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Biomedical subjects

A A Stavrovskaia

Publications and source records attributed to A A Stavrovskaia.

At least 19 recordsLinked to original sources
PubMed2001

[Functional activity and expression of P-glycoprotein in chronic myeloid leukemia].

AIM: To evaluate the prognostic significance of P-glycoprotein (Pgp) in chronic myeloid leukemia (CML). MATERIALS AND METHODS: Functional activity (rhodamine 123 test) and expression of Pgp (binding of UIC2 monoclonal antibodies by cells) were evaluated by flow cytofluorometry. A total of 141 samples of peripheral blood from 121 patients with various stages of CML were examined. RESULTS: The number of patients whose cells express functionally active Pgp increases during the blast crisis (BC) in comparison with the chronic phase (CP). Repeated testing of patients with BC and CP showed that Pgp-expressing cells can disappear from the peripheral blood of patients despite the treatment by Pgp preparations and substrates. However the number of cases with expression and functional activity of Pgp increases in the course of BC. Several patients in whom functionally active Pgp was not detected during diagnosis of BC had longer BC phase than patients with the active protein. CONCLUSION: These data suggest that active Pgp contributes to CML BC (presumably to patient's response to therapy) but this contribution is not decisive.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1995

[The clinical significance of the expression of the multiple-drug resistance protein P-glycoprotein in chronic myeloleukemia].

Cell resistance to pharmaceutical agents arises among other causes because of multiple drug resistance induced by P-glycoprotein (P-gp). The analysis of expression of P-gp and differentiation antigens of hemopoietic cells has been made on myeloid cells from 14 patients in CML chronic phase and 25 with CML acceleration and in blast crisis. Surface antigen expression was evaluated at flow cytofluorimetry (FACScan unit). Fluorescent dye rodomin (Rh123) helped examine P-gp functional activity. A close relationship is shown between P-gp expression and CD34 (r = 0.69. p = 0.0004), this giving evidence of these antigens expression on the same cells. In chronic phase P-gp is expressed on a few cells in some patients, its activity being low or absent. The appearance of UIC-2+ cells was unrelated to previous chemotherapy and brought no resistance to treatment. In terminal stage P-gp is expressed in 50% of cases. Functional tests identified the active protein in blast populations with a large number of UIC-2+ cells and in some patients with a small number of cells expressing P-gp. Therefore, comprehensive clinical investigations are needed of multiple drug resistance, though in half of the resistant patients in AML blast crisis P-gp+ cells were not identified suggesting the existence of other mechanisms responsible for resistance to treatment.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1991

[The normalization of tumor cell morphology related to an increase in their size: research on giant cells produced by mitomycin C treatment].

This study shows that artificial increase in cell site leads to morphological normalization of transformed fibroblasts. Mouse L cells (clone 171/5) were used. As most transformed cells, they were poorly spread on the substratum, made only dot-like focal contacts with it, rounded quickly at room temperature and did not contain prominent actin cables. Giant cells were obtained by incubation of these cells in the medium supplemented with mitomycin C (0.15-0.20 mcg/ml). DNA synthesis and mitosis were blocked by this treatment, while protein synthesis was changing very slightly. As a consequence, the cell size increased dramatically from 3 to 11 days of the cell incubation in the mitomycin containing medium. The degree of cell spreading per mcg of protein increased significantly in the giant cells. These cells do not round after moderate cooling, and well developed system of actin cables and matured streak-like focal contacts associated with these cables are formed in them. These results, along with our previous data on the restoration of cell spreading and cytoskeleton structure in giant multinucleated cells, provide strong evidences that the increase in cell size per se can induce qualitative changes in cell morphology. It can be suggested that there are some scaling-dependent factors regulating the processes of cytoskeleton assembly and formation of cell-substrate contacts.

Animals↗
PubMed1990

[The cells of murine sarcoma PC-103 induced by a polymeric plate secret transforming growth factor alpha].

It was shown previously that cells of sarcoma PS-103 induced in mouse by subcutaneous transplantation of plastic film produce growth-stimulating activity. In this communication clone 3 sb, isolated from sarcoma PS-103, was studied. Growth factor produced by the cells of this clone stimulated proliferation of quasi-normal (3T3, NRK) cells and transformed cells both in monolayer and in semi-solid medium. It was shown by gel filtration chromatography that the main growth-stimulating activity migrated with the protein fraction m.m. 10-15 kDa. The addition of this growth factor to the culture medium significantly (90%) inhibited 125I-EGF (epidermal growth factor) binding by A-431 cells. These data suggest that the growth factor produced by the studied tumor cells is transforming growth factor alpha.

Animals↗
PubMed1990

[Multiple drug resistance and differentiation in the population of transformed dog kidney cells MDCK].

Sublines of the canine kidney epithelium cells (MDCK) resistant to various colchicine doses (0.3-5.0 mcg.ml-1) were obtained by multistep selection. The new lines were shown to possess multidrug-resistance (MDR) by means of Rhodamine 123 staining. The initial steps of resistance (2 mcg.ml-1, 300-fold increase in resistance) are evidently due to enhancement of mdr gene transcription. Approximately 4-fold gene amplification was revealed in the cells resistant to 3 mcg.ml-1 of colchicine. All the drug-resistant lines tested were found to be more prone to differentiation than the wild type cells (both spontaneous and induced by several drugs such as DMSO, cAMP and others). The data suggest that the selection for overexpression of mdr gene results in selection of variants that are more capable of differentiation than the rest of the population.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1989

[Characteristics of crossed resistance of neoplastic cells with high level of colchicine resistance].

Using a long-term selection the authors obtained the cells of a hamster with a rather high level of stability to colchicine (800-16,600 times). The nature of resistance of these cells to actinomycin differed from those having general origin with the newly obtained but having a lower level of stability to colchicine. This level of stability did not correlate with that to a selective agent.

Animals↗
PubMed1989

[Effects of monoclonal antibodies to bovine nerve growth factor on NGF-induced cell differentiation in culture].

Five Hybridoma clones producing monoclonal antibodies (MAT) to bovine nerve growth factor (NGF) were developed. The biological effects of antibodies were studied: the influence of MAT on neurit outgrowth induced by NGF in rat pheochromocytoma PC12 or spinal chicken ganglia was investigated. MAT fell into two groups. Two of them inhibited neurit induction by NGF, three others stimulated this process. The stimulation of the neurit outgrowth by MAT was observed at low concentration of NGF (3 ng/ml of culture medium). Mechanisms of antibodies effects are discussed.

Animals↗
PubMed1986

[Clonal structure of tumors: difference between clones based on the ability to secrete growth-regulating factors and to react to them].

Conditioned medium isolated from different clones of tumour cell culture PS-103 (sarcoma induced in CBA mouse by plastic film implantation) varied in the ability to stimulate cell proliferation in semi-solid medium. The clones differed also in their response to the medium conditioned by culture PS-103: some clones responded by increased proliferation in semi-solid medium, some were inhibited and some failed to respond.

Animals↗
PubMed1984

[Relation between the attachment of cells to a substrate and their proliferative characteristics].

17 cloned cell lines of transformed mouse fibroblasts were used for the evaluation of a correlation between three traits of malignancy: cloning efficiency in semisolid medium (CE); cell dose inducing tumours in 50% of inoculated animals (TD50); degree of cell attachment to a substrate (RT50--rounding time for 50% of the cells under moderate cooling, 18 degrees C). It is shown that an increase in RT50 (better attachment of the cells to the substrate) is accompanied by a decrease in CE and an increase in TD50 (coefficients of rank correlation p = -0.76 and p = 0.58, respectively). A negative correlation between CE and TD50 was also revealed (p = -0.68). A certain increase in the percentage of cells containing actin filament bundles was found in cell clones better attached to the substrate. Mechanisms of disturbances in proliferation and attachment of malignant cells are discussed.

Animals↗
PubMed1984

[Independence from the substrate of multiplication in nonclonal and clonal tumor cell populations].

Experiments were made with sarcoma PS-103 cells cultured in vitro. The sarcoma was induced by implantation of a plastic plate into CBA mice. Clonal analysis of the cell culture demonstrated that 1) all 3 clones isolated from substrate (SB) grew in 1.2% methyl cellulose (MC) at the same efficiency as parental cells; 2) all 5 clones isolated from MC formed in a semi-solid medium 10-100-fold more colonies than PS-103. During the subcloning of one of PS-103 clones in solid substrate and in MC, it turned out that the majority of MC and SB subclones had the plating efficiency in MC similar to that in PS-103. Apparently, the PS-103 population contains clones with different degrees of anchorage independence.

Animals↗
PubMed1983

[Effect of polyploidization on the anchorage-independent multiplication of transformed cells].

Three nearhexaploid sublines were obtained from hypotriploid mouse L cells by means of colcemid treatment. When cultivated on solid substratum, all of them did not differ from the parental line either in doubling time or in cloning efficiency. The ability of polyploid cell variants to be initiated for proliferation in a semi-solid medium was equal to that of hypotriploid cells, while the average diameter of colonies formed by hexaploid cells in methyl cellulose turned out to be significantly smaller than the size of colonies of parental cells. The inhibition of growth in the semi-solid medium may reflect partial normalization of the transformed phenotype of polyploid L cells.

Animals↗
PubMed1982

[Gene mutation induction by the antitumor preparation ftorafur].

The influence of antitumor drug ftorafur (Ft) on the frequency of gene mutations to 8-azaguanine resistance was investigated. Asynchronous and synchronized cultures of SV40 transformed Djungarian hamster cells were used. The 2 to 3,5 fold increase in the frequency of gene mutations over the control level was observed after the Ft treatment. The most pronounced effect was obtained in the experiments with synchronized cultures, when exposed to Ft in the S-phase of the cell cycle.

Animals↗
PubMed1982

[Effect of ethylmethane sulfonate on the expression of one of the traits of malignancy by cultured mouse cells].

The influence of ethyl methane sulfonate (methane sulfonic acid ethyl esther, EMS) on anchorage independence of tumor cells was studied. Mouse near-diploid spontaneously transformed clonal fibroblasts (CAK-25Agr were used. They were characterized by a stable low cloning efficiency in 1,2% methyl cellulose ((3-5) . 10(-5) per cell seeded into a semi-solid medium). EMS enhanced the quantity of CAK-25Agr colonies grown in methyl cellulose. However, this enhancement was only obtained when correction on the cloning efficiency of the cells in a liquid medium was introduced. Subclones of CAK-25Agr isolated from methyl cellulose were studied for their ability to form colonies in the semi-solid medium. The number of subclones with elevated anchorage independence in cultures treated by a mutagen and in untreated cultures did not differ.

Animals↗
PubMed1982

[clonal analysis of the independence of tumor cell multiplication from the substrate].

The clone of near-diploid mouse transformed CAK-25AGr cells is characterized by the stable cloning efficiency in a semi-solid medium (about 10(-5) per cell plated in methylcellulose). It was shown that colonies in the semi-solid medium were formed by rare single cells and did not arise as a result of slow multiplication of all cells in the population. These cells are not genetical variants different from other cells in the culture. This is assumed on the basis of following data. First, the majority of the subclones arising in methylcellulose (9 of 12) retained parental cloning efficiency in the semi-solid medium. Second, all 6 subclones picked from the solid substratum had the ability to form colonies in methylcellulose with the frequency not lower than that of the parental clone. Apparently, the proliferation in methylcellulose of the transformed cells studied is a stochastic process. Each cell in the culture has the ability to initiate a colony in the semi-solid medium with the certain probability. This probability is a heritable characteristic of the cloned cell line. It is possible that this characteristic reflects the norm of reaction of the cells to some environmental factors.

Animals↗
PubMed1980

[Murine near-diploid cell clones: a model for the genetic analysis of signs of transformation].

Several near-diploid clones were obtained from the established mouse cell line, CAK-7. These clones proved to be highly oncogenic in syngeneic irradiated mice (TD50 = 1 x 10(2)--2 x 10(3). They differed in plating efficiency in semi-solid medium (from 5 x 10(-3) to 22 x 10(-5)). There was no correlation between tumorigenicity of the cells and their plating efficiency in methylcellulose. The differences between clones able to form anchorage-independent clonies would permit their use for the genetic analysis of this kind of malignancy.

Animals↗
PubMed1979

[Cell rounding in variant sublines of the L line caused by a moderate decrease in temperature].

Several novel variants of mouse transformed L cells are described. A distinctive trait of these variants, isolated by different methods, is a rounding of the majority of cells under the influence of the moderate cooling (at 18 degrees C for 30-60 min). In the serum-free medium, no rounding occurs. The rounding is presumably an active contraction, because it is inhibited by cytochalasin B. The comparison of the phenotype of wild-type and variant cells has shown that the exposure of cultures at 18 degrees leads to a disturbance of cell adhesion to the substratum in both the cell lines. The intensive rounding of variant cells at 18 degrees is due to some defect in their attachment to the substratum, which can be revealed not only at 18 degrees, but also at 37 degrees. By the selection procedure described in this paper, a large group of cell variants defective in adhesion to the substratum may be isolated.

Animals↗