1,721,202 research outputs found
Sister chromatid exchanges, chromosome aberrations and micronuclei in female lymphocytes: correlations with biological rhythms, miscarriages and contraceptive pill use
No full textOur study looked at the variation in peripheral blood lymphocytes, during the menstrual cycle, of frequencies of sister chromatid exchanges (SCE) and micronuclei (MN) in 819 women and cells with aberrant chromosomes (CA) in a selected sample of 136 volunteers. We observed significant fluctuations in SCE and CA frequencies: SCEs reached a maximum value at the end of menstruation and a low at the time of ovulation, whereas CAs showed a continuous increase from the beginning of the menstrual cycle up to the time of ovulation and a progressive decrease thereafter. MN frequency did not fluctuate in a statistically significant way. No statistically significant differences in SCE, CA and MN frequencies were observed when fertile women were compared with women taking the contraceptive pill or those in menopause and no difference was found between women who had undergone physiological or surgically induced menopause. Moreover, no difference was found between women with a history of miscarriages and matched controls. These data together suggest that the natural variations in sexual hormone levels, but not those due to the contraceptive pill or their reduction at menopause, can contribute in modulating the baseline frequencies of SCEs and CAs. Moreover, these data suggest that the increased risks either of producing a chromosome imbalance in the progeny (eliciting miscarriages) or of occurrence of gynaecological diseases is not predictable by evaluating cytogenetic end-points in peripheral blood lymphocytes
Mutagenicity of pesticides evaluated by means of gene conversion in Saccharomyces cerevisiae and in Aspergiullus nidulans.
No full textUse of three-way differential staining and liquid holding for the assessment of individual repair capacity
No full textMany studies on DNA repair mechanisms in mammalian cells have used liquid holding (LH) recovery to evaluate premutational damage repair. We used human peripheral lymphocytes (HPL) to assess damage reduction during the G0 phase. This technique was matched with the three-way differential (TWD) staining that allows identification of sister-chromatid exchanges (SCE) per cell cycle in third metaphases. By adopting this approach, the persistence of diepoxybutane (DEB)-induced lesions during subsequent cycles and individual repair capacity in LH conditions were measured. Our results show that most DEB-induced damage was repaired during the first cell cycle; a large part of lesions were removed during LH recovery, demonstrating G0 HPL repair capacity
Comparative studies on cytotoxic and genotoxic effects of two organic mercury compounds in lymphocytes and gastric mucosa cells of Sprague-Dawley rats
No full textHuman lymphocytes (HL) as well as lymphocytes (RL), hepatocytes (RH), and gastric mucosa cells (GM) of Sprague-Dawley rats were treated in vitro for 1 h with methylmercury chloride (MMC, 0.5-4 mug/ml) and dimethylmercury (DMM, 5-40 mug/ml). The cytotoxicity of the two organic mercury compounds was assessed by dye exclusion, and the extent of induced DNA fragmentation was measured with a single-cell microgel electrophoresis assay. Both MMC and DMM induced DNA damage and cytotoxicity in a dose-related manner in HL, RL, and GM. MMC was more effective in causing o significant increase in median DNA migration than DMM at doses yielding approximately the same degree of cytotoxicity. In rat hepatocytes the MMC-induced DNA damage was, however, lower than in the other cells. An analysis of repair kinetics following exposure to 2 mug/ml MMC was carried out in human lymphocytes obtained from an adult male donor. The bulk of DNA repair occurred 90 min after in vitro exposure, and it was about complete by 120 min following cessation of exposure. Finally, in order to have a basis for extrapolating to the human situation, in vivo studies were performed with Sprague-Dawley rats, also assessing the DNA damage and cytotoxicity in the lymphocytes and gastric mucosa cells. These in vivo results after oral exposure may be directly compared to the in vitro data obtained in the same cells
Use of the comet test in the evaluation of multidrug resistance of human cell lines
No full textThe comet test is a reported method for measuring DNA damage in individual mammalian cells, In the present report, the ability of this test to detect multidrug resistance (MDR) was evaluated. For this purpose, two human leukemia, well-characterized parental cell lines, HL60 and GEM, and their derived multidrug-resistant cells, HL60/DNR and CEM/VBL, were cultured with or without different anti-cancer agents. To evaluate the comet test, two DNA-damaging agents were used: daunorubicin (DNR), which is involved in MDR, and ambamustine (AMBA), which is independent from MDR. Moreover, in order to evaluate the specificity of the comet test, the activity of vinblastine (VBL), an MDR-related, DNA-independent anti-cancer drug, was also tested. Finally, the specificity of the comet test in detecting MDR was confirmed by culturing parental or resistant cells with DNR with or without the revertant agent verapamil (VER). Results confirm that the comet test is able to predict cellular chemoresistance when DNA damaging agents are tested. Finally, experiments on the role of the comet test in evaluating certain aspects of DNA repair are discussed
Alkaline versus Neutral Version of Comet Assay in Human Leukocytes Using 9 Compounds
No full textWe investigated the in vitro activity of 8 chemicals of pharmaceuticals and alimentary interest by using both the alkaline
and the neutral version of the Comet assay (Single Cell Gel Electrophoresis, SCGE). Aspirin (ASA), eugenol, (EUG),
paracetamol (PCM) quercitin (QRC) and saccarine (SAC) were chosen because contradictory results on their genotoxicity
have been reported in literature. Beside these, four compounds known to induce a wide range of genotoxic effects were
included: the aneuploigenic chemical colcemid (COLC), the DNA repair inhibitor caffeine (CAFF), and the crosslinking
inducer methylglyoxal (MTGL). Bleomycin (BLM) was used as positive control. The SCG test showed a good reproducibility
between replicated experiments and a good specificity. The contemporary use of the dual dye viability assay and the
neutral version of the Comet assay has allowed a better evaluation of the possible mechanism of action of the tested
compounds, with particular regard to cell toxicity, allowing to avoide false positive result
A mutagenicity methodology for assessing the formation of N-dimethylnitrosamine in vivo
No full textThe mutagenicity test methodology in vitro has been extensively used during recent years in the identification of potential carcinogenic agents. Mutagenic analyses have been applied to the study of chemical reaction products for the demonstration of the formation of mutagenic agents. Recent studies have indicated that secondary and tertiary amines, when reacted with nitrite in acidic conditions, yield N-nitroso compounds, including the potent carcinogen N-dimethylnitrosamine (NDMA). This finding raises the problem of risk evaluation of several food components of human diets for the presence of potential carcinogenic compounds. By combining a mutagenicity test procedure with yeast cells inoculated into the blood system of mice and incubated in the liver for various times (minutes or hours) we have devised a model methodology which allows the detection of the formation of N-dimethylnitrosamine (NDMA) at a level lower than 1 mg/kg. The methodology has been examined for its use in the study of activators of the nitrosation, such as thiocyanate, and of inhibitors of the nitrosation, such as ascorbic acid and tannic acid. Other food components of the human diet, such as red wine, have also been investigated by this methodology
ARE BASELINE FREQUENCIES OF SCEs, CAs AND MN IN HUMAN LYMPHOCYTES RELATED TO HEMATOLOGICAL VALUES?
No full textIn the present study, the correlation among several hematic values and the baseline frequencies of sister chromatid exchanges (SCEs), chromosome aberrations (CAs), and micronucleus (MN) were evaluated in human peripheral blood lymphocytes from a group of 1429 volunteers. Donors were selected to be representative of the general population of people living in the city of Pisa (Italy). By the use of the principal component analysis (PCA), principal components (PCs) were extracted from the complex pattern of correlations intrinsic in the hematic values (for example such as those among hemoglobin content, hematocrit, and erythrocyte count), and were tested for correlation on SCE, CA and MN frequencies. The seven PCs extracted (among 20 hematic values) were either positively or negatively correlated with the three cytogenetic endpoints. However, after correction by independent confounding factors (such as the age), with the use of the coefficient of partial correlation (CPC) analysis, only one PC significantly held the correlation with MN frequencies. This PC had the main contribution from the correlation between the concentration of potassium and the activity of alkaline phosphatase. These variables are known to be markers for bone (calcium) metabolism and are negatively correlated with MN frequencies. Because MN can arise from aneuploidy, the hematic concentrations of calcium may be important for stabilizing the mitotic process in stimulated lymphocytes. Finally, our study shows that the analysis of the hematic values adds very little information and removes a meaningless part of variance of the total variability observed for SCEs, CAs and MN
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