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Biomedical subjects

A M Bonnet

Publications and source records attributed to A M Bonnet.

At least 19 recordsLinked to original sources
PubMed1992

In-vivo SPECT imaging of D2 receptor with iodine-iodolisuride: results in supranuclear palsy.

We assessed the potential use of [123I]iodolisuride (ILIS), a new iodine ergolene derivative, to study human striatal D2 dopamine receptors with SPECT. In normal subjects, we found that the tracer accumulated preferentially in striatum. This was prevented by high doses of haloperidol. The striatal accumulation was maximal between 60 and 180 min after injection. The striatum-to-cerebellum radioactivity concentration ratio as an index of specific binding, measured 60 min after injection, was 1.52 +/- 0.19 (mean +/- s.d.) in controls and 1.36 +/- 0.11 in patients with supranuclear palsy (p less than 0.03). Our results show that ILIS may be used to study D2 receptors with SPECT. In-vivo changes of D2 receptors in human brain may be detected with this method.

Adult↗
PubMed1991

Tremor and idiopathic dystonia.

The clinical and electromyographic characteristics of tremor were studied in 45 patients presenting with various forms of idiopathic dystonia. Dystonic tremor was shown to be postural, localized, and irregular in amplitude and periodicity, absent during muscle relaxation, exacerbated by smooth muscle contraction, and associated frequently with myoclonus. Although it resembles essential tremor, dystonic tremor seems to be a distinct entity: it is more irregular with a broader range of frequencies; it is asymmetric and remains localized; myoclonus is sometimes associated. This type of tremor is most often seen in the presence of dystonia, but may be observed without evident dystonic symptoms.

Adolescent↗
PubMed1991

Does ageing aggravate parkinsonian disability?

The influence of age of onset of Parkinson's disease on the severity and the pattern of motor symptoms was investigated by comparing the motor scores with and without levodopa therapy in two groups of patients divided according to age of onset (early less than 50, late greater than 60 years) and matched for disease duration (n = 69 in each group, Study I). The baseline score, that is, the motor disability of patients when off levodopa, was similar in the early- and late- onset groups. In contrast, the residual motor score, assessed when the effect of levodopa treatment was maximum and stable, was significantly higher in the late onset group. When the two groups of patients were matched, in addition, for their residual motor score, (n = 54 in each group, Study II), no difference was observed between the early and late onset groups, except for gait disorder which was more severe in older patients. These results suggest that age of onset mainly affects the response to levodopa therapy, because it may increase the prevalence of non-dopaminergic lesions of the brain, including those responsible for gait disorders.

Age Factors↗
PubMed1989

Effects of etybenzatropine and diazepam on levodopa-induced diphasic dyskinesias in Parkinson's disease.

Levodopa-induced onset and end-of-dose dyskinesia are rare but disabling disorders. Although they can be attenuated by increasing and dividing the daily dose of levodopa, this does not constitute a therapeutic approach. In this pilot study, etybenzatropine, an anticholinergic drug, and diazepam, a selective benzodiazepine, were administered in addition to a single dose of levodopa in nine patients with Parkinson's disease. Both drugs tended to decrease the severity and the duration of onset and end-of-dose dyskinesia and to increase the duration of action of levodopa on parkinsonian symptoms.

Diazepam↗
PubMed1989

Antiparkinsonian activity of CY 208-243, a partial D-1 dopamine receptor agonist, in MPTP-treated marmosets and patients with Parkinson's disease.

The effect of stimulation of cerebral dopamine D-1 receptors by CY 208-243 on motor disability was tested in MPTP-treated parkinsonian marmosets and patients with Parkinson's disease. CY 208-243 (0.5-1.25 mg/kg s.c.) produced a dose-related reversal of akinesia and rigidity in the marmosets, lasting some 2 h. Single morning doses of CY 208-243 (5-40 mg) were compared with the usual morning dose of levodopa in eight patients with Parkinson's disease on long-term levodopa therapy who had developed motor fluctuations from immobility with akinesia and rigidity (off) to mobility often with dyskinesias (on). CY 208-243 alone was capable of switching such patients from off to on; five of the eight patients responded to the highest dose (40 mg), sometimes with dyskinesias. The response to CY 208-243 was comparable to that produced by levodopa in these cases. Drugs designed to stimulate both dopamine D1 and D2 receptors in the brain may improve the therapy of Parkinson's disease.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1989

Striatal dopamine D2 receptors in tardive dyskinesia: PET study.

The dopamine D2 receptors were investigated in vivo in eight neuroleptic-free patients with persistent tardive dyskinesia using positron emission tomography and 76Br-bromospiperone. The striatal receptor density, estimated by the striatum/cerebellum radioligand concentration ratio, was not elevated in patients as compared with age-matched controls but was positively correlated with the severity of orofacial dyskinesia assessed with the Abnormal Involuntary Movement Rating Scale. These results indicate that tardive dyskinesia is associated with normal levels of striatal D2 receptors but the severity of orofacial movements may depend on the relative density of striatal D2 receptors.

Aged↗
PubMed1989

Does cognitive impairment in Parkinson's disease result from non-dopaminergic lesions?

In order to investigate the neuronal basis of cognitive disorders in Parkinson's disease, the neuropsychological performance of 120 patients with idiopathic Parkinson's disease was analysed in relation to motor symptoms as a function of their response to levodopa. Cognitive impairment was poorly correlated with akinesia and rigidity, symptoms which respond well to levodopa treatment, and was not correlated at all with that part of the patients' motor score that could be improved by the drug. In contrast, strong correlations were found between all neuropsychological test scores and axial symptoms such as gait disorder and dysarthria, which respond little if at all to levodopa treatment. The neuropsychological test scores were also strongly correlated with the motor score of patients estimated when clinical improvement was maximal under levodopa treatment. This score is assumed to represent residual non-dopaminergic motor dysfunctions. The correlations suggest that much of the cognitive impairment in Parkinson's disease results from the dysfunction of non-dopaminergic neuronal systems.

Adult↗
PubMed1989

Cognitive slowing in Parkinson's disease fails to respond to levodopa treatment: the 15-objects test.

To evaluate clinically the slowing of cognitive processing in Parkinson's disease, we used a visual discrimination task consisting of 15 superimposed images of objects. The time needed to identify 12 objects increased by 58% in 70 patients withdrawn from levodopa treatment compared with 20 controls matched for age and education. Perceptual, motor, and psycholinguistic factors, as well as mood, only partially accounted for the slowness of performance. The 15-objects test scores of the parkinsonian patients correlated significantly with both their intellectual impairment and the severity of their parkinsonian disability, but not with the duration of the disease. The scores did not correlate with depression. Levodopa had no effect on the score, although the parkinsonian motor disability score was improved by 54%. The results indicate a cognitive slowing in Parkinson's disease which is probably related to abnormalities of nondopaminergic neuronal systems in the brain.

Adolescent↗
PubMed1988

Does levodopa aggravate Parkinson's disease?

We studied the possible deleterious effect of levodopa therapy on 185 patients with Parkinson's disease and concluded that the time when levodopa is introduced, the daily dose, and the duration of treatment do not aggravate Parkinson's disease. We also studied 72 parkinsonian patients with levodopa-induced abnormal involuntary movements to see whether early initiation of levodopa therapy affected the time of onset of abnormal involuntary movements. The results suggested that it did not, and that levodopa was started early in these patients because of the severity of their motor disability.

Female↗
PubMed1987

Cerebrospinal fluid GABA and homocarnosine concentrations in patients with Friedreich's ataxia, Parkinson's disease, and Huntington's chorea.

Free and total gamma-aminobutyric acid (GABA) and homocarnosine concentrations were measured in the lumbar cerebrospinal fluid (CSF) of patients with Friedreich's ataxia, Huntington's chorea, and Parkinson's disease (with and without levodopa treatment), and compared with those determined in control subjects. Values found in Friedreich's ataxia or Parkinson's disease were not significantly different from those in controls. Unexpectedly, in Huntington patients, known to have a characteristic decrease in GABA concentrations in specific brain areas, CSF concentrations of total GABA and homocarnosine were significantly higher, whereas free GABA was not different from controls. These findings indicate that the measurement of CSF GABA and homocarnosine in patients with CNS degenerative diseases should be interpreted cautiously.

Adult↗
PubMed1987

Acetylcholinesterase and butyrylcholinesterase activity in the cerebrospinal fluid of patients with neurodegenerative diseases involving cholinergic systems.

Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) were assayed in the cerebrospinal fluid (CSF) of subjects with neurodegenerative diseases (dementing and non-dementing, with and without known cholinergic lesions), to determine whether CSF AChE is a valid marker of central cholinergic activity. The relative proportions of the different forms of each enzyme and of AChE to BChE were similar in CSF and brain. AChE decreased in Huntington's chorea (degeneration of striatal cholinergic interneurons) but also in multiple sclerosis (not known to affect cholinergic systems). BChE paralleled AChE, although the enzymes were dissociated in some patients. It is concluded that CSF AChE activity may globally reflect brain AChE, but pathology-induced changes may not be directly reflected.

Acetylcholinesterase↗
PubMed1987

Does long-term aggravation of Parkinson's disease result from nondopaminergic lesions?

The motor score with and without levodopa was estimated in 193 parkinsonian patients with variable length of evolution. The effect of levodopa on akinesia, rigidity, and tremor remained quite stable during the course of the disease. In contrast, the aggravation of gait disorder, postural instability, and dysarthria was more severe, with decreased percentage of improvement on levodopa in patients with longer evolution. It is suggested that aggravation of Parkinson's disease mainly results from increasing severity of cerebral nondopaminergic lesions.

Brain↗
PubMed1986

Acetylcholinesterase and butyrylcholinesterase in frontal cortex and cerebrospinal fluid of demented and non-demented patients with Parkinson's disease.

The molecular forms of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) were studied in frontal cortex (grey and white matter), postmortem, and in cerebrospinal fluid (CSF) of demented patients with Parkinson's disease compared to controls and non-demented parkinsonians. In the frontal cortex, AChE activity decreased significantly in both demented and non-demented parkinsonian subjects compared to controls; the 10S form of the enzyme was significantly lower in demented parkinsonians than in the non-demented subjects. The decrease in AChE activity was correlated with a decrease in choline acetyltransferase activity thought to reflect lesion of cholinergic neurones in the substantia innominata which innervate the cerebral cortex. BChE activity decreased only in the non-demented parkinsonians; in the demented subjects, BChE activity was at control levels. Similar results were obtained with grey and white matter, although absolute levels of the two enzymes were different in the two types of tissue, suggesting that the enzymes were affected in the cholinergic neurones before transport to cortical nerve terminals. No decreases in AChE or BChE activity were observed in the CSF of the patients studied. On the contrary, AChE and BChE levels were significantly higher in demented parkinsonian patients compared to the non-demented subjects.

Acetylcholinesterase↗