Characterization of antithrombins produced by active site mutagenesis of human alpha 1-antitrypsin expressed in yeast

Both congenital and acquired antithrombin-III (AT-III) deficiencies are amenable to replacement therapy. We describe two antithrombins produced by recombinant DNA techniques from human alpha 1-antitrypsin (alpha 1AT) cDNA in yeast. Alteration of the alpha 1AT active site, replacing methionine 358 with arginine, results in a thrombin inhibition rate similar to that of heparin-activated AT-III. Alteration of two further residues, to give a five-residue sequence identical to AT-III, does not increase this rate further. Neither antithrombin is activated by heparin; both are unglycosylated and have shorter in vivo half-lives (t1/2) than human alpha 1AT. These antithrombins should be suitable for therapeutic replacement of AT-III in cases of congenital deficiency and in conditions associated with acquired AT-III deficiency, such as disseminated intravascular coagulation.     

A COMPARATIVE STUDY OF THE EFFICACY AND TOXICITY OF ETODOLAC AND NAPROXEN IN THE TREATMENT OF OSTEOARTHRITIS

SUMMARY In a two-period, double-blind, crossover study, patients with osteoarthritis of the knee and/or hip received etodolac 300 mg twice daily for 4 weeks and naproxen 500 mg twice daily for 4 weeks in random order. The assessment of efficacy showed that naproxen and etodolac were equally effective in the management of pain and stiffness in osteoarthritis. However, a significantly higher proportion of patients preferred naproxen to etodolac for the relief of pain intensity. The incidence of adverse events caused by either drug was the same.     

Assessment of examiner leniency and stringency ('hawk-dove effect') in the MRCP(UK) clinical examination (PACES) using multi-facet Rasch modelling

Background

A potential problem of clinical examinations is known as the hawk-dove problem, some examiners being more stringent and requiring a higher performance than other examiners who are more lenient. Although the problem has been known qualitatively for at least a century, we know of no previous statistical estimation of the size of the effect in a large-scale, high-stakes examination. Here we use FACETS to carry out a multi-facet Rasch modelling of the paired judgements made by examiners in the clinical examination (PACES) of MRCP(UK), where identical candidates were assessed in identical situations, allowing calculation of examiner stringency.

Methods

Data were analysed from the first nine diets of PACES, which were taken between June 2001 and March 2004 by 10,145 candidates. Each candidate was assessed by two examiners on each of seven separate tasks. with the candidates assessed by a total of 1,259 examiners, resulting in a total of 142,030 marks. Examiner demographics were described in terms of age, sex, ethnicity, and total number of candidates examined.

Results

FACETS suggested that about 87% of main effect variance was due to candidate differences, 1% due to station differences, and 12% due to differences between examiners in leniency-stringency. Multiple regression suggested that greater examiner stringency was associated with greater examiner experience and being from an ethnic minority. Male and female examiners showed no overall difference in stringency. Examination scores were adjusted for examiner stringency and it was shown that for the present pass mark, the outcome for 95.9% of candidates would be unchanged using adjusted marks, whereas 2.6% of candidates would have passed, even though they had failed on the basis of raw marks, and 1.5% of candidates would have failed, despite passing on the basis of raw marks.

Conclusion

Examiners do differ in their leniency or stringency, and the effect can be estimated using Rasch modelling. The reasons for differences are not clear, but there are some demographic correlates, and the effects appear to be reliable across time. Account can be taken of differences, either by adjusting marks or, perhaps more effectively and more justifiably, by pairing high and low stringency examiners, so that raw marks can be used in the determination of pass and fail.     

The educational background and qualifications of UK medical students from ethnic minorities

Background

UK medical students and doctors from ethnic minorities underperform in undergraduate and postgraduate examinations. Although it is assumed that white (W) and non-white (NW) students enter medical school with similar qualifications, neither the qualifications of NW students, nor their educational background have been looked at in detail. This study uses two large-scale databases to examine the educational attainment of W and NW students.

Methods

Attainment at GCSE and A level, and selection for medical school in relation to ethnicity, were analysed in two separate databases. The 10^th cohort of the Youth Cohort Study provided data on 13,698 students taking GCSEs in 1999 in England and Wales, and their subsequent progression to A level. UCAS provided data for 1,484,650 applicants applying for admission to UK universities and colleges in 2003, 2004 and 2005, of whom 52,557 applied to medical school, and 23,443 were accepted.

Results

NW students achieve lower grades at GCSE overall, although achievement at the highest grades was similar to that of W students. NW students have higher educational aspirations, being more likely to go on to take A levels, especially in science and particularly chemistry, despite relatively lower achievement at GCSE. As a result, NW students perform less well at A level than W students, and hence NW students applying to university also have lower A-level grades than W students, both generally, and for medical school applicants. NW medical school entrants have lower A level grades than W entrants, with an effect size of about -0.10.

Conclusion

The effect size for the difference between white and non-white medical school entrants is about B0.10, which would mean that for a typical medical school examination there might be about 5 NW failures for each 4 W failures. However, this effect can only explain a portion of the overall effect size found in undergraduate and postgraduate examinations of about -0.32.     

Analysis of prolactin receptor expression in the murine brain using a novel prolactin receptor reporter mouse

Prolactin influences a wide range of physiological functions via actions within the central nervous system, as well as in peripheral tissues. A significant limitation in studies investigating these functions is the difficulty in identifying prolactin receptor (Prlr) expression, particularly in the brain. We have developed a novel mouse line using homologous recombination within mouse embryonic stem cells to produce a mouse in which an internal ribosome entry site (IRES) followed by Cre recombinase cDNA is inserted immediately after exon 10 in the Prlr gene, thereby targeting the long isoform of the Prlr. By crossing this Prlr‐IRES‐Cre mouse with a ROSA26‐CAGS‐tauGFP (τGFP) reporter mouse line, and using immunohistochemistry to detect τGFP, we were able to generate a detailed map of the distribution of individual Prlr‐expressing neurones and fibres throughout the brain of adult mice without the need for amplification of the GFP signal. Because the τGFP is targeted to neurotubules, the labelling detected not only cell bodies, but also processes of prolactin‐sensitive neurones. In both males and females, Cre‐dependent τGFP expression was localised, with varying degrees of abundance, in a number of brain regions, including the lateral septal nucleus, bed nucleus of the stria terminalis, preoptic and hypothalamic nuclei, medial habenula, posterodorsal medial amygdala, and brainstem regions such as the periaqueductal grey and parabrachial nucleus. The labelling was highly specific, occurring only in cells where we could also detect PrlrmRNA by in situ hybridisation. Apart from two brain areas, the anteroventral periventricular nucleus and the medial preoptic nucleus, the number and distribution of τGFP‐immunopositive cells was similar in males and females, suggesting that prolactin may have many equivalent functions in both sexes. These mice provide a valuable tool for investigating the neural circuits underlying the actions of prolactin.     

Unhappiness and dissatisfaction in doctors cannot be predicted by selectors from medical school application forms: A prospective,longitudinal study

Background  

Personal statements and referees' reports are widely used on medical school application forms, particularly in the UK, to assess the suitability of candidates for a career in medicine. However there are few studies which assess the validity of such information for predicting unhappiness or dissatisfaction with a career in medicine. Here we combine data from a long-term prospective study of medical student selection and training, with an experimental approach in which a large number of assessors used a paired comparison technique to predict outcome.