Search PubMed⌕ Search

Biomedical subjects

J M Parry

Publications and source records attributed to J M Parry.

195 records · Page 11Linked to original sources
PubMedDate not supplied

An assay for mutagenic activity of 4CMB, 4HMB and BC, using the "microtitre" fluctuation test.

4CMB, 4HMB and BC were assayed for mutagenic activity using the 'microtitre' bacterial fluctuation test without metabolic activation. 4CMB was positive in strains of Salmonella typhimurium detecting both base-substitution and frameshift mutation. BC was weakly positive only in the strain which detects base-substitution mutation. 4HMB was negative in both strains. 4CMB and 4HMB were equally toxic to the strains, whilst BC was comparatively less toxic.

Benzyl Compounds↗
PubMedDate not supplied

A comparison of the response to 4CMB, 4HMB and BC of 5 yeast strains differing in their radiosensitivities.

The test compounds 4CMB, 4HMB and BC were assayed for their genotoxicity using stationary phase cultures of 5 yeast strains which differ in their mutagen sensitivity. It was found that 4HMB produced no differences in survival between the 5 strains whereas 4CMB and BC caused more lethality in the triple red strain than the other 4 strains. The results indicate that both BC and 4CMB are capable of inducing DNA damage which results in cell lethality in the repair-deficient triple mutant.

Benzyl Compounds↗
PubMedDate not supplied

The activity of 4CMB, 4HMB and BC in Saccharomyces cerevisiae JD1.

3 structurally related compounds, 4-chloromethylbiphenyl (4CMB), 4-hydroxymethylbiphenyl (4HMB), and benzyl chloride (BC) were assayed for their ability to induce mitotic gene conversion in stationary phase cultures of the yeast, Saccharomyces cerevisiae JD1. This strain allows gene conversion to be scored at 2 independent loci, trp 5 and his 4. The results reported in this paper indicate that both 4CMB and BC are genetically active in yeast, producing dose-related increases in mitotic gene conversion at both the loci tested; 4HMB showed no such activity. At high survival levels 4CMB and BC showed comparable activity. However, as toxicity increased BC showed much more potent convertogenic activity, whereas with 4CMB a reduction in induced gene conversion was observed. The presence of a microsomal activation system derived from the livers of Aroclor-induced male rats did not significantly affect the activity of any of the compounds.

Animals↗
PubMedDate not supplied

The equivalence of assays within individual guidelines for the testing of the potential mutagenicity of chemicals: problems associated with battery selection.

Many individual Mutagenicity Guidelines contain suggested test systems with choices of such parameters as strains, cell types and even endpoint assayed. Comparisons have been made of data obtained from variants of yeast assays for the induction of mitotic recombination, in vitro assays for the induction of chromosome aberrations and assays for the induction of cell transformation. Individual test variants included in guidelines of the EEC and OECD show considerable qualitative and quantitative variability of response to potential mutagens and carcinogens. Such variability between assays within the same guideline raises considerable problems in the selection of test batteries chosen from published Mutagenicity Guidelines. Improved battery selection is dependent upon the reduction of choice within guidelines to those assays which produce consistent and reproducible results.

Animals↗
PubMedDate not supplied

The clastogenic activity of 1,6-dinitropyrene in peripheral human lymphocytes.

The ability of 1,6-dinitropyrene to induce chromosome damage in peripheral human lymphocyte cultures has been demonstrated. Low levels of clastogenic activity were detected following 3-h treatments with 1,6-dinitropyrene in the presence of a rat-liver cytosol fraction. The clastogenic activity reached a peak at a concentration of 1.25 micrograms/ml of 1,6-dinitropyrene after which the frequency of aberrations decreased. This unusual genotoxic dose response is similar to that found previously in yeast and rat-liver cells. The fact that a positive result was obtained using human lymphocytes shows that, in the presence of the appropriate activation system, dinitropyrene is genotoxic in human cells.

Chromosomes↗
PubMedDate not supplied

Molecular analysis of the chemoprotective effects of topical sunscreen and vitamin C in preventing UV-induced and reactive oxygen species-induced DNA damage, respectively, using the PCR inhibition methodology.

BACKGROUND: We have developed a PCR-based technique which has previously been shown to be capable of detecting DNA damage (Adducts, strand breaks) induced by carcinogens. We wanted to explore the possibility of detecting anti-carcinogens with this methodology through a corresponding reduction in DNA damage induction. MATERIALS AND METHODS: We have used a PCR-based system which relies on the fact that Taq polymerase cannot amplify damaged DNA efficiently. We immobilised DNA in microtitre plates and exposed them to UV-B light and hydrogen peroxide. In addition, we tested the capacity of sunscreens and ascorbate (vitamin C) to ameliorate the DNA damage caused by UV-B and hydrogen peroxide, respectively. RESULTS: We have shown that in the case of UV-B, sunscreens can effectively reduce the amount of DNA damage induced. This appears to be dependent upon the Sun Protection Factor of the sunscreen, with SPF 35 sunscreens protecting DNA particularly well. We found that both hydrogen peroxide and ascorbate were capable, at high doses, of inducing DNA damage. When mixed, ascorbate effectively increased the DNA damaging effect of hydrogen peroxide. CONCLUSION: We have shown that the PCR inhibition method may be suitable for untangling the complex carcinogenic/anticarcinogenic aspects of factors in the diet and environment. However, the DNA damaging effect of ascorbate must be viewed in the context of the high concentrations used here.

Animals↗