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It has been observed during influenza epidemics and in a number of population and clinical trials that this prevalent viral infection was associated with increased death rates from cardiovascular diseases. The clinical and experimental data that may explain accelerated coronary atherosclerosis in influenza infection with implications involving autoimmune mechanisms are analyzed in this article. Both cellular and humoral autoimmune modes could be proposed to participate in the onset or progression of atheromatous lesions due to influenza infection.

It was established that viral particles, like low-density lipoproteins (LDLP), when subjected to some modification changes, lost their ability to be internalized by tissue somatic cells and acquired tropism to macrophage cells. The data, obtained by us by using the polymerase chain reaction (PCR) method, made it possible to assert that atherosclerotic plaques, isolated from vessels of patients with ischemic heart disease (IHD) who underwent coronary bypass, contained RNA of the A(HINI) and AH3N3) influenza viruses. Whereas, the vessel portions, undamaged by atherosclerosis, did not contain any genetic substances of influenza viruses. It was for the first time that an experimentally supported understanding was expressed on that the atherosclerotic plaques serve as a "reservoir" for influenza viruses. It is also suggested that the mentioned plaques can be the carriers of influenza viruses for a long time, thus, prolonging the persistent form of influenza infection in the human body.

Aim: To study relationship between influenza virus infection and activity of clinical presentations of atherosclerosis., Methods and Results: Average blood level of IgG to influenza A virus was significantly higher in patients with progressing forms of ischemic heart disease then in patients without objective signs of exacerbation of atherosclerotic process. Mean titles of antibodies to parainfluenza virus and adenoviruses were similar in both groups of patients. Direct detection of viral DNA by polymerase chain reaction was carried out in samples of aortic wall taken during coronary artery bypass surgery with the use of primers for hemagglutinin of H1N1, H3N2 viruses. RNA of influenza virus was found in these samples., Conclusion: The presence of viral RNA in vascular atherosclerotic lesions could be indicative of possible pathogenetic role of influenza infection in progression of clinical course of atherosclerosis.

The cycloferon efficacy was investigated in the treatment of experimental herpesvirus kerato-conjunctivitis in rabbits. The model was demonstrated to reflect the main aspects of herpesvirus eye lesions in humans. Cycloferon application similarly to that of known interferon inducer poludan has been shown to enhance processes of inflammation and subsequent regeneration of eye tissues as well as to decrease mortality of animals due to the generalization of infection.

The method of in situ transcription was used to detect influenza virus genome in the organs of infected mice. Virus-specific RNA was found in the alveolar macrophages 5 months after infection, this confirming the capacity of the virus to persist in vivo in these cells for a long time. Evidence in favor of influenza virus modification in an infected host body is presented, which fact dramatically affects virus interactions with macrophages. Problems in the development of acute and persistent infections and influenza virus persistence in reticuloendothelial cells are discussed.

Low-density lipoproteins (LDL, d 1.0.40-1.053 g/ml) and high-density lipoproteins (subfraction 3 of HDL, d 1.210 g/ml) were isolated by preparative ultracentrifugation at the NaBr density gradient. The findings have led to the conclusion that LDL or beta-LP are not thermolabile, but they represent a thermoresistant serum virus-inhibiting factor. At the same time HDL3 has pronounced thermolabile properties. The mechanisms of action of the above factors are explained in the paper.

The experimental data obtained by immunological, immunomorphological, biochemical, and virological methods are presented which substantiate a concept that various strains of influenza virus under study may penetrate tissue cells at sites of high affinity usually meant for low-density lipoproteins (LDLP) providing the cells with cholesterol for construction of outer and inner membranes. A computer analysis of a bank of data on the primary structure of proteins (the package of GENBER programme) revealed significant similarity of amino acid sequences between the area of viral hemagglutinin site attachment to cells and corresponding amino acids comprising apoB LDLP. The presented proofs are a convincing example of virus particles mimicry realized at the molecular level and give new concepts concerning the mechanisms of virus penetration into body cells which are important for the development of a principally new approach to creation of highly effective antiviral compounds. Moreover, the observed phenomenon may serve for explanation of the nature and mechanism of action of the so-called thermostable virus-neutralizing blood serum inhibitor.

In experiments in vitro the electromagnetic field of 2375 mHz, 500 microW/cm2 was shown to influence peroxide modification of low density lipoproteids. It was also shown that this modifying effect was prevented by high density lipoproteids that decreased the level of lipid peroxidation.

After immunological sympathectomy in rabbits activity and isoenzyme spectra of hexokinase (HK) and lactate dehydrogenase (LDH) were studied in smooth muscle of stomach. Activity of KH in the muscles was statistically significant due to increase in content of a single isoenzyme of HK occurring in the tissue. Activity o LDH was unaltered. However the isoenzyme apectrum of the enzyme was changed: content of M-subunits was decreased and the content of H-subunits was increased. These alterations may lead to an increase in redox potential in cells of the tissues.

Experimental allergic encephalomyelitis an polyneuritis were caused in male rats of 2.5-3.0 kg body mass of the Shinshilla strain by means of administration into the foot of the animals pads of homogenous basic protein myelin from bovine spinal cord and myelin from bovine sciatic nerve as a mixture containing complete Freund's adjuvant. In the impaired rabbits total fraction of beta- and pre-beta-lipoproteins as well as content of cholesterol and triglycerides were increased in blood. Antibodies against the basic protein myelin were not found in blood of the animals with experimental allergic encephalomyelitis, whereas the titres of these antibodies were increased in the animals with experimental allergic polyneuritis. Complex formation of antibodies with beta- or pre beta-lipoproteins appears to take place in blood of the animals.

Experiments were carried out using 69 rabbit males with a body mass of 2.5-3.0 kg. Experimental allergic polyneuritis developed in the animals after administration into foot pads of the base neuritogenic proteins together with complete Freund's adjuvant. Content of cholesterol (CS) and triglycerides (TG) was increased more than 2-fold, concentration of the total fraction of beta- and pre- beta-lipoproteins was elevated 3-fold in blood plasma of rabbits within 1 hr after the treatment. Within 12 days after administration of the mixture another increase in the fractions studied was observed, reaching the maximal value within the 30 days of the experiment: content of cholesterol and triglycerides was increased 3-fold, total fraction beta- and pre- beta-lipoproteins--more than 4-fold. The ratio CS/TG was similar in blood sera of both normal and injured rabbits and was approximately equal to 0.4. The increase in permeability of aortal wall and its lipid infiltration were found at the same period.

Unspecific interaction was analyzed between native 125I-lipoproteins of low density (LDL) as well as 125I-LDL, maintained in rabbit circulation during 4 hrs, and fibroblasts and macrophages. Alterations in properties of the LDL, occurred in blood, were accompanied by an increase in their affinity towards macrophages and a decrease in the affinity to fibroblasts. In vivo effect of HDL on catabolism of LDL was manifested as inhibition of extracellular modification of LDL and elimination of them from circulation, and in vitro--as inhibition of the native LDL capture by fibroblasts and, especially, by macrophages. In vivo inhibitory effect of HDL on modification of LDL, which are captured by cells (including arterial endothelial cells) by means of unspecific endocytosis, appears to be one of mechanisms in the antiatherogenic action of HDL.

An analysis was made of catabolism of low density lipids (LDL) labeled in the protein or lipid moieties with cultivated human fibroblasts under inhibition of receptor-mediated endocytosis of LDL. The results have shown that under these conditions, only part of LDL uptaken by the cells are catabolized in the cells for 24 h. A considerable part account for a slow-metabolized intracellular pool. LDL of the latter may leave the cells by exocytosis (regurgitation), appearing in the culture medium. On the whole, the data obtained agree with the basic regularities of LDL transport in the cell within the structure of uncoated vesicles.

Immune complexes consisting of human [125I]LDL or [125I]VLDL and anti-apo B IgG were prepared in vitro. After intravenous administration of these complexes or free LDL to normal rabbits the elimination rate for complexes was 2-3-fold higher than for free lipoproteins. The liver/spleen radioactivity ratio after administration of immune complexes was 34% less than after administration of free lipoproteins. Investigations carried out on the cell cultures have shown that during 4-h incubation the uptake of [125I]LDL-anti-apo B IgG complex by human lung fibroblasts was lower than uptake of free [125I]LDL, whereas mouse peritoneal macrophages took up immune complex more actively than free LDL. During 3 days of incubation of macrophages with LDL-anti-apo B IgG the transformation of macrophages into foam cells was observed. This process was accompanied by almost a 60-fold increase of cholesteryl ester content in the cell. It is suggested that excessive uptake of lipoprotein-antibody complexes by macrophages leading to formation of foam cells may play an important role in atherogenesis.

Only one isozyme of hexokinase (type I) was found in a soluble fraction of smooth muscle of rabbit stomach using column chromatography and polyacrylamide gel electrophoresis. By the pattern of metabolism the smooth muscle of rabbit stomach accupies an intermediate position between rapidly and slowly contracting sceletal muscles, approaching to musculus soleus by the activity and isozyme spectra of hexokinase and lactate dehydrogenase (LDH). Activity of these enzymes was altered not uniformly in dissimilarly functioning muscles of rabbits with experimental allergic encephalomyelitis: it was increased in musculus gastrocnemius of rabbits and decreased in soleus or in smooth muscles. LDH isoenzyme spectra changed towards an increase in aerobic H-subunits and decrease in anaerobic M-subunits in the soluble fraction of musculus gastrocnemius of rabbits with experimental allergic encephalomyelitis. Content of LDH-5 and LDH-4 was about 2-fold increased and content of LDH-1 and LDH-2 was decreased in musculus soleus.

A homogenous base protein, exhibiting high encephalitogenic activity towards guinea pigs and rabbits, was isolated from bovine spinal cord using column chromatography. Administration of the preparation obtained together with Freund's adjuvant into the animals caused development of neurogic symptoms typical for experimental allergic encephalomyelitis as well as formation of demyelinization foci both in spinal cord and in brain of guinea pigs and rabbits.

Electron microscopy, disc electrophoresis in polyacrylamide gel, and microzonal electrophoresis on acetate cellulose were used to examine the changes in the properties of low density lipoproteins (LDL) in extracellular medium during incubation with human fibroblasts. It was established that as a result of LDL interaction with fibroblasts there appeared lipoprotein particles less in size, with higher aggregation ability and electrophoretic mobility. The data obtained indicate that LDL undergo physicochemical changes due to non-specific interaction with fibroblasts.

Main encephalitogenic protein was isolated from bovine medulla spinalis and separated into homogenous polypeptide fractions by gel filtration; some of these fractions had the high encephalitogenic activity. The main protein and its fractions, possessing the encephalitogenic activity, caused a development of cross-reacting antibodies and a sensitization to intracutaneous administration of encephalitogenic preparations in animals. Non-encephalitogenic main protein sensitized animals only to this protein and did not induce the formation of distinct amount of antibodies. The amino acid composition of the encephalitogenic polypeptide is exhibited.

Ultrastructural features of lipid vacuole formation in foam cells were studied in a mouse macrophage culture on the use of aggregated low density lipids (a-LDL) and fibroblast-modified LDL (fm-LDL). Modification of LDL properties is a factor which induces rapid transformation of macrophages to foam cells. Catabolism of a-LDL and fm-LDL and lipid vacuole formation is carried out in two ways: with and without involvement of lysosomes. In the former case membraneless lipid vacuoles are formed, in the latter one, lipid vacuoles surrounded by a membrane.

The role of high density lipoproteins (HDL), their subfractions (HDL2 and HDL3) and lecithin: cholesterol acyltransferase (LCAT) on peroxidative modification of low density lipoproteins (LDL) in vitro was studied. Peroxidative modification was estimated by the formation of malonic dialdehyde (MDA) and LDL aggregates during LDL incubation at 37 degrees C for several days without Fe2+ or for 2 hours in the presence of Fe2+ in EDTA-free media. It was shown that the addition of HDL3 (but not HDL2) markedly decreases the formation of both MDA and LDL aggregates. Since LCAT is bound to HDL3, its effect was examined. An addition of LCAT isolated from human plasma (650-fold purification) at a concentration of 450 micrograms/ml resulted in a complete inhibition of LDL peroxidation and LDL aggregate formation. Heat-inactivated LCAT had no effect. Possible mechanisms of the protective effect of LCAT on LDL peroxidative modification are discussed.

The hexokinase activity (HK) exceeded several times and the lactate dehydrogenase activity (LDH) was lower in soluble fraction of rabbit slow sceletal muscle as compared with fast sceletal muscle. In the soluble fraction of stomach smooth muscle the HK activity was higher and the LDH activity--lower than in slow sceletal muscle. The LDH isozyme spectrum of soduble fraction of smooth muscle was similar to the spectrum of slow muscle (mobile H-forms prevailed). Muscles of pyloric and fundal stomach parts differed in the enzymes activity and their isozyme content.

It has been shown that in the solution of low density lipoproteins (LDL) during their incubation at 37 degrees C the turbidity and concentration of malondialdehyde was increased, as compared to that observed at 4 degrees C. Both parameters were slowed down by the addition of high density lipoproteins (HDL) into the medium. The protective effect of HDL depended on the time of incubation and the concentration of HDL added. Delipidated HDL had no effect. Similar action of HDL was established in the experiments where the peroxidation in LDL was induced by the xanthine-xanthine oxidase. The data obtained demonstrate that HDL possess an antioxidant property that may play an important role in their antiatherogenic action.

An activity and isozyme spectrum of hexokinase were studied in rapid (gastrocnemius) and slow (soleus) muscles of rabbit in normal state and in experimental allergic polyneuritis, caused by administration of myelin from peripheric nerves mixed with Freund's stimulator. In normal organism the hexokinase activity was shown to be several times higher in soleus muscle than in gastrocnemius one. In these muscles the isozyme spectrum of the enzyme was markedly differentiated. In gastrocnemius muscle of rabbits with experimental allergic polyneuritis the hexokinase activity was distinctly increased due to increase in amount of the II type of the enzyme; in soleus muscle the decrease in the total activity of the enzyme depended upon the decrease in amount ofhexokinase II.

Decrease in the activity of hexokinase was found in soluble fraction of stomach smooth muscles of rabbits with alloxane diabetes. Administration of insulin into intact rabbits led to distinct decrease in the activity of lactate and malate dehydrogenases in cells of the stomach fundal part. In smooth muscles of rabbits with alloxane diabetes pyruvate was formed from lactate at a higher rate (increase in content of LDH1 and LDH2) and after administration of insulin into the animals--lactate was formed from pyruvate at an increased rate.

After administration of high doses of high density lipoproteins (HDL) into control rabbits the index of aorta permeability for 125I-low density lipoproteins (LDL) was decreased by about 19%. This index was decreased by 45% if HDL was administered into animals with hypercholesterolemia. Historadiographic assays showed that presence of 125I-LDL in circulation simultaneously with the exogenous HDL caused a decrease in the vessel wall permeability for LDL both in control rabbits and, especially, in hypercholesterolemic animals. As shown in experiments with human embryonal lung fibroblasts, under conditions of mainly unspecific interaction of LDL with cells, HDL inhibited the 125I-LDL absorption by 28%. High molar excess of HDL appears to inhibit the LDL penetration via intact endothelial layer into the arterial wall due to ability of HDL to compete with LDL at the sites of low affinity on the endothelial cells surface.

A study was made on the effect of high density lipoproteins (HDL) on the permeability of rabbit aorta to low density lipoproteins (LDL) after intravenous administration of human HDL and human [125I]LDL to normal and hypercholesterolemic rabbits. Evaluation of radioactivity in plasma and aorta has shown that the administration of a large dose of HDL decreased the aorta permeability rate for [125I]LDL on an average by 19% in normal rabbits, and by 45% in rabbits with moderate hypercholesterolemia. A historadiographic study showed that HDL also decreased the vessel wall permeability to [125I]LDL in normal and particularly in hypercholesterolemic animals. The suggestion was made that HDL at very high molar concentration can hamper LDL transportation through the intact endothelial layer into the intima due to the ability of HDL to compete with LDL in sites of low affinity on the surface of endothelial cells.

A basic low molecular protein, which caused development of experimental allergic polyneuritis in rabbits, was isolated from bovine sciatic nerves and purified by means of column chromatography.

The interaction of mouse peritoneal and human pericardial macrophages with lipoprotein (LP)-antibody (Ab) immune complex isolated from the serum of ischemic heart disease (IHD) patients has been studied. It is shown that the Ab of the autoimmune complex belongs to IgG class, and the antigen is the LP with d less than 1.063 g/ml. Incubation of mouse peritoneal macrophages with such complex led to the activation of [14C]oleic acid incorporation into cholesteryl esters by 2.5-2.8-fold, in comparison with the experiments where macrophages were incubated with free apoprotein (apo) B-containing LP isolated from the same serum. Incubation of human pericardial macrophages with autologous LP-Ab immune complex led to the transformation of macrophages into foam cells. These data lead to the conclusion that formation of LP-Ab autoimmune complexes may play an important role in the formation of atherosclerotic lesions of the arteries.

Activities of phosphorylase, hexokinase and pyruvate kinase were studied in soluble fraction of cells from dissimilarly acting sceletal muscles of intact rabbits and from those tissues with impaired neural impulsation (denervation, experimental allergic neuritis). Activity of phosphorylase was found to be 2.2-fold higher and of hexokinase--4-fold lower in soluble fraction of quick muscle as compared with that of slow muscle. Due to denervation these differences were smoothed off. The same alterations in hexokinase activity were observed in muscles of rabbits with experimental allergic neuritis both after impairment of sensitive innervation and after denervation.