Biomedical subjects
S A Spence
Publications and source records attributed to S A Spence.
Discrete neurophysiological correlates in prefrontal cortex during hysterical and feigned disorder of movement.
The clinical distinction between hysterical symptoms and those that are feigned awaits objective validation. We used functional neuroimaging to examine the neural correlates of these two disorders.
Functional anatomy of verbal fluency in people with schizophrenia and those at genetic risk. Focal dysfunction and distributed disconnectivity reappraised.
BACKGROUND: PET studies of verbal fluency in schizophrenia report a failure of 'deactivation' of left superior temporal gyrus (STG) in the presence of activation of left dorsolateral prefrontal cortex (DLPFC), which deficit has been attributed to underlying 'functional disconnectivity'. AIM: To test whether these findings provide trait-markers for schizophrenia. METHOD: We used H2(15)O PET to examine verbal fluency in 10 obligate carriers of the predisposition to schizophrenia, 10 stable patients and 10 normal controls. RESULTS: We found no evidence of a failure of left STG deactivation in carriers or patients. Instead, patients failed to deactivate the precuneus relative to other groups. We found no differences in functional connectivity between left DLPFC and left STG but patients exhibited significant disconnectivity between left DLPFC and anterior cingulate cortex. CONCLUSIONS: Failure of left STG 'deactivation' and left fronto-temporal disconnectivity are not consistent findings in schizophrenia; neither are they trait-markers for genetic risk. Prefrontal functional disconnectivity here may characterise the schizophrenic phenotype.
More stringent threshold needed.
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No evidence for left superior temporal dysfunction in asymptomatic schizophrenia and bipolar disorder. PET study of verbal fluency.
BACKGROUND: Positron emission tomography (PET) studies have revealed functional left superior temporal gyrus (STG) abnormalities in symptomatic schizophrenia during word generation. AIMS: To discover if this dysfunction is present in asymptomatic schizophrenia. To determine whether, without concurrent symptomatology, schizophrenia and bipolar affective disorder (BPD) are distinguishable by differing regional cerebral blood flow (rCBF) patterns during word generation. METHOD: A PET verbal fluency protocol was applied to six patients with BPD in remission and six patients with asymptomatic schizophrenia. Analysis included 10 control subjects from a contemporaneous study. RESULTS: All groups showed relative reduction of rCBF in both superior temporal cortices. There were no quantitative differences in any group comparison. All groups exhibited negative covariation between rCBF in left prefrontal and right (but not left) temporal regions. CONCLUSIONS: Abnormal patterns of left STG function cannot be regarded as a trait marker for schizophrenia. Functional abnormalities may reflect aspects of mental state.
Rate of decline of chlorfluazuron concentration in the fat of cattle.
OBJECTIVE: To determine the rate of decline of chlorfluazuron (CFZ) concentration in the fat of cattle. DESIGN: A field depletion study. ANIMALS: Fifteen steers that had become contaminated with CFZ through eating cotton trash or cotton leaf pellets derived from CFZ-treated cotton crops. PROCEDURE: Fat samples were collected from the cattle at about 3 week intervals according to a schedule where each animal was sampled on four occasions up to 340 days after removal from the contaminated feed source. RESULTS: When the effects of dilution are removed CFZ concentrations were found to decline slowly for about 200 days. Depletion was minimal between 200 and 340 days. CONCLUSION: According to this trial, CFZ-contaminated, nonlactating cattle which have finished growing will remain contaminated. Field experience has not supported this conclusion.
Prefrontal cortex activity in people with schizophrenia and control subjects. Evidence from positron emission tomography for remission of 'hypofrontality' with recovery from acute schizophrenia.
BACKGROUND: Hypo-activation of the left dorsolateral prefrontal cortex is inconsistently found in neuroimaging studies of schizophrenia. As the left dorsolateral prefrontal cortex is involved in the generation of action, disordered function in this region may be implicated in schizophrenic symptomatology. METHOD: We used H2 15O positron emission tomography to study dorsolateral prefrontal cortical function in men with schizophrenia (n = 13) and male control subjects (n = 6) performing joystick movements on two occasions, 4-6 weeks apart. The patients were initially in relapse. To clarify dorsolateral prefrontal cortical function we also scanned another group of control subjects (n = 5) performing mouth movements. RESULTS: The control subjects performing hand or mouth movements activated the left dorsolateral prefrontal cortex to a maximum when the movements were self-selected. The men with relapsed schizophrenia exhibited left dorsolateral prefrontal cortical hypoactivation, which remitted with symptomatic improvement. CONCLUSIONS: Hypofrontality in these patients is a dynamic phenomenon across time, possibly related to current symptomatology. The most appropriate question about the presence of hypofrontality in schizophrenia may be when, rather than whether, it will occur.
Are first-rank symptoms encryption errors.
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Pathophysiology of 'positive' thought disorder in schizophrenia.
BACKGROUND: Formal thought disorder is a characteristic feature of psychosis, but little is known of its pathophysiology. We have investigated this in schizophrenia using positron emission tomography (PET). METHOD: Regional cerebral blood flow was measured using H2(15)O and PET while six people with schizophrenia were describing a series of 12 ambiguous pictures which elicited different degrees of thought-disordered speech. In a within-subject design, the severity of 'positive' thought disorder was correlated with cerebral blood flow across the 12 scans in each subject. RESULTS: Verbal disorganisation (positive thought disorder) was inversely correlated with activity in the inferior frontal, cingulate and left superior temporal cortex, and positively correlated with activity in the parahippocampal/anterior fusiform region bilaterally, and in the body of the right caudate (P < 0.001). The total amount of speech produced (independent of thought disorder) was positively correlated with activity in the left inferior frontal and left superior temporal cortex. CONCLUSIONS: The severity of positive thought disorder was inversely correlated with activity in areas implicated in the regulation and monitoring of speech production. Reduced activity in these regions may contribute to the articulation of the linguistic anomalies that characterise positive thought disorder. The positive correlations between positive thought disorder and parahippocampal/anterior fusiform activity may reflect this region's role in the processing of linguistic anomalies.
A PET study of voluntary movement in schizophrenic patients experiencing passivity phenomena (delusions of alien control).
Schizophrenic patients experiencing passivity phenomena believe their thoughts and actions to be those of external, or alien, entities. We wished to test the hypothesis that voluntary motor action in such patients would be associated with aberrant patterns of activation within the cerebral motor system. We used H2(15)O PET to study patients while they performed paced joystick movements on two occasions 4-6 weeks apart. During the first scan passivity symptoms were maximal, while by the second scan these symptoms had significantly improved in five of the seven patients. Two control groups were also scanned on two occasions: deluded schizophrenic patients without passivity phenomena and normal subjects. In normal subjects, performance of freely selected joystick movements with the right hand, compared with rest, revealed relative activation of prefrontal, premotor, motor and parietal cortical regions. Schizophrenic patients with passivity showed hyperactivation of parietal and cingulate cortices. This hyperactivation remitted in those subjects in whom passivity decreased over time. This reversible hyperactivity was not a feature of schizophrenics without passivity. Given that these hyperactive cerebral regions subserve attention to internal and external bodily space, and the attribution of significance to sensory information, they provide a plausible anatomical substrate for the misattribution of internally generated acts to external entities: the cardinal feature of delusions of passivity (alien control).
Responses in milk production to control of gastrointestinal nematode and paramphistome parasites in dairy cattle.
OBJECTIVE: To determine the effect of treating naturally acquired gastrointestinal nematode and paramphistome infections on milk production in dairy cattle. DESIGN: A field trial. ANIMALS: One thousand two hundred and thirty nine dairy cows. PROCEDURE: Cows were either not treated or treated with 4.5 mg/kg oxfendazole, 16.6 mg/kg oxyclozanide or 4.5 mg/kg oxfendazole and 16.6 mg/kg oxyclozanide in March, May and August. RESULTS: A significant increase in milk production, averaging 0.4 L (SE 0.2) per day, was seen when dairy cows infected with gastrointestinal nematodes and paramphistomes were treated with oxfendazole or oxfendazole and oxyclozanide in March, May and August. Cows treated with oxyclozanide alone at these times produced no more milk than untreated cows. Faecal egg counts confirmed that oxyclozanide treatment reduced paramphistome populations and oxfendazole treatment reduced nematode populations in cows over the 7-month monitoring period. CONCLUSION: When dairy cows infested with gastrointestinal nematodes and paramphistomes were treated with oxfendazole alone or oxfendazole and oxyclozanide in March, May and August milk production increased.
Personality disorder and police section 136 in Westminster: a retrospective analysis of 65 assessments over six months.
Section 136 of the 1983 Mental Health Act empowers the police to detain those suspected of being mentally ill in public places. The current study is a retrospective analysis of those occurring within Westminster, London, over a six-month period. A high rate of referral was found. In those individuals assessed, schizophrenia was the commonest diagnosis, but personality disorder provided the largest number of assessments. This was due to the propensity of the latter individuals to present on multiple occasions. Those with personality disorders were significantly less likely to be placed under further sections of the Mental Health Act, less likely to be admitted to hospital and more likely to re-present under a further section 136. The inability of the current system to address these individuals' needs is a cause for concern.
Depressive disorder due to craniopharyngioma.
Secondary causes of depression are legion, and must always be considered in patients presenting with features atypical of primary idiopathic depressive disorder. The case described is that of a middle-aged woman presenting initially with a major depressive disorder who was subsequently found to have a craniopharyngioma, leading to a revised diagnosis of mood disorder due to the tumour. Some features of the presentation might have led to earlier diagnosis had their localizing significance been recognized. Diencephalic lesions should always be considered in patients presenting with the hypersomnic-hyperphagic variant of depressive disorder.
Exploring the relationship between purpose in life and African American adolescents' use of prenatal care services.
This article presents findings of a study that explored the relationship between purpose in life and African American adolescents' use of prenatal care services. The findings revealed no statistically significant relationship, thus suggesting that purpose in life may not be a crucial factor in determining whether African American adolescents use prenatal care services. The need to explore the influence of other variables on service use and the importance of considering such findings for appropriate health care and social work intervention are discussed.
Antimicrobial use and residues in calves in northern New South Wales.
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The rate of decline of alpha- and beta-benzene hexachloride residues in contaminated pigs.
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