Biomedical subjects
Publications and source records attributed to R Shepherd.
Defining the aetiology of facial pain can be difficult. While acknowledging the principle of 'common things are common', it is prudent to consider all possible causes. We describe a patient with posterior scleritis that presented as facial pain and was cured by oral prednisolone.
Time-resolved K-shell x-ray spectra are recorded from sub-100 nm aluminum foils irradiated by 150-fs laser pulses at relativistic intensities of Ilambda(2)=2 x 10(18) W microm(2)/cm(2). The thermal penetration depth is greater than the foil thickness in these targets so that uniform heating takes place at constant density before hydrodynamic motion occurs. The high-contrast, high-intensity laser pulse, broad spectral band, and short time resolution utilized in this experiment permit a simplified interpretation of the dynamical evolution of the radiating matter. The observed spectrum displays two distinct phases. At early time, < or =500 fs after detecting target emission, a broad quasicontinuous spectral feature with strong satellite emission from multiply excited levels is seen. At a later time, the He-like resonance line emission is dominant. The time-integrated data is in accord with previous studies with time resolution greater than 1 ps. The early time satellite emission is shown to be a signature of an initial large area, high density, low-temperature plasma created in the foil by fast electrons accelerated by the intense radiation field in the laser spot. We conclude that, because of this early time phenomenon and contrary to previous predictions, a short, high-intensity laser pulse incident on a thin foil does not create a uniform hot and dense plasma. The heating mechanism has been studied as a function of foil thickness, laser pulse length, and intensity. In addition, the spectra are found to be in broad agreement with a hydrodynamic expansion code postprocessed by a collisional-radiative model based on superconfiguration average rates and on the unresolved transition array formalism.
K-shell x-ray spectroscopy of sub-100 nm Al foils irradiated by high contrast, spatially uniform, 150 fs, Ilambda (2)=2 x 10(18) W microm(2)/cm(2), laser pulses is obtained with 500 fs time resolution. Two distinct phases occur: At </=500 fs a broad feature comparable to the resonance transitions occurs due to satellites, and at >/=500 fs the resonance transitions dominate. Initial satellites arise from a large area, high density, low temperature (approximately 100 eV) plasma created by fast electrons. Thus, contrary to predictions, a short, high intensity laser incident on a thin foil does not create a uniform, hot dense plasma.
BACKGROUND: The aim of this study was to compare the dental health of children with gastro-esophageal reflux disease (GERD) with a healthy control group. METHODS: Dental examinations were conducted for 52 children (31 boys and 21 girls) with a definitive history of GERD. For every subject enrolled in the study, a healthy control sibling without the condition was recruited. Medical histories were obtained from medical records, and dental and dietary histories were obtained from parents. The teeth were examined for erosion, dental caries, and enamel hypoplasia, and sampled for Streptococcus mutans. RESULTS: The prevalence of erosion by teeth was found to be statistically significant between GERD patients (14 per cent) and controls (10 per cent) (p<0.05). GERD patients had erosion in more permanent teeth compared to controls (4 per cent vs 0.8 per cent, p<0.05), and more severe erosion (p<0.05). Caries experience was also higher in GERD patients compared to controls (p<0.05). Although there were more subjects with Streptococcus mutans in the GERD group compared to the control group (42 per cent vs 25 per cent), the difference was not statistically significant. CONCLUSIONS: Children with GERD have more erosion and dental caries compared to healthy controls and should be targeted for increased preventive and restorative care.
Explore the source record for details and available documents.
The ion-distribution dynamics of an expanding aluminum plasma produced by a nanosecond laser pulse at moderate intensity (10(13) W cm(-2)) is studied by point-projection x-ray absorption spectroscopy with unprecedented, picosecond, time resolution. We show that the ionic populations measured as a function of distance to the target and at different probing times differ markedly from those predicted by widely accepted collisional radiative models coupled to hydrodynamic simulations. We discuss the effects of radiation, conduction, and expansion cooling on the spatiotemporal ionic distribution evolution.
UNLABELLED: Anorexia nervosa (AN) can lead to osteoporosis and fractures. OBJECTIVE: This study evaluated adolescent females with AN diagnosed within the previous 12 months to determine whether there is bone mass reduction and to investigate relationships between nutritional indices (weight, body mass index [BMI], lean mass, fat mass, and percentage fat) and total body (TB) and lumbar spine (LS) bone mineral densities (BMD) and content (BMC). METHOD: TB and LS BMD and BMC and body composition were measured in 24 adolescent females with AN. RESULTS: There was no significant reduction in TB or LS BMD. Regression analysis shows significant correlation (p < 0.001) between lean mass and TB BMD (r = +0.83), TB BMC (r = +0.92), LS BMD (r = +0.81), and LS BMC (r = +0.92). There was also a significant relationship between weight percentile and LS BMD z score (p < 0.005; r = +0.60). DISCUSSION: Adolescent females with early AN do not appear to have reduced bone mass. Lean mass is correlated to BMD and BMC.
A changing European food market demands insight into consumer attitudes and their influence on food choice and acceptability. This multidisciplinary area needs to bring together scientists from all regions of Europe and with very different scientific backgrounds. The primary objectives of this concerted action have been: to establish a base with state of the art methods for measurements of consumer attitudes; to review and test existing methods in practical applications in collaboration with European food industries; to perform comparative studies between laboratories on food products, where attitudes play different roles for consumer behaviour in the community countries, such as transgenic foods, irradiated foods, foods with different additives, declarations and process technologies, foods with different origin declarations, ecological foods and foods with strong health connotations (such as high-fat foods). The members of the action have published more than 130 publications related to aspects of how consumer attitudes can be measured and how food choice behaviour is related to acceptability, during the last four years. Studies have been conducted in relation to methodological aspects as well as particular studies related to specific food items and regions for food production. The paper will give a brief selection of relevant results from experiments reported through the action. During 2001 a textbook called "Food, People and Society, in a European Perspective", will be published. The book was initiated during the action and is later supported with additional authors. Altogether 29 chapters will cover the whole spectrum of topics from consumer food choice and acceptability to market perspectives and risk analysis.
OBJECTIVES: To determine the efficacy, safety, and tolerability of omeprazole in children and to determine the doses required to heal chronic, severe esophagitis. STUDY DESIGN: Open multicenter study in children aged 1 to 16 years with erosive reflux esophagitis. The healing dose of omeprazole used was that with which the duration of acid reflux was <6% of a 24-hour intraesophageal pH study. Follow-up endoscopy was performed after 3 months of treatment with the healing dose. RESULTS: At entry, two thirds of 57 patients who completed the study had esophagitis grade 3 or 4 (scale 0-4); some 50% had neurologic impairment or repaired esophageal atresia. Of the 57 patients, 54 healed; 3 did not heal and left the study, and 3 healed with a second course. Doses required for healing were 0.7 to 3.5 mg/kg/d: 0.7 mg/kg/d in 44% of patients and 1.4 mg/kg/d in another 28%. Healing dose correlated with grade of esophagitis but not with age or underlying disease. Reflux symptoms improved dramatically in almost all of the 57 patients, including the unhealed patients. CONCLUSIONS: Omeprazole is well tolerated, highly effective, and safe for treatment of erosive esophagitis and symptoms of gastroesophageal reflux in children, including children in whom antireflux surgery or other medical therapy has failed. On a per-kilogram basis, the doses of omeprazole required to heal erosive esophagitis are much greater than those required for adults.
OBJECTIVES: The aim of this study was to examine the pharmacokinetics of orally administered omeprazole in children. METHODS: Plasma concentrations of omeprazole were measured at steady state over a 6-h period after administration of the drug. Patients were a subset of those in a multicenter study to determine the dose, safety, efficacy, and tolerability of omeprazole in the treatment of erosive reflux esophagitis in children. Children were 1-16 yr of age, with erosive esophagitis and pathological acid reflux on 24 h-intraesophageal pH study. The "healing dose" of omeprazole was that at which subsequent intraesophageal pH study normalized. Children remained on this dose for 3 months, and during this period the pharmacokinetics were measured. RESULTS: A total of 57 children were enrolled in the overall healing phase of the study. Pharmacokinetic study was optional for subjects and was performed in 25 of the 57 enrolled. The doses of omeprazole required were substantially higher doses per kilogram of body weight than in adults. Values of the pharmacokinetic parameters of omeprazole were generally within the ranges previously reported in adults. However, the plasma levels, area under the plasma concentration versus time curve (AUC), plasma half-life (t(1/2)), and maximal plasma concentration (Cmax), were lower in the younger age group, when the AUC and Cmax were normalized to a dose of 1 mg/kg. Furthermore, within the group as a whole, these values showed a gradation from lowest in the children 1-6 yr of age to higher in the older age groups. CONCLUSIONS: The pharmacokinetics of omeprazole in children showed a trend toward higher metabolic capacity with decreasing age, being highest at 1-6 yr of age. This may explain the need for higher doses of omeprazole on a per kilogram basis, not only in children overall compared with adults but, in many cases, particularly in younger children.
Explore the source record for details and available documents.
The effects of reach distance and type of task on the functional relationship between the trunk, upper limb segments and the lower limbs during self-paced reaching in sitting were examined. Two-dimensional kinematic, kinetic and electromyography (EMG) data were collected as six healthy subjects reached forward under three distance (60, 100, 140% arm's length) and two task (reaching to press a switch, reaching to grasp a glass) conditions. The results demonstrate that type of task affected primarily the temporal aspects of coordination, with the grasp task taking consistently longer than the press task. In contrast, reach distance affected both the spatio-temporal aspects of coordination between the trunk and arm segments and the active contribution of the lower limbs. As reach distance increased, the magnitude of trunk and upper-arm segmental motion increased, whereas forearm segmental motion decreased. However, at each reach distance the path of the hand was relatively straight and there was remarkable consistency in the relationship between trunk and arm segments both within and between subjects suggesting that despite the presence of redundant degrees of freedom, the individual uses a parsimonious coordinative pattern. The vertical ground reaction force (GRF) and EMG data demonstrated that the lower limbs actively contributed to support the body mass when the object was located at 140% arm's length.
Food choice is influenced by a large number of factors, including social and cultural factors. One method for trying to understand the impact of these factors is through the study of attitudes. Research is described which utilizes social psychological attitude models of attitude-behaviour relationships, in particular the Theory of Planned Behaviour. This approach has shown good prediction of behaviour, but there are a number of possible extensions to this basic model which might improve its utility. One such extension is the inclusion of measures of moral concern, which have been found to be important both for the choice of genetically-modified foods and also for foods to be eaten by others. It has been found to be difficult to effect dietary change, and there are a number of insights from social psychology which might address this difficulty. One is the phenomenon of optimistic bias, where individuals believe themselves to be at less risk from various hazards than the average person. This effect has been demonstrated for nutritional risks, and this might lead individuals to take less note of health education messages. Another concern is that individuals do not always have clear-cut attitudes, but rather can be ambivalent about food and about healthy eating. It is important, therefore, to have measures for this ambivalence, and an understanding of how it might impact on behaviour.
Pancreatic enzyme replacement therapy (PERT) is a major factor associated with achieving optimum growth and nutritional status in cystic fibrosis (CF) patients with pancreatic insufficiency and consequent malabsorption. Currently in Australian CF clinics policies for the usage of PERT vary considerably. This paper highlights the current issues related to fat absorption and use of PERT in CF. It also provides evidence to support the recommendation of a PERT dose based on a standard ratio of lipase units per gram of dietary fat consumed for individual patients. A consistent approach to PERT doses will facilitate identification of patients whose PERT intake increases their risk of fibrosing colonopathy and for whom gastroenterological review is warranted. Recent reports indicate that PERT intake can be reduced with a secondary improvement in growth and nutrition status as a consequence of increased dietetic input. These Australian guidelines for the judicious use of PERT in CF should lead not only to a refinement in nutritional management of patients with CF but should also facilitate an improvement in compliance with therapy due to sophistication in patient education materials. The Australian guidelines for the use of PERT in CF if correctly applied, will also provide patients and their families with a better understanding of the relationship between PERT and nutritional status.
This paper proposes that the application of the Transtheoretical Model's stages of change to dietary behaviours may be fundamentally problematic due to the difference in nature between dietary behaviours and the addictive behaviours upon which the model was originally based. It was considered that specific problems associated with stage categorization for dietary change would include: problems due to the potential mismatch between a person's perceived and actual dietary behaviour; and problems due to the use of specific time periods to distinguish between different stages. A total of 541 volunteers completed questionnaires that measured their stage of change with respect to one of three dietary behaviours (healthy eating, eating a low-fat diet, and eating five portions of fruit and vegetables per day). Results indicate that people who were actively making a change (actors) or maintaining a change (maintainers) had done so for a range of different periods of time, with no specific cut-off point being evident. Also, more realistic stage categorizations were evident for the most specific dietary behaviours where there was least likelihood of a mismatch between perceived and actual dietary behaviour. Problems associated with issues of operationalization of the model and the application of the stage model to dietary change are discussed.
Explore the source record for details and available documents.
Alagille syndrome (AS) (arteriohepatic dysplasia, Alagille-Watson syndrome) is a multi-system disorder with hepatic, skeletal, eye, cardiac and renal manifestations. It results from mutation of the JAG1 gene, located on chromosome 20, which encodes a ligand for Notch receptor(s). The interactions of Notch receptors and their ligands are crucial in controlling cell fate decisions in a variety of developmental processes. AS varies in its severity, even in the same family, from asymptomatic gene carriers through to lethality due to inoperable cardiac or end-stage liver disease. However, advances in medical and surgical therapy have improved the prognosis at the severe end of the spectrum. It is hoped that the enhanced understanding of the biology of AS resulting from the cloning of the JAG1 gene will enable us to develop additional strategies for more effective treatments.