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

The effect of permanent occlusion on the carotid artery of the rat was studied by light and by electron microscopy. A segment between two ligatures was examined at times from 2 minutes to 1 year. Between 2 and 15 minutes after occlusion, the red blood cells adjacent to the wall formed radially arranged rouleaux; within 24 hours the endothelium disappeared, while platelets (despite the lack of flow) accumulated against the denuded elastica. This behavior of formed blood elements may have been the result of electric forces (injury potential). By 3 days, undifferentiated cells were found lining the elastica interna or free in the lumen; they apparently were derived from medial smooth muscle.In the media, by 3 days some smooth muscle cells had become necrotic, while "undifferentiated" cells appeared; strong circumstantial evidence suggested that these were smooth muscle cells which had lost their specific characteristics and had thus become dedifferentiated (a phenomenon also known to occur in striated muscle cells); by 1 month they had matured into smooth muscle, but the media from then on contained fewer cells and more collagen than normal.In the lumen, the undifferentiated cells also matured into typical smooth muscle cells from 15 days onward, while collagen and elastin appeared between them. After 1 month these cells began to accumulate droplets of fat, which thereafter increased in number (at 6 months they were associated with cholesterol clefts) and then declined. This accumulation of fat in smooth muscle cells (also seen in atherosclerosis) was interesting because it occurred in the absence of blood flow.
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PMID:Effect of occlusion on large vessels. I. A study of the rat carotid artery. 87 75

Collagen, elastin and non-fibrous protein synthesis were measured in the aortas of male New Zealand white rabbits fed a diet containing 2% cholesterol for 140 or 180 days. At these time periods increases in aortic cholesterol and cholesteryl esters were evident. The atherosclerotic lesions induced were predominantly of the foam cell type although some areas of early fibrous lesion formation were noted. These changes in lipid concentration and arterial morphology were accompanied by a significant increase in collagen synthesis as determined by the formation of [14C]hydroxyproline. This increase, however, was not confined specifically to collagen since both elastin and non-collagenous proteins were also being synthesized at a higher rate. The two-fold increase in the rates of both fibrous and non-fibrous protein synthesis may in part be a consequence of marked intimal hyperplasia necessitating a general increase in protein synthesis.
Atherosclerosis 1977 Aug
PMID:Stimulation of aortic protein synthesis in experimental rabbit atherosclerosis. 88 2

The authors examined collagenous neosynthesis in the aortic wall of rats with experimental atherosclerosis after application of 3H-proline, a precursor of collagen, as well as subsequent determination of the radioactivity in the aortic wall by means of scintiliation counting and localization of the incorporated radioisotope by radioautography (optical and electron microscopic). There was a great increase of the incorporation of 3H-proline in the atherosclerotic aortas in comparison with controls, a manifestation of raised neosynthesis of collagen in the cellular elements of the aortic wall in atherosclerosis. The elevated collagenogenosis was due mainly to an increased synthetic activity of the modified smooth muscle cells, forming fibrous atherosclerotic plaques. This was proven by their more intensive radioisotopic marking in comparison with medial smooth muscle cells in the optical and electrone microscopic radioautograms.
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PMID:[Collagen biosynthesis in the arterial wall in experimental atherosclerosis]. 89 50

Controversy exists as to whether regression occurs in atherosclerotic plaques in response to serum cholesterol reduction. In the present study, using sequential observation of canine atherosclerosis, we attempted regression in hypothyroid dogs. Animals with established lesions prior to a regression attempt were placed on a 0.05% cholesterol diet and observed up to 60 months. Weighted average cholesterols ranged from 235 to 587 mg/100 ml during the regression attempt. A control fed for the entire period of the experiment, 75 months, had an average weighted cholesterol of 435 mg/100 ml. We failed to obtain regression of atherosclerotic plaques in spite of reduction of serum cholesterol from high to moderate levels. The lesions in the experimental animals contained less lipid and more collagen and calcium than occurred in the control. Complicated plaques with aneurysm formation, stenosis of the distal aorta, and gangrene of the tail were also noted.
Atherosclerosis 1977 Jul
PMID:Failure of regression of atherosclerosis in dogs with moderate cholesterolemia. 90 27

Aortic tissues consisting of all three tunics were removed from normal adult rabbits and cultured in a semisynthetic gelosed medium supplemented by 10% serum obtained either from normal or hypercholesterolemic rabbits. Fibrillar cross-striated aggregates appeared with a high frequency (50%) in the extracellular space of explants cultured from four to eight days in medium supplemented by serum from hypercholesterolemic rabbits, but did not appear in explants cultured in serum from control animals (3%). The electron-dense segment was ruthenium red positive and digested by testicular hyaluronidase. The electron-lucent segment, composed of ruthenium red negative thin filaments, was not modified after hyaluronidase treatment but was strongly digested after collagenase treatment. It is believed that this material was fibrous long spacing collagen synthetized under culture conditions, as shown after tritiated proline incorporation.
Atherosclerosis 1977 Sep
PMID:Fibrous long spacing collagen in aortic explants of normal rabbit cultured in hypercholesterolemic serum. 91 68

The endothelial surface of the vessel wall was studied after various period of recirculation following transitory mechanical hypoxia. The acute changes consisted of partial or total destruction of the endothelium in certain areas. Later on, the regeneration (division and process-formation) of endothelial cells took place over the damaged areas. These events were demonstrated both by transmission and scanning electron microscopy. When severe vessel damage occurred, the subendothelial matrix, collagen and elastic fibres, and the stomata were also set free. Blood cells anchored to these areas were later covered by endothelium. Regeneration was practically complete after 10 days; previously only some small endothelial processes had shown evidence of regenerative activity. In spite of the extensive damage to the endothelium, no occluding thrombus formation was seen. The phagocytes functioned only in removing debris, and the thrombocytes in facilitating endothelial overgrowth.
Atherosclerosis
PMID:Scanning (SEM) and transmission (TEM) electron-microscopic studies on post-ischemic endothelial lesions following recirculation. 94 18

Male adult New Zealand rabbits were fed a 2% cholesterol diet for 30 of 60 days in order to determine the effect of hypercholesterolemia on aortic collagen synthesis. Collagen synthetic activity was estimated by measuring tissue prolyl hydroxylase activity and the amount of tissue collagen was estimated by measuring tissue hydroxyproline levels. Following 30 or 60 days of feeding there was a significant increase in both tissue and serum cholesterol indicating the onset of hypercholesterolemia. Measurement of collagen synthetic activity and tissue collagen levels demonstrated no increase over control tissues. These data therefore indicate that hypercholesterolemia is not a direct stimulus of tissue collagen synthetic activity.
Atherosclerosis
PMID:Hypercholesterolemia and aortic collagen synthesis in rabbit aortas. 94 16

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

A comparison between a normal and a Marfan's disease aortic valve has been attempted in terms of their tissue stress-strain characteristics and their histology. The diseased valve tissue was found to be more compliant by an order of magnitude than the normal valve, which is related to the disorientation of its collagen fibers, and the proliferation of mucopolysaccharides.
Atherosclerosis
PMID:Mechanical and histological study of aortic valve tissue from a patient with Marfan's disease. 94 28

In 47 patients with atherosclerosis of the coronary arteries the concentration of the blood serum free oxyproline was up by comparison with the normal figure and it depended not so much on the stage of the disease, but rather upon the character of hyperlipoproteinemia. A higher oxyproline concentration was revealed in the blood serum of patients presenting the IIb and IV types of hyperlipoproteinemia. The results of experimental investigations suggest that the activation of the glucocorticoid function of the adrenal cortex in patients with atherosclerosis of the coronary arteries results in a more intensive catabolism of the vascular wall collagen and in attending it rise of the blood serum free oxyproline concentration.
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PMID:[Free hydroxyproline content of the blood serum in patients with coronary arteriosclerosis]. 96 41


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