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Biomedical subjects

R Thompson

Publications and source records attributed to R Thompson.

At least 73 records · Page 4Linked to original sources
PubMed2000

General practitioners leaving rural practice in Western Victoria.

The West Vic Division of General Practice, working with the Department of General Practice, The University of Queensland conducted a qualitative study of GPs who had left western Victoria over the previous 10 years to examine issues relating to the decision to leave rural practice. This study was conducted as part of a project to explore the role of rural Divisions in assisting with general practitioner recruitment and retention. The study supported the conclusions of a similar study in North Queensland and proposed a model that regards rural retention as an interplay of influences both positive and negative with acute trigger factors that can precipitate the decision to leave. Conflict and dissatisfaction with aspects of rural GP hospital work appeared to be a relatively frequent trigger factor that is immediately amenable to intervention from Divisions of general practice and through improvement in negotiation and conflict resolution skills for rural general practitioners.

Conflict, Psychological↗
PubMed2000

Case management: a model for the recruitment of rural general practitioners.

Many strategies have been trialed to recruit GPs to rural areas and to retain them once there. The West Vic Division of General Practice, a rural division in central-western Victoria, has developed and piloted a case management model. Case management is the holistic provision of services to meet an agreed outcome. Usually these processes are used to support clients with chronic or complex care needs. In this instance, the Division recognised that the sometimes puzzling and perplexing world of medical and provider registration, rural communities and the politics of bringing a doctor into a community requires specific skills and support. A dedicated and experienced case manager provides a continuous range of services to support the process from identification through to ongoing support within the community. The project has met with considerable success over the past 18 months, with 17 doctors placed in temporary and permanent positions.

Case Management↗
PubMed2000

Genetic defects in hepatocanalicular transport.

Bile is made as the result of active transport of its constituents into the biliary space. Most of this transport occurs across the canalicular membrane, with a further contribution from cholangiocytes. Water moves passively into bile. The major substrates that are transported out of hepatocytes are bile acids, phospholipids, cholesterol, and bilirubin. With the exception of cholesterol, each of these major substrates is now recognized to have its own transport mechanism. In the case of bile acids and phospholipids, the transporters appear to be specific, though the bilirubin transporter is multispecific. Isolated autosomal recessive defects in all three of these transporters have now been identified and have helped to confirm the physiologic role of these proteins. In addition, a secondary defect in bile acid transport has been identified that appears to be due to an abnormality in plasma membrane aminophospholipid distribution.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2000

An anti-inflammatory property of aprotinin detected at the level of leukocyte extravasation.

BACKGROUND: Aprotinin is a serine protease inhibitor used extensively in cardiac operations to reduce postoperative bleeding. It has also been used in trials aimed at reducing the systemic inflammatory response to cardiopulmonary bypass. It remains unclear whether the anti-inflammatory action of aprotinin is related to its general ability to suppress leukocyte activation or whether aprotinin can exercise effects during the leukocyte-endothelial cell adhesion cascade. METHODS: We used intravital microscopy to study the 3 main stages of the adhesion cascade (leukocyte rolling, firm adhesion, and extravasation) within the mesenteric microcirculation of rats. This in vivo technique allows leukocyte recruitment to be viewed directly through the transparent mesentery of anesthetized animals. RESULTS: Aprotinin, given by continuous infusion at a clinically relevant dose, exerted no effect on the rolling or firm adhesion responses toward local chemoattractant N -formyl-methyl-leucyl-phenylalanine but significantly inhibited extravasation of leukocytes (73% at 40 minutes, P =.04) into surrounding tissues. In parallel in vitro experiments, aprotinin (used at 200, 800, and 1600 kIU/mL) dose dependently inhibited neutrophil transmigration through cultured endothelial cells in response to 3 different chemoattractants: N -formyl-methyl-leucyl-phenylalanine (P <.001 at 800 and 1600 kIU/mL), interleukin 8 (P <.05 at 200 kIU/mL and P <.001 at 800 and 1600 kIU/mL), and platelet-activating factor (P <.05 at 1600 kIU/mL). CONCLUSIONS: Our studies have therefore revealed a novel anti-inflammatory mechanism of aprotinin operating at the level of leukocyte extravasation. These findings may be relevant in the prevention of systemic inflammation after cardiopulmonary bypass through the use of protease inhibitors.

Analysis of Variance↗
PubMed2000

Do oral appliances enlarge the airway in patients with obstructive sleep apnoea? A prospective computerized tomographic study.

This study evaluated the effect of an anterior mandibular positioning appliance (AMPA) on minimum pharyngeal cross-sectional area (MPCSA) in 32 conscious supine obstructive sleep apnoea (OSA) subjects. The change in MPCSA was measured using low dose computerized tomography, with and without an AMPA in situ. The results showed that the mean presenting respiratory disturbance index (RDI) was 26.6 events/hour, with a body mass index of 28.6 kg/m2 and mean age of 51.5 years. There was a statistically significant increase in MPCSA of 28.34 mm2 on appliance insertion (SD = 59.06 mm2; range -145 to +190 mm2; P = 0.011). The mean mandibular displacement was 5.73 mm (SD = 2.51 mm) in protrusion and 8.27 mm (SD = 4.51 mm) inferiorly. A poor correlation was found between the size of the mandibular displacement and the change in MPCSA (protrusion r = 0.268; inferiorly r = 0.240, P > 0.05). In conclusion, the AMPA significantly increased MPCSA, suggesting that it may be an effective therapy for OSA. There was, however, a wide but unpredictable individual variation of response. As a small number of patients may worsen in their condition with temporary mandibular advancement (TMA), it is essential that all patients treated with TMA should be investigated by polysomnography both before and after treatment.

Adult↗
PubMed2000

Pediatric liver disease.

Pediatric hepatology is no different than any other pediatric specialty. The prime objective is either to cure disease or to minimize its impact on the child. The result will be that children with chronic liver disease will become adults with chronic liver disease, and the long-term follow-up of pediatric liver disease will pass out of the hands of pediatricians. For this to happen effectively, continuous reappraisal of outcome data will be required to optimize treatment at all stages. It will also become important for physicians in adult practice to follow the progress being made in the management of pediatric liver disease.

Journal Article↗
PubMed2000

Linear and nonlinear measures predict swimming in the leech

Stimulation of a trigger interneuron of an isolated nerve cord preparation of the medicinal leech, Hirudo medicinalis, sometimes leads to swimming; sometimes it does not. We investigate signals transmitted in the ventral cord of the leech after stimulation and seek quantitative measures that would make it possible to distinguish signals that predict swimming from those that do not. We find that a number of linear as well as nonlinear measures provide statistically significant distinctions between the two kinds of signals. The linear measures are the time dependence of (i) the standard deviation and (ii) the autocorrelation function at a small time delay. The nonlinear measures are (i) a measure of nonlinear predictability and (ii) the time dependence of a measure of the size of the embedded signal trajectory. Calculations using surrogate data suggest that the differences between the two classes of signals are dynamical as well as statistical.

Journal Article↗
PubMed2000

Functional analysis of aberrant behavior through measurement of separate response topographies.

Functional analysis results for multiple topographies of aberrant behavior were graphed in an aggregate fashion and then separately for 48 clients. The results indicated that multiple topographies of behavior may be maintained by different contingencies. These results indicate that graphing functional analysis data in an aggregate fashion and then separately may improve the accuracy of their interpretation.

Adolescent↗
PubMed2000

A link function approach to model heterogeneity of residual variances over time in lactation curve analyses.

Several studies with test-day models for the lactation curve show heterogeneity of residual variance over time. The most common approach is to divide the lactation length into subclasses, assuming homogeneity within these classes and heterogeneity between them. The main drawbacks of this approach are that it can lead to many parameters being estimated and that classes have to be arbitrarily defined, whereas the residual variance changes continuously over time. A methodology that overcomes these drawbacks is proposed here. A structural model on the residual variance is assumed in which the covariates are parametric functions of time. In this model, only a few parameters need to be estimated, and the residual variance is then a continuous function of time. The analysis of a sample data set illustrates this methodology.

Analysis of Variance↗
PubMed2000

Can dietary assessment in general practice target patients with unhealthy diets?

Diet is important in the aetiology and management of many conditions in primary care. Although valid dietary assessment is required for both clinical work and research, no dietary assessment instruments have been validated among patients seen in primary care. A range of simple self-completion dietary assessment questionnaires and established research instruments were compared with an accepted reference standard, a seven-day weighed record, in 111 subjects assessed in a practice nurse-run treatment room. Simple self-completion tools based on food groups and portion sizes perform as well (likelihood ratios for a positive test = 2 to 3) as much more time-consuming instruments. The error in using such instruments is comparable with the error of the standard itself. There is little justification for using time-consuming dietary assessment questionnaires, since simple tools are accurate enough to be clinically useful--to allow practice nurses to target patients for counselling and waste less time on inappropriate counselling--and also useful for research.

Confidence Intervals↗
PubMed2000

Laser hair removal.

We are in a state of evolution in long-term hair removal. Safe and effective technology is now available. Lasers will always become smaller, faster, and perhaps more effective. For those interested in offering this procedure, evidence indicates that we are beyond the experimental phase. The treating physician should carefully review current available technology and receive proper training specific to that system.

Humans↗
PubMed2000

Evaluation of the AIDS Prevention Street Nurse Program: one step at a time.

The AIDS Prevention Street Nurse Program uses specially prepared community health nurses to focus on HIV and STD prevention with marginalized, hard-to-reach and high-risk clients within a broader context of harm reduction and health promotion. Street nurses (n = 17), service providers (n = 30), representatives of other HIV/STD programs in the province of British Columbia, Canada (N = 5), and clients (n = 32) were interviewed during an evaluation for the purpose of describing the nurses' work, the challenges the nurses' face, the fit of the program with other services, and the impact of the nurses' work. This article describes the impact of the nurses' work on clients. Impact/outcome changes reflected a progression from knowledge to behavioural levels and to major indicators of health/illness. Impact on clients included: knowing more about HIV/AIDS, their own situation, and options; receiving essential supplies to reduce harm and promote health; changing behaviour to reduce disease transmission, improve resistance, and promote health; connecting with help; feeling better about themselves and others; feeling supported; influencing others; receiving earlier attention for problems; being healthier with or without HIV; making major changes in drug use; and likely decreasing morbidity and mortality. The Program was found to be clearly effective in making a positive impact on clients.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Reduced immunotoxicity and preservation of antibacterial activity in a releasable side-chain carbapenem antibiotic.

A carbapenem antibiotic, L-786,392, was designed so that the side chain that provides high-affinity binding to the penicillin-binding proteins responsible for bacterial resistance was also the structural basis for ameliorating immunopathology. Expulsion of the side chain upon opening of the beta-lactam ring retained antibacterial activity while safely expelling the immunodominant epitope. L-786,392 was well tolerated in animal safety studies and had significant in vitro and in vivo activities against methicillin- and vancomycin-resistant Staphylococci and vancomycin-resistant Enterococci.

Animals↗
PubMed1999

The Genome Sequence DataBase: towards an integrated functional genomics resource.

During 1998 the primary focus of the Genome Sequence DataBase (GSDB; http://www.ncgr.org/gsdb ) located at the National Center for Genome Resources (NCGR) has been to improve data quality, improve data collections, and provide new methods and tools to access and analyze data. Data quality has been improved by extensive curation of certain data fields necessary for maintaining data collections and for using certain tools. Data quality has also been increased by improvements to the suite of programs that import data from the International Nucleotide Sequence Database Collaboration (IC). The Sequence Tag Alignment and Consensus Knowledgebase (STACK), a database of human expressed gene sequences developed by the South African National Bioinformatics Institute (SANBI), became available within the last year, allowing public access to this valuable resource of expressed sequences. Data access was improved by the addition of the Sequence Viewer, a platform-independent graphical viewer for GSDB sequence data. This tool has also been integrated with other searching and data retrieval tools. A BLAST homology search service was also made available, allowing researchers to search all of the data, including the unique data, that are available from GSDB. These improvements are designed to make GSDB more accessible to users, extend the rich searching capability already present in GSDB, and to facilitate the transition to an integrated system containing many different types of biological data.

Animals↗
PubMed1999

A numerical approach to non-circular birdcage RF coil optimization: verification with a fourth-order coil.

It is demonstrated that birdcage resonators, satisfying conditions of quadrature operation and radiofrequency field homogeneity, can be realized in practice on formers of non-circular cross section described by an equation of the form (x/a)n + (y/b)n = 1 where a and b are constants and n > or = 2 is an integer. Using a ladder network analogous to that of a conventional circular birdcage, optimization algorithms were employed to determine the elemental current distribution on the non-circular cylindrical surfaces. A comparison of circular, elliptical, symmetric and asymmetric fourth-order (n = 4) section birdcage current distributions is presented. A short, asymmetric fourth-order cage was constructed and tested experimentally at 3 T and compared with a conventional circular-section head coil.

Algorithms↗
PubMed1999

Indomethacin inhibits expansion of experimental aortic aneurysms via inhibition of the cox2 isoform of cyclooxygenase.

PURPOSE: Cyclooxygenase, either the cox1 or cox2 isoform, controls synthesis of prostaglandin E2 (PGE2), which regulates expression of matrix metalloprotease-9 (MMP-9). PGE2 and MMP-9 are elevated in aortic aneurysms. The mechanisms and time course of the inhibition of aneurysm expansion with a nonspecific cyclooxygenase inhibitor, indomethacin, were determined in an animal model. METHODS: Rats underwent aortic perfusion with saline (n = 40) as controls or with elastase. Elastase-treated animals received no treatment (n = 82) or received indomethacin (n = 73). Aortic diameters were determined at the time of aortic perfusion and when the rats were killed. The aortas were harvested and used for whole organ culture, substrate gel zymography, or histologic analysis. RESULTS: The control group demonstrated little change in aortic diameter. All the elastase-only animals developed aneurysms (maximal aortic diameter, 5.27 +/- 2.37 mm on day 14). Indomethacin markedly decreased the rate of aortic expansion (maximum aortic diameter, 3.45 +/- 1.11 mm; P <.001 vs the elastase-only group). The enzyme-linked immunosorbent assay of aortic explant culture media showed that PGE2 synthesis paralleled aortic expansion, and indomethacin decreased PGE2 synthesis. Histologically, the aortic elastin architecture was destroyed in the elastase group, but was preserved with indomethacin treatment. In situ, hybridization for cox1 and cox2 showed that cox2, but not cox1, was expressed and was co-localized by immunohistochemistry to macrophages associated with the aortic wall. Decreased levels of MMP-9 activity with indomethacin were shown by means of substrate zymography. MMP-9 was also localized to macrophages. CONCLUSION: Indomethacin attenuates aneurysm growth, and its effects are mediated via inhibition of the cox2 isoform of cyclooxygenase, which decreases PGE2 and MMP-9 synthesis.

Animals↗