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Biomedical subjects

M Tálas

Publications and source records attributed to M Tálas.

At least 19 recordsLinked to original sources
PubMed1985

Interferon production by and radioprotective effect of poly I : C and tilorone in mice exposed to helium alpha irradiation.

Serum interferon production induced by poly I : C and tilorone and their radioprotective effect in mice exposed to He-alpha particles was studied. The results were compared to those observed after exposure of mice to acute 60Co-gamma irradiation. Interferon production induced by poly I : C was depressed by He-alpha irradiation less than that induced by tilorone. Treatment of mice with poly I : C or tilorone before He-alpha irradiation had no effect on the mortality of animals in contrast to the radioprotective activity of these compounds against 60Co-gamma irradiation.

Alpha Particles↗
PubMed1983

Effect of glutaurine on liver tumour development and acute leukaemia induced by MC29 virus in turkey poults.

The effect of glutaurine (gamma-L-glutamyl-taurine, Litoralon) on the take and development of hepatoma and acute leukaemia induced by MC29/L avian oncorna-virus has been investigated in turkey poults. Glutaurine significantly decreased the incidence of hepatoma, but had no significant effect on the lethality of MC29/L infected birds. The number of primitive myeloid cells was lower in the peripheral blood of glutaurine treated birds than in the untreated controls. Reverse transcriptase determinations in turkey fibroblast cell cultures indicated that glutaurine delays MC29/L virus expression.

Animals↗
PubMed1983

Results of space experiment program "Interferon". I. Production of interferon in vitro by human lymphocytes aboard space laboratory Solyut-6 ("Interferon I") and influence of space flight on lymphocyte functions of cosmonauts ("Interferon III").

The results of the biological space experiment "Interferon" performed by two international cosmonaut crews aboard the space laboratory Solyut-6 are reported. Human lymphocytes separated from the blood of healthy donors and placed into "Interferon I" equipment could be kept for 7 days in suspension culture under spaceflight conditions. Interferon production could be induced in human lymphocytes by preparations of different origin, such as virus, synthetic polyribonucleotides, bacterial protein and plant pigment. An increased lymphocyte interferon production was observed in the space laboratory as compared to the ground control. A decrease of induced interferon production and natural killer cell activity was observed in the cosmonauts' lymphocytes on the 1st day on Earth after 7 days spaceflight.

Cell Membrane Permeability↗
PubMed1983

Results of space experiment program "Interferon". II. Influence of spaceflight conditions on the activity of interferon preparations and interferon inducers ("Interferon II").

The influence of spaceflight conditions on the biological activity of HuIFN-alpha preparations (lyophilized, in solution and in ointment) and interferon inducers was studied. In antiviral activity no difference was observed between the samples kept aboard the spaceship and the controls kept under ground conditions. The interferon inducers poly I:C, poly G:C and gossipol placed in the space laboratory for 7 days maintained their interferon-inducing capacity. The circulating interferon level in mice was the same irrespective of the induction being performed with flight or ground-control samples of inducers.

Animals↗
PubMed1982

Lack of correlation between impaired interferon production and natural killer activity of lymphocytes in multiple sclerosis.

The ability of lymphocytes from patients with multiple sclerosis (MS) to produce Interferon (IFN-alpha) in response to Newcastle Disease Virus (NDV) was studied in vitro. The correlation between individual IFN-alpha titers and natural killer (NK) cell activity and the presence of HLA system antigens associated with MS (B-7 and DRW-2) was also investigated. Lymphocytes from MS patients showed a significantly impaired capacity to synthesize IFN-alpha in vitro when compared to lymphocytes from healthy donors (mean titers: 85.9 I.U. and 268.2 I.U., respectively). Marked differences in IFN-alpha titers were observed in the group of MS patients. The production of IFN-alpha by the patients' lymphocytes did not correlate with either the activity of NK cells or with their stimulation by exogenous IFN-alpha. There was also no correlation between IFN-alpha production by lymphocytes from MS patients and the presence or absence of B-7 and DRW-2 antigens.

Adolescent↗
PubMed1982

Association between HLA B7, DR2 and dysfunction of natural- and antibody-mediated cytotoxicity without connection with the deficient interferon production in multiple sclerosis.

In this study, 133 patients with MS were investigated for HLA-A,B,C,DR antigens, natural killer (NK) cell activity, and antibody-mediated cytotoxicity (ADCC). A higher frequency of HLA B7 and DR2 was found in this group of patients than in the healthy control group, as can be observed in other caucasoid populations as well. In Gypsies living in the same geographic area, almost a complete absence of the disease was observed, corresponding to a lack of B7; however, HLA DR2 was present in 56% of this population. NK activity and ADCC measured against the K-562 tumor cell line was found to be significantly lower in MS patients, most pronounced in the group of male patients. Interferon augmentation of NK activity showed similar impairment in the patient group, and their lymphocytes produced a significantly lower amount of interferon. A correlation was demonstrated between both killer cell function and HLA B7, DR2 in MS patients, however, it was significant only in the case of ADCC and DR2. No other correlations were found in relation to interferon augmentation, interferon production, and HLA antigens. The above finding underscores a possible HLA-linked pathogenetic role of NK and K cell dysfunction in MS. This is consistent with other, similar observations that a possible defect in virus immunity may exist in MS patients.

Adult↗
PubMed1981

In vivo selection of two agents differing in hepatoma-inducing activity from strain MC29 avian leukosis virus.

MC29 virus induces acute leukemia (myelocytomatosis) and primary tumors of liver (hepatomas) in turkey poults. By in vivo passages two viruses were selected; designated "liver" and "bone marrow" variants, differing in hepatoma-inducing activity. The "liver" variant induces hepatoma and acute leukemia, the "bone marrow" variant induces acute leukemia. The variants differ in leukemogenic activity. The "bone marrow" variant induces high grade leukocytosis, while the "liver" variant causes lymphocytosis and heteropenia. The variants also induce the appearance of primitive myeloid cells in the blood. The kinetics of accumulation of viral gs protein (p27) and the presence of viruses inducing hepatoma and leukemia were studied in organs of infected turkeys. The differences between the variants showed no relationship with their selective reproduction capacity in liver and/or bone marrow cells. The results obtained suggest that different viral particles are responsible for the induction of leukemia and hepatoma.

Animals↗
PubMed1981

Proliferation inhibition of murine pluripotent haemopoietic stem cells by interferon or poly I:C.

The effect of mouse serum interferon (IF) in vitro and an inducer in vivo on the proliferation of a pluripotent stem cell population with high turnover rate was studied. Proliferation rate was characterized by the number of CFUs in the S phase of the cell cycle. Increased proliferation of bone marrow stem cell populations was produced either by irradiating the donor mice with 3.36 Gy (336 rad) 60Co-gamma rays 7 days before the experiment or by incubating normal bone marrow cells with 10(-11) M concentration of isoproterenol. IF considerably reduced the number of CFUs in S phase in both cases without reducing the CFUs content of the samples. Injection of IF inducer (4 mg/kg poly I:C) into regenerating mice also inhibited the proliferation of CFUs without decreasing the femoral CFUs level. Regeneration kinetics of CFUs from irradiated poly I:C-treated mice ran parallel with that of irradiated untreated animals but showed a characteristic delay corresponding to approximately one CFUs doubling. A transient, non-cytotoxic proliferation inhibitory effect of IF or IF inducer is, therefore, proposed.

Animals↗
PubMed1980

Dysfunction of natural killer cells in multiple sclerosis: a possible pathogenetic factor.

Natural killer (NK) cell activity, antibody-dependent cytotoxicity (ADCC) and the effect of interferon on NK activity was investigated in multiple sclerosis (MS) patients. NK activity measured against K-562 tumour cell line was found to be significantly low in MS patients, and this was most pronounced in the group of male patients with definitive disease. The response of NK cells to interferon proved to be impaired and almost no activation could be demonstrated in response to polyinosinic-polycytidylic acid (poly I:C). Preliminary data obtained by the determination of interferon production in several definitive MS cases reflect a defect in the interferon producing capacity of lymphocytes. The possible involvement of impaired NK cell function in the aetiopathogenesis of MS is discussed.

Adult↗
PubMed1979

Type I interferon induced in mice by infection with Trypanosoma equiperdum.

Type II interferon is known to be produced in mice infected with Trypanosoma cruzi. Therefore, interferon production was investigated in mice infected with Trypanosoma equiperdum. Interferon was found in the sera of mice infected with T. equiperdum from day 1 after infection until death on day 5. The maximal level of interferon appeared before parasitemia was detected, a finding showing that the endogenous interferon probably had no significant influence on the course of infection. Unexpectedly, the serum interferon was characterized as type I by its stability at pH 2 and by its neutralization by antiserum to virus-induced mouse interferon. The production of two different types of interferon in mice infected with T. cruzi and T. equiperdum may have been due to the dissimilar life cycles of the two trypanosomes in the white mouse.

Animals↗
PubMed1979

Induction of interferon and radioprotective activity of polyriboguanylic-polyribocytidylic acid complex in mice.

The effect of polyriboguanylic-polyribocytidylic acid complex was investigated against acute X- and prolonged 60Co-gamma irradiation. Prophylactic administration of the polyribonucleotide complex increased endogenous spleen colony formation and the percentage of survival of irradiated BALB/c mice. The most pronounced effect was observed when the animals had been irradiated at the time of maximum interferon accumulation in blood, i.e. 24 hr after interferon induction by the polyribonucleotide complex.

Animals↗
PubMed1978

Radioprotective activity of interferon inducers.

The radioprotective activity of interferon inducers (tilorone, Acranil, poly I:C and LPS) was investigated against acute X-ray irradiation and prolonged 60Co-gamma rays irradiation. The endogenous spleen colony formation test and percentage of surviving mice 30 days after irradiation were used as indicators. All interferon inducers investigated proved to have radioprotective activity.

Acridines↗
PubMed1978

Neoplastic response of turkey liver to MC29 leukosis virus.

Twelve to fourteen days after intravenous inoculation of MC29 virus (1 x 10(5)LD50) into 1-day-old turkeys, liver tumour developed in 100% of the infected animals and led to death of birds. The tumour proved to be hepatomas histologically and electron microscopically. Numerous C-type particles were detectable among the tumour cells, as well as budding from the cell membrane. C-type particles were also observed in the tumour-free liver tissue in the spaces between the cells, budding was not detectable. Large number of virus particles were found in spleen extracellularly and intracellular vacuoles. Kidney tumours did not develop, but a few extracellular virus particles were located in the tissue. The MC29 virus-induced primary liver tumour in the turkey seems to be a suitable model for the morphological study of the relationship between oncogenic viruses and eukaryotic cells.

Animals↗
PubMed1976

Interferon synthesis in mouse peritoneal cells damaged by X-irradiation.

NDV-induced interferon of peritoneal cells of irradiated (X-rays, 400 R) and control mice was investigated in vitro. Irradiation or treatment with hydroxyurea (10(-5) M) and mitomycin C (25 microng/ml) did not change interferon synthesis in spite of an 80--90% inhibition of 3H-thymidine incorporation. Increased doses of mitomycin C and treatment with actinomycin D and puromycin blocked interferon production. De novo interferon synthesis occurred in cells with damaged replicative activity of DNA caused by irradiation or by treatment with antimetabolites.

Amino Acids↗
PubMed1976

Effect of the interferon inducer tilorone in inbred CBA mice.

Tilorone hydrochloride (200 mg/kg) was administered intragastrically to inbred CBA mice. After 5, 18 and 48 hr the number of circulating leucocytes and peritoneal cells as well as the migration of unstimulated peritoneal cells, the blood corticosteroid level and interferon production were investigated. In spite of the considerable decrease of the number of mononuclear cells in the blood and polynuclear ones in the peritoneal exudate, the drug induced production of circulating interferon and stimulated its synthesis by peritoneal cells. The blood corticosteroid level and the mast cell count in the peritoneal cavity were significantly elevated, but the migration of peritoneal cells in antigen-free medium decreased.

Administration, Oral↗
PubMed1975

Comparison of the ability of small molecular interferon inducers: tilorone and acridine drugs.

The antiviral activity and induction of interferon-like substance by mepacrine (quinacrine, Atabrine) and Acranil in mice, described previuosly, was studied in more detail and compared with tilorone. The serum substance induced by Acranil was characterized as mouse interferon. Acranil, given parenterally, proved to be as strong as tilorone regarding interferon stimulation, in spite of the presence of only one side chain in the Acrainl molecule. Mepacrine was found to be a wealer interferon inducer than either tilorone or Acranil. The mode of interferon induction by Acranil and tilorone (effect of metabolic inhibitors, hyporesponsiveness to repeated doses, correlation between acute toxicity and antiviral activity, failure of effectiveness in chicks and chicken embryo tissue culture) was found comparable. However, the body temperature reactions of mice to the drugs were different: a striking hypothermic effect of tilorone, a lower one of mepacrine and the absence of body temperature depression by Acranil was observed.

Acridines↗