Biomedical subjects

A A Mel'nichenko

Publications and source records attributed to A A Mel'nichenko.

7 recordsLinked to original sources

PubMed2005

Desialylation decreases the resistance of apo B-containing lipoproteins to aggregation and increases their atherogenic potential.

Subfractions of apo B-containing lipoproteins (VLDL and intermediate-density lipoproteins) with reduced content of sialic acid were found in human blood. These lipoproteins are characterized by high capacity to spontaneous association (aggregation) and stimulated accumulation of cholesterol in smooth muscle cells of human aortic intima. In vitro treatment of apo B-containing lipoproteins with alpha-2,6-sialidase and alpha-2,3-sialidase stimulated aggregation and increased the ability of these particles to potentiate cholesterol accumulation in smooth muscle cells of the intact human aortic intima. Probably, desialylation of various apo B-containing lipoproteins can occur in the blood; this process decreases their resistance to aggregation, and increases the ability of these particles to stimulate accumulation of cholesterol in human aortic intima cells, i.e. increases their atherogenic potential.

Analysis of Variance↗

PubMed2005

Phospholipid hydrolysis with phospholipases A2 and C impairs apolipoprotein B-100 conformation on the surface of low density lipoproteins by reducing their association resistance.

Modification of apolipoprotein B-100 conformation on the surface of LDL isolated from human blood was demonstrated by enzyme immunoassay with a panel of monoclonal antibodies to this protein. The study by the light transmission fluctuation method showed that incubation of LDL with phospholipases A2 or C led to association of LDL particles. This lipolytic modification seems to impair LDL surface properties inducing association of these particles, which can play an important role in lipid accumulation in the vascular wall and at early stages promote the development of atherosclerosis.

Apolipoprotein B-100↗

PubMed2005

Proteolysis of apoprotein B-100 impairs its topography on LDL surface and reduces LDL association resistance.

Serine proteinases (trypsin and chymotrypsin) cause destruction of apolipoprotein B-100 on the surface of human blood LDL. Incubation of LDL with these enzymes increases the mean size of LDL particles. Proteolysis of apolipoprotein B-100 induces changes in surface structure, destabilizes LDL particles, and reduces their association resistance. Presumably, this proteolytic modification of LDL with subsequent association of these particles plays an important role in accumulation of cholesterol in the vascular wall and in the development of early stages of atherosclerosis.

Agglutinins↗

PubMed2004

Low ionic strength promotes association of circulating modified LDL in human blood.

The resistance to association of circulating multiply-modified low-density lipoproteins (LDL) isolated from human blood and characterized by a decreased content of sialic acids in comparison with native LDL was studied by analysing light transmission fluctuations. LDL association was stimulated by decreasing environmental ionic strength. It is established that circulating modified LDL are less resistant to association than native LDL. Association of LDL in a medium with low ionic strength was irreversible. Probably, increased capacity to irreversible association determines the atherogenic properties of circulating modified LDL subfraction.

Arteriosclerosis↗

PubMed2004

Resistance of native and circulating modified low-density lipoproteins in human blood to association.

The resistance of native and circulating modified low-density lipoproteins from human blood to spontaneous and polyethylene glycol-induced association was studied by recording light transmission fluctuations. Circulating modified low-density lipoproteins were less resistant to association than native low-density lipoproteins. Polyethylene glycol-induced association of low-density lipoproteins was irreversible. Our results suggest that atherogenic activity of circulating modified low-density lipoproteins is associated with their increased predisposition to irreversible association.

Arteriosclerosis↗

PubMed2004

Antigenic differences between apo-B in native and circulating modified low-density lipoproteins.

The state of apo-B in native and circulating modified low-density lipoproteins was studied by solid-phase enzyme immunoassay. We studied the interaction of these particles with monoclonal antibodies to apo-B of low-density lipoproteins. Native and circulating modified low-density lipoproteins had different affinity for the studied antigens. Our results illustrate conformational changes in apo-B of circulating modified low-density lipoproteins compared to native low-density lipoproteins. These changes probably contribute to increased accumulation of particles in vascular cells and their transformation into foam cells giving way to atherosclerotic vascular lesions.

Antibodies, Monoclonal↗

PubMedDate not supplied

[A comparative study of the lipid phase in native and circulating multiple-modified low-density lipoproteins of human blood by the use of the spin probe method].

Different approaches based on the spin probe method were used to compare the physical state of the surface lipid monolayer in subfractions of low-density lipoproteins: in native low-density lipoproteins constituting the bulk of human blood low-density lipoproteins and in circulating multiple-modified low-density lipoproteins whose portion is minor in healthy persons but significantly increases in atherosclerotic patients. The data obtained in in vitro experiments suggest that circulating multiple-modified low-density lipoproteins possess atherogenic properties. The order parameter S, rotational correlation time tau, and hydrophobicity parameter h were calculated from electron spin resonance spectra of a series of spin probes whose paramagnetic groups are located at different depths of the lipid monolayer. These parameters characterize the molecular packing, fluidity, and polarity in the microenvironment of paramagnetic groups. The kinetics of the reduction of paramagnetic groups by ascorbate and oxidation by hypochlorite were obtained for the spin probe whose paramagnetic group is located deeply in the lipid monolayer at the level of the terminal segments of phospholipid acyl chains. No difference between native low-density lipoproteins and circulating multiple-modified low-density lipoproteins was revealed in respect of the physical properties of the lipid domain of surface proteolipid layer, as sampled by spin probes.

Arteriosclerosis↗