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Biomedical subjects

A M Amchenkova

Publications and source records attributed to A M Amchenkova.

At least 19 recordsLinked to original sources
PubMed1997

Two pathways of the nitric oxide-induced cytotoxycal action.

Nitric oxide is a diffusible messenger with multiple biological functions. We show here that NO-generating compound, S-nitrosoglutathione (GSNO) induces apoptosis in human chondrocytes and causes necrosis-like cell death in human epithelial CaOv cell line. Pretreatment of chondrocytes with low-dose GSNO or with gamma-interferon enhances their tolerance to the second high-concentration GSNO exposure. On the contrary, in CaOv cells low-dose GSNO pretreatment diminishes the resistance and increases cytolysis at the second GSNO exposure. We conclude that human chondrocytes possess specific and inducible mechanism preventing cell killing by nitric oxide.

Apoptosis↗
PubMed1996

Alternative processing of the tryptophanyl-tRNA synthetase mRNA from interferon-treated human cells.

We have analysed the structure of mRNA isoforms of the human gene encoding tryptophanyl-tRNA synthetase (Trp-tRNA synthetase) expressed in the epithelial CaOv cells and MT-4 lymphocytes. The Trp-tRNA synthetase gene is induced by interferon-gamma in both lines and, in MT-4 lymphocytes, also by interferon-alpha. Four Trp-tRNA synthetase mRNA isoforms have different combinations of the first exons IA, IB and II. Two transcription initiation sites (P1 and P2) were detected 90 bp from each other. Processing of the primary transcript initiated from the P1 start site generates the mRNA isoform where exon IA joins to exon II. The other three isoforms are produced by alternative splicing of the primary transcript produced from the P2 start site. Isoform 2 has a 3'-end fragment of exon IA joined to exon II. Isoform 3 contains exons IA and IB. Isoform 4 contains exon IA and exon III and lacks exon II encoding the N-terminus of the Trp-tRNA synthetase. Therefore, the two primary transcripts of the Trp-tRNA synthetase gene differ only in the 5' flank sequence between P1 and P2, and this fragment regulates their processing. Both interferon-alpha and interferon-gamma induce exon IA-containing and exon IB-containing isoforms of the Trp-tRNA synthetase mRNA.

Alternative Splicing↗
PubMed1991

[An interferon inhibitor in regulating the activity of human natural killer cells].

The action of mouse serum interferon--alpha/beta (IFN) at the dose of 100 U/ml, of its inhibitor (I) at the dose of 8 U/ml as well as of their combination with the above doses on sensitivities of mouse target cells (TC) of sensitive to IFN line L 929 and resistant to the one line MCB in natural cytotoxic reaction was studied. Cytotoxic activity of human natural killer cells was detected in 14 hrs cytotoxic test using 3H-uridine for labelling of TC. IFN, I, and IFN+I were added to cell cultures for 24 hrs at 37 degrees C with following removing of preparations. It has been shown that I abolished protective effect of IFN on TC L 929 whereas the one possessed the protective action on TC MCB in natural cytotoxic reaction. These data confirmed a suggestion about immunoregulatory properties of I which displayed in abolition or realization of protective effect on TC in natural cytotoxic reaction in dependence on initial sensitivity of TC to antiviral IFN action.

Animals↗
PubMed1990

[Activity of human natural killer cells against target cells possessing different sensitivity to interferon].

The cytotoxic activity of peripheral blood natural killers (NK) against target cells (TC) J-96 and L-929 with high sensitivity to interferon (IFN) action, J-41 and MCB resistant to IFN action and line K-562 labelled by H3-uridine was studied in 14 hrs cytotoxic test. It has been shown that human TC J-96 didn't differ from the J-41 in their sensitivity to NK cytotoxicity and they are strongly resistant to NK than TC K-562. The murine TC L-929 as the human TC didn't differ from the MCB in their sensitivity to NK lysis and had also the same sensitivity to NK as the K-562 cells.

Animals↗
PubMed1989

[Interferon-specific cellular receptors in cultured human cells, differing in sensitivity to alpha-interferon].

The interferon-specific cellular receptors in human cells cultures differing in sensitivity to alpha-interferon have been studied. The J-41 cells resistant to alpha-interferon are practically devoid of receptors highly specific to alpha-interferon. The coefficient of equilibrium and the number of receptors analyzed after Scatchard for J-96 culture of cells are 15.6 x 10(11) M-1 and 210 +/- 90, respectively. Evidently, resistance of J-41 cells to alpha-interferon is connected with the absence of interferon receptors and, as a consequence, inability to interferon-receptor interaction.

Cells, Cultured↗
PubMed1988

[Induction of interferon-specific enzymes in cultures of cells sensitive and resistant to interferon].

Induction of 2'-5'-oligoadenylatesynthetase (2-5A synthetase) by interferons and theophylline by means of activation of cAMP-system in interferon susceptible and resistant cell lines were studied. In interferon resistant cell lines the basal activity of 2-5A synthetase exceeded the level of the same enzyme in interferon susceptible cell lines. Activity of 2-5A synthetase is increased in interferon susceptible cell lines by interferon treatment, but the activity of the enzyme is not altered in interferon resistant cell lines. Among the studied cell lines the induction of 2-5A synthetase by theophylline was possible only in L929 cell line. The common mechanism for the absence of 2-5A synthetase induction by interferon and theophylline in interferon resistant cells is discussed.

2',5'-Oligoadenylate Synthetase↗
PubMed1984

[Ratio of the antiproliferative action of interferon to the degree of purity of the preparation].

The antiproliferative (AP) action of human leukocytic interferon (HLI) of varying degrees of purification was studied and compared in cultures of human cells differing in interferon sensitivity. The concentrated and purified preparations of HLI suppressed the incorporation of 3H-thymidine and mitotic activities of the cultures sensitive to HLI of the cells, affecting, but insignificantly, the proliferation of the resistant cell culture. Poorly purified HLI suppressed the proliferation of both cell types. This indicates that native HLI contains impurities that have an AP action and exerts no antiviral activity.

Cell Division↗
PubMed1981

Comparative cytogenetic study of a continuous human cell line and its subline susceptible and resistant, respectively, to coxsackie B3 virus.

Cytogenetic characteristics of the J-96 human cell line and its J-41 subline, highly susceptible and resistant, respectively, to coxsackie B3 virus, were compared. The J-41 subline, as compared to the original J-96 line, had fewer chromosomes in the modal class cells (54-57 and 58-62, respectively) mostly at the expense of normal chromosomes. In most J-41 cells chromosome 21 was eliminated and the number of homologues of chromosomes 2, 9, 11, and 12 was reduced. The percentage of marker chromosomes in the J-41 subline (31.3) was slightly higher than in the J-96 line (24.3). The relationship between differences in the karyotypes and properties of the cultures such as resistance to coxsackie B3 virus, capacity to produce virus-induced interferon and to acquire an antiviral state after treatment with interferon were discussed.

Cell Line↗
PubMed1981

[Evaluation of the toxic effects of preventive and therapeutic preparations in transplantable cell cultures from different species and of different origins. I. Demonstration of the toxic properties of commercial batches of adsorbed DPT vaccine in cell cultures].

Continuous cell cultures are sensitive test systems used not only for the determination of the toxicity of diphtheria exotoxin, but also for revealing the toxic properties of adsorbed DPT vaccine. Morphological changes induced by the action of diphtheria exotoxin and adsorbed DPT vaccine in the cultures of L929, HeLa, FL, L132 and monkey tonsil cells are similar in character. The effect produced by the diphtheria exotoxin and adsorbed DPT vaccine on cell cultures may be characterized as toxic, subtoxic and minimal. Nevertheless, even in the cultures treated with minimal concentrations the pathological state of the cells can be detected in the next 2 or 3 serial subcultures.

Amnion↗
PubMed1980

[Heterochromatinic segments in chromosomes of cultured human cells, sensitive and resistant to Coxsackie B viruses].

Comparative karyological studies of C-heterochromatin have been made on line J-96 of human cells, which are susceptible to enteroviruses, and on cell line J-41 derived from this culture and possessing highly specific resistance to Coxsackie B viruses. It was shown that the development of specific resistance to Coxsackie B viruses was accompanied by the loss of one of the chromosomes of pairs 1 and 9, and by the dissapearance of two marker chromosomes. There appeared new marker chromosomes with additional C-heterochromatain regions. The data obtained are discussed with respect to a possible interrelationship between these chromosomal alterations and the specific resistance to Coxsakie B viruses.

Cell Line↗
PubMed1978

[Relationship between group G chromosomes, especially chromosome 21, and the sensitivity of human cells to Coxsackie B viruses].

The R-method of differential chromosome staining by length was applied to comparative karyological studies on the culture of J 96 human cells susceptible to enteroviruses, and on the J 41 cell line derived from this culture and possessing high specific resistance to Coxsackie B viruses. Karyotype of the J 41 cell line was shown to be deprived of chromosome G21 (P less than 0.0001). The number of other chromosomes varied from cell to cell, but they are constantly present in the majority of cells of both the J 96 and J 41 cell lines. A conclusion is drawn that chromosome G21 incorporates gene(s) which controls the human cells susceptibility to Coxsackie B viruses.

Cell Line↗
PubMed1978

[Formation of heterosymplasts in human reticular cell cultures].

The cell fusion has been studied in human reticular cell cultures J-96 and J-41 treated with the Sendai virus or with polyethylene glycol 1000 and 6000. The J-96 cells have a high alkaline phosphatase activity, in J-41 cells the enzyme is not detectable. No heterogenous alkaline phosphatase activity was seen in the protoplasm of symplasts 18 hours after virus cell fusion. It has been shown with polyethylene glycol treatment that during the fusion of cells J-96 and J-41 the enzyme activity was spreading over the symplast protoplasm.

Alkaline Phosphatase↗