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

The aortic content of glycosaminoglycans and collagen as well as the uptake of [125 I] albumin were studied in 53 male albino rabbits during hair-shedding and outside the period of hair-shedding to elucidate the previously reported resistance to experimental arteriosclerosis during the shedding period [1]. The concentration of hyaluronic acid was highest during hair shedding, decreasing towards the non-shedding period. The content of dermatan sulphate, chondroitin-4, 6-sulphate and hydroxyproline was lowest during sheeding and highest outside the sheeding period. Accordingly, the incorportation of [35 S] sulphate in chondroitin -4, 6-sulphate and the dermatan plus heparan sulphate fraction was increased outside shedding, consistent with a stimulated synthesis. The concentration of hyaluronic acid was negatively correlated to the uptake of [125I] albumin, and the dermatan sulphate content was positively correlated to the content of hydroxyproline. The higher concentration of hyaluronic acid during the period of shedding may improve the elastic properties as well as the ability of the aortic wall to absorbe the haemodynamic strain involved in the vascular injury of this type of experimental arteriosclerosis [2]. The decrease in the concentration of hyaluronic acid simultaneously with an increase in the aortic content of collagen as well as of chondroitin-4, 6-sulphate and dermatan sulphate may imply a greater stiffness of the aorta resulting in a higher susceptibility to injury. The relationship between hyaluronic acid and [125 I] albumin is consistent with an importance of hyaluronic acid to the susceptibility of the arterial wall to deposition of macromolecules such as the lipids. Our observations represent an example of endogenous conditioned variations in the aortic content of glycosaminoglycans and hydroxyproline accompanied by a variation in the susceptibility to experimental arteriosclerosis.
Atherosclerosis
PMID:Seasonal variations in the susceptibility of the aortic wall to atherosclerosis. Biochemical studies of glycosaminoglycans and collagen of rabbit atherosclerosis. 13 91

Electron microscopy of ruthenium red stained bovine aorta before and after chondroitinase digestion demonstrates proteoglycans on and between collagen fibrils. The collagen-associated proteoglycans include a proteoglycan previously purified from this tissue as demonstrated by immunocytochemistry and are extractable with high molar guanidine HC1. In loci rich in proteoglycans such as areas of turbulent flow in calves, more proteoglycan can be demonstrated morphologically, and these molecules also coat elastin.
Atherosclerosis
PMID:The ground substance of the arterial wall. Part 2. Electron-microscopic studies. 13 92

The changes in levels of glycosaminoglycans (GAGs) of the intima and media of the human artery in atherosclerosis were determined by a recently introduced two-dimensional electrophoresis technique that permits direct measurments of each of these macromolecules. To identify the arterial GAGs, they were fractionated by chromatography on a DEAE-Sephadex A-25 column, and the resulting three fractions (hyaluronic acid [HA], heparan sulfate [HS], and the partially separated chondroitin sulfates B [CSB] and C [CSC]) were analyzed for their electrophoretic mobilities by this electrophoretic method, for their digestability by highly specific hydrolases (leech hyaluronidase, heparinase, and chondroitinases ABC and AC) and for their iduronic acid content. From these studies we concluded that normal and atherosclerotic human aortas contain CSB, CSC, HA, and HS. Further, we demonstrated that CSB is a hybrid consisting of approximately 40% CSA and 60% CSB and that CSC appears to be a polymer consisting essentially of glucuronic acid and N-acetylgalactosamine-6-sulfate. Classical CSA as well as chondroitin (CH) were not present in detectable amounts. In the relatively normal intima, the mean concentrations of the GAGs were found to be 4.7, 20.9, 1.3, and 5.1 mg/g of dry, defatted, decalcified tissue for CSB, CSC, HA, and HS, respectively. With the progression of atherosclerosis, there was a pronounced decrease in the total GAG content (from 32 to 18 mg) associated with a decrease in the CSC and HS levels but without a change in the HA concentrations. Of particular interest, however, was the increase in the CSB level. In the media whose total GAG content averaged approximately 20 mg, no significant changes in these GAG levels were noted with the progression of the disease except for that of CSC. These findings may be important in explaining the increased lipoprotein and collagen deposition in the diseased aorta.
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PMID:The glycosaminoglycans of the human artery and their changes in atherosclerosis. 13 44

Mitral valve, coronary arteries, cartilage, and liver were studied by light and electron microscopy in a 15 year old boy with Morquio's syndrome, a genetic mucopolysaccharidosis, in which a deficiency of lysosomal hexosamine sulfatase is associated with accumulations of keratan sulfate in various organs. Coronary artery intimal sclerosis was a prominent feature of this disorder. Ultrastructural examination revealed numerous intimal smooth muscle cells containing storage vacuoles consistent with lysosomes. This was associated with marked interstitial deposition of collagen, elastin, and basement membrane material. Recent studies of human and experimental atherosclerosis have demonstrated the accumulation of cholesterol within vascular smooth muscle cell lysosomes. Intralysosomal accumulation of substrates other than cholesterol is also associated with vascular intimal sclerosis in genetic lysosomal disorders such as Fabry's disease and Hurler's syndrome. Lysosomal storage of undegraded substrate may be an important pathogenetic mechanism in the development of sclerotic vascular lesions.
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PMID:Coronary intimal sclerosis in Morquio's syndrome. 15 Jun 85

Proline hydroxylase activity and collagen content were determined in atherosclerotic plaque, fatty streak, and normal tissue from aortas of White Carneau pigeons with naturally-occurring of cholesterol-aggravated atherosclerosis. Little increase in collagen content or proline hydroxylase activity occurred in fatty streaks or plaques from birds with cholesterol-aggravated atherosclerosis. This is consistent with the morphologic observation of the presence of little or no "fibromuscular cap" in these cholesterol-aggravated lesions. Both normal and plaque tissue from arotas of birds with naturally-occurring atherosclerosis contained more collagen than did similar tissues from control birds or birds with cholesterol-aggravated lesions. The largest proportion of this increase in collagen content probably represented an age effect since it occurred in normal as well as atherosclerotic tissue. Plaques from aortas of birds with naturally-occurring atherosclerosis did contain, however, significantly more collagen than normal tissue from the same aortas. This is consistent with the presence of a prominent "fibromuscular cap" in these naturally-occurring lesions. Proline hydroxylase activity was less in these lesions than in normal tissue from the same aortas. Consequently increased proline hydroxylase activity and collagen content are not greatly altered in association with development of cholesterol-aggravated atherosclerotic lesions in pigeons. On the other hand, well-developed naturally-occurring lesions contained increased concentrations of collagen but showed no increase proline hydroxylase activity. This is not to say though, that active collagen synthesis and presukably increased proline hydroxylase activity did not take place at some point in the development of these naturally-occurring lesions.
Atherosclerosis
PMID:Proline hydroxylase activity and collagen content of pigeon aortas with naturally-occurring and cholesterol-aggravated atherosclerosis. 16 23

Present studies indicate that in explants of early atherosclerotic lesions removed from aortae of young rabbits on a 1% hypercholesterolemic diet for four and seven weeks respectively, myogenic foam cells (MCF's) were capable of emigrating into the culture medium and maintained their ability to produce microfibrils, elastic tissue elements, and collagen fibrils. In explants of the smallest lesions (fatty dots and small streaks) the MFC's divided prior to, or while emigrating. At the interphase between the primary tissue and the culture medium they contained in intracytoplasmic vacuoles fragments of elastic tissue and extraneous substances which were reminiscent of cellular debris. It is possible that this phenomenon represents a true phagocytic property of the MFC's. All formed extracellular connective tissue components were also produced by the emigrated MFC's in the tissue surrounding the cellular outgrowth. In the large fatty streaks cell division was observed at the interphase between the tissue and culture medium, but not within the substance of the explant; here cellular necrosis was prominent. The fat inclusions in the MFC's of explants and the outgrowth had the appearance of conglomerateds of unorganized, and only at times concentric, membranous profiles rather than that of homogeneous droplets observed by electron microscopy in these cells in tissue sections. In the outgrowth from explants of normal aortic areas adjacent to the lesions a moderate number of smoot muscle cells contained fat inclusions; these were almost totally absent in cells of the primary aortic cultures from normal aortae. It is conceivable that the migratory and phagocytic properties of the MFC's observed in the present study relate to some aspects of regression of atherosclerotic lesions; this, however, remains highly speculative at present.
Atherosclerosis 1977 Apr
PMID:Myogenic foam cells in explants of fatty dots and streaks from rabbit aorta. Morphological studies. 19 21

Atherosclerosis results from a precise sequence of endothelial interaction with platelets or thrombocytes and mononuclear cells, uptake of specific lipoproteins, cholesteryl ester removal, production of collagen, elastin ad proteoglycans by activated smooth muscle cells. Thus, both the filtration hypothesis and the thrombogenic hypothesis for the pathogenesis of atherosclerosis appear to be correct.
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PMID:Smooth muscle cells of intimal cushions and the localization of atherosclerotic lesions. 20 Sep 60

The amounts of buffer- and Triton-extracted apo B (LDL-protein), as well as the sum of these two fractions, were correlated with the total tissue cholesterol and hydroxyproline content (as a measure of collagen) in grossly normal intima, fatty streaks, and fibrous plaques of human aortas obtained at autopsy. Quantitative values of buffer- and Triton-extracted apo B were obtained by sequentially extracting homogenates of aortic intima with an aqueous buffer and one containing Triton X-100, and measuring the apo B content in each extract by an electroimmunoassay relative to plasma LDL or Triton-treated LDL. Significant positive correlations were obtained between the following: tissue cholesterol and both buffer-extracted and total-extracted apo B in grossly normal intima; tissue cholesterol and Triton-extracted apo B in microdissected fibrotic caps and cores of fibrous plaques, as well as in whole plaques. A positive correlation was also obtained between tissue cholesterol and total-extracted apo B in the necrotic core. A significant negative correlation was found between Triton-extracted apo B and collagen in whole plaques. The calculated mean percent of total tissue cholesterol in the different aortic regions that could be present as part of an intact LDL particle were: 100% in grossly normal intima, 16% in fatty streaks, and 11% in fibrous plaques. The positive correlation between Triton-extracted apo B and cholesterol in plaques suggests one or both of the following: the extracellular pool of cholesterol or some material increasing concurrently with cholesterol interacts with apo B or another part of the LDL particle; or the apo B containing lipoprotein is trapped in the hydrophobic environment of extracellular lipid. Both possibilities would render the particle less soluble in aqueous buffers. The negative correlation between Triton-extracted apo B and tissue collagen and the lack of a significant correlation between buffer-extracted apo B and collagen content suggests that collagen is probably not responsible for apo B retention in the aortic intima.
Atherosclerosis 1979 Mar
PMID:Correlation in the human aorta of APO B fractions with tissue cholesterol and collagen content. 22 86

Content of cholesterol and of collagen fractions (salt-, acid soluble and insoluble) in thoracal and peritoneal parts of aorta as well as concentration of products of collagen metabolism (protein-bound and free hydroxyproline) in blood plasma were studied in rabbits with various degree of atherosclerosis--separate lipid spots in aorta thoracal part (I group), total impairment of aorta (II group) and in control animals. Concentration of cholesterol and triglycerides was also studied in blood plasma and content of cholesterol, cholesterol and triglyceride esters, phospholipids and protein was measured in separate types of lipoproteins--lipoprotein of low (LPLD), of very low (LPVLD) and of high density (LPHD). Increase in content of cholesterol, salt-soluble and insoluble collagen from the both parts of aorta as well as in concentration of protein-bound and free hydroxyproline was found in rabbits of the II group as compared with the control animals. In animals of the I group content of collagen fractions in aorta was similar to that of control animals. Hypercholesterolemia, observed in both groups of rabbits, was most distinct in the II group, being related to the higher amount of cholesterol in LPLD fraction. The ratio of cholesterol esters, free cholesterol, triglycerides and phospholipids was similarly altered in LPVLD fraction of the groups of animals, mainly due to an increase in content of cholesterol esters. But rabbits of the I group were distinct from the II group of animals in the ratio of these components in LPLD: relative content of protein was lower and of cholesterol esters--higher in LPLD of the II group than of the I group. The data suggest that LPLD contained high amount of lipoproteins of intermediate density and cholesterol deposited into vessel wall from LPLD and lipoproteins of intermediate density at the increased rate. In LPHD from blood plasma of rabbits of the II group the ratios cholesterol/protein, cholesterol esters/protein as well as the molar ratio free cholesterol/phospholipids were increased; these data suggest that LPHD was saturated with cholesterol and LPHD appeared to lose the ability to eliminate cholesterol from the vessel wall. Differences in the degree of atherosclerotic impairments, existing between the I and II groups of animals, were apparently related to the variations in composition and content of lipoproteins, which regulate the level of cholesterol in vessel wall, as well as to content of collagen, i. e. they were due to features of metabolism of lipoproteins in blood plasma and of collagen in the vascular wall.
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PMID:[Plasma lipoproteins and aortic collagen fractions in rabbits with different degrees of atherosclerosis]. 22 99

Experimental atherosclerosis in rabbits induced by feeding a standard atherogenic diet for 4 months resulted in an increased sensitivity of platelets to the proaggregatory action of collagen and ADP. Treatment with dipyridamole (3 x 10 mg/day i.m.) for 4 weeks normalized platelet loss in atherosclerotic rabbits and abolished the increased sensitivity to proaggregatory collagen, but not to ADP. Dipyridamole treatment lowered basal as well as PGI2-induced cAMP levels below values seen in platelets from normal rabbits, but the stimulation by PGI2 relative to basal cAMP levels was not affected or even increased by dipyridamole treatment. Dipyridamole did not affect the increased sensitivity of platelets from atherosclerotic rabbits to the antiaggregatory action of PGI2, indicating that dipyridamole decreased absolute cAMP levels, probably due to reduction of the adenine nucleotide pool in platelets without affecting the adenylate cyclase function. Dipyridamole enhanced atherosclerotic plaque formation in arterial walls. Basal as well as PGI2-stimulated cAMP content was lower in homogenates from atherosclerotic than from normal aortic tissue. Dipyridamole-treated animals showed a further decrease in basal as well as PGI2-stimulated cAMP content of the aortic tissue, suggesting that this decrease in cAMP content may be linked to the enhanced proliferative activity seen in artherosclerotic plaque formation.
Atherosclerosis 1979 Jul
PMID:Effects of dipyridamole in experimental atherosclerosis. Action on PGI2, platelet aggregation and atherosclerotic plaque formation. 22 6


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