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1.
Article in English | MEDLINE | ID: mdl-32087845

ABSTRACT

A database of micronuclei counts for historical negative control data from rat in vivo micronuclei tests performed in 10 different laboratories was established. Data were available from over 4000 negative control rats from 10 laboratories. The mean frequency of micronucleated cells (MN)/1000 cells ranged from 0.44 to 2.22, a 5-fold range. Overall there were no major sex or strain differences in frequency, although there were some small but statistically significant differences within laboratories. There was appreciable variability between experiments compared with variability within experiments in some laboratories. No specific factor was identified which could explain this variability although it was noted that many different vehicles were used in the experiments. It is hoped that these data will help laboratories beginning studies with the rat micronucleus assay and those involved in the assessment of micronucleus assay results.


Subject(s)
Laboratory Proficiency Testing/statistics & numerical data , Micronuclei, Chromosome-Defective/statistics & numerical data , Micronucleus Tests/standards , Animals , Female , Male , Micronucleus Tests/statistics & numerical data , Observer Variation , Quality Control , Rats , Rats, Sprague-Dawley , Rats, Wistar , Reproducibility of Results
2.
SAR QSAR Environ Res ; 31(1): 33-48, 2020 Jan.
Article in English | MEDLINE | ID: mdl-31766891

ABSTRACT

Over the past years, the European Food Safety Authority (EFSA) released to the public domain several databases, with the main objectives of collecting and storing hazard data on the substances considered in EFSA's risk assessment and secondly to serve as a basis for further development of in silico tools such as quantitative structure-activity relationship (QSAR) models. In this work, we evaluated the ability of freely available QSAR models to estimate genotoxicity and carcinogenicity properties and their possible use for screening purposes on three different EFSA's databases. With an accuracy close to 90%, the results showed good capabilities of QSAR models to predict genotoxicity in terms of bacterial reverse mutation test, while statistics for in vivo micronucleus test are not satisfactory (accuracy in the predictions close to 50%). Interestingly, results on the carcinogenicity assessment showed an accuracy in prediction close to 70% for the best models. In addition, an example of the potential application of in silico models is presented in order to provide a preliminary screening of genotoxicity properties of botanicals intended for use as food supplements.


Subject(s)
Carcinogenicity Tests/statistics & numerical data , Mutagenicity Tests/statistics & numerical data , Quantitative Structure-Activity Relationship , Bacteria/drug effects , Bacteria/genetics , Databases, Factual , Micronucleus Tests/statistics & numerical data , Models, Theoretical , Mutation/genetics , Reproducibility of Results , Risk Assessment
3.
Sci Rep ; 9(1): 14898, 2019 10 17.
Article in English | MEDLINE | ID: mdl-31624274

ABSTRACT

Smoking and smokeless tobacco consumption is a significant risk factor that provokes genetic alterations. The present investigation was to evaluate the biomarkers of genotoxicity including micronucleus (MN), chromosome aberrations (CA) and DNA strand breaks among tobacco consumers and control individuals residing in hilly areas of Western Ghats, Tamilnadu, South India. This study included 268 tobacco consumers with equal number of controls. The tobacco consumers were divided into Group I (<10 years of tobacco consumption with an age range from 15 to 35 years) and group II (>10 years consumption above 35 years of age). Chromosome aberration (CA) and comet assay were performed using blood and micronucleus assay from exfoliated buccal epithelial cells obtained from tobacco consumers and controls. Elevated levels of CA were found in group II (Chromatid type: 2.39 ± 1.13 and chromosome type: 1.44 ± 1.24) exposed subjects, high micronucleus and DNA damage (TL:4.48 ± 1.24 and TM:3.40 ± 1.58) levels were significantly (p < 0.05) observed in both smoking and smokeless tobacco consumers when comparison with group I and controls. This study also observed a lack of awareness among the tobacco consumers about the harmful health effects of tobacco. Tobacco consumption contributes to the significant alteration in genetic materials. In addition, a high rate of spontaneous abortion was also seen in the studied population.


Subject(s)
Abortion, Spontaneous/epidemiology , DNA Damage/drug effects , Micronuclei, Chromosome-Defective/chemically induced , Tobacco Use/adverse effects , Tobacco, Smokeless/toxicity , Abortion, Spontaneous/chemically induced , Adult , Aged , Case-Control Studies , Comet Assay/statistics & numerical data , Epithelial Cells/pathology , Female , Humans , India/epidemiology , Male , Micronuclei, Chromosome-Defective/statistics & numerical data , Micronucleus Tests/statistics & numerical data , Middle Aged , Mouth Mucosa/pathology , Time Factors , Tobacco Use/blood , Young Adult
4.
Regul Toxicol Pharmacol ; 102: 13-22, 2019 Mar.
Article in English | MEDLINE | ID: mdl-30572081

ABSTRACT

Recent updates of the OECD Guidelines for the Testing of Chemicals (Section 4: Health Effects) on genotoxicity testing emphasize the use of appropriate statistical methods for data analysis and proficiency proof. Updates also concern the mammalian erythrocyte micronucleus test (OECD 474), as the currently most often performed regulatory in vivo test. As the updated guideline gives high importance to adequate statistical assessment of historical negative control data to estimate validity of experiments and judge results, the present study evaluated statistical methodologies for handling of historical negative control data sets, and comes forward with respective proposals and reference data. Therefore, the working group "Statistics" within the German-speaking "Gesellschaft für Umwelt-Mutationsforschung e.V." (GUM) compiled a data set of 891 negative control rats from valid OECD 474-studies of four laboratories. Based on these data, Analysis-of-Variance (ANOVA) identified "laboratory" and "strain", but not "gender" as relevant stratification parameters, and argued for approximately normally distributed micronucleus frequencies in polychromatic erythrocytes per animal. This assumption provided the basis for further specifying one-sided parametric tolerance intervals for determination of corresponding upper historical negative control limits. Finally, the stability of such limits was investigated as a function of the number of experiments performed, using a simulation-based statistical strategy.


Subject(s)
Control Groups , Micronucleus Tests/statistics & numerical data , Animals , Bone Marrow , Female , Male , Rats, Wistar , Reference Values
5.
Gig Sanit ; 96(2): 121-4, 2017.
Article in Russian | MEDLINE | ID: mdl-29446592

ABSTRACT

The study have been conducted in settlements located near oilfields of the Nizhnevartovsk area, the Khanty-Mansi autonomous district (Russian Federation). There were examined 802 persons aged of from 18 to 56 years not proximately employed in processes of the oil extraction. Control group was consisted of329 residents of the north of Tomsk Region living in the area without any polluting environment industry. By using such methods of analysis as micronucleus test in human buccal cells, the xenobiotic biotransformation of both GSTM1 and GSTT1 gene polymorphism, as well as the assessment of oil contamination of local drinking water there was executed the hygienic assessment of ecology in the settlements located near oil fields. The elevated rate of cytogenetic disorders was established to be observed most of all in the residents of this region, as well as in persons recently moved to this area. Most significant deviations from the control according to the micronucleus test were detected in individuals with the GSTM1 (0) /GSTT1(0) genotype. In the control group no such consistent pattern was seen.


Subject(s)
Cytogenetic Analysis , Environmental Pollution , Micronucleus Tests , Oil and Gas Industry , Cytogenetic Analysis/methods , Cytogenetic Analysis/statistics & numerical data , Environmental Exposure/analysis , Environmental Exposure/prevention & control , Environmental Monitoring/methods , Environmental Pollution/adverse effects , Environmental Pollution/analysis , Environmental Pollution/prevention & control , Humans , Micronucleus Tests/methods , Micronucleus Tests/statistics & numerical data , Mouth Mucosa/pathology , Oil and Gas Industry/standards , Oil and Gas Industry/statistics & numerical data , Public Health/methods , Siberia/epidemiology , Time Factors
6.
Anon.
Acta toxicol. argent ; 24(3): 193-199, dic. 2016. ilus, tab
Article in Spanish | LILACS | ID: biblio-837866

ABSTRACT

O Rio dos Sinos está localizado na região sul do Brasil, possui aproximadamente 190 km de extensão e fornece água para atividades agrícolas, industriais e para o consumo de mais de um milhão de habitantes. Este rio é considerado um dos mais poluídos do Brasil e, portanto, estudos para avaliar a qualidade da água ao longo de sua extensão são necessários. O teste de micronúcleos em eritrócitos de peixes tem sido utilizado com sucesso para detectar a presença de poluentes mutagênicos nos ambientes aquáticos. O objetivo do presente estudo foi avaliar a qualidade da água do Rio dos Sinos por meio do teste de micronúcleos em Cyprinus carpio bem como de análises físico-químicas e microbiológicas. Foram coletadas amostras de água nos trechos superior (Caraá), médio (Parobé) e inferior (Novo Hamburgo) do Rio dos Sinos em dezembro de 2013. As amostras foram transportadas para o laboratório para análise de 14 parâmetros de qualidade da água bem como para a exposição de espécimes de C. carpio por 72h em aquários. Não foram verificadas diferenças significativas na frequência de micronúcleos e anormalidades nucleares nos grupos expostos a água do rio em comparação ao grupo controle. Apenas um parâmetro de qualidade da água foi observado em desacordo com a legislação no trecho superior do rio, enquanto que nos trechos médio e inferior foram seis e cinco parâmetros, respectivamente. Os resultados demonstram que o Rio dos Sinos apresenta redução da qualidade da água ao longo de sua extensão e indicam ausência de potencial genotóxico no período amostrado.


The Sinos River is located in South of Brazil, it has about 190 km of extension and provides water for agricultural and industrial activities, and for consumption of more than one million inhabitants. This river is considered one of the most polluted rivers in Brazil; therefore, studies aiming to evaluate the water quality along its course are necessary. The micronucleus test in fish erythrocytes has been successful used to detect mutagenic pollutants in the aquatic environment. The objective of this study was to evaluate the water quality of the Sinos River by the micronucleus test in Cyprinus carpio, as well as physicochemical and microbiological analyses. Water samples were collected in the upper (Caraá municipality), middle (Parobé municipality) and lower (Novo Hamburgo municipality) sections of the Sinos River, in December 2013. The samples were transported to the laboratory for analysis of 14 water quality parameters and for exposure of C. carpio for 72 hours in aquaria. Significant differences in micronucleus and nuclear abnormalities frequencies were not found between the control and the exposed groups. Only one parameter of water quality exceeded the limit of the legislation in the upper section of the river, while in the middle and lower sections, six and five parameters, respectively. These results show that the Sinos River presents a reduction in water quality along its extension and indicates the absence of genotoxic potential in the sampled period.


Subject(s)
Animals , Carps/abnormalities , Micronucleus Tests/statistics & numerical data , Rivers/microbiology , Water Quality , Brazil/epidemiology , Genotoxicity/analysis , Microbiological Techniques/methods , Chemical Phenomena/methods , River Pollution/analysis , Water Samples
7.
Environ Mol Mutagen ; 57(8): 623-629, 2016 10.
Article in English | MEDLINE | ID: mdl-27545269

ABSTRACT

Statistical methods currently recommended for analysis of in vitro micronucleus data are based on small sample sizes. The tests are designed to evaluate linear trends and differences between treated and control samples. When using flow cytometric analysis, >5 times the number of cells are easily evaluated, and the variance estimates from these large samples are small. Application of these recommended tests to large samples resulted in statistically significant outcomes which were not considered to be biologically meaningful. Alternative statistical methods for testing trends and differences among treatments that were either widely used, or sample-size independent, were investigated. Using data from 95 experiments (from 2011-2013) where 19% of the experiments were considered positive, results for the various statistical methods were compared. When using either the recommended or alternate methods, 42-68% of the experiments resulted in statistically significant results (p < 0.05). A new concept was then tested using the same data sets: the "z' factor", designed to identify 'hits' during high throughput screening. Using this simple-to-compute statistic the number of significant calls was reduced to 27%. Then, when combined with a biological criterion based on historical vehicle control data, there was restoration of the original positive frequency (19%). Given the larger sample sizes evaluated using flow cytometry, we have demonstrated that traditional statistical tests may be overly sensitive to small changes in micronucleus induction, and that a simple-to-compute index of separation (z') may be a better tool for analysis, provided that the response is first determined to be biologically meaningful. Environ. Mol. Mutagen. 57:589-604, 2016. © 2016 Wiley Periodicals, Inc.


Subject(s)
Data Interpretation, Statistical , Flow Cytometry/statistics & numerical data , Micronuclei, Chromosome-Defective/statistics & numerical data , Micronucleus Tests/statistics & numerical data , Animals , CHO Cells , Cell Culture Techniques , Cell Survival/drug effects , Cricetulus , Dose-Response Relationship, Drug , Micronuclei, Chromosome-Defective/chemically induced , Models, Statistical , Xenobiotics/toxicity
8.
Arch Toxicol ; 90(7): 1631-8, 2016 Jul.
Article in English | MEDLINE | ID: mdl-26438403

ABSTRACT

The vast majority of toxicological papers summarize experimental data as bar charts of means with error bars. While these graphics are easy to generate, they often obscure essential features of the data, such as outliers or subgroups of individuals reacting differently to a treatment. In particular, raw values are of prime importance in toxicology; therefore, we argue they should not be hidden in messy supplementary tables but rather unveiled in neat graphics in the results section. We propose jittered boxplots as a very compact yet comprehensive and intuitively accessible way of visualizing grouped and clustered data from toxicological studies together with individual raw values and indications of statistical significance. A web application to create these plots is available online.


Subject(s)
Computer Graphics , Computer Simulation , Models, Statistical , Toxicology/statistics & numerical data , Algorithms , Animals , Cluster Analysis , Data Interpretation, Statistical , Micronucleus Tests/methods , Micronucleus Tests/statistics & numerical data , Rats , Sample Size , Toxicity Tests/methods , Toxicity Tests/statistics & numerical data , Toxicology/methods , User-Computer Interface
9.
Gig Sanit ; 95(10): 969-73, 2016.
Article in Russian | MEDLINE | ID: mdl-29431345

ABSTRACT

There are presented results of the cytome analysis of epithelium of buccal mucosa in 167 children aged of 5-7 years, permanently residing in the city of Magnitogorsk and visiting municipal kindergartens. Frequencies of the main indices of genotoxic and toxic effects were: cells with micronuclei - 0.29±0.04 %, with protrusions ofnuclei - 1.47±0.17 %, with double nuclei -1.96±0.13 %, with two nuclei - 3,28±0,16 %, with perinuclear vacuole - 9.66±0.86 %, with pycnosis of nucleus - 4.60±0.31 per 1000 cells, with karyorrhexis - 0.86±0.15per 1000 cells, with lysis of nucleus - 54.34±3.90 per 1000 cells, the condensed chromatin cells - 10.59±1.35 per 1000 cells. Most of these indices didn't differ from the same detected earlier in buccal epithelial cells from children of the same age in Moscow, except cells with perinuclear vacuole, which frequency in Moscow cohort was twice higher. Frequencies of cells with these anomalies were associated with the content of 19 out of 326 revealed components of contamination of the total-winter snow samples, taken on the territories of the kindergartens, which were visited by examined children. There was shown lack of differences from basic values of main indices previously establishedfor the children of the same age in Moscow, with the exception of cells with perinuclear vacuole, the rate of which in Moscow was twice higher. There were revealed confounding factors associated with test indices: gender of the child, the annual number of acute respiratory diseases, health group, income per one person in family, alcohol intake by parents.


Subject(s)
Environmental Exposure , Micronucleus Tests , Mouth Mucosa/pathology , Water Pollution , Child , Child, Preschool , Environmental Exposure/adverse effects , Environmental Exposure/analysis , Female , Health Status Disparities , Humans , Male , Micronucleus Tests/methods , Micronucleus Tests/statistics & numerical data , Risk Assessment/methods , Risk Assessment/statistics & numerical data , Risk Factors , Russia/epidemiology , Snow , Water Pollution/adverse effects , Water Pollution/analysis
10.
Mutagenesis ; 29(3): 155-64, 2014 May.
Article in English | MEDLINE | ID: mdl-24705543

ABSTRACT

Micronucleus (MN) induction is an established cytogenetic end point for evaluating structural and numerical chromosomal alterations in genotoxicity testing. A semi-automated scoring protocol for the assessment of MN preparations from human cell lines and a 3D skin cell model has been developed and validated. Following exposure to a range of test agents, slides were stained with 4'-6-diamidino-2-phenylindole (DAPI) and scanned by use of the MicroNuc module of metafer 4, after the development of a modified classifier for selecting MN in binucleate cells. A common difficulty observed with automated systems is an artefactual output of high false positives, in the case of the metafer system this is mainly due to the loss of cytoplasmic boundaries during slide preparation. Slide quality is paramount to obtain accurate results. We show here that to avoid elevated artefactual-positive MN outputs, diffuse cell density and low-intensity nuclear staining are critical. Comparisons between visual (Giemsa stained) and automated (DAPI stained) MN frequencies and dose-response curves were highly correlated (R (2) = 0.70 for hydrogen peroxide, R (2) = 0.98 for menadione, R (2) = 0.99 for mitomycin C, R (2) = 0.89 for potassium bromate and R (2) = 0.68 for quantum dots), indicating the system is adequate to produce biologically relevant and reliable results. Metafer offers many advantages over conventional scoring including increased output and statistical power, and reduced scoring subjectivity, labour and costs. Further, the metafer system is easily adaptable for use with a range of different cells, both suspension and adherent human cell lines. Awareness of the points raised here reduces the automatic positive errors flagged and drastically reduces slide scoring time, making metafer an ideal candidate for genotoxic biomonitoring and population studies and regulatory genotoxic testing.


Subject(s)
Micronucleus Tests/methods , Cell Culture Techniques , Cell Line , Chromosome Breakage/drug effects , Fluorescent Dyes , Humans , Indoles , Keratinocytes/drug effects , Keratinocytes/pathology , Micronuclei, Chromosome-Defective/drug effects , Micronucleus Tests/statistics & numerical data , Mutagens/toxicity
11.
Mutagenesis ; 29(3): 165-75, 2014 May.
Article in English | MEDLINE | ID: mdl-24675152

ABSTRACT

Recent restrictions on the testing of cosmetic ingredients in animals have resulted in the need to test the genotoxic potential of chemicals exclusively in vitro prior to licensing. However, as current in vitro tests produce some misleading positive results, sole reliance on such tests could prevent some chemicals with safe or beneficial exposure levels from being marketed. The 3D human reconstructed skin micronucleus (RSMN) assay is a promising new in vitro approach designed to assess genotoxicity of dermally applied compounds. The assay utilises a highly differentiated in vitro model of the human epidermis. For the first time, we have applied automated micronucleus detection to this assay using MetaSystems Metafer Slide Scanning Platform (Metafer), demonstrating concordance with manual scoring. The RSMN assay's fixation protocol was found to be compatible with the Metafer, providing a considerably shorter alternative to the recommended Metafer protocol. Lowest observed genotoxic effect levels (LOGELs) were observed for mitomycin-C at 4.8 µg/ml and methyl methanesulfonate (MMS) at 1750 µg/ml when applied topically to the skin surface. In-medium dosing with MMS produced a LOGEL of 20 µg/ml, which was very similar to the topical LOGEL when considering the total mass of MMS added. Comparisons between 3D medium and 2D LOGELs resulted in a 7-fold difference in total mass of MMS applied to each system, suggesting a protective function of the 3D microarchitecture. Interestingly, hydrogen peroxide (H2O2), a positive clastogen in 2D systems, tested negative in this assay. A non-genotoxic carcinogen, methyl carbamate, produced negative results, as expected. We also demonstrated expression of the DNA repair protein N-methylpurine-DNA glycosylase in EpiDerm™. Our preliminary validation here demonstrates that the RSMN assay may be a valuable follow-up to the current in vitro test battery, and together with its automation, could contribute to minimising unnecessary in vivo tests by reducing in vitro misleading positives.


Subject(s)
Micronucleus Tests/methods , Skin/drug effects , Skin/pathology , Automation , Carbamates/toxicity , Cell Line , DNA Glycosylases/genetics , Dose-Response Relationship, Drug , Gene Expression/drug effects , Humans , Hydrogen Peroxide/toxicity , Keratinocytes/drug effects , Keratinocytes/metabolism , Keratinocytes/pathology , Methyl Methanesulfonate/toxicity , Micronucleus Tests/statistics & numerical data , Mitomycin/toxicity , RNA, Messenger/genetics , RNA, Messenger/metabolism , Reproducibility of Results , Skin/metabolism , Tissue Culture Techniques/methods
12.
Mutat Res ; 719(1-2): 7-13, 2011 Feb 03.
Article in English | MEDLINE | ID: mdl-20951227

ABSTRACT

An integrated approach based on environmental and biological monitoring, including the analysis of biomarkers of exposure [excretion of S-phenylmercapturic acid (S-PMA)], early biological effects [micronucleus (MN) frequency] and susceptibility (genetic polymorphisms), was applied to characterize benzene exposure in a group of 70 traffic policemen and 40 employees of the city of Bologna, Italy. Median personal benzene exposure was 6.55-fold higher for traffic policemen than for controls (P<0.0001). This higher exposure was confirmed by a significant, 2.53-fold higher S-PMA excretion in traffic policemen compared with that observed for indoor workers (P<0.0001). Median MN frequency was also significantly higher in policemen compared with indoor workers (P=0.001), emphasizing the genotoxic effect potentially associated with benzene exposure. With regard to biomarkers of susceptibility, the analysis revealed that high epoxide hydrolase (mEH) (predicted) enzyme activity was significantly correlated with a lower median MN frequency (P=0.003). A gene-gender interaction was observed for the glutathione-S-transferase M1 (GSTM1) genotype. The GSTM1-null genotype was associated with a significantly higher median MN frequency in men, not in women. Statistical analysis did not reveal any association between the presence of the protective allele, pushing the pathway towards benzene detoxification, and MN frequency or S-PMA excretion. Even though there are some limitations in the study, our results indicate that policemen are exposed to higher levels of benzene than individuals spending most of the time indoors. This higher exposure may contribute to DNA damage, suggesting an increase health risk from traffic benzene emission. Finally, a more comprehensive study is warranted in order to better elucidate the involvement of EPHX1 genotypes combination in benzene genotoxicity.


Subject(s)
Benzene/analysis , Environmental Pollutants/analysis , Occupational Exposure/analysis , Police , Acetylcysteine/analogs & derivatives , Acetylcysteine/urine , Adult , Benzene/poisoning , Environmental Pollutants/poisoning , Epoxide Hydrolases/genetics , Epoxide Hydrolases/metabolism , Female , Genotype , Glutathione Transferase/genetics , Humans , Italy , Linear Models , Male , Micronuclei, Chromosome-Defective/chemically induced , Micronucleus Tests/statistics & numerical data , Middle Aged , Occupational Exposure/adverse effects , Polymorphism, Genetic , Risk Assessment/methods , Risk Assessment/statistics & numerical data , Risk Factors , Sex Factors , Young Adult
13.
Mutat Res ; 720(1-2): 42-52, 2011 Feb 28.
Article in English | MEDLINE | ID: mdl-21147256

ABSTRACT

The European Cosmetic Toiletry and Perfumery Association (COLIPA), along with contributions from the European Centre for the Validation of Alternative Methods (ECVAM), initiated a multi-lab international prevalidation project on the reconstructed skin micronucleus (RSMN) assay in EpiDerm™ for the assessment of the genotoxicity of dermally applied chemicals. The first step of this project was to standardize the protocol and transfer it to laboratories that had not performed the assay before. Here we describe in detail the protocol for the RSMN assay in EpiDerm™ and the harmonized guidelines for scoring, with an atlas of cell images. We also describe factors that can influence the performance of the assay. Use of these methods will help new laboratories to conduct the assay, thereby further increasing the database for this promising new in vitro genotoxicity test.


Subject(s)
Micronucleus Tests/methods , Skin Irritancy Tests/methods , Skin Irritancy Tests/standards , Guidelines as Topic , Humans , Micronucleus Tests/standards , Micronucleus Tests/statistics & numerical data , Mutagens/toxicity , Skin , Tissue Engineering/methods , Validation Studies as Topic
14.
Mutat Res ; 719(1-2): 35-40, 2011 Feb 03.
Article in English | MEDLINE | ID: mdl-21094274

ABSTRACT

3-Nitro-1,2,4-triazol-5-one (NTO) is an energetic explosive proposed for use in weapon systems, to reduce the sensitivity of warheads. In order to develop toxicity data for safety assessment, we investigated the genotoxicity of NTO, using a battery of genotoxicity tests, which included the Ames test, Chinese Hamster Ovary (CHO) cell chromosome aberration test, L5178Y TK(+/-) mouse lymphoma mutagenesis test and rat micronucleus test. NTO was not mutagenic in the Ames test or in Escherichia coli (WP2uvrA). NTO did not induce chromosomal aberrations in CHO cells, with or without metabolic activation. In the L5178Y TK(+/-) mouse lymphoma mutagenesis test, all of the NTO-treated cultures had mutant frequencies that were similar to the average frequencies of solvent control-treated cultures, indicating a negative result. Confirmatory tests for the three in vitro tests also produced negative results. The potential in vivo clastogenicity and aneugenicity of NTO was evaluated using the rat peripheral blood micronucleus test. NTO was administered by oral gavage to male and female Sprague-Dawley rats for 14 days at doses up to 2g/kg/day. Flow cytometric analysis of peripheral blood demonstrated no significant induction of micronucleated reticulocytes relative to the vehicle control (PEG-200). These studies reveal that NTO was not genotoxic in either in vitro or in vivo tests and suggest a low risk of genetic hazards associated with exposure.


Subject(s)
DNA Damage , Nitro Compounds/pharmacology , Triazoles/pharmacology , Animals , CHO Cells , Cell Line, Tumor , Cell Survival/drug effects , Chromosome Aberrations/drug effects , Cricetinae , Cricetulus , Female , Lymphoma/genetics , Lymphoma/pathology , Male , Mice , Micronucleus Tests/statistics & numerical data , Molecular Structure , Mutagenicity Tests , Mutation/drug effects , Nitro Compounds/chemistry , Nitro Compounds/toxicity , Rats , Rats, Sprague-Dawley , Reticulocytes/drug effects , Reticulocytes/metabolism , Risk Assessment/methods , Risk Assessment/statistics & numerical data , Risk Factors , Salmonella typhimurium/drug effects , Salmonella typhimurium/genetics , Triazoles/chemistry , Triazoles/toxicity
15.
Rev. bras. plantas med ; 12(4): 414-420, out.-dez. 2010. graf, tab
Article in Portuguese | LILACS | ID: lil-578981

ABSTRACT

A Tabebuia impetiginosa, conhecida popularmente como ipê-roxo, é uma planta nativa das florestas tropicais chuvosas da América do Sul e Central. Componentes químicos obtidos da casca têm mostrado efeito terapêutico, como antiinflamatório, antifúngico e antibacteriano. Porém, pela falta de dados na literatura, pouco se sabe sobre os efeitos do extrato das flores. Assim, o objetivo do presente trabalho foi avaliar o potencial mutagênico e antimutagênico do extrato obtido das flores da T. impetiginosa, em três diferentes concentrações (100, 300 e 500 mg kg-1 p.c.) pelo teste do micronúcleo. Para o teste de mutagenicidade, a doxorrubicina (DXR, 90 mg kg-1 p.c.) foi utilizada como indutor de danos no DNA e para o teste de antimutagenicidade, os tratamentos com o extrato foram realizados simultaneamente com este agente químico. O sangue periférico dos animais foi coletado 24 horas após os tratamentos. A comparação da frequência de eritrócitos policromáticos (PCEs) em 400 eritrócitos/animal entre os diferentes grupos não demonstrou qualquer citotoxicidade do extrato. Em relação às frequências de micronúcleos em PCEs (PCEMNs), não foram observadas diferenças significativas entre os grupos tratados com as diferentes concentrações de extrato e o controle negativo. Da mesma forma, todos os grupos de animais que receberam os tratamentos simultâneo do extrato (100, 300 ou 500 mg kg-1 p.c.) com a DXR, apresentaram valores de PCEMNs muito próximos quando comparados com os dados observados no grupo de animais que recebeu somente a DXR. Esses resultados apresentados indicam ausência de efeito mutagênico e antimutagênico do extrato obtido das flores da T. impetiginosa em sistema teste in vivo.


T. impetiginosa, known as "ipê-roxo", is a plant native to tropical rain forests of Central and South Americas. Chemical compounds obtained from its bark have shown anti-inflammatory, antifungal and antibacterial therapeutic effect. However, due to the lack of data in the literature, little is known about the effects of its flower extract. Thus, the aim of this study was to evaluate the mutagenic and antimutagenic potential of the extract obtained from T. impetiginosa flowers at three different concentrations (100, 300 and 500 mg kg-1 p.c.) by the micronucleus test. For the mutagenicity test, doxorubicin (DXR, 90 mg kg-1 p.c.) was used as DNA-damage inducer, while for the antimutagenicity test, treatments with the extract were performed simultaneously with this chemical agent. The peripheral blood of animals was collected 24 hours after the treatments. The frequency of polychromatic erythrocytes (PCEs) in 400 erythrocytes/animal was compared among the different groups and showed no extract cytotoxicity. As regards the frequency of micronuclei in PCEs (PCEMNs), there were no significant differences between the groups treated with different concentrations of extract and the negative control. Similarly, all groups of animals that received the simultaneous extract treatments (100, 300 or 500 mg kg-1 p.c.) with DXR showed very similar values of PCEMNs when compared with the data observed for the group of animals that received DXR alone. These results indicate no mutagenic and antimutagenic effect of the extract obtained from T. impetiginosa flowers in the testing system in vivo.


Subject(s)
Animals , Male , Rats , Antimutagenic Agents/analysis , Flowers , Mutagenicity Tests , Plant Extracts , Tabebuia , Analysis of Variance , Micronucleus Tests/statistics & numerical data
17.
Mutagenesis ; 24(5): 419-24, 2009 Sep.
Article in English | MEDLINE | ID: mdl-19567456

ABSTRACT

Although the rodent bone marrow micronucleus test has been in routine use for over 20 years, little work has been published to support its experimental design and all this has used the mouse rather than the rat. When it was decided to change the strain of rat routinely used in this laboratory to the Han Wistar, a preliminary study was performed to investigate the possible factors influencing experimental variability and to use statistical tools to examine possible study designs. Subsequently, a historical database comprising of vehicle controls accumulated from 65 studies was used to establish test acceptance criteria and a strategy for analysing equivocal results. The following conclusions were made: (i) no statistically significant differences were observed in experimental variability within or between control animals; although not statistically significant, the majority of experimental variability seen was found to be between separate counts on the same slide, with minimal differences found between duplicate slides from the same rat or between individual rats; (ii) power analyses showed that, if an equivocal result is obtained after scoring 2000 immature erythrocytes (IE), it is appropriate to re-code the slides and score an additional 4000 IE, i.e. analysing a total of 6000 IE; no meaningful increase in statistical power is gained by scoring >6000 IE; this is consistent with the variability observed between separate counts on the same slide; (iii) there was no significant difference between the control micronucleated immature erythrocyte (MIE) values at 24 and 48 h after dosing or between males and females; therefore, if an unusually low control value at either time point results in apparent small increases in MIE in a treated group, it is valid to pool control values from both time points for clarification and (iv) similar statistical power can be achieved by scoring 2000 IE from seven rats or 4000 IE from five rats, respectively. However, this is based only on control animals and does not consider possible differences in responses between animals to treatment with a potential genotoxin. In order to minimize the possible influence of responders and non-responders, the preferred study design in this laboratory is to score 2000 IE from groups of seven rats. Study data obtained over time confirmed observations made in the control study. Also from an ethical viewpoint, clarifying equivocal responses by combining control data from the 24- and 48-h time points and/or increasing the number of IE scored per animal has minimized the numbers of repeat studies necessary to determine the genotoxic status of a novel compound. However, before any laboratory can use these procedures, experimental data must be generated to demonstrate their validity.


Subject(s)
Bone Marrow/metabolism , Micronucleus Tests/methods , Micronucleus Tests/statistics & numerical data , Animals , Cell Count , Female , Male , Rats , Rats, Wistar , Reference Values , Reproducibility of Results , Sex Characteristics , Time Factors
18.
Cancer Biol Ther ; 8(18): 1719-21, 2009 Sep.
Article in English | MEDLINE | ID: mdl-19633420

ABSTRACT

BACKGROUND: Although the prognosis for malignant gliomas is normally dismal, it's not infrequent in neurooncologist's experience to find cases with unusually prolonged survival. In order to understand what factors influence survival of high grade glioma patients, a cohort of 196 high (III-IV) grade glioma patients was investigated for possible association between (1) survival and age at diagnosis; (2) survival and micronuclei in tumor tissue; (3) survival and gender; (4) micronuclei in tumor tissue and age at diagnosis. RESULTS: Patients diagnosed at an older age (>64 years) had a significantly higher hazard as compared to younger patients (

Subject(s)
Glioma/diagnosis , Glioma/genetics , Age Factors , Aged , Chromosomal Instability , Cohort Studies , Female , Humans , Italy , Kaplan-Meier Estimate , Male , Micronucleus Tests/statistics & numerical data , Middle Aged , Prognosis , Proportional Hazards Models
19.
Int Arch Occup Environ Health ; 82(2): 279-83, 2009 Jan.
Article in English | MEDLINE | ID: mdl-18481076

ABSTRACT

Genotoxic effects induced in vitro by the third generation mobile communication standard UMTS have recently been described by Schwarz et al. (Int Arch Occup Environ Health 81:755-767, 2008). These findings which may have considerable significance for environmental health have been commented upon by Lerchl (Int Arch Occup Environ Health in press, 2008) (this issue). These comments which are invalid in part have to be set right. Although some of his minor points are correct the objected inconsistencies are largely based on the author's incomplete and superficial consideration of published data in the field. Moreover, the statistical points being made cannot cast doubts on the validity of the experimental data reported by Schwarz et al. and may not change the principal conclusion of in vitro genotoxic action of UMTS signals.


Subject(s)
Cell Phone , Comet Assay/methods , Electromagnetic Fields/adverse effects , Fibroblasts/radiation effects , Lymphocytes/radiation effects , Micronuclei, Chromosome-Defective/radiation effects , Micronucleus Tests/methods , Animals , Bias , Cells, Cultured , Comet Assay/statistics & numerical data , Cricetinae , Cricetulus , DNA/radiation effects , DNA Damage , Data Interpretation, Statistical , Double-Blind Method , Humans , Micronuclei, Chromosome-Defective/statistics & numerical data , Micronucleus Tests/statistics & numerical data , Rats , Reproducibility of Results
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