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Biomedical subjects

L J Davies

Publications and source records attributed to L J Davies.

11 recordsLinked to original sources
PubMed2001

Analysing gene function after duplication.

After gene duplication, mutations cause the gene copies to diverge. The classical model predicts that these mutations will generally lead to the loss of function of one gene copy; rarely, new functions will be created and both duplicate genes are conserved. In contrast, under the subfunctionalization model both duplicates are preserved due to the partition of different functions between the duplicates. A recent study provides support for the subfunctionalization model, identifying several expressed gene duplicates common to humans and mice that contain regions conserved in one duplicate but variable in the other (and vice versa). We discuss both the methodology used in this study and also how gene phylogeny may lead to additional evidence for the importance of subfunctionalization in the evolution of new genes.

Animals↗
PubMed1989

The use of a simulated patient to assess clinical practice in the management of a high risk asthmatic.

Actors were trained to simulate a young asthmatic woman in the high risk category. Sixty-four of the 195 general practitioners and family medicine registrars in Christchurch city agreed to take part in the study in which they would be consulted by a simulated patient remaining blind to identification of the patient, the time and the medical problem. The simulators were trained to record information from the consultation and rate doctor behaviour when presenting, as a new patient on transfer, for a repeat prescription of asthma medication. Forty-nine doctors had one consultation and of these 25 had a second. Consultation time averaged 15.6 minutes and waiting time 17.4 minutes. Practice nurses and physiotherapists were rarely utilised. There were no specialist referrals. Serum theophylline levels were estimated in 4%. The chest was examined in 39% of consultations, the peak flow in 59%, both in 30% and neither in 32%. Drug prophylaxis was encouraged in 62%, home peak flow meter monitoring was encouraged in 49%, smoking was discouraged in 41%, aerosol technique was checked in 1%, a crisis plan was provided in 57% and asthma education in 42%. Doctor behaviour and communication skills were rated highly except that clear instruction on follow up appointments was given in only 24%. The second consultation appeared to be a briefer rerun of the first, indicating episodic care rather than planned long term management. A number of issues were identified for further study and education.

Adult↗
PubMed1986

The use of simulated patients in the assessment of actual clinical performance in general practice.

This pilot study assessed a novel approach to the evaluation of clinical performance in the practice setting, using actors trained to simulate real patients. Thirteen general practitioner teachers, 10 family medicine training programme registrars, and 10 recent graduates of the FMTP were recruited. They agreed to be consulted by an unknown simulated patient. Two young patients with classical migraine were selected. Two young actors, a male and a female, were trained to simulate their symptomatology and history. A scoring system was devised to broadly assess a single general practice first consultation, and the simulators were trained to score. Eighty-five percent of respondents were willing to take part in a further study. Seventy-three percent had no suspicion at all that the patient was simulated. The average consultation time was 17 minutes (range 4-40). The average score was 67% (range 10-100%). The diagnosis was made in every case and a wide variety of treatments were prescribed. This appears to be a practical and acceptable method of assessing clinical performance.

Clinical Competence↗
PubMed1975

Metabolism of Tritiated Gibberellins in d-5 Dwarf Maize: I. In Excised Tissues and Intact Dwarf and Normal Plants.

Metabolism of [(3)H]gibberellin A(1) ([(3)H]GA(1)) was followed in intact seedlings and excised apices and leaf tissue of both dwarf and normal (tall) plants of d-5 maize (Zea mays L.). The three metabolites produced were tentatively identified as [(3)H]GA(s), [(3)H]GA(s)-glucoside ([(3)H]GA(s)-glu), and [(3)H]GA(1)-X, an unknown.In 3-hour, pulse-labeling experiments with tissues of incubated, expanding leaves, more than 70% of the [(3)H]GA(1) taken up was metabolized to the three products within 12 to 15 hours. [(3)H]GA(1) fed to the roots of 7-day-old seedlings was readily translocated to the leaves, and all three metabolites were found in both roots and leaves. [(3)H]GA(1)-X was the major metabolite in roots, whereas in leaves the major metabolite was [(3)H]GA(s)-glu. There were no consistent differences in [(3)H]GA(1) metabolism between dwarf and normal plants, indicating that dwarfism in d-5 maize is not associated with modified GA(1) metabolism.In excised, mature leaf tissue, [(3)H]GA(1) metabolism was slower than in excised, young leaf tissue. Mature leaf tissues produced [(3)H]GA(s)-glu as by far the major metabolite, with [(3)H]GA(s) and [(3)H]GA(1)-X as minor metabolites. In contrast, in young leaves the three metabolites appeared sequentially in significant proportions: [(3)H]GA(8) first, followed by [(3)H]GA(s)-glu and, finally, [(3)H]GA(1)-X.

Journal Article↗
PubMed1975

Metabolism of Tritiated Gibberellins in d-5 Dward Maize: II. [H]Gibberellin A(1), [H]Gibberellin A(3), and Related Compounds.

After 30 minutes of incubation of young leaf sections of d-5 maize (Zea mays L.) in [(3)H]gibberellin A(1) ([(3)H]GA(1)), the metabolite [(3)H]GA(8) was present in significant amounts, with a second metabolite, [(3)H]GA(8)-glucose ([(3)H]GA(8)-glu), appearing soon after. A third [(3)H]GA(1) metabolite, the polar uncharacterized conjugate [(3)H]GA(1)-X, took more than 1 hour to appear. The protein synthesis inhibitor cycloheximide inhibited the production of all [(3)H]GA(1) metabolites, indicating a possible protein synthesis requirement for [(3)H]GA(1) metabolism.By preincubating leaf sections in unlabeled GA(1) before exposure to [(3)H]GA(1) or by reducing the specific radioactivity of the [(3)H]GA(1) supplied, it was possible to reduce greatly the conversion of radioactive GA(1) to [(3)H]GA(8)-glu, without affecting conversion to [(3)H]GA(1)-X. Increasing the molar concentration of the [(3)H]GA(1) fed greatly increased the molar yield of [(3)H]GA(1)-X, whereas the molar yields of [(3)H]GA(8) and [(3)H]GA(8)-glu were much less affected.The principal metabolite of [(3)H]GA(3) was a very polar compound having chromatographic properties similar to those of the conjugate [(3)H]GA(1)-X produced from [(3)H]GA(1). The naturally occurring GAs [(3)H]GA(1), [(3)H]GA(3), and [(3)H]tetrahydroGA(3) were metabolized to a much greater extent than were the artifical derivatives [(3)H]ketoGA(1), [(3)H]GA(1)-methyl ester, and [(3)H]pseudoGA(1). Only [(3)H]GA(1) and [(3)H]GA(3), with their identical D ring structures, were converted to [(3)H]GA(1)-X type compounds; [(3)H]-ketoGA(1) and [(3)H]tetrahydroGA(3), with modified D rings, were not converted to this type of conjugate.

Journal Article↗