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Biomedical subjects

B K Toone

Publications and source records attributed to B K Toone.

At least 37 records · Page 2Linked to original sources
PubMed1993

Neural correlates of planning ability: frontal lobe activation during the Tower of London test.

Single-photon emission computerised tomography (SPECT) was used to investigate whether pre-frontal cerebral blood flow in normal adults is increased during planning activity. A subtraction technique was used in which regional cerebral blood flow (rCBF) was measured in subjects during a computerised version of the Tower of London task. Both rCBF and performance on this task were compared to a motor control condition requiring the same responses and using the same visual display. The level of rCBF was significantly increased in the left pre-frontal cortex during the Tower of London task. In addition, subjects who took more time planning their moves, and less moves to complete a problem had a significantly higher level of rCBF in the left pre-frontal cortex. Subsequent execution latencies for the task were correlated negatively with both left and right rCBF.

Adult↗
PubMed1993

Premorbid social underachievement in schizophrenia. Results from the Camberwell Collaborative Psychosis Study.

In an investigation of the timing and precursors of social decline in schizophrenia and affective psychosis, 195 subjects from the Camberwell Collaborative Psychosis Study were currently of lower social class than were their fathers. A comparison between father's occupation and proband's best premorbid occupational level indicated underachievement confined to DSM-III schizophrenia, there being no such effect in affective psychosis. Decline in social status following onset of psychosis, analysed by comparing best premorbid occupation with current occupation, was marked in both schizophrenia and affective psychosis, indicating a non-specific effect. Schizophrenic patients who failed to achieve their fathers' social status had poorer educational qualifications than those who equalled or bettered their paternal social class, despite similar premorbid IQ (NART) scores and age at onset of psychosis. These results indicate that schizophrenia may be manifest before the onset of psychosis, and lend weight to the notion of a developmental origin to this disorder.

Adolescent↗
PubMed1992

A controlled study of 99mTc-HMPAO single-photon emission imaging in chronic schizophrenia.

Regional cerebral blood flow (rCBF) during a word fluency task was compared in twenty-five male, right-handed, medicated schizophrenic patients and twenty-five age-matched male, right-handed healthy volunteers, using 99mtechnetium-HMPAO multidetector single-photon emission tomography. Increased rCBF in caudate and thalamus was found in patients, probably secondary to neuroleptic medication. Patients showed decreased rCBF in left frontal cortical regions and increased rCBF in left posterior cortical regions, compared to controls. Patterns of left-sided frontal rCBF dominance in controls were reversed in patients, as were normal patterns of right-sided parietal rCBF dominance. Negative symptom score correlated inversely with mesial frontal rCBF, particularly on the left.

Adult↗
PubMed1992

Folate deficiency, biopterin and monoamine metabolism in depression.

Seven (21%) of 34 patients with a severe DSM-III diagnosis of major depression had red-cell folate levels below 150 ng/ml. This subgroup with folate deficiency had significantly lower CSF 5-hydroxyindoleacetic acid (5HIAA) compared to neurological controls. For all depressed patients red-cell folate was significantly correlated with CSF 5HIAA and homovanillic acid (HVA). CSF tetrahydrobiopterin (BH4) was significantly correlated with CSF 5HIAA and HVA and red-cell folate. Our observations provide further evidence of the links between folate, biopterin and monoamine metabolism in depression.

Adult↗
PubMed1992

Quantification of regional cerebral blood flow (rCBF) using 99Tcm-HMPAO and SPECT: choice of the reference region.

The effects of the choice of the reference region in determining the relative regional cerebral blood flow (rCBF) using 99Tcm-hexamethylpropylene amine oxime (HMPAO) single photon emission tomography (SPECT) have been studied in order to establish or exclude it as a cause of inconsistencies in these studies. Relative rCBF was estimated by normalizing the regional count densities to two reference regions, the cerebellum and the whole slice, in 35 patients with Alzheimer's disease (AD), 25 patients with chronic schizophrenia (SCH) and the same number of matched normal volunteers. The statistical significance of the differences in rCBF between patients and their matched normals varied in the two sets of rCBF data. Smaller differences were highly significant while some larger differences were of less significance with whole slice normalization. The results suggest that the choice of reference region is one of the causes resulting in discrepancies in the results from various centres. The need to use a standard reference region is indicated.

Alzheimer Disease↗
PubMed1992

What does rCBF-SPECT offer in schizophrenia?

Schizophrenia is a major psychiatric problem common in the younger population. Structural imaging and findings on autopsy have not yet revealed a specific deficit in these patients. Uncertainty in clinical diagnosis based on a set of signs and symptoms is another drawback in the management of this patient population. Regional cerebral blood flow studies (rCBF) using single photon emission computed tomography (SPECT) offers the opportunity to study the underlying phenomenon and to detect the specific functional deficits in schizophrenia.

Amphetamines↗
PubMed1992

Ventricular size and regional cerebral blood flow in schizophrenia: an attempted replication.

We attempted to replicate the finding of Berman et al. (1987) that frontal cortical blood flow correlated inversely with ventricular size in schizophrenia. Computed tomography and high-resolution 99m-Tc-HMPAO single photon emission computed tomography were performed in 25 right-handed chronic schizophrenic men engaged in a word-fluency task. Weak, nonstatistically significant inverse correlations were found between the ventricle-brain ratio (VBR) and frontal cortical blood flow. The VBR was significantly inversely correlated with the ratio of left to right medial frontal blood flow.

Adult↗
PubMed1991

Primary progressive non-fluent aphasia: a case study.

A case study of a 65 year old man is described with an eight-year history of progressive primary non-fluent aphasia accompanied by agrammatism, phonemic paraphasias and mild spelling dysgraphia. His naming ability, however, has remained at an exceptionally high level and there has been no evidence of impairment of word or sentence comprehension. Non-verbal skills and memory functions have also been preserved within the range of his very high premorbid level of abilities. Single photon emission computed tomography was consistent with bifrontal hypoperfusion. We argue that the selective language deficits in this patient are characteristic of dynamic aphasia and of other speech disturbances which are also known to be associated with left frontal lesions. The possible underlying pathology is discussed in the context of known degenerative disorders.

Agnosia↗
PubMed1991

Metabolic clearance rate of testosterone in male epileptic patients on anti-convulsant therapy.

There are several reports which state that male epileptics on anti-convulsant therapy have reduced sexual activity. We and others have shown that, although total testosterone is raised, the free testosterone concentration is reduced in this patient population. This could be a result of an increased metabolic clearance rate (MCR) of testosterone, inadequate secretion of LH to stimulate testosterone synthesis or inappropriately low testosterone production by the Leydig cells. We have examined these possibilities by measuring the MCR of testosterone in 15 male epileptics on anti-convulsant therapy. In this group of patients, the mean LH (9.3 +/- 5.9 IU/l) and sex-hormone binding globulin (SHBG) (54.5 +/- 22.9 nmol/l) concentrations were significantly greater than those of five normal control subjects (4.7 +/- 1.11 IU/l and 26.0 +/- 7.0 nmol/l respectively). Mean total testosterone concentrations of the two groups were not significantly different but the mean percentage of free testosterone and free testosterone concentration were significantly lower in the patient population (2.06 +/- 0.43 vs 2.98 +/- 0.27 and 0.56 +/- 1.1 vs 0.79 +/- 0.07 pmol/l). The MCR of testosterone was significantly lower in the patients (773 +/- 322 vs 1354 +/- 443 l/day) and showed a positive correlation with the percentage of free testosterone. Therefore, our results suggest that the lowered free testosterone in male epileptics on anti-convulsant therapy is not due to an increased MCR of testosterone. The increased LH concentration suggests primary hypogonadism. This, in turn, could be responsible for low free testosterone levels in the presence of normal testosterone.

Adult↗
PubMed1990

Enhancement of recovery from psychiatric illness by methylfolate.

41 (33%) of 123 patients with acute psychiatric disorders (DSM III diagnosis of major depression or schizophrenia) had borderline or definite folate deficiency (red-cell folate below 200 micrograms/l) and took part in a double-blind, placebo-controlled trial of methylfolate, 15 mg daily, for 6 months in addition to standard psychotropic treatment. Among both depressed and schizophrenic patients methylfolate significantly improved clinical and social recovery. The differences in outcome scores between methylfolate and placebo groups became greater with time. These findings add to the evidence implicating disturbances of methylation in the nervous system in the biology of some forms of mental illness.

Adult↗
PubMed1990

The ventricle-brain ratio (VBR) in functional psychoses: an admixture analysis.

An admixture analysis of the ventricle-brain ratio (VBR) on the computed tomographic (CT) scans of 72 patients with functional psychosis and 50 healthy controls was made, to determine whether two distinct distributions could be demonstrated. The patients showed a more positively skewed distribution, and a significantly higher mean VBR, but there was no evidence of more than one underlying normal distribution of values. The use of VBR alone to define a biologically separate subgroup of patients is not supported.

Adolescent↗
PubMed1990

The ventricular-brain ratio (VBR) in functional psychoses: the relationship of lateral ventricular and total intracranial area.

CT scans were performed on 72 consecutive patients with a functional psychosis, and compared with 50 community controls. There was a specific difference in lateral ventricular area between these two groups but it accounted for only 11% of the variance in this measure. In contrast, racial and sexual differences in the ventricular-brain ratio (VBR) related to differences in intracranial area. It is argued that analysis of variance, using lateral ventricular area and intra-cranial area, is more informative than VBR in examining these structural changes in functional psychoses.

Adolescent↗
PubMed1990

Cerebrospinal fluid S-adenosylmethionine in depression and dementia: effects of treatment with parenteral and oral S-adenosylmethionine.

Cerebrospinal fluid (CSF) S-adenosylmethionine (SAM) levels were significantly lower in severely depressed patients than in a neurological control group. The administration of SAM either intravenously or orally is associated with a significant rise of CSF SAM, indicating that it crosses the blood-brain barrier in humans. These observations provide a rational basis for the antidepressant effect of SAM, which has been confirmed in several countries. CSF SAM levels were low in a group of patients with Alzheimer's dementia suggesting a possible disturbance of methylation in such patients and the need for trials of SAM treatment.

Administration, Oral↗
PubMed1990

The functional psychoses in Afro-Caribbeans.

When 54 Afro-Caribbean and 49 white British consecutive psychotic in-patients were prospectively studied for clinical differences in course of illness and pattern of symptoms, no major differences were found. This does not support the hypothesis that misdiagnosis within the psychoses can explain the higher admission rates of schizophrenia calculated for Afro-Caribbean populations.

Acculturation↗
PubMed1989

Hyposexuality and epilepsy: a community survey of hormonal and behavioural changes in male epileptics.

A survey of five group practices in South London identified 60 male patients currently undergoing treatment for epilepsy. Fifty-four agreed to participate in a detailed enquiry into aspects of their sexual activity and behaviour. Anterior pituitary and sex-hormone levels were measured. The epileptic patients were characterized by low levels of sexual activity and interest. Temporal-lobe and non-temporal-lobe epileptics were indistinguishable in these respects, but when the latter group was further subdivided into primary generalized epilepsy and focal non-temporal lobe epilepsy, the focal groups (both temporal lobe and non-temporal lobe) were more impaired. Hormonal analysis confirmed earlier hospital-clinic-based reports. In the epilepsy group, plasma free testosterone and percentage free testosterone values were decreased, sex hormone binding globulin, luteinizing hormone (LH) and follicle stimulating hormone (FSH) were increased compared to values in a normal healthy population. As association between the behavioural and hormonal indices of hyposexuality was shown, particularly for LH, but this was less apparent than in previous work.

Adolescent↗