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Articles by G Matullo
Total Records ( 3 ) for G Matullo
  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.

  C Johansson , P Moller , L Forchhammer , S Loft , R. W. L Godschalk , S. A. S Langie , S Lumeij , G. D. D Jones , R. W. L Kwok , A Azqueta , D. H Phillips , O Sozeri , M. N Routledge , A. J Charlton , P Riso , M Porrini , A Allione , G Matullo , J Palus , M Stepnik , A. R Collins and L. Moller
 

The increasing use of single cell gel electrophoresis (the comet assay) highlights its popularity as a method for detecting DNA damage, including the use of enzymes for assessment of oxidatively damaged DNA. However, comparison of DNA damage levels between laboratories can be difficult due to differences in assay protocols (e.g. lysis conditions, enzyme treatment, the duration of the alkaline treatment and electrophoresis) and in the end points used for reporting results (e.g. %DNA in tail, arbitrary units, tail moment and tail length). One way to facilitate comparisons is to convert primary comet assay end points to number of lesions/106 bp by calibration with ionizing radiation. The aim of this study was to investigate the inter-laboratory variation in assessment of oxidatively damaged DNA by the comet assay in terms of oxidized purines converted to strand breaks with formamidopyrimidine DNA glycosylase (FPG). Coded samples with DNA oxidation damage induced by treatment with different concentrations of photosensitizer (Ro 19-8022) plus light and calibration samples irradiated with ionizing radiation were distributed to the 10 participating laboratories to measure DNA damage using their own comet assay protocols. Nine of 10 laboratories reported the same ranking of the level of damage in the coded samples. The variation in assessment of oxidatively damaged DNA was largely due to differences in protocols. After conversion of the data to lesions/106 bp using laboratory-specific calibration curves, the variation between the laboratories was reduced. The contribution of the concentration of photosensitizer to the variation in net FPG-sensitive sites increased from 49 to 73%, whereas the inter-laboratory variation decreased. The participating laboratories were successful in finding a dose–response of oxidatively damaged DNA in coded samples, but there remains a need to standardize the protocols to enable direct comparisons between laboratories.

  D Palli , S Polidoro , M D'Errico , C Saieva , S Guarrera , A. S Calcagnile , F Sera , A Allione , S Gemma , I Zanna , A Filomena , E Testai , S Caini , R Moretti , M. J Gomez Miguel , G Nesi , I Luzzi , L Ottini , G Masala , G Matullo and E. Dogliotti
 

Risk factors for gastric cancer (GC) include inter-individual variability in the inflammatory response to Helicobacter pylori infection, in the ability of detoxifying DNA reactive species and repairing DNA damage generated by oxidative stress and dietary carcinogens. To evaluate the association between polymorphic DNA repair genes and GC risk, a case–control study including 314 histologically confirmed GC patients and 548 healthy controls was conducted in a GC high-risk area in Tuscany, Italy. Polymorphic variants of base excision repair (APE1-D148E, XRCC1-R194W, XRCC1-R399Q and OGG1-S326C), nucleotide excision repair (XPC-PAT, XPA-23G>A, ERCC1-19007T>C and XPD-L751Q), recombination (XRCC3-T241M) and alkylation damage reversal (MGMT-L84F) were tested for their potential role in the development of GC by using logistic regression models. The same population was also characterised for GSTT1 and GSTM1 variant alleles to search for possible functional interactions between metabolic and DNA repair genotypes by two-way interactions using multivariate logistic models. No significant association between any single DNA repair genotype and GC risk was detected with a borderline association with the XPC-PAT homozygous genotype [odds ratio (OR) = 1.42; 95% confidence interval (CI) 0.94–2.17]. Gene–gene interaction analysis revealed combinations of unfavourable genotypes involving either multiple DNA repair polymorphisms or DNA repair and GST-specific genotypes. The combination of the XPC-PAT and the XPA variant alleles significantly increased GC risk (OR = 2.15; 95% CI 1.17–3.93, P = 0.0092). A significant interaction was also found between the APE1 wild-type genotype and either the single GSTT1 (OR = 4.90; 95% CI 2.38–10.11, P = 0.0079) or double GSTM1-GSTT1 null (OR = 7.84; 95% CI 3.19–19.22, P = 0.0169) genotypes or the XPA-mutant allele (OR = 3.56; 95% CI 1.53–8.25, P = 0.0012). These findings indicate that a complex interaction between host factors such as oxidative stress, antioxidant capacity and efficiency of multiple DNA repair pathways underlies the inter-individual variability in GC risk.

 
 
 
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