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Biomedical subjects

Iu B Vakhtin

Publications and source records attributed to Iu B Vakhtin.

At least 19 recordsLinked to original sources
PubMed1994

[Pathological mitoses in clones of the RA-2 subline of rat transplantable rhabdomyosarcoma selected for increased and decreased frequencies of the formation of spontaneous micronuclei].

Cell substrains with increased and decreased spontaneous levels of micronuclei have been obtained by artificial selection. Clones of the substrains were investigated for mitotic division fidelity. About 200 mitoses were investigated in each clone. Frequencies of mitotic abnormalities such as ana- and telophases with bridge, chromosome and fragment delays at ana- and telophases, scattered chromosomes, chromosomes dislocated from spindle at metaphases and tripolar ana- and telophases were significantly higher in substrains with increased level of micronuclei. This finding indicates that reasons for arising of spontaneous micronuclei and alterations in mitotic division fidelity are the same or closely related. These reasons can be amplified as a result of the artificial selection.

Animals↗
PubMed1992

[Interclonal and interpopulational differences in the frequency of spontaneous karyotypic changes in cell populations of transplantable rat rhabdomyosarcoma RA-2].

Rat organospecific transplantable RA-2 rhabdomyosarcoma substrains RA-2H (high metastatic potential), RA-2L (low metastatic potential) and RA-2T (thermal resistance) were investigated using single cell cloning technique for frequency of micronucleated cells (FMC). Significant interclonal and interpopulational differences were established. Average FMC for RA-2H was 2.96 +/- 0.13%; 5.94 +/- 0.24% for RA-2L and 1.89 +/- 0.12% for RA-2T. Clones showed 5-10 times differences in FMC in each substrain. FMC versus growth time and clone size was studied in RA-2H: average FMC dropped from 2.7% on day 9 to 0.5% on day 20 after administration and the lowest values were recorded in larger clones at each stage. Perspectives of FMC studies in tumor cell populations are discussed.

Animals↗
PubMed1992

[The dependence of the incidence of encountering cells with micronuclei in the experimental metastases of rat rhabdomyosarcoma on the duration of the growth and on the size of these metastases].

Cell suspensions of rat transplantable rhabdomyosarcoma RA-2 were injected to white rats. The experimentally induced lung metastases (ELM) were estimated according to the frequency of micronucleated cells (MNC) that appeared 9-20 days after injection (a. i.). The frequency of MNC in ELM decreased from 2.7% (9 days a. i.) to 0.7% (20 days a. i.). The ELM which were of the same size but were examined at different time after injection had equal frequencies of MNC. At each investigated time after injection the least frequencies of MNC were observed in the ELV of the biggest size. The data provided allow to infer that the growth time and site of ELM may influence the spontaneous karyotype instability rates.

Animals↗
PubMed1992

[Changes in the frequency of cells with micronuclei in cell populations of rat transplantable rhabdomyosarcoma RA-2 as a result of selection for an increased and a decreased frequency of such cells].

Artificial selection for increasing and decreasing frequencies of cells with micronuclei (FCM) was conducted in populations of cell clones of the rat transplantable RA-2 rabdomyosarcoma. The selection was effective in both the opposite directions. The average FCM increased from 3.3 +/- 0.2 to 6.9 +/- 0.6% and decreased from 3.3 +/- 0.2 to 1.6 +/- 0.2%. Heritability coefficient, h2, varied from 0.2 to 0.4. In the cell population with increased FCM, 37% of anaphases and early telophases had lagged chromosomes and fragments. In contrast, in the cell population with decreased FCM, lagging were observed in 11% of cases. The DNA-content in G1 cell varied greatly in cell population with increased FCM (P < 0.01). The selection for increased FCM has led to a significant decrease in metastatic capacities of cells.

Animals↗
PubMed1990

[Clonal analysis of karyotypic instability and metastatic potential in tumor cell populations].

Rat organospecific transplantable RA-2 rhabdomyosarcoma strains RA-2H and RA-2L were investigated using single cell cloning technique for "Micronuclear containing cell frequency" (MCF) and "Metastatic potential" (MP). The RA-2H was obtained from RA-2 during selection for increasing metastatic potential, whereas the RA-2L was the result of selection in opposite direction. MP was assessed by lung colony formation technique and in the case of RA-2H, it was one hundred times greater than in the case of RA-2L (2490 +/- 280 and 22 +/- 11 lung colonies i.v. after injection of 10 cells, respectively). Average MCE for RA-2H was 3 and for RA-2L 5.3%. Also, significant differences were observed between these substrains in percentage of anaphase and telophase cells with bridges and fragments (24 +/- 4 for RA-2H and 56 +/- 5% for RA-2L, P less than 0.05). The selection of RA-2H clones with high level of MCF was successful. In the population obtained MCF was increased up to 7.8% and MP decreased (79 +/- 44). So, the selection for decreasing of MP led to significant increase in genome instability characteristics and the selection for increasing of MCF--to the abrupt decline of MP, which proved the existence of negative correlation between these two characters in populations studied. It is concluded that correlation between malignancy and genome instability in tumor populations with different levels of malignancy is not, as a rule, positive.

Animals↗
PubMed1989

[Artificial selection for increased metastatic potential in cell population of transplanted rhabdomyosarcoma RA-2 in rats].

The rhabdomyosarcoma was induced with 20-methylcholanthrene in unbred white rat; it was selected for the metastatic potential (MP)--the ability to form experimental lung metastasis after i. v. injection of tumor cells. After 10-15 cycles of selection there was 100-fold increase in the level of MP, all the tumor cells acquired simultaneously the affinity to the lung tissue. After that the tempo of selection decreased. From 112-124 to 177-183 cycles of selection the frequencies of MP-cells in the population were increased only 10-fold (from 0.007 to 0.06). High level of karyotypic and phenotypic heterogeneity persisted in the selected cell population, the differences for MP between clones were great. It was shown the heritable instability of the character "the MP-level" in the selected cell population.

Animals↗
PubMed1989

[Changes in primary heat sensitivity of rhabdomyosarcoma PA-2 cells in rats during selection for heat resistance].

Using the technique of multistep selection, a thermoresistant substrain (TR RA-2T45) was obtained from a rhabdomyosarcoma RA-2 strain. The cells of this substrain retain the ability to form lung metastasis after a 20 minute treatment at 45 degrees C in vitro. The selection of cells for their ability to retain their reproduction activity is accompanied by the increase in their primary thermoresistance. The increased reproductive thermoresistance and primary thermoresistance of the selected cells is hereditary stabilized. Cells of both original strain and its substrain are capable of thermal tolerance, which makes perspective the selection for further increase in thermoresistance in RA-2T4t cell population.

Animals↗
PubMed1988

[Selection for a decrease in metastatic potential in a cell population of transplantable rat rhabdomyosarcoma RA-2].

The method of individual cloning was used for checking the reduction of metastatic potential (MP) in cell population of highly malignant rhabdomyosarcoma RA-2. In the course of 15 selection cycles MP was lowered by 10-15 times. These data enabled us to consider the MP value as a quantitative character of malignant cells with low heritability (the mean value of realized heritability coefficient is equal to 0.18).

Animals↗
PubMed1985

[Variation in the number of C-heterochromatin blocks in the interphase nuclei of the cells of a transplantable murine rhabdomyosarcoma].

By means of staining procedure which reveals the constitutive heterochromatin (CH), the number of CH-blocks was detected in the nuclei of interphase cells obtained from the subcutaneously growing rhabdomyosarcoma and from its 10 lung colonies. The range of variability of the number of CH-blocks in tumor cell populations was greater than in the populations of normal lung cells and lymphocytes. The mean numbers of CH-blocks varied from 17.8 +/- 0.9 to 28.0 +/- 1.2 in cells of different clones, the mean number of CH-blocks in clones being the same as in the subcutaneously growing uncloned tumor. The coefficient of heritability h2 of character "the number of CH-blocks", calculated on the basis of population and interclonal variances, was equal to 0.15, and that calculated by one-factor dispersional analysis was actually the same (0.16). It is concluded that the high heterogeneity of tumor cells may be conditioned not only by their high phenotypic instability, but also by a high frequency of mutations.

Animals↗
PubMed1985

[Isozymes of NADP-dependent isocitrate dehydrogenase in normal and tumor tissues of various mouse strains and their hybrids].

Normal tissues of DBA, CBA, CC57W, C3H, Balb/c, SHR mice and F1 hybrids CC57W/DBA appeared to differ in the ratios of mitochondrial and supernatant NADP-dependent isocitrate dehydrogenase (IDH). Tested inbred mice strains CC57W, C3H, SHR, Balb/c contain allelic form Idh-1a of supernatant IDH gene Idh-1, whereas allelic form Idh-1b is characteristic of mice strains DBA and CBA. In tumors IDH isozymes have the same mobility as do isozymes of homologous normal tissues; but their activity is lower. A high variability of each isozyme activity in the isozyme spectrum is revealed in various tissues of F1 hybrids CC57W/DBA. Allelic forms of gene Idh-1 were used as markers of normal and tumor cells for the experimental model: transplantation of sarcoma 37 (Idh-1a/Idh-1a) to subcutaneous tissue of the mouse strain DBA (Idh-1b/Idh-1b). It enables us to reveal isozymes of stromal cell in tumor IDH isozyme spectrum. The results indicate that the relation of normal and tumor isozymes vary in different tumors.

Alleles↗
PubMed1985

[Sarcolysine sensitivity of the progeny of the clonogenic cells of rat rhabdomyosarcoma RA-2].

Cells of rat rhabdomyosarcoma Ra-2 inoculated intravenously were trapped only in lungs and formed progressively growing monoclonal metastases. The population of clones was sensitive to the sarcolysin treatment (10-30 mg/kg) at all stages of clone formations (from 1 to 14 days). The drug acted by two ways: by the reduction of the number of clones and by the clone growth rate inhibition. Independent variability of both types of the clone sensitivity resulted in the highly heterogeneous response of clone populations to the sarcolysin treatment.

Animals↗
PubMed1984

[Genome mutation frequency in the cells of spleen colonies of different origins in NIH mice].

Genome mutation frequencies (GMF) were determined in cells of endogenous (from bone marrow) and exogenous (from bone marrow, spleen and embryonic liver) spleen colonies on the basis of variations in DNA contents of interphase nuclei. In cells of the former GMF varied from 1.1 X 10(-2) to 10.8 X 10(-2), and in the latter these were equal to 8.9 X 10(-2). In the cells of exogenous colonies derived from X-irradiated precursors (1.8 and 5.9 Gy) GMF were 10.1 X 10(-2) and 11.9 X 10(-2), resp. The mode of transplantation influenced greatly on the GMF: after an additional short transplantation (4-6 days) the number of GMF increased by 1.5-2 times. It is concluded that the increased number of GMF may be responsible for the limited life-span of bone marrow stem cells in the course of their serial transplantations in the irradiated syngenic mice.

Animals↗
PubMed1983

[Intraclonal and interclonal differences of ploidy in transplantable rat rhabdomyosarcoma RA-2 detected using DNA flow cytometry].

DNA contents were determined using flow cytometry in cells of 71 clones of the rat transplantable rhabdomyosarcoma passed through more than 70 cycles of selection for increased malignancy. 58 clones (82%) consisted of cells with diploid DNA content, whereas 13 clones (18%) displayed not only diploid, but also near tetraploid cell subpopulations, the latter covering from 20 to 60% of the total number of cells measured. The data obtained show the existence of intra- and interclonal karyotypic heterogeneity in populations of tumor clonogenic cells.

Animals↗
PubMed1981

[Changes in the LDH isoenzyme spectrum in transplantable rhabdomyosarcoma clones transplanted into the anterior chamber of the eye].

Results of gel electrophoresis of transplantable rat (RA-2) and murine (MC-53) rhabdomyosarcomas show that the LDH isoenzyme spectrum of tumors growing subcutaneously differ from that of normal muscle tissue, LDH-1 and LDH-2 isoenzyme being absent in zymograms. Using the lung colony formation technique, clones of RA-2 and MC-53 were obtained and their zymograms were investigated. Clone populations of both the tumors were polymorphic for their LDH spectrum, in some clones of RA-2 normal LDH isoenzyme spectrum was found. After a 16-18 day cultivation in rat and mouse eye anterior chamber, LDH spectra of RA-2 and MC-53 clones changed sharply, LDH-1 and LDH-2 appearing. As a result, LDH isoenzyme spectra of some clones that grew in the eye anterior chamber became equal to those of the normal muscle tissue. The observed changes are discussed as biochemical signs of cytodifferentiation of tumor cells.

Animals↗