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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
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↗
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

[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↗
PubMedDate not supplied

[The effect of plasmin on complement in human blood serum].

Plasma exhibited the dose-dependent inactivating effect on human blood serum hemolytic complement both in classic and alternative pathways. Negative correlation (r = -0.8) was found between the rate of complement inactivation and content of C3 component. Plasmin appears to hydrolyze mainly the C3 component of complement as a result of which hemolytic activity of complement is decreased.

Blood↗
PubMedDate not supplied

[Endogenous inhibitor of cysteine proteases from the human kidney].

A thermo- and acid stable inhibitor of cysteine proteinases was isolated from the human kidney by successive procedures--acid fractionation, gel-filtration on Sephadex G-75, affinity chromatography on papain-sepharose. The final purification factor was 650 fold. The inhibitor molecular weight was equal to 12 kDa. The values of Ki measured by different methods are (7.9-9.4) X 10(-4) M for papain and (7.1-8.0) X 10(-10) M for purified human kidney cathepsin B. In experiments with papain, inhibitor kass and kd were 1.1 X 10(6) M-1 s-1 and 9.0 X 10(-4) s-1, respectively. The inhibitor did not influence the trypsin activity, its properties being similar to those of related thermo- and acid-stable inhibitors from other human and animal tissues.

Chromatography, Gel↗
PubMedDate not supplied

[Activity of cathepsin B and serine trypsin-like peptide hydrolases in human kidney extracts].

A potentiality to use the available substrates BAPNA and BAME was studied in estimation of activities of cathepsin B and other trypsin-like hydrolases in extracts of human kidney cortex. In these extracts the BAME-hydrolyzing activity of cathepsin B was difficult if impossible to detect due to high level of attendant non-thiol esterases. At the same time, BAPNA might be used for this purpose as a substrate in estimation of cathepsin B- and trypsin-like peptide hydrolase activities in biopsies of human kidney.

Benzoylarginine-2-Naphthylamide↗
PubMedDate not supplied

[Products of the proteolytic effect of cathepsin on various protein substrates].

Cathepsin B was shown to hydrolyze in calf thymus histones not only the peptide bonds involving alkaline amino acid residues but also the bonds involving aromatic amino acid residues. Thermo- and acid stable inhibitors of cysteine proteinases were found among the products of albumin hydrolysis by means of these enzymes as well as in the products of the enzymes autolysis.

Animals↗