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Biomedical subjects

A M Ishchenko

Publications and source records attributed to A M Ishchenko.

At least 19 recordsLinked to original sources
PubMed2002

[Non-specific changes in the complement system in neoplastic processes].

The study using immunochemical and biological methods was concerned with assaying complement components C1q, C3, C4, and C5, C3 derivatives--C3a and, C3(H2O), C1ing control protein, hemolytic activity (CH50), total proteolytic activity and regulatory immune complexes in sera from patients with cancer of the stomach, breast and ovary, subjects at risk of cancer and healthy donors. Neoplasia was associated with lowered levels of intact C3 and C1ing matched by high concentrations of C3a, C1q and C4. Hemolytic activity (CH50) was increased against the background of relatively higher total proteolytic activity both in healthy subjects and cancer patients. Significant decrease in C1ing concentration may be used as an additional biochemical prognosticator in breast cancer.

Biomarkers, Tumor↗
PubMed1998

[Activation of astrocytes of by anaphylatoxins of the complement system].

It has been shown that astrocytes (human glioblastoma U118 cell line) release reactive oxygen species (ROS), including superoxide O2.- and hydrogen peroxide H2O2 following the action of C5a complement component C5a (but not C3a). The effect of C5a (1 nM) is accompanied with hyperpolarization of the astrocyte plasma membrane. Component C3a (100 nM), which is not an inducer of ROS, caused a prolonged depolarization of astrocytes. However, both the agents induced a transient increase in intracellular Ca2+ concentration. The data obtained permit a conclusion that O2.- participates in the intracellular signal transduction, and is involved in the mechanism of hyperpolarization response of astrocytes to the effect of the inducer of ROS, complement component C5a.

Astrocytes↗
PubMed1998

[Mechanisms of hyperpolarization of plasma membrane of macrophages and astrocytes during activation].

The hyperpolarization response of macrophages and glial cells (astrocytes, U118 cell line) to the action of inducers of reactive oxygen species (ROS) has been studied. Macrophages were stimulated with chemotactic peptide fMLP and platelet activation factor (PAF). Astrocytes were affected by complement component--anaphylatoxin C5a. The hyperpolarization response of both cell types depends on intracellular Ca2+ concentration and extracellular K+ concentration. Depletion of K+ concentration in the medium (1 mM KCl) or chelation of intracellular Ca2+ with Quin-2 (50 microM) significantly decreased the hyperpolarization response or caused depolarization of plasma membrane. Moreover, inhibition of Ca(2+)-dependent K(+)-channels with quinidine (50 microM) induced only a prolonged depolarization of both cell types. The data obtained permit a suggestion that macrophage and astrocyte hyperpolarization response to stimulation with ROS inducers involves O2.- mediated activation of Ca(2+)-dependent K(+)-channels.

Animals↗
PubMed1996

[Levels of complement components in plasma of onco-hematologic patients with defective hemopoiesis].

Immunochemical assay using monoclonal antibodies was carried out to determine levels of a number of complement components (C3 and its derivatives-C4 and C5) and immunoglobulins (lg) in plasma of patients with onco-hematological diseases involving defective hemopoiesis: leukemia, myelodysplastic syndrome (clonal diseases) or aplastic anemia (delayed clonal disease). The most significant disorders were registered in the concentrations of component C3 and its derivatives. In acute leukemia, the nature and extent of C3 splitting was found to depend on disease while Ig level-on stage. Myelodisplasia usually involved a 2-3-fold decrease in C3 level matched by a rise in the concentrations of its derivatives-C3-like form and C3a fragment. Reduced C3 levels matched by increased ones of Ig were observed in some cases of aplastic anemia. It is suggested that disturbances in complement component level may cause changes in cascade reactions of the complement in onco-hematological patients and thus indirectly influence immune response regulation processes.

Complement C3↗
PubMed1994

[Conformational analysis and hemolytic activity of immunoglobulin G fragment 285-292 and its analogs].

Theoretical conformational analysis was carried out for the 285-292 fragment of human immunoglobulin G (His-Asn-Ala-Lys-Thr-Lys-Pro-Arg) and its analogues containing Arg, Glu, Gly, Lys, or Trp residue instead of the His residue in position 1. Spectropolarimetic investigation of these peptides showed the analogues to have different activities in the C1q-mediated erythrocytes hemolysis assay. Comparison of the low-energy structures sets of the compounds tested allowed to suggest a model of the "biological active" conformation for the peptide molecule in the course of the C1q complement component binding.

Complement C1q↗
PubMed1989

[Level of the C3-component of complement in the blood serum of sick children].

The levels of the complement C3 component have been measured in children with various diseases (immunodeficiency states, food allergy, rheumatoid arthritis, severe and medium-severe forms of acute respiratory viral infections), and the complement consumption in the course of alternative activation has been examined. The findings evidence a relationship between the complement C3 component consumption and the blood serum IgA level, as well as between the C3 level and the neutrophilic phagocytic and metabolic activities.

Arthritis, Rheumatoid↗
PubMed1987

[Peptidoglycan isolated from Lactobacillus bulgaricus: its effect, mediated by the complement system, on pre-T-cell maturation].

Peptidoglycan from Lactobacillus bulgaricus converts mouse pre-T-cells into theta-positive cells and activates the complement. It has been observed that the effect depends on serum peptidoglycan concentration and the time of the interaction of the activated complement with mouse pre-T-cells. The action of peptidoglycan was replaced by C3a complement component.

Animals↗
PubMed1987

[Effect of SOS repair in enterobacteria on their interaction with the complement system].

The interaction of E. coli (serovar 0124) and its rec A-mutants with serum complement resulting in the alternative pathway activation was studied. Bacteria VT1240 (original smooth strain), VT1241 (rough mutant) and VT 2240 (recA56 mutant) were shown to be complement-sensitive when treated with 1.5 X 10(8)--1.9 X 10(8) cells per ml of normal human serum, while the cells with SOS-activated system (recA441 mutant, strain VT3251) retained their viability. An alternative pathway of complement activation was minimal with E. coli VT1241, while VT3251 demonstrated intermediate activity. To decrease the level of complement components (AH50) and factor B (BH50) by 50%, 3.5 X 10(6)--4.5 X 10(6) cells of VT1240 and VT2240 strains were required. R-mutants and recA441 mutants caused a 50% reduction in AH50, when used in the amount of 6.4 X 10(7) and 2.6 X 10(7), respectively, the same degree of BH50 decrease was achieved with the amounts used equal to 1.1 X 10(8) and 4.3 X 10(6), respectively. C3 conversions caused by 4 X 10(8) cells in I ml of the normal human serum in the four strains tested accounted for 5-15%.

Complement Pathway, Alternative↗
PubMed1983

[A mechanism of human complement activation by immunostimulators from the bacterial cell wall].

Effects on the human complement system of the cell wall preparations: lipopolysaccharides and polysaccharides of E. coli, Salmonella typhi (pyrogenal, salmosan), Bact. prodigiosum (prodigiosan) and peptidoglycan of Lactobacillus bulgaricus (blastolysin) have been studied. Lipopolysaccharide of E. coli, pyrogenal and salmosan were found to bind efficiently the first complement factor C1q. The constants for inhibition of the C1q binding to antibodies by the mentioned preparations were determined, and their ability to initiate the classical pathway of complement activation (consumption of C4, C2 and C3 factors) was assayed. These preparations only slightly affect the alternative pathway. Prodigiosan, not influencing the classical pathway, initiates the alternative one. Its binding constant with the activated Bb factor was determined. This constant reflects the Bb association with C3b and is (2,4 +/- 0,1) x 10(7) mole-1 l. Blastolysin is effective both in the C1q binding and initiation of the alternative pathway of complement activation. Immunostimulating activity of the bacterial cell wall preparations seems to involve activation of the complement system and the release of the fragments from the complement factors which are mediators of the immune response.

Anti-Bacterial Agents↗
PubMed1978

[Molecular parameters of sensitization of tannin-treated erythrocytes with Salmonella d-flagellin].

A study was made of the molecular parameters of sensitization of tannin-treated sheep red blood cells with salmonella d-flagellin, depending on the protein dose, exposure, and temperature of the medium; the role played in this process by physical and chemical mechanisms was ascertained, the latter proving to determine the hemosensitization level. Senstivity of the erythrocytic diagnostic agent to the agglutinating action of the specific serum was maximal with a stable binding by a single red blood cell of about 200 000 flagellin molecules, although the limit of stable binding constituted 340 000 molecules per one red blood cell. On condition of saturation limit of the erythrocyte flagellin should block not over half of the cell surface. The temperature elevation during the diagnostic agent preparation is advantageous in technological respect, since it leads to reduction of flagellin expenditure and increases the sensitivity of the passive hemagglutination tests.

Animals↗
PubMed1975

[Characteristics of the hydrodynamic and biological properties of flagellar preparations isolated from submerged cultures of S. typhi].

A study was made of the hydrodynamic and biological properties of the flagella from the S. typhi 4446 cultures, isolated by the methods of differential centrifugation, in crude condition and following depolimerization and denaturing by the action of chemical and physical agents. Molecular parameters of the slow and rapid components of the flagella and subunits of the flagellin were compared. The greatest antigenic activity was possessed by the high molecular fraction of the flagella isolated in the 60% sucrose density gradient.

Animals↗