role of tryspin as an activator (author's transl)]. 23 67

Hypercholesterolemia was induced in rats by feeding them a high cholesterol olive oil diet. The livers were homogenized in modified Krebs-Ringer medium and centrifuged at 35,000 x g. The supernatants from livers of both hypercholesterolemic and normal rats were found to stimulate collagen synthesis in freshly isolated embryonic chick-tendon fibroblasts. However, this was significantly greater in the supernatants from fatty livers. The stimulating principle proceed to be dialyzable, non-lipid and heat-stable. There were at least two factors involved, the more effective of which was trypsin-sensitive, with a molecular weight below 2,000. The results suggest that a mediator is formed in the livers of hypercholesterolemic rats which might be responsible for the enhanced collagen synthesis of fibrotic processes vivo, e.g., in atherosclerosis and liver cirrhosis.
Atherosclerosis
PMID:Factors stimulating collagen synthesis from the livers of hypercholesterolemic rats. 94 25

Endothelial cells from human umbilical cords were harvested, using a trypsin technique, grown in tissue culture and lipid synthesis studied using [1-14C]acetate as a precursor. Radiosubstrate was incorporated into fatty acids, mono-, di- and triglycerides, cholesterol esters and phospholipids. Radioactivity was also present in the culture medium in the mono-and diglyceride fractions and in the phospholipids running with the solvent front.
Atherosclerosis
PMID:The synthesis of lipids from [1-14C]acetate by human venous endothelium in tissue culture. 100 11

Cells from aortas of newborn and adult rabbits were liberated by digestion with trypsin and collagenase. More than 90% of them were viable at the end isolation. Isolated cells were used for electron microscopic examination. In the material obtained from aortas of newborn rabbits endothelial cells, fibroblasts and smooth muscle cells were present. In material from adult rabbits two kinds of endothelial cells, fibroblasts, several varieties of myocytes, fat-laden macrophages and typical foam cells were found. Various forms of myocytes seem to represent different functional stages or specialized kinds of these cells. The presence of fat laden macrophages and foam cells in the aortas of healthy adult rabbits may support the view that these cellular changes so far considered as typical of atherosclerosis are common and may be treated as an exponent of natural process of aging of vascular wall.
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PMID:Electron microscopic studies on cells isolated from aorta of newborn and adult rabbits. 122 11

Cells from aortas of healthy newborn and adult rabbits were liberated by digestion with trypsin and collagenase. In the same way were obtained free cells from the aortas of rabbits with far advanced experimental atherosclerosis. More than 90 p. 100 of the cells from all groups were viable. Isolated cells were used for electron microscopic examination. In material obtained from aortas of newborn rabbits, endothelial cells, fibroblasts and smooths muscle cells were present. In adult rabbits two kinds of endothelial cells, fibroblasts, several varieties of myocytes and foam cells were found. The bulk of aortic cells isolated from rabbits with experimental atherosclerosis consisted of endothelial cells and smooth myocytes. The cytoplasm of all myocytes contained lipid vacuoles. The lipid-loaded myocytes corresponded to the typical foam cells. Lipid content was relatively scanty in the endothelial cells. The presence of myocytes foam cells like in the aortas of healthy adult rabbits, identical as in material from experimental atherosclerosis, may support the view that these cellular changes so far considered as typical for atherosclerosis are common, and may be treated as an exponent of the natural process of aging of the vascular wall.
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PMID:Comparison of morphology of isolated cells obtained from aortas of normal and cholesterol fed rabbits. 123 42

Plasmin inhibition by alpha 2-antiplasmin (alpha 2AP) is regulated by the vascular components fibrin(ogen) fragments, plasminogen and lipoprotein (a). Kinetic analysis demonstrates that CNBr-derived fibrinogen fragments completely protect plasmin from alpha 2AP. Plasminogen and 6-aminohexanoic acid decrease the rate of inhibition by 5- and 10-fold respectively. These studies show that CNBr-derived fibrinogen fragments and 6-aminohexanoic acid bind plasmin kringle(s) with binding constants of 2 micrograms/ml and 120 microM respectively, and that plasminogen binds to alpha 2AP with an affinity of 0.5 nM. The unmodulated inhibition is not effected by the presence of lipoprotein (a), but in the presence of protective CNBr-derived fibrinogen fragments the rate of inhibition is increased by the presence of the lipoprotein. The kinetics demonstrate that lipoprotein (a) binds to CNBr-derived fibrinogen fragments with an affinity of 4 nM, displacing plasmin from the protective surface. In addition, tissue-type plasminogen activator and trypsin inhibition by alpha 2AP is not slowed by the presence of CNBr-derived fibrinogen fragments or plasminogen (Pg), respectively. These kinetics suggest that the initial reversible interaction between plasmin and alpha 2AP is mediated by binding of the inhibitor to the kringle 1 domain of plasmin, with a reversible inhibition constant (Ki) of 5.0 x 10(-10) M. Under conditions where this kringle-inhibitor interaction is blocked, the reversible inhibition still occurs between the plasmin and alpha 2AP, but the initial Ki is increased to 5.0 x 10(-9) M. These data suggest that, in the circulation, plasmin inhibition by alpha 2AP may be down-regulated by fibrin, fibrin(ogen) fragments and Pg, but up-regulated by lipoprotein (a) in the presence of fibrin or fibrin(ogen) fragments. The lipoprotein (a)-mediated promotion of plasmin inhibition may provide an additional mechanism by which the lipoprotein impairs fibrinolysis and promotes atherosclerosis.
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PMID:Lipoprotein (a) promotes plasmin inhibition by alpha 2-antiplasmin. 138 85

Both macrophages and platelets play an important role in atherogenesis. We studied the effect of conditioned medium obtained from human monocyte-derived macrophages on in vitro platelet aggregation. Incubation of macrophage-conditioned medium (MCM) with platelets resulted in enhanced platelet aggregation (up to 35% difference between basal and MCM-stimulated activity), which was time dependent. This MCM effect on platelet function was increased both with time of mononuclear cell culturing (up to 10 days) and with the time of macrophage incubation in serum-free medium (up to 24 hours) prior to MCM collection. MCM from either cholesterol-loaded macrophages or from macrophages obtained from patients with familial hypercholesterolemia demonstrated a 37% and 20% increased effect, respectively, in comparison to MCM derived from normal subjects. Macrophage activation with lipopolysaccharide resulted in the harvesting of a MCM that enhanced platelet activity 60% more than MCM obtained from nonactivated cells. The active component of MCM was inhibited fivefold following heating at 100 degrees C for 10 minutes or after treatment with trypsin or protease, but was not affected by antioxidants. MCM activation of blood platelets may be of importance in atherogenesis. Understanding the mechanisms involved may contribute to an improved appreciation of the role of both platelets and macrophages in atherosclerosis.
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PMID:Secretory products from human monocyte-derived macrophages enhance platelet aggregation. 200 39


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