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Biomedical subjects

O M Panasenko

Publications and source records attributed to O M Panasenko.

At least 55 records · Page 3Linked to original sources
PubMed1991

Antioxidant properties of albumin during the oxidation of linolenic acid and low density lipoproteins in the presence of ferrous ions.

A spin-labelled fatty acid with an epr spectrum that is sensitive to the localization of the probe was used to show that albumin binds free fatty acids present in solution and also free fatty acids present in low density lipoproteins (LDL). Furthermore, albumin binds the thiobarbituric acid-reactive (TBA-reactive) products formed during the oxidation of linolenic acid, whereas the TBA-reactive substances formed during the oxidation of LDL are not bound by albumin. Linolenic acid bound to albumin essentially does not undergo peroxidation in the presence of ferrous ions, in contrast to a suspension of linolenic acid and LDL in which peroxidation occurs quite readily in the presence of ferrous ions. The highest rate of oxidation was found for linolenic acid alone. Albumin-bound spin-labelled fatty acid was essentially not reduced by ferrous ions, whereas free fatty acid or fatty acid incorporated into LDL was reduced quite rapidly, the highest rate of reduction being for free fatty acids. Thus the ability of fatty acids to undergo oxidation correlates with their accessibility to ferrous ions. The data obtained indicate that serum albumin is a relatively effective antioxidant in the blood and its mode of action is based on the immobilization of free fatty acids.

Animals↗
PubMed1991

Free-radical generation by monocytes and neutrophils: a possible cause of plasma lipoprotein modification.

The activation of freshly isolated human blood monocytes and neutrophils monitored by oxidized human plasma lipoproteins (LP) was measured by detecting luminol-amplified chemiluminescence. The activation was accompanied by production of superoxide radicals. This finding was confirmed by measuring superoxide dismutase-sensitive reduction of cytochrome c. Incubation of monocytes or neutrophils with low-density lipoproteins (LDL) resulted in the accumulation of lipid peroxidation (LPO) products which were assayed by the 2-thiobarbituric acid test. Data from inhibitory analysis suggest that the hydroxyl radical scavenger, mannitol, had no appreciable effect on the accumulation of LPO products during the incubation of LDL with either cell type. However, catalase, superoxide dismutase, the metal ion chelators desferrioxamine and EDTA, as well as the free radical scavenger, butylated hydroxytoluene, markedly decreased the accumulation of LPO products in the medium--by 88%, 67%, 38%, 52%, and 47%, respectively, after incubation of LDL with monocytes, and by 65%, 47%, 41%, 65%, and 100% after incubation of LDL with neutrophils. These results indicate that activation of monocytes and neutrophils by oxidized LP intensifies LPO which proceeds via a free-radical mechanism that is superoxide-dependent and is catalyzed by transition metals.

Adult↗
PubMed1989

Free radical lipid oxidation affects cholesterol transfer between lipoproteins and erythrocytes.

Human erythrocytes were incubated for 5 h at 37 degrees C with lipoproteins (LP), preliminary oxidized to different extent, as assessed by thiobarbituric acid (TBA) test. Cholesterol content in the cells was increased by 12-14% after incubation with low-density lipoproteins (LDL) along with augmentation of order parameter and rotational correlation time of spin-labeled stearic acids incorporated into membranes. If erythrocytes were incubated with oxidized LDL, containing 2.5-4 times more TBA-reactive material than native ones, cellular content of cholesterol was increased by 24-28%. In contrast, high-density lipoproteins (HDL2 and HDL3) removed cholesterol from cell membranes, when incubated with erythrocytes. This was followed by increased fluidity of membrane lipid phase as detected by the spin probe method. Oxidation of HDL2 and HDL3 decreased their ability to accept cholesterol from cell membranes. No detectable accumulation of TBA-reactive material was observed in the samples during the incubation. The antioxidant, butylated hydroxytoluene (BHT), in the concentration of 10(-5) M did not influence the cholesterol transfer between LP and erythrocytes. Hence, the effects of lipid peroxidation (LPO) on the cholesterol transfer seem to result from LP alterations by oxidation rather than from free radical reactions occurring during the incubation. By increasing cholesterol-donating ability of LDL and inhibition of cholesterol-accepting capacity of HDL lipid peroxidation in LP may activate cholesterol accumulation in blood vessel cells and thus contribute to atherosclerosis.

Butylated Hydroxytoluene↗
PubMed1988

[Lipid peroxidation--the factor promoting cholesterol accumulation in cells in atherogenesis].

The cholesterol transfer between human erythrocytes and main classes of serum lipoproteins (LP) from healthy donors and artery-coronary disease patients was studied (artery-coronary disease is the main manifestation of atherosclerosis). It is shown that low-density lipoproteins (LDL) are capable of transporting cholesterol to erythrocytes, which lack the specific receptors for LDL. The cell cholesterol content in comparison with erythrocytes incubated without LDL was increased by 11.4%. The effect was even higher in case of LDL, isolated from serum of artery-coronary subjects (the cell cholesterol content was increased by 33.8%). High-density lipoproteins (HDL) accept cholesterol from cell membranes. However, cholesterol-accepting properties of HDL from artery-coronary disease patients were suppressed as compared with normal HDL. Both discovered events must promote the cholesterol accumulation in cell membranes in atherosclerosis. As it is shown by the spin probe method, lipid peroxidation (LPO) causes the disturbance of the structural organization of LP and as the consequence of that--the increase of LDL cholesterol-donating ability and the decrease of HDL cholesterol-accepting ability. The greater LDL are oxidized, the more cholesterol they transport to erythrocytes during incubation. The greater is the level of HDL peroxidation, the stronger their cholesterol-accepting function is suppressed. These results suggest that LPO can play an important role in LP modification, the disturbance of their interaction with cell surface and the cholesterol accumulation in cells in atherosclerosis.

Arteriosclerosis↗
PubMed1987

Alterations of surface charges of plasma lipoproteins in ischemic heart disease.

For a charged and an uncharged long chain spin probe the partition between the aqueous phase and the lipoproteins LDL, HDL2 and HDL3 was measured by use of ESR spectroscopy. The partition coefficients were compared for lipoproteins from normal donors and lipoproteins from patients with ischemic heart disease. The partition coefficients of the uncharged spin probe are not different. However, the charged spin probe has a significantly different partition for LDL and HDL3. This difference results from changes in the surface charge. Patients with ischemic heart disease have LDL which is more electropositively charged and HDL3 is more electronegatively charged compared to the corresponding lipoproteins of normal subjects. The surface charge of HDL2 is not changed. The results are discussed in the light of current concepts of the pathogenesis of atherosclerosis.

Coronary Disease↗
PubMed1986

[Changes in the surface charge of plasma lipoproteins during their auto-oxidation].

Low density lipoproteins (LDL) and high density lipoproteins (HDL) surface potential (charge) changes were studied upon autooxidation, using positively charged spin probes. Lipid peroxidation product accumulation in LDL and HDL suspensions was found to be accompanied by a significant reduction in their surface area associated with a decreased negative surface charge, and probably, deposition of lipid peroxidation polar products and/or surface charge redistribution as a result of lipoprotein autooxidative modification.

Coronary Disease↗
PubMed1986

[Changes in the surface potential of plasma lipoproteins in ischemic heart disease. Studied with spin probes].

Changes in lipoprotein surface potentials were studied by a positively charged analog as a spin probe. Low density lipoproteins (LDL) and high density lipoproteins (subfractions HDL2 and HDL3) of patients with coronary heart disease (CHD) were studied. CHD patients have revealed a significant decrease (by 14.4 +/- 0.3 mV) in LDL and an increase (by 6.3 +/- 2.0 mV) in HDL3 negative surface potential, as compared to the control. The increase in HDL2 surface potential in CHD patients was insignificant (1.9 +/- +/- 2.5 mV). The possible role of LDL and HDL3 surface potential changes in the mechanism of interaction of these types of lipoproteins with vascular wall and blood cellular membranes and in pathogenesis of CHD and atherosclerosis is discussed.

Coronary Disease↗
PubMed1985

[Structural changes in erythrocyte membranes in nephropathy].

Spin probes were used to study alteration of red cell membranes in nephropathy of varying degree of gravity. Iminoxyl radicals of the lipid nature were applied as spin probes, in particular 2-(3-carboxypropyl)-4,4-dimethyl-2-tridecyl-3-oxazolidinyl (probe I). It was shown that in nephropathy, the orderliness parameter increases and the hydrophoby of probe I localized in a red cell suspension of nephropathy patients diminishes as compared with analogous parameters in healthy pregnant women. This attests to both immobilization of the fatty acid chains of phospholipids and to an increase in the polarity of the lipid bilayer in the area of probe localization. It was established that diminution of probe I hydrophoby is in a satisfactory agreement with the disease gravity and the degree of edema in patients. It was noted that alterations discovered in red cell membranes in nephropathy are similar to those seen during activation of lipid peroxidation in membranes. The possibility of lipid peroxidation involvement into the pathogenesis of nephropathy is discussed.

Electron Spin Resonance Spectroscopy↗
PubMed1984

[Characteristics of the structural organization of lipoproteins in the blood plasma of patients with ischemic heart disease using the spin probe method].

Structural properties of lipoprotein organization in blood plasma of the patients with ischemic heart disease have been studied by means of electronic paramagnetic resonance method, using a derivate of stearic acid (5-doxylsteararte) as a spin probe. Significant differences in the patterns of thermo-induced structural reorganizations of all the lipoprotein types in normal and pathological states were shown. However, these differences were not found in the lipids isolated from the lipoproteins. In high density lipoproteins HDL2 and HDL3 from blood plasma of the patients with ischemic heart disease a decrease in the micro-environment polarity was shown to take place at the depth of 8 A from the lipoprotein surface. The data obtained suggest the distinct changes in structural organization of all the lipoprotein types in heart ischemic disease, which appear to occur as a result of modification of apoproteins and/or protein-lipid interactions in lipoproteins.

Coronary Disease↗
PubMed1984

[Thermotropic structural rearrangements in blood plasma lipoproteins in ischemic heart disease].

Structural properties of blood plasma lipoproteins (LP) from coronary heart disease (CHD) patients were examined. Substantial differences were found in the pattern of the heat-induced structural restitution of LP of all classes in health and disease. At the same time no such differences were discovered in lipids isolated from LP. In high density lipoproteins from the plasma of CHD patients, a decrease in the microenvironmental polarity was shown to take place at a depth of 8 A from the surface of LP. The data obtained indicate substantial changes in the structural organization of LP of all classes in CHD. It is assumed that these changes are consequent on the modification of apoproteins and/or protein-lipid interactions in LP.

Coronary Disease↗
PubMed1983

[Thermo-induced structural changes in lipoproteins of human plasma, studied with spin probes].

The thermo-induced structural changes in lipoproteins (LP) of human plasma were investigated by the electron paramagnetic resonance method, using 5-doxylstearate as a spin probe. LP were shown to undergo thermotropic transformations at temperatures specific for each LP type. Differences were found in the nature of temperature dependences of the order parameter for the probe localized in LP and for isolated lipids. The denser the LP, the more pronounced the differences. 5-Doxylstearate was shown to be localized not only in the lipid phase of LP, but also in the area of the protein--lipid contact. This indicates that 5-doxylstearate is a useful tool for the study of protein--lipid interactions in pathological processes coupled with their modifications.

Cyclic N-Oxides↗
PubMedDate not supplied

[Interaction of tert-butyl hydroperoxide with hypochlorite induces peroxyl radicals. A chemiluminescence study].

The interaction of hypochlorite (HOCl/OCl-) with tert-butyl hydroperoxide ((CH3)3COOH) was investigated by chemiluminescence. It was shown that the addition of HOCl/OCl- to (CH3)3COOH induces a fast chemiluminescent flash. The intensity of this flash increases with the increase in both HOCl/OCl- and (CH3)3COOH concentration. The chemiluminescence is quenched in a concentration-dependent manner in the presence of free radical spin traps N-tert-butyl nitrone and alpha-(4-pyridyl-1-oxyl)-N-tert-butyl nitrone. This fact proves that free radicals take part in the interaction of HOCl/OCl- and (CH3)3COOH. Hypochlorite yielded a very similar chemiluminescence spectrum in its reaction with (CH3)3COOH as Ce4+. It differed considerably from the spectrum in the system H2O2 and HOCl/OCl-. It is well known that the interaction of Ce4+ and (CH3)3COOH produces peroxyl radicals. These results confirm the hyothesis that the interaction of HOCl/OCl- and (CH3)3COOH is mediated by peroxyl radicals. Thus, organic hydroperoxides always present in unsaturated lipids can induce lipid peroxidation processes in the reaction with HOCl/OCl-.

Electron Spin Resonance Spectroscopy↗
PubMedDate not supplied

[The interaction of hypochlorite with fatty acid hydroperoxides results in the generation of free radicals].

The interaction of hypochlorite with linoleic acid hydroperoxides was studied by the coumarin C-525-enhanced chemiluminescence and ESR spin trapping techniques. Linoleic acid hydroperoxide was obtained in the reaction of lipoxygenase and linoleic acid. Alpha-(4-pyridyl-1-oxyl)-N-tert Butylnitron was used as a spin trap. It was shown that the addition of hypochlorite to the incubation media containing linoleic acid and lipoxygenase resulted in an intensive chemiluminescence flash. The intensity of this flash correlated with the hydroperoxide concentration. The analysis of ESR spectra of spin adducts produced in the reaction of hypochlorite with linoleic acid hydroperoxide showed the presence of O-centered, most likely peroxyl, radical with the splitting constants alphabetaH = 0.260 mT aN = 1.662 mT and C-centered penthyl radical with the splitting constants alphabetaH = 0.260 mT; aN = 1.662 mT. These data suggest that hypochlorite produced by phagocytes in vivo can induce the generation of free O- and C-centered radicals, promoters of free radical processes.

Electron Spin Resonance Spectroscopy↗