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Biomedical subjects

C N Karson

Publications and source records attributed to C N Karson.

At least 55 records · Page 3Linked to original sources
PubMed1987

Preliminary evidence of reduced combined output of dopamine and its metabolites in chronic schizophrenia.

The mean combined total body excretion of dopamine (DA) and its metabolites, measured by summing the molar excretion of DA and its metabolites in 24-hour urine samples (Sum DA), was reduced in 20 patients with schizophrenia who had not been receiving medication for at least two weeks. These patients were relatively resistant to treatment, as they were unable to live independently outside institutional settings despite conventional neuroleptic therapy. In contrast, sum norepinephrine (Sum NE), measured by summing the molar excretion of NE and its metabolites, was not reduced. These results are highlighted by expressing the data in terms of the ratio of Sum DA/Sum NE. Patients with schizophrenia had a significantly lower ratio. Treatment with haloperidol normalized the low ratio. Urinary excretion of 5-hydroxyindoleacetic acid was normal in the schizophrenic patients. These results suggest that chronic schizophrenia is more likely to be associated with a low rather than a high state of DA activity.

Adult↗
PubMed1987

The effect of metoclopramide on the Ganzfeld electroretinogram.

Antecedent light flashes enhance the amplitude of the electroretinogram (ERG) oscillatory potentials, but do not modify other ERG responses nor dark-adaptation sensory thresholds. Metoclopramide infusion (i.v.) has a generally attenuating effect on the ERG, which is more evident under conditions of dark- than light-adaptation. Metoclopramide decreases the peak amplitude of the rod b-wave and the dark-adapted cone b-wave in a similar manner; it also significantly increases the implicit time of the rod b-wave, but not of the dark-adapted cone b-wave. In addition metoclopramide reverses the enhancement of the oscillatory potentials by the antecedent light flashes.

Action Potentials↗
PubMed1987

Ganzfeld electroretinographic findings in parkinsonism: untreated patients and the effect of levodopa intravenous infusion.

Two groups of patients with primary Parkinsonism were studied with the ganzfeld electroretinogram (ERG): seven patients who had never received dopamimetic agents, and six patients given an infusion of levodopa following a period of medication withdrawal. Patients in the first category had a subtle increase in the latency of their short-wavelength sensitive cone response recorded from the retina ipsilateral to their more symptomatic side. Most patients in the second category demonstrate an improvement in their ERG when the responses recorded following levodopa infusion were compared with baseline responses obtained during the period of medication withdrawal. These results suggest that one role of retinal dopamine may be maintenance of normal retinal responsiveness to flash stimuli.

Electroretinography↗
PubMed1986

Increased blink rate in adolescent patients with psychosis.

Increased blink rate, a putative correlate of central dopaminergic activity, may be elevated in patients with chronic schizophrenia. In an effort to determine whether this elevation is due to iatrogenic factors, blinking was examined in medication-naive adolescent psychiatric inpatients undergoing their first hospitalization. The mean (+/- SD) blink rate of patients with psychosis (n = 13, 16 +/- 9 blinks/minute) was significantly greater than that of the nonpsychotic control inpatients (n = 35, 10 +/- 6 blinks/minute). Thus, elevated blink rate may be a feature of psychosis that is not necessarily caused by neuroleptic treatment or psychiatric hospitalization.

Adolescent↗
PubMed1986

The paranoid quotient. A BPRS ratio for exploring subtypes in schizophrenia.

A paranoid quotient developed from two items of the Brief Psychiatric Rating Scale, suspiciousness and disorganized speech, is presented as a novel method for estimating the degree of paranoia of chronic schizophrenic patients. The mean quotient for paranoid schizophrenic patients was 70 which significantly exceeded that of non-paranoid patients (mean quotient = 47, P less than 0.002). This difference proved more discriminatory than that obtained by examining the constituent items alone. Hence, the quotient strategy offers a promising way to quantify paranoid symptoms in a population of patients in whom diagnostic subtyping is often difficult.

Adult↗
PubMed1986

Treatment of schizophrenia with a vasopressin analogue.

Ten patients with chronic schizophrenia completed a 3-month double-blind, placebo-controlled trial with a vasopressin analogue. Modest improvement occurred, but several patients also experienced significant fluid and electrolyte imbalance.

Adolescent↗
PubMed1986

Alpha-adrenergic receptors and cyclic AMP production in a group of schizophrenic patients.

Alpha 2-adrenergic receptor function was measured in platelets from chronic schizophrenic patients and normal controls. The number of alpha 2-receptors was greater in patients' platelets, and the prostaglandin E1 (PGE1)-stimulated cyclic AMP (cAMP) production lower, when compared with the normal controls. The changes measured may occur only in the platelet, but if central nervous system neurons share with platelets these changes, one might speculate that an increase in the number of alpha 2-receptors and a decrease in cAMP production may relate to the psychopathology of schizophrenia.

Adult↗
PubMed1985

Increased urine volume in chronic schizophrenic patients.

Polydipsia and polyuria have a long association with schizophrenia. To assess the prevalence of polydipsia and polyuria in schizophrenia, urine volume was examined in medication-free chronic schizophrenic patients, normal controls, and nonschizophrenic patients. Mean urine volume was significantly higher in the schizophrenic patients (2319 +/- SD 2052 ml/24 hours) than in the other two groups (1054 +/- SD 471 ml/24 hours for nonschizophrenic patients and 1265 +/- SD 613 ml/24 hours for normals). Seven of 35 patients with schizophrenia but 0/7 nonschizophrenics had urine volumes greater than any normal control. Polyuria was associated with a good premorbid history and a positive neuroleptic response. Among polyuric patients, those with hyponatremia may represent a different, distinct subgroup. Neuroleptic treatment was associated with a further, significant increase in urine volume. Hence, polydipsia and polyuria appear to be relatively common in schizophrenia.

Adult↗
PubMed1985

Eye-blink rate in Tourette's syndrome.

Gilles de la Tourette's syndrome is a hyperkinetic movement disorder in which an etiological role for dopaminergic hyperactivity has been proposed. Blink rate, a putative correlate of central dopamine activity, is commonly held to be elevated in Tourette's syndrome, a finding that would be consistent with the "dopamine" hypothesis of this disorder. In 19 patients who had Tourette's syndrome, however, blink rates during placebo treatment were identical with those of 49 index controls during reading and quiet sitting. Blink rate did correlate, however, with both the number and severity of tics. Pimozide treatment did not reduce blinking in the patients. It should be noted that nine of the patients were adolescents for whom there were not adequate age-matched controls, a fact which could obscure a blink rate elevation in this group. Insofar as blink rate is a putative correlate of central dopamine activity, these results are not consistent with elevated brain dopamine activity in adult patients who have Tourette's syndrome.

Adolescent↗
PubMed1984

Seasonal variation in human central dopamine activity.

This report focuses on two studies of seasonal variation of central dopamine activity in patients with schizophrenia and normal controls. In the two investigations, data were grouped and analyzed by season (i.e., spring-summer vs. fall-winter). The first study concerned blink rate, a putative measure of central dopamine activity; the blink rate for patients with schizophrenia was significantly increased during the spring-summer period. In the second study concentrations of catecholamines and their metabolites were measured in the hypothalamus and nucleus accumbens of normal and schizophrenic subjects. Findings include a reduced concentration of hypothalamus dopamine in normal controls and a reduced concentration of homovanillic acid in the nucleus accumbens of patients with schizophrenia, both during the spring-summer period.

Adult↗
PubMed1984

The Genain Quadruplets: electrophysiological, positron emission, and X-ray tomographic studies.

Four 51-year-old monozygotic quadruplets concordant for schizophrenia, originally studied at the National Institute of Mental Health 25 years ago, were restudied with topographic electroencephalography (EEG), evoked potentials (EPs), computed tomography (CT scans), polysomnographic sleep recordings, and positron emission tomography (PET) with 18F-2-deoxyglucose. EEG and EP findings were consistent with those from other groups of patients with schizophrenia and showed great similarity within the quadruplets. CT scans revealed uniformly small lateral ventricles. PET scans replicated earlier findings of relatively low glucose use in the frontal lobes but did not show strong familial concordance.

Brain↗
PubMed1984

Eye-blinking and cerebral ventricular size in chronic schizophrenic patients.

Spontaneous eye-blinking, a possible measure of central dopaminergic activity, was studied in 55 drug-free chronic schizophrenic patients subdivided by cerebral ventricular size. Blink rates were higher in schizophrenic patients than in normal control subjects, regardless of cerebral ventricle size. Neuroleptics lowered blink rates in patients with normal ventricles but did not affect blink rates in patients with large ventricles. Insofar as blinking is a dopaminergic parameter, these findings suggest that the dopamine hypothesis of schizophrenia is most relevant in patients with normal ventricles.

Adult↗
PubMed1984

Blink rates and disorders of movement.

Blink rate, a putative noninvasive marker of central dopamine activity, was assessed in medication-free patients with Parkinson's disease, progressive supranuclear palsy, Huntington's disease, and dystonia. The normal control rate of 24 blinks per minute was significantly higher than the rate of 12 and 4 blinks per minute recorded for patients with Parkinson's disease and progressive supranuclear palsy, respectively. The rates for patients with Huntington's disease and dystonia did not differ significantly from those of controls (36 and 26 blinks per minute, respectively).

Adult↗
PubMed1983

Spontaneous eye-blink rates and dopaminergic systems.

A series of studies demonstrated a possible relationship between eye-blink rate and central dopamine activity. First, apomorphine and other dopamine agonists acutely increased blink rate in monkeys, an effect blocked by sulpiride. Secondly, parkinsonian patients with levodopa-induced dyskinesia exhibited twice the mean blink rate (21 blinks/min) of other parkinsonians (11 blinks/min, P less than 0.002) whereas the more symptomatic of the nondyskinetic patients had a very slow rate (3 blinks/min, P less than 0.01). Thirdly, schizophrenic patients had an elevated mean blink (31 vs 23 blinks/min for normals, P less than 0.05) which was normalized by neuroleptic treatment. Thus, the correlation with central dopamine activity may also prove clinically useful in selected neuropsychiatric disorders.

Animals↗