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Biomedical subjects

Peter Bradley

Publications and source records attributed to Peter Bradley.

12 recordsLinked to original sources
PubMed2005

Identification of the moving junction complex of Toxoplasma gondii: a collaboration between distinct secretory organelles.

Apicomplexan parasites, including Toxoplasma gondii and Plasmodium sp., are obligate intracellular protozoa. They enter into a host cell by attaching to and then creating an invagination in the host cell plasma membrane. Contact between parasite and host plasma membranes occurs in the form of a ring-shaped moving junction that begins at the anterior end of the parasite and then migrates posteriorly. The resulting invagination of host plasma membrane creates a parasitophorous vacuole that completely envelops the now intracellular parasite. At the start of this process, apical membrane antigen 1 (AMA1) is released onto the parasite surface from specialized secretory organelles called micronemes. The T. gondii version of this protein, TgAMA1, has been shown to be essential for invasion but its exact role has not previously been determined. We identify here a trio of proteins that associate with TgAMA1, at least one of which associates with TgAMA1 at the moving junction. Surprisingly, these new proteins derive not from micronemes, but from the anterior secretory organelles known as rhoptries and specifically, for at least two, from the neck portion of these club-shaped structures. Homologues for these AMA1-associated proteins are found throughout the Apicomplexa strongly suggesting that this moving junction apparatus is a conserved feature of this important class of parasites. Differences between the contributing proteins in different species may, in part, be the result of selective pressure from the different niches occupied by these parasites.

Animals↗
PubMed2005

Comparison of directed and self-directed learning in evidence-based medicine: a randomised controlled trial.

OBJECTIVES: To compare 2 educational programmes for teaching evidence-based medicine (EBM). DESIGN: Prospective randomised controlled trial accompanied by a qualitative evaluation. SETTING: University of Oslo, Norway, 2002-03. PARTICIPANTS: A total of 175 students entered the study. All tenth semester medical students from 3 semesters were eligible for inclusion if they completed baseline assessment and consent forms and either attended teaching on the first day of the semester or gave reasons for their absence on the first day in advance. Interventions One intervention was based on computer-assisted, self-directed learning (self-directed intervention), whilst the other was organised as workshops based on social learning theory (directed intervention). Both educational interventions consisted of 5 half-day sessions. MAIN OUTCOME MEASURES: The primary outcomes were knowledge about EBM and skills in critical appraisal. A secondary outcome measured attitudes to EBM. Outcomes were compared on an intention-to-treat basis using a stratified Wilcoxon rank-sum test. RESULTS: There were no differences in outcomes for the 2 study groups in terms of EBM knowledge (mean deviation 0.0 [95% confidence interval - 1.0, 1.0], P = 0.8), critical appraisal skills (MD 0.1 [95% CI - 0.9, 1.1], P = 0.5), or attitudes to EBM (MD - 0.3 [95% CI - 1.4, 0.8], P = 0.5). Follow-up rates were 96%, 97% and 63%, respectively. CONCLUSIONS: This trial and its accompanying qualitative evaluation suggest that self-directed, computer-assisted learning may be an alternative format for teaching EBM. However, further research is needed to confirm this and investigate alternative educational models.

Adult↗
PubMed2005

Medical students' and tutors' experiences of directed and self-directed learning programs in evidence-based medicine: a qualitative evaluation accompanying a randomized controlled trial.

This qualitative study aims to interpret the results of a randomized controlled trial comparing two educational programs (directed learning and self-directed learning) in evidence-based medicine (EBM) for medical students at the University of Oslo from 2002 to 2003. There is currently very little comparative educational research in this field. In the trial, no statistically significant differences between the study groups were shown for any outcomes considered (EBM knowledge, skills, and attitudes). Further analysis suggests that main reason for the negative trial results was that the majority of students learned equally effectively, whichever program they received, although implementation of the educational programs was not complete because of varying attendance. This study illustrates a stepwise evaluation model that might be useful in evaluating other socially complex interventions.

Education, Medical, Undergraduate↗
PubMed2003

Randomised controlled trial of a theoretically grounded tailored intervention to diffuse evidence-based public health practice [ISRCTN23257060].

BACKGROUND: Previous studies have shown that Norwegian public health physicians do not systematically and explicitly use scientific evidence in their practice. They work in an environment that does not encourage the integration of this information in decision-making. In this study we investigate whether a theoretically grounded tailored intervention to diffuse evidence-based public health practice increases the physicians' use of research information. METHODS: 148 self-selected public health physicians were randomised to an intervention group (n = 73) and a control group (n = 75). The intervention group received a multifaceted intervention while the control group received a letter declaring that they had access to library services. Baseline assessments before the intervention and post-testing immediately at the end of a 1.5-year intervention period were conducted. The intervention was theoretically based and consisted of a workshop in evidence-based public health, a newsletter, access to a specially designed information service, to relevant databases, and to an electronic discussion list. The main outcome measure was behaviour as measured by the use of research in different documents. RESULTS: The intervention did not demonstrate any evidence of effects on the objective behaviour outcomes. We found, however, a statistical significant difference between the two groups for both knowledge scores: Mean difference of 0.4 (95% CI: 0.2-0.6) in the score for knowledge about EBM-resources and mean difference of 0.2 (95% CI: 0.0-0.3) in the score for conceptual knowledge of importance for critical appraisal. There were no statistical significant differences in attitude-, self-efficacy-, decision-to-adopt- or job-satisfaction scales. There were no significant differences in Cochrane library searching after controlling for baseline values and characteristics. CONCLUSION: Though demonstrating effect on knowledge the study failed to provide support for the hypothesis that a theory-based multifaceted intervention targeted at identified barriers will change professional behaviour.

Evidence-Based Medicine↗
PubMed2003

Many a slip between cup and lip. Process evaluation of a program to promote and support evidence-based public health practice.

The main aims of this study are to document whether an intervention for promoting evidence-based public health practice had been delivered as intended and to explore the reasons for its lack of impact. Process data from the implementation of the program and data from interviews with 40 public health physicians are analyzed. Although they expressed satisfaction with the service, the doctors experienced the program as rather irrelevant for their daily work. They did not perceive that they dealt with many issues relevant for the use of research information, and if they did, referring to research would not make any difference to the way others perceived their advice. There is a need to develop more overlying strategies for integrating evidence into decision making than addressing the individual level.

Algorithms↗
PubMed2002

Systematic reviews of specialist epilepsy services.

BACKGROUND: Concern has been expressed over UK epilepsy service standards but the most clinically effective model of care is unknown. OBJECTIVE: To systematically review the current evidence on specialist epilepsy clinics compared to general neurology clinics and specialist epilepsy nurses compared to usual care. METHODS: Medline, Psychlit, Embase, Healthplan, GEARS, BIDS ISI, UKCHHO, international HTA websites, InterTASC databases and The Cochrane Library were searched to September 1999. Any studies comparing specialist epilepsy clinics or nurses to generalist services or usual care, reporting physical health, costs or generic quality-of-life outcomes were included. Two people independently applied inclusion and exclusion criteria and extracted data independently. Randomized controlled trial (RCT) quality was assessed by Jadad score and other studies qualitatively by the likelihood of bias. RESULTS: Findings were one RCT and two other studies on epilepsy clinics and four RCTs and a controlled trial on epilepsy nurses. Data synthesis was inappropriate. Epilepsy clinics showed no evidence of reduced seizure frequency or severity, no quality-of-life information and were more expensive. Epilepsy nurse services showed no evidence of reduced seizure frequency or severity, no effect on quality-of-life but were less expensive. CONCLUSION: There is insufficient evidence to demonstrate the superiority of any particular care model for producing better health outcomes.

Ambulatory Care Facilities↗
PubMedDate not supplied

Routine, high-sensitivity, cold vapor atomic absorption spectrometric determination of total mercury in foods after low-temperature digestion.

A cold vapor atomic absorption spectrometric method was developed for the subnanogram-per-gram determination of total Hg in a wide variety of foods. Foods were weighed into 50 mL polypropylene centrifuge tubes and dried without charring at 55 degrees C in a circulating oven. Samples were then digested at 58 degrees C with HNO3, HCl, and H2O2. After matrix modification with solutions of 2% Mg(NO3)2, 0.01% Triton X-100, and Cu(II) at 10 microg/mL, samples were analyzed by using a CeTAC Technologies M-6000A dedicated Hg analyzer. Based on a 2 g sample weight, the detection limit of the method over 12 batches averaged 0.30 ng/g wet weight and ranged from 0.03 to 0.6 ng/g. Recoveries of Hg added to 17 different foods, analyzed in a routine manner, averaged 97%, and individual recoveries ranged from 77 to 107%. Accuracy was confirmed by analysis of 7 biological reference materials from the National Research Council of Canada and the National Institute of Standards and Technology. Stabilization of low concentrations of Hg in solutions containing no sample was required to prevent loss of Hg from blanks. In a comparison of NaCl, potassium dichromate, and Au(II), chloride was much more effective for stabilization than the other two, and HCl was used for subsequent stabilization.

Algorithms↗