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

Using a wide complex of biochemical indices 166 patients with cerebral atherosclerosis were examined. It was shown that in this disease regardless of the period of acute stage a deficiency of the brain circulation of physicochemical changes of the serum proteins, lipoproteins and an oppression of the process of cholesterol exterfication precede quantitative accumulation of total cholesterol in the blood, beta-lipoproteins, a decrease of the lecethin level and changes of protein fractions. Heparin treatment along with improvement of the patients' clinical state, indices of general and brain hemodynamics decreased a free cholesterol level, increased the strength of cholesterol and apoprotein relationship and phosphorolipid content in the blood. In the author's opinion one of the leading causes of lipoprotein metabolic disorders in atherosclerosis can be a change of hormonal regulation of the activity in proteins enzymes of the organs and tissues, including the enzymes regulating an oxidation-reduction process in the organism. The significance of the studied indices for diagnosis and medical labour examination is considered.
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PMID:[Disorders in lipoprotein metabolism indices in cerebral atherosclerosis, their importance for diagnosis and medical-occupational expertise]. 19 59

Hypertriglyceridemia, a risk factor for premature atherosclerosis, may result from decreased use of plasma triglycerides by tissues. The removal of triglycerides is mediated by the enzyme lipoprotein lipase (LPL). Heparin releases LPL from tissues and post-heparin plasma lipolytic activity (PHLA) has been extensively used to elucidate the mechanism of hypertriglyceridemia in various diseases. There is evidence to show that postheparin plasma contains enzymes other than LPL. Hence data on total PHLA are difficult to interpret. Availability of assays for the LPL component of PHLA has clarified equivocal findings in certain hypertriglyceridemic states. However, the LPL component is also heterogeneous. The LPL "isoenzymes" from various extrahepatic tissues behave differently under various metabolic conditions. Therefore, to understand properly the LPL system it is necessary to study the specific tissue LPL. Furthermore, the serum activator for LPL is now characterized. Its importance is evidenced by the recent discovery of a hypertriglyceridemic patient deficient in this apoprotein.
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PMID:The lipoprotein lipase system: new understandings. 20 4

In this study we have investigated, in four normal males the effects of dietary saturated and polyunsaturated fat on the chemical composition and thermotropic properties of human high density lipoproteins (HDL) and have measured the influence of the diets on the metabolism of that fraction of HDL apolipoprotein A-I (apoA-I) that undergoes exchange in vitro and accounts for approximately two-thirds of the lipoprotein's apoA-I complement. When compared with the saturated fat diet, the polyunsaturated diet reduced plasma cholesterol (24%, P < 0.01) by affecting the cholesterol content in the very low density lipoprotein ( downward arrow25%, P < 0.02), low density lipoprotein ( downward arrow20%, P < 0.01), and high density lipoprotein fractions ( downward arrow33%, P < 0.01). Plasma triglyceride was also lowered (by 13%, P < 0.01). Furthermore, polyunsaturated fat ingestion caused a significant fall in the palmitate and stearate content of HDL triglyceride (41 and 37%, respectively), cholesteryl esters (29 and 35%), and phospholipids (17 and 9%) with a concomitant increase in the linoleate content of these moieties (157, 28, and 29%, respectively). The polyunsaturated diet also produced reciprocal changes in the percentage protein ( downward arrow9%, P < 0.02) and phospholipid ( downward arrow11.5%, P < 0.01) in HDl. These compositional changes were associated with an increase in the microscopic fluidity of the polyunsaturated HDL, although both diets had little effect on the fluidity parameters of HDL at body temperature. Rate zonal ultracentrifugation indicated that the HDL(2)/HDL(3) ratio fell by 28% (P < 0.05) on the polyunsaturated fat diet. In addition to the above, this diet reduced plasma apoA-I by 21% (P < 0.01). No change was seen in the fractional catabolic rate or the distribution of the apoprotein between intravascular and extravascular compartments on the two diets. However, when compared with the saturated diet, the synthetic rate of apoA-I was reduced by 26% during polyunsaturated fat feeding. The results show that polyunsaturated fat alters the chemical composition, thermotropic properties, and subfraction distribution of HDL without changing the fractional rate of catabolism of their major protein, apoA-I.These findings deserve careful consideration in determining the applicability and efficacy of polyunsaturated fat diet therapy in the prevention of atherosclerosis in man.
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PMID:Effects of dietary polyunsaturated and saturated fat on the properties of high density lipoproteins and the metabolism of apolipoprotein A-I. 20 39

A simple procedure has been devised to give virtually pure preparations of polymorphonuclear leucocytes. This has permitted study of the regulation of cholesterol biosynthesis at cell level. Freshly isolated cells from donors with various forms of hyperlipoproteinaemia have been shown to have very low levels of cholesterol synthesis, presumably due to high circulating levels of apoprotein-B in donor plasma [1]. The activity of the rate-limiting enzyme for cholesterol biosynthesis, 3-hydroxy-3-methylglutaryl coenzyme A reductase, rapidly increases as the cells are incubated in lipoprotein-deficient medium, until, by 12 h, cells from patients heterozygous for familial type IIa hypercholesterolaemia are clearly distinguished from other hyperlipoproteinaemias. The possible significance of this finding is discussed in relation to the causation and treatment of atherosclerotic disease.
Atherosclerosis 1978 Mar
PMID:Regulation of cholesterol synthesis in the hyperlipoproteinaemias. Polymorphonuclear leucocyte abnormality specific to familial type II hypercholesterolaemia. 20 84

The serum decay and tissue distribution of iodine-labeled high density lipoprotein (HDL)-apoproteins were measured in rats 2--8 h after partial hepatectomy or sham-operation. A method was developed allowing continuous bloodsampling without using anticoagulantia or anaesthetics. The serum decay of HDL-apoproteins was biexponential. Neither the initial rapid phase (t 1/2 0.3 +/- 0.1 h), nor the slow phase (t 1/2 6.2 +/- 0.3 h) were influenced by the removal of 2/3 of the liver and consequently there was no effect on the fractional catabolic rate (F.C.R.: 2.9 +/- 0.2/day). The level of circulating HDL was decreased by partial hepatectomy but the chemical composition of HDL was unchanged. Total tissue HDL radioactivity in the control rats was 5.7, 2.8, 2.7, 1.0, 0.7, 0.2, 0.4 and 0.1% of the injected dose for skeletal muscle, adipose tissue, liver, jejunum, kidneys, spleen, lungs and heart, respectively. Only the value for liver was affected significantly by partial hepatectomy (0.6%). It is concluded that the in vivo degradation rate of HDL-apoproteins is not influenced by the removal of 2/3 of the liver and that the decrease in serum HDL concentration is due to an impaired rate of hepatic synthesis. These results indicate the possiblity of extrahepatic HDL-apoprotein catabolism or a stimulation of HDL-apoprotein degradation, induced by partial hepatectomy, in the remaining liver lobes.
Atherosclerosis 1978 Apr
PMID:High density lipoprotein catabolism before and after partial hepatectomy. 20 88

A 1,500 Cal test meal was used to study in man the apoprotein B-carbohydrate content and composition of VLDL, IDL and LDL in relation to the variation of plasma lipids and lipoproteins and the VLDL-apoprotein composition. Three essential facts emerge from the study: (1) the mirror image (inverse significant correlation) between VLDL-apo B plasma concentration and N-acetylglucosamine content of apo B; (2) a reduction in total carbohydate concentration of VLDL- and LDL-apo B, 2--4 h after the test meal and a trend to a reduction in the mannose content; (3) a significant correlation between sialic acid and apoprotein B concentration in plasma LDL during fasting. The effect of diet and subsequent fasting on carbohydrates of lipoproteins and the consequence of such changes on lipoprotein uptake are briefly discussed.
Atherosclerosis 1978 Aug
PMID:Relationship between the carbohydrate content of apoproteins of VLDL, IDL, and LDL and the plasma level of these lipoproteins in man. Short dietary effect. 21 83

VLDL of fasting serum was fractionated into 4 fractions of decreasing particle size by preparative ultracentrifugation in a density gradient from a patient with massive type V hyperlipoproteinaemia before and after treatment with 12 g daily of nicotinic acid. Serum triglycerides fell from 58 to 9 mmol/1 in response to treatment due particularly to reduction of larger VLDL particles. Total, insoluble (apoprotein B) and soluble protein of all VLDL fractions also fell but the ratio of these 3 protein fractions to triglyceride rose particularly in the smaller VLDL fractions. The relative amount of apolipoprotein CII increased in all fractions and the ratio apo CII to triglycerides increased by 60--90% in all VLDL fractions. The relative amounts of apo CI, apo CII-2 and apo E appeared also to increase. The results are consistent with the hypothesis that low amounts of apo CII may play a role for the development of hypertriglyceridaemia.
Atherosclerosis 1978 Sep
PMID:Relative increase in apolipoprotein CII content of VLDL and chylomicrons in a case with massive type V hyperlipoproteinaemia by nicotinic acid treatment. 21 88

We determined serum high-density lipoprotein cholesterol content and analyzed the approtein structure of the various lipoprotein fractions in 21 patients on chronic hemodialysis. High-density lipoprotein cholesterol was significantly reduced in all patients as compared with 11 normal persons (mean +/-1 standard deviation: 26 +/- 13 vs. 52 +/- 9 mg per 100 ml; P less than 0.001) whether or not triglyceride levels were raised. In seven of those with Type IV hyperlipoproteinemia, protein content of high-density lipoprotein and its subfractions 1, 2 and 3 were also reduced (P less than 0.001) in parallel with reductions in cholesterol in these fractions. Apoprotein electrophoresis showed an increase in "arginine-rich" peptide in very-low-density lipoprotein and high-density lipoprotein fraction 1, and a reduction in apoprotein Cll in very-low-density and high-density lipoprotein. In addition to their reduced high-density lipoprotein cholesterol levels, a major factor in the atherosclerosis of these patients may be their abnormal high-density lipoprotein composition. Their raised triglyceride levels could be due to defective lipoprotein lipase activation by the reduced very-low-density lipoprotein apoprotein.
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PMID:Defective high-density lipoprotein composition in patients on chronic hemodialysis. A possible mechanism for accelerated atherosclerosis. 21 15

The fasting serum concentrations of total cholesterol, low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), total triglyceride and apoprotein A1 were measured at intervals of 12-18 weeks for 60 weeks in 17 male and 11 female healthy young adults in order to assess the variability of these risk factors for coronary disease. No statistically significant seasonal changes were detected in any variable in either sex, although a progressive rise in apoprotein A1 concentration was observed. The coefficients of variation for random fluctuations with time were in the rank order: total cholesterol less than HDL-C less than apoprotein A1 less than LDL-C less than triglyceride. These differences were attributable to biological, rather than to methodological, factors. Within subjects, HDL cholesterol concentration varied inversely with triglyceride concentration and directly with apoprotein A1 concentration. The marked differences which exist in the biological variability of lipid risk factors for atherosclerosis need to be taken into account when making comparisons in epidemiological studies of the predictive powers of single on-entry measurements for future disease. Fluctuations of HDL-C with time appear to be related in part to variations in triglyceride-rich lipoprotein metabolism.
Atherosclerosis 1979 Sep
PMID:A longitudinal study of the biological variability of plasma lipoproteins in healthy young adults. 22 31

High density lipoprotein (HDL) was fractionated by ion exchange column chromatography using a continuous NaCl gradient of 0.06--0.13 M. It was found that, on the basic C apoprotein content, HDL is comprised of 3 subfractions. All 3 subfractions contain apo A-I and apo A-II but the apo A-I/apo A-II ratio is different in each subfraction and in the case of subfraction c, that fraction which eluted at highest NaCl concentrations, the A-I/A-II ratio varied even within this subfraction. Subfraction a contained no C apoprotein, subfraction b contained apo C-II and apo C-III-1 but no apo C-III-2 while subfraction c contained apo C-III-2 and trace amounts of apo C-II and C-III-1. Analysis of HDL2 and HDL3 shows that both contain all 3 lipoprotein subfractions, but in differing quantities.
Atherosclerosis 1979 Aug
PMID:Protein content and composition of human high density lipoprotein subfractions. 22 80


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