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Biomedical subjects

P D Thompson

Publications and source records attributed to P D Thompson.

At least 19 recordsLinked to original sources
PubMed2006

Paranodal pathology in Tangier disease with remitting-relapsing multifocal neuropathy.

Pathological studies of a sural nerve biopsy in a man with Tangier disease presenting as a remitting-relapsing multifocal neuropathy showed abnormalities in the paranodal regions, including lipid deposition (65%) and redundant myelin foldings, with various degrees of myelin splitting and vesiculation (43%) forming small tomacula and abnormal myelin terminal loops (4%). The internodal regions were normal in the majority of myelinated fibres. Abnormal lipid storage was also present in the Schwann cells of the majority of unmyelinated fibres (67%). The evidence suggests that the noncompacted myelin region of the paranode is a preferential site for lipid storage in the myelinated Schwann cell, and that the space-occupying effects of the cholesterol esters leads to paranodal malfunction and tomacula formation as the pathological basis for the multifocal relapsing-remitting clinical course.

Adolescent↗
PubMed2006

Reasons for admission to hospital for Parkinson's disease.

The management of Parkinson's disease (PD) tends to focus on the presenting motor syndrome; yet, in the long term, nonmotor complications of the illness and complications of treatment become increasingly troublesome. The aims of this study were to review the reasons for 761 hospital admissions for patients with a diagnosis of PD and to determine the cause of hospitalization. Only 15% were admitted for primary management of the motor syndrome. PD was the secondary diagnosis in 645 admissions. Of the latter, 39% were admitted because of falls leading to fracture, pneumonia, encephalopathy or dementia and hypotension with syncope. Cardiac and gastrointestinal diseases accounted for a further 22% of admissions. Complications of the later stages of PD and associated treatments are more likely to lead to hospital admission than management of the primary motor syndrome. Some of the emergency hospital admissions for PD may be potentially avoidable with better planning of management in the outpatient and community setting.

Accidental Falls↗
PubMed2006

Treatment of cervical dystonia with botulinum toxins.

Botulinum toxin (BoNT) treatment has been used extensively for the treatment of cervical dystonia. In most studies, there is significant improvement following treatment for head posture and pain. The common side effects following treatment include dysphagia, dry mouth, and neck weakness. There are five brands and two serotypes of BoNT available. The dosing of each serotype and brand differs. Perhaps more importantly, each brand and serotype may differ in immunogenic potential and occurrence of secondary unresponsiveness, an issue that is currently under active investigation. Although many aspects of the technique of injection have not been adequately studied, general guidelines are available.

Anti-Dyskinesia Agents↗
PubMed2005

Early paranodal myelin swellings (tomacula) in an avian riboflavin deficiency model of demyelinating neuropathy.

INTRODUCTION: Disruption of the complex architectural and molecular organization of the paranodal region of myelinated peripheral nerve fiber may initiate the evolving time dependent process of segmental demyelination. In support of this notion was the finding of focal paranodal myelin swellings (tomacula) due to redundant folding of myelin sheaths, early in the time course of an avian riboflavin deficiency model of demyelinating neuropathy. METHODS: Newborn broiler meat chickens were maintained either on a routine diet containing 5.0 mg/kg riboflavin (control group) or a riboflavin-deficient diet containing 1.8 mg/kg riboflavin. Riboflavin concentrations in the liver were measured at postnatal day 11. Peripheral nerves were morphologically examined at days 6, 11, 16 and 21 using light and electron microscopy and teased nerve fiber techniques. RESULTS: Riboflavin-deficient chickens showed signs of a neuropathy from days 8 and pathological examination of peripheral nerves revealed a demyelinating neuropathy with paranodal tomacula formation starting on day 11. Paranodal tomacula consisted of redundant myelin infoldings or outfoldings, increased in size and frequency after day 11. After day 16, the paranodal swellings showed prominent degenerative changes accompanied by an increased frequency of myelinated fibers showing demyelination. CONCLUSION: Tomacula due to redundant myelin folds are generally considered a remyelination phenomenon, yet in this avian riboflavin deficiency model of demyelination, the paranodal tomacula occurred early in the course of demyelination.

Animals↗
PubMed2005

Motor cortex excitability after thalamic infarction.

Transcranial magnetic stimulation was used to map hand muscle representations in the motor cortex of a patient in whom infarction of the sensory thalamus deprived the sensorimotor cortex of sensory input. The threshold for activation of the motor cortex on the affected side was higher and the cortical representational maps of individual muscles were less well defined than those on the normal side. It is concluded that electrophysiological changes in cortical organisation can be demonstrated following withdrawal of, or imbalance in sensory afferent activity to the cerebral cortex in humans.

Adult↗
PubMed2004

The effect of physical activity on endothelial function in man.

Endothelial dysfunction occurs early in the atherosclerosis in response to elevated atherosclerotic risk factors, and endothelial dysfunction itself may exacerbate the atherosclerotic process. Treatments that reduce atherosclerotic risk factors also generally improve endothelial function. The present review seeks to summarize the effect of exercise training on endothelial function in human subjects. Cross-sectional studies comparing healthy physically active and inactive subjects as well as longitudinal exercise training studies of healthy individuals show little effect of exercise training on endothelial function. In contrast, both cross-section and longitudinal studies document improved endothelial function with exercise training in subjects with abnormal baseline endothelial function, including the elderly and patients with heart failure or coronary artery disease. Improvements in endothelial function with physical activity may explain some of the benefits of exercise in subjects with, or at risk for, vascular disease.

Adult↗
PubMed2003

Does induction of plastic change in motor cortex improve leg function after stroke?

Combined peripheral nerve and brain stimulation ("dual stimulation") induces changes in the excitability of normal motor cortex. The authors sought to establish whether dual stimulation would also induce motor cortex plasticity and associated functional improvements in nine stroke patients with chronic stable hemiparesis. Following 4 weeks of daily dual stimulation, improvements were seen in some neurophysiological and functional measures. This technique may offer therapeutic opportunities in some stroke patients.

Adult↗
PubMed2003

SUMO-1 marks the nuclear inclusions in familial neuronal intranuclear inclusion disease.

Neuronal intranuclear inclusion disease (NIID) is a rare neurodegenerative disorder characterized by progressive ataxia and neuronal nuclear inclusions (NIs), similar to the inclusions found in expanded CAG repeat diseases. NIID may be familial or sporadic. The cause of familial NIID is poorly understood, as no CAG expansion has been detected. We examined three cases, from two unrelated families, who had autosomal dominant NIID but normal CAG repeats in genes involved in polyglutamine neurodegenerative diseases. We found that NIs in all three cases were intensely immunopositive for SUMO-1, a protein which covalently conjugates to other proteins and targets them to the nuclear regions (nuclear bodies) responsible for nuclear proteasomal degradation. Electron microscopy demonstrated that SUMO-1 was located on the 10-nm fibrils of NIs. In cultured PC12 cells, we found that inhibition of proteasome function by specific inhibitors resulted in the appearance of SUMO-1-immunopositive nuclear inclusions. Our study suggests that recruitment of SUMO-1 modified proteins into insoluble nuclear inclusions and proteasomal dysfunction may be involved in the pathogenesis of NIs in familial NIID cases.

Adult↗
PubMed2003

Predictors of prolonged dysphagia following acute stroke.

Dysphagia following acute stroke frequently necessitates prolonged enteral feeding. There is evidence that early enteral feeding via percutaneous endoscopic gastrostomy (PEG) is both beneficial and safe. The aim of this study was to identify predictors of prolonged dysphagia. The subjects were 149 consecutive patients admitted with acute stroke. Clinical findings and imaging results were prospectively collected, and subsequent progress recorded. Subjects were divided into 3 groups for analysis: no dysphagia; transient dysphagia (< or =14 days); or prolonged dysphagia (>14 days). Validity of the water swallow test as a predictor of aspiration pneumonia was confirmed. Significant associations for prolonged dysphagia were seen with stroke severity, dysphasia and lesions of the frontal and insular cortex on brain imaging. These results indicate that it may be possible to predict patients who will develop prolonged significant dysphagia following acute stroke thereby facilitating referral for insertion of PEG at an earlier time point.

Acute Disease↗
PubMed2003

Ataxic arm movements after thalamotomy for Parkinsonian tremor.

Voluntary finger-nose movements of the arm were analysed in six patients undergoing stereotaxic nucleus ventralis intermedius thalamotomy for relief of severe Parkinsonian tremor. In all cases thalamotomy acutely abolished tremor in the contralateral arm. In the early postoperative phase, ataxia of the arm contralateral to the operated side was also seen. Ataxia was transient, lasting between 7 and 21 days postoperatively. This observation suggests that a lesion of the Vim nucleus interrupts cerebellar input to the thalamus, and supports the concept that abnormal cerebellar activity is an important contributor to the generation of tremor in Parkinson's disease.

Aged↗
PubMed2002

Accuracy of sampling methods in morphometric studies of human sural nerves.

The aim of this study was to ascertain the minimum sample required to accurately measure the total number of myelinated fibres, mean myelinated fibre density (MFD), myelinated fibre diameter (Ds) and axonal diameter (Da) in morphometric studies of sural nerve biopsies. Measurements were obtained by sampling a single fascicle or systematic sampling of up to 50% of the total transverse fascicular area of two control and eighteen pathological sural nerves showing varying degrees of demyelination and axonal degeneration. MFD and fibre size were heterogeneous between fascicles in both control and pathological sural nerves, and morphometric results from one fascicle and systematic sampling of up to 50% of the total transverse fascicular area did not accurately represent the whole myelinated fibre population in the sural nerve. For accurate morphometric data it is necessary to quantitate all the myelinated fibres in the sural nerve.

Adult↗
PubMed2001

6: Movement disorders II: the hyperkinetic disorders.

Involuntary movements or hyperkinesias are classified into syndromes of chorea, ballism, tremor, dystonia, myoclonus and tics. The hyperkinesias are caused by disturbances in the circuitry connecting the cerebral cortex, thalamus, basal ganglia and cerebellum. Drugs are a common cause of movement disorders. The aim of management is to characterise the movement disorder, identify and treat the cause or institute symptomatic treatment. The genetic basis of many movement disorders is increasingly recognised. Where there are potential implications for family members, accurate diagnosis and counselling are particularly important.

Humans↗
PubMed2001

5: Movement disorders I: parkinsonism and the akinetic-rigid syndromes.

The major features of akinetic-rigid syndromes are bradykinesia (small, slow movements), rigidity and tremor, often summarised as "parkinsonism". Approximately 80% of akinetic-rigid syndromes are due to Parkinson's disease. Treatment of Parkinson's disease should be determined by level of disability and handicap. The combination of levodopa and peripheral dopadecarboxylase inhibitor is the most efficacious symptomatic treatment for Parkinson's disease. Motor fluctuations appear after 2-3 years of levodopa treatment, and affect at least 50% of patients after five years. Surgery can relieve refractory tremor and dyskinesias, but does not alter disease progression or need for drug therapy.

Aged↗
PubMed2001

A novel method for correlating internal and external structure of individual myelinated nerve fibres.

A new method is described that enables longitudinal and cross sections of an individual nerve fibre to be cut at multiple specified sites along the fibre by the use of a unique marker system. In this way the internal structure of the fibre can be correlated with the external appearance. Individual myelinated nerve fibres are teased apart in epoxy resin and mounted onto a carbon-coated slide, and after orientation and marking of specific sites of interest are snap frozen to liberate the orientated and marked fibres for embedding on the surface of an epoxy resin block for subsequent longitudinal or transverse sectioning. This method is particularly useful for the correlative study of the myelin-axon relationships.

Axons↗