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Biomedical subjects

R Bull

Publications and source records attributed to R Bull.

At least 19 recordsLinked to original sources
PubMed2004

Specificity of an immunochromatographic test for anthrax.

OBJECTIVE: To evaluate the specificity of an immunochromatographic test (ICT) for anthrax in cattle. DESIGN: A comparison of an ICT with blood smear and culture in uninfected cattle. PROCEDURE: Two hundred and forty blood samples were collected from dead cattle at two knackeries within Victoria and tested on-site with an ICT for the detection of protective antigen (PA) of Bacillus anthracis. Blood smears were prepared on-site and blood samples transported to the laboratory for aerobic and anaerobic culture. The results of the ICT were compared with blood smear and culture. Animals were regarded as not infected with B anthracis if the organism was not detected in a stained blood smear or on culture. Ten healthy yearling cattle were vaccinated with live spore anthrax vaccine and blood samples collected on days 0 to 7 and day 15 were tested in the ICT for the presence of PA. RESULTS: All blood samples from the 240 knackery cattle were ICT, smear and culture negative. All blood samples from the 10 vaccinated cattle were ICT negative. CONCLUSION: The ICT is a test with high specificity in cattle (98.5 to 100%; 95% CI) and recent vaccination of cattle does not give rise to positive reactions.

Animals↗
PubMed2003

UK laboratory intercomparison on internal dosimetry.

A laboratory intercomparison for internal dose assessment from a variety of intake scenarios is described. This is the first UK intercomparison using the revised ICRP Human Respiratory Tract and biokinetic models. Four United Kingdom laboratories participated and six cases were assessed. Overall, the agreement in internal dose assessments between laboratories was considered satisfactory with 79% of the assessed committed effective doses, e(50), for cases within a band of +/- 40% of the median value. The range (highest/lowest) in e(50) estimated by the laboratories was smallest (1.2) for a case involving inhalation of 137Cs. The range was greatest (6.0) for a case involving a wound with, and possible inhalation of, 238Pu, 239Pu and 241Am; the variation between laboratories in assessment of intakes could not be considered to be satisfactory in this case. Judgements on the most appropriate data to use in estimating intakes, choice of parameter values for use with the ICRP models and allowing for the effects of treatment with DTPA were important sources of variability between laboratories.

Body Burden↗
PubMed2001

Clinicians' contributions to healthcare management.

Primary tasks for clinical directors are to disseminate information to colleagues, provide feedback to senior professional managers, and to play key roles in strategic planning and resource allocation in health services. These tasks are seen to reduce barriers between clinicians and management. The application of clinical directorates across healthcare organisations is inconsistent and ambiguous. When set clear guidelines, clinical directors can impact on the decision-making process within senior management. As further applications of clinical directors in management occur, development of the role is required to realise the potential.

Conflict, Psychological↗
PubMed2001

Executive functioning as a predictor of children's mathematics ability: inhibition, switching, and working memory.

Children's mathematical skills were considered in relation to executive functions. Using multiple measures--including the Wisconsin Card Sorting Task (WCST), dual-task performance, Stroop task, and counting span-it was found that mathematical ability was significantly correlated with all measures of executive functioning, with the exception of dual-task performance. Furthermore, regression analyses revealed that each executive function measure predicted unique variance in mathematics ability. These results are discussed in terms of a central executive with diverse functions (Shallice & Burgess, 1996) and with recent evidence from Miyake, et al. (2000) showing the unity and diversity among executive functions. It is proposed that the particular difficulties for children of lower mathematical ability are lack of inhibition and poor working memory, which result in problems with switching and evaluation of new strategies for dealing with a particular task. The practical and theoretical implications of these results are discussed, along with suggestions for task changes and longitudinal studies that would clarify theoretical and developmental issues related to executive functioning.

Child↗
PubMed2001

People's insight into their own behaviour and speech content while lying.

The present experiment examined participants' insight into their own behaviour and speech content while lying. It was hypothesized that participants would believe that while lying they show more behaviour stereotypical of lying than they in fact do (Hypothesis 1), whereas they would believe that their own speech content while lying contains fewer stereotypical features than in fact is true (Hypothesis 2). A stereotypical response was defined as a response people generally believe liars usually show. A total of 86 nursing students were interviewed twice about a film they had just seen. During one interview they were asked to tell the truth whereas they had to lie in the other interview. All interviews were videotaped, transcribed and then scored by independent coders. The coders' analyses reveal participants' actual behaviour and speech content. Participants themselves were asked to indicate in a questionnaire how they believed they behaved and what they believed they said in both interviews. To test the hypotheses, comparisons were made between participants' actual responses and their beliefs about their own responses. The results support both hypotheses and implications of these outcomes for the detection of deception are discussed.

Adult↗
PubMed2000

The Judd illusion: evidence for two visual streams or two experimental conditions?

In the Judd illusion, observers inaccurately bisect the shaft located between two arrowheads pointing in the same direction. The magnitude of error is greater when verbal judgements are compared to action based responses (reaching out and grasping the centre of the bar). This difference has been attributed to the presence of two visual streams within cortical processing. In contrast, we provide evidence that the improved accuracy in the reaching condition may be due to occlusion of the illusory background during the transport phase of the movement. We suggest that caution is required when interpreting performance differences between two conditions that are not strictly equivalent.

Adult↗
PubMed2000

SH oxidation stimulates calcium release channels (ryanodine receptors) from excitable cells.

The effects of redox reagents on the activity of the intracellular calcium release channels (ryanodine receptors) of skeletal and cardiac muscle, or brain cortex neurons, was examined. In lipid bilayer experiments, oxidizing agents (2,2'-dithiodipyridine or thimerosal) modified the calcium dependence of all single channels studied. After controlled oxidation channels became active at sub microM calcium concentrations and were not inhibited by increasing the calcium concentration to 0.5 mM. Subsequent reduction reversed these effects. Channels purified from amphibian skeletal muscle exhibited the same behavior, indicating that the SH groups responsible for modifying the calcium dependence belong to the channel protein. Parallel experiments that measured calcium release through these channels in sarcoplasmic reticulum vesicles showed that following oxidation, the channels were no longer inhibited by sub mM concentrations of Mg2+. It is proposed that channel redox state controls the high affinity sites responsible for calcium activation as well as the low affinity sites involved in Mg2+ inhibition of channel activity. The possible physiological and pathological implications of these results are discussed.

Animals↗
PubMed1999

Dichloroacetate (DCA) dosimetry: interpreting DCA-induced liver cancer dose response and the potential for DCA to contribute to trichloroethylene-induced liver cancer.

Pharmacokinetic studies with dichloroacetate (DCA) provide insights into the likelihood that trichloroethylene-induced liver cancers arise from formation of DCA as a metabolite and the mode of action by which DCA induces liver cancer. A simple physiologically based pharmacokinetic model was developed to analyze DCA blood concentration data from mice unexposed to or pre-treated with DCA. The large first pass metabolism of DCA in the liver is significantly reduced by DCA pretreatment. Because DCA inhibits its own metabolism, large increases in area under the blood concentration curve occur at lower doses than would be predicted from single-dose pharmacokinetic studies with naive mice. The dose metrics associated with the incidence of liver tumors in contrast to the multiplicity of tumors per animal may be different, suggesting potentially different roles in the cancer process for DCA versus its metabolites. By linking a model for trichloroethylene (TCE) pharmacokinetics with the DCA model, maximum levels of DCA potentially produced from TCE were estimated to be at or below the analytical chemistry detection limits. In addition, the predicted levels of DCA would be too small to produce the observed liver cancers following corn oil gavage exposure of mice to TCE.

Animals↗
PubMed1999

This little piggy went to market: using a health education market as a learning strategy for preregistration Bachelor of Nursing students.

In the academic year 1997/98 at the University of Tasmania, students undertaking the research unit in their second year of the Bachelor of Nursing (BN) took part in producing a health education market for the staff and students on the Launceston campus of the University. The cafeteria and outside grassed areas were transformed into a network of information stalls, displays and activities. The students reported a constant flow of interested and enthusiastic people to their stalls. Integrating research findings, technical and interpersonal skills and creative ability, students were encouraged to synthesize many areas of theory in the nursing programme in order to present high quality, informative and engaging stalls. Formal evaluation of both group and individual work was integrated into the process in such a way as to provide prompt feedback and encouragement, ongoing quality control and to generate a final grade for each student.

Education, Nursing, Baccalaureate↗
PubMed1998

Viral ion channels: molecular modeling and simulation.

In a number of membrane-bound viruses, ion channels are formed by integral membrane proteins. These channel proteins include M2 from influenza A, NB from influenza B, and, possibly, Vpu from HIV-1. M2 is important in facilitating uncoating of the influenza A viral genome and is the target of amantadine, an anti-influenza drug. The biological roles of NB and Vpu are less certain. In all cases, the protein contains a single transmembrane alpha-helix close to its N-terminus. Channels can be formed by homo-oligomerization of these proteins, yielding bundles of transmembrane helices that span the membrane and surround a central ion-permeable pore. Molecular modeling may be used to integrate and interpret available experimental data concerning the structure of such transmembrane pores. This has proved successful for the M2 channel domain, where two independently derived models are in agreement with one another, and with solid-state nuclear magnetic resonance (NMR) data. Simulations based on channel models may yield insights into possible ion conduction and selectivity mechanisms.

Amino Acid Sequence↗
PubMed1998

Sulfhydryl oxidation modifies the calcium dependence of ryanodine-sensitive calcium channels of excitable cells.

The calcium dependence of ryanodine-sensitive single calcium channels was studied after fusing with planar lipid bilayers sarcoendoplasmic reticulum vesicles isolated from excitable tissues. Native channels from mammalian or amphibian skeletal muscle displayed three different calcium dependencies, cardiac (C), mammalian skeletal (MS), and low fractional open times (low Po), as reported for channels from brain cortex. Native channels from cardiac muscle presented only the MS and C dependencies. Channels with the MS or low Po behaviors showed bell-shaped calcium dependencies, but the latter had fractional open times of <0.1 at all [Ca2+]. Channels with C calcium dependence were activated by [Ca2+] < 10 microM and were not inhibited by increasing cis [Ca2+] up to 0.5 mM. After oxidation with 2,2'-dithiodipyridine or thimerosal, channels with low Po or MS dependencies increased their activity. These channels modified their calcium dependencies sequentially, from low Po to MS and C, or from MS to C. Reduction with glutathione of channels with C dependence (native or oxidized) decreased their fractional open times in 0.5 mM cis [Ca2+], from near unity to 0.1-0.3. These results show that all native channels displayed at least two calcium dependencies regardless of their origin, and that these changed after treatment with redox reagents.

Animals↗
PubMed1998

Cyclic ADP-ribose activates caffeine-sensitive calcium channels from sea urchin egg microsomes.

Adenosine 5'-cyclic diphosphoribose [cyclic ADP-ribose (cADPR)], a metabolite of NAD+ that promotes Ca2+ release from sea urchin egg homogenates and microsomal fractions, has been proposed to act as an endogenous agonist of Ca2+ release in sea urchin eggs. We describe experiments showing that a microsomal fraction isolated from Tetrapigus nyger sea urchin eggs displayed Ca(2+)-selective single channels with conductances of 155.0 +/- 8.0 pS in asymmetric Cs+ solutions and 47.5 +/- 1.1 pS in asymmetric Ca2+ solutions. These channels were sensitive to stimulation by Ca2+, ATP, and caffeine, but not inositol 1,4,5-trisphosphate, and were inhibited by ruthenium red. The channels were also activated by cADP-ribose in a Ca(2+)-dependent fashion. Calmodulin and Mg2+, but not heparin, modulated channel activity in the presence of cADP-ribose. We propose that these Ca2+ channels constitute the intracellular Ca(2+)-induced Ca2+ release pathway that is activated by cADP-ribose in sea urchin eggs.

Adenosine Diphosphate Ribose↗
PubMed1998

Common causes of leg ulceration.

Good treatment of any leg ulcer depends upon an accurate diagnosis of the underlying cause. Most leg ulcers occur secondary to venous or arterial disease but other rarer causes sometimes need to be considered. The treatment of the underlying condition is far more important than the choice of dressing.

Chronic Disease↗