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Biomedical subjects

N A Ushakova

Publications and source records attributed to N A Ushakova.

At least 19 recordsLinked to original sources
PubMed2006

The role of beta1 integrin subfamily in anchorage-dependent apoptosis of breast carcinoma cells differing in multidrug resistance.

Integrin expression was investigated in MCF-7 human breast adenocarcinoma line and in the MCF-7Dox line, which was selected from MCF-7 by a resistance to multiple antitumor drugs (MDR). We have shown that acquisition of MDR was accompanied by a drastically reduced expression of some integrins of the beta1-subfamily (alpha2beta1, alpha3beta1, alpha6beta1) and of alpha vbeta5 intergin in the adenocarcinoma cells. In contrast, expression of alpha5beta1 integrin was markedly increased in the MDR cells. Along with multiple antitumor drug resistance, MCF-7Dox cells demonstrate elevated resistance to anchorage-dependent apoptosis (anoikis) and enhanced in vitro invasive activity. To elucidate the implication of beta1-integrins in the above phenotypic modifications, the effect of beta1-integrin signaling was assayed. Stimulation of beta1-mediated signaling was accomplished by treating of the cells with antibodies to the beta1-subunit common for members of the beta1-subfamily. These data show that activation of beta1-integrin signaling markedly upregulated anoikis of the adenocarcinoma cells.

Anoikis↗
PubMed2005

Monomeric and multimeric blockers of selectins: comparison of in vitro and in vivo activity.

The potency of the oligosaccharides SiaLe(x), SiaLe(a), HSO(3)Le(x), and HSO(3)Le(a), their conjugates with polyacrylamide (PAA, 40 kD), and other monomeric and polymeric selectin inhibitors has been compared with that of the polysaccharide fucoidan. The following assay systems were used: 1) a 96-well assay based either on the use of recombinant E-, P-, and L-selectins or an analogous assay with natural P-selectin isolated from human platelets; 2) a platelet-based P-selectin cell assay; and 3) a rat model of peritoneal inflammation. IC(50) values for the neoglycoconjugate SiaLe(a)-PAA were 6, 40, and 85 microM for recombinant E-, P-, and L-selectins, respectively; all monomeric inhibitors were about two orders of magnitude weaker. PAA-conjugates, containing as a ligand tyrosine-O-sulfate (sTyr) in addition to one of the sialylated oligosaccharides, were the most potent synthetic blockers in vitro. Compared with fucoidan, the most potent known P- and L-selectin blocker, the bi-ligand glycoconjugate HSO(3)Le(a)-PAA-sTyr displayed similar inhibitory activity in vitro towards L-selectin and about ten times lower activity towards P-selectin. All of the tested synthetic polymers displayed a similar ability to inhibit neutrophil extravasation in the peritonitis model (in vivo) at 10 mg/kg. The data provide evidence that monomeric SiaLe(x) is considerably more effective as a selectin blocker in vivo than in vitro, whereas the opposite is true for fucoidan and the bi-ligand neoglycoconjugate HSO(3)Le(a)-PAA-sTyr.

Acrylic Resins↗
PubMed2004

Uncharged P-selectin blockers.

The blocking potency of P- and L-selectin was studied for certain small molecule mannosides and their polyacrylamide (PAA, 30 kDa) conjugates in comparison to SiaLe(x) and fucoidan. Two experimental systems were used: (1) solid phase static assay based on recombinant selectins, and (2) P-selectin dependent rat peritoneal inflammation. betaMan-SC6H4NO2- p was four times more potent P-selectin inhibitor as compared to SiaLe(x). Docking of this molecule onto the P-selectin carbohydrate-binding site demonstrated that a nitro group enabled an electrostatic interaction with residue Lys 84, while the phenyl ring and the CH2 at C-6 contacted the CH2 groups of the same Lys residue. In vivo, betaMan-SC6H4NO2- p blocked experimental inflammation better than SiaLe(x), but significantly lower than fucoidan. In vitro Man-polyacrylic acid conjugates appeared to be very potent inhibitors comparable to fucoidan, uncharged Man-PAA proved rather active, comparable to SiaLe(x)-PAA both in vitro, and in vivo, whereas mannan did not display any P-selectin blocking effect.

Acrylic Resins↗
PubMed1999

Adaptation to salt stress in a salt-tolerant strain of the yeast Yarrowia lipolytica.

We have studied the cellular mechanisms underlying adaptation to salt stress in a newly isolated osmo- and salt-tolerant strain of the yeast Yarrowia lipolytica. When cells are incubated in the presence of 9% NaCl, a rapid change in their size and shape is observed. Salt stress is accompanied by an increase in the intracellular level of glycerol, free amino acids (notably proline and aliphatic amino acids), and Na+, as well as by changes in lipid and fatty acid composition.

Atriplex↗
PubMed1997

Fucoidan inhibits leukocyte recruitment in a model peritoneal inflammation in rat and blocks interaction of P-selectin with its carbohydrate ligand.

Neutrophil recruitment into systemic inflammatory sites in vivo is thought to be initiated by selectin-mediated endothelial adherence. The effect of fucoidan (natural sulfated polymer of L-fucose) on the selectin dependent PMN migration into rat peritoneum following the induction of inflammation by peptone injection was studied. Peritonitis was characterized by an increase in the total cell number (from 45.3 x 10(6) to 91.6 x 10(6)/rat), and by highly elevated PMN content (from 0.2% to 58%) in the rat peritoneal cavity 3 h after peptone injection. Intravenous administration of fucoidan was found to reduce, in a dose-dependent manner, neutrophil migration into peritoneum. Fucoidan in a dose as low as 0.8 mg per rat caused 96.8% reduction of neutrophil extravasation. The inhibitory effect of fucoidan was also dependent on the time intervals between the peptone and fucoidan injections. The maximal inhibitory effect of fucoidan was observed within the first 15 min after the induction of peritonitis and it was maintained at a level of 80% during 1.5 h. Administration of fucoidan 2.5 h after peptone injection had practically no effect on PMN extravasation. Since P-selectin is known to play a key role at the earlier stages of PMN extravasation, it was suggested that the inhibitory effect of fucoidan was mostly due to its interaction with P-selectin. The in vitro experiments demonstrated the high affinity of fucoidan for both isolated P-selectin and P-selectin in plasma membranes of activated platelets.

Animals↗
PubMed1995

Lysosomal glycosidases in different populations of human thymocytes.

Lysosomal glycosidase activities were studied in human thymocyte fractions obtained by two methods: (A) fractionation in Percoll density gradient and (B) separation from the cells forming rosettes with sheep erythrocytes (E-RFC). (A) affords fraction L, enriched with immature and endogenously activated thymocytes, and fraction H containing mature thymocytes. By use of (B), fraction E-RFC--enriched with non-activated immature thymocytes--was obtained. Comparative study of E-RFC and H revealed diverse alterations in activities of glycosidases during thymocytes maturation, specifically decreases in alpha-L-fucosidase and alpha-D-mannosidase and an increase in beta-D-galactosidase. Comparing E-RFC and L demonstrates increases in activities of studied glycosidases following endogenous activation of thymocytes.

Adjuvants, Immunologic↗
PubMed1994

Isoform patterns of lysosomal glycosidases in phenotypically different leukemic lymphoid cells.

Isoform patterns of six lysosomal glycosidases were studied in leukemic lymphoid cells phenotypically related to B and T cells at distinct stages of differentiation. In all types of cells, the activity of glycosidases under study was expressed in two major isoforms. No correlation was observed between isoform patterns and cell phenotypes. The beta-hexosaminidase isoform ratios for phenotypically related leukemic lymphoid cells but isolated from different sources (blood and spleen) differed. It was suggested that cell localization affects isoform expression. An anomalous alpha-mannosidase was detected in lymphoid cells from lymph nodes, while it was lacking in the phenotypically related blood lymphoid cells from the same patients. Isoform I of beta-hexosaminidase was recorded in lymphoid cells of patients with anemias.

Anemia↗
PubMed1992

Acidic alpha-D-mannosidase in phenotypically different leukemic lymphoid cells.

The activity of acid alpha-mannosidase in phenotypically characterized lymphoid cells, isolated from peripheral blood, spleen and lymph nodes of patients with various lymphoproliferative disorders has been studied. Cells with different immunophenotypes were shown to have different alpha-mannosidase activity levels. The lowest alpha-mannosidase activity was observed in cells phenotypically corresponding to early B cells obtained from B-CLL patients. The highest activity was determined in cells with phenotypes of activated, CD11c-expressing B cells from B-NHL and HCL patients. There were considerable differences in alpha-mannosidase activity between peripheral blood and spleen lymphoid cells of B-NHL patients with spleen damage. The data obtained may be used in classification, primary diagnosis and staging of hematopoietic malignancies.

Humans↗
PubMed1991

Activity of some proteinases and glycosidases in human leukemic lymphoid cells at various stages of differentiation.

Activities of some glycosidases and proteinases in human leukemic lymphoid cells at various stages of differentiation have been compared. It was found that cells with different immunological phenotypes gave different enzymic spectra. Glycosidases and proteinases in lymphoid cell precursors had higher activity level than the enzymes in mature T- and B- cells. In cells of B- lineage, all activities were lower than in common precursor of lymphoid cells. In T-cells at the earlier stages of thymic differentiation, activities of all proteinases and most of glycosidases were higher than in common precursor cells whereas in mature T-helpers and T-suppressors the activities were markedly lower. Most of hydrolases in mature T-cells were twice more active than the enzymes in mature B-cells. The opposite-directional changes in activities of some hydrolases at the earlier stages of differentiation of lymphoid cells along B- or T- cells pathways are suggested.

Antigens, Differentiation↗
PubMed1991

[Neutral alpha-mannosidase in human B- and T-lymphoid cells].

The presence of neutral alpha-mannosidase activity in normal and pathological lymphoid cells has been demonstrated. The specific activities of the enzyme in different cell types were similar with the exception of B-cells from B-CLL patients when it was a little higher. The activity of acid alpha-mannosidase was also determined in these lymphoid cells. The neutral to acid alpha-mannosidase activity ratio was different in B- and T-cells: in the former neutral alpha-mannosidase activity prevailed, whereas in the latter the predominance of acid alpha-mannosidase activity was apparent. Neutral alpha-mannosidases from pathological B- and T-cells were partially purified and their properties were investigated. In both cell types the enzyme was localized in the cytosol, was very labile and could be stabilized with Mn2+ and dithiothreitol. The enzyme was activated by Co2+ and inhibited by Zn2+ and EDTA. Swainsonine inhibited the B-cell neutral alpha-mannosidase somewhat more strongly in comparison with the T-cell enzyme.

B-Lymphocytes↗
PubMed1991

[Glycosidase activity in phenotypically different pathologic lymphoid cells, found at various stages of differentiation].

The activities of seven glycosidases (six lysosomal and one cytosolic) were determined in B- and T-lymphoid cells differing by immunological phenotypes and occurring at various differentiation stages. The cells were isolated from the circulating blood, bone marrow or spleens of patients with various forms of lymphoproliferative disorders. The glycosidase activities varied significantly depending on the phenotype. The highest activity of all glycosidases was observed in cells with a common lymphoid cell progenitor phenotype. In cells having the phenotype of mature T- and B-cells the glycosidase activities were comparatively low. The changes in all glycosidase activities depending on the phenotype and differentiation stage usually occurred in the same direction; however, the degree of elevation or decline of activities of individual glycosidases was different. The activities of N-acetyl-beta-D-hexosaminidase and alpha-D-mannosidase changed dramatically, whereas the changes in the activity of cytosolic neutral alpha-D-glucosidase were less apparent. These data suggest that lysosomal glycosidases play specific roles in lymphoid cell differentiation.

B-Lymphocytes↗
PubMed1988

[Acid alpha-D-mannosidase of human leukocytes in the norm and during chronic myeloid leukemia].

The activity and properties of acid alpha-mannosidase were studied in normal granulocytes and in two types of myeloid cells from patients with chronic myeloid leukemia. The activity of the enzyme in leukemic cells was 2-fold higher than that in normal granulocytes and in morphologically matured myeloid cells. Two latter types of cells did not differ in alpha-mannosidase activity. Kinetic properties, thermo- and pH stability of alpha-mannosidase from normal and leukemic cells were similar. alpha-mannosidase in leukemic and normal cells existed in two forms (A and B), which were easily separated on DEAE-cellulose column. These two forms differed in molecular mass (300 and 290 kD, respectively) and in the degree of sialylation. The quantitative ratios of A and B forms in normal and leukemic cells were different. In normal granulocytes and in mature cells from patients this ratio was 0.60 and 0.67, respectively. In leukemic cells the ratio was found to be 1.31. Thus, in leukemic cells form A of alpha-mannosidase predominanted, whereas in normal cells the predominance of form B was observed. It was suggested therefore that in leukemic cells the enhanced synthesis of alpha-mannosidase occurred in parallel with the accumulation of the B form. This accumulation was assumed as the cause of enhanced activity of the enzyme in immature leukemic cells.

Humans↗
PubMed1983

[Soluble and membrane-bound neutral alpha-glucosidase from the human kidney].

In human kidney cortex neutral alpha-glucosidases 1 and 2 are represented by two forms, soluble (cytosolic) and membrane-bound (brush border) ones. It has been shown that the soluble enzyme preexists in human kidney but does not derive from the membrane-bound form. Similar to the membrane-bound enzyme the soluble form is a glycoprotein. Both enzyme forms possess identical electrophoretic mobility, pH-optimum, heat sensibility and Km values for maltose (0.7 mM) and 4-methylumbelliferyl-alpha-D-glucopyranoside (0.57 mM), but differ by molecular weights as determined by gel filtration chromatography. The molecular weights of the soluble neutral alpha-glucosidases 1 and 2 are lower than those of the comparable brush border enzymes (470 000, 360 000, 520 000 and 440 000, correspondingly). Neutral membrane-bound alpha-glucosidase 1 is a sialylated enzyme with a pI of 4.10 +/- 0.02. The soluble enzyme contains no or only traces of neuraminic acid and has a pI 4.40 +/- 0.03. The soluble and membrane-bound neutral alpha-glucosidases are apparently independent forms of the enzyme, differing by the degree of sialylation and by the presence of an "anchor" in the membrane-bound enzyme. The synthesis of both forms is presumably coded by the same structural gene.

Cell Membrane↗