Search PubMed⌕ Search

Biomedical subjects

C N Karson

Publications and source records attributed to C N Karson.

At least 19 recordsLinked to original sources
PubMed1992

Fluoxetine and trifluoperazine in human brain: a 19F-nuclear magnetic resonance spectroscopy study.

Fluorine-19 (19F) is a nonradioactive isotope that is well-suited to nuclear magnetic resonance spectroscopy (NMRS) and is a constituent of several medications used to treat psychiatric illnesses. Fluoxetine, a trifluorinated agent, generated a signal from brain that was readily measured by 19F-NMRS. Estimated brain concentrations ranged from 1.3-5.7 micrograms/ml in six subjects at a steady state dose of 40 mg/day. Enhanced sensitivity of 19F has been obtained by conforming the surface coil to the shape of the forehead. Hence, at the current state of development, 19F-NMRS can be applied to clinical questions relevant to concentrations of fluoxetine in brain. We also report observation of NMRS signals from fluorinated neuroleptics in a number of patients at steady state. These signals continue to be difficult to obtain, although a correlation between dose and estimated brain concentrations is suggested.

Adult↗
PubMed1992

Outcomes and costs of two VA inpatient treatment programs for older alcoholic patients.

One hundred thirty-seven older alcoholic patients were randomly assigned to two different inpatient treatment programs at a Veterans Affairs medical center and followed for one year after discharge. The older alcoholic rehabilitation (OAR) program was operated by a tolerant staff that specialized in treating elderly alcoholics. Treatment included reminiscence therapy with goals of developing patient self-esteem and peer relationships. The traditional care program emphasized confrontation to focus on patients' past failures and present conflicts. Patient care costs were slightly lower (2.5 percent lower) in the OAR program than in the more traditional program, and OAR patients were 2.1 times more likely to report abstinence at one year. Response to the OAR program was best for patients over 60 years of age.

Aged↗
PubMed1991

The brain stem reticular formation in schizophrenia.

Post-mortem brain tissue was obtained from four patients with schizophrenia and five controls to study cell groups in the brain stem reticular formation. Cholinergic neurons in the pedunculopontine nucleus (PPN) and lateral dorsal tegmental nucleus (LDT) were labeled using nicotinamide adenosine dinucleotide phosphate (NADPH)-diaphorase histochemistry, while catecholaminergic neurons of the locus ceruleus (LC) were labeled immunocytochemically using an antibody to tyrosine hydroxylase. In schizophrenic patients, there were increased numbers of neurons in the PPN labeled by NADPH-diaphorase and reduced cell size in the LC. These results implicate the reticular formation as a possible pathophysiological site for at least some patients with schizophrenia. This also suggests that some of the deficits observed may be based on faulty neurodevelopment.

Aged↗
PubMed1990

Blink rates in schizophrenia.

In schizophrenia, blink rates are frequently elevated and the peak of the electroencephalographic alpha rhythm is often absent or of a lower frequency. Emerging evidence suggests that both blinks and the alpha rhythm may be controlled by a linked neuroanatomical circuit that begins in rostral pons and involves several subcortical structures as well as the occipital cortex. Blink-alpha abnormalities in schizophrenia further suggest that this blink-alpha neurocircuit may be a locus of the pathophysiological process of this disorder.

Arousal↗
PubMed1990

Dyskinetic movements, cognitive impairment, and negative symptoms in elderly neuropsychiatric patients.

The presence or absence of tardive dyskinesia, cognitive status, and psychopathology were assessed in a group of elderly male psychiatric patients (N = 49) in a nursing home setting. Twenty-five patients were found to have tardive dyskinesia, which was associated with a greater degree of cognitive impairment and negative symptoms. This finding was not related to obvious macroscopic organic pathologies, which were less prevalent in the dyskinetic patients. In fact, patients with frontal lesions (primarily lobotomies) had a significantly lower prevalence of tardive dyskinesia.

Aged↗
PubMed1989

High prevalence of visual hallucinations in research subjects with chronic schizophrenia.

The authors examined the prevalence of visual hallucinations in severely ill hospitalized research subjects with carefully diagnosed chronic schizophrenia and found it to be high. A chart review of 100 discharged subjects revealed documentation of visual hallucinations in 32%, and a prospective examination of 43 additional subjects revealed a history of visual hallucinations in 56% (N = 24). Also, the fact that in 43% of the patients with visual hallucinations the history of visual hallucinations was first documented during the research ward work-up suggests that clinicians frequently do not inquire about visual hallucinations in patients with chronic schizophrenia.

Chronic Disease↗
PubMed1989

Blinking.

Spontaneous blink rates are controlled by a definable neural system originating in PPRF with facilitatory modulation from SN and superior colliculus and inhibitory modulation provided by cerebellum and occipital cortex. The thalamus may also be involved but the result of its influence is not clear. Reflex blinking is often reduced when spontaneous blink rate is increased and the reverse applies as well. The anatomic control of reflex is primarily in structures in the caudal half of pontine tegmentum and rostral midbrain. However, SN and cerebellum and other structures that regulate blink rate also modulate reflex blinking. Neurochemical control as determined by neuropharmacological experiments is exerted by dopaminergic, cholinergic and GABAergic systems of brain stem. Dopamine activity correlates directly with blink rate whereas agonism of the other two relevant neurotransmitter systems may inhibit blink rate. Clinical implications in central nervous system disease are currently restricted to Parkinson's disease, schizophrenia and autism. In the former illness, reduced blink rate signifies a worsening of the illness and a significant increase in blink rate in patients treated with dopamine agonist may be a harbinger of agonist-induced dyskinesia. In schizophrenia, increased blink rate, even in medication-naive subjects, may signify involvement of the structures that regulate blinking. This is important because these structures are rarely invoked as sites of potential pathophysiological import in schizophrenia. Similar considerations apply to autism except that increased blinking more clearly differentiates this disorder from other forms of retardation.

Animals↗
PubMed1988

Computerized EEG in schizophrenia.

Despite advances in the processing and display of electroencephalographic (EEG) data, the utility of this inexpensive and noninvasive technique in the investigation of schizophrenia has not been well established. We studied the resting EEG in 19 medication-free patients with chronic schizophrenia and 21 normal controls. Patients with schizophrenia had increased delta activity which was not specific to the frontal regions. Schizophrenic patients also had increased fast activity, and this increase was left sided for the fast beta frequency. Alpha frequency was reduced (less than 10.2 Hz) in 7 of 16 schizophrenic patients. Moreover, those patients with an alpha frequency reduction had a significantly larger mean cerebral ventricular size. These results indicate that the EEG does detect neurophysiological changes in schizophrenia. Our understanding of these changes may be enhanced by other neuroimaging techniques such as computed tomography.

Adult↗
PubMed1988

Cerebral structural pathology in schizophrenia: evidence for a selective prefrontal cortical defect.

To replicate earlier findings of central and cortical cerebral structural abnormalities and to further examine specific prefrontal cortical irregularities in schizophrenia, the authors examined computerized tomographic (CT) scans of 71 patients with chronic schizophrenia and 30 normal volunteer control subjects for ventricle-brain ratio (VBR), third ventricle width, and prominence of cortical markings in a generalized (parieto-occipital) distribution compared with the prefrontal area. Patients showed significantly larger VBRs and third ventricle widths than control subjects. Patients also showed significantly greater prefrontal markings in terms of both the number of individuals affected and the degree of difference. The relative differences on measures of VBR and prefrontal atrophy did not appear gender related, but the difference in third ventricle width between schizophrenic and control women was greater than that between schizophrenic and control men.

Adult↗
PubMed1988

Alpha frequency in schizophrenia: an association with enlarged cerebral ventricles.

Low alpha frequency (less than 10.2 Hz) occurred more frequently in medication-free schizophrenic patients than in normal control subjects, as determined by quantitative EEG analysis. Furthermore, those patients with low alpha frequency had significantly larger lateral ventricles, as measured by CT scan, than did other schizophrenic patients (mean +/- SD ventricle-brain ratios = 9.8 +/- 1.9 versus 5.0 +/- 2.4; p less than 0.01). This finding suggests the existence of a relationship between cerebral structural pathology and the alpha rhythm that may be based on involvement of alpha-generating structures which border the cerebral ventricles. Future EEG studies of schizophrenia may resolve these questions in the context of other brain findings.

Adult↗
PubMed1988

Physiology of normal and abnormal blinking.

Blink rate is determined by many factors, including local eye irritation, the state of the corneal tear film, factors related to general visual function, the amount of general facial movement, cognitive variables, and the level of arousal. These factors appear to be mediated by several neuroanatomic structures (Table 2). The timing and the nature of the interrelationship between neuroanatomic structures during blinking remains to be determined. Dopamine is the neurotransmitter that is most strongly linked to blinking, exerting its effect on blinking primarily through the D2 receptor. The reduced rate in Parkinson's disease seems to implicate the nigrostriatal system. Perhaps efferents of the nigrostriatal system, such as those to the superior colliculus, are primarily involved, as suggested by the reduced blinking in PSP. Changes in blinking produced in the sylvian aqueduct syndrome further suggest involvement of the periaqueductal structures. At best, however, these conclusions are tentative, as the biochemical neuroanatomy will probably prove more complicated than suggested by the initial studies using the dopaminergic paradigm. Nevertheless, insofar as blink rate represents a noninvasive probe of CNS dopamine activity, the failure to associate dyskinesias (except levodopa-induced dyskinesia) with increased blinking, indicates that the pathophysiology of these conditions may not involve hyperactivity of CNS dopamine systems. Fittingly, the current clinical potential of blink rate seems maximal in parkinsonism, both to follow the severity of the illness and to monitor side effects of dopamine agonist treatment.

Animals↗
PubMed1987

Computed electroencephalographic activity mapping in schizophrenia. The resting state reconsidered.

Several topographic mapping studies of electroencephalographic (EEG) power spectra have reported increased slow (delta) activity in the frontal regions of schizophrenic patients. Using supraorbital and lateral canthus electrodes to detect eye movement, we deleted EEG epochs during eye movement in 15 medication-free patients with schizophrenia and in 13 normal control subjects. Power spectral analysis of the 28-channel EEG demonstrated a diffuse mild increase in delta activity in schizophrenic patients compared with normal control subjects but no tendency for frontal localization of this slow activity. There were no differences between schizophrenic patients and normal control subjects in other frequency bands. These results, which replicate earlier findings of increased delta activity in schizophrenia, emphasize the importance of excluding the slow activity due to eye movement in the comparisons of summed EEG spectra. This emphasis can best be ensured by equating the summed spectra from extraocular movement channels of experimental and control groups.

Adult↗
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↗