Hypercholesterolemia-induced oxidative stress in heart and its prevention by vitamin E

Oxygen-free radicals have been implicated in hypercholesteolemic atherosclerosis. It is possible that hypercholesterolemia produces oxidative stress in myocardium. We therefore investigated the effects of a high cholesterol diet in the absence or presence of vitamin E on serum cholesterol and lipid peroxidation product malondialdehyde (MDA), chemiluminescence (M-CL), a measure of antioxidant reserve, and activity of antioxidant enzymes [superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-P_x)] in cardiac muscles of rabbits. Rabbits were divided into four groups: Group I, regular rabbit chow diet; Group II, same as Group I + vitamin E; Group III, high cholesterol diet; Group IV, high cholesterol + vitamin E. The heart was removed under anesthesia at the end of 4 months on their respective diets for various biochemical measurements. Serum cholesterol in Groups III and IV increased to a similar extent. There was an increase in the levels of MDA, M-CL, GSH-P_x activity and a decrease in SOD activity in hypercholesterolemic rabbits in the absence of vitamin E. Vitamin E prevented the hypercholesterolemia-induced changes in cardiac MDA, M-CL, and GSH-P_x. These results suggest that hypercholesterolemia produces oxidative stress in the myocardium which may be due to a decrease in the antioxidant reserve, and that vitamin E is effective in preventing hypercholesterolemia-induced oxidative stress on the myocardium.     

Suppression of hypercholesterolemic atherosclerosis by pentoxifylline and its mechanism

Reactive oxygen species (ROS) have been implicated in the development of hypercholesterolemic atherosclerosis. Hypercholesterolemia increases the levels of platelet activating factor (PAF) and cytokines which are known to stimulate granulocytes and endothelial cells to produce ROS. Pentoxifylline (PTX) is an inhibitor of cytokines and PAF and would reduce the generation of ROS by granulocytes and endothelial cells. PTX therefore would be expected to reduce the development of hypercholesterolemic atherosclerosis. New Zealand white female rabbits were assigned to four groups: Group I (n=12), control; Group II (n=5), PTX control (40 mg/kg body weight daily orally); Group III (n=13), 0.5% cholesterol; Group IV (n=9), 0.5% cholesterol+PTX (40 mg/kg body weight daily orally). Blood samples were collected before (0 time) and after 1 and 2 months on experimental diets for measurement of serum triglycerides (TG), total cholesterol (TC), LDL-C, HDL-C and serum malondialdehyde (MDA), a lipid peroxidation product. At the end of 2 months the aorta was removed for measurement of atherosclerotic plaques, MDA, and aortic tissue chemiluminescence (Ao-CL), a marker for antioxidant reserve. Rabbits in Group III developed atherosclerosis (56.61+/-6.90% of the intimal surface of aorta was covered with atherosclerotic plaques) which was associated with an increase in the serum TG, TC, LDL-C, HDL-C, TC/HDL-C, MDA and aortic MDA and antioxidant reserve. PTX reduced the development of atherosclerosis by 38.1% and this was associated with decreases in serum MDA by 32%, aortic MDA by 37%, and antioxidant reserve by 17.3% without changes in the serum lipids. These results suggest that ROS generated during hypercholesterolemia via cytokines and PAF may in part contribute to the development of hypercholesterolemic atherosclerosis and that suppression of production and activity of cytokines and PAF may reduce the development of hypercholesterolemic atherosclerosis.     

Hypocholesterolemic and antiatherosclerotic effect of flax lignan complex isolated from flaxseed

Hypercholesterolemia, low HDL-C and oxygen radicals have been implicated in the development of atherosclerosis. Lignan complex isolated from flaxseed contains secoisolariciresinol diglucoside (SDG), 3-hydroxy-3methylglutaric acid (HMGA) and cinnamic acids. SDG and cinnamic acids are antioxidants, and HMGA is a hypocholesterolemic agent. Antioxidants are known to reduce hypercholesterolemic atherosclerosis. The objectives of this study were to determine if lignan complex reduces (i) serum cholesterol, (ii) oxidative stress, and (iii) atherosclerosis in hypercholesterolemic rabbits. Rabbits were assigned to four groups: Group I, control; Group II, lignan complex control (lignan complex, 40 mg/kg body weight daily orally); Group III, 0.5% cholesterol; Group IV, 0.5% cholesterol diet+lignan complex, (40 mg/kg body weight daily orally). Blood samples were collected before (time 0) and after 1 and 2 months of experimental diets for measurement of serum triglycerides (TG), total cholesterol (TC), LDL-C, HDL-C and serum malondialdehyde (MDA), a lipid peroxidation product. At the end of the protocol, the aorta was removed for measurement of atherosclerotic plaques, MDA and aortic tissue chemiluminescence (Aortic CL), a marker of antioxidant reserve. Rabbits in Group III developed atherosclerosis (50.84+/-6.23% of the intimal surface of the aorta was covered with atherosclerotic changes) which was associated with an increase in the serum TG, TC, LDL-C, HDL-C, MDA and aortic MDA and antioxidant reserve. Lignan complex reduced the development of atherosclerosis by 34.37% and this was associated with a decrease in serum TC by 20%, LDL-C by 14%, TC/HDL-C by 34%, serum MDA by 35% and aortic MDA by 58%. Serum HDL-C was elevated by 30% in hypercholesterolemic rabbits and by 25% in normocholesterolemic rabbits with lignan complex. Lignan complex did not affect the TC and LDL-C and serum MDA in the normocholesterolemic rabbits. However, it increased the aortic MDA in the normocholesterolemic rabbits. These results suggest that lignan complex isolated from flaxseed reduced the extent of hypercholesterolemic atherosclerosis and this effect was associated with marked decreases in oxidative stress, serum total cholesterol, LDL-C and risk ratio, and elevation of serum HDL-C. Lignan complex may, therefore, be beneficial in preventing atherosclerosis, and reducing risk factors for coronary artery disease and stroke.     

Suppression of Oxidative Stress as a Mechanism of Reduction of Hypercholesterolemic Atherosclerosis by Cyclooxygenase Inhibitors

Hypercholesterolemia increases the formation of arachidonic acid from membrane phospholipids. Reactive oxgyen species (ROS) are generated during the synthesis of prostaglandins (PGs) from arachidonic acid. ROS have been implicated in the development of hypercholesterolemic atherosclerosis. Inhibition of the synthesis of PGs by indomethacin or naproxen, therefore, should be able to prevent the generation of ROS and hence the development of atherosclerosis. The objective of this study was to determine if indomethacin or naproxen reduces the development of hypercholesterolemic atherosclerosis and if this reduction is associated with decrease in the oxidative stress. Rabbits were assigned to 5 groups: Group I, control; Group II, indomethacin control (6 mg·kg body wt^–1·d^–1 PO); Group III, 0.5% cholesterol; Group IV, 0.5% cholesterol plus indomethacin (6 mg·kg body wt^–1·d^–1 PO); Group V, 0.5% cholesterol plus naproxen (10 mg·kg body wt^–1·d^–1 PO). Blood samples were collected before (time 0) and after 1 and 2 months of experimental diets for measurement of serum triglycerides (TG), total cholesterol (TC), LDL and HDL cholesterol (LDL-C, HDL-C), serum malondialdehyde (MDA), and white blood cell chemiluminescence (WBC-CL), a measure of ROS produced by WBC. At the end of the protocol, the aorta was removed for measurement of atherosclerotic plaques, MDA, an aortic tissue lipid peroxidation product, and aortic tissue chemiluminescence (Aortic-CL), a marker of antioxidant reserve. Serum TG, LDL-C, HDL-C and the ratio TC/HDL-C increased to a similar extent in Groups III, IV and V at months 1 and 2 compared with time 0. Indomethacin and naproxen had practically no effect on serum lipid levels. Serum MDA increased to a similar extent in Groups III and IV and to a greater extent in Group V compared with 0 time. WBC-CL activity was similar in the 5 groups. There was an increase in the levels of aortic-MDA in Groups III and IV as compared to Group I or II, the increase being smaller in Group IV than in Group III. Aortic MDA values in Group V were lower than those in all other groups. Antioxidant reserve increased in Groups III and V but remained unchanged in Group IV compared to Groups I or II. Indomethacin and naproxen reduced hypercholesterolemic atherosclerosis by 46.73% and 46.56%, respectively. Indomethacin and naproxen, the inhibitors of prostaglandin synthesis, reduced hypercholesterolemic atherosclerosis and this effect was associated with a decrease in the oxidative stress. These results suggest that ROS generated during synthesis of prostaglandins in hypercholesterolemia might in part contribute to the development of hypercholesterolemic atherosclerosis.     

Oxygen free radicals as a mechanism of hypercholesterolemic atherosclerosis: Effects of probucol

We investigated the effects of high cholesterol diet in the presence and absence of probucol on the genesis of atherosclerosis, the blood lipid profile, aortic tissue lipid peroxidation product malondialdehyde (MDA), and aortic tissue chemiluminescence (CL) a marker for antioxidant reserve in rabbits. Five groups each of 10 rabbits were studied: group I, regular rabbit chow; group II, as I + cholesterol (0.5%); group III, as I + cholesterol (0.5%) and probucol (0.5 gm/kg/day); group IV, as I + cholesterol (1%), and group V, as I + cholesterol (1%) and probucol (0.5 gm/kg/day). Blood concentrations of triglyceride (TG), total cholesterol (TC), high density lipoproteincholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C), very low density lipoprotein-cholesterol (VLDL-C) were measured at monthly intervals for 4 months. The aorta was removed at the end of the protocol for assessment of atherosclerotic changes (gross and microscopic), MDA concentration and CL. TC, LDL-C, LDL-C/HDL-C ratio increased in all the groups except group I, while VLDL-C increased in group II only. HDL-C decreased in groups III, IV and V but remained unchanged in groups I and II. There was a decrease in HDL-C and VLDL-C components and an increase in LDL-C components of total cholesterol in all the groups II, III, IV and V, the changes being greater in group IV than in group II. Probucol did not appreciably affect the changes in lipid profile except that it decreased HDL-C significantly. Aortic tissue MDA increased in groups II, IV and V to a similar extent. Aortic CL which was measured only in groups I, IV and V increased to similar extent in the latter two groups. Atherosclerotic changes were greater in group II than in group III but similar to that in groups IV and V. Histological changes were practically similar in groups II, III, IV and V. The increased levels of aortic MDA and CL, which were associated with development of atherosclerosis, suggest a role for oxygen free radicals in the pathogenesis of hypercholesterolemia-induced atherosclerosis. Protection afforded by probucol was associated with a decrease in aortic MDA in spite of hypercholesterolemia. Ineffectiveness of probucol in 1% cholesterolfed rabbits was associated with its inability to reduce MDA and increase antioxidant reserve. These findings further support for the hypothesis that oxygen free radicals are involved in the genesis and maintenance of hypercholesterolemic atherosclerosis.     

Regression of hypercholesterolemic atherosclerosis in rabbits by secoisolariciresinol diglucoside isolated from flaxseed

Secoisolariciresinol diglucoside (SDG) isolated from flaxseed is a lipid-lowering and antioxidant agent. It suppresses the development of hypercholesterolemic atherosclerosis in rabbits. It is however not known if SDG would produce regression of atherosclerosis. The objectives of this study were to determine (i) if SDG produces regression of atherosclerosis; (ii) if regression is associated with reduction in serum lipids, oxidative stress or both; and (iii) if the duration of treatment has an effect on regression. Rabbits were assigned to five groups: Group I, regular diet (control); Group II, 0.5% cholesterol diet for 2 months (mo); Group III, same as Group II but followed by regular diet for 2 mo; Group IV, same as Group II and followed by regular diet with SDG (20mg x kg body wt(-1) x day(-1) PO) for 2 mo; and Group V, same as Group IV but SDG treatment for an additional 2 mo. Blood samples were collected from rabbits before and at monthly intervals thereafter on their respective diet regimen for measurement of triglycerides (TG), total cholesterol (TC), LDL-C, HDL-C and malondialdehyde (MDA), a lipid peroxidation product. At the end of the protocol, the aorta was removed for assessment of atherosclerotic lesions, aortic MDA and aortic chemiluminescence (Aortic-CL), a measure of antioxidant reserve. MDA and Aortic-CL provide an index of oxidative stress. Increases in serum TG, TC, LDL-C, HDL-C and the risk ratio TC/HDL-C in Group II were associated with an increase in oxidative stress and development of atherosclerosis (57% of aortic intimal surface covered with lesions). Serum lipids decreased to a similar extent in Groups III-V, however atherosclerotic lesions were 84%, 63% and 44%, respectively in Groups III-V. There were more atherosclerotic lesions in Group III (+48.9%) as compared to Group II. The atherosclerotic lesions decreased by 24% and 45%, respectively in Groups IV and V compared to Group III. The reduction in atherosclerotic lesions was associated with a reduction in oxidative stress. These results suggest that (i) regular diet following a high cholesterol diet accelerates atherosclerosis in spite of a decrease in serum lipids; (ii) SDG treatment prevents the progression of atherosclerosis on a regular diet following a high cholesterol diet; (iii) prevention of progression is associated with a reduction of aortic oxidative stress and not with reductions in serum lipids; (iv) a longer duration of treatment reduces the progression of atherosclerosis to a greater extent, and tends to regress the atherosclerosis.     

Attenuation of the development of hypercholesterolemic atherosclerosis by thymoquinone

Thymoquinone (TQ), derived from Nigella sativa seed, is an antioxidant. The present study investigated whether TQ attenuates the development of atherosclerosis, and/or reduces the serum lipid levels and oxidative stress in rabbits. New Zealand white female rabbits were assigned to four groups of six animals each: group I, control; group II, 1% cholesterol diet; group III, 1% cholesterol plus TQ (10 mg/kg/day; through a nasogastric tube) diet; and group IV, 1% cholesterol plus TQ (20 mg/kg/day; through a nasogastric tube) diet. Blood samples were collected at baseline and after four and eight weeks on the experimental diets for measurement of serum lipids, total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), TC/HDL-C ratio and oxidative stress biomarkers (malondialdehyde [MDA] and protein carbonyls). At the end of the eight weeks, the aorta was removed for the assessment of atherosclerotic changes, MDA and protein carbonyls. Group II animals developed atherosclerosis (45%±11% of the intimal surface of aorta was covered with atherosclerotic plaques), which was associated with an increase in the serum TC, TG, LDL-C, HDL-C, TC/HDL-C, MDA and protein carbonyls. In group III, TQ decreased serum TC, LDL-C, MDA and protein carbonyls by 26%, 29%, 85% and 62%, respectively, and aortic MDA by 73%, which was associated with a 40% reduction of the development of aortic atherosclerosis. The higher dose of TQ in group IV had effects similar to the lower dose (group III), except that this dose further decreased serum TG. It is concluded that TQ attenuates hypercholesterolemic atherosclerosis and this effect is associated with a decrease in serum lipids and oxidative stress.     

Experimental atherosclerosis and oxygen free radicals

Oxygen free radicals are known to produce cellular injury by peroxidation of phospholipids in the cell membrane. These free radicals might damage the endothelial cell and thus set the stage for atherosclerosis. The authors studied the effect of high-cholesterol diets on the genesis of atherosclerosis and lipid peroxidation products, malondialdehyde (MDA) in rabbits. The animals were divided into four groups each comprising 5 rabbits, on the basis of their diets. Group I, control diet; group II, cholesterol; group III, coconut oil; group IV, a mixture of cholesterol, coconut oil, and cholic acid. Rabbits were sacrificed five months after being on the respective diets. Blood samples were obtained for the measurements of total cholesterol, high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), very low density lipoprotein cholesterol (VLDL-C), triglycerides, and MDA at the end of the protocol. The aortas were removed from different animals for the identification of atherosclerotic plaques. Plaques were detected in all the animals in group II and group IV. The serum total cholesterol, LDL-C, and VLDL-C were significantly higher in animals of group II and IV than in those of group I. The values for serum total cholesterol, HDL-C, LDL-C, and VLDL-C in group III were not significantly different from those in group I. The blood MDA and serum triglycerides were also higher in animals of group II and IV than in those of group I. There were, however, no significant differences in these parameters in group III as compared with those in group I.(ABSTRACT TRUNCATED AT 250 WORDS)     

Reduction of serum cholesterol and hypercholesterolemic atherosclerosis in rabbits by secoisolariciresinol diglucoside isolated from flaxseed

BACKGROUND: Secoisolariciresinol diglucoside (SDG) is a plant lignan isolated from flaxseed. Lignans are platelet-activating factor-receptor antagonists that would inhibit the production of oxygen radicals by polymorphonuclear leukocytes. SDG is an antioxidant. Antioxidants studied thus far are known to reduce hypercholesterolemic atherosclerosis. The objective of this study was to determine the effect of SDG on various blood lipid and aortic tissue oxidative stress parameters and on the development of atherosclerosis in rabbits fed a high-cholesterol diet. METHODS AND RESULTS: Rabbits were assigned to 4 groups: group 1, control; group 2, SDG control (15 mg. kg body wt-1. d-1 PO); group 3, 1% cholesterol diet; and group 4, same as group 3 but with added SDG (15 mg. kg body wt-1. d-1 PO). Blood samples were collected before (time 0) and after 4 and 8 weeks of experimental diets for measurement of serum triglycerides, total cholesterol (TC), and LDL, HDL, and VLDL cholesterol (LDL-C, HDL-C, and VLDL-C). The aorta was removed at the end of the protocol for assessment of atherosclerotic plaques; malondialdehyde, an aortic tissue lipid peroxidation product; and aortic tissue chemiluminescence, a marker for antioxidant reserve. Serum TC, LDL-C, and the ratios LDL-C/HDL-C and TC/HDL-C increased in groups 3 and 4 compared with time 0, the increase being smaller in group 4 than in group 3. Serum HDL-C decreased in group 3 and increased in group 4 compared with time 0, but changes were lower in group 3 than in group 4. SDG reduced TC and LDL-C by 33% and 35%, respectively, at week 8 but increased HDL-C significantly, by>140%, as early as week 4. It also decreased TC/LDL-C and LDL-C/HDL-C ratios by approximately 64%. There was an increase in aortic malondialdehyde and chemiluminescence in group 3, and they were lower in group 4 than in group 3. SDG reduced hypercholesterolemic atherosclerosis by 73%. CONCLUSIONS: These results suggest that SDG reduced hypercholesterolemic atherosclerosis and that this effect was associated with a decrease in serum cholesterol, LDL-C, and lipid peroxidation product and an increase in HDL-C and antioxidant reserve.     

The effect of ethanol extract of Hypericum lysimachioides on lipid profile in hypercholesterolemic rabbits and its in vitro antioxidant activity

Hypercholesterolemia, high cholesterol diet and oxidative stress increase serum total cholesterol and LDL cholesterol levels resulting in increased risk for development of atherosclerosis. Antioxidants play an important role in inhibiting and scavenging radicals, thus providing protection to humans against infectious and degenerative diseases. Literature shows that the antioxidant activity is high in medicinal plants. Realizing the fact that, this study was carried out to determine the effect of ethanol extract of Hypericum lysimachioides Boiss var lysimachioides (Guttifera) on serum lipid levels and serum lipid peroxidation in hypercholesterolemic rabbits. The rabbits were divided into four groups and these groups were fed with diets containing standard laboratory diet (Group I), standard laboratory diet and ethanol extracts of H. lysimachioides (HL) (50mg/kg body weight) (Group II), standard laboratory diet, ethanol extracts of HL (50mg/kg body weight) and cholesterol (100mg/kg body weight) (Group III), and finally standard laboratory diet and cholesterol (100mg/kg body weight) (Group IV), for 5 weeks. Feeding cholesterol increased serum cholesterol and LDL cholesterol levels significantly in Group IV as compared to the other groups. Ethanol extract of HL with high cholesterol diet significantly lowered LDL cholesterol and total cholesterol levels in the rabbits of Group III as compared to the Group IV. The level of serum triacylglycerol was found to be similar to all comparison groups. HDL cholesterol levels were also increased significantly in Groups II and III as compared to Group IV. Statistically significant difference was found in Group IV as compared to all other groups. The ethanol extract of HL with high cholesterol diet significantly lowered the serum MDA levels in the rabbits of Group III compared to the Group IV. The histopathological findings confirmed that the ethanol extract of HL restrained the progression of the hydropic degeneration and fatty changes in the liver and some atherosclerotic lesions in the aorta. The in vitro antioxidant activities of ethanol extract of HL was also evaluated. The free radical-scavenging properties of HL (IC(50)=28 microg/ml) were studied using 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay system. Since plant phenolic compound is one of the phytochemicals possessing radical scavenging activity, the amount of total phenolic compound was also determined in ethanol extract of HL and total phenolic content of one-milligram HL ethanol extract was equivalent to 307 microg of gallic acid. Total antioxidant activity of ethanol extract of HL was tested by using ferric thiocyanate (FTC) and thiobarbituric acid (TBA) methods. Antioxidative activities of ethanol extract of HL was found to be comparable with Vitamin E. In conclusion, the use of this extract could be useful in the management of cardiovascular disease in which atherosclerosis is important.     

Impaired plasma viscosity via increased cholesterol levels in peripheral occlusive arterial disease [correction of disase

The aim of this study was to investigate the relationship between plasma viscosity and lipoprotein and apolipoprotein pattern in normo- and hypercholesterolemic patients with peripheral occlusive arterial disease (POAD). 40 patients with POAD have been selected (8 females and 32 males, mean age: 54+/-3.2 years) with clinically evident superficial femoral occlusive artery disease. They were separated into two groups as normocholesterolemic (plasma total cholesterol <200 mg/dl) and hypercholesterolemic (plasma total cholesterol >200 mg/dl). Plasma total cholesterol, high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), triglycerides, total protein, and albumin levels were determined by enzymatic methods using commercial kits. Levels of apolipoprotein AI (apo AI), and apolipoprotein B (apo B) were measured using a immunoturbidometric method. Plasma viscosity (PV) was measured by capillary viscometer. Classifying the patients with PAOD according to the cholesterol levels; hypercholesterolemic (mean total-cholesterol: 227.90+/-26.97 mg/dl) patients had significantly higher LDL-C, PV and triglyceride levels compared with nornocholesterolemic patients (p<0.001, p<0.001, p<0.001, respectively). HDL-C and apo B were significantly lower in hypercholesterolemic patients than in normocholesterolemic patients (p<0.001, p<0.001, respectively). PV was positively correlated with total cholesterol (r=0.485, p<0.05), atherogenic index (r=0.624, p<0.01), total-C/HDL-C ratio (r=0.624, p<0.05), and LDL-C/HDL-C ratio (r=0.707, p<0.001) in hypercholesterolemic patients with POAD. PV was higher in hypercholesterolemic patients with POAD than in normocholesterolemic patients with POAD. We suggest that POAD patients should be regarded as a heterogenous group with lipid and lipoprotein parameters in order to assess the microcirculation in the affected limb. In case of dyslipidemia in POAD patients an elevated plasma viscosity should be considered as coexisting risk factor.     

Higher level of plasma cholesteryl ester transfer activity from high-density lipoprotein to Apo B-containing lipoproteins in subjects with angiographically detectable coronary artery disease

Background and hypothesis: Plasma high-density lipoprotein cholesterol (HDL-C) levels correlate inversely with the incidence of coronary artery disease. In order to ascertain whether the transfer activity is related to coronary atherosclerosis, we studied plasma cholesteryl ester transfer activity (CETA) from HDL to apo B-containing lipoproteins in a consecutive series of 64 Japanese men aged <60 years who had undergone diagnostic coronary angiography. Methods: The subjects were divided into two groups: those who had ≥50% luminal stenosis in one or more coronary arteries (Group 1) and those who had <50% stenosis (Group 2). Results: CETA was 20.8±6.0%/2h in 38 subjects in Group 1. significantly higher than 17.4±6.9%/2h in 26 subjects in Group 2(p<0.05). Plasma HDL-C levels in Group 1 were significantly lower than those in Group 2(p<0.05). CETA correlated inversely with HDL-C levels (r = ?0.46, p<0.001). Plasma total cholesterol, low-density lipoprotein cholesterol (LDL-C), triglyceride (TG), and Lp(a) levels did not differ significantly between the two groups. There was no significant correlation between CETA and either LDL-C or TG levels. Conclusion: Results suggest that high CETA is realted to low plasma HDL-C levels and may lead to the development of coronary atherosclerosis. Also, CETA was independent of plasma LDL-C or TG levels.     

Study of the correlation between blood lipid levels and the severity of coronary atherosclerosis in a Chinese population sample

OBJECTIVE: To investigate the relationship between blood lipid levels with severity of coronary artery atherosclerosis in a Chinese population sample. METHODS AND RESULTS: According to coronary angiography results, 363 patients (287 men and 76 women) with coronary artery atherosclerosis were divided into four groups: the single-vessel group (I, n = 125), the double-vessel group (II, n = 113), the triple-vessel group (III, n = 107) and the multi-vessel group (IV, n = 18).The severity of coronary artery atherosclerosis was quantified with a modified Gensini score on the basis of angiographic imaging. Serum triglycerides (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), non-high density lipoprotein cholesterol (non-HDL-C) were measured before angiography in all groups. Levels of serum TC, LDL-C and non-HDL-C of the II, III and IV group were significantly higher than those of the I group (4.78 +/- 0.82 mmol/L and 4.87 +/- 1.50 mmol/L and 4.73 +/- 0.99 mmol/L vs. 4.38 +/- 0.93 mmol/L, 2.91 +/- 0.68 mmol/L and 2.74 +/- 1.23 mmol/L and 2.64 +/- 0.84 mmol/L vs. 2.30 +/- 0.77 mmol/L, 3.58 +/- 0.75 mmol/L and 3.59 +/- 1.41 mmol/L and 3.43 +/- 0.94 mmol/L vs. 3.17 +/- 0.91 mmol/L; p < 0.05); the mean levels of TC, LDL-C and non-HDL-C associated positively with the Gensini score. CONCLUSION: Serum lipid levels correlate positively with the severity of coronary artery atherosclerosis in a Chinese population sample. Patients with higher levels of serum TC, LDL-C and non-HDL-C have more severe coronary atherosclerosis, compared with those with low levels of serum TC, LDL-C and non-HDL-C.     

软脉化斑汤对高血压合并动脉粥样硬化大鼠血管内皮细胞的保护作用及机制研究

目的研究软脉化斑汤对高血压合并动脉粥样硬化大鼠血管内皮细胞的保护作用及相关机制。方法选取8周龄雄性自发性高血压大鼠20只,随机分为模型组和软脉化斑汤组,每组10只。另选取8周龄WKY雄性大鼠10只作为对照组。检测不同时间点大鼠血压变化,苏木素-伊红(HE)染色分析血管组织病理形态;测定大鼠血清三酰甘油(TG)、总胆固醇(TC)、低密度脂蛋白胆固醇(LDL-C)、高密度脂蛋白胆固醇(HDL-C)水平,酶联免疫吸附试验(ELISA)法测定白介素-6(IL-6)、超敏C反应蛋白(hs-CRP)和肿瘤坏死因子-α(TNF-α)水平;同时测定超氧化物歧化酶(SOD)、丙二醛(MDA)、总抗氧化能力(T-AOC);免疫印迹法(Western Blot)测定血管内皮细胞血管细胞黏附分子-1(VCAM-1)及G蛋白信号调节因子16(RGS16)表达水平。结果干预4周、8周软脉化斑汤组大鼠血压低于模型组(P<0.05);与模型组比较,软脉化斑汤组大鼠TG、TC、LDL-C水平降低(P<0.05),HDL-C水平升高(P<0.05),IL-6、hs-CRP、TNF-α水平降低(P<0.05);与模型组比较,软脉化斑汤组大鼠SOD水平、T-AOC均升高(P<0.05),MDA水平下降(P<0.05);与模型组比较,软脉化斑汤组大鼠血管内皮细胞VCAM-1、RGS16水平下降(P<0.05)。结论软脉化斑汤可有效改善动脉粥样硬化大鼠血压及血脂代谢水平,保护血管内皮细胞损伤,其机制可能与抑制炎症反应、氧化应激及下调VCAM-1、RGS16蛋白表达有关。     

Plasma lipoprotein and apolipoprotein profile in alcoholic patients with and without liver disease: on the relative roles of alcohol and liver injury

In the present study, we report on alterations in plasma lipid, lipoprotein and apolipoprotein patterns in three separate populations of alcoholic patients, one without liver damage (Group I), a second presenting steatosis or mild alcoholic hepatitis or both (Group II) and a third with alcoholic cirrhosis (Group III), using a healthy, normolipidemic, nonalcoholic group as controls (Group C). Total plasma cholesterol levels were elevated in Groups II and III when compared with Groups I and C, while the ratio of esterified to free cholesterol was considerably lower in Group III than in the other groups. Plasma apo-AI levels were higher in Groups I and II than in Group C, but varied over a wide range in Group III. Apo-AII was present at higher concentrations in Groups I and II than in both Groups III and C. In contrast, no significant differences were detected in total apo-B levels, irrespective of the group. Modifications in the chemical composition of plasma lipoproteins primarily concerned a reduction in the cholesteryl ester content of low-density lipoproteins (LDL) and high-density lipoprotein (HDL) in Group III, this being compensated by a reciprocal increase in triglyceride. In addition, Group III lipoproteins, with the exception of HDL3 (density 1.100 to 1.140 gm per ml), exhibited a greater content of phospholipids than those of corresponding density from patients in Groups I and II. No significant differences were found in very low-density lipoprotein concentrations, while LDL levels increased in parallel with the severity of liver injury. In Groups I and II, HDL2 concentrations were elevated relative to Group C, while HDL3 decreased in parallel with the degree of impairment of liver function and thus from Group C to Group III.(ABSTRACT TRUNCATED AT 250 WORDS)     

The hypocholesterolemic effect of an antacid containing aluminum hydroxide.

STUDY OBJECTIVE: To evaluate the efficacy, safety, and hypocholesterolemic effect of an aluminum hydroxide-containing antacid in hypercholesterolemic individuals. DESIGN: A prospective, randomized, double-masked, placebo-controlled phase of 2 months' duration, followed by an open-design treatment phase of 2 months' duration and a washout phase of 2 months' duration. SETTING: Family practice clinics of two rural communities (kibbutzim) in Israel. PATIENTS: Fifty-six men and women with hypercholesterolemia (type IIa or IIb). Fifty individuals completed the study. INTERVENTION: After 2 months of dietary modification (low-fat, low-cholesterol diet), the participants were randomized into two matched groups. Group 1 (28 participants) was treated for 2 months with a chewable antacid tablet containing simethicone, magnesium hydroxide, and 113 mg of aluminum hydroxide per tablet, at a dose of two tablets four times daily. Group 2 (22 participants) was given a similar number of placebo tablets for 2 months. During the following 2 months, both groups received the antacid at the above dose. MEASUREMENTS AND MAIN RESULTS: Lipoprotein levels were evaluated at baseline and every 2 months thereafter for 6 months. Compared with pretreatment levels, Group 1 experienced a decrease in low-density lipoprotein cholesterol (LDL-C) of 9.8% after 2 months (p less than 0.001) and 18.5% after 4 months (p less than 0.001). Compared with Group 2, the decrease in LDL-C in Group 1 was 6.2% at the end of the 2-month double-masked, placebo phase. Although the high-density lipoprotein cholesterol (HDL-C) was also reduced in Group 1 at the end of 4 months of therapy (10.2%), the HDL-C/LDL-C ratio increased by 13% during the same interval (p less than 0.05). The treatment was well tolerated, with minimal side effects. CONCLUSIONS: An aluminum hydroxide-containing antacid reduces LDL-C in hypercholesterolemic individuals. Although HDL-C was also reduced to a lesser extent, the overall atherogenic index was improved. Further studies should be conducted to evaluate the long-term safety and efficacy of antacids containing aluminum hydroxide in hypercholesterolemic patients.     

老年冠心病患者血清脂质和脂质过氧化物测定的临床意义

本文观测了４４例老年冠心病患者血清脂质，丙二醛和超氧化物歧化酶，并与健康老年人对照比较，结果显示除胆固醇外其余各项指标２组间均有显著差异，老年ＣＨＤ组ＭＤＡ明显高于对照组，而ＳＯＤ则与之相反。多元回归分析表明，血清低密度脂蛋白胆固醇，而血清高密度脂蛋白胆固醇与ＳＯＤ呈显著正相关。提示老年ＣＨＤ患者高脂血症与脂质过氧化间有一定关系，它对判断老年ＣＨＤ的病情及预后有重要参考意义。     

Vitamin E does not slow the progression of hypercholesterolemic atherosclerosis

BACKGROUND:

Vitamin E suppresses the development of atherosclerosis but does not regress established hypercholesterolemic atherosclerosis.

OBJECTIVES:

To investigate whether vitamin E slows the progression of established atherosclerosis, and whether this effect is associated with reductions in serum lipids and oxidative stress.

METHODS:

The present study was performed in four groups of rabbits: group I, regular diet (control); group II, 0.25% cholesterol diet (two months); group III, 0.25% cholesterol diet (four months); and group IV, 0.25% cholesterol diet (two months) followed by 0.25% cholesterol and vitamin E (two months). Serum lipids and the chemiluminescent activity of white blood cells (WBC-CL), a measure of oxygen radical production by white blood cells, were measured before and at monthly intervals for the duration of the study. Aortas were removed at the end of the protocol for assessment of atherosclerosis and the chemiluminescent activity of aortic tissue (aortic-CL), a measure of antioxidant reserve.

RESULTS:

Atherosclerosis was associated with hyperlipidemia and increased oxidative stress, indicated by increased nonactivated WBC-CL and alteration of the aortic-CL. Significant areas of the intimal surfaces of the aortas from group II (26.54%±4.11%), group III (69.37%±5.34%) and group IV (65.96%±7.86%) were covered with atherosclerotic lesions. Vitamin E did not alter serum lipids, aortic antioxidant reserve or WBC-CL. Vitamin E was ineffective in slowing the progression of hypercholesterolemic atherosclerosis.

CONCLUSION:

Vitamin E did not slow the progression of hypercholesterolemic atherosclerosis, and this effect was associated with its ineffectiveness in reducing serum lipids and oxidative stress.     

Association of plasma triglyceride-rich lipoprotein remnants with coronary atherosclerosis in cases of sudden cardiac death

Among the risk factors for coronary atherosclerosis, elevated LDL-C level is best known. The action of lipoprotein lipase on triglyceride-rich lipoproteins produces remnant lipoprotein particles enriched in cholesterol and apolipoprotein E (apo E). Apo E serves as the ligand for uptake of remnant lipoproteins via the LDL-receptor or the remnant receptor. In this study, postmortem plasma total cholesterol, triglycerides (TG), VLDL-C, HDL-C, lipoprotein (a) [Lp(a)] and remnant-like lipoprotein particles (RLP)-cholesterol, RLP-TG, apolipoproteins B, C III and E were measured, together with LDL-C to assess their potential contribution to the severity of coronary and aortic atherosclerosis of the 197 cases of sudden death (132 cardiac death and 65 non-cardiac death). In all cases, the severity of coronary atherosclerosis was determined at postmortem pathological examination. RLP-cholesterol (RLP-C) and LDL-C concentrations were significantly higher in cases with advanced coronary atherosclerosis compared with those without coronary atherosclerosis; respective median values were 13.5 vs 8.4 mg/dl (P < 0.001) and 140 vs 115 mg/dl (P < 0.05). RLP-C levels were more strongly correlated with the severity score of coronary atherosclerosis than LDL-C.     

Rapamune Does Not Attenuate High Cholesterol-Induced Atherosclerosis in Rabbits

Solid-organ transplant recipients are prone to develop atherosclerosis. The objectives of this study were to investigate the effects of Rapamune (Wyeth Canada, Saint-Larent, QC, Canada) on the rabbit model of atherosclerosis. The rabbits were assigned to four groups: group I, regular diet (control); group II, 1% cholesterol diet; group III, control with Rapamune (1 mg/kg/d orally); and group IV, high cholesterol diet with Rapamune. Blood samples for serum lipids (triglycerides [TG], total cholesterol [TC], low-density lipoprotein cholesterol [LDL-C], high-density lipoprotein cholesterol [HDL-C]), as well as malondialdehyde, and protein carbonyls, the indices of oxidative stress were collected at the end of 2 months on the respective diet regimen. Aortic tissue for atherosclerotic changes were also collected for oxidative stress indices were also collected. Rapamune reduced serum levels of TG, TC, LDL-C, and HDL-C. Rapamune elevated the oxidative stress in rabbits on high cholesterol diet. Rapamune did not attenuate extent of atherosclerosis (group II vs. group IV, 45.00 ± 12.00 vs. 57.28 ± 2.99%); intimal thickness (group II vs. group IV, 32.38 ± 7.14 × 10³ vs. 21.90 ± 11.98 × 10³ μm²); intimal/medial ratio (group II vs. group IV, 0.50 ± 0.06 vs. 0.35 ± 0.06); and macrophage accumulation (group II vs. group IV, 69.72 ± 5.02 vs. 61.52 ± 8.94%) in the intima of rabbits on high cholesterol diet. The data suggest that (1) Rapamune increased the oxidative stress in rabbits on high cholesterol diet and (2) Rapamune did not attenuate the hypercholesterolemic atherosclerosis in the rabbit model.