[Investigation of peroxide modification of low- and very low-density lipoproteins in patients with coronary heart disease by the method of fluorescent spectroscopy].

In the total fraction of low and very low density lipoproteins (LDL+VLDL) isolated from serum by precipitation in the presence of heparin-Mn the copper-induced lipid peroxidation was accompanied by accumulation of LPO products, a decrease ANS fluorescence intensity (F(ANS)) and an increase in probe--cation DSP-6, a fluorescence intensity decrease of intrinsic in the ultraviolet area (F(uv)) and an increase in the visible area (F(vis)). The degree of lipoprotein modification was estimated by calculating the F(vis)/F(uv) and F(DSP)-6/F(ANS) ratio. Strong positive correlation was found between these ratios and concentration of thiobarbituric acid-reactive substances (TBARS) of LDL+VLDL samples isolated from sera of 49 donors and incubated at 37 degrees C in the presence of 50 M CuSO4 during 0, 3 and 24 hr (F(vis)/F(uv) (r = 0.75; p < 0.001) and F(DSP-6)/F(ANS) (r = 0.73; p < 0.001)). Very strong positive correlation was also found between both fluorescent parameters F(vis)/F(uv) and F(DSP-6)/F(ANS) (r = 0.95, p < 0.001). Changes in the values of F(vis)/ F(uv), F(DSP-6)/F(ANS), concentration of TBARS in 75 patients with documented coronary heart disease (CHD) and 49 apparently healthy donors were studied. No significant differences of these parameters in LDL+VLDL of patients with CHD and donors were found.

[Study of blood cholesterol and triglycerides in patients with acute myocardial infarction].

The levels of cholesterol (C) and triglycerides (TG) were studied by a standard biochemical assays and the amount of C and TG was examined by a fluorescence assay in 55 patients with complicated (n=32) and uncomplicated (n=23) acute myocardial infarction (AMI) and in 25 apparently healthy donors. The content of C did not differ significantly in the study groups. As compared with the controls, the patients with complicated AMI had lower values of C + TG (p < 0.01) and TG (p < 0.001). In the patients with uncomplicated AMI, these indices were also lower than those in the control, but not significantly. The patients with complicated AMI were found to have insignificantly lower levels of TG and C + TG than those with uncomplicated AMI. The lower level of TG seems to be responsible for the decreased C + TG amount detectable in AMI by a fluorescence assay.

[Analysis of the amount of plasma cholesterol and triglycerides in patients with coronary heart disease].

Fluorescence technique was used to study the time course of changes in the amount of blood cholesterol and triglycerides (C+TG) in 43 patients with Q- and non-Q-wave myocardial infarction (MI) on days 1, 2, 3, and 10 of the disease, in 82 patients with chronic coronary heart disease (CHD), and in 43 apparently healthy donors. Within the first 3 days of the disease, the level of C+TG in the patients with acute MI (AMI) was significantly lower than that in the patients with chronic CHD and in the donors. By day 10 of their hospital stay, the level of lipids in patients with AMI increased and reached the levels observed in the control group.

Autofluorescence of low-density lipoproteins modified as a result of autooxidation.

Autooxidation of low-density lipoproteins during incubation at 37 degrees C was accompanied by accumulation of LPO products, decrease in UV autofluorescence (FUV), and increase in autofluorescence in the visible band (FVIS). The degree of low-density lipoprotein modification was estimated by calculating the FVIS/FUV ratio. A positive correlation was revealed between this ratio and concentration of thiobarbituric acid-reactive LPO products (r=0.76, p<0.001). Autooxidation of low-density lipoproteins increased availability of tryptophanyls for fluorescence quenchers and inductive resonance energy transfer from tryptophanyls to adducts formed in the reaction of apoprotein and LPO products. These changes probably play a role in the decrease in FUV.

Changes in surface charge of low-density lipoproteins during oxidative modification.

The negative surface charge of low-density lipoproteins increased during their oxidative modification induced by autooxidation at 37 degrees C. The degree of changes depended on the time of autooxidation: the surface charge remained practically unchanged after short-term oxidation (6-h incubation), but then progressively increased and after 24-h oxidation it 2-fold surpassed the initial level. Long-term incubation of low-density lipoproteins in the presence of EDTA inhibiting lipid peroxidation did not change their surface charge. These changes probably contribute to atherogenic activity of oxidized low-density lipoproteins. The degree of oxidative modification of low-density lipoproteins was precisely estimated using fluorescence probes.

[Molecular mechanisms of the effects of sodium hypochlorite on thrombocytes and lipoproteins]. / Molekuliarnye mekhanizmy deistviia gipokhlorita natriia na trombotsity i lipoproteiny.

Hypochlorite seems to inhibit platelet aggregation in the platelet-rich plasma (PRP) by modifying fibrinogen receptors. The hypochlorite-inactivated isolated platelets are completely repaired by native plasma. Platelet aggregation in PRP is suppressed by hypochlorite by its direct interaction with cells and indirectly due to plasma modification. The indirect action of hypochlorite is a reversible reaction between the platelet active groups and the products of plasma modification. The reaction may involve sulphur-containing groups. The spin-probe method shows that hypochlorite penetrates into the lipid phase of human blood lipoproteins. It initiates lipid peroxidation and causes the disturbance of the lipid structure and the protein please.

Peroxidation of human blood lipoproteins induced by exogenous hypochlorite or hypochlorite generated in the system of "myeloperoxidase + H2O2 + Cl-".

Oxidation of human plasma lipoprotein (LP) was studied in the presence of exogenous hypochlorite anion (OCl-) or OCl- generated in the "myeloperoxidase + H2O2 + Cl-" system. OCl- effectively initiates peroxidation of lipids extracted from LP and those within LP particles, as can be judged from accumulation of secondary (thiobarbituric acid [TBA] reactive) and final (Schiff bases) products of lipid peroxidation (LPO) in LP after incubation with myeloperoxidase or exogenous OCl-. Very low density and low density lipoproteins classified as atherogenic LP are more sensitive to OCl(-)-induced LPO than high density lipoproteins. These data allow us to propose that OCl- secreted by activated neutrophils and monocyte-macrophages can produce oxidative modification of LP in vivo. The latter is known as a risk factor in the development of atherosclerosis.

[Fluorescent method of determination of serum albumin in hyperbilirubinemia]. / Fliuorestsentnyi metod opredeleniia al'bumina v syvorotke krovi pri giperbilirubinemii.

A procedure is developed for estimation of human blood serum albumin in hyperbilirubinemia using a fluorescent probe 9,10-dianiline-2-sulfoanthracene (K-33). Use of the probe N-phenyl-I-amino-8-sulfonaphthalene (ANS) led to underestimation of albumin in hyperbilirubinemia as bilirubin and other inhibitors prevented the ANS binding with blood serum albumin. Substitution of ANS for K-33 enabled to estimate the albumin concentration under conditions of the pathology accompanied by an increase of endogenous ligands content in blood serum. The rate of K-33 (15 mM) fluorescence in blood serum (diluted 400-fold, at pH 4.0) correlated with albumin concentration (r-0.955).