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Biomedical subjects

A P Armstrong

Publications and source records attributed to A P Armstrong.

17 recordsLinked to original sources
PubMed2000

Patient satisfaction with Trilucent breast implants.

We report our findings in a retrospective study of patient satisfaction with soybean oil-filled mammary implants. Sixty-two women who had breast augmentation with Trilucent breast implants were sent a questionnaire to assess their satisfaction with implant placement; 19 of the 62 attended for clinical examination. Overall satisfaction with triglyceride implant placement was high: very pleased 45% (18/40), pleased 32.5% (13/40), content 12.5% (5/40). The majority of women felt that it had enhanced their body image and lifestyle (82.5%).

Body Image↗
PubMed1999

Mechanism-based inactivation of rat liver cytochrome P-450 2B1 by 2-methoxy-5-nitrobenzyl bromide.

Mechanism-based inactivators serve as probes of enzyme mechanism, function, and structure. Koshland's Reagent II (2-methoxy-5-nitrobenzyl bromide, KR-II) is a potential mechanism-based inactivator of enzymes that perform O-dealkylations. The major phenobarbital-inducible form of cytochrome P-450 in male rat liver microsomes, CYP2B1, is capable of catalyzing O-dealkylations. The interactions of KR-II with purified CYP2B1 in the reconstituted system containing P-450, NADPH:P-450 oxidoreductase, and sonicated dilaurylphosphatidyl choline were studied. The benzphetamine N-demethylase activity of CYP2B1 was inactivated by KR-II in a time- and NADPH-dependent manner, and the loss of activity followed pseudo-first-order kinetics. The inactivation also required KR-II, and the rate of activity loss was dependent on the concentration of KR-II in a saturable fashion. The inactivator concentration required for the half-maximal rate of inactivation (KI) was approximately 0.1 mM. The inactivation was not prevented by the addition of the nucleophiles dithiothreitol and glutathione, nor was it reversed by gel filtration. The present results demonstrate that KR-II is a mechanism-based inactivator of rat CYP2B1.

Animals↗
PubMed1997

Informed consent: are we doing enough?

We report our findings in a prospective, randomised study of patient recall of verbal versus written preoperative warnings. There were 132 patients in the verbal group and 137 in the written group, with a similar age and sex distribution in both groups. Four of the seven preoperative warnings were remembered significantly better by the group receiving the written warnings (P < 0.001-0.05). However, the mean number of warnings recalled was fewer than 3 in the verbal group, and fewer than 4 (P = 0.0057) in the written group (Mann-Whitney U-test). Patients given verbal warnings were less able to recall them than those receiving written warnings. The inference is that they entered into surgery less well informed.

Adult↗
PubMed1997

Intrauterine vascular deficiency of the upper limb.

We report six cases of intrauterine vascular deficiency of the upper limb, presenting over a 12-year period, with established areas of necrosis at the time of birth. Three of the six mothers were diabetic. An urgent examination of the neonate should be done to exclude occult systemic thomboses, as early anticoagulation or thrombolytic therapy may be indicated. The majority of cases were managed conservatively with dressings and splintage of the limb; exceptionally surgical intervention was required. Long-term sequelae included flexion contractures and shortening of the forearm bones.

Arm↗
PubMed1997

Olmsted's syndrome.

Explore the source record for details and available documents.

Follow-Up Studies↗
PubMed1996

Pathological findings in breast reduction surgery.

A retrospective analysis of pathological findings in 157 female patients undergoing breast reduction is presented. In 33 months 295 breasts were reduced. 25.6% of these patients had an abnormal pathology report, but no cases of premalignant disease or breast cancer were found. A postal questionnaire sent to consultant members of the British Association of Plastic Surgeons in 1994 found 89% routinely sent breast reduction tissue for pathological study. 42% had seen at least one case of breast cancer reported from this tissue. Recommendations for the use of pathology in breast reduction surgery are proposed.

Adolescent↗
PubMed1996

Apocrine hidrocystoma: report of a case.

A case of apocrine hidrocystoma, mimicking a naso-labial cyst of the maxilla is reported. The histopathological features and treatment of these rare lesions is discussed.

Apocrine Glands↗
PubMed1996

Mad proteins contain a dominant transcription repression domain.

Transcription repression by the basic region-helix-loop-helix-zipper (bHLHZip) protein Mad1 requires DNA binding as a ternary complex with Max and mSin3A or mSin3B, the mammalian orthologs of the Saccharomyces cerevisiae transcriptional corepressor SIN3. The interaction between Mad1 and mSin3 is mediated by three potential amphipathic alpha-helices: one in the N terminus of Mad (mSin interaction domain, or SID) and two within the second paired amphipathic helix domain (PAH2) of mSin3A. Mutations that alter the structure of the SID inhibit in vitro interaction between Mad and mSin3 and inactivate Mad's transcriptional repression activity. Here we show that a 35-residue region containing the SID represents a dominant repression domain whose activity can be transferred to a heterologous DNA binding region. A fusion protein comprising the Mad1 SID linked to a Ga14 DNA binding domain mediates repression of minimal as well as complex promoters dependent on Ga14 DNA binding sites. In addition, the SID represses the transcriptional activity of linked VP16 and c-Myc transactivation domains. When fused to a full-length c-Myc protein, the Mad1 SID specifically represses both c-Myc's transcriptional and transforming activities. Fusions between the GAL DNA binding domain and full-length mSin3 were also capable of repression. We show that the association between Mad1 and mSin3 is not only dependent on the helical SID but is also dependent on both putative helices of the mSin3 PAH2 region, suggesting that stable interaction requires all three helices. Our results indicate that the SID is necessary and sufficient for transcriptional repression mediated by the Mad protein family and that SID repression is dominant over several distinct transcriptional activators.

Amino Acid Sequence↗
PubMed1996

Nail gun injury: a barbed problem.

A case of nail gun injury is reported. Preoperative radiographs are essential to determine whether copper barbs project from the nail shaft before any attempt is made to remove the nail. Thorough exploration is required.

Accidents, Occupational↗
PubMed1994

Human T-cell leukemia virus type I Tax protein represses gene expression through the basic helix-loop-helix family of transcription factors.

The human T-cell leukemia virus type I (HTLV-I) oncoprotein Tax is a potent activator of viral and cellular gene transcription. Tax does not bind DNA directly but utilizes cellular transcription factors to mediate activation. In this report, we examine the role of the basic helix-loop-helix (bHLH) proteins in Tax deregulation of gene expression, as these proteins play a critical role in progression through the cell cycle and have been implicated in neoplastic disease. We show that the bHLH proteins do not mediate activation, but instead mediate repression of gene expression in the presence of Tax. We further show that a consensus bHLH binding site in the promoter of the beta-polymerase gene, which encodes an enzyme involved in DNA repair, mediates the previously reported repression of beta-polymerase gene expression by Tax. Together, these results suggest that Tax may induce malignant transformation, at least in part, through bHLH-mediated repression of key cellular regulatory genes.

Animals↗
PubMed1993

Pleiotropic effect of the human T-cell leukemia virus Tax protein on the DNA binding activity of eukaryotic transcription factors.

The Tax protein, encoded by the human T-cell leukemia virus type I, is a potent activator of viral and cellular gene transcription. Tax does not bind DNA directly but appears to trans-activate through an interaction with host-cell transcription factors that recognize sequences within the promoters of Tax-responsive genes. Cellular transcriptional activators implicated in mediating Tax trans-activation include members of the activating transcription factor/cAMP response element binding protein (ATF/CREB) family of proteins, serum response factor, Fos-Jun, and NF-kappa B. Recent evidence suggests that Tax may stimulate human T-cell leukemia virus type I transcription, at least in part, through enhanced binding of ATF/CREB proteins to their recognition elements within the Tax-responsive 21-bp repeats of the viral promoter. In this report, we demonstrate that Tax also enhances the site-specific DNA binding activity of serum response factor and Fos-Jun and modestly enhances the binding of the NF-kappa B subunits, p50 and p65. We also show that Tax increases the DNA binding activity of the eukaryotic transcription factors ATF-1, Sp1, and GAL4. These results are consistent with the finding that Tax is highly pleiotropic and suggest that Tax trans-activation may involve enhancement in the DNA binding activity of target transcriptional regulatory proteins. In addition, we show that the mechanism of Tax-enhanced DNA binding activity does not involve an alteration in the redox state of the target protein.

Base Sequence↗
PubMed1989

Oxidative N-demethylation of N,N-dimethylaniline by purified isozymes of cytochrome P-450.

The metabolism of N,N-dimethylaniline (DMA) by rabbit liver microsomes results in the formation of N-methylaniline (NMA) and formaldehyde. The N-oxide of DMA (DMA N-oxide) has been suggested as an intermediate in the cytochrome P-450-catalyzed demethylation reaction. The role of DMA N-oxide as an intermediate in demethylation has been investigated in a reconstituted system consisting of NADPH-cytochrome P-450 reductase, phospholipid, and several different purified isozymes of cytochrome P-450. The abilities of several cytochrome P-450 isozymes from rabbit liver (P-450 form 2 and P-450 form 4) and rat liver (P-450b and P-450c) to catalyze N-oxide formation and their abilities to catalyze demethylation of the N-oxide were determined and compared with their abilities to catalyze the demethylation of DMA. The metabolism of DMA by the purified isozymes of cytochrome P-450 in the reconstituted system did not result in the formation of measurable amounts of the N-oxide. The turnover numbers for the metabolism of DMA and DMA N-oxide to formaldehyde by the reconstituted system containing cytochrome P-450 form 2 were 25.6 and 3.4 nmol/min/nmol cytochrome P-450, respectively. The three other isozymes (P-450 form 4, P-450b, and P-450c) also exhibited significantly greater rates for the demethylation of DMA than for the N-oxide. If the N-oxide were an intermediate in the demethylation reaction, it should be metabolized at a rate greater than or at least equal to DMA. Therefore, these data, along with the inability to detect N-oxide formation during the cytochrome P-450-catalyzed demethylation of DMA, suggest that the N-oxide of DMA is not an intermediate in demethylation of DMA by these forms of cytochrome P-450 and that DMA N-oxidase activity is not associated with these isozymes.

Aniline Compounds↗
PubMed1989

Audiovisual demonstration for patient counselling in the use of pressurised aerosol bronchodilator inhalers.

The use of video as a method of instructing subjects on correct inhaler technique was compared with the written and personal instruction of 150 volunteer subjects with no previous experience of such a device. Video was found to be as effective as personal tuition by a pharmacist and significantly (P less than 0.05) superior to the manufacturer's package insert in teaching correct inhaler technique. The technique was assessed by a panel of five investigators in each case and was found to deteriorate over a 2-week period regardless of the instruction method. The video, which was prepared 'in-house', was then assessed in both the hospital out-patient and the general practice pharmacy settings. Asthmatic patients found the video useful at identifying mistakes they were making and felt that this approach to their education should be more widely available.

Adolescent↗