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D Batty

Publications and source records attributed to D Batty.

At least 19 recordsLinked to original sources
PubMed2000

Stable binding of human XPC complex to irradiated DNA confers strong discrimination for damaged sites.

Nucleotide excision repair (NER) of DNA damage requires an efficient means of discrimination between damaged and non-damaged DNA. Cells from humans with xeroderma pigmentosum group C do not perform NER in the bulk of the genome and are corrected by XPC protein, which forms a complex with hHR23B protein. This complex preferentially binds to some types of damaged DNA, but the extent of discrimination in comparison to other NER proteins has not been clear. Recombinant XPC, hHR23B, and XPC-hHR23B complex were purified. In a reconstituted repair system, hHR23B stimulated XPC activity tenfold. Electrophoretic mobility-shift competition measurements revealed a 400-fold preference for binding of XPC-hHR23B to UV damaged over non-damaged DNA. This damage preference is much greater than displayed by the XPA protein. The discrimination power is similar to that determined here in parallel for the XP-E factor UV-DDB, despite the considerably greater molar affinity of UV-DDB for DNA. Binding of XPC-hHR23B to UV damaged DNA was very fast. Damaged DNA-XPC-hHR23B complexes were stable, with half of the complexes remaining four hours after challenge with excess UV-damaged DNA at 30 degrees C. XPC-hHR23B had a higher level of affinity for (6-4) photoproducts than cyclobutane pyrimidine dimers, and some affinity for DNA treated with cisplatin and alkylating agents. XPC-hHR23B could bind to single-stranded M13 DNA, but only poorly to single-stranded homopolymers. The strong preference of XPC complex for structures in damaged duplex DNA indicates its importance as a primary damage recognition factor in non-transcribed DNA during human NER.

Animals↗
PubMed2000

Reliability of a physical activity questionnaire in middle-aged men.

Although some items from a questionnaire used to assess occupational and leisure activity in a cohort of male factory workers have reasonable validity, their reliability is unknown. In this study the reliability of this questionnaire was assessed in 54 middle-aged male factory employees by test-retest administration over a 4-6 week period. Kappa statistics for test-retest agreement for individual items on the questionnaire ranged between 0.24 and 0.66. Those items that demonstrated reasonable reliability and validity will subsequently be related to a range of disease endpoints in a prospective cohort study.

Cohort Studies↗
PubMed1999

Isolation, characterization, and biological activity of naphthoquinones from Calceolaria andina L.

Two compounds recognized as responsible for the insecticidal activity of extracts of Calceolaria andina L. (Scrophulariaceae) have been isolated and characterized as 2-(1, 1-dimethylprop-2-enyl)-3-hydroxy-1,4-naphthoquinone and the corresponding acetate, 2-acetoxy-3-(1,1-dimethylprop-2-enyl)-1, 4-naphthoquinone. Their activities against 29 pest species and 9 beneficial species of arthropod from a total of 11 orders have been determined. Activities against homopteran and acarine species are of the same order as those of established pesticides, and, significantly, no cross-resistance is observed for strains resistant to established classes of insecticide. Mammalian toxicities are low.

Animals↗
PubMed1997

Human phosphodiesterase 4A: characterization of full-length and truncated enzymes expressed in COS cells.

The type 4 phosphodiesterase (PDE) family comprises four enzymes (4A, 4B, 4C and 4D) that are characterized by their specificity for cAMP and selective inhibition by the anti-depressant drug rolipram (4-[3-(cyclopentoxyl)-4-methoxyphenyl]2-pyrrolidone). In common with other PDEs, they consist of a central conserved domain associated with catalytic activity in addition to two N-terminal upstream conserved regions (UCR1 and UCR2) that are unique to the type 4 enzymes. We have isolated a 2 kb cDNA encoding a full-length type 4A PDE{HSPDE4A4B[Bolger, Michaeli, Martins, St.John, Steiner, Rodgers, Riggs, Wigler and Ferguson (1993) Mol. Cell. Biol. 13, 6558-6571]} from a human frontal cortex cDNA library. Northern blot analysis showed that the major PDE4A mRNA of 4.5 kb was widely distributed in different human tissues. The recombinant PDE4A expressed in COS cells had a molecular mass of approx. 117 kDa as revealed by SDS/PAGE/Western blotting with a PDE4A-specific antibody and was specific for cAMP with a Km of 4.8 microM. The enzyme activity was potently inhibited by R-rolipram (IC50 204 nM) and showed a 2.7-fold stereoselectivity over the S enantiomer. Analysis of the kinetics of inhibition indicated that R-rolipram did not behave as a simple competitive inhibitor. Dixon replots suggested that there was more than one mode of interaction consistent with the detection in the enzyme of a high-affinity binding site for R-rolipram with a Kd of 2.3 nM. Truncation of the PDE4A enzyme by deletion mutagenesis showed that neither of the UCRs was required for catalytic activity and identified an approx. 71 kDa core enzyme with a K(m) for cAMP of 3.3 microM. In contrast with the full-length PDE4A, R-rolipram behaved as a simple competitive inhibitor of this form of the enzyme with decreased potency (IC50 1022 nM) and no stereoselectivity. In addition, no high-affinity rolipram-binding site was detected in the truncated enzyme, indicating that this interaction involves sequences upstream of the catalytic domain of the enzyme.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMedDate not supplied

Waiting-list buster.

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Health Care Reform↗
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Food for thought.

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Community Health Nursing↗
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The new Nye nurses.

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Awards and Prizes↗
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Pass the buck.

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Financing, Government↗