Oxidized lipoproteins in blood plasma: possible marker of atherosclerosis progression

Oxidized lipoproteins and antioxidants were detected during the course of hypercholesterolemia development in cholesterol-fed rabbits. Lipid peroxides in blood plasma and very-low-, low-, and high-density lipoproteins (beta-VLDL, LDL, and HDL) were increased during the course of hypercholesterolemia. The content of phospholipid peroxides increased in beta-VLDL and LDL in parallel to that of cholesterol, whereas the amount of alpha-tocopherol was decreased either in lipoproteins or blood plasma. Ascorbate and urate concentrations were also decreased. Lipid peroxides were positively correlated with volume and area of atherosclerotic lesions, suggesting a relation between the concentrations of lipid peroxides in blood plasma and the progression of atheromatous lesions.     

The study of cytokine content and ganglioside metabolism in experimental brain edema

A blood cytokine profile and also the brain content of lipid peroxidation (LPO) products and gangliosides were investigated in rats with experimental brain edema. The development of brain edema was accompanied by the increase in pro-inflammatory and a decrease in anti-inflammatory cytokine content. In parallel, accumulation of LPO products (conjugated dienes, hydroperoxides, and malondialdehyde) was observed. The study of ganglioside content under conditions of experimental brain edema revealed a decrease of their hydrolytic degradation product, sphingosine.     

Anti-oxidant effects of cinnamon (Cinnamomum verum) bark and greater cardamom (Amomum subulatum) seeds in rats fed high fat diet

In order to gain insight into the antioxidant effect of cinnamon (Cinnamomum verum; Lauraceae) and cardamom (Amomum subulatum; Zingiberaceae) hepatic and cardiac antioxidant enzymes, glutathione (GSH) content and lipid conjugated dienes were studied in rats fed high fat diet along with cinnamon or cardamom. The antioxidant enzyme activities were found to be significantly enhanced whereas GSH content was markedly restored in rats fed a fat diet with spices. In addition, these spices partially counteracted increase in lipid conjugated dienes and hydroperoxides, the primary products of lipid peroxidation. Thus, it appears that these spices exert antioxidant protection through their ability to activate the antioxidant enzymes.     

Effect of diltiazem on cholesterol and phospholipid content and intensity of free radical oxidation process in plasma membranes of cardiomyocytes and blood cells in experimental hypercholesterolemia

Changes of lipid structure and function in membranes of cardiomyocytes and blood cells of rabbits were investigated under the effect of experimental hypercholesterolemia and calcium antagonist diltiazem influence. The activity of peroxide oxidizing of lipids (POL) and protein in membrane of sarcolemma, blood cells and serum, and activity of the same enzymes of antioxidant system--catalase (CAT) and superoxide dismutase (SOD) were studied as well. The research marks that diltiazem was manifested by activation of antioxidant system in cardiomyocytes and membrane sarcolemma, normalization of its lipid structure and by the decrease of the content of products POL and oxidizing of protein.     

The effect of changes in the lipid composition of membranes on the functional activity of platelets

The phospholipid and fatty acid composition as well as the effect of platelet lipid composition modifications on the functional parameters of platelets were studied in blood sera from healthy donors and from patients with ischemic heart disease (IHD). It was found that the content of cholesterol and phospholipid hydrolysis products in IHD patients was increased. Reconstitution of the lipid composition of donor platelets by lysophosphatidylcholines, phosphatidic acid, fatty acids and cholesterol led to the increase of the platelet functional activity. It is suggested that the increased adsorption of Ca2+ on platelet surface is due to alterations in the platelet lipid composition in IHD and after modifications.     

Thermal recovery after passage of the pulmonary circulation assessed by deconvolution

We determined the effect of H2O2 on both the physiological and biochemical lung changes seen in the adult sheep after endotoxin. Fourteen unanesthetized adult sheep with chronic lung lymph fistula were given Escherichia coli endotoxin (1 microgram/kg) over 30 min. Seven sheep were given catalase (32,500 U/kg body wt) as an intravenous bolus 30 min before endotoxin. Four sheep were given catalase alone. Oxidant lung changes were measured using arterial plasma conjugated dienes and lung tissue malondialdehyde (MDA) content, both reflecting the lipid peroxidation process. Animals were killed 5 h after endotoxin. We found that endotoxin alone caused an early increase in pulmonary arterial pressure lung lymph flow (QL), plasma thromboxane B2, 6-keto-prostaglandin F1 alpha, and plasma conjugated dienes. A decrease in cardiac output and arterial PO2 was also seen. A three- to four-fold increase in protein-rich QL was noted at 3-4 h as well as a continued increase in arterial conjugated dienes. Lung MDA and water content were also significantly increased from base line. Catalase pretreatment significantly attenuated both the physiological changes and the prostanoid and conjugated diene release. Lung MDA and water content also remained at base line. We conclude that H2O2 plays a major role in endotoxin-induced lung injury as well as the resulting lipid peroxidation process.     

High-density lipoprotein inhibits the oxidative modification of low-density lipoprotein

Oxidatively modified low-density lipoprotein (LDL), generated as a result of incubation of LDL with specific cells (e.g., endothelial cells, EC) or redox metals like copper, has been suggested to be an atherogenic form of LDL. Epidemiological evidence suggests that higher concentrations of plasma high-density lipoprotein (HDL) are protective against the disease. The effect of HDL on the generation of the oxidatively modified LDL is described in the current study. Incubation of HDL with endothelial cells, or with copper, produced much lower amounts of thiobarbituric acid-reactive products (TBARS) as compared to incubations that contained LDL at equal protein concentrations. Such incubations also did not result in an enhanced degradation of the incubated HDL by macrophages in contrast to similarly incubated LDL. On the other hand, inclusion of HDL in the incubations that contained labeled LDL had a profound inhibitory effect on the subsequent degradation of the incubated LDL by the macrophages while having no effect on the generation of TBARS or the formation of conjugated dienes. This inhibition was not due to the modification of HDL as suggested by the following findings. (A) There was no enhanced macrophage degradation of the HDL incubated with EC or copper alone, together with LDL, despite an increased generation of TBARS. (B) HDL with the lysine groups blocked (acetyl HDL, malondialdehyde (MDA) HDL) was still able to prevent the modification of LDL and (C) acetyl HDL and MDA-HDL competed poorly for the degradation of oxidatively modified LDL. It is suggested that HDL may play a protective role in atherogenesis by preventing the generation of an oxidatively modified LDL. The mechanism of action of HDL may involve exchange of lipid peroxidation products between the lipoproteins.     

Effect of bacterial lipopolysaccharide on the content of lipid peroxidation products in lungs and other organs of mice

The influence of lipopolysaccharide fromEscherichia coli (LPS, 17 mg/kg body weight) on the lipid peroxidation process in organs of mice was studied. The content of conjugated dienes (CD), lipid peroxides (LP), malondialdehyde (MDA) (all three lipid peroxidation by-products), peroxidase (PO) activity and wet-to-dry weight ratio in lungs, heart, spleen, kidneys and liver were determined 1.5 h after intravenous injection of LPS. Animals observed at this time-point had reduced activity and decreased body temperature by about 2°C, however, all analysed organs did not reveal any changes of wet-to-dry weight ratio comparing to organs from mice injected with sterile, pyrogen free 0,9% NaCl. Only extracts from heart and lungs showed significant increase in the tissue level of at least two lipid peroxidation products. The heart content of CD, MDA, and LP was about 1.5-, 1.3-, and 2.4-fold higher than in control group. In lungs CD and MDA increased 3.3- and 1.3-times but in spleen only content of LP was elevated. In these organs the suppression of PO activity was also observed. Liver and kidneys did not reveal any convincing enhancement of lipid peroxidation process and alterations of PO activity. Since free radical reactions are involved in lipid peroxidation process and inactivation of PO these results suggest that heart, lungs and spleen are the organs mostly exposed to oxidative stress during the first 1.5 h after single injection of LPS in mice.Abbreviations CD conjugated dienes - LP lipid peroxides - LPS lipopolysaccharide - MDA malondialdehyde - PMNL polymorphonuclear leukocytes - PO peroxidase - TBA thiobarbituric acid     

Endotoxemia produces an increase in arterial but not venous lipid peroxides in sheep

Our purpose was to determine the effect of an endotoxin-induced lung injury on circulating lipid peroxides. We measured both malondialdehyde (MDA) and conjugated dienes (as optical density at 233 nm) in aortic and venous plasma and lung lymph in 10 unanesthetized sheep given 1 microgram/kg of Escherichia coli endotoxin. Total lipids and prostanoids 6-ketoprostaglandin F1 alpha and thromboxane B2 were also measured. Six control sheep were also studied. Animals were monitored for a 12-h period and then killed, and lung tissue MDA was determined. A two-phase endotoxin response was noted with an initial pulmonary hypertension followed by a steady-state increase in protein-rich lung lymph flow (QL) between a 3- and 6-h period. Aortic plasma MDA was significantly increased from a base line of 4.8 +/- 1.4 to 8.9 +/- 1.6 and 7.5 +/- 1.3 nmol/ml at 1 and 4 h post-endotoxin. Aortic plasma conjugated dienes increased in all 10 sheep post-endotoxin. Venous levels of both MDA and conjugated dienes were not significantly increased. Lung QL increased two- to three-fold. Lung lymph MDA increased significantly at 1 h post-endotoxin. Lymph conjugated dienes decreased. Plasma and lymph lipid peroxide levels returned to base line by 12 h in most animals. However, tissue MDA remained significantly increased in all sheep from base line of 45 +/- 9 to 85 +/- 14 nmol/g tissue. We conclude that both MDA and conjugated dienes are transiently released into aortic plasma during endotoxin-induced oxidant lung injury.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of melatonin on free radical homeostasis in rat tissues at thyrotoxicosis

Experimental thyrotoxicosis in rats is accompanied by the increase of serum alanine aminotransferase (AlAT), aspartate aminotransferase (AsAT), creatine phosphokinase-MB (CPK-MB) activities and the content of primary products of lipid peroxidation, conjugated dienes, in liver, heart and blood. This suggests impairments in functioning of these organs, which accompany intensification of free radical processes. Melatonin administration resulted in the decrease of AlAT, AsAT, CPK-MB and conjugated dienes; this indicates positive effect of melatonin in this pathology. Thyrotoxicosis is accompanied by the increase of catalase activity in rat liver, heart and serum. Exogenous melatonin decreased specific activity of serum and heart catalase by 22 and 43%, respectively, compared with rats subjected to hyperthyroidism. However, there was insignificant increase in specific activity of liver catalase (by ～15%). Melatonin administration caused a decrease of α-tocopherol content increased in rat tissues under conditions of hyperthyroidism. Thus, exogenous melatonin is capable to reduce intensity of lipid peroxidation in hyperthyroidism and to act as an adaptogen, regulating free radical homeostasis in response to action of pathogenic factors on organism that is associated by concomitant reduction of mobilization of components of the antioxidant system.     

Increased myeloperoxidase activity is a risk factor for ischemic heart disease in patients with diabetes mellitus

Using a previously developed spectrophotometric method (Bioorg. Khim. 2009, vol. 35, pp. 629–639) a significant increase of myeloperoxidase (MPO) activity (versus healthy control) was found in blood plasma of patients with type 2 diabetes mellitus (DM2) without cardiovascular complications, and also in patients with ischemic heart disease (IHD). The plasma MPO concentration measured by an enzyme-linked immunosorbent assay was significantly higher only in blood plasma of patients with DM2 and IHD. A significant positive correlation between blood MPO activity and blood MPO content was observed only in blood plasma samples from healthy donors. Increased MPO activity did not correlate with MPO concentration in blood plasma of patients with DM2 and DM2 with IHD. Taken together, these results indicate that studies on the MPO role in the development of pathological processes should include simultaneous determination of both the amount of enzyme and its peroxidase activity in blood of patients. The proposed approach gives comprehensive information about the relationship between MPO activity and MPO concentration in patient’s blood. Since the high concentration of MPO is a diagnostically important parameter for the prediction of development of endothelial dysfunction and cardiovascular diseases, the obtained results point to the contribution of MPO-dependent reactions in cardiovascular complications associated with diabetes mellitus. MPO activity may serve as an additional diagnostic criterion for determination of risk of IHD in DM patients.     

The lipid peroxidation system in the retina and brain of rats during early postnatal ontogeny

The content of the lipid peroxidation products in the rat retina and brain tissues during the early postnatal period (20-45 day of life) was estimated. It was shown during this period the content of conjugated dienes was decreased: the content of malondialdehyde and Schiff bases was without changes in the rat retina. At the same time the content of the conjugated dienes and Schiff bases in the brain tissue was proportionally increased. The activity of glutathioneperoxidase and glutathionereductase was decreased in the retina and not changed in brain. In the same period of the life the content of alpha-tocopherol in the retina was increased. We observed also the enhance of the rate of the induced lipid peroxidation in brain and retina of older animals.     

D-galactosamine induced hepatitis in the rabbit: effect on lecithin:cholesterol acyltransferase activity, plasma lipid transfer protein activity and high density lipoproteins

Hepatitis was induced in rabbits by a single intraperitoneal injection of D(+)-galactosamine-HCl (750 mg/kg body wt). Plasma lecithin:cholesterol acyltransferase activity fell to 5% and lipid transfer protein activity to 50% of control values 48 hr after injection. Discoid high density lipoprotein began to appear in plasma of treated rabbits 36 hr after injection, along with populations of high density lipoprotein (HDL) which were both smaller (radius 3.7 nm) and larger (radius 5.9 nm) than the original HDL population (radius 4.8 nm).     

Ultraviolet-treated lipoproteins as a model system for the study of the biological effects of lipid peroxides on cultured cell. I. Chemical modifications of ultraviolet-treated low-density lipoproteins

A new experimental model system constituted by ultraviolet-treated low-density lipoproteins (LDL) has been designed in order to investigate the biological effects of lipid peroxides entering the cell through the endocytotic pathway. This paper reports the chemical modifications of the lipid components and apolipoproteins of the ultraviolet-treated LDL. Human LDL were submitted to short ultraviolet radiations (254 nm, 0.5 mW/cm2, for variable periods of time) and compared to LDL peroxidized by iron. The lipid peroxidation was monitored by following the formation of the peroxidation products (conjugated dienes, thiobarbituric acid-reactive substances (TBARS) and fluorescent lipid-soluble products) and the change of the composition in polyunsaturated fatty acids, carotenes and vitamin E. Several parameters of the apo B-100 structure were investigated: molecular size (by SDS-PAGE) and TNBS-reactive amino groups (chemical determination by trinitrobenzene sulfonic acid). The most important feature was the absence of major modification of apo B-100 in ultraviolet-treated LDL: the molecular weight and the content in TNBS-reactive amino groups of apo B-100 were not modified. In contrast, iron-treated LDL exhibited a loss of the apo B-100 band and a decrease in the number of TNBS-reactive amino group. Both ultraviolet radiations and iron ions induced a significant decrease in the content of polyunsaturated fatty acids, carotenes and vitamin E together with a large formation of lipid peroxidation products. However, the time-course of the formation of conjugated dienes, TBARS and fluorescent lipid-soluble products was quite different using the two oxidative systems. These results demonstrate that ultraviolet radiations induced a strong peroxidation of the lipid content of LDL and no (or only minor) changes in the apolipoprotein moiety whereas iron-catalyzed peroxidation resulted in the formation fo lipid peroxidation products as well as apo B alterations.     

莲房原花青素对家兔血脂及肝组织形态的影响

目的：观察莲房原花青素（LSPC）对实验性高血脂兔及其肝组织形态学的影响。方法：按血胆固醇水平将实验性高血脂兔随机分组：空白对照组,三个不同LSPC剂量（100,200,400mg/kg）组,测定口服LPSC前后血清和肝总胆固醇（TC）、甘油三酯（TG）、血清低密度脂蛋白－胆固醇（LDL－C）、高密度脂蛋白－胆固醇（HDL－C）等指标,并对家兔肝脏进行病理学检查。结果：低剂量LSPC能明显降低高血脂兔的血清及肝脏中TG（P＜0．05）,显著升高血清HDL－C值（P＜0．01）;高剂量LSPC能显著减少高血脂兔血清TC、LD1－C（P＜0．01）,同时升高血清HDL－C值（P＜0．05）,但对肝组织形态有一定的副作用。结论：结论：提示莲房原花青素可能具有调节血脂的作用。     

Cholesterol-rich diets have different effects on lipid peroxidation, cholesterol oxides, and antioxidant enzymes in rats and rabbits

The objective of this study was to compare the effect of cholesterol feeding of rats and rabbits. The levels of lipid peroxidation products and oxysterols in the plasma of the two species plus the antioxidant enzyme activities in the liver and erythrocytes were measured to explain their different susceptibilities to atherosclerosis. Our study showed that rats are less susceptible than are rabbits to the atherogenic effect of a cholesterol-rich diet because of differences in lipid peroxidation products as well as antioxidant enzymes activities in their livers. In rabbits, cholesterol feeding produced severe hypercholesterolemia (43-fold increase) and increased plasma and liver lipid peroxidation. Total as well as the individual oxysterol contents of 7alpha-, 7beta-hydroxycholesterol, alpha-epoxy, beta-epoxycholesterol, cholestanetriol, 7-keto, and 27-hydroxycholesterol significantly increased in the plasma of hypercholesterolemic (HC) rabbits. Erythrocyte glutathione peroxidase (GSH-Px) activity significantly decreased whereas catalase activity significantly increased in HC rabbits. In rats cholesterol feeding increased the plasma cholesterol only twofold and had no effect on plasma or liver lipid peroxidation. Only 7alpha- and 7beta-hydroxycholesterol increased and no change was observed in any of the antioxidant enzymes activity in the erythrocytes. Although cholesterol feeding caused a 10-fold increase of liver cholesterol as ester in both rats and rabbits, the antioxidant enzyme GSH-Px and catalase activities in the liver significantly increased in rats but significantly decreased in rabbits. The increase of GSH-Px and catalase activities in the liver of cholesterol fed rats could have a protective role against oxidation, thus preventing the formation of lipid peroxidation and oxysterols.     

Phospholipid composition of erythrocyte membrane under conditions of postmyocardial infarction cardiosclerosis

Changes in phospholipid composition of the erythrocyte membranes have been studied in experimental postmyocardial infarction cardiosclerosis. Erythrocyte membranes from animals with cardiosclerosis formed after experimental occlusions of coronary arteries were characterized by significant decrease of a minor phospholipid, phosphatydylinositol (by more than 40%) and the increase of the major phospholipid, phosphatydylethanolamine (by 20%). There was high content of lipid peroxidation products, malondialdehyde and conjugated dienes and the decrease in the activity of antioxidant enzymes, catalase and superoxide dismutase in blood serum of these animals. We have concluded the formation of postmyocardial infarction cardiosclerosis is accompanied by the increase of free radical reactions. This causes changes in phospholipid composition of cell membranes and the decrease of compensatory capacities of the enzymatic antioxidant system. These changes form a metabolic background, which can influence cardiac remodeling properties.     

Activation of lipid peroxidation processes in chronic ischemic heart disease

The content of lipid peroxidation products--hydroperoxides with conjugated double bonds and fluorescent compounds, which are formed on interaction of primary lipid peroxidation products and proteins, considerably increases in blood plasma of patients suffering from coronary heart disease. Treatment with combined vitamins E and C enables the blood plasma lipid peroxidation products to be decreased to a far greater extent as compared with conventional therapy.     

Activation of lipid peroxidation and changes in vitamin E contents in the lungs under oxidative stress]

The lipid peroxidation (LPO) of the lung tissue and the bronchoalveolar lavage in rats under the influence of immobilization has been investigated. The effects accompanying the development of oxidative stress in animals--an increase in the content of conjugated dienes and fluorescent LPO products in biological objects and a strong decrease in the content of vitamin E in the lung tissue were registered.     

Lipid peroxidation and antielastase activity in the lung under oxidant stress: role of antioxidant defenses

The role of lipid peroxidation in the inactivation of alpha 1-protease inhibitor (alpha 1-PI) in the alveolar lining fluid of human subjects has been examined under oxidant stress. Exposure to nitrogen dioxide (NO2) at 4 ppm for 3 h resulted in a significant increase in the amount of lipid peroxidation products in the alveolar lining fluid, with conjugated dienes the predominant species. Four-week supplementation with vitamins C and E before NO2 exposure markedly decreased the levels of conjugated dienes (control 804 +/- 103 pmol/micrograms total phospholipids vs. vitamin-supplemented 369 +/- 58, P = 0.003). Malondialdehydes, although detectable in the lavage fluid, contributed little to the total amount of lipid peroxidation products, and the levels were comparable in both groups. NO2 exposure in the absence of vitamin supplementation caused a significant decrease in the elastase inhibitory capacity (EIC) of the alveolar lining fluid in the control group but not in the vitamin-supplemented group [control 3.67 +/- 0.32 micrograms alpha 1-PI/micrograms porcine pancreatic elastase (PPE) vs. vitamin-supplemented 2.75 +/- 0.17, P less than 0.03]. The vitamin-supplemented group had a lower level of conjugated dienes and a higher EIC. Conversely, the control group had higher levels of conjugated dienes and a lower EIC in their lavage fluid. These studies demonstrate that lipid peroxidation occurs as an early event during oxidant exposure in the lungs of normal subjects. The appearance of lipid peroxidation products in the lavage fluid is associated with a decrease in the EIC of the alveolar lining fluid. Vitamins C and E diminish lipid peroxidation and preserve the EIC of the lower respiratory tract fluid during oxidant stress.