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Biomedical subjects

I Harvey

Publications and source records attributed to I Harvey.

At least 109 records · Page 6Linked to original sources
PubMed1995

Against the laterality index as a measure of cerebral asymmetry.

The laterality index (right - left)/(right + left) has been widely used to measure cerebral asymmetry. However, its validity rests on the assumption that confounding effects of overall head and body size are symmetrical on both sides of the brain. We have found that this assumption may not always be justified. In magnetic resonance imaging data from a group of 43 right-handed normal control and schizophrenic subjects, the laterality index controlled poorly for the asymmetrical confounding effect of height, leading to a spurious (although statistically significant) correlation between height and apparent cerebral asymmetry. Regression modeling is advocated as a more rational and effective way to explore and control size effects confounding cerebral lateralization.

Adult↗
PubMed1995

X-ray absorption studies and homology modeling define the structural features that specify the nature of the copper site in rusticyanin.

Rusticyanin, a blue copper protein, possessing the highest redox potential among this class of proteins and a high stability at acidic pH reveals homology with the C-terminal end of the other single copper containing blue proteins and an interesting homology to parts of the blue copper domain of the multi-copper proteins such as the nitrite reductases. Extended X-ray absorption fine structure (EXAFS) data at pH 2.0 reveal that Cu is ligated to two His and a Cys in the inner coordination sphere, similar to other blue copper centers. Modeling studies suggest that His85 is the ligating histidine from the N-terminal end. Its neighboring residue is a serine rather than the asparagine found in all known blue Cu proteins. The high stability of the copper site may arise in part due to this substitution. The Cu binding site is surrounded by aromatic residues which may provide further protection for the metal in an acidic environment. In addition, the high number of solvent-exposed uncompensated lysine residues is likely to be of functional relevance under low pH conditions. EXAFS data show a very small change (relative to azurin) in the copper site upon reduction, consistent with a more constrained copper center in rusticyanin compared to azurin and a higher redox potential.

Absorptiometry, Photon↗
PubMed1995

Behavioural effects of norpethidine, a metabolite of pethidine, in rats.

This study investigated behavioural effects of the toxic pethidine metabolite, norpethidine, in rats and its interactions with reserpine, apomorphine and physostigmine. Following intraperitoneal administration, brain concentrations of norpethidine reached a plateau after 20-40 min and remained elevated for 2 h. In the dose range 0.06-0.18 mmol/kg, norpethidine induced myoclonic jerks, a characteristic splayed posture, and episodes of exaggerated shivering. Forward locomotion, grooming, yawning and rearing were suppressed. Seizures and reverse locomotion occurred occasionally. Administration of reserpine 1 h prior to norpethidine, or of apomorphine or physostigmine 15 min after norpethidine, did not alter the norpethidine-induced behaviours; neither did norpethidine block the effects of apomorphine or physostigmine. The characteristic profile of behaviours induced by norpethidine make this toxicant readily amenable to animal studies. Our results indicate that its mechanism of action is unlikely to involve dopaminergic or cholinergic pathways.

Animals↗
PubMed1995

Morbid risk of schizophrenia for relatives of patients with cannabis-associated psychosis.

Twenty-three patients admitted with acute psychosis who were cannabis positive on urinary screening were each matched, with respect to sex, with two psychotic controls who screened negatively for all substances. The lifetime morbid risk of psychiatric disorder was estimated among the first degree relatives of cases and controls, using RDC-FH criteria to define diagnoses, and Weinberg's shorter method of age correction. The cases had a significantly greater familial morbid risk of schizophrenia (7.1%) than the controls (0.7%), while the risks of other psychoses, and of non-psychotic conditions were similar. The same pattern of familial risk was evident when the analysis was restricted to patients with DSM-III schizophrenia. The data suggest that the development or recurrence of acute psychosis in the context of cannabis use may be associated with a genetic predisposition to schizophrenia.

Adult↗
PubMed1995

Minor physical anomalies in psychoses: associations with clinical and putative aetiological variables.

This study of patients with functional psychoses set out to examine associations between minor physical anomalies (MPAs) and demographic, clinical, CT scan measures, and putative aetiological variables. 157 psychotic patients had minor physical anomalies assessed using a modified Waldrop scale. RDC diagnoses for these patients were: schizophrenia (n = 79), schizoaffective disorder (n = 31), mania (n = 24), major depression (n = 13), unspecified functional psychosis (n = 8), other organic psychosis (n = 2). 63 healthy white controls were also assessed with the modified Waldrop scale. Minor physical anomalies were not associated with any particular diagnosis. For white subjects, patients had significantly more MPAs than well controls. Anomalies of the palate were the most frequent item reported in patients and controls. For males, there was a weak association between the presence of MPAs and positive family history of a major psychiatric disorder. Those with MPAs required more frequent and longer psychiatric admissions, and showed impaired ability on a test sensitive to left parietal system function. Within the patient group, there were no associations between MPAs and gender, age at onset, negative symptoms, premorbid level of functioning, estimated premorbid intelligence, pregnancy and birth complications, and selected CT variables. Minor physical anomalies are found in a range of functional psychoses. There may be overlap between the various genes that predispose to psychiatric illness (especially in males) and those genes that predispose to developmental instability.

Adult↗
PubMed1995

Cerebral hemispheric asymmetry revisited: effects of handedness, gender and schizophrenia measured by radius of gyration in magnetic resonance images.

Abnormal patterns of cerebral hemispheric asymmetry have been inconsistently reported in association with schizophrenia. Radius of gyration (Rg) is a measure of the mean dispersion of points in a radially organized structure about that structure's centre of gravity. We developed computerized methods for estimating Rg of the magnetic resonance image (MRI) boundary between cortex and subcortex, and applied these methods to measurement of cerebral hemispheric asymmetry in 37 schizophrenics (SZs) and 30 controls (CONs). In right-handed CONs, Rg of right brain boundaries was significantly greater than Rg of left brain boundaries; in left-handed CONs, Rg of left brain boundaries was significantly greater than Rg of right brain boundaries. In right-handed males (both SZ and CON) there were significant differences in Rg between hemispheres; whereas in females (both SZ and CON), there were no such differences. Right-handed male SZs (N = 26) were distinguished by reversal of the right-handed male CON pattern of interhemispheric difference in Rg, and by global reduction in Rg of right brain boundaries. These was no evidence for significant abnormality of Rg in right-handed female SZs (N = 7). There findings suggest an important interactive effect of gender and schizophrenia on lateralized cerebral structure.

Adult↗
PubMed1995

The invasive management of angina: issues for consumers and commissioners.

OBJECTIVE: To review, from the purchaser's perspective, the current state of knowledge of techniques for investigation and treating coronary artery disease. The study was based on evidence from past and continuing randomised controlled trials (RCTs). CRITERIA FOR INCLUSION OF REPORTS: Articles listed on Medline (1990-3) with the keywords coronary disease, angina, and unstable angina (combined with surgery, economics, therapy, or drug therapy) and percutaneous transluminal coronary angioplasty (PTCA) and coronary artery bypass grafting (CABG) were included. Articles published before 1990 were obtained from two comprehensive literature reviews published by the Rand organisation in 1991 and from the papers obtained using the Medline search. A hand search of relevant journals published between July 1993 and June 1994 was also undertaken. Results from more recently published RCTs are included. RESULTS: CABG provides improved angina relief compared with drug treatment and may prolong life in patients with more severe illness. PTCA is also better than drug treatment, but less so than CABG, and its cost advantages over CABG decrease with time. Repeat intervention for return of symptoms is more frequently required after PTCA, but increasing numbers of patients are also undergoing second and third repeat CABG for graft occlusion in the years after the original operation. Newer PTCA techniques are not, as yet, fully evaluated. One technique, atherectomy, has been shown to be no more effective, and more expensive, than conventional balloon angioplasty. In the short term intracoronary stents reduce the problems associated with vessel occlusion after PTCA and therefore reduce the need for further intervention. PTCA should not be performed without ready access to cardiothoracic support. There is an increasing trend towards the development of coronary catheterisation units at peripheral sites. This may lead to increasing, inappropriate use of this investigation in suboptimal circumstances. CONCLUSIONS: Ischaemic heart disease is an important cause of morbidity and mortality and invasive management techniques are developing rapidly; some service expansion is occurring without trial evidence. More research is required to determine the optimum balance of PTCA, CABG, and angiography and population requirements for these procedures. In the meantime, in the absence of firm long term evidence of the superior cost effectiveness of PTCA compared with CABG, the rapid expansion of this procedure should be limited. Patients should be fully informed of the benefits and disadvantages of CABG and PTCA, where either procedure is indicated, to enable them to make fully informed choices.

Angioplasty, Balloon, Coronary↗
PubMed1995

Increased intracerebral cerebrospinal fluid spaces predict unemployment and negative symptoms in psychotic illness. A prospective study.

BACKGROUND: It has been suggested that the dimensions of cerebral ventricles are a risk factor for poor outcome in psychotic illness. METHOD: A cohort of 140 patients with functional psychoses of recent onset who had undergone CT scanning, were followed up for an average of 46 months and assessed on six dimensions of course and outcome of illness. RESULTS: Left and right sylvian fissure volumes and, to a lesser extent, third ventricular volume predicted negative symptoms and unemployment over the course of follow-up, the latter association being mediated by poor cognitive functioning. There was significant linear trend in risk over the distribution of sylvian fissure volumes in the cohort, and associations were especially evident in schizophrenic patients. No associations were found with global severity of illness, duration of hospital stay, homelessness, or affective symptoms. CONCLUSIONS: These findings support the notion that dimensions of the cerebral ventricles are a continuous risk factor for some measures of outcome in the functional psychoses.

Arousal↗
PubMed1995

Insight and psychotic illness. Cross-sectional and longitudinal associations.

BACKGROUND: Insight has recently re-emerged as an important aspect of psychopathology amenable to empirical study. We sought to examine the relationship between various aspects of insight into illness and clinical, sociodemographic and neuropsychological variables. METHOD: From an inner-London catchment area population, 150 in-patients with recent onset of psychosis were assessed on a variety of measures, including the Present State Examination (PSE). Subjects were followed up for a mean of four years and reassessed. RESULTS: High IQ was associated with better insight as rated on the PSE, while gender, ethnicity and a diagnosis of schizophrenia appeared to be unrelated. At follow-up, similar associations were found, as well as correlations with attitudes to treatment and a more elaborate measure of insight. Cerebral ventricular enlargement and tests of frontal lobe function did not correlate with insight, but there was a curious, strong association with left-handedness at both assessment points. Initial insight correlated significantly but weakly with insight at follow-up. CONCLUSIONS: The assessment of insight in psychosis has concurrent validity and is a distinct aspect of psychotic phenomenology. It may, in part, have a neuropsychological basis.

Adolescent↗
PubMed1994

Cannabis and acute psychosis.

The Present State Examination was used to assess the psychopathology of 23 psychotic patients who were cannabis positive on urinary screening, and 46 matched drug-free controls. Cases and controls were indistinguishable in terms of psychopathology, DSMIII diagnoses, onset of recent illness, the proportion of first admissions, ethnicity, and socio-economic class, differing only in their histories of substance use. These data suggest that psychosis which develops or recurs in the context of cannabis use does not have a characteristic psychopathology or mode of onset, and is not restricted to a particular ethnic or socio-demographic group. There is thus little evidence to support the validity of 'cannabis psychosis' as a diagnostic entity.

Acute Disease↗
PubMed1994

Volumetric MRI measurements in bipolars compared with schizophrenics and healthy controls.

Twenty-six patients with RDC bipolar disorder were compared with a previously reported group of 48 RDC schizophrenics and 34 healthy controls, using volumetric MRI measurements of cerebral, cortical and sulcal volumes. The bipolar group appeared no different from the controls, and both of these groups had significantly larger cerebral and cortical volumes than the schizophrenics. Our previous report of a significantly reduced cortical volume in the schizophrenic group, with a corresponding increase in the volume of sulcal fluid is, therefore, not a generalized feature of psychotic illness but may be more specific to schizophrenia.

Adult↗
PubMed1994

Fractal analysis of the boundary between white matter and cerebral cortex in magnetic resonance images: a controlled study of schizophrenic and manic-depressive patients.

This paper reports development of a computerized ('box-counting') method for estimation of fractal dimension (FD) of the magnetic resonance image (MRI) boundary between cerebral cortex and white matter; and the application of this method to MRIs of 39 schizophrenics (SZs), 23 manic-depressives (MDs) and 31 controls (CONs). Mean FD across all diagnostic groups was 1.402; 95% confidence interval (CI) 1.399 to 1.406. Mean FD was greater in boundaries extracted from manic-depressive patients than in boundaries extracted from controls (difference between MD and CON mean FDs = 0.008; 95% CI -0.002 to +0.018); and less in schizophrenics than in controls (difference between SZ and CON mean FDs = -0.003; 95% CI -0.011 to +0.005). Mean FD was positively correlated with subcortical volume and anterior cerebral volume, and negatively correlated with sulcal cerebrospinal fluid volume. Significant differences in mean FD between diagnostic groups were demonstrated by analysis of covariance (ANCOVA; P < 0.01), with age and volumetric measures of brain size as covariates; and manic-depressive boundaries were shown to have significantly greater values for residual FD (after controlling for effects of brain size) than boundaries extracted from controls (t test; P < 0.05). It is proposed that FD is a useful measure of clinically relevant differences in the complexity of MRI boundaries.

Adult↗
PubMed1994

Cerebral ventricle dimensions as risk factors for schizophrenia and affective psychosis: an epidemiological approach to analysis.

A case-control study was undertaken of volumetric computerized tomographic scan measures in 216 consecutive admissions for functional psychosis and 67 healthy community controls. Odds ratio analysis demonstrated significant linear trends in the association between increasing lateral and third ventricle volumes, and both RDC schizophrenia (N = 121) and schizo-affective disorder (N = 41); cases were consistently associated with larger volumes than controls. There was an association between larger third, but not lateral, ventricle size in affective psychoses (N = 54). These associations were statistically independent of intracranial volume, sex, social class and ethnicity, factors which were significantly associated with ventricular measures in the controls. There was no evidence of a threshold corresponding to the notion of normal versus enlarged ventricles. Within the schizophrenia group, there were no large or significant associations between ventricle dimensions and age at onset, duration of illness or pre-morbid social functioning. Neither obstetric complications nor a family history of schizophrenia or other psychiatric illness was associated with large ventricles in these cases.

Adolescent↗
PubMed1994

Upper respiratory tract illnesses and accidents.

Anecdotal accounts suggest that colds and influenza may increase human error. This view is supported by laboratory studies of the effects of upper respiratory tract illnesses (URTIs) on performance efficiency, which have shown that both experimentally induced and naturally occurring URTIs reduce aspects of performance efficiency. The present research examined the relationship between accidents and URTIs by studying 923 patients attending an Accident and Emergency department at a time of year when upper respiratory tract viruses were circulating. The results revealed no significant associations between URTIs and workplace accidents, and, similarly, no significant associations emerged when all accidents were compared with other attenders. The only effect which was close to statistical significance was a protective effect of influenza against workplace accidents, which could be explained in terms of a person with influenza or who has recently had influenza being less likely to work and therefore less likely to be at risk of experiencing a workplace accident. Further research must examine this topic with different methodologies, such as selecting controls from fellow workers of the index case, and these studies will provide us with a clearer view as to whether or not there is an association between URTIs and workplace accidents.

Accidents, Occupational↗
PubMed1994

Hepatitis B vaccination: how many doctors are fully covered?

Hepatitis B is an important health hazard to both health care workers and the patients they treat. Concerns over the safety of the original vaccine were reported in early studies as reasons for poor vaccine uptake amongst health workers. In this study, the overall uptake of a safe effective vaccine is still shown to be inadequate. However, a low perception of risk is the main reason stated for this behaviour. Needlestick injuries remain common, and a poor knowledge of action necessary is shown. A vaccine programme for junior housemen is shown to increase uptake substantially and is advocated for other grades.

Consultants↗
PubMed1993

Meta-analysis.

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Bias↗