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

Cholesterol ester hydrolase activity was determined in preparations of rabbit and guinea pig aorta utilizing micellar and glycerol-dispersed cholesterol oleate substrates. Both substrate preparations demonstrated an acid pH optimum of 4--5 for the soluble and particulate rabbit media cholesterol ester hydrolase, suggesting a lysosomal origin for this activity. Approximately one-fifth of the total recovered activity was particulate. Particulate media preparations from guinea pig aorta also demonstrated cholesterol ester hydrolase activity at acid pH values with a definite optimum at pH 5 for the glycerol-dispersed substrate. However, in contrast to the rabbit media enzyme, activity was also observed at neutral pH with another optimum at pH 7. The supernatant enzyme from guinea pig media exhibited only a single pH optimum of 7. Cholesterol ester hydrolase activity from either rabbit or guinea pig media was not influenced by preincubation with cyclic AMP, ATP and protein kinase. The addition of chloroquine resulted in the inhibition of both the rabbit and guinea pig enzyme. Cholesterol ester hydrolase activity from rabbit and guinea pig media was also inhibited by phenyl methane sulfonyl fluoride; activity measured at pH 7 (guinea pig) was more sensitive to inhibition than activity measured at pH 5 (guinea pig and rabbit).
Atherosclerosis 1978 Sep
PMID:Characterization of cholesterol ester hydrolase activities in rabbit and guinea pig aortas. 3 Apr 61

Some important enzymes concerned with the biosynthesis of the precursors of glycosaminoglycans (gg), degradation of gg and biological sulphation have been studied in rats fed an atherogenic diet. L-Glutamine-D-fructose-6-phosphate amino-transferase and glucosamine-6-phosphate-N-acetylase--2 enzymes concerned with the biosynthesis of hexosamine precursors of gg--decreased in the liver in rats fed the atherogenic diet. UDPG pyrophosphorylase, UDPG dehydrogenase and UDPG glucuronic acid-5'-epimerase, which are concerned with the biosynthesis of the uronic precursors of gg, also decreased in the liver in the diet-fed rats. The activities of some of the enzymes concerned with degradation of gg-hyaluronidase, beta-glucuronidase beta-hexosaminidase, cathepsin and aryl sulphatase--increased both in the liver and aorta. The hepatic concentration of PAPS significantly decreased in the diet-fed rats. The sulphate-activating system, which includes ATP sulphurylase, APS kinase and sulphotransferase, also decreased. Thus the overall picture is one of decreased synthesis of gg and their increased degradation in the atheromatous rats.
Atherosclerosis
PMID:Metabolism of glycosaminoglycans in atheromatous rats. Enzymes concerned with synthesis, degradation and sulphation of glycosaminoglycans. 12 76

Sarcoplasmic reticulum (SR) fragments from the skeletal muscles of rabbit with marked atherosclerosis possessed decreased Ca2+-accumulating capacity. Lowering of transport efficiency, namely reduction of the Ca/ATP ratio from 1.9--normal value--to 0.9 during the experiment at 26 degrees C was accompanied by activation of Ca-ATPase and simultaneously of the rate of Ca2+ outflux from the SR. Arrhenius plots of Ca-ATPase temperature dependence characterized under normal conditions by a break at 20--21 degrees C was linearized under hypercholesterolemia. At the same time there was a rise (from 0.03 under normal conditions to 0.15 in atherosclerosis) of cholesterol/protein ratio in the SR membrane preparations. Activation energy for Ca-ATPase crude membranes under normal conditions was equal to 15.6 and 28.7 kcal/mol above and below the break point respectively; this value for Ca-ATPase of membranes with increased cholesterol level was 19 kcal/mol for all the temperatures investigated.
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PMID:[Several properties of the Ca-pump of rabbit skeletal muscle sarcoplasmic reticulum in hypercholesteremia]. 15 Feb 94

The oxygen and glucose uptake, lactate formation, ATP/ADP and NADH/NAD ratios and incorporation of [14C]acetate and [14C]linolenic acid into lipids of early fatty streaks and more advanced complicated atherosclerotic lesions of human aorta were determined during aerobic and hypoxic incubation. Compared with grossly normal appearing sections of the aorta in intima and media preparations of early fatty streaks the oxygen uptake was increased while that in further developed atheroma was slightly diminished. Under aerobic incubation conditions the metabolic state of fatty streaks and atheroma was characterized by increased lactate formation, NADH/NAD ratio and incorporation of [14C]acetate and [14C]linolenic acid into the lipids, but by a lowered ATP/ADP ratio. More pronounced changes in these metabolic parameters were observed when the aortic tissue segments were incubated under hypoxic conditions. The analysis by argentation TLC of fatty acid methylesters derived from total lipids of aerobically incubated fatty streaks revealed an increased incorporation of [14C]acetate into the highly unsaturated long-chain fatty acids. In developed atherosclerotic lesions and in hypoxia the incorporation of radioacetate into the polyunsaturated fatty acids and the formation of 20:4 fatty acid from [14C]linolenic acid were, in contrast to the above finding, decreased while the synthesis of eicosatrienoic acid was increased. This finding suggests a block in the desaturation step of linoleic into 20:4 fatty acid in further developed atheroma and in hypoxia. In aerobically incubated atherosclerotic lesions and in hypoxia the palmitic acid was synthesized mainly by chain elongation while in grossly normal areas of the aorta at least part of this acid was synthesized de novo.
Atherosclerosis 1976 Sep
PMID:Comparative studies on fatty acid synthesis in atherosclerotic and hypoxic human aorta. 18 99

The hyperreactive arterial endothelial cells have been introduced in this paper. They are characterized by their ability to transport particles too large for the small holes of the internal elastic lamina locating underneath the endothelial cells, such as carbon particles with the similar size of LDL, floating beta-lipoprotein, Lp(a) and especially of VLDL, into the subendothelial space from the blood stream by their abnormally strong contracting and phagocytosis-like activity. Large particles such as carbon particles with a size of 200 to 700 angstrom are too large to penetrate further through holes of the internal elastic lamina from the subendothelial space to muscular layers of the arterial wall, resulting in stagnating for a long time in the subendothelial space, thus showing the atherogenic property of the hyperreactive arterial endothelial cells. Such endothelial cells appear spotty and streaky in the localized endothelial lining of predominantly susceptible parts to atherosclerosis in susceptible animal species such as rabbit, chicken, and rhesus monkey especially densely in their atheromatous lesions, but do not generally appear in non-susceptible animals to atherosclerosis like rate and dog. They are extremely few in infant rabbit, but increase by age.They appear in hypertensive rat, showing a characteristic distribution even in small groups of arteriessuch as the circle of Willis. Cyclic AMP, and especially dibutyryl cyclic AMP, exhibited an inhibitory effect on the hyperreactivity of those cells. Cyclic AMP phosphodiesterase inhibitors, EG467 and eg626, exhibited a powerful inhibitory effect on the contracting and phagocytosis-like activity of those cells, as in the case of pyridinolcarbamate, which enhances enzymes to produce ATP and inhibits slightly cyclic AMP phosphodiesterase, although its inhibitory effect on cyclic AMP phosphodiesterase is weaker than that of EF467 and EG626. The usefulness of the inhibitors on cyclic AMP phospodiesterase of arterial endothelial cells and platelets and on that of brain, such as EG467 AND EG626, has been suggested in the treatment of atherosclerotic disorders, especially of cerebral atherosclerosis. Some of the hitherto desperate mental disability of the aged seem to be a promising target for treatment with cyclic AMP phosphodiesterase inhibitors.
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PMID:Hyperreactive arterial endothelial cells in atherogenesis and cyclic AMP phosphodiesterase inhibitor in prevention and treatment of atherosclerotic disorders. 23 47

The activity of phosphofructokinase (PFK, 2.7.1.11) was measured in arteries of very young (5-8 week old) pigeons known to differ in susceptibility to atherosclerosis. The activity of the arterial enzyme was significantly higher in the atherosclerosis-susceptible White Carneau (WC) pigeons than in the resistant Show Racers (SR). The difference was significant whether enzyme activity was calculated on the basis of extract protein, DNA content or fat-free dry weight. In the White Carneau arteries the activity of the enzyme was higher in the female than the male pigeons. PFK is a key regulatory enzyme of glycolysis and is subject to fine control adjustments. A low ATP/ADP ratio and a fall in citrate concentration, as for example, induced by hypoxia, are meditors of a feedback mechanism leading to a rise in PFK activity and enhancement of glycolysis for energy production. This mechanism appears to be the cause of the higher PFK activity in the WC arteries, because related studies indicate impaired Krebs cycle activity in these vessels. It is suggested that the increased dependence of the WC arteries on glycolysis facilitates the development of atherosclerosis in this pigeon strain and that the mechanism is similar to the mechanism by which tissue hypoxia causes lipid accumulation and connective tissue alterations in the arterial wall.
Atherosclerosis
PMID:Elevation of arterial phosphorfuctokinase activity associated with susceptibility to atherosclerosis in pigeons. 23 61

Cholesterol esterification in the arterial wall was investigated with cell-free preparations of intima-media from control rabbits and rabbits rendered atherosclerotic by feeding a diet containing 1% cholesterol. In the presence of 2 mM ATP and 0.1 mM CoA, the major activity for esterification of [4-14C] cholesterol added in vitro was found in the 12,000 g and 105,000 g pellets. In control animals, the activity in the latter pellet was twice that in the former. After cholesterol-feeding for 6 months, the activity increased 5-fold in the 105,000 g pellet and 2-fold in the 12,000 g pellet of the atherosclerotic intima-media. Prostaglandin E2 (PGE2) in concentrations between 2 and 12 X 10(-7) M exhibited a dose-dependent inhibition of the esterifying activity in both particulate preparations. The inhibition was 97% at PGE2 concentrations greater than 1.2 X 10(-6) M in preparations from control animals. Inhibition by PGE2 in preparations from atherosclerotic rabbits was also observed. These results suggest a possible regulatory role of PGE2 in cholesterol esterification in the arterial wall.
Atherosclerosis 1977 Jun
PMID:Inhibition of cholesterol esterification in rabbit aorta by prostaglandin E2. 90 19

In fourty patients with peripheric atherosclerosis obliterans blood flow was measured by means of venous occlusion plethysmography during an intraarterial and an intravenous infusion of ATP. The intraarterial application showed a significantly higher increase of blood flow than the intravenous in the sick extremities. The "borrowing-lending-phenomenon" happened more seldom than after an intravenous load. This withdrawal of blood occurred most frequently in patients with proximal occlusions, when the infusion reached casually the arteria femoralis profunda only. The "borrowing-lending-phenomenon" can be measured by the poststenotic pressure and by the volume of blood flow in time. Then the patients complain about a begining or an increasing of an ischemic pain at rest.
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PMID:[Investigation by borrowing-lending-phenomenon under conditions of intraarterial induced vasodilatation (author's transl)]. 91 79

Enzymes of DNA synthesis, thymidine kinase (ATP-thymidine-5'-phospho-transferase, EC 2.7.1.21), DNA polymerase (EC 2.7.7.7) and nuclease activities were investigated in isolated purified nuclei of swine aorta. Thymidine kinase which is detectable in these nuclei can be stimulated by the addition of phospholipase C. DNA polymerase activity of isolated nuclei is strongly dependent on addition of an exogenous template; the preferred template is activated DNA. The activity in the absence of an added template is very low except when labelled dCTP is used as the precursor. This incorporation of labelled dCTP does not require the addition of the other three triphosphates, and under these conditions, dCTP seems to be incorporated into what may be a homopolymer. As with other tissues, solubilized preparations of aortic nuclei have two DNA polymerase activities which also prefer activated DNA template. There is no detectable endonuclease in aortic nuclei.
Atherosclerosis
PMID:Enzymes of DNA synthesis in isolated nuclei of swin aorta. 94 21

During neointima formation, which is an early and essential step in the development of atherosclerosis, endothelium-independent relaxations (nitroglycerin, 3-morpholinosydnonimine) are preserved, whereas muscarinic endothelium-dependent relaxation becomes impaired. The present study was undertaken to determine the selectivity of this impairment. The neointima was induced by positioning a nonocclusive, soft silicone collar around the left carotid artery of rabbits. The contralateral artery served as a control. Seven days later, vascular rings were mounted in organ chambers, contracted with phenylephrine (0.35 microM), and cumulative dose-relaxation curves were made. Intima-bearing vessels were less sensitive to acetylcholine, confirming the original observation. In contrast, the dose-relaxation curves for substance P and for the calcium ionophore A23187 were not altered in the presence of neointima. The curve for ATP was even shifted to the left. These results suggest that the nitric oxide synthase: cyclic GMP system remains intact in intima-bearing vessels and that the diminished endothelium-dependent relaxations are due to a selective alteration of the muscarinic receptors.
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PMID:Selective muscarinic alterations of nitric oxide-mediated relaxations by neointima. 128 71


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