Biomedical subjects
Publications and source records attributed to R Gregory.
Ray Paton oversaw the creation of a long lineage of Individual-based Models (IbMs) and this paper discusses the five most successful. All of these concern the development of adaptation, covering both evolutionary time and organism lifetime (somatic time). Of the five models discussed here, the first is based on a plant-herbivore model, the other four are based on a substrate-bacteria model, with the option of antibiotics.
The concept of adaptive management has, for many ecologists, become a foundation of effective environmental management for initiatives characterized by high levels of ecological uncertainty. Yet problems associated with its application are legendary, and many of the initiatives promoted as examples of adaptive management appear to lack essential characteristics of the approach. In this paper we propose explicit criteria for helping managers and decision makers to determine the appropriateness of either passive or active adaptive-management strategies as a response to ecological uncertainty in environmental management. Four categories of criteria--dealing with spatial and temporal scale, dimensions of uncertainty, the evaluation of costs and benefits, and institutional and stakeholder support--are defined and applied using hypothetical yet realistic case-study scenarios that illustrate a range of environmental management problems. We conclude that many of the issues facing adaptive management may have less to do with the approach itself than with the indiscriminate choice of contexts within which it is now applied.
It is the practice in many centres to externalise deep brain electrodes in functional neurosurgery to confirm efficacy of therapy prior to full implantation of the pacemaker. It has been a concern that such practice might lead to an increased rate of infection. We report a retrospective study of the rates of infection in two major centres where all electrodes are externalised in one centre and directly implanted in the other. We have not found an increased rate of infection as a result of externalisation and feel, particularly in pain patients, that doing so can lead to significant cost savings by avoiding ineffective implantations.
Explore the source record for details and available documents.
Lesioning or chronic deep brain stimulation (DBS) of the nucleus ventralis intermedius results in abolition of tremor in the contralateral limbs in Parkinson's disease (PD) and also in essential tremor. Recently, chronic DBS of the subthalamic nucleus has also proved to be very effective in reducing contralateral limb tremor in PD. These targets have been less effective in controlling the complex limb tremor often seen in multiple sclerosis (MS). Consequently, other targets have been sought in cases of MS with tremor. We describe a patient with MS with disabling proximal and distal involuntary arm movements in whom we were able to obtain sustained control of contralateral arm tremor and achieve functional improvement of the affected arm by chronic DBS of the region of the zona incerta. We also highlight the important role played by local field potentials recorded from the brain, with simultaneous recording of corresponding EMGs, in target localisation.
Explore the source record for details and available documents.
To understand mechanistically how pRB represses transcription, we used a reconstituted transcription assay and compared pRB activity on naked versus chromatin templates. Surprisingly, when pRB was directly recruited to a naked template, no transcriptional repression was observed. However, we observed active repression when the same promoter was assembled into chromatin. Histone deacetylases do not appear to play a role in this observed repression. Further experiments showed repression could occur after preinitiation complex assembly, in contrast with pRB inhibition of E2F, suggesting discrete mechanisms by which pRB directly inhibits an activator such as E2F or actively represses proximally bound transcription factors.
Three patients with spasmodic torticollis (ST) obtained substantial benefit from bilateral globus pallidus internus (GPi) stimulation. Progressive improvement in ST occurred over several months but residual cervical dystonia remained. These results corroborate those obtained by Krauss et al. on three patients with ST.
AIMS/HYPOTHESIS: Estimates of incidence of Type I (insulin-dependent) diabetes mellitus in childhood populations vary around the world. This study aimed to estimate and compare the incidence of Type I diabetes in Leicestershire of children of South Asian and White or Other ethnic backgrounds. METHODS: All new cases of childhood-onset Type I diabetes diagnosed before 15 years of age in Leicestershire during the period 1989-98 were studied. Population data for Leicestershire from the 1991 census was used. Ethnicity was assigned to all children in the study according to their surnames. Incidence rates (95%-Confidence limits) for the South Asian and white or other ethnic group were estimated and compared. RESULTS: Over the 10-year period, 46 South Asian children and 263 children who were white or from another ethnic group fulfilled the criteria for inclusion in the study. Crude incidence rates per 100,000 person-years were 19.2 (12.0, 29.1) girls and 20.3 (13.0, 30.3) boys for South Asians and 17.7 (14.8, 21.1) girls and 17.7 (14.8, 20.9) boys for whites/others. Age and sex-specific rates were higher for South Asians over 5 years of age but differences were not statistically significant. CONCLUSION/INTERPRETATION: Type I diabetes incidence rates for South Asian children in Leicestershire were very similar to those for children who were in the white/other ethnic group, in contrast to very low rates reported from Asia. The convergence of rates for South Asians with other ethnic groups in Leicestershire suggests that environmental factors are more important than genetic predisposition in causing Type I diabetes in people of South Asian ethnic background.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Despite a shift in care delivery from inpatient to ambulatory care, performance measurement efforts for the different levels in ambulatory care settings such as individual physicians, individual clinics and physician organizations have not been widely instituted in the United States (U.S.). The Health Plan Employer Data and Information Set (HEDIS), the most widely used performance measurement set in the U.S., includes a number of measures that evaluate preventive and chronic care provided in ambulatory care facilities. While HEDIS has made important contributions to the tracking of ambulatory care quality, it is becoming increasingly apparent that the measurement set could be improved by providing quality of care information at the levels of greatest interest to consumers and purchasers of care, namely for individual physicians, clinics and physician organizations. This article focuses on the improvement opportunities for quality performance measurement systems in ambulatory care. Specific challenges to creating a sustainable performance measurement system at the level of physician organizations, such as defining the purpose of the system, the accountability logic, information and reporting needs and mechanisms for sustainable implementation, are discussed.
Public participation is now part of many decision making processes for managing environmental and technical risks. This article describes a test of a strategy to improve the quality of public input by combining themes from risk communication with the prescriptive decision process of value-focused thinking. It was hypothesized that participating in a structured, value-focused risk communication approach would lead people to make more thoughtful, better informed, and hence higher quality decisions by helping them to consider and discuss a wider array of decision-relevant issues and address key value trade-offs. It is also anticipated that utilizing a value-focused decision structure would make participants feel more comfortable with their decisions; more satisfied that their selected alternative reflected their key concerns; and, in the end, more satisfied with their decisions. To test these hypotheses, six groups comprised of 7 to 10 people participated in conventional "alternative-focused" risk communication workshops and eight groups participated in similar "value-focused" workshops. All workshops dealt with the management of risks to riverine salmon habitat from hydroelectric electricity generation. The results provided support for the hypotheses: the value-focused decision structure led to more thoughtful and better informed risk management decisions.
Ever since it was demonstrated about twenty years ago by two independent groups (Aziz et al. and Bergman et al.) that the cardinal clinical features of MPTP-induced Parkinson's disease (PD) in non-human primate models can be alleviated by lesions of the subthalamic nucleus (STN), this structure has been the focus of interest for functional neurosurgeons involved in the treatment of PD. Initially lesioning and later chronic high frequency stimulation of the STN has become the standard surgical target of akinetic PD. In this brief report we present our experience with 14 STN lesions (8 unilateral and 3 bilateral) confirmed by post-operative imaging. We found significant improvement in OFF rigidity and in ON tremor following unilateral lesions. The major complications were speech disturbance and L-Dopa resistant limb dystonia. Functional disability scores showed inconsistent reduction. There was insufficient data to comment on the significance of bilateral lesions; however, there was a similar pattern of improvement in tremor and speech disturbance. In addition, there was worsening of gait. We comment on the lower degree of improvement in motor scores in our series compared to the few others in recent literature and stress that even in these studies the UPDRS benefits did not translate directly into functional benefit for the patients.