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C Tanzarella

Publications and source records attributed to C Tanzarella.

At least 55 records · Page 3Linked to original sources
PubMed1993

Cytokinesis-block micronucleus assay with kinetochore detection in colchicine-treated human fibroblasts.

A modified micronucleus assay using antikinetochore antibody has been developed in cytokinesis-blocked human fibroblasts as a simple method to identify aneuploidy-inducing agents. Different protocols for inducing binucleated cells by cytochalasin B in colchicine-treated human fibroblasts were investigated. A dose-related increase in kinetochore-positive micronuclei was obtained when cytochalasin B was given subsequent to colchicine treatment. No induction of micronuclei was observed in combined treatments of the two substances. These results indicate that the detection of kinetochores in micronucleated cytokinesis-blocked human fibroblasts can be effectively applied to the identification of environmental agents with aneuploidy-inducing potential. However, in testing such compounds particular attention should be paid to the protocol used for inducing cytokinesis-blocked cells.

Cell Division↗
PubMed1993

Hypersensitivity of lymphoblastoid lines derived from ataxia telangiectasia patients to the induction of chromosomal aberrations by etoposide (VP-16).

Mammalian DNA topoisomerase II represents the cellular target of many antitumor drugs, such as epipodophyllotoxin VP-16 (etoposide). The mechanism by which VP-16 exerts its cytotoxic and antineoplastic actions has not yet been firmly established, although the unique correlation between sensitivity to ionizing radiation and to topoisomerase II inhibitors suggest the involvement of DNA double-strand breaks. In the present study we analyzed the chromosomal sensitivity of lymphoblastoid cell lines derived from ataxia telangiectasia (AT) patients to low concentrations of the drug. Our results indicate that AT derived cells are hypersensitive to the clastogenic activity of VP-16 either when the drug is present for the whole duration of the cell cycle or specifically in the G2 phase, confirming that the induction of DNA double strand breaks, to which AT cells seem typically sensitive, could have an important role in the biological activity of VP-16.

Ataxia Telangiectasia↗
PubMed1993

Sensitivity of lymphocytes from vulcanizers to the in vitro induction of sister chromatid exchanges.

Spontaneous frequencies of sister chromatid exchanges (SCEs) and SCEs induced in vitro by chemicals with different mechanisms of action such as mitomycin C, 4-nitroquinoline oxide, and 3-aminobenzamide were examined in phytohemagglutinin-stimulated peripheral blood lymphocytes from a group of workers in a rubber plant and a control group, both of which had been analyzed for levels of spontaneous SCEs 2 years earlier. An interindividual variability in the induction of SCEs was found after in vitro treatments with the different mutagens, which did not correlate with occupational exposure. This variability in the sensitivity to the induction of SCEs might be correlated to genetic differences among individuals, which have to be taken into account in environmental monitoring programs.

Adult↗
PubMed1992

Chromosomal aberrations in human lymphocytes induced in vitro by very low doses of X-rays.

This paper presents results of a collaborative experiment between six laboratories which examined the yields of unstable chromosomal aberrations in human lymphocytes induced in vitro by X-rays over the dose range 0-300 mGy. The work included data points of nominal doses of 0, 3, 5, 6, 10, 20, 30, 50 and 300 mGy. Cells from 24 donors were examined and a total of about 300,000 metaphases were scored. The work was undertaken to determine the limits of sensitivity of the system taking into account variations in scoring data due to inter-donor sample and inter-laboratory effects. Despite the existence of these effects, aberration yields significantly in excess of control values were seen at doses greater than 20 mGy and these were consistent with a linear extrapolation from higher doses. Below 20 mGy the observed dicentric yields were generally lower than background, but not significantly so. Excess acentric aberrations, on the other hand, and centric rings, were higher than the controls but the increase was usually not significant. It is concluded that the statistical uncertainties are such that below 20 mGy this technique cannot distinguish between a linear or a threshold model.

Chromosome Aberrations↗
PubMed1992

The yield of fission neutron-induced chromatid aberrations in G2-stage human lymphocytes: effect of caffeine, hydroxyurea and cytosine arabinoside post-irradiation.

To evaluate the influence of inhibitors of DNA synthesis/repair on the yield of chromosomal aberrations in the G2 phase of the cell cycle, whole-blood cultures of human lymphocytes were exposed to various doses of fission neutrons or X-rays and treated post-irradiation during the last 2.45 h before harvesting, with 5 mM caffeine, 5 mM hydroxyurea (HU) and 0.05 mM cytosine arabinoside (ara-C). The presence of caffeine and HU strongly potentiated the yield of chromatid-type aberrations induced by both neutrons and X-rays. No potentiating effect, except at the highest dose of neutrons, was observed when irradiated cells were subsequently treated with ara-C. Since ara-C strongly potentiated the frequency of chromatid aberrations induced in G2 lymphocytes by X-rays, the results presented here indicate that fission neutrons produce a smaller proportion of lesions, the repair of which can be inhibited by ara-C, compared with the number produced by X-rays. In addition, neutron-induced mitotic delay was shortened by treatment with caffeine, mainly within the first 2 h after irradiation.

Caffeine↗
PubMed1992

A collaborative study on the improvement of the micronucleus test in cultured human lymphocytes.

A collaborative study between two laboratories has been carried out in order to investigate the reproducibility of the cytokinesis-block micronucleus assay in human lymphocytes. A modified protocol to obtain good quality slides from whole blood cultures has been developed. The spontaneous frequencies of micronuclei in binucleated lymphocytes from five male subjects were evaluated in each laboratory at two cytochalasin-B concentrations (3 and 6 micrograms/ml). Our data show that 6 micrograms/ml cytochalasin-B was more effective than 3 micrograms/ml to arrest cytokinesis in all the donors analysed. The mean frequency of micronuclei in binucleated cells was significantly lower at 6 micrograms/ml compared to 3 micrograms/ml cytochalasin-B in both laboratories. The results obtained indicate a very high concordance between both sets of data supporting the validity of the proposed protocol.

Adult↗
PubMed1991

In vitro micronucleus test with kinetochore staining: evaluation of test performance.

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.

Aneuploidy↗
PubMed1989

Indirect mitotic nondisjunction in Vicia faba and Chinese hamster cells.

The hypothesis of indirect mitotic nondisjunction was tested in plant and mammalian cells. This hypothesis states that micronuclei derived from lagging chromosomes or chromatids are able to perform DNA synthesis and undergo mitotic condensation synchronously with main nuclei. Hence, as chromosomes, they can be moved to spindle poles together with the chromosomes of the main nuclei during mitosis. In that way chromosomes "lost" as micronuclei can be reincorporated in the main nuclei. In order to test this, both Vicia faba meristematic cells and cells of a Chinese hamster line (Cl-1) were treated with low doses of colchicine. Mitotic anomalies, micronuclei and cells with a polyploid or aneuploid karyotype were scored at different fixation times. A detailed analysis was performed on single chromosome misdistributions, as well as on micronuclei and cells with aneuploid karyotypes derived from single chromosome misdistributions. Indirect mitotic nondisjunction was shown to play a primary role in the origin of aneuploid karyotypes in Vicia faba, but not in Cl-1 cells.

Animals↗
PubMed1989

Induction of chromosomal aberrations and SCE by camptothecin, an inhibitor of mammalian topoisomerase I.

The induction of chromosomal aberrations and sister-chromatid exchanges (SCE) was studied in human lymphocyte cultures treated with camptothecin (CM), an inhibitor of mammalian topoisomerase I. While no chromosome-type aberrations were found in G1-treated cells, instead there was a dose-dependent induction of chromatid-type aberrations. These types of chromosomal alteration were not induced during the treatment itself but during the S phase, as CM is not efficiently removed with the normal washing procedure after treatment.

Camptothecin↗
PubMed1988

Immunofluorescent staining of kinetochores in micronuclei: a new assay for the detection of aneuploidy.

The immunofluorescent staining of kinetochores in micronuclei with antikinetochore antibodies was used to develop an in vitro assay for aneuploidy-inducing agents. The results show that about 80% of micronuclei induced by either colchicine or chloral hydrate contained kinetochores; only 9% of X-ray-induced micronuclei reacted positively to the antibody. These findings indicate that the in vitro micronucleus assay coupled with immunofluorescent staining of kinetochores can be a useful method for assessing the ability of chemicals to induce aneuploidy and/or chromosome aberrations.

Aneuploidy↗
PubMed1988

Frequencies of chromosomal aberrations induced in human blood lymphocytes by low doses of X-rays.

The dose-response for radiation-induced chromosome aberrations in human lymphocytes is usually fitted to the quadratic model. This assumes that the slope is essentially linear at low doses. Empirical observations of linearity at less than 200 mGy are, however, sparse. Some data have been published indicating a non-linear (threshold) response and these are reviewed. In particular one study with X-rays showed a plateau in response up to 50 mGy and with a significant dip below the control level at 4 mGy. The mechanism proposed to explain non-linearity is that low doses stimulate the enzymic repair capability of lymphocytes. Preliminary data are presented from a large experiment by six laboratories in which the low dose-response for X-rays has been re-examined. The plateau in the dose-response relationship, if it exists, does not extend to doses above approximately 10 mGy. No irradiated cells yielded aberration levels significantly below the control. Over the range 0-300 mGy the response can be fitted to a linear regression. There are, however, variations in sensitivity between cells from different donors. An unexpected finding was that some lymphocytes contained greater than 1 exchange aberrations. This may indicate a small subset of cells that are especially susceptible to the induction of aberrations by low doses.

Adult↗
PubMed1986

Effect of post-treatments with caffeine during G2 on the frequencies of chromosome-type aberrations produced by X-rays in human lymphocytes during G0 and G1.

Human lymphocytes were irradiated with X-rays in G0 and G1, grown in the presence of 5-bromodeoxyuridine, and harvested at different times from 48 to 80 h after stimulation. Some cultures were exposed to 2.5-5 mM caffeine during the last 3 h before harvesting. The frequencies of chromosome-type aberrations were scored in first division (M1) metaphases. The post-treatment with caffeine increased the frequencies of mitoses and chromosome-type aberrations in irradiated cultures. The results suggest that cells carrying chromosome-type aberrations are delayed in G2 and that caffeine increases the frequencies of aberrations in dividing cells by removing this G2-block.

Caffeine↗
PubMed1984

Influence of caffeine and 3-aminobenzamide in G2 on the frequency of chromosomal aberrations induced by thiotepa, mitomycin C and N-methyl-N-nitro-N'-nitrosoguanidine in human lymphocytes.

The effects of post-treatments with caffeine in G2 on the frequency of chromosomal aberrations induced by thiotepa, mitomycin C and N-methyl-N-nitro-N'-nitrosoguanidine were studied in human lymphocytes. Caffeine was found to potentiate the frequency of chromatid aberrations induced by all 3 S-dependent agents tested; the most striking enhancement being obtained when caffeine was present during the last 1.5 h before harvesting. Post-treatments in G2 with 3-aminobenzamide had no influence on the aberration frequency induced by thiotepa and N-methyl-N-nitro-N'-nitrosoguanidine.

Benzamides↗
PubMed1984

Effect of caffeine on induced damage in cells of Xenopus laevis.

Xenopus laevis cells were treated with mitomycin C and subsequently treated with caffeine during either the S- or G2-phase of the cell cycle. The frequency of induced chromatid exchanges was especially increased by caffeine posttreatment during the S-phase. This increase took place at the expense of the frequency of isochromatid breaks, which was reduced, both when the caffeine posttreatment was given during the S- and G2-phase.

Animals↗
PubMed1984

Effect of L-ethionine on spontaneous and MMC-induced SCEs in G0 and G1 human lymphocytes under liquid-holding recovery conditions.

L-Ethionine is an ethyl analogue of the amino acid, methionine, well known as a carcinogen but not as a mutagen. Its activity is clearly related to its capacity to hypomethylate DNA and RNA. At a final concentration of 5 mM, L-ethionine completely inhibits DNA synthesis in PHA-stimulated human lymphocytes, probably acting on a methylation reaction critical for the initiation of the S phase. This block can be reversed. Utilizing this capacity of L-ethionine to block cell proliferation, we have studied the influence of G0 and G1 repair of premutational damage (PMD) (equivalent to liquid-holding recovery in bacteria) on spontaneous and MMC-induced SCEs in human lymphocytes. Our results clearly show that L-ethionine in our experimental conditions significantly increases the frequencies of spontaneous and MMC-induced SCEs. In view of the hypomethylating activity of the analogue, we hypothesize that this action at the replication fork level may increase the error-prone ligation of unrepaired lesions, thus influencing the frequency of occurrence of SCEs.

Antibiotics, Antineoplastic↗
PubMed1984

Biological monitoring of workers in the rubber industry. I. Chromosomal aberrations and sister-chromatid exchanges in lymphocytes of vulcanizers.

To evaluate the possible genetic consequences of the industrial exposure among the vulcanizers of a rubber plant we measured the in vivo levels of chromosomal aberrations and sister-chromatid exchanges in peripheral lymphocytes of 34 vulcanizers and in an adequate control population. The observed chromosomal aberration frequencies were 1.9 +/- 1.4 aberrations/100 cells in the exposed group and 2.1 +/- 1.5 aberrations/100 cells in the controls. No difference was found between the two groups for the mean value of sister-chromatid exchanges (5.2 +/- 1.3 in the exposed, 5.2 +/- 0.7 in the control group). Cigarette-smoking was clearly associated with increased sister-chromatid exchange frequencies both in the exposed and in the control groups, while chromosomal aberration frequencies were not correlated with smoking habits.

Chromosome Aberrations↗