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Biomedical subjects

D A Abernethy

Publications and source records attributed to D A Abernethy.

12 recordsLinked to original sources
PubMed2006

Epidemiology of bovine brucellosis in Northern Ireland between 1990 and 2000.

Between 1990 and 2000, 317 herds of cattle in Northern Ireland were identified as being seropositive to Brucella abortus, and 68 per cent of them were attributed to transmission from neighbouring herds or to local spread. Of particular significance were three primary outbreaks in 1997, which resulted in significant secondary and tertiary spread. Three spatial clusters were identified, corresponding to two of the primary outbreaks, and the herd density and within-herd spread were highest in the largest cluster. Abortions in an infected herd and the disease-risk status of the disclosure test were positively associated with an increased within-herd prevalence.

Animals↗
PubMed2005

The Northern Ireland programme for the control and eradication of Mycobacterium bovis.

Bovine tuberculosis is endemic in Northern Ireland and a comprehensive eradication scheme has been in operation since 1959. The current programme involves annual testing, extensive computerized tracing, short-interval testing of herds contiguous to outbreaks and compulsory slaughter of positive cattle. Despite initial reductions in disease prevalence, eradication has proved elusive and potential explanatory factors include high cattle density and potential for between-herd contact, the impact of exotic diseases on resource priorities, and significant levels of bovine tuberculosis in a wildlife reservoir, the European badger (Meles meles). Both the role of the infected bovine and that of the badger in spreading disease have to be addressed to ensure progress towards eradication. Current measures are described and future options for enhancing the programme are outlined.

Animals↗
PubMed2005

On-line coal analysis using fast neutron-induced gamma-rays.

On-line measurement of bulk elemental composition is often best achieved with highly penetrative neutron-gamma techniques. CSIRO has developed and implemented one such technique, neutron inelastic-scattering and thermal-capture analysis (NITA). A distinctive feature of NITA is its use of fast neutron sources to generate inelastic scattering reactions, thus exciting gamma-rays from industrially important elements such as carbon and oxygen. A full-scale prototype for on-line coal quality measurement has been tested under simulated industrial conditions. The effect of sample compositional inhomogeneity and stream thickness will be discussed.

Journal Article↗
PubMed2005

Depression in multiple sclerosis: a review.

Several studies have reported high rates of depression in multiple sclerosis (MS) with a lifetime prevalence of approximately 50% and an annual prevalence of 20% not uncommon. Concern about the potential of new drug treatments to exacerbate or precipitate depression in MS has led to increased interest in the relation between MS and depression. This review on MS and depression identifies the following key issues: How common is depression in people with MS? Is depression in MS associated with lesions in specific regions of the central nervous system? Is there an increased risk of suicide in MS? Is there a higher than expected incidence of anxiety disorders in MS? Are fatigue and depressed mood related in MS? Is there a relation between depression and cognitive impairment in MS? Which psychosocial variables affect the development of depression in MS? Does treatment with interferon increase the risk of depression? How effective are treatments for MS patients with depression? Each of these issues is briefly reviewed with critical commentary, and some priorities for future research are suggested.

Adjuvants, Immunologic↗
PubMed2001

An on-belt elemental analyser for the cement industry.

On-line control of raw mill feed composition is a key factor in the improved control of cement plants. A new and improved on-conveyor belt elemental analyser for cement raw mill feed based on neutron inelastic scatter and capture techniques has been developed and tested successfully in Adelaide Brighton's Birkenhead cement plant on highly segregated material with a depth range of 100 to 180 mm. Dynamic tests in the plant have shown analyser RMS total errors of 0.49, 0.52, 0.38 and 0.23 wt% (on a loss free basis) for CaO, SiO2, Al2O3 and Fe2O3 respectively, when 10-minute counting periods are used.

Aluminum Oxide↗
PubMed1998

Neural architecture in transected rabbit sciatic nerve after prolonged nonreinnervation.

Observations have been made on the rabbit sciatic nerve distal to a transection, with survival periods of up to 26 mo and prevention of reinnervation. It was confirmed that the nerve becomes compartmented by fibroblast processes and that a zone of fine collagen fibrils develops around the Schwann cell columns that constitute the Büngner bands. The Schwann cells become progressively more atrophic but after 6 mo of denervation still expressed low affinity p75 nerve growth factor receptor (NGFR), the latest stage at which this was examined. NGFR was also expressed by the processes of the fibroblasts producing the endoneurial compartmentation. By 26 mo after transection the site of previous nerve fibres was indicated by sharply demarcated domains of approximately circular outline in transverse section consisting of densely packed longitudinally oriented collagen fibrils. Some of these domains still possessed centrally situated Schwann cells or residual basal lamina but many were acellular. The central collagen fibrils in these domains were of smaller diameter than those situated peripherally but were of larger size than those that form around the Büngner bands during wallerian degeneration. The peripherally located fibrils in the domains were of the same calibre as for normal endoneurial collagen. The collagen domains were encircled by fibroblast processes or at times enclosed in a perineurial cell ensheathment. Long-standing axonal loss therefore leads to a striking reorganisation of the internal architecture of peripheral nerve trunks. The findings may be relevant for the interpretation of the appearances in chronic peripheral neuropathies in man.

Animals↗
PubMed1994

Mutual attraction between emigrant cells from transected denervated nerve.

It is known that regenerating axons emerging from the proximal stump of a transected nerve are attracted towards the distal stump. It is not certain whether this neurotropic effect is on the axons themselves or whether it is on supporting cells such as Schwann cells that the axons then follow. In order to investigate this question in rats, segments of the sciatic nerve were either isolated or removed and reinserted as grafts, and then sutured into the opposing ends of double-Y silicone tubes. In these tubes, a central conduit was formed by connecting the centrally facing limb of each Y tube. The nerve segments were sutured into one of the limbs at either end. The third limbs of the Y tubes formed side arms, one of which was left open; a plug of mobilised fatty connective tissue was sutured into the other. A gap of 6 mm was left between the cut ends and the fat pads (or openings from the side arms). After 2-3 wk a significantly greater outgrowth (P < 0.001) was found to link the nerve segments than to invade the side arms. The major cell component in the outgrowth was Schwann cells, supported by fibroblasts and capillaries and surrounded by a lamellated layer of flattened fibroblasts. The growth into the side arms had a looser cellular architecture and contained considerably fewer Schwann cells. The results strongly suggest the existence of mutual attraction between emigrant Schwann cells, or possibly endoneurial fibroblasts, from the 2 cut ends of transected nerves. This conclusion has implications for the guidance of axons across gaps in nerves. It does not exclude an additional neurotropic effect from the distal stump on axons.

Animals↗
PubMed1992

Neurotropic influence of the distal stump of transected peripheral nerve on axonal regeneration: absence of topographic specificity in adult nerve.

Observations have been made on the growth of regenerating axons from transected rat sciatic nerve through Y-shaped silicone tubes. When the distal stump of the nerve was sutured into 1 distal limb of the tube and a fat pad into the other, a clear preference for the axons to regenerate towards the distal stump was found. In other experiments regenerating axons from the peroneal or tibial divisions of the sciatic nerve were given the choice of growing towards either the peroneal or tibial nerves, each being inserted into 1 of the 2 distal limbs of the Y-tube. No significant preference of the proximal stump to regenerate towards its appropriate distal stump was detected. A neurotropic influence of the distal stump on the nerve has therefore been confirmed, but topographic specificity of regeneration at the level of the nerve trunk has not been established.

Animals↗
PubMed1986

Cisplatin neuropathy with Lhermitte's sign.

Following chemotherapy with cis-diamminedichloroplatinum II (cisplatin) three patients developed Lhermitte's sign and peripheral neuropathy. The toxic side effects did not become apparent until after treatment had ceased. Because of increasing use of cisplatin to achieve lasting remission in patients with malignant disease proprioceptive and myelopathic side effects may become increasingly common.

Adult↗