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1.
Mutat Res ; 628(2): 129-37, 2007 Apr 02.
Artículo en Inglés | MEDLINE | ID: mdl-17267263

RESUMEN

Peptide nucleic acids (PNAs) are synthetic homolog of nucleic acids in which the phosphate-sugar polynucleotide backbone is replaced by a flexible polyamide. They bind complementary polynucleotide sequences with higher affinity and specificity than their natural counterparts. PNAs linked to the appropriate nuclear localization signal (NLS) peptide have been used to selectively down-regulate the expression of several genes in viable cells. For example in Burkitt's lymphoma (BL) cells the c-myc oncogene is translocated in proximity to the Emu enhancer of the Ig gene locus and upregulated. PNAs complementary to the second exon of c-myc or to the Emu enhancer sequence (PNAEmu-NLS), selectively and specifically block the expression of the c-myc oncogene and inhibit cell growth in vitro and in vivo. PNAEmu-NLS administration to mice did not exhibit toxic effects even at the highest concentration allowed by the experimental conditions. Because of the accumulating data confirming PNAEmu-NLS potential therapeutic value, PNAEmu-NLS was evaluated for the inability to induce mutations in tester strains of Salmonella typhimurium, Escherichia coli, and at the hprt locus in Chinese hamster ovary cells (CHO). Moreover, the induction of chromosomal aberrations in CHO cells and of micronuclei in human lymphocytes were investigated. We may conclude that PNAEmu-NLS neither induces mutations nor has clastogenic effects as detectable by treatment under the standard test conditions.


Asunto(s)
Linfoma de Burkitt/genética , Elementos de Facilitación Genéticos , Cadenas mu de Inmunoglobulina/toxicidad , Mutágenos/toxicidad , Señales de Localización Nuclear/toxicidad , Ácidos Nucleicos de Péptidos/toxicidad , Proteínas Proto-Oncogénicas c-myc/antagonistas & inhibidores , Animales , Células CHO , Cricetinae , Cricetulus , Escherichia coli , Humanos , Hipoxantina Fosforribosiltransferasa/genética , Linfocitos/efectos de los fármacos , Pruebas de Micronúcleos , Transporte de Proteínas , Proteínas Proto-Oncogénicas c-myc/genética , Proteínas Proto-Oncogénicas c-myc/metabolismo , Salmonella typhimurium
2.
Cytotechnology ; 5(Suppl 1): 51-4, 1991 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-22358953

RESUMEN

Toxicity testing is required for new chemicals being introduced onto the market. The use of animals in evaluating chemical safety is costly and time consuming. Furthermore, there is the ethical need to develope alternative methods to reduce the required number of animals. The newin vitro assays offer numerous advantages such as speed, reproducibility and control of test conditions, and increased sensitivity. Although the dermal irritation assays might be substituted by thein vitro tests in the near future (Duffy, 1989), much work is required to evaluate organ toxicity within vitro methods. We present data regarding the use of Balb/3T3 mice fibroblasts and primary rat hepatocytes as test systems forin vitro toxicity. The end-points we have analysed are total protein content, dye accumulation in lysosomes, reductase mytochondrial activity, intracellular content and leakage of enzymes into the medium.

3.
Mutagenesis ; 6(4): 319-24, 1991 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-1719337

RESUMEN

In the framework of the coordinated programme 'Genomic Mutations' sponsored by the Commission of European Communities, eight known or suspected spindle poisons (cadmium chloride, chloral hydrate, colchicine, diazepam, econazole, hydroquinone, pyrimethamine, thiabendazole, thimerosal and vinblastine) were tested in a modified in vitro micronucleus test in Chinese hamster cells. Micronuclei (MN) with or without kinetochore were analyzed by staining of the kinetochore with an antikinetochore antibody (CREST staining). Mitotic index and ana-telophase:mitosis ratio were also recorded to evaluate cytotoxicity and c-mitotic effects of tested chemicals. CREST-positive MN were induced by diazepam, thiabendazole and vinblastine. Hydroquinone, pyrimethamine, econazole and cadmium chloride induced MN that contained both entire chromosomes and acentric fragments. Negative results were obtained with thimerosal. The results obtained indicate that the detection of CREST-positive MN is a powerful assay to identify spindle poisons. Furthermore, this method provides a useful tool to ascertain the origin(s) of induced MN.


Asunto(s)
Aberraciones Cromosómicas , Cromosomas/ultraestructura , Pruebas de Micronúcleos , Huso Acromático/efectos de los fármacos , Aneuploidia , Anticuerpos Monoclonales , Cadmio/toxicidad , Cloruro de Cadmio , Línea Celular , Hidrato de Cloral/toxicidad , Cromosomas/inmunología , Colchicina/toxicidad , Diazepam/toxicidad , Econazol/toxicidad , Micronúcleos con Defecto Cromosómico/química , Índice Mitótico/efectos de los fármacos , Coloración y Etiquetado , Vinblastina/toxicidad
4.
Cytotechnology ; 5 Suppl 1: 51-4, 1991.
Artículo en Inglés | MEDLINE | ID: mdl-1367120

RESUMEN

Toxicity testing is required for new chemicals being introduced onto the market. The use of animals in evaluating chemical safety is costly and time consuming. Furthermore, there is the ethical need to develop alternative methods to reduce the required number of animals. The new in vitro assays offer numerous advantages such as speed, reproducibility and control of test conditions, and increased sensitivity. Although the dermal irritation assays might be substituted by the in vitro tests in the near future (Duffy, 1989), much work is required to evaluate organ toxicity with in vitro methods. We present data regarding the use of Balb/3T3 mice fibroblasts and primary rat hepatocytes as test systems for in vitro toxicity. The end-points we have analysed are total protein content, dye accumulation in lysosomes, reductase mitochondrial activity, intracellular content and leakage of enzymes into the medium.


Asunto(s)
Alternativas a las Pruebas en Animales/métodos , Toxicología/métodos , Animales , Células Cultivadas , Fibroblastos/efectos de los fármacos , Hígado/efectos de los fármacos , Masculino , Ratones , Ratones Endogámicos BALB C , Ratas
5.
Carcinogenesis ; 17(11): 2529-33, 1996 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-8968074

RESUMEN

7,12-Dimethylbenz[a]anthracene (DMBA), which is widely used in mutagenesis and experimental carcinogenesis, is activated to a mutagen by white fluorescent light. A 40 min exposure to white fluorescent light of Salmonella typhimurium TA98 plates treated with DMBA, in the absence of exogenous metabolism, resulted in an approximately 30-fold increase in the number of histidine revertants. This phenomenon also occurs, with lesser intensity, with other promutagens, such as benzo[a]pyrene or 2-acetylaminofluorene, and in other Salmonella tester strains. Moreover, white fluorescent light is able to activate DMBA to a toxicant for Chinese hamster V79 cells in culture, resulting in very low cell survival. Under these conditions, white fluorescent light-activated DMBA was shown to cause chromosomal aberrations, but not gene mutations, as determined by resistance to thioguanine. This white fluorescent light-dependent activation of DMBA seems to be related to the formation of reactive species, as the addition of vitamin E results in a reduction in the number of histidine revertants induced by white fluorescent light in S. typhimurium TA98.


Asunto(s)
9,10-Dimetil-1,2-benzantraceno/farmacocinética , 9,10-Dimetil-1,2-benzantraceno/efectos de la radiación , 9,10-Dimetil-1,2-benzantraceno/toxicidad , Animales , Biotransformación/efectos de la radiación , Cricetinae , Cricetulus , Histidina/metabolismo , Luz , Pruebas de Mutagenicidad , Salmonella typhimurium/efectos de los fármacos , Salmonella typhimurium/efectos de la radiación
6.
Arzneimittelforschung ; 47(4A): 511-4, 1997 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-9205754

RESUMEN

Five genotoxicity studies on ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)amino]-4-thiazolyl]methyl]thio] ethyl]amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542), including at least four of the battery of tests recommended by toxicological regulatory guidelines for new drugs, were conducted. These tests were the Ames test for determination of bacterial gene mutations, sex-linked recessive lethal mutation test in Drosophila for gene mutations in eukaryotic systems, in vitro chromosome aberration test and micronucleus test for evaluation of structural and numerical aberrations, and sister chromatid exchange frequency test for assessment of non-specific damage to chromatin. Negative and positive controls were used in all the experiments. The effects were investigated in the absence or presence of metabolic activation by S-9 microsomal fraction from rat liver homogenate. A dose range toxicity study was also performed to determine the dosage levels or concentrations to be tested for the assessment of genotoxic effects. None of the tests showed a significant increase in the genotoxic parameters, both in vitro and in vivo in somatic or germ cells. It is, therefore, concluded that ebrotidine has not caused mutagenic or clastogenic effects in any of the experimental systems tested.


Asunto(s)
Bencenosulfonatos/toxicidad , Genes/efectos de los fármacos , Antagonistas de los Receptores H2 de la Histamina/toxicidad , Tiazoles/toxicidad , Animales , Aberraciones Cromosómicas , Drosophila melanogaster/genética , Eritrocitos/efectos de los fármacos , Genes Bacterianos/efectos de los fármacos , Humanos , Linfocitos/efectos de los fármacos , Ratones , Pruebas de Micronúcleos , Pruebas de Mutagenicidad , Salmonella typhimurium/genética , Intercambio de Cromátides Hermanas
7.
Mutagenesis ; 14(2): 207-15, 1999 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-10229923

RESUMEN

Ten halogenated aliphatic hydrocarbons (carbon tetrachloride, 1-chlorohexane, 2,3-dichlorobutane, 1,2-dichloroethane, 1,2-dichloroethylene, 1,3-dichloropropane, hexachloroethane, 1,1,2-trichloroethane, 1,2,3-trichloropropane and 1,1,3-trichloropropene), previously assayed in genetic assays in fungi, were evaluated in the mouse bone marrow micronucleus test in order to assess their genotoxicity in vivo. All chemicals were administered once i.p. at 40 and 70-80% of their respective LD50 to male and female CD-1 mice, 24 and 48 h before killing. All treatments produced evident clinical symptoms, but no marked depression of bone marrow proliferation. No statistically significant increases in the incidence of micronucleated polychromatic erythrocytes over the control values were observed at any sampling time with any of the 10 halogenated hydrocarbons assayed. The comparison of the results obtained in this study with the findings provided by in vitro micronucleus assays on the same chemicals, reported by other authors, indicate that mouse bone marrow is weakly sensitive to the genotoxic effects induced by halogenated hydrocarbons in other test systems. This suggests that the role of such an assay in carcinogen screening may be questionable for this chemical class. An examination of mouse bone marrow micronucleus test results with the halogenated aliphatic hydrocarbons classified as carcinogens by IARC supports this conclusion.


Asunto(s)
Médula Ósea/efectos de los fármacos , Hidrocarburos Halogenados/toxicidad , Pruebas de Micronúcleos , Mutágenos/farmacología , Animales , Femenino , Hidrocarburos Halogenados/administración & dosificación , Cinética , Dosificación Letal Mediana , Masculino , Ratones , Ratones Endogámicos ICR , Sensibilidad y Especificidad
8.
Mutagenesis ; 12(3): 163-7, 1997 May.
Artículo en Inglés | MEDLINE | ID: mdl-9175642

RESUMEN

Human lymphocyte cultures have been used for many years for assessing the in vitro clastogenic potential of test substances. In these assays the harvest time should be based on the cell cycle time in order to ensure that cells are sampled at an appropriate time for the detection of clastogenic effects. The sources of variation in the cell cycle time in routine cytogenetic assays have not been well studied. Consequently 13 laboratories, all members of the Industrial Genotoxicology Group, participated in a collaborative study to measure the variation in cell cycle time in cultured human peripheral blood lymphocytes under various conditions. The study was performed in two phases, spaced 6 months apart. The average generation time (AGT) was measured by the incorporation of bromodeoxyuridine. Very similar AGTs were found in the presence and absence of S9 mix. The mean AGT (mean of four donors) in each laboratory varied from 11.2 to 17.1 h, indicating there is significant variability in cell cycle times of human peripheral blood lymphocytes between laboratories. There was greater variation between laboratories than within laboratories. A comparison of AGT values at 72 h performed in experiments at least 6 months apart indicated good reproducibility in most laboratories. The study indicates that a 24 h post-treatment harvest may result in the analysis of very few first division cells unless very significant cell cycle delay is induced by the test substance. It was also found that a post-harvest time equivalent to 1.5 cell cycles will result in an approximately equal mixture of first and second division cells and therefore should by suitable for assessing both the induction of chromosome aberrations and polyploidy.


Asunto(s)
Ciclo Celular , Citogenética/métodos , Linfocitos/citología , Linfocitos/efectos de los fármacos , Mutágenos/toxicidad , Animales , Bromodesoxiuridina/metabolismo , Células Cultivadas , Aberraciones Cromosómicas , Estudios de Evaluación como Asunto , Humanos , Técnicas In Vitro , Laboratorios , Linfocitos/metabolismo , Microsomas Hepáticos/metabolismo , Pruebas de Mutagenicidad/métodos , Mutágenos/metabolismo , Poliploidía , Ratas , Factores de Tiempo
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