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Articles by J. P Teixeira
Total Records ( 2 ) for J. P Teixeira
  L Forchhammer , C Johansson , S Loft , L Moller , R. W. L Godschalk , S. A. S Langie , G. D. D Jones , R. W. L Kwok , A. R Collins , A Azqueta , D. H Phillips , O Sozeri , M Stepnik , J Palus , U Vogel , H Wallin , M. N Routledge , C Handforth , A Allione , G Matullo , J. P Teixeira , S Costa , P Riso , M Porrini and P. Moller

The comet assay has become a popular method for the assessment of DNA damage in biomonitoring studies and genetic toxicology. However, few studies have addressed the issue of the noted inter-laboratory variability of DNA damage measured by the comet assay. In this study, 12 laboratories analysed the level of DNA damage in monocyte-derived THP-1 cells by either visual classification or computer-aided image analysis of pre-made slides, coded cryopreserved samples of cells and reference standard cells (calibration curve samples). The reference standard samples were irradiated with ionizing radiation (0–10 Gy) and used to construct a calibration curve to calculate the number of lesions per 106 base pair. All laboratories detected dose–response relationships in the coded samples irradiated with ionizing radiation (1.5–7 Gy), but there were overt differences in the level of DNA damage reported by the different laboratories as evidenced by an inter-laboratory coefficient of variation (CV) of 47%. Adjustment of the primary comet assay end points by a calibration curve prepared in each laboratory reduced the CV to 28%, a statistically significant reduction (P < 0.05, Levene's test). A large fraction of the inter-laboratory variation originated from differences in image analysis, whereas the intra-laboratory variation was considerably smaller than the variation between laboratories. In summary, adjustment of primary comet assay results by reference standards reduces inter-laboratory variation in the level of DNA damage measured by the alkaline version of the comet assay.

  J. P Teixeira , J Gaspar , P Coelho , C Costa , S Pinho Silva , S Costa , S Da Silva , B Laffon , E Pasaro , J Rueff and P. Farmer

Styrene is a commercially important chemical widely used in the manufacture of synthetic rubber, resins, polyesters and plastics. The highest levels of human exposure to styrene occur during the production of reinforced plastic products. The objective of this work was to evaluate both DNA and cytogenetic damage in styrene-exposed workers, analysing only non-smoker individuals. Environmental levels of styrene and urinary concentrations of mandelic and phenylglyoxylic acids were determined, and genetic damage was studied by means of micronucleus (MN) test, sister chromatid exchanges (SCEs) and comet assay. Fifty-two fibreglass-reinforced plastics workers and 54 controls took part in the study. The mean air concentration of styrene in the breathing zone of workers exceeded the threshold limit value, and 24 workers exceeded the biological exposure index. A strong and significant correlation was found between styrene environmental concentrations and urinary metabolites. Higher SCE rate (P < 0.01) was observed in exposed workers than in controls. Besides, significant correlations were obtained for SCE rate with both environmental and internal exposure parameters (r = 0.496, P < 0.01 and r = 0.511, P < 0.01, respectively). Results from MN test and comet assay showed slight and non-significant increases related to the exposure. Our data seem to support previous studies reporting genotoxicity associated with occupational exposure to styrene, excluding the confounding influence of smoking, although caution must be taken in the interpretation of these results since the significance of an increase in SCE rate is still unclear.

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