Blood Plasma Lipoproteids: Oxidizability and Participation in the Transport of Acylhydroperoxy-Derivatives of Phospholipids.

Oxidatively modified plasma lipoproteins play an important role in the molecular mechanisms of vascular wall damage in atherosclerosis and diabetes mellitus. It was found that the oxidizability of low-density lipoproteins (LDLs) is more than one order of magnitude higher than that of high-density lipoproteins (HDLs). It was shown that acylhydroperoxy derivatives of phospholipids of oxidized biomembranes are predominantly captured by LDL particles, but not by HDLs, which refutes the hypothesis about the involvement of HDLs in the reverse transport of lipohydroperoxides (LOOH). The results suggest the possibility of different mechanisms of LOOH accumulation in LDLs: due to the increased oxidizability of LDLs and due to the effective transmembrane transport of LOOH by LDL particles.

[Telomere length as a biomarker of the risk of cardiovascular complications in patients with coronary heart disease].

AIM: To study the effect of oxidative stress and telomere length in the chromosomes of blood leukocytes in patients with coronary heart disease (CHD) on the development of cardiovascular complications. MATERIALS AND METHODS: In 119 patients with CHD, the level of oxidatively modified low-density lipoproteins (ox-LDL) in blood plasma and the length of telomeres in nuclear blood cells were determined during the examination. After 5 years, a telephone survey of patients (or their relatives) was conducted to obtain data on the presence of cardiovascular complications. Telomere length was determined using quantitative real-time PCR, and the level of ox-LDL was determined by immunochemical method. RESULTS: It was found that reducing the length of telomeres in patients with CHD increases the risk of subsequent development of cardiovascular complications. A strong negative correlation was found between the level of ox-LDL and telomere length in the group of examined CHD patients who had cardiovascular complications after 5 years. CONCLUSION: CHD patients with short telomere length and high levels of ox-LDL have an increased risk of cardiovascular complications during 5 years.

[Impact of summer heat waves on key parameters of oxidative stress in patients with coronary artery disease].

AIM: To assess the impact of summer heat waves on key parameters of oxidative stress in patients with coronary heart disease. MATERIALS AND METHODS: We included 30 male patients aged 5213 years with stable angina pectoris of IIIII functional class with at least one coronary artery stenosis proved by angiography (ischemic group) in comparison with 10 male patients aged 487 years with no angiographic sings of significant coronary stenosis and without angina manifestation (non-ischemic group). The following parameters were studied: activity of superoxide dismutase (Cu,Zn-SOD), catalase (CAT), glutathione peroxidase (GSH-Px), the level of malondialdehyde (MDA) and MDA-modified low-density lipoproteins (MDA-LDL). The analysis of indicators was performed at normal average daily temperature (daytime temperature not higher than 20С) and after a heat wave (daytime temperature above 27C for more than 2 consecutive days). RESULTS: Our study revealed the decrease of CAT and GSH-Px activities with increased activity of Cu,Zn-SOD in both groups after the heat wave. At the same time we observed accumulation of MDA and increased MDA-LDL level in both groups. Initially ischemic patients showed significantly increased level of CAT and GSH-Px activity compared to the non-ischemic group, while it was no difference in activity of Cu,Zn-SOD and MDA and MDA-LDL level. We observed significant reduce of Cu,Zn-SOD activity in ischemic patients compared to non-ischemic group with no significant differences in all other studied parameters of oxidative stress after heat wave. CONCLUSION: Changes in the key parameters of oxidative stress in patients with ischemic heart disease during summer heat waves are comparable to those in patients without ischemia, however significantly greater inhibition of GSH-Px activity and significantly lower increase in Cu,Zn-SOD activity was noted. These results may indicate misregulation of free radical processes in patients with ischemic heart decease.

[Elimination kinetics of carbonyl-modified low density lipoproteins from bloodstream]. / Kinetika éliminirovaniia karbonil-modifitsirovannykh lipoproteinov nizkoi plotnosti iz krovotoka.

The elimination kinetics of carbonyl-modified low density lipoproteins (LDL) from rabbit bloodstream was studied using isolated LDL of rabbits and humans after preliminary biotinylation or labeling with FITZ. LDL from rabbit or human blood plasma were isolated using differential ultracentrifugation in a density gradient, and then LDL were labeled using biotinylation or FITZ, after which they were modified with various low molecular weight natural dicarbonyls: malondialdehyde (MDA), glyoxal or methylglyoxal. Native and dicarbonyl-modified biotinylated or FITZ-labeled LDL were injected into the ear vein of rabbits and blood samples were taken at certain intervals. To determine the content of biotinylated LDL in blood plasma, an enzyme immunoassay was performed; FITZ-labeled LDL were determined by spectra fluorescence. It is shown that glyoxal- and methylglyoxal-modified LDL in rabbits and humans circulated in the bloodstream for almost the same time as native (unmodified) LDL. At the same time, MDA-modified rabbit and human LDL were extremely quickly eliminated from the rabbit bloodstream. Dicarbonyl-modified LDL from the donors blood plasma were not associated with the red blood cells and endothelial cells. It has been shown that using the kits Oxidized LDL ELISA ("Mercodia", Sweden), it is possible to identify mainly MDA-modified LDL. The level of MDA-modified LDL in the blood plasma of CHD patients sharply decreases during therapy with the hypocholesterolemic drug the PCSK9 inhibitor (evulokumab), which activates LDL reutilization in the liver cells. These results explain the extreme drop in the level of MDA-modified LDL by their increased utilization in hepatocytes. The results obtained indicate a high atherogenicity of glyoxal- and methylglyoxal-modified LDL, long-term circulating in the bloodstream.

[Indicator Characterizing Carbonyl-Dependent Modification of Erythrocytic Superoxydismutase as a Biochemical Marker of Oxidative Stress in Coronary Heart Disease].

Aim To study the oxidative modification of red blood cell Cu,Zn superoxide dismutase (SOD) in patients with ischemic heart disease (IHD) in vivo and in vitro to substantiate the use of a new oxidative stress marker.Material and methods Red blood cell Cu,Zn SOD was measured by depression of nitrotetrazolium blue reduction by the superoxide anion generated in xanthine oxidase xanthine oxidation. Red blood cell Cu,Zn SOD was measured immunochemically. The biochemical study was performed in the control group (patients with low extremity fracture without known history of cardiovascular diseases and hyperlipidemia) and in groups of patients with acute myocardial infarction, stable angina, and decompensated heart failure. For evaluation of oxidative stress intensity in IHD patients, an empirical SOD oxidative modification coefficient (OMCSOD) was proposed, which is a Cu,Zn SOD activity / Cu,Zn SOD content ratio.Results The red blood cell Cu,Zn SOD activity was significantly decreased in all IHD groups compared to the control group. Furthermore, OMCSOD was also considerably decreased in IHD patients, which warrants the use of this biochemical index as an oxidative stress marker.Conclusion It was shown that the Cu,Zn SOD modification was induced by interaction of the enzyme molecules with a natural dicarbonyl, malonic dialdehyde, and OMCSOD can be used for evaluation of oxidative stress intensity in IHD patients.

Natural Dicarbonyls Inhibit Peroxidase Activity of Peroxiredoxins.

It was established that recombinant human peroxiredoxins (Prx1, Prx2, Prx4, and Prx6) inhibit natural dicarbonyls formed during free radical peroxidation of unsaturated lipids (malonic dialdehyde) and oxidative transformations of glucose (glyoxal and methylglyoxal). A possible role of the decrease in the activity of peroxiredoxins under oxidative and carbonyl stress is discussed as an important factor that triggers the molecular mechanisms of vascular wall damage in atherosclerosis and diabetes mellitus.

PCSK9 Inhibitor causes a decrease in the level of oxidatively modified low-density lipoproteins in patients with coronary artery diseases.

AIM: We study the dynamics of oxidatively modified low-density lipoprotein (ox-LDL) content in blood plasma, as well as changes in the activity of key antioxidant enzymes such as Se-containing glutathione peroxidase (GSH-Px) Cu,Zn-superoxide dismutase (SOD) and catalase in erythrocytes of patients with coronary artery disease during treatment with PCSK9 inhibitor (ewolocumab). MATERIALS AND METHODS: The study included 9 men (59 ± 10 years) with coronary artery disease with atherosclerotic lesion at least one main coronary artery according to coronary angiography. Patients took standard therapy before taking the study, everyone took the maximum tolerated dose of statins. Since the target cholesterol levels of low-density lipoprotein cholesterol (LDL-C) were not achieved during the statin therapy, patients were prescribed lipid-lowering therapy with the inclusion of the inhibitor PCSK9-emocoucumab from Amgen 420 mg once a month. The content of lipid metabolism indices was determined by standard biochemical methods. The level of ox-LDL in the blood plasma was determined by the immunochemical method. The activity of antioxidant enzymes was determined in blood erythrocytes using biochemical techniques. RESULTS: Cholesterol-lowering drug of the new type - inhibitor protein convertase subtilisin/kexin type 9 (PCSK9) evolocumab (Amgen) not only effectively lowers the level of cholesterol in low density lipoprotein (LDL), but also significantly reduces the content of oxdatively modified LDL in blood plasma. Unlike statins, the inhibitor of PCSK9 does not cause a decrease in the activity of antioxidant enzymes of the blood. CONCLUSION: PCSK9 inhibitor has no effect on the parameters of oxidative stress.

Oxidative and carbonyl stress as a factors of the modification of proteins and DNA destruction in diabetes.

AIM: To study the oxidative damage of biopolymers (proteins and nucleic acids) in blood of patients with type 2 diabetes mellitus (DM). MATERIALS AND METHODS: In the blood of 50 patients with DM and 25 patients without disorders of carbohydrate metabolism were estimated: the level of oxidized low-density lipoprotein (oxLDL) by immunochemical method, the content of SH-groups in plasma proteins, the activity of Cu, Zn-superoxide dismutase (SOD) in erythrocytes, the length of telomere in leukocyte DNA, the level of 8-hydroxy-2'-deoxygunosine (8-oxo-dG) in plasma and urine. RESULTS: It is shown that in DM patients the level of oxLDL increases and the content of SH-groups in proteins and peptides of the blood plasma decreases, which indicates the development of oxidative stress. In addition, a carbonyl-dependent modification of erythrocyte SOD was detected in DM patients, as well as oxidative DNA destruction (decrease in telomere length in leukocytes and an increase in the level of 8-oxo-dG in blood plasma and urine). CONCLUSION: On the basis of the definition of a complex of correct indicators, a multiple oxidative modification of biopolymers of blood (proteins and DNA) was detected in patients with DM.

Influence of dicarbonyls on kinetic characteristics of glutathione peroxidase.

Se-containing glutathione peroxidase (GSH-Px) is one of the key enzymes of the body's antioxidant system. The kinetic characteristics of GSH-Px (substrate is tert-butyl hydroperoxide) after modification of the enzyme by various concentrations of natural dicarbonyls (glyoxal, methylglyoxal, malonic dialdehyde) were studied. It was shown that dicarbonyls affected both K m and V max for GSH-Px. It is suggested that the effect of various dicarbonyls on GSH-Px depends on the molecular mechanisms of their interaction with the amino acid residues of the enzyme.

Methylglyoxal as a scavenger for superoxide anion-radical.

Methylglyoxal at a concentration of 5 mM caused a significant inhibition of superoxide anion radical (O2 (·-)) comparable to the effect of Tirone. In the process of O2 (·-) generation in the system of egg phosphatidylcholine liposome peroxidation induced by the azo-initiator AIBN, a marked inhibition of chemiluminescence in the presence of 100 mM methylglyoxal was found. At the same time, methylglyoxal did not inhibit free radical peroxidation of low-density lipoprotein particles, which indicates the absence of interaction with methylglyoxal alkoxyl and peroxyl polyenoic lipid radicals. These findings deepen information about the role of methylglyoxal in the regulation of free radical processes.

Enzymatic antioxidant system of endotheliocytes.

It is shown that endothelial cells from human umbilical vein have a reduced activity and gene expression of the "classic" antioxidant enzymes (Cu,Zn-superoxide dismutase, catalase, and Se-containing glutathione peroxidase). At the same time, a high expression level of peroxiredoxin genes was identified in the same endothelial cells, which obviously indicates the predominant involvement of these enzymes in protecting the endothelium from the damaging effect of free radical peroxidation.

[Free Radical Processes Play an Important Role in the Etiology and Pathogenesis of Atherosclerosis and Diabetes].

In this review, we present with exhaustive completeness the data of foreign studies and results of many years of own research, evidencing of the important role of free radical processes in the etiology and pathogenesis of atherosclerosis. The review contains the rationale for the concept that oxidative stress in atherosclerosis is even more developed during disorders of carbohydrate metabolism, contributing to the emergence of carbonyl stress in diabetes. We hypothesize that there exists a single common molecular mechanism of primary preatherogenic damages of vessel walls in atherosclerosis and diabetes, which enhances the formation of carbonyl-modified low-density lipoproteins to be accumulated in the foam cells. Possible reasons for failure of "antioxidant therapy" of atherosclerosis are discussed.

[Impact of a cold wave on disease course, hemodynamics, carbohydrate metabolism, and blood rheological properties in cardiac patents].

AIM: To study the impact of cold waves on disease course, hemodynamics, lipid and carbohydrate metabolisms, oxidative stress, and blood rheological properties in patients with cardiovascular diseases (CVD). SUBJECTS AND METHODS: 24 men and 36 women (their mean age was 62.9±9.7 years) were examined; coronary heart disease (CHD) and hypertension were present in 40 and 95% of the patients, respectively; selected therapy remained unchanged throughout the entire period. The investigators measured blood pressure and pulse wave velocity (PWV), carried out biochemical blood tests, estimated plasma oxidized low-density lipoproteins (oxLDL) and malondialdehyde (MDA) and erythrocyte superoxide dismutase (SOD) activity, calculated a MDA/SOD ratio, determined blood viscosity; as well as assessed quality of life using a visual analogue scale (VAS) and a specially developed questionnaire. RESULTS: Female sex, CHD, type 2 diabetes mellitus (DM-2) were independent predictors of cardiovascular events (CVEs) in the frost period. The persons who had experienced CVEs in frost had higher baseline PWV. CVEs, such as hypertensive crisis, emergency calls, cardiac arrhythmias, and the larger number of adverse reactions, were more commonly recorded in frost. There was an increase in blood glucose levels, a decrease in oxLDL, a rise in η2/η1, and a reduction in plasma viscosity during frost and elevated glycation end product levels at visit 2. Conclusion. The cold wave is associated with the larger number of CVEs in some patients with CVD during selected therapy. CHD, DM-2, female sex are independent predictors of CVE in patients with CVD during the winter period. In this period, there were increases in the levels of glucose, glycation end products, and erythrocyte aggregation, and a reduction in plasma viscosity.

Fructose as an inducer of free radical peroxidation of natural lipid-protein supramolecular complexes.

D-fructose strongly stimulates peroxidation of natural lipid-protein supramolecular complexes in vitro regardless of the oxidation initiation method. Fructose (ketose) intensifies free radical peroxidation to a much greater extent than glucose (aldose), which is important for the etiology and pathogenesis of diabetes mellitus.

[Using meldonium to improve the adaptation of patients with cardiovascular disease to the effects of heat and correction of associated oxidative stress].

Given that prolonged exposure to extreme climatic situations may play a role independent of stress factors, influencing the course of the underlying disease, the authors considered appropriate assessment of the effectiveness of additional prophylactic administration of drugs that increase the body's resistance to stress (adaptogens). The purpose of the study - to evaluate the effect of oxidative stress on meldonium, hemodynamics and quality of life of patients with cardiovascular disease (CVD) in extreme climatic conditions (summer heat). The study included 56 patients with CVD aged 38-75 years. Patients were randomized into two groups: active management (M), which in addition to basic therapy during 3 summer months received meldonium (500 mg/day), and control. The following parameters were measured: office blood pressure (BP), blood plasma malondialdehyde (MDA), erythrocyte superoxide dismutase (SOD) activity, level of oxidized low-density lipoprotein. MDA/SOD ratio was calculated. Visual analogue scale was used for assessment of quality of life. Meldonium treated patients demonstrated marked reduction of systolic BP and heart rate during heat, increased sodium level at the 2nd visit, improved quality of life. These changes corresponded to adaptive responses of healthy men. No significant dynamics of these parameters occurred in control group. MDA level during heat increased in both groups (p<0.05) but MDA/SOD ratio, which characterizes the "oxidation potential" of blood, increased significantly during the summer heat only in the control group. Meldonium can be used as an adaptogen in CVD patients during the summer heat.

[The influence of glucose on the free radical peroxidation of low density lipoproteins in vitro and in vivo].

It was shown that glucose in concentration 12.5-100 mM stimulated of Cu(2+)-mediated free radical peroxidation of low density lipoproteins (LDL) from human blood plasma. On the base investigation of kinetic parameters of LDL peroxidation it was stated that intensification of this process in the conditions of our experiments is caused by formation of free radical intermediates of glucose autoxidation during active oxygen species generation in the presence of metal ions with variable valence. It was found that glucose level normalization in the blood of patients with type 2 diabetes during therapy accompanied by significant decreasing of LDL oxidizing. During therapy with sugar-lowering drug metformin which utilizate methylglyoxal the LDL peroxidation from blood diabetes mellitus in vivo inhibited in more higher degree probably in consequence of decreasing of methylglyoxal-dependent generation of superoxide anion radicals as was shown by us early [Biochemistry (Moscow), 2007, 72: 1081-1090; Biochemistry (Moscow), 20(09, 74: 461-466].

[The role of oxidative processes in augmentation of atherogenity of low density lipoprotein particles].

We investigated action of natural dicarbonyl compounds which are formed in atherosclerosis and diabetes on properties of low density lipoproteins (LDL) such as surface charge, conformational changes of apoB100, susceptibility to oxidation. and aggregation rate. It was found that malonic dialdehyde (MDA) compared with glyoxal and methylglyoxal is more effective modificating agent of protein part of LDL particle. Nevertheless glyoxal and methylglyoxal-dependent modification of LDL can accelerate processes of further free radical peroxidation increasing atherogenity of LDL particles.

Macrophages actively accumulate malonyldialdehyde-modified but not enzymatically oxidized low density lipoprotein.

In this study, we show that low density lipoproteins (LDL) from human blood plasma which was oxidized by animal C-15 lipoxygenase is taken up by cultivated human macrophages with the same effectiveness as with non-oxidized (native) LDL. At the same time malonyldialdehyde-modified LDL is captured by cultivated macrophages very actively. Based on differences in catabolism of LDL with various levels of primary and secondary products of free-radical oxidation, it was offered to discriminate between the oxidized LDL itself (lipohydroperoxide-rich LDL) and the LDL that was chemically modified by free-radical oxidation secondary products of aldehyde nature. In this respect, aldehyde-modified but not oxidized (lipohydroperoxide-containing) LDL is atherogenic.

[The influence of natural dicarbonils on the antioxidant enzymes activity in vitro and in vivo].

Natural dicarbonyls, which may be accumulated during oxidative stress in atherosclerosis (e.g. malondialdehyde) or carbonyl stress in diabetes mellitus (glyoxal and methylglyoxal) effectively inhibited the activities of commercial preparations of antioxidant enzymes: catalase, Cu, Zn-superoxide dismutase (Cu, Zn-SOD) and Se-contained glutathione peroxidase from human and bovine erythrocytes and also rat liver glutathione-S-transferase. After incubation of human erythrocytes with 10 mM of each investigated dicarbonyls the decrease of intracellular Cu, Zn-SOD was observed. The decreased activity of erythrocyte Cu, Zn-SOD was also detected in diabetic patients with carbohydrate metabolism disturbance but effective sugar-lowered therapy was accompanied by the increase of this enzyme activity. The increase of erythrocytes activity of Cu, Zn-SOD of diabetic patients theated with metformin (which may utilize methylglyoxal) was higher than in erythrocytase of diabetic patients subjected to traditional therapy.