David J. Worthington

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In a study of 70 cases of trisomy 18 and 450 matched controls in the second trimester we have measured the maternal serum levels of the analytes alpha feto protein (AFP), free beta-human chorionic gonadotrophin (hCG) and pregnancy associated plasma protein-A (PAPP-A). We have found the median multiple of the median (MoM) of maternal serum free beta-hCG to(More)
The catalytic properties of glutathione reductase from human erythrocytes have been studied over a range of buffer conditions and substrate concentrations. This study provides optimal conditions for determining the basic kinetic parameters of the enzyme. The catalytic behaviour of glutathione reductase is consistent with spatially separated binding sites(More)
1 To examine the influence of age on beta-adrenergic receptor mechanisms, we have observed the cardiovascular, bronchial and metabolic effects of an intravenous infusion of the beta-adrenoceptor agonist terbutaline in healthy young and elderly female subjects (mean ages 20.9 and 72.1 years respectively). 2 There was a highly significant fall in systolic(More)
The extent to which beta-adrenoceptor blocking drugs counteract the biochemical responses to an infusion of terbutaline, a beta 2-adrenoceptor agonist, has been investigated. In this study the beta 1-selectivity of metoprolol was compared with the non-selective beta-adrenoceptor blocker propranolol. The hypokalaemia produced by an infusion of terbutaline(More)
We report a multicentre clinical field trial of a novel dual analyte enzyme immunoassay method for the simultaneous measurement of alpha-fetoprotein (AFP) and free beta-human choriogonadotropin (hCG) in the same microtitre well. The assay was shown to have good technical performance in the hands of all trial centres, with between assay coefficients of(More)
Weight correction of serum markers is widely used when screening for Down's syndrome and open neural tube defects (NTD) because marker concentrations decrease with increasing maternal weight. Log-linear regression is frequently used for determining weight correction factors, but recently reciprocal-linear regression has been suggested to have advantages. We(More)
Queueing theory continues to be one of the most researched areas of operational research, and has generated numerous review papers over the years. The phrase ‘queue modelling’ is used in the title to indicate a more practical emphasis. This paper uses work taken predominantly from the last 50 years of pages of the Operational Research Quarterly and the(More)
Terbutaline is a selective beta 2 agonist used predominantly in the treatment of asthma. Since beta-mediated responses increase heart rate, dilate peripheral arteries, modify carbohydrate metabolism and the uptake of electrolytes into cells, the administration of terbutaline might be expected to produce widespread effects. In this study the intravenous(More)