ISSN:1049-8834    

出版商:OVID    

年代:1991

数据来源: OVID

ISSN:1049-8834    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Rabbits fed a 1% cholesterol diet with or without the antioxidant butylated hydroxytoluene (BHT) developed typical atherosclerotic lesions. The addition of BHTgave higher levels of total cholesterol (+40%), triglycerides (+250%), low density lipoprotein (LDL), and very low density lipoprotein (VLDL) in plasma. Despite the lower plasma lipid levels, the degree of atherosclerosis of the aortic surface was considerably higher in rabbits fed cholesterol than in the group treated with cholesterol and BHT. The mean atherosclerotic involvement was 18.6 ±4.4% in the former group and 5.9±1.7% in the latter group (p=0.02). In all animals, there was a high correlation between the area of the arterial lesion and cholesterol content (r=0.96). Serum levels of cholesterol autooxidation products (7-ketocholesterol and cholesterol 5α, 6α-epoxide) were lower in the group of rabbits treated with BHT (p<0.005). Serum levels of vitamin E were slightly higher in the BHT group. There was no significant difference in the clearance of β-VLDL between the two treatment groups after using either 0-VLDL from cholesterol-fed animals or β-VLDL from BHT-fed animals. The results are in accord with the contention that oxidative modification of lipoproteins is important for the development of atherosclerosis and that antioxidants may have a protective effect At present, however, other explanations cannot be completely excluded, for example, effects of antioxidants on immunologic factors or monocyte adhesion.

ISSN:1049-8834    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

We determined the effect of estrogen and progesterone on plasma cholesterol and lipoprotein cholesterol concentrations and on arterial lesions in 24 ovariectomized and hysterectomized baboons fed a high-cholesterol/high-saturated-fat diet These baboons were divided into four groups: untreated control (C); estrogen, 100 μg/kg/week injected l.m. (E); progesterone, 3 mg/kg/day (P); and estrogen plus progesterone (E+P). The treatment regimen continued for 18 months. Cholesterol levels in plasma and lipoproteins were measured before hormone treatment and at 3, 10, and 18 months of treatment Postheparin plasma lipoprotein lipase (LPL) activity was also measured during the treatment After 18 months of hormone treatment, baboons were necropsied and arterial lesions were measured. Hormone treatment significantly influenced plasma cholesterol (P>C>[E+P]>E) and very low density lipoprotein plus low density lipoprotein (VLDL+LDL) cholesterol (P>C> [E+P] >E), with very little effect on high density lipoprotein (HDL) cholesterol concentration. The E+P group had a significantly higher HDL cholesterol concentration than did the P group. The (VLDL+LDL)/HDL cholesterol ratios in the E and E+P groups were significantly lower than those in the P and C groups. LPL activities were significantly lower in the E group compared with those in the E+P and P groups. Hormone treatment significantly influenced lesions in four (innominate, carotid, iliac, and abdominal aorta) of seven arteries. The P group had the most fatty streaks, and the E+P group had the least Multiple regression analysis suggested that hormone treatment influenced arterial lesions, both through effects on VLDL+LDL cholesterol and (VLDL+LDL)/HDL cholesterol ratio and through an effect independent of lipoproteins.

ISSN:1049-8834    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Lipoprotein(a) (Lp[a]) is a low density lipoprotein particle that contains plasminogen-like apolipoprotein(a). Recent studies suggest an association of Lp(a) with atherosclerotic vascular disease. We have studied the accumulation of Lp(a) hi atherosclerotic arteries of monkeys with diet-induced atherosclerosis. Immunohistochemistry with monospecific Lp(a) antisera revealed striking accumulations of Lp(a) in atherosclerotic coronary artery lesions. There was no Lp(a) in the normal, nonatherosclerotic arteries. Analysis of paired tissue and serum samples from 17 male hyperlipoproteinemic monkeys revealed a significant correlation between aortic wall Lp(a) and serum Lp(a) levels. The serum cholesterol level failed to correlate with either aortic Lp(a) or serum Lp(a). These results add further evidence for the potential role of Lp(a) in the pathogenesis of atherosclerosis.

ISSN:1049-8834    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

A dose-response study of dietary fish oil supplementation on platelet adhesion was performed in three groups of five normal individuals each. Fish oil equivalent to 3, 6, or 9 g eicosapentaenoic acid (£PA)/day was administered for 3 weeks, and platelet adhesion was evaluated under high and low shear rate conditions in a laminar flow chamber before, during, and after termination of fish oil administration. Platelet adhesion to collagen I and fibrinogen, the two test surfaces in this study, was greatly reduced in response to fish oil. The inhibitory effect was similar whether platelet adhesion was evaluated at high or low shear rates. Maximal inhibitory activity was noted at 6 g EPA/day. A delayed onset and prolonged washout period characterized the response. The washout period of the fish oil effect was inversely related to the level of dietary supplementation. Measurement of total fatty acid distribution in platelets showed a dose-related increase in n-3 polyunsaturated fatty acids. From these studies, it is concluded that fish oil is an effective inhibitor of platelet adhesion, which reaches its maximum effect at approximately 6 g EPA/day.

ISSN:1049-8834    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Polyunsaturated fatty acids in vegetable (n-6) and marine (n-3) oils have been shown to reduce cholesterol levels in normolipidemic individuals. However, there is relatively little information available on the lipoprotein responses to dietary n-6 and n-3 fatty acids in individuals with genetic forms of hyperlipidemia at risk for premature cardiovascular disease. We studied five subjects with heterozygous familial hypercholesterolemia (FH), as well as five normal controls, on three rigidly controlled diets differing primarily in their fatty acid composition. FH subjects reduced their total plasma cholesterol by 34% during the n-3 diet and by 26% with the n-6 diet (both p<0.001) when compared with values while on a butter diet In addition, low density lipoprotein (LDL) cholesterol fell 31% and 29% (bothp<0.001), and apolipoprotein B (apo B) levels dropped 28% and 27% (both p<0.01) during the n-3 and n-6 diets, respectively. A significant reduction of total and LDL cholesterol as well as of apo B was also noted in normal controls during n-3 and n-6 diets. Total plasma triglyceride and high density lipoprotein cholesterol fell significantly during n-3 diets in normal and FH subjects. Thus, FH and normal subjects respond in a similar fashion to diets low in saturated fatty acids and rich in n-3 and n-6, with decreased LDL cholesterol and apo B concentrations.

ISSN:1049-8834    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Net mass transfer of lipids was measured in plasma from fasted, normolipidemic subjects. The plasma was incubated, and lipoproteins were subsequently separated by polyanion precipitation or density gradient ultracentrifugation. Total cholesterol, unesterified cholesterol, and triglycerides were measured in the isolated lipoprotein fractions. The rate of cholesterol esterification was measured simultaneously. All plasma samples showed an increase in high density lipoprotein (HDL) cholesteryl esters during 1-hour incubations. In most cases, this increase was higher than the cholesteryl ester formation in total plasma due to cholesterol esterification. Therefore, we concluded that a net mass transfer of cholesteryl esters occurred from the very low plus low density lipoprotein (VLDL+LDL) fractions to HDL in plasma from most of the subjects studied. Transfer of triglycerides occurred from VLDL+LDL to HDL in plasma from all subjects. The cholesteryl ester transfer (measured after 1 hour) is not related to the activity of cholesteryl ester transfer protein. Inhibition of cholesterol esterification did not change the direction of cholesteryl ester or triglyceride transfer. Ultracentrifugal separation of plasma lipoproteins revealed that both HDL and VLDL are acceptors of cholesteryl esters and that VLDL donates triglycerides to both LDL and HDL. Removal of VLDL from plasma by ultracentrifugation did not affect the cholesteryl ester transfer from LDL to HDL. We conclude that LDL may act as a donor of cholesteryl esters during incubation of normolipidemic plasma.

ISSN:1049-8834    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

The fractional rate of cholesterol esterification in very low density lipoproteinand low density lipoprotein-depleted plasma (FERHDL) was studied in normolipidemic subjects and in individuals with hyperlipidemia and proven coronary artery disease (CAD). The FERHDLwas significantly higher than the FER in whole plasma and was significantly higher in normal men than in normal women. In addition, men and women with primary hyperlipidemia had significantly higher FERHDLvalues relative to their sex-matched controls. The most significant increases in FERHDLvalues, however, were observed in individuals with CAD. In all patient groups, FERHDLwas positively correlated with plasma triglyceride concentration. In addition, FERHDLwas negatively related to plasma high density lipoprotein (HDL) cholesterol concentration in all groups except in men with CAD and in normolipidemic women. The gradient gel electrophoretic pattern of HDL from individuals with either low or high FERHDLvalues indicated an inverse relation between this activity and the relative amount of HDL2bparticles. FERHDLlikely reflects the metabolic properties of the heterogeneous population of HDL particles in the plasma and may be a function of the relative content of larger and smaller HDL particles. It appears to be a sensitive and reliable functional measure of the particle size distribution in the HDL pool and one of potential clinical value in the assessment of risk for CAD.

ISSN:1049-8834    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

By equilibrium density gradient ultracentrifugation, we analyzed the chemical composition and particle size of low density lipoproteins (LDLs) in 16 subtractions separated from the LDL fractions (1.019 <d< 1.063 g/ml) of two hyperalphalipoproteinemic patients who had a deficiency of cholesteryl ester transfer protein (CETP). The LDLs of these patients comprised a group of heterogeneous lipoprotein particles distributed almost equally in a wide density range from d=1.025 g/ml to d=1.053 g/ml, whereas LDLs from normal controls were a homogeneous group of lipoprotein particles distributed in a narrow density range from d=1.030 g/ml to d=1.046 g/ml. The LDL in each subtraction derived from the patients' plasma samples was poor in cholesteryl ester and rich in trigrycerides and apolipoproteins. Each subtraction of normal control LDL contained only one species of homogeneous LDL particles, which progressively decreased in size with an increase in the density of the fraction. In contrast, each subtraction of patient LDL contained two species of LDL particles: smaller LDLs existed, in addition to those that were found to be identical to the normal control LDL particles observed in the corresponding subtractions. The intermediate density lipoproteins of the two patients were also composed of two species of lipoproteins. From these results, we speculate that two metabolic pathways may exist in the LDL formation process. In this process, the transfer of cholesteryl ester from high density lipoproteins by CETP may convert the smaller lipoprotein particles to the larger ones, forming the homogeneous LDL species.

ISSN:1049-8834    

出版商:OVID    

年代:1991

数据来源: OVID