Biomedical subjects
Publications and source records attributed to D Richards.
We live in an age of information, innovation and change. Clinical decision making based on good quality evidence should lead to more effective and efficient treatments. Each practitioner has a role in assessing this information. This paper outlines this role, together with the advantages and problems of introducing an evidence based approach to dentistry.
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OBJECTIVE: To determine the usefulness of an objective assessment of humeral soft tissue thickness in estimating birth weight in a population at risk for macrosomia. METHODS: Shortly before delivery, ultrasound examinations were performed on 95 women at risk of having macrosomic infants. In each case, the fetal humeral soft tissue thickness (the distance between the outer edge of the humerus to the skin surface on transverse views of the upper arm) was measured three times, and an average was taken. RESULTS: The humeral soft tissue thickness correlated significantly with birth weight (R2 = 0.40, P < .001) and ponderal index (R2 = 0.20, P = .02). The humeral soft tissue thickness was significantly higher in macrosomic infants (P < .001), in those with an abnormally high ponderal index (P = .02), and in infants whose deliveries were complicated by shoulder dystocia (P = .05). There was no apparent effect of maternal diabetes on the humeral soft tissue thickness. The humeral soft tissue thickness was more sensitive in predicting macrosomia than was the ultrasound-estimated fetal weight (88 versus 71%), but less specific (75 versus 91%). CONCLUSION: The humeral soft tissue thickness correlates with birth weight. However, its clinical use compared with other predictors remains to be defined.
The object of this study was to determine the relative importance of low birth weight, preterm birth, low maternal age, household size, exposure to maternal smoking, personal smoking at 16 yrs of age, early termination of breastfeeding and socioeconomic status in the aetiology of wheezing illness in the first 5 yrs of life, and on the persistence of this illness at 16 yrs of age. In 15,712 children born in Britain during one week of April 1970, the occurrence of wheezing by 5 yrs of age, and of wheezing in the past year at 16 yrs of age within this group were analysed in multivariate logistic regression against each potential risk factor. The independent determinants of wheezing by 5 yrs of age were male sex, maternal smoking during pregnancy (odds ratio (OR) for 15+ cigarettes.day-1 = 1.39; 95% confidence interval (95% CI) 1.22-1.58) and low birthweight (OR for birthweight < 2.5 kg = 1.26; 95% Cl 1.07-1.50). Of children who had wheezed by 5 yrs of age, 15% reported wheezing in the past 12 months at 16 yrs of age. The persistence of symptoms at 16 yrs of age was independently related to low maternal age (OR for 20 vs 40 yrs of age = 1.96; 95% CI 1.08-3.45) and to high social status (OR for most vs least advantaged = 1.95; 95% CI 1.13-3.38). We conclude that low birth weight and maternal smoking in pregnancy are independent risk factors for early childhood wheezing, but in 85% of children with early wheezing it resolves by 16 yrs of age.(ABSTRACT TRUNCATED AT 250 WORDS)
OBJECTIVES: The purpose of this study was to investigate the effects of prolonged arachidonic acid (AA) exposure on electrically induced fluctuations of cytosolic free Ca2+ concentration ([Ca2+]i) in cardiac myocytes and to identify intracellular biochemical events that may play a role in the actions of AA on [Ca2+]i dynamics. METHODS: Electrically induced [Ca2+]i transients were investigated in cultured single neonatal rat ventricular myocytes using spectrofluorometric analysis of fura-2-[Ca2+]i binding. KCl-induced depolarization, caffeine and ryanodine were used to assess the effects of AA on Ca2+ handling by the sarcolemma and the sarcoplasmic reticulum. Prostanoid formation was measured with an ELISA technique. alpha-Tocopherol was used to determine if free radical formation was a factor in the AA effects on [Ca2+]i. RESULTS: Exposure to 10-30 microM AA produced a concentration-dependent and reversible configuration change and eventually a cessation of [Ca2+]i transients. Continued exposure resulted in a Ca2+ overload (tonic [Ca2+]i greater than peak systolic [Ca2+]i). AA did not influence KCl-induced [Ca2+]i increase but did eliminate caffeine-induced [Ca2+]i transients. AA exposure stimulated the formation of 6-oxo-prostaglandin F1 alpha in a concentration-dependent manner, but thromboxane B2 formation was not influenced. alpha-Tocopherol pretreatment significantly delayed times till cessation of [Ca2+]i transients and Ca2+ overload, whereas ryanodine and cyclo-oxygenase inhibitors were without effect. CONCLUSIONS: The present data provide evidence that the initial action of AA on [Ca2+]i transients during excitation-contraction coupling involves an effect of AA on sarcolemmal Ca2+ influx and sarcoplasmic reticulum Ca2+ handling. AA-induced cessation of electrically induced [Ca2+]i transients and Ca2+ overload may involve the formation of free radicals.
AIM: To validate the Ottawa clinical decision rule for the use of radiography in acute ankle injuries. METHOD: A prospective, multicentre trial of 350 adult patients presenting with acute ankle injuries consisting of correlation of the features of the Ottawa clinical decision rule with the results of x-rays. RESULTS: There were 75 fractures in 350 patients, five of which would have been missed by the clinical decision rule. The sensitivity of the rule was 93% with a specificity of 11%. The positive predictive value was 22%, the false negative rate 14%. Fractures that would have been missed by the clinical decision rule included one unstable fracture of the ankle, one fracture of the talus, one calcaneal fracture and one fracture each of the cuboid and navicular. CONCLUSION: The Ottawa clinical decision rule for the use of radiography in acute ankle injuries is unacceptable for application in emergency departments in New Zealand due to a high false negative rate.
Before 1823, medical staffing of the antipodean penal colonies was determined by Whitehall rather than by demand for treatment. The parsimonious authorities were only too ready to make use of convicts' services.
Individual halogenated hydrocarbons (HC) have recently been demonstrated to depress Ca2+ dynamics in cardiomyocytes during excitation-contraction coupling. In the present study, eight widely used HC were systematically compared for their effects on Ca2+ dynamics in neonatal rat cardiomyocytes by means of spectrofluorometric analysis of fura-2-Ca(2+)-binding. Cells were exposed to dichloromethane (DCM), dichloroethane (DCE), 1,1,2-trichloroethane (112-TCE), trichloroethylene (TRI), halothane (HAL), 1,1,1-trichloroethane (111-TCE), perchloroethylene (PER), or pentachlorethane (PCE) in an environmentally controlled chamber. All HC tested decreased the height of electrically induced cytosolic free Ca2+ ([Ca2+]i) transients in a concentration-dependent and reversible manner (IC50 0.15-18.06 mM) without significant effects on diastolic [Ca2+]i. The increase in [Ca2+]i induced by depolarization with 90 mM KCl was inhibited to a lesser degree. Investigations with thapsigargin (100 nM) and ryanodine (1 microM)-inhibitors of Ca2+ release from the sarcoplasmic reticulum-provided evidence that the tonic Ca2+ response after KCl depolarization depends mainly on sarcolemmal Ca2+ influx. The potency of the eight HC to inhibit Ca2+ dynamics in cardiomyocytes correlated with their octanol/water partition coefficients. Results support the hypothesis that alteration of Ca2+ dynamics in cardiomyocytes is a common mechanism of cardiotoxic HC actions.
Free radical-induced oxidative stress has been linked to ischemia-reperfusion injury of the myocardium. The .OH radical is considered the most damaging radical and can be increased in cells by treatment in vitro with H2O2. The purpose of the present study was to determine if aliphatic halocarbons enhance H2O2-induced oxidative injury in isolated cardiac myocytes from neonatal rats. Oxidative damage was assessed by measuring release of thiobarbituric acid-reactive substances (TBARS) from lipid peroxidation, loss of lactate dehydrogenase (LDH) through damaged sarcolemmal membranes, and alterations in intracellular calcium ([Ca2+]i) transients in electrically stimulated (1 Hz, 10 ms, 60 V) myocytes. H2O2 increased TBARS release and LDH leakage in a concentration-dependent (20-200 microM) manner. Continuous suffusion with H2O2 first altered the configuration of [Ca2+]i transients, then eliminated them, and finally caused [Ca2+]i overload (basal [Ca2+]i exceeded peak systolic [Ca2+]i of control). The time to [Ca2+]i overload was inversely associated with concentration, and the shortest time to overload was obtained with 100 microM H2O2. A 1-h preincubation of myocytes with the iron chelator deferoxamine inhibited all effects of H2O2. 1,1,1-Trichloroethane, carbon tetrachloride, or halothane at 1 mM significantly and reversibly reduced [Ca2+]i transients but did not influence TBARS release or LDH leakage. Simultaneous exposure of myocytes to H2O2 and halocarbons did not affect the myocyte response to H2O2 exposure. Results indicate that the three halocarbons tested do not enhance H2O2-induced oxidative injury in isolated cardiac myocytes.
In this article, the effects of prescription drug coverage on use are analyzed for beneficiaries of a large retiree health benefit fund in a quasi-experiment comparing new and established enrollees. Newer enrollees show an 18-percentage point greater increase in prescription drug expenditures per capita than established enrollees during the 3-year period following enrollment. This differential is interpreted as the insurance effect of prescription coverage. The impact was greater among high-cost drugs than among low-cost drugs, and also greater among low users of prescription drugs than among high users. No clear patterns were discerned across therapeutic categories.
There is little doubt that the program fills a need in the health care system of this small community. We have met with some public resistance to the provision of services for drug 'addicts', sometimes from surprising quarters. There has also been significant resistance from some potential patients. Overall we believe that the successes achieved, although few, are worthwhile and may form a useful model for programs in other small rural communities.
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