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Biomedical subjects

A J Lees

Publications and source records attributed to A J Lees.

At least 181 records · Page 10Linked to original sources
PubMed1994

Nitric oxide synthase mRNA expression in human subthalamic nucleus, striatum and globus pallidus: implications for basal ganglia function.

The distribution of NOS mRNA within human basal ganglia was investigated using in situ hybridisation histochemistry (ISHH). Greater than 95% of subthalamic nucleus neurons were NOS mRNA-positive, between 1.5% and 2% of striatal neurons were positive and scattered NOS mRNA-positive neurons were detected in the medial, but not lateral globus pallidus. Levels of NOS mRNA expression per neuron were considerably higher in the striatum than in the pallidum or subthalamus. These findings have implications for basal ganglia function and disease states.

Amino Acid Oxidoreductases↗
PubMed1994

Cognitive deficits in progressive supranuclear palsy, Parkinson's disease, and multiple system atrophy in tests sensitive to frontal lobe dysfunction.

Groups of patients with idiopathic Parkinson's disease, multiple system atrophy, and progressive supranuclear palsy or Steele-Richardson-Olszewski syndrome, matched for overall clinical disability, were compared using three computerised cognitive tests previously shown to be sensitive to frontal lobe dysfunction. On a test of planning based on the Tower of London task, all three groups were impaired, but in different ways. The groups with palsy and Parkinson's disease were slower in the measure of initial thinking time, whereas the group with multiple system atrophy was only slower in a measure of thinking time subsequent to the first move, resembling patients with frontal lobe damage. On a test of spatial working memory, each group showed deficits relative to their matched control groups, but the three groups differed in their strategy for dealing with this task. On a test of attentional set shifting, each group was again impaired, mainly at the extradimensional shifting stage, but the group with Steele-Richardson-Olszewski syndrome exhibited the greatest deficit. The results are compared with previous findings in patients with Alzheimer's disease or frontal lobe damage. It is concluded that these basal ganglia disorders share a distinctive pattern of cognitive deficits on tests of frontal lobe dysfunction, but there are differences in the exact nature of the impairments, in comparison not only with frontal lobe damage but also with one another.

Aged↗
PubMed1994

Absence of disease related prion protein in neurodegenerative disorders presenting with Parkinson's syndrome.

Movement disorders presenting with parkinsonism may share histopathological features with Creutzfeldt-Jakob disease, a spongiform encephalopathy caused by the accumulation of pathological prion protein in brain. To investigate a possible aetiological link between these conditions and Creutzfeldt-Jakob disease, histoblot immunostaining for pathological prion protein was carried out in 90 cases including idiopathic Parkinson's disease, multiple system atrophy, diffuse Lewy body disease, Steele-Richardson-Olszewski syndrome, corticobasal degeneration, and Pick's disease. Pathological prion protein was identified in four controls with Creutzfeldt-Jakob disease but not in any of the other diseases examined. The findings suggest that an aetiological role for prions in these movement disorders is unlikely. Histoblotting provides a useful method for screening large areas of tissue for the presence of pathological prion protein and may be helpful in the differential diagnosis of difficult cases.

Brain↗
PubMed1994

HMPAO SPECT in Parkinson's disease before and after levodopa: correlation with dopaminergic responsiveness.

Regional cerebral perfusion was evaluated by SPECT with technetium 99m hexamethylpropyleneamine oxime (99mTc HMPAO) as a tracer in 21 patients presenting with Parkinson's disease and in 11 normal controls. In the parkinsonian patients, scans were performed both off treatment, and after levodopa, and clinical dopaminergic responsiveness was evaluated. Uptake of HMPAO by the basal ganglia was significantly decreased in the parkinsonian subjects, compared with normal controls. This reduction was seen in both responders (n = 14) and non-responders (n = 7) to dopaminergic treatment. Uptake of HMPAO by the basal ganglia rose after treatment with levodopa, but the change was similar in both responders and non-responders. By contrast a striking difference in cortical HMPAO uptake was found between responders and non-responders, with significantly lower uptake in the medial temporal and posterior parietal cortex in the non-responders. This reduction was symmetrical. Basal ganglia perfusion assessed by this technique is unlikely to be of use in the diagnosis of Parkinson's disease that is responsive to dopaminergic treatment. The presence of extensive cortical involvement on a baseline scan correlates with a lack of dopaminergic responsiveness, however, and this may be useful diagnostically.

Aged↗
PubMed1994

Effect of entacapone, a peripherally acting catechol-O-methyltransferase inhibitor, on the motor response to acute treatment with levodopa in patients with Parkinson's disease.

Catechol-O-methyltransferase (COMT) inhibitors may be useful in the treatment of Parkinson's disease by improving the bioavailability of levodopa and by prolonging its effects. Entacapone (OR-611), a novel COMT inhibitor, which does not cross the blood brain barrier, was assessed in 12 patients with Parkinson's disease and motor fluctuations in a randomised, double-blind, cross-over, single dose study. The magnitude and duration of the therapeutic response to a single dose of 200 mg levodopa/50 mg carbidopa was evaluated after concomitant placebo, or 200 or 800 mg entacapone. A significant increase in the duration of the motor response to levodopa was seen when 200 mg entacapone was given with levodopa/carbidopa. Plasma levodopa concentrations were increased with both doses of the COMT inhibitor. The latency to onset of motor response did not differ significantly between active drug and placebo. Entacapone may prove useful in prolonging the duration of the benefit obtained from individual doses of levodopa.

Aged↗
PubMed1994

Motor response to levodopa in patients with parkinsonian motor fluctuations: a follow-up study over three years.

To clarify the way in which the clinical response to levodopa changes with the progression of Parkinson's disease, a longitudinal study was performed to quantify motor response characteristics to single doses of levodopa by mouth over three years in 23 patients with fluctuating motor function. A significant increase in motor disability in "on" (time of peak motor improvement) and "off" (before levodopa dose) phases occurred and "on" phase dyskinesia increased by 24%, though the amplitude of motor response was conserved. There was no evidence of progressive loss of response of certain motor deficits affecting axial muscles and gait. The mean duration of motor response decreased by 17%. Both shortening of response duration and increase in "off" phase disability contribute to the development of motor fluctuations. A short response time to the levodopa test dose was not an invariable finding in patients with severe fluctuations, whereas all had large response amplitudes and high "off" phase disability scores. Patients who have developed motor fluctuations may continue to respond to dopaminergic treatment until late in the disease course, despite the unstable nature of their responses.

Adult↗
PubMed1994

The nature of apraxia in corticobasal degeneration.

Although apraxia is one of the most frequent signs in corticobasal degeneration, the phenomenology of this disorder has not been formally examined. Hence 10 patients with corticobasal degeneration were studied with a standardised evaluation for different types of apraxia. To minimise the confounding effects of the primary motor disorder, apraxia was assessed in the least affected limb. Whereas none of the patients showed buccofacial apraxia, seven showed deficits on tests of ideomotor apraxia and movement imitation, four on tests of sequential arm movements (all of whom had ideomotor apraxia), and three on tests of ideational apraxia (all of whom had ideomotor apraxia). Ideomotor apraxia significantly correlated with deficit in both the mini mental state examination and in a task sensitive to frontal lobe dysfunction (picture arrangement). Two of the three patients with ideomotor apraxia and ideational apraxia showed severe cognitive impairments. The alien limb behaviour was present only in patients with ideomotor apraxia. In conclusion, ideomotor apraxia is the most frequent type of apraxia in corticobasal degeneration, and may be due to dysfunction of the supplementary motor area. There is a subgroup of patients with corticobasal degeneration who have a severe apraxia (ideomotor and ideational apraxia), which correlates with global cognitive impairment, and may result from additional parietal or diffuse cortical damage.

Aged↗
PubMed1994

PET studies of the presynaptic and postsynaptic dopaminergic system in Tourette's syndrome.

Dysfunction of the dopaminergic pathway has been postulated to underlie the symptomatology of Tourette's syndrome. Presynaptic functional integrity of dopaminergic terminals was assessed with 18F-dopa PET in 10 patients with Tourette's syndrome, three of whom were drug free and seven of whom were on neuroleptic treatment. Dopamine D2 receptor site density was measured with 11C-raclopride PET in a further group of five drug free patients with Tourette's syndrome. Mean caudate and putamen 18F-dopa influx constants were similar in patients with Tourette's syndrome and controls, and there was no difference in striatal 18F-dopa uptake between the treated and untreated Tourette's syndrome groups. Mean caudate and putamen 11C-raclopride binding potentials in patients with Tourette's syndrome were also similar to control values. The findings suggest that striatal metabolism of exogenous levodopa and the density of striatal D2 receptors are both normal in patients with Tourette's syndrome and that Tourette's syndrome does not arise from a primary dysfunction of dopaminergic terminals.

Adolescent↗
PubMed1994

Micrographia associated with a parietal lobe lesion in multiple sclerosis.

The occurrence of micrographia in a 52 year old women two years after an isolated episode of painful sensory disturbance led to the diagnosis of multiple sclerosis. Her handwriting returned to normal after a course of intravenous methylprednisolone. Previous reports of movement disorders occurring in the context of multiple sclerosis are briefly reviewed. The finding on MRI studies of an enhancing lesion in the dominant parietal white matter supports Kinnier Wilson's suggestion that the anatomical origin of micrographia lies in the cerebral hemisphere rather than the corpus striatum.

Brain Diseases↗
PubMed1994

The concept of bradyphrenia.

The historical interplay between akinesia, bradyphrenia and psychomotor retardation is reviewed. It is concluded that bradyphrenia is a common accompaniment to the motor disabilities of Parkinson's disease and consists of slowness of thought, impaired attention and motivation, lack of spontaneity, inflexibility and forgetfulness. Impaired attentional extra-dimensional set-shifting may be responsible for many of these problems. Some clinical overlap occurs between Parkinson's disease, severe depressive illness and obsessional-compulsive disorder and it is proposed that there may be shared biological disturbances involving basal-ganglia-limbic-frontal circuits in the three conditions.

Cognition Disorders↗
PubMed1993

A clinicopathologic study of 100 cases of Parkinson's disease.

The clinical details of 100 cases of histologically confirmed Parkinson's disease were examined and correlated with pathologic findings. Age at disease onset (mean, 62.4 years), disease duration (mean, 13.1 years), and age at death (mean, 75.5 years) were similar to those in previous smaller series. Asymmetric, tremulous onset was most common, although 23% of patients had no rest tremor. Motor fluctuations and dyskinesias occurred in 60% of levodopa-treated patients. All patients had clinical parkinsonism; however, 12 had atypical clinical features of Parkinson's disease, including severe early dementia, fluctuating confusional states, no response to levodopa, and early marked autonomic disturbance. Neuropathologic examination found coexistent Alzheimer-type change in 17 cases and striatal abnormality--mainly vascular--in 34 cases. Cortical Lewy bodies were present in all cases, but only four satisfied proposed criteria for diffuse Lewy body disease. Dementia occurred in 44% of cases; 29% had Alzheimer's disease, 10% had numerous cortical Lewy bodies, and 6% had a possible vascular cause; in 55% no definite pathologic cause was found. Nigral cell loss correlated with disease duration and severity. Although the general pattern of disease conformed to traditional descriptions, the findings broaden the present clinical and pathologic spectrum of Parkinson's disease.

Adult↗
PubMed1993

Subcutaneous apomorphine in Parkinson's disease: response to chronic administration for up to five years.

Subcutaneous apomorphine, administered by continuous waking-day infusion with boluses, or by repeated intermittent injection, was given to 71 parkinsonian patients with severe refractory levodopa related on-off fluctuations for 1-5 years. A mean reduction in daily off period time of approximately 50% was maintained, and the incidence of neuropsychiatric toxicity remained low on long-term follow-up. No clinically significant tolerance or loss of therapeutic effect was seen, although increasingly severe on-phase dyskinesias and postural instability marred the long-term therapeutic response in many patients. Despite these drawbacks, apomorphine, when combined with the peripheral dopamine receptor agonist domperidone, represents a significant therapeutic advance in the management of late-stage Parkinson's disease and should certainly be considered before experimental implantation procedures.

Adult↗
PubMed1993

Inverse masticatory muscle activity due to syringobulbia.

The clinical, radiological, and electrophysiological data of a 25-year-old woman with "inverse masticatory muscle activity" due to syringobulbia is presented. This uncommon brain stem syndrome may be due to a disturbance in central programming of mastication.

Adult↗
PubMed1993

Pathological overlap in cases of parkinsonism associated with neurofibrillary tangles. A study of recent cases of postencephalitic parkinsonism and comparison with progressive supranuclear palsy and Guamanian parkinsonism-dementia complex.

In recent years a number of patients suffering from long-standing postencephalitic parkinsonism have donated their brains to the United Kingdom Parkinson's Disease Society Brain Bank, in London. In view of the paucity of detailed neuropathological reports of the disease since the 1940s, we have carried out a clinicopathological study of eight recent cases. A spectrum of pathological change was seen, with highly variable involvement of cortical, subcortical and brainstem structures. There was no correlation between severity of disease and severity of pathology. The anatomical distribution of lesions was compared with that seen in progressive supranuclear palsy and Guamanian Parkinson-dementia complex. No definite histological features were identified that could distinguish any of the three disease entities. While the pathogenesis of postencephalitic parkinsonism, progressive supranuclear palsy and Guamanian Parkinson-dementia complex remains unknown, the presence of similar pathologies in these conditions suggests a common disease mechanism, despite the distinctive clinical features.

Aged↗
PubMed1993

Dopamine agonists in Parkinson's disease: a look at apomorphine.

Apomorphine is a D1 and D2 dopamine receptor agonist with anti-parkinsonian properties qualitatively similar to those seen with L-dopa. It was first used in the treatment of Parkinson's disease by Schwab in the 1950s but owing to its short duration of action, the need for parenteral administration, and adverse reactions including nausea, vomiting, postural hypotension and sedation, it was not widely prescribed. In the early 1970s, Cotzias confirmed its potent anti-parkinsonian effects and that some of its secondary effects were diametrically opposite to those seen with L-dopa. The advent of peripheral dopamine receptor antagonist drugs, which counteract the unwanted effects of apomorphine, and the development of new drug delivery systems including insulin pens and ambulatory mini pumps have led to the resurrection of apomorphine for the treatment of Parkinson's disease. Over the last five years in Europe, the drug has proved to be a major advance in the treatment of refractory "on-off" oscillations in Parkinson's disease. It has also been used as a diagnostic test for dopaminergic responsiveness in Parkinson syndromes and tremors of uncertain aetiology. The drug has also proved particularly useful in dealing with certain "off-period" disabilities, including pain, bladder dysfunction, dystonia and gastro-intestinal symptoms. Continuous steady state infusion of apomorphine by mini-pump may reduce the severity of "on" phase dyskinesias over time. The drug has also proved useful in the clinical pharmacological investigation of the pathophysiology of the motor response to dopaminergic drugs in Parkinson's disease and the occurrence of involuntary movement sequences. Neuropsychiatric side-effects are relatively infrequent when compared with ergolene dopamine agonists.(ABSTRACT TRUNCATED AT 250 WORDS)

Apomorphine↗