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Biomedical subjects

I G Shcherbak

Publications and source records attributed to I G Shcherbak.

At least 19 recordsLinked to original sources
PubMed2000

[Characteristics of the acute phase reaction in humans with various types of autonomic nervous system regulation during simulated hyperthermia].

Depending on the type of autonomous regulation, differences in basic levels of interleukin-1 beta (IL-1 beta) and tumor necrosis factor alpha (TNF alpha) were revealed under conditions of hyperthermia in healthy subjects aged 19-21. A parasympathetic type of autonomous regulation corresponded to higher initial levels of proinflammatory cytokinesis, whereas a dominating sympathetic type corresponded to lower levels of the IL-1 beta and TNF alpha. The subjects with the latter type of regulation revealed an increase in the IL-1 beta TNF alpha combined with a higher heat tolerance. The subjects with the former type of regulation revealed a lower heat tolerance. The increase in the alpha2-macroglobulin appeared to be a most typical acute phase response of the human body to hyperthermia.

Acute-Phase Proteins↗
PubMed2000

[Hydrogen peroxide--a marker for respiratory tract inflammation in patients with bronchial asthma].

AIM: To test H2O2 as a marker of respiratory tract inflammation in patients with bronchial asthma (BA). MATERIAL AND METHODS: The study entered 70 patients (20 males and 50 females) with atopic asthma (AA) aged 18 to 62 years (mean age 32.6 years). H2O2 concentration in the expired air (CEA) was determined spectrophotometrically (Gallati & Pracht, 1985), content of eosinophilic cationic protein (ECP) in blood--with radioimmunoassay kits (Pharmacia & Upjohn, Sweden). Forced expiratory volume per 1 second (FEV1) was used for assessment of severity of bronchial obstruction. Bronchial hyperreactivity was studied by means of the histamine bronchoprovocative test. RESULTS: H2O2 in CEA in BA patients was higher than in healthy subjects (0.127 +/- 0.010 microm/l vs 0.024 +/- 0.004 microm/l). H2O2 concentration significantly correlates with FEV1 (r = -0.449; p < 0.001), bronchial hyperreactivity to histamine (rs = -0.382; p < 0.05) and ECP in blood plasma(r = 0.625; p < 0.01). CONCLUSION: It was proved possible to use H2O2 in CEA for evaluation of respiratory inflammation in BA patients.

Adolescent↗
PubMed1998

[Threshold mechanism of the control of cascade proteolysis].

The immune lysis rate of erythrocytes vs. the concentration of particular complement components was studied. It was found that in the presence of component C1 (but not C3) and factors B and D, the cells undergo lysis after the concentration of these compounds exceeds a "threshold" value. The threshold molar concentrations of factors D and B exceeded 5- and 20-fold, respectively, that of component C1. The multiplicity and different capacities of the thresholds allow the fragmentary activation of cascade proteolysis at stretches between neighboring thresholds without the total realization of the final effect of the system (cell lysis, clot formation, etc.). The resulting peptideby-products (bypass peptides) may possess their own biological activity. It is the generation of various bioregulators that appears to be the main function of the cascade proteolytic systems functioning in the subthreshold regime.

Animals↗
PubMed1995

[Structure and properties of extracellular proteins regulating the proteolytic phase of complement activation].

The structure and biochemical properties of the major soluble regulatory proteins of the complement, including the CI-inhibitor, factors I, H, and J, properdin, the C4-binding protein and other protein components, are reviewed. Three types of the proteolytic complement cascade regulation by proteins are envisaged: the first one involves the inhibition of complement proteases, the second one is based on proteolytic degradation of complement activation products and the third one includes the regulation of stability of complement protein complexes. The main functional role of humoral regulatory proteins consists in the limitation of the proteolytic cascade.

Complement Activation↗
PubMed1993

[Concentration-functional interrelationships in the human alternative complement activation pathway].

The dependence of the rate of human complement mediated lysis of rabbit erythrocytes on concentrations of factors B and D of the alternative pathway is characterized by saturation kinetics. At low B and D concentrations no lysis occurs until certain "threshold" concentrations of the respective factor are reached. The type of dependence of the hemolysis rates on the C3 concentration is wavelike, i.e., at definite C3 concentrations the erythrocyte lysis is inhibited. It has been supposed that C3 not only mediates the complement-dependent hemolysis but also plays a prominent role in the self-regulation of this process.

Animals↗
PubMed1992

Molecular heterogeneity of plasma superoxide dismutase.

A method was worked out that helped us to isolate superoxide dismutase (SOD) from human blood plasma. The change of enzyme's activity was shown depending on the period of SOD storage. Changes in activity were observed in storing protein after gel filtration. The activity of purified enzyme was half as much after 24 h storage and remained constant for a long period of time (5 mo). The change of SOD activity was found to be connected with a modification of its structure. The storage of enzyme's solution during 3 1/2 mo is accompanied by the lowering of protein molecular mass from 53,000 Da to 34,000 Da. The inhibitors of proteinases--phenyl-methylsulfonyl fluoride (PMSF) and alpha 2-macroglobulin--showed no protective effects on purified SOD. That's why it was possible to say that the lowering of protein molecular mass didn't connect with a specific proteolysis. An oxidative modification of SOD structure is under discussion now. The modification is most probably caused by oxidative destruction of aminoacid residues that are located outside the protein active centre.

Chromatography, Gel↗
PubMed1988

[Macrophage activation induced by a synthetic antioxidant].

The effect of a synthetic antioxidant 2-tretbutyl-3-hydroxypyridine (TBHP) on the function of murine peritoneal macrophages (MP) has been studied. A direct contact of TBHP with MP in vitro increased the activity of a key enzyme of glucose monophosphate graft--glucose-6-phosphate dehydrogenase and the proportion of flattened MP. as compared to the control. Upon intraperitoneal MP injection the number of MP's in the abdominal cavity of mice increased. They differed from control MP's in enhanced flattening and phagocytosis. In mice with preinduced defect of abdominal clearance TBHP contributed to the recovery of the normal level of antibacterial protection. In all the in vitro and in vivo tests studying its activating effect on MP, the synthetic antioxidant was not inferior to the standard MP activator--bacterial lipopolysaccharide.

Animals↗
PubMed1987

[Diagnostic value of determining endogenous proteinase inhibitors in cancer patients].

Patients with stage III and IV cancers of different sites revealed a 47-76% increase in serum total antitrypsinic activity. A mean 40% increase was observed in cases of inflammatory pathology. Both study groups demonstrated raised alpha 1-antitrypsin levels, while that of alpha 2-macroglobulin did not show any significant changes. The level of alpha 1-antitrypsin accounted for 89 and 83% of total antitrypsinic activity in cases of inflammation and controls, respectively, while in cancer patients this index was significantly lower (70%). The diagnostic value of total antitrypsinic activity appeared to be higher than that of alpha 1-antitrypsin level determination. It is inferred that, apart from alpha 1-antitrypsin, malignant growth is associated with raised levels of more specific endogenous proteinase inhibitors, except alpha 2-macroglobulin.

Clinical Enzyme Tests↗
PubMed1986

[Activation of glucose-6-phosphate dehydrogenase in mouse peritoneal macrophages by sera from patients with ischemic heart disease].

The purpose of this study was to compare the in vitro metabolic changes in mouse peritoneal macrophages exposed to sera of CHD patients and healthy donors. Oxidative (metabolic) burst was estimated by the activity of one of the limiting enzymes of hexose monophosphate shunt--glucoso-6-phosphate dehydrogenase. Pronounced enhancement of glucoso-6-phosphate dehydrogenase activity accompanied the exposure of macrophages to sera of patients with acute myocardial ischemia during the first two days after the onset of anginal pains. The correlation was established between the activity of creatine kinase in the sera of patients with acute myocardial infarction and the ability of these sera to enhance glucoso-6-phosphate dehydrogenase activity in mouse peritoneal macrophages.

Adult↗
PubMedDate not supplied

[Eznzymatic conversions of ortho-nitrophenyl organophosphorus compounds in the tissues of white rats].

In homogenates of rat tissues hydrolysis of O-heptyl-O-orthonitrophenylmethyl phosphonate, O-pentyl-O-orthonitrophenylmethyl phosphonate and O-heptyl-O-isopentyl-O-orthonitrophenylphosphate was studied. Hydrolysis of the preparation was shown to be carried out mainly in liver tissue and slso in kidney and blood serum. The substances studied were cleaved only at the bond P-O-aryl. The structure of orthonitrophenyl phosphoorganic substances exhibited the distinct effect on Km and on the maximal rates of the enzymatic hydrolysis. In all the tisses studied O-heptyl-O-orthonitrophenylmethyl phosphonate was hydrolyzed with maximal rate.

Animals↗
PubMedDate not supplied

[Turbidimetric analysis of fibrin polymerization in the plasma].

The turbidimetrical assay of thrombin-induced plasma coagulation provides a possibility to estimate both stages of fibrinogen-fibrin conversion. The initial one, which proceeds without any change of turbidity, reflects the process of protofibril formation, and the second stage of lateral aggregation, is characterized by the rise of turbidity. The influence of heparin, alga (Laminaria digitata) aqueons extracts, and collagenase on the indices of the turbidity-time curve has been studied. It was established that the alga extracts possessed the powerful heparin-like anticoagulant activity. The both agents influenced the first stage of the turbidity-time curve, suppressing protofibril formation, which reflects the thrombin inhibition. Nevertheless, they differed in their mode of dose-dependence. While the time of protofibril formation was direct proportional to the alga extract concentration, it was rising more intensively with heparin dose elevation. Plasma pre incubation with alga extract or heparin did not influence their action. Treatment with plasma collagenase changed only the second stage of the coagulation curve. It inhibited the process of protofibril lateral aggregation in the direct proportional manner. It must be due to fibrin digestion by the enzyme. We propose that fibrin cleavage by collagenase occurred out of the thrombin action sites, because the velocity of protofibril accumulation stayed unchanged. Our data illustrate the usefulness of the turbidimetrical analysis in the studies of the agents' action mechanisms on blood coagulation, in conditions close to physiological ones.

Blood Coagulation↗
PubMedDate not supplied

[The action of karbogal on the complement system under model conditions and in an animal experiment].

The influence of dimethylperfluorocyclohexane (carbogal) on the hemolytic activity of human blood serum complement was studied in vitro. It has been show that different effects of carbogol on the complement depend on the serum lipid composition. Endotracheal administration of carbogal to rats results in a significant reduction of complement activity in the animal's blood. Significant changes in the hemolytic activity of the complement recorded 21 days after the endotracheal administration of the compound are, probably, associated with the complement depletion after its activation by carbogal particles or with disorders in the complement component synthesis by macrophages.

Animals↗
PubMedDate not supplied

[Antitrypsin effects of alpha-2-macroglobulin].

Purified preparations of alpha 2-macroglobulin were preincubated with bovine trypsin at various molar ratios. Effects of the preincubation were measured before and after addition of soybean trypsin inhibitor in excess if N-benz-L-arg-p-nitroanilide was used as a substrate. Two types of interaction between alpha 2-macroglobulin and trypsin were detected. One of them was carried out depending on the "trap" hypothesis, another type of the interaction led to the enzyme loss of both proteolytic activity and its ability to hydrolyze the low molecular substrate. The data obtained suggest that various molecular forms of native alpha 2-macroglobulin were responsible for these types of interaction.

Animals↗