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Biomedical subjects

B A Laing

Publications and source records attributed to B A Laing.

10 recordsLinked to original sources
PubMed1996

Effects of magnetic stimulation over supplementary motor area on movement in Parkinson's disease.

Movement execution can be delayed by transcranial magnetic stimulation delivered over primary motor cortical areas, resulting in transient inhibition of cortico-motor output. Inhibition or disruption of higher-order motor planning and preparatory processes, such as are thought to occur in the supplementary motor area (SMA), would allow an examination of processes at other stages of the motor control system. In this study, six subjects with Parkinson's disease and six healthy control subjects performed a non-cued sequential finger movement task. At various times relative to movement, high-intensity single-pulse magnetic stimulation was delivered over the region of the SMA, with minimal current spread to primary motor areas. When magnetic stimulation was given at early stages during the movement for parkinsonian subjects, movement times were significantly increased, indicating disrupted movements. Supplementary motor area stimulation had no effect when delivered during later stages of the movement or immediately prior to movement onset, and had no apparent effect on control subjects at any time. It is therefore suggested that the SMA is important in motor planning and preparatory processes, since SMA stimulation has no effect on movements in their later stages when planning may be complete, but may disrupt movements in their early stages, when preparation for later stages may still be in progress. Further, possible instability of motor planning/preparation processes in Parkinson's disease is suggested, since these processes appeared more susceptible to disruption by magnetic stimulation in parkinsonian subjects than controls.

Aged↗
PubMed1995

Autosomal dominant distal myopathy: linkage to chromosome 14.

We have studied a family segregating a form of autosomal dominant distal myopathy (MIM 160500) and containing nine living affected individuals. The myopathy in this family is closest in clinical phenotype to that first described by Gowers in 1902. A search for linkage was conducted using microsatellite, VNTR, and RFLP markers. In total, 92 markers on all 22 autosomes were run. Positive linkage was obtained with 14 of 15 markers tested on chromosome 14, with little indication of linkage elsewhere in the genome. Maximum two-point LOD scores of 2.60 at recombination fraction .00 were obtained for the markers MYH7 and D14S64--the family structure precludes a two-point LOD score > or = 3. Recombinations with D14S72 and D14S49 indicate that this distal myopathy locus, MPD1, should lie between these markers. A multipoint analysis assuming 100% penetrance and using the markers D14S72, D14S50, MYH7, D14S64, D14S54, and D14S49 gave a LOD score of exactly 3 at MYH7. Analysis at a penetrance of 80% gave a LOD score of 2.8 at this marker. This probable localization of a gene for distal myopathy, MPD1, on chromosome 14 should allow other investigators studying distal myopathy families to test this region for linkage in other types of the disease, to confirm linkage or to demonstrate the likely genetic heterogeneity.

Adolescent↗
PubMed1993

Treatment of inflammatory myopathies.

Although there have been considerable advances in our understanding of the immunopathogenesis of the different forms of autoimmune inflammatory myopathy, the treatment of these conditions remains largely empirical, being based upon the use of immunosuppressive and immunomodulatory therapies which, for the most part, are non-selective in their actions. Corticosteroids are usually effective in adult and childhood cases of polymyositis and dermatomyositis, but are only rarely helpful in inclusion body myositis, which is usually also unresponsive to other forms of immunosuppressive therapy. Alternate-day corticosteroid therapy has a role in patients with mild disease and as a means of minimizing the side-effects of steroids. This may also be achieved by the early introduction of a second-line agent such as methotrexate or azathioprine, which will allow more rapid steroid withdrawal and may also improve the chances of inducing a remission in more severe cases. In patients who fail to respond adequately to oral corticosteroids, or who relapse after an initial response, intravenous immunoglobulin therapy or pulse therapy with intravenous methylprednisolone are promising approaches which appeal as safer alternatives to cytotoxic drugs. However these forms of treatment will require further evaluation in prospective clinical trials. The same applies to cyclosporin, which has a more selective action on T cells, and which has been reported to be effective in resistant cases of adult and juvenile polymyositis and dermatomyositis. In the longer term, the development of more specific forms of immunotherapy for these myopathies, aimed at blocking autoantigen presentation or its interaction with T cells, awaits the identification of the target antigens and T cells which initiate the autoimmune process.

Adult↗
PubMed1992

Childhood pedestrian injuries in the Perth metropolitan area.

OBJECTIVE: To examine the characteristics of childhood pedestrian injuries in the Perth metropolitan area from 1980 to 1989. DESIGN: Retrospective descriptive study. SETTING: Perth metropolitan area, Western Australia. PARTICIPANTS: Child pedestrians aged 0 to 14 years who were injured during the period 1 January 1980 to 31 December 1989. MAIN OUTCOME MEASURES: An extensive database which reported fatal and non-fatal motor vehicle collisions was used to obtain details on the child pedestrian, the vehicle involved in the collision, and the environmental factors related to these injuries. RESULTS: A total of 1282 child pedestrian injuries were reported in the 10 year period. Children aged between 5 and 9 years, and were overrepresented among those injured. This study also demonstrated a similar proportion of injuries involving the 10-14 year age group. Injuries frequently occurred mid block, on local urban roads, between the hours of 3 p.m. and 7 p.m., and a greater than expected proportion of drivers involved in these collisions were in the under-21 age category. To describe the pattern of childhood pedestrian injuries we calculated both age-specific injury rates, and injury rates based on the number of registered motor vehicles. The latter revealed a greater than 20-fold variation between local government areas. CONCLUSIONS: Further analytical research, incorporating a measure of the child pedestrian's exposure to roads and traffic is required to identify those features in the individual and the environment which have a significant influence on the likelihood of a collision. Such research is required to institute effective preventive measures.

Accidents↗
PubMed1992

Reduction of the concentration and total amount of keratan sulphate in synovial fluid from patients with osteoarthritis during treatment with piroxicam.

To study the effects of piroxicam on cartilage metabolism in vivo, a three phase (placebo/piroxicam 20 mg/day by mouth/placebo) double blind controlled trial was conducted in patients with osteoarthritis of the knee joint. Twenty one patients were recruited, 19 of whom (11 women, eight men, median age 70 years) completed the treatment schedule. The knee joint under study was aspirated to dryness at four week intervals. Treatment with piroxicam was accompanied by a decrease in the pain score, an improvement in the functional index, and an increased range of movement. Reductions in the concentration (mean (SEM) 120 (6) to 110 (8) micrograms/ml) and the total amount (1.22 (0.34) to 0.99 (0.37) mg) of keratan sulphate, but not the effusion volume (9.4 (2.5) to 8.3 (2.6) ml) were observed during treatment with piroxicam. These findings are consistent with decreased proteoglycan catabolism during treatment with piroxicam. Neither depressed synthesis nor enhanced clearance of degraded proteoglycan fragments can be excluded, however.

Adolescent↗
PubMed1991

Hydroxyapatite crystals are a frequent finding in osteoarthritic synovial fluid, but are not related to increased concentrations of keratan sulfate or interleukin 1 beta.

Synovial fluid (SF) was obtained from 40 patients with varying grades of osteoarthritis (OA) of the knee and examined by transmission electron microscopy to ascertain how frequently hydroxyapatite crystals (HA) were present and whether they were related to disease severity or putative markers or promoters of cartilage resorption. HA crystals were conspicuous and abundant in specimens from 21 of the 40 patients studied. Patients in whom HA was present had significantly larger effusions (13.0 +/- 8.9 vs 8.7 +/- 6.1 ml, p less than 0.05). They also tended to have radiologically more severe disease (radiological grade: 2.91 +/- 0.92 vs 2.39 +/- 0.85, p = 0.056). No difference in keratan sulfate (KS) concentrations was observed. Moreover, despite the presence in some specimens of numerous free histiocytes which were actively phagocytosing HA aggregates, the concentrations of interleukin 1 beta (IL-1 beta), a monocyte product with cartilage and bone resorbing activity, were below the limit of detection (20 pg/ml). Our results confirm that HA crystals are a common finding in patients with OA of the knee and show that HA is associated with larger effusions, but not increased SF concentrations of cartilage proteoglycan substituents (KS) or IL-1 beta.

Aged↗
PubMedDate not supplied

Factors contributing to the severity of childhood pedestrian injury in Perth, Western Australia.

Pedestrian-motor vehicle collisions that involved children aged 0 to 14 years in Perth, Western Australia were examined for the period 1980-1989 in order to identify factors which contribute to the severity of injury. Nearly half (49%) of the 1,282 children injured during this period required hospitalization, with a further 46% of the children requiring some form of medical treatment. Multivariate analysis indicated that children aged 0 to four years had a higher risk of sustaining a severe injury compared with children aged five to nine and ten to 14 years, with relative risks of 1.6 and 1.7 respectively. A greater proportion of more severe injuries occurred after 3 pm. Injuries tended to be more severe when the collision occurred on a highway or main road, and when the child was actually on the road at the point of impact. Further research on more comprehensive datasets, which consider the child's behavior at the time of injury as well as driver attributes, will provide greater insight into factors contributing to the severity of injury.

Accidents, Traffic↗