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Biomedical subjects

M E Preobrazhenskaia

Publications and source records attributed to M E Preobrazhenskaia.

At least 19 recordsLinked to original sources
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↗
PubMed1991

[Neutral alpha-D-mannosidase activity in human granulocytes].

The presence of neutral soluble alpha-D-mannosidase activity was shown in human granulocytes. For detection of the enzyme different methods were used: addition of stabilizing agents; sorption of acid alpha-D-mannosidase on concanavalin A-sepharose; inhibition of acid alpha-D-mannosidase; determination of neutral alpha-D-mannosidase in granulocytes of patients with inherited defect of acid alpha-D-mannosidase (mannosidosis). The specific activity of neutral alpha-D-mannosidase in granulocytes of donors calculated in nmol/min/mg of protein was near to the activity in lymphocytes. However the activity in granulocytes calculated in nmol/min/10(8) of cells was approximately 3 times lower than that in lymphocytes. The activity of neutral alpha-D-mannosidase in immature myeloid cells of a patient with chronic myeloid leukaemia was 10 times higher than in natural granulocytes of the same patient. This high activity may be in connection with the process of cell differentiation or the result of malignant transformation.

Granulocytes↗
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↗
PubMed1985

[Acid glycosidases of normal cattle lymphocytes and in chronic lympholeukemia].

The activity of five acid glycosidases was determined in lymphocytes from normal animals and animals with chronic lymphocytic leukemia. It was shown that alpha-D-mannosidase activity in leukemic lymphocytes was 5 times lower (p less than less than 0.001) and alpha-D-glucosidase activity was 2 times lower (p less than 0.01) than in normal controls. The progress of the disease and the increase in leukocyte count were accompanied by the decrease in alpha-D-mannosidase activity. No differences have been found in alpha-D-mannosidase properties (thermostability, Km values, ZnSl2 activation) in normal and leukemic lymphocytes.

Animals↗
PubMed1977

[Characterization of dextranase from Penicillium purpurogenum (Ftoll)].

An extracellular dextranase (E. C. 3.2.1.11) was purified from cell-free culture filtrates of Penicillium purpurogenum (Ftoll). The enzyme was most active at pH 5,5. The dextranase was endo-type, it split quickly isomaltotetraose into two isomaltose molecules, slowly degraded isomaltotriose, and did not act on isomaltose. The rate of isomaltooligosaccharides hydrolysis was increased with the increase of the polymerization degree. Polyols obtained from isomaltooligosaccharides were split more slowly than the respective sugars. The isomaltopentaitol was split at two glucosidic linkages, 38% of hydrolyzed linkages being the second linkage from the sorbitol end of the molecule and 62% being the third one. The degree of degradation of dextrans depended on amount of 1,6 linkages. Isomaltose and tetrasaccharides of two types, 2(2)-alpha-D-glucosylmaltotriose and linear tetrasaccharide(s), are the lowest molecular weight products of exhaustive hydrolysis of branched dextrans.

Culture Media↗
PubMedDate not supplied

[Lymphoid cell glycosidases in various forms of lymphoproliferative disorders].

Activity of 8 glycosidases (6 acid lysosomal and 2 neutral cytosolic enzymes) was estimated in lymphoid cells of 28 patients with different forms of lymphoproliferative disorders: B- and T-chronic lymphocytic leukemia (CLL), non-Hodgkins lymphoma (NHL), Sezary syndrome, hairy cell leukemia (HCL) and B- and T-acute lymphoblastic leukemia (ALL). Activity of these glycosidases was also studied in mononuclear cells and granulocytes of healthy volunteers and in immature myeloid cells of 16 patients with chronic myeloid leukemia (CML). In lymphoid cells of all the patients studied (except of ALL) the glycosidases activity was decreased as compared with that of normal mononuclear cells and immature myeloid cells. Activity of the majority enzymes studied was higher in T-lymphoid cells of patients with lymphoproliferative disorders as compared with B-cells. The highest glycosidases activity was found in ALL cells and the lowest--in CLL cells of the patients with B-lymphoid cells forms of the disease. Activities of N-acetyl-beta-D-hexosaminidase, alpha-D-mannosidase and beta-D-glucuronidase were distinctly dissimilar in cells of the patients with B-CLL, B-NHL and HCL. Estimation of these glycosidases activity in lymphoid cells may be of importance in differential diagnosis of lymphoproliferative disorders.

Biomarkers, Tumor↗
PubMedDate not supplied

[Dextran glucosidase activity of the acid alpha-glucosidase from pig spleen].

Some properties of acid alpha-glucosidase from pig spleen are studied. Changes in the enzyme activity with respect to polymeric and oligomeric substrates were shown to take place under effects of temperature, pH, concentration of metal ions, urea treatment, trehalose inhibition. Dextran and glycogen were used as polymeric substrates, and disaccharides with different types of bonds were taken as oligomeric substrates. The data obtained confirm the hypothesis on separate regions of binding polymers and oligomers with the enzyme molecule.

Animals↗
PubMedDate not supplied

[Acid glycosidases in leukocytes of patients with chronic and acute myeloid leukemias].

Activities of five acid glycosidases were examined in leukocytes of 30 healthy persons, 17 patients with chronic myeloid leukemia (CML) and 7 patients with acute myeloid leukemia (AML). In leukocytes of the patients with CML activities of alpha-D-mannosidase, N-acetyl-beta-D-hexosaminidase and beta-D-glucurodase were significantly higher (p less than 0.01) and those of alpha-D-galactosidase and alpha-D-glucosidase were somewhat higher (p less than 0.05) as compared with control leukocytes. Activities of all five glycosidases in leukocytes of patients with AML were within the normal limits. Glycosidase activities were also examined in leukocytes of three groups of patients with CML at different stages of the disease: chronic, progressive and blast crisis. All the enrymes exhibited the highest activity in the first group of patients; the activities of these enxymes in the second group were lower and those in the third group were close to normal. When CML leukocytes were fractionated using the Ficoll-verografin method, the activities of the enzymes in the interface fraction (unmatured cells) were higher than those in the bottom fraction (matured granulyocytes). These data suggest that the increased glycosidase activity in CML cells is due to the presence of the population of unmatured granulocytes which are distinct from blast cells.

Clinical Enzyme Tests↗