Biomedical subjects
Publications and source records attributed to S Lovell.
The crystal structure of 3,4-methylenedioxymethamphetamine [systematic name: N-methyl-1-[3,4-(methylenedioxy) phenyl]-2-aminopropane] hydrochloride, C11H15NO2.HCl, also known as 'ecstasy' or MDMA, has been determined by X-ray diffraction.
There is a concern that chemicals in our environment are affecting human health by disrupting normal endocrine function. Much of the concern has focused on chemicals that can interact directly with steroid hormone receptors. We have used a yeast-based assay to assess chemical interactions with the estrogen, androgen, and progesterone receptors. The yeast transformants used in this study contained the human estrogen, androgen, or progesterone receptor along with the appropriate steroid responsive elements upstream of the beta-galactosidase reporter gene. Chemicals were added to yeast cultures in doses ranging from 10(-12) to 10(-4) M and following incubation, the yeasts were then lysed and assayed for beta-galactosidase activity. Diethylstilbesterol and 17-beta estradiol were most active in the estrogen receptor assay, followed by the phytoestrogen, coumestrol. p-Nonylphenol and bisphenol A were approximately 5000- and 15,000-fold less active, respectively, than estradiol. Methoxychlor, DDT and its metabolites, o,p'-DDD, and o,p'-DDE ranged in potency from 5 to 24 X 10(6) less potent than estradiol. Testosterone and dihydrotestosterone were most potent in the androgen receptor assay, followed by estradiol and progesterone. p,p'-DDE was approximately 10(6)-fold less potent than testosterone. None of the industrial chemicals tested interacted with the progesterone receptor. These data demonstrate the utility of using yeast-based receptor assays for detecting chemical interaction with steroid receptors and these assays should serve as a useful component of an in vitro-in vivo strategy to assess the effects of chemicals on endocrine function.
Polyclonal antibody directed against the subfragment-2 region of myosin was purified by affinity chromatography. Skinned muscle fibers that had been preincubated with antibody were able to sustain only 7% of the active isometric force generated by control fibers. The effect of antibody on force production could not be accounted for by inhibition of ATP turnover.
Postoperative infection is an important complication after insertion of a ventriculoperitoneal (VP) shunt in children with hydrocephalus. A randomized double-blind placebo-controlled study was performed to determine the efficacy of cephalothin in preventing postoperative shunt infection. Sixty-three children who presented for elective VP shunt insertion between January 1982 and December 1985 and who did not have a history of shunt infections were randomly assigned to receive four doses of prophylactic cephalothin, 25 mg/kg (32 patients), or of a multivitamin placebo (31 patients). Postoperative infection developed in 6% of the treatment group, compared with 10% of the placebo group, a difference that was not statistically significant, although a clinical significance may have been masked by the small sample size. A large multicentre trial is needed to determine the efficacy of antibiotic prophylaxis in reducing the incidence of postoperative VP shunt infections.
Children admitted with acute gastroenteritis were managed with clear fluids and then given either the standard graduated feeding regimen or an abrupt reintroduction of normal feeds. The rapid refeeding group lost less weight, went home sooner, and had no increase in complication rate. Rapid refeeding is a reasonable option in the management of acute gastroenteritis.
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One hundred and forty-five children, aged 11-12 years, attending a primary school in a working class suburb of Brisbane, had their weights and heights measured and answered questions about their food intakes and home backgrounds. Analyses of the data showed that children of working mothers were more likely to be overweight (greater than or equal to 110% W/H); while eating calorie dense snack foods and frequent use of the school tuckshop was associated with less underweight (less than 90% W/H), but no increase in overweight. The use of convenience foods in the home was associated with increased underweight and decreased overweight.
One hundred and sixty-three Australian Aboriginals, who were aged from four months to 60 years, were examined clinically and otologically. Audiometric tests were completed on 110 of these subjects. On the assumptions that the aural health of these people has remained stable for many years, the cross-sectional data which were obtained have been used to infer the natural history of ear disease. Seromucinous otitis media is manifest as a disease of early childhood, which recovers spontaneously in most cases and has no obvious sequelae. Perforated tympanic membranes likewise seem to heal spontaneously in the majority of cases. The evidence suggests that hearing loss is the main problem and treatment should be directed towards the level of hearing loss and its effects.
Published statistical material has been used to analyse the infant death rate in Queensland. The neonatal death rates, which tend to reflect the level of obstetric care, were approximately twice as high in the Peninsula Division as in Brisbane, and the late infant mortality rate was almost eight times as high in the Peninsula Division as in Brisbane. In the Peninsula there has been no fall in infant death rate over the 11 years studied. One small area had an infant mortality rate of 100 deaths per 1,000 live births. The areas with the highest infant death rates were those with a significant Aboriginal population. The data show that proximity to major health facilities does not ensure low infant death rates and in the Brisbane Metropolitan Division there were threefold differences in late infant death rates. It seems likely that infant death rates are influenced by the economic status and education of parents and by the priority they place on infant care. The study has shown that published statistical data can detect areas within Queensland with high infant death rates, and could therfore be used to direct resources to improve the well-being of infants in these areas.
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The construction of an adiabatic flow calorimeter using water as the working substance is described. It is shown that at high dose rates the heat defect due to chemical reactions in water is small (of the order of 0-3%) and that under high dose rate conditions flow calorimetry can be used as a method of measuring the energy of high intensity electron beams. Measurements made with a 15 MeV linear accelerator are reported and compared with magnetic measurements.
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