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B Tierney

Publications and source records attributed to B Tierney.

At least 37 records · Page 2Linked to original sources
PubMed1979

Biological activities of dihydrodiols derived from two polycyclic hydrocarbons in rodent test systems.

Comparisons have been made between (a) the initiation of tumours in mouse skin, (b) the induction of hyperplasia and the suppression of sebaceous glands in mouse skin and (c) the induction of s.c. tumours in rats, by either benzo[a]pyrene or 7-methylbenz[a]anthracene and their related K-region and non-K-region dihydrodiols. Whilst the 3,4-dihydrodiol derived from 7-methylbenz[a]anthracene is more active than the hydrocarbon in initiating tumours in mouse skin (subsequently promoted by a phorbol ester) the 7,8-dihydrodiol of benzo[a]pyrene is very much less active than benzo[a]pyrene itself in the induction of hyperplasia or the suppression of sebaceous glands in mouse skin or in the induction of s.c. sarcomas in rats. Since much other evidence suggests that the 3,4-dihydrodiol of 7-methylbenz[a]anthracene and the 7,8-dihydrodiol of benzo[a]pyrene are the dihydrodiols involved, via the related vicinal diol-epoxides, in the metabolic activation of these hydrocarbons, mouse skin initiation-promotion experiments may be more useful for the identification of such diols than the other two in vivo tests for biological activity used here.

Animals↗
PubMed1979

Comparison of mutagenesis and malignant transformation by dihydrodiols from benz[a]anthracene and 7,12-dimethylbenz[a]anthracene.

Five dihydrodiols derived from benz[a]anthracene (BA) and 4 dihydrodiols derived from 7,12-dimethylbenz[a]anthracene (DMBA) have been tested, together with the parent hydrocarbons, for their abilities to induce mutations to 8-azaguanine resistance in V79 (Chinese hamster cells and malignant transformation in M2 mouse fibroblasts. The syn- and anti-isomers of benz[a]anthracene 8,9-diol 10,11-oxide were also tested for biological activity in these two systems. The non-K-region 1,2- and 3,4-dihydrodiols of BA induced mutations but the non-K-region 8,9-dihydrodiol and the K-region 5,6-dihydrodiol were inactive as mutagens; none of these BA diols transformed M2 mouse fibroblasts. The 3,4- and the 8,9-dihydrodiols derived from 7,12-dimethylbenz[a]anthracene induced mutations in V79 cells and malignant transformation in M2 mouse fibroblasts and both were more active than the hydrocarbon itself. The K-region 5,6-dihydrodiol and the non-K-region 10,11-dihydrodiol of DMBA were inactive in both test systems. The results are not inconsistent with other data suggesting that the metabolic activation of both BA and DMBA occurs through conversion of the respective 3,4-dihydrodiols into the related vicinal diol-epoxides, although other dihydrodiols may also be involved in vivo. Both the BA diol-epoxides tested were mutagenic, but although the anti-isomer transformed M2 fibroblasts, the syn-isomer was inactive.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1978

The formation of dihydrodiols by the chemical or enzymic oxidation of benz[a] anthracene and 7,12-dimethylbenz[a] anthracene.

When benz[a] anthracene was oxidised in a reaction mixture containing ascorbic acid, ferrous sulphate and EDTA, the non-K-region dihydrodiols, trans-1,2-dihydro-1,2-dihydroxybenz[a] anthracene and trans-3,4-dihydro-3,4-dihydroxybenz[a] anthracene together with small amounts of the 8,9- and 10,11-dihydrodiols were formed. When oxidised in a similar system, 7,12-dimethylbenz[a] anthracene yielded the K-region dihydrodiol, trans-5,6-dihydro-5,6-dihydroxy-7,12-dimethylbenz[a] anthracene and the non-K-region dihydrodiols, trans-3,4-dihydro-3,4-dihydroxy-7,12-dimethylbenz[a] anthracene, trans-8,9-dihydro-8,9-dihydroxy-7,12-dimethylbenz[a] anthracene, trans-10,11-dihydro-10,11-dihydroxy-7,12-dimethylbenz[a] anthracene and a trace of the 1,2-dihydrodiol. The structures and sterochemistry of the dihydrodiols were established by comparisons of their UV spectra and chromatographic characteristics using HPLC with those of authentic compounds or, when no authentic compounds were available, by UV, NMR and mass spectral analysis. An examination by HPLC of the dihydrodiols formed in the metabolism, by rat-liver microsomal fractions, of benz[a] anthracene and 7,12-dimethylbenz[a] anthracene was carried out. The metabolic dihydriols were identified by comparisons of their chromatographic and UV or fluorescence spectral characteristics with compounds of known structures. The principle metabolic dihydriols formed from both benz[a] anthracene and 7,12-dimethylbenz[a] anthracene were the trans-5,6- and trans-8,9-dihydrodiols. The 1,2- and 10,11-dihydrodiols were identified as minor products of the metabolism of benz [a] anthracene and the tentative identification of the trans-3,4-dihydriol as a metabolite was made from fluorescence and chromatographic data. The minor metabolic dihydriols formed from 7,12-dimethylbenz[a] anthracene were the trans-3,4-dihydrodiol and the trans-10,11-dihydriol but the trans-1,2-dihydrodiol was not detected in the present study.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1978

The preparation of dihydrodiols from 7-methylbenz[a]-anthracene.

The products formed when the carcinogenic polycyclic hydrocarbon 7-methylbenz[a] anthracene is oxidized with an ascorbic acid-ferrous sulphate mixture have been investigated. All 5 possible dihydrodiols were formed and the isolation of the 3 non-K-region dihydrodiols, trans-1,2-dihydro-1,2-dihydroxy-7-methylbenz[a]anthracene, trans-3,4-dihydro-3,4-dihydroxy-7-methylbenz[a] anthracene and trans-8,9-dihydro-8,9-dihydroxy-7-methylbenz[a] anthracene is described. The purification of the dihydrodiols was carried out by thin-layer (TLC) followed by preparative high pressure liquid chromatography (HPLC). The ultra-violet, spectral and nuclear magnetic resonance (NMR) characteristics of the dihydrodiols are reported and the data used to assign the proposed structures. An explanation for the unusual preferred conformation which the 8,9-dihydrodiol adopts is advanced.

Animals↗
PubMed1978

The formation of dihydrodiols by chemical or enzymic oxidation of 3-methylcholanthrene.

The chemical oxidation of 3-methylcholanthrene in an ascorbic acid-ferrous sulphate-EDTA reaction mixture gave all five possible dihydrodiols. The structures and stereochemistry of the dihydrodiols were shown by UV, mass and NMR spectral studies and by chemical examination to be cis-2a,3-dihydroxy-3-methylcholanthrene, trans-4,5-dihydro-4,5-dihydroxy-3-methylcholanthrene, trans-7,8-dihydro-7,8-dihydroxy-3-methylcholanthrene, trans-9,10-dihydro-9,10-dihydroxy-3-methylcholanthrene, cis-11,12-dihydro-11,12-dihydroxy-3-methylcholanthrene and trans-11,12-dihydro-11,12-dihydroxy-3-methylcholanthrene. An examination by HPLC of the dihydrodiols formed in the metabolism of 3-methylcholanthrene by rat-liver microsomal preparations showed the presence of trans-4,5-dihydro-4,5-dihydoxy-3-methylcholanthrene, trans-7,8-dihydro-7,8-dihydroxy-3-methylcholanthrene, trans-9,10-dihydro-9,10-dihydroxy-3-methylcholanthrene and trans-11,12-dihydro-11,12-dihydroxy-3-methylcholanthrene, identified by comparison of their UV and chromatographic characteristics with those of authentic standards. Tentative identification of cis- and trans-1,2-dihydroxy-3-methylcholanthrene, cis-2a,3-dihydroxy-3-methylcholanthrene and cis-11,12-dihydro-11,12-dihydroxy-3-methylcholanthrene as metabolites were made from their mobilities using HPLC. A quantitative comparison of the dihydrodiols formed from 3H-labelled 3-methylcholanthrene by microsomal preparations from the livers of normal and 3-methylcholanthrene-treated rats was carried out. trans-9,10-Dihydro-9,10-dihydroxy-3-methylcholanthrene and cis- and trans-1,2-dihydroxy-3-methylcholanthrene were formed when 3-methylcholanthrene was incubated with mouse skin in organ culture.

Animals↗
PubMed1978

Induction of sister-chromatid exchanges in Chinese hamster ovary cells treated in vitro with non-K-region dihydrodiols of 7-methylbenz[a]anthracene and benzo[a]pyrene.

Studies were carried out on the incidence of sister-chromatid exchanges induced in Chinese hamster ovary cells by in vitro treatment with the polycyclic aromatic hydrocarbons 7-methylbenz[a]anthracene and benzo[a]pyrene and with related K-region and non-K-region dihydrodiols. Appreciable increased in the incidence of sister-chromatid exchanges were apparent in cells treated with non-K-region dihydrodiols: the most active compounds were 3,4-dihydro-3,4-dihydroxy-7-methylbenz[a]anthracene and 7,8-dihydro-7,8-dihydroxybenzo[a]pyrene and the effects were dose-dependent. The parent hydrocarbons and the related K-region dihydrodiols induced some sister-chromatid exchanges but they were considerably less active than these two non-K-region diols. The results suggest that this system may usefully be applied to studies aimed at determining which dihydrodiols are important in the metabolic activation of the carcinogenic polycyclic hydrocarbons. These and other results also infer that Chinese hamster ovary cells possess some intrinsic ability to metabolize such compounds in the absence of exogenous activation systems.

Animals↗
PubMed1977

The metabolic activation of 7-methylbenz(a)anthracene: the induction of malignant transformation and mutation in mammalian cells by non-K-region dihydrodiols.

Four different dihydrodiols derived from 7-methylbenz(a)anthracene have been tested, together with the parent hydrocarbon, for their ability to induce the in vitro malignant transformation of mouse M2 fibroblasts and mutations in V79 Chinese hamster cells. In the transformation tests withe the non-K-region dihydrodiols, the 3,4-diol was the most active dihydrodiol tested and the 8,9-diol was also more active than 7-methylbenz(a)anthracene itself; the 1,2-diol showed only slight activity. The K-region dihydrodiol, the 5,6-diol, which cannot be directly metabolized to a vicinal diol-epoxide, was inactive. These differences in biological activity were similar to those apparent in the results from the mutagenicity tests. The data support the general hypothesis that non-I-region dihydrodiols, which can be metabolized to vicinal diol-epoxides, are important in the metabolic activation of the carcinogenic polycyclic hydrocarbons and, when taken together with other results, indicate that 3,4-dihydro-3,4-dihydroxy-7-methylbenz(a)anthracene is most probably involved in the metabolic activation of 7-methylbenz(a)anthracene presumably following conversion into the related diol-epoxide, 3,4-dihydro-3,4-dihydroxy-7-methylbenz(a)anthracene 1,2,-oxide.

Animals↗
PubMed1977

The metabolic activation of 7-methylbenz(a)anthracene in mouse skin.

The metabolism of 7-methylbenz(a)anthracene by rat-liver preparations and by mouse skin has been studied using a combination of thin-layer and high pressure liquid chromatography and all five possible trans-dihydrodiols have been detected as metabolites but in different proportions. The roles of these dihydrodiols and of the related vicinal diol-epoxides in the metabolic activation of 7-methylbenz(a)anthracene in mouse skin has been studied using Sephadex LH-20 column chromatography. The results show that the hydrocarbon-nucleic acid products formed in mouse skin in vivo most probably arise from 3,4-dihydro-3,4-dihydroxy-7-methylbenz(a)anthracene 1,2-oxide which, on the basis of this and other evidence, appears to be the reactive intermediate involved in the metabolic activation of 7-methylbenz(a)anthracene in this tissue.

Animals↗
PubMed1974

Nursing in Ireland.

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Education, Nursing, Diploma Programs↗
PubMed1974

Nurse education.

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Education, Nursing, Diploma Programs↗