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Biomedical subjects

I Shoulson

Publications and source records attributed to I Shoulson.

At least 55 records · Page 3Linked to original sources
PubMed1988

NMDA receptor losses in putamen from patients with Huntington's disease.

N-Methyl-D-aspartate (NMDA), phencyclidine (PCP), and quisqualate receptor binding were compared to benzodiazepine, gamma-aminobutyric acid (GABA), and muscarinic cholinergic receptor binding in the putamen and cerebral cortex of individuals with Huntington's disease (HD). NMDA receptor binding was reduced by 93 percent in putamen from HD brains compared to binding in normal brains. Quisqualate and PCP receptor binding were reduced by 67 percent, and the binding to other receptors was reduced by 55 percent or less. Binding to these receptors in the cerebral cortex was unchanged in HD brains. The results support the hypothesis that NMDA receptor-mediated neurotoxicity plays a role in the pathophysiology of Huntington's disease.

Cerebral Cortex↗
PubMed1988

Atrophy of medium spiny I striatal dendrites in advanced Parkinson's disease.

Loss of dopaminergic neurons from the pars compacta of the substantia nigra is the pathological hallmark of Parkinson's disease (PD) and results in a partial deafferentation to the striatum. Since deafferentation is known to induce transynaptic atrophy of postsynaptic cells, we examined by Golgi impregnation the morphology of medium spiny I (MSI) striatal neurons, the principal target population for both nigrostriatal and corticostriatal fibers. Our quantitative data indicate that the dendritic arbor of MSI neurons in the putamen is significantly reduced in both length and number and MSI neurons are morphologically characterized by truncated dendrites with few dendritic spines and irregular, bulbous swellings. These data provide morphological evidence for the atrophy of striatal dendrites in PD and may explain, in part, the declining efficacy of chronic L-DOPA replacement therapy in advanced PD.

Aged↗
PubMed1988

Cerebrospinal fluid correlates of depression in Huntington's disease.

Patients with Huntington's disease (HD) commonly have concomitant depressive disorders. Prompted by reports of elevated corticotropin releasing factor (CRF) and reduced 5-hydroxyindoleacetic acid (5-HIAA) concentrations in lumbar cerebrospinal fluid (CSF) of patients with major depression, these CSF constituents were examined in 56 nonmedicated patients who were in the early stages of HD. Elevated CRF concentrations were found in patients with HD in comparison with a control group of 21 subjects without neurologic illness. The CSF 5-HIAA concentrations in patients with HD did not differ from that in four normal volunteers. Patients with HD who had depressive disorders (major depression or dysthymia) did not differ from those without depression with respect to CSF 5-HIAA or CRF concentration. However, a positive correlation was observed between severity of major depression and CRF concentration. These findings suggest that the depression associated with HD may differ neurochemically from that seen in other major depressive disorders, and support the notion that clinically significant depressive symptoms reflect heterogeneous pathophysiologic conditions with different neurochemical correlates.

Adult↗
PubMed1988

Duodenal and gastric delivery of levodopa in parkinsonism.

To clarify the influence of gastric emptying on levodopa-related motor fluctuations in Parkinson's disease, we assessed mobility and plasma levodopa concentrations in 10 patients during five modes of levodopa administration: (1) standard intermittent oral (SIO), (2) intermittent duodenal (ID), (3) continuous duodenal infusion (CDI), (4) continuous gastric infusion (CGI), and (5) controlled-release Sinemet (CR-4). The rank order from greatest to least for both percentage of time "on" and average mobility score was CDI, CGI, ID, CR-4, and SIO. The rank order for variance of means, a measure of fluctuation, from least to greatest for mobility was CDI, CGI, CR-4, ID, SIO, and for plasma levodopa concentrations was CDI, CGI, ID, SIO, and CR-4. The results demonstrate that it is possible to produce very steady plasma concentrations of levodopa with a corresponding reduction in motor fluctuations by continuous intraduodenal administration of the drug. This mode of delivery is an ideal model for the development of optimal continuous-release preparations of levodopa. Other enteral routes have produced a more variable plasma levodopa concentration and clinical response.

Administration, Oral↗
PubMed1988

Cerebrospinal fluid homovanillic acid and parkinsonism in Huntington's disease.

In Huntington's disease (HD), normal or decreased levels of homovanillic acid (HVA) in cerebrospinal fluid (CSF) have been reported but have not been analyzed with respect to severity of parkinsonism, which in certain cases may be a predominant feature of the illness. We obtained CSF by lumbar puncture from four groups of nonmedicated subjects: (1) those with HD in the earliest stages of illness (n = 51), (2) those with parkinsonism, including idiopathic (n = 10) and atypical forms (n = 4), (3) those with nonparkinsonian movement disorders (n = 19), and (4) normal volunteers (n = 4). HVA was determined by high-pressure liquid chromatography with electrochemical detection, and motor signs were assessed in standardized fashion. The parkinsonian group had reduced levels of CSF HVA, but the other groups showed no significant differences. For those with HD, no correlation was found between HVA level and severity of parkinsonism, and there were no differences in HVA level between those subjects with (n = 14) or without (n = 37) prominent parkinsonism or between subjects whose age at illness onset was 30 years or less (n = 16) and those whose age at onset was over 30 (n = 35). Our findings indicate that in early, untreated HD, CSF HVA is in the normal range and does not correlate with the severity of parkinsonism. This observation supports neuropathological findings suggesting that parkinsonian features in HD are largely related to the loss of postsynaptic striatal dopamine receptors rather than to presynaptic nigral degeneration.

Adult↗
PubMed1988

Cerebrospinal fluid levels of quinolinic acid in Huntington's disease and schizophrenia.

The concentration of the endogenous excitotoxin quinolinic acid was determined in the cerebrospinal fluid of drug-free patients suffering from Huntington's disease or schizophrenia (control group). In both diseases, quinolinic acid concentrations were highly variable (less than 4-48 nM) but the mean levels for each disease group were not significantly different from each other or from the quinolinic acid concentration of normal cerebrospinal fluid. Analysis of steady-state cerebrospinal fluid quinolinic acid concentration is unlikely to be of value as a diagnostic tool in Huntington's disease.

Adolescent↗
PubMed1988

Erratic gastric emptying of levodopa may cause "random" fluctuations of parkinsonian mobility.

The pathogenesis of "random" fluctuations in parkinsonian mobility, which are not clearly related to the dosing schedule of levodopa, has not been determined. We rated parkinsonian mobility and assayed plasma dopa in one patient with clinically random fluctuations during two modes of administration of levodopa/carbidopa: (1) standard oral route and (2) direct duodenal delivery via nasoduodenal tube. During oral therapy, mobility varied unpredictably in relation to levodopa dosing, suggesting a clinically random pattern. During duodenal delivery, however, a predictable and dramatic pattern of recurrent end-of-dose deterioration was observed; each intraduodenal levodopa dose resulted in 60 to 90 minutes of benefit. Plasma dopa levels correlated closely with mobility ratings for both modes of administration. Our findings indicate that erratic gastric emptying of levodopa is responsible for apparently "random" oscillations in mobility in at least one patient with Parkinson's disease and probably in others.

Absorption↗
PubMed1987

Severity of Tourette's syndrome in one large kindred. Implication for determination of disease prevalence rate.

An accurate prevalence rate for Tourette's syndrome (TS) has not been established. To assess severity of illness, a potential source of bias in determining prevalence rate, we administered standardized questionnaires and examinations to 159 members of a large Mennonite kindred showing apparent autosomal dominant transmission of motor and vocal tics (TS) or chronic motor tics (CMTs). Fifty-four family members were diagnosed as having definite or probable TS or CMTs. For these 54 subjects, 30% (n = 16) were unaware of tics noted by the examiners and only 18.5% (n = 10) had sought medical care. Our findings suggest that most cases of TS and CMTs are mild and do not come to medical attention. These tic disorders are probably much more prevalent than generally appreciated.

Adolescent↗
PubMed1987

Coexistent Meige's syndrome and myasthenia gravis. A relationship between blinking and extraocular muscle fatigue?

We studied five patients with a combination of Meige's syndrome (blepharospasm-oromandibular dystonia) and myasthenia gravis. The coexistence of two disorders impairing eyelid opening led to diagnostic confusion and delayed appropriate therapy. Detailed oculographic monitoring of one patient indicated that eye position drifting due to myasthenic oculomotor fatigue was corrected by eye blinks, and that blinks tended to occur with slower saccades. Our observations suggest that fatigue of extraocular muscles may lead to synkinetic blinking and perhaps eventually to autonomous blepharospasm.

Aged↗
PubMed1987

Familial paroxysmal dystonic choreoathetosis: a family study.

We interviewed and examined 12 members of a single family affected by paroxysmal dystonic choreoathetosis. Three subjects experienced characteristic painful dystonic spasms, often precipitated by cold and prolonged physical activity. Three other family members suffered painful cramping of their limbs, without involuntary movement, following physical exertion. Based on the clinical features of affected subjects, we suggest that exertional cramping may represent a "forme fruste" of paroxysmal dystonia.

Adolescent↗
PubMed1987

Hereditary myoclonus and chorea: the spectrum of hereditary nonprogressive hyperkinetic movement disorders.

We report three members of a single family who developed a newly described combination of myoclonus and chorea in association with mild ataxia. The occurrence of this and related syndromes suggests that inherited, slowly progressive myoclonus, chorea, and dystonia, alone or in combination, should be viewed as a spectrum of hyperkinetic involuntary movements, and that each motor component may represent variable expression of the same genetic defect.

Adult↗
PubMed1987

Tissue culture evidence for a circulating neurotoxin in Huntington's chorea.

We explored with tissue culture techniques the possibility that a circulating neurotoxin might cause the premature loss of certain populations of neurons that characterizes Huntington's chorea (HC). Explants of striatum from newborn rats were grown in culture media containing 30% by volume of serum from drug-free HC patients or from healthy control subjects. Glutamic acid decarboxylase (GAD), the enzyme which synthesizes gamma-aminobutyric acid (GABA), was later assayed in these explants as an indicator of the health of GABAergic striatal neurons. The sera of 7 of 8 HC patients decreased GAD activity markedly when present as 30% of the tissue culture medium. When present in lower concentration (15%), HC sera either decreased or increased GAD activity in explants. Deproteinization of sera with perchloric acid did not abolish these effects on GAD activity. A depressant effect on GAD activity was detected in the cerebrospinal fluid of 1 of 4 HC patients tested. These experiments suggest the presence of a circulating neurotoxin, possibly excitotoxic to GABAergic striatal interneurons, and probably a small molecule. Identification of this substance could lead to an effective preventive treatment for persons genetically at risk for HC.

Adolescent↗
PubMed1986

A controlled neuropsychological comparison of Huntington's disease and multiple sclerosis.

This study compared the intellectual deficits of patients who had the earliest stages of Huntington's disease (HD) with those of mildly or moderately affected patients suffering from multiple sclerosis; both groups were matched for age, education, and ability to function. Twenty-one HD patients, 30 multiple sclerosis subjects, and 15 matched controls were evaluated neuropsychologically; all were free of psychoactive medications. The two patient groups showed similar overall patterns of impairment, though the HD group had greater verbal and nonverbal memory deficits. The HD patients also demonstrated significant dyscalculia and showed indications of developing problems in language usage and copying. These results are discussed in light of each disorder's neuropathologic substrate.

Adult↗
PubMed1986

Duodenal delivery of levodopa for on-off fluctuations in parkinsonism: preliminary observations.

The pathogenesis of on-off motor fluctuations in parkinsonism remains incompletely understood, but slowed or erratic gastric emptying of orally administered levodopa may be involved. In 3 patients with resistant on-off fluctuations, direct duodenal continuous infusion of levodopa via a nasoduodenal tube resulted in a heightened therapeutic effect, including a reduction in motor fluctuations. In 1 of these patients, continuous duodenal levodopa infusion produced greater benefit than did intermittent duodenal levodopa administration. Direct duodenal delivery of levodopa lessens the problems with gastric emptying and may be suitable for long-term therapy in selected patients with resistant on-off motor fluctuations.

Adult↗