Results of the study of the pathophysiological effects of dysregulation of free-radical processes: deadlock or a new impulse?

The review presents the results of the authors' work of many years and the data of foreign studies, indicating the importance of free radical processes in etiology and pathogenesis of atherosclerosis. The justification of the idea that oxidative stress in atherosclerosis develops more often during disorders of carbohydrate metabolism, contributing to emergence of carbonyl stress in diabetes. It is hypothesized that there is a single molecular mechanism of primary pro-atherogenic injuries of vessel walls in atherosclerosis and diabetes, which enhances the formation of carbonyl-modified low-density lipoproteins, accumulating in the foam cells. The results of recent studies indicate that oxidatively modified LDL involved not only the primary injury to the vessel walls, but also provoked the development of endothelial dysfunction, so that once again raises the issue of the need for the use of antioxidants to prevent injuries in vascular walls. It can be assumed that the result of years of intensive research of free radical process mechanisms in atherosclerosis and diabetes will be the development of new drugs for the combined therapy of these diseases that can be disposed not only reactive oxygen species and organic free radicals and reactive carbonyls, which are clearly playing an important role in the development of pro-atherogenic injuries

Oxidative stress in hyperthermia

Oxidative stress is a risk factor for disease development and cardiovascular system, diabetes, neurodegenerative diseases, etc. The resulting product is thus free radical lipid peroxidation - malondialdehyde (MDA) is atherogenic modification of low density lipoproteins (LDL), so that they acquire the ability to be rapidly accumulated in the cells of the vessel walls, causing pre-aterosklerotic lipoid damages. The aim of this study was to investigate the effect of high temperature (one of the environmental factors) for key operating parameters: the content of secondary products of free radical oxidation polyene lipids - mDa in blood plasma and erythrocyte antioxidant activity of key enzymes. Hyperthermia was triggered in practically healthy volunteers (6 males, 22-46years). The analysis was made using a recording spectrophotometer Hitachi-557 (Japan). The statistical analysis was performed using the non-parametric Wilcoxon-test (Attestat program). MDA levels in the blood plasma, the activity of key antioxidant enzymes in erythrocytes were determined through divided intervals in study participants. A significant increase in MDA content (62 %) and reduction of catalase activity (11 %) and glutathione peroxidase (19 %) were revealed after 30 days in the conditions of hyperthermia test

Modification of low-density lipoproteins by low molecular weight carbonyl products of free-radical oxidation of lipids and carbohydrates plays a key role in atherosclerotic lesion of the vascular wall and in endothelial dysfunction

The review presents evidence of the participation of low-density lipoproteins (LDL) modified by low molecular weight dicarbonyl compounds formed during freeradical oxidation of lipids (malondialdehyde) and carbohydrates in the development of endothelial dysfunction and atherosclerotic vascular lesions. The authors believe that it is they, and not oxidized (hydroperoxide-containing) LDL, that are the main factors of pathogenesis. The role of dicarbonyl-modified LDL in LOX-1 dependent induction of processes leading to the development of endothelial dysfunction is discussed. The results of studies proving that damage to the glycocalyx (a layer of macromolecules that prevent the development of endothelial dysfunction) covering the luminal surface of the endothelium is caused by hyperproduction of reactive oxygen species. Ways of pharmacological correction of free-radical oxidation processes are discussed, due to which inhibition of atherogenesis and diabetogenesis can be achieved

Clearance of carbonyl-modified lipoproteins from the bloodstream of rabbits

We have suggested that the molecular mechanism of vascular wall damage in diabetes is not substantially different from that in atherosclerosis. Thus, it can be assumed that aldehyde-modified LDL should be eliminated from the blood stream with much greater speed than non-oxidized LDL. In the available literature there is information about the clearance of native human LDL from the bloodstream, whereas information on the clearance of the aldehyde-modified LDL in animals or humans was not found. Based on this, the present work is devoted to the clearance of aldehyde-modified LDL of rabbits and humans introduced into the bloodstream of rabbits. We investigated the clearance of glyoxal-, methylglyoxal- and MDA-modified LDL from the bloodstream of rabbits. We used biotinylated LDL of rabbit blood plasma and FITC-labeled LDL of human blood plasma. LDL was isolated with preparative ultracentrifugation in NaBr gradient. It was shown that glyoxal- and methylglyoxal-modified LDL of rabbits and humans circulated in the bloodstream for the same time as native LDL while MDA-modified LDL was rapidly eliminated from the bloodstream. The data obtained indicated the possibility of greater atherogenic potential of glyoxal- and methylglyoxal-modified LDL as they circulate in the bloodstream for a rather long time. At the same time, MDA-modified LDL is likely to be exposed to enhanced elimination by macrophages after their "linkage" to blood cells

Regulation of free radical processes in healthy volunteers during experimental hyperthermia and in patients with coronary artery disease during summer heat waves

Background. In view of the worsening forecast for global temperature rise worldwide, it seems relevant to study the effects of abnormal heat waves on systemic regulatory processes in people with chronic diseases, in particular coronary artery disease (CAD).Aims. This study aimed to investigate the effect of hyperthermia on oxidative stress parameters in patients with various severity of CAD and in healthy subjects.Materials and methods. We studied the level of malonic dialdehyde (MDA) and the activity of Cu,Zn-containing superoxide dismutase (Cu,Zn-SOD) in healthy subjects under conditions of 30-day long simulated hyperthermia and in patients with different severity of CAD after the summer heat wavesResults. We revealed signs of oxidative stress in healthy volunteers during model hyperthermia that manifested as an increase in content of MDA in blood plasma. At the  same time we observed increasing activity of Cu,Zn-SOD in erythrocytes that  utilizes reactive oxygen species. The increase of Cu,Zn-SOD activity started with a certain latency what also can be explained by de novo enzyme biosynthesis induction. We also studied oxidative stress parameters in patients at high and moderate cardiovascular risk according to the SCORE risk chart with uncomplicated CAD course and in patients with complicated CAD with severe coronary damage according to angiography during the summer heat waves. We observed accumulation of MDA in blood plasma and increasing activity of erythrocyte Cu,Zn-SOD in patients with uncomplicated CAD. At the same time we noted that accumulation of MDA in blood plasma was not followed by any increase in activity of red blood cell Cu,Zn-SOD in patients with severe complicated CAD. This fact indicates dysregulation of free radical processes in patients with severe course of CAD during the heat waves.Conclusions. The dysregulation of free-radical processes in patients with a severe clinical course of CAD has been revealed

Impact of Atherosclerosis- and Diabetes-Related Dicarbonyls on Vascular Endothelial Permeability: A Comparative Assessment

Background. Malondialdehyde (MDA), glyoxal (GO), and methylglyoxal (MGO) levels increase in atherosclerosis and diabetes patients. Recent reports demonstrate that GO and MGO cause vascular endothelial barrier dysfunction whereas no evidence is available for MDA. Methods. To compare the effects of MDA, GO, or MGO on endothelial permeability, we used human EA.hy926 endothelial cells as a standard model. To study cortical cytoplasm motility and cytoskeletal organization in endothelial cells, we utilized time-lapse microscopy and fluorescent microscopy. To compare dicarbonyl-modified protein band profiles in these cells, we applied Western blotting with antibodies against MDA- or MGO-labelled proteins. Results. MDA (150–250 μM) irreversibly suppressed the endothelial cell barrier, reduced lamellipodial activity, and prevented intercellular contact formation. The motile deficiency of MDA-challenged cells was accompanied by alterations in microtubule and microfilament organization. These detrimental effects were not observed after GO or MGO (250 μM) administration regardless of confirmed modification of cellular proteins by MGO. Conclusions. Our comparative study demonstrates that MDA is more damaging to the endothelial barrier than GO or MGO. Considering that MDA endogenous levels exceed those of GO or MGO and tend to increase further during lipoperoxidation, it appears important to reduce oxidative stress and, in particular, MDA levels in order to prevent sustained vascular hyperpermeability in atherosclerosis and diabetes patients

Сholesterol lowering therapy and low density lipoprotein peroxidation during atherosclerosis

атеросклероз, статины, липопротеины низкой плотност