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Biomedical subjects

G Hirst

Publications and source records attributed to G Hirst.

17 recordsLinked to original sources
PubMed2004

Gap junction communication dynamics and bystander effects from ultrasoft X-rays.

Gap junctions provide a route for small molecules to pass directly between cells. Toxic species may spread through junctions into 'bystander' cells, which may be exploited in chemotherapy and radiotherapy. However, this may be prevented by junction closure, and therefore an understanding of the dose-dependency of inhibition of communication and bystander effects is important. Low-energy ionising radiation (ultrasoft X-rays) provides a tool for the study of bystander effects because the area of exposure may be carefully controlled, and thus target cells may be clearly defined. Loss of gap junction-mediated intercellular communication between irradiated cells was dose-dependent, indicating that closure of junctions is proportional to dose. Closure was associated with hyperphosphorylation of connexin43. Inhibition of communication occurred in bystander cells but was not proportional to dose. Inhibition of communication at higher radiation doses may restrict the spread of inhibitory factors, thus protecting bystander cells. The reduction in communication that takes place in bystander cells was dependent on cells being in physical contact, and not on the release of signalling factors into the medium.

Animals↗
PubMed2004

Making a meal of MRSA-the role of biosurgery in hospital-acquired infection.

Fly larvae have been used by many different cultures for treating wounds throughout history. Recently, their therapeutic actions have been scientifically defined. This article reviews the history of biosurgery and the most recent research, which demonstrates the therapeutic action of larvae and particularly their anti-MRSA properties.

Animals↗
PubMed2000

The roles of vertex sharp waves and K-complexes in the generation of N300 in auditory and respiratory-related evoked potentials during early stage 2 NREM sleep.

STUDY OBJECTIVES: To determine the scalp topography of the N300 response to stimuli of different modalities and to investigate the relationship of the N300 component to K-complexes and vertex sharp waves seen in the un-averaged EEG. DESIGN: Two experiments were conducted one using auditory; the other using respiratory occlusion stimuli presented during stage 2 sleep. Trials were classified on the basis of whether they produced a K-complex, a vertex sharp wave, or some other response. Auditory stimuli were presented in the form of an oddball paradigm, and averaged separately depending on whether they were "frequent" or "rare". In both experiments, responses were averaged separately based on the appearance of K-complexes, vertex sharps waves, or some "other" response to the stimuli. SETTING: Data were collected in the Melbourne University Sleep Laboratory. PARTICIPANTS: Young healthy male adults, eight in experiment 1 and six in experiment 2. INTERVENTIONS: NA. MEASUREMENTS AND RESULTS: Data were collected from 29 scalp sites. In all cases, N300 amplitude was maximal in the vertex sharp wave averages, despite being clearly present in the averages of K-complexes and "other" responses. The vertex maximal scalp topography of the N300 did not differ across response conditions or as a function of stimulus modality. This is consistent with the N300 being produced by the same intracranial generators in all cases. There were no effects of stimulus or response type on N300 latency. CONCLUSIONS: N300 should be viewed as a multi-modal component with a different underlying generator mechanism than that of the K-complex.

Adult↗
PubMed1999

The N550 component of the evoked K-complex: a modality non-specific response?

A large amplitude late negative deflection peaking between 500 and 650 ms is observable in the averaged K-complex wave-form. This peak is thus often labelled the N550. 'N550' appears during stage 2 and is maintained into slow wave sleep but is not apparent during REM. Most studies have employed auditory stimuli to elicit the K-complex. Two experiments were run to examine the effects of stimulus modality on the topographical distribution of the N550. In the first experiment, the K-complexes were elicited in an auditory oddball procedure. In the second experiment, K-complexes were elicited by respiratory occlusions. Twenty-nine channel recordings were used to increase spatial resolution. N550 was substantially larger in the average of trials containing K-complexes than in trials in which a K-complex could not be identified. N550 varied inversely in amplitude with the probability of accordance of the stimulus. The topographic distribution of the N550 was consistent between experiments. It was bilaterally symmetrical and was maximal over fronto-central regions of the scalp. The results indicate that the N550 reflects the activity of a modality non-specific, sleep dependent generator that responds to both interoceptive and external stimulation.

Adult↗
PubMed1998

Postgraduate education: does it improve the knowledge base of practitioners with time?

PURPOSE: We evaluate the effect of the provision of postgraduate educational material on improving practitioner knowledge base during a 3-year period. MATERIALS AND METHODS: A total of 210 urologists were provided 67 monographs in a 2-year period. They were given a pretest before and posttest 1 year after receipt of all monographs. RESULTS: There was significant improvement in posttest scores for the group as a whole. Improvement correlated with years post-training and number of monographs read. Multivariate analysis revealed the number of monographs read was the only independent predictor of outcome. CONCLUSIONS: Although the improvement in test scores was significant and did correlate with the postgraduate educational material read, it was modest. This finding raises significant concerns about the usefulness of this format for graduate medical education.

Clinical Competence↗
PubMed1998

Local implementation of national guidelines on lower urinary tract symptoms: what do general practitioners in Sydney, Australia suggest will work?

OBJECTIVES: Systematic reviews demonstrate that local initiatives are vital to implement nationally developed clinical practice guidelines. Evidence-based guidelines on the management of lower urinary tract symptoms in men were launched by the National Health and Medical Research Council in Sydney in April 1997. A study was conducted through interviews to establish patterns of care in the catchment area before the guidelines were implemented and general practitioners were surveyed in order to ascertain the most useful strategies for local implementation. DESIGN: A four-page questionnaire asked respondents to rate nine items about guideline dissemination; six items relating to the marketing of the guidelines and 15 implementation strategics: conventional educational activities (six); innovative educational strategies (four); quality improvement approaches (two) and patient-based approaches (three). SETTING: Sydney, Australia. STUDY PARTICIPANTS: Eighty-three randomly selected general practitioners (50 males; 33 females). RESULTS: Eighty-three out of 108 surveys were returned (77%). Respondents placed high value upon endorsement by eminent individuals and organizations other than the organization developing the guidelines; this was likely to gain their initial attention. One hundred per cent of respondents would be encouraged to use the guidelines if they were promoted as improving quality of care. Implementation strategies preferred by respondents included small group continuing education with a urologist and a general practitioner as a facilitator, lectures and patient education materials. Internet access, interactive computer systems, academic detailing' and distance education modules were of least interest. CONCLUSIONS: Our method is feasible as a first step in planning local dissemination and implementation for national guidelines. While useful in identifying preferred strategies, its longer-term predictive validity for improving patient outcomes through better guideline implementation needs to be established.

Adult↗
PubMed1995

Report of a workshop to review urological training in Australasia.

A review of the current Australasian urological training programme was undertaken by members of the Urological Society of Australasia in a workshop format. The participants worked in small groups developing strategies to overcome problems which the whole group had identified previously. The strategies proposed by the groups were subsequently edited and definitive recommendations developed. This paper details the final recommendations of the workshop and the intended steps towards their implementation.

Accreditation↗
PubMed1982

An evaluation of evidence for innate sex differences in linguistic ability.

A female superiority in verbal ability is reported on many tests. It has been hypothesized that the female brain is more functionally symmetrical for language then the male, and that this is the cause of the alleged superiority. Recent research has suggested that factors other than sex are involved: handedness, age of maturity, and endocrine influences. It is not yet clear whether, despite its biological correlates, the female superiority is innate.

Adolescent↗
PubMed1975

An ultrastructural study of the urinary bladder in children correlated with histological, bacteriological, and clinical findings.

Bladder biopsies from six boys without a history of urinary tract infection were taken during hypospadias repair operations and examined by electron microscopy. The ultrastructure of the epithelium, which was presumed to represent the normal, is described in detail and compared with the reported findings in other mammalian species. The appearances are generally similar although in our material the luminal membrane of the superficial cells was thicker than that surrounding the other epithelial cells but not asymmetrical. We observed membrane-coating granules which have not been reported before in bladder epithelium. The appearances of the normal bladder are compared to those seen in 24 children with urinary infection. In the presence of acute infection in large heterogeneous secondary lysosomes which are present in the intermediate and superficial cells of the normal bladder are reduced in number and the amount of rough endoplasmic reticulum is increased.

Adolescent↗
PubMedDate not supplied

Identification of systems failures in successful paediatric cardiac surgery.

Patient safety will benefit from an approach to human error that examines systemic causes, rather than blames individuals. This study describes a direct observation methodology, based on a threat and error model, prospectively to identify types and sources of systems failures in paediatric cardiac surgery. Of substantive interest were the range, frequency and types of failures that could be identified and whether minor failures could accumulate to form more serious events, as has been the case in other industries. Check lists, notes and video recordings were employed to observe 24 successful operations. A total of 366 failures were recorded. Coordination and communication problems, equipment problems, a relaxed safety culture, patient-related problems and perfusion-related problems were most frequent, with a smaller number of skill, knowledge and decision-making failures. Longer and more risky operations were likely to generate a greater number of minor failures than shorter and lower risk operations, and in seven higher-risk cases frequently occurring minor failures accumulated to threaten the safety of the patient. Non-technical errors were more prevalent than technical errors and task threats were the most prevalent systemic source of error. Adverse events in surgery are likely to be associated with a number of recurring and prospectively identifiable errors. These may be co-incident and cumulative human errors predisposed by threats embedded in the system, rather than due to individual incompetence or negligence. Prospectively identifying and reducing these recurrent failures would lead to improved surgical standards and enhanced patient safety.

Adolescent↗