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Articles by D. H Phillips
Total Records ( 4 ) for D. H Phillips
  S Zienolddiny , V Skaug , N. E Landvik , D Ryberg , D. H Phillips , R Houlston and A. Haugen
 

Genome-wide association studies have provided evidence that common variation at 5p15.33 [telomerase reverse transcriptase (TERT)-cleft lip and palate transmembrane 1-like (CLPTM1L)], 6p21.33 and 15q25.1 (CHRNA5-CHRNA3) influences lung cancer risk and cancer types with strong environmental risk factors. To independently validate these associations, we compared 5p15.33 (rs402710, rs401681), 6p21.33 (rs4324798) and 15q25.1 (rs1051730, rs16969968 and rs8034191) genotypes in 365 non-small cell lung cancer cases and 440 controls. Consistent with published data, variant genotypes of 5p15 (rs402710), 6p21 and 15q25 showed dose-dependent associations with lung cancer risk. To examine if variants influence the impact of environmental risk factors on lung carcinogenesis, we studied the relationship between genotype and levels of bulky aromatic/hydrophobic DNA adducts in lung tissue adjacent to tumor from 204 lung cancer cases. The risk allele of rs402710 (TERT-CLPTM1L locus) was associated with significantly higher levels of bulky aromatic/hydrophobic DNA adducts (P = 0.02). These data demonstrate a potential association between the TERT-CLPTM1L variant and levels of bulky DNA adducts measured by 32P-postlabeling and hence a basis for susceptibility to the development of lung cancer.

  D. A Eastmond , A Hartwig , D Anderson , W. A Anwar , M. C Cimino , I Dobrev , G. R Douglas , T Nohmi , D. H Phillips and C. Vickers
 

Since the publication of the International Programme on Chemical Safety (IPCS) Harmonized Scheme for Mutagenicity Testing, there have been a number of publications addressing test strategies for mutagenicity. Safety assessments of substances with regard to genotoxicity are generally based on a combination of tests to assess effects on three major end points of genetic damage associated with human disease: gene mutation, clastogenicity and aneuploidy. It is now clear from the results of international collaborative studies and the large databases that are currently available for the assays evaluated that no single assay can detect all genotoxic substances. The World Health Organization therefore decided to update the IPCS Harmonized Scheme for Mutagenicity Testing as part of the IPCS project on the Harmonization of Approaches to the Assessment of Risk from Exposure to Chemicals. The approach presented in this paper focuses on the identification of mutagens and genotoxic carcinogens. Selection of appropriate in vitro and in vivo tests as well as a strategy for germ cell testing are described.

  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.

 
 
 
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