Biomedical subjects

I Ceccherini

Publications and source records attributed to I Ceccherini.

58 records · Page 4Linked to original sources

PubMed1988

Kinetics of chromosomal aberrations and first mitosis division in human lymphocytes exposed to mitomycin C.

In order to understand the relationship between the chromosomal damage detectable at the first mitosis after mutagen treatment and the induced mitotic delay we studied the time pattern of both mitotic indices and chromosomal aberration frequencies in human lymphocytes treated in G1 with mitomycin C (2.5 microM) and cultured in vitro in the presence of 5-bromo-2'-deoxyuridine. Mitotic delay was observed in treated cells cultured for 81 h. At this point an increase in the frequency of chromosomal aberrations is evident and a higher proportion of abnormal cells enters mitosis, the long delay being due to the extensiveness of DNA damage. The importance of cell cycle progression for the detection of the maximal amount of induced chromosomal damage is discussed.

Cells, Cultured↗

PubMed1988

Caffeine post-treatment causes a shift in the chromosome aberration types induced by mitomycin C, suggesting a caffeine-sensitive mechanism of DNA repair in G2.

Human lymphocytes were exposed in G1 to mitomycin C (2.5 microM for 2 h) and harvested at 3-h intervals from 48 to 84 h after stimulation. All cultures were also post-treated in G2 with caffeine (2 mM). Different types of chromosomal aberrations were scored in the first division metaphases. Caffeine increases all chromosome aberration types by promoting a premature mitosis of damaged cells. However, when the frequency of damaged cells is not affected by the caffeine post-treatment, a reduction of the frequency of the exchange-type aberrations was shown. The possibility that caffeine interferes with some mechanism of G2 repair is discussed.

Caffeine↗

PubMed1986

Surveillance of birth defects: the Multicommunity Sets Technique tested by computer simulation.

Using a computer simulation for a series of births subject to various congenital malformations, the surveillance performance of the Multicommunity Sets Technique (MST) was compared to that of the Cumulative Sum Technique (CUSUM). Increases in malformation frequencies were simulated in (i) 6 out of 6 centres and (ii) only 3 out of 6 centres. MST was neither more sensitive nor more specific than CUSUM, and signalled increases with greater delay. One type of CUSUM procedure showed to accumulate more false alarms than MST in long periods of surveillance at the baseline malformation rate. The advantage of CUSUM was also shown for a single malformation with a very low baseline incidence, which according to Chen et al. (1983) should have been particularly suitable for MST surveillance.

Computer Simulation↗

PubMed1984

Human lymphocytes assay: cyclophosphamide metabolic activation by S9 system with low cytotoxicity.

The general suitability of exposing human lymphocytes directly to prolonged contact with an Ames-type microsomal (S9) activation system has been examined, for testing the effect of the indirect chemical mutagen, cyclophosphamide (CPA), on induction of chromosomal aberrations. Direct exposure of lymphocytes to only S9 mix produced a decrease in the mitotic index within 30-60 min, whereafter it stabilized at acceptable values. Further toxic effects following treatment with different doses of CPA and S9 mix, for the longest times of exposure were due to production of clastogenic metabolites. On the basis of these results, the low cytotoxicity of S9 mix in our conditions allows extension of the application of the test to the study of metabolites which require prolonged contact with the target cells.

Animals↗