RESUMO
We have hypothesized that the adaptive response to low doses of ionizing radiation (IR) is mediated by oxidized cell-free DNA (cfDNA) fragments. Here, we summarize our experimental evidence for this model. Studies involving measurements of ROS, expression of the NOX (superoxide radical production), induction of apoptosis and DNA double-strand breaks, antiapoptotic gene expression and cell cycle inhibition confirm this hypothesis. We have demonstrated that treatment of mesenchymal stem cells (MSCs) with low doses of IR (10 cGy) leads to cell death of part of cell population and release of oxidized cfDNA. cfDNA has the ability to penetrate into the cytoplasm of other cells. Oxidized cfDNA, like low doses of IR, induces oxidative stress, ROS production, ROS-induced oxidative modifications of nuclear DNA, DNA breaks, arrest of the cell cycle, activation of DNA reparation and antioxidant response, and inhibition of apoptosis. The MSCs pretreated with low dose of irradiation or oxidized cfDNA were equally effective in induction of adaptive response to challenge further dose of radiation. Our studies suggest that oxidized cfDNA is a signaling molecule in the stress signaling that mediates radiation-induced bystander effects and that it is an important component of the development of radioadaptive responses to low doses of IR.
Assuntos
Efeito Espectador/efeitos da radiação , Ácidos Nucleicos Livres/metabolismo , Espaço Extracelular/metabolismo , Células-Tronco Mesenquimais/metabolismo , Células-Tronco Mesenquimais/efeitos da radiação , Radiação Ionizante , 8-Hidroxi-2'-Desoxiguanosina , Apoptose/efeitos da radiação , Ciclo Celular/efeitos da radiação , Linhagem Celular , Núcleo Celular/metabolismo , Núcleo Celular/efeitos da radiação , Proliferação de Células/efeitos da radiação , Sobrevivência Celular/efeitos da radiação , Dano ao DNA , Desoxiguanosina/análogos & derivados , Relação Dose-Resposta à Radiação , Proteínas de Fluorescência Verde/metabolismo , Histonas/metabolismo , Humanos , Oxirredução , Estresse Oxidativo/efeitos da radiação , Plasmídeos/metabolismoAssuntos
Células da Medula Óssea/efeitos dos fármacos , Mutagênicos/toxicidade , Troca de Cromátide Irmã/efeitos dos fármacos , Tiotepa/toxicidade , Animais , Células da Medula Óssea/ultraestrutura , Ciclo Celular , Cricetinae , Humanos , Técnicas In Vitro , Linfócitos/citologia , Linfócitos/efeitos dos fármacos , Linfócitos/ultraestrutura , Mitose , Phodopus , Fatores de TempoAssuntos
Cromossomos Humanos , Reparo do DNA , Adulto , Células Cultivadas , Feminino , Marcadores Genéticos , HumanosRESUMO
A thiophosphamide-induced increase of repair DNA-synthesis in lymphocytes in shown. To include cytogenetic studies in a genetic- and epidemiologic programme of genetic monitoring to make a complex assessment of health status of chemical industry workers is recommended.
Assuntos
Poluentes Ocupacionais do Ar/efeitos adversos , Indústria Química , Aberrações Cromossômicas/genética , Reparo do DNA/efeitos dos fármacos , Hidrocarbonetos/efeitos adversos , Linfócitos/efeitos dos fármacos , Troca de Cromátide Irmã/efeitos dos fármacos , Adulto , Células Cultivadas , Meios de Cultura , Reparo do DNA/genética , Humanos , Técnicas In Vitro , Linfócitos/ultraestrutura , Masculino , Pessoa de Meia-Idade , Troca de Cromátide Irmã/genética , Tiotepa/farmacologia , U.R.S.S.Assuntos
Agricultura , Poluentes Ocupacionais do Ar/efeitos adversos , Aberrações Cromossômicas/genética , Inseticidas/efeitos adversos , Linfócitos/efeitos dos fármacos , Mutação/efeitos dos fármacos , Desenvolvimento Vegetal , Troca de Cromátide Irmã/efeitos dos fármacos , Adulto , Feminino , Humanos , Técnicas In Vitro , Linfócitos/ultraestrutura , Pessoa de Meia-Idade , Mutagênicos , Mutação/genética , Troca de Cromátide Irmã/genética , U.R.S.S.RESUMO
The dynamics of sister chromatid exchanges and chromosome aberrations in lymphocyte of monkey has been investigated after a thiophosphamide exposure. The process of induction and elimination of cytogenetic damages was described by the mathematical model. Developing the model in detail will allow to make a cytogenetic prognosis of remote consequences of mutagenic exposure.
Assuntos
Aberrações Cromossômicas , Linfócitos/efeitos dos fármacos , Tiotepa/toxicidade , Animais , Células Cultivadas , Linfócitos/ultraestrutura , Macaca mulatta , Masculino , Matemática , Modelos Genéticos , Troca de Cromátide Irmã/efeitos dos fármacos , Fatores de TempoRESUMO
Thiophosphamide (T) was i.v. administered into New Zealand rabbit (4 mg/kg). The rate of SCE in blood lymphocytes was increased up to 21st day after T administration. There are two phases in dynamics curve of SCE--a rapid phase and a slow one. The rapid decrease of SCE's rate depends on cell mortality. The slow decrease of SCE rate is connected with reparation of chromosome damages and selection of cells in lymphopoietic tissue. It was demonstrated that the special class of cells with intermediate number of SCE exists in blood after T administration.
Assuntos
Troca de Cromátide Irmã/efeitos dos fármacos , Tiotepa/farmacologia , Animais , Sobrevivência Celular , Células Cultivadas , Linfócitos/efeitos dos fármacos , Linfócitos/ultraestrutura , Coelhos , Tiotepa/administração & dosagem , Fatores de TempoRESUMO
2.4 and 6 mg/kg thiophosphamide (T) was administered intravenously to New Zealand rabbits. A decrease in sister chromatid exchange (SCE) and chromosome aberration (CA) rate began immediately after the mutagenic action of T was over. The expected SCE rate was more than the investigated one. The difference between expected and investigated SCE rate increased with the dose of T. A calculation of SCE was based on the amount of the administered T, the rate of T removal and cell sensitivity to T. The death of cells with high number of SCE resulted in a fast decrease in SCE rate in the first 4 days. Reparative processes and cell proliferation in lymphocyte tissue resulted in a slow decrease in SCE rate after the 4th day. A number of nuclear cells in the blood was the smallest on the 4 th day, at the same time relative increase in CA rate was observed. The time of sampling and the dose of the substance tested should be taken into account for a more accurate estimation of mutagenic activity of some chemicals in in vivo cytogenetic tests.
Assuntos
Aberrações Cromossômicas , Troca de Cromátide Irmã , Animais , Relação Dose-Resposta a Droga , Metáfase/efeitos dos fármacos , Testes de Mutagenicidade/métodos , Coelhos , Troca de Cromátide Irmã/efeitos dos fármacos , Tiotepa/toxicidade , Fatores de TempoRESUMO
Mutagenic in vivo and in vitro effects were compared quantitatively by the investigation of sister chromatid exchange (SCE) rate and chromosomal aberrations caused by thiophosphamide in macaca rhesus lymphocytes. The integral of thiophosphamide concentration in the blood or culture fluid by a certain time period was used for the estimation of the dose of mutagenic exposure. It was shown that the dose-response relationships and corresponding regression coefficients were similar when the in vivo and in vitro results were compared. The data obtained indicate the possibility for quantitative extrapolation of the results obtained in vitro on the entire organism.
Assuntos
Aberrações Cromossômicas , Linfócitos/efeitos dos fármacos , Tiotepa/farmacologia , Animais , Relação Dose-Resposta a Droga , Técnicas In Vitro , Linfócitos/ultraestrutura , Macaca mulatta , Masculino , Mutação , Troca de Cromátide Irmã/efeitos dos fármacos , Fatores de TempoRESUMO
The comparative in vivo and in vitro study of chromosomal aberrations and SCE induced by cyclophosphamide (CP) in macaca rhesus lymphocytes was performed. The dose of mutagenic exposure for quantitative estimation of effects was determined as a product of concentration of alkylating CP metabolites on the exposure time. The mutagenic effect caused by the same doses of CP (CP metabolites) appeared similar in vivo and in vitro. This suggests that the results obtained in adequate in vitro mutagen-testing experiments may be quantitatively extrapolated for the in vivo conditions.
Assuntos
Aberrações Cromossômicas/efeitos dos fármacos , Ciclofosfamida/toxicidade , Linfócitos/efeitos dos fármacos , Mutagênicos , Animais , Técnicas In Vitro , Linfócitos/ultraestrutura , Macaca mulatta , Masculino , Troca de Cromátide Irmã/efeitos dos fármacosRESUMO
Cyclophosphamide (CP) and its metabolites were used to compare the rate of chromosomal aberrations (CA) and sister chromatid exchange (SCE) in the rabbit lymphocytes in vivo and in vitro. The dose-dependent increase of cytogenetic effects rate appeared to be of linear and exponential dependence for SCE and CA, respectively, both in vivo and in vitro. The regression equation coefficients coincided in in vivo and in vitro experiments.
Assuntos
Aberrações Cromossômicas , Ciclofosfamida/farmacologia , Mutagênicos , Troca de Cromátide Irmã/efeitos dos fármacos , Animais , Relação Dose-Resposta a Droga , Linfócitos/efeitos dos fármacos , Metáfase/efeitos dos fármacos , CoelhosRESUMO
A comparative study of cytogenetic effects in human lymphocytes caused in vivo by cyclophosphamide (CP) after intravenous injection and in vitro by exposure of plasma of the same patients was carried out. It was found that the frequency of induced chromosome aberrations (CA) and sister-chromatid exchanges (SCE) increased linearly for SCE and exponentially for CA within the 'dose' of alkylating activity of CP metabolites. Parameters of 'cytogenetic effect-dose' in vivo and in vitro coincided. The intensity of cytogenetic effects varied between individuals.
Assuntos
Ciclofosfamida/farmacologia , Linfócitos/efeitos dos fármacos , Mutação/efeitos dos fármacos , Troca de Cromátide Irmã/efeitos dos fármacos , Aberrações Cromossômicas , Relação Dose-Resposta a Droga , Humanos , Técnicas In Vitro , MetáfaseRESUMO
The dose dependences of chromosome aberrations rate were investigated in lymphocytes of oncological patients after cyclophosphamide (CP) administration. It was shown that the rate of chromosome aberrations and the number of disruptions per cell in vivo and in vitro increases exponentially with the dose. At the same time, the parameters of regression equations coincide. This evidences that CP has the similar effect in vivo and in vitro.
Assuntos
Aberrações Cromossômicas , Ciclofosfamida/farmacologia , Linfócitos/efeitos dos fármacos , Adulto , Células Cultivadas , Relação Dose-Resposta a Droga , Feminino , Humanos , Técnicas In Vitro , Linfócitos/ultraestrutura , Masculino , Pessoa de Meia-Idade , Mutação , Fatores de TempoRESUMO
A significant decrease in the baseline of sister-chromatid exchanges (SCEs) was observed in cultured human lymphocytes, if 5-bromodeoxyuridine (BrdU) was added after 60 h of culture, and the cells were harvested at least 24-30 h after BrdU exposure. This decrease is supposed to occur if at least one cell division takes place before the addition of BrdU. For cytogenetic monitoring of mutagenic environmental factors, using human lymphocyte cultures, it is assumed that two time periods are sufficient for comparison.
Assuntos
Sobrevivência Celular , Troca Genética , Linfócitos/citologia , Troca de Cromátide Irmã , Bromodesoxiuridina , Células Cultivadas , Feminino , Humanos , MasculinoRESUMO
Thiophosphamide is capable of inhibiting the cell cycle after the treatment of rabbit blood lymphocytes in vivo and in vitro. To assess the proliferative activity of the cells during cultivation, use was made of the index of the mean division number which was experienced by the cells after mutagenic exposure prior to fixation. As the mutagen dose was raised in vivo and in vitro, the mean division number decreased linearly, namely by approximately the same value with an equivalent dose variation. This indicates that thiophosphamide produces the same cytotoxic action both in vivo and in vitro.
Assuntos
Linfócitos/efeitos dos fármacos , Mutagênicos , Tiotepa/farmacologia , Animais , Divisão Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Técnicas In Vitro , CoelhosRESUMO
Cytogenetic effects after i. v. administration of thiophosphamide were investigated in rabbit lymphocytes. It was observed, that the rate of chromosome aberrations and SCE increased within a matter of first 6 hours.
Assuntos
Aberrações Cromossômicas/efeitos dos fármacos , Troca Genética/efeitos dos fármacos , Mutagênicos , Troca de Cromátide Irmã/efeitos dos fármacos , Tiotepa/toxicidade , Animais , Relação Dose-Resposta a Droga , Linfócitos/ultraestrutura , Coelhos , Fatores de TempoRESUMO
The effects of thiophosphamide on rabbit lymphocytes were studied and compared in vivo and in vitro. In the course of in vitro action the dose was calculated by multiplying the thiophosphamide concentration by the time of in vitro treatment. In vivo the dose was calculated as integral of concentration variation function of thiophosphamide from the time of injection till the time of blood collection. It was demonstrated that as the dose was raised, the rate of sister chromatid exchanges increased linearly in vivo and in vitro. The coefficients of linear regressions were found to coincide. The data point to equal efficacy of thiophosphamide in vivo and in vitro.
Assuntos
Troca Genética/efeitos dos fármacos , Troca de Cromátide Irmã/efeitos dos fármacos , Tiotepa/farmacologia , Animais , Células Cultivadas , Relação Dose-Resposta a Droga , Técnicas In Vitro , Linfócitos/efeitos dos fármacos , Linfócitos/ultraestrutura , Mutação , Coelhos , Análise de RegressãoRESUMO
Rabbit lymphocytes were treated with thiophosphamide in vivo and in vitro. In-vitro doses were calculated by multiplying thiophosphamide concentrations by the time of treatment (the doses ranged within 0-1500 mg/min/ml). In-vivo doses were calculated as integral of thiophosphamide concentration function from the time of administration till the time of blood sample collection (the doses ranged within 0-1900 mg/min/ml). It was shown that with the dose increase the rate of chromosome aberrations and the number of disruptions per cell rise exponentially in vivo and in vitro. At the same time the parameters of regression equations coincide. This evidences that thiophosphamide produces the same effect in vivo and in vitro.
Assuntos
Aberrações Cromossômicas , Linfócitos/efeitos dos fármacos , Tiotepa/farmacologia , Animais , Relação Dose-Resposta a Droga , Técnicas In Vitro , Mitose/efeitos dos fármacos , Mutagênicos/farmacologia , CoelhosRESUMO
CBA mice were immunized with sheep red blood cells (SRBC) to obtain immune spleen cells (ISc) which were used to suppressor cells. Administration of ISC to intact syngeneic recipients on the immunization day led to a more powerful suppression of the immune response as compared to that seen one day after antigen injection. Four days after immunization the animals' immune response was not liable to be suppressed. ISC extract possessed similar effects with respect to the immune response of normal spleen cells which were transplanted to the cyclophosphamide-treated recipients. The immune response of spleen cells from mice immunized with SRBC in a dose of 10(6) was less liable to be suppressed. Hyperimmune spleen cells from donors immunized with SRC in a dose of 10(9) were insensitive to ISC or to the extract. Experiments with the use of adoptive transfer of a mixture of immune and intact T- and B-cells have disclosed that B-cells from hyperimmune donors were resistant to suppression. Therefore, B-lymphocytes are the most probable target cells exposed to T-suppressors in the given system. The mechanism is discussed of the selective effect of T-suppressors on B-cells in the course of the immune response development during immunization with high doses of antigen.