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Biomedical subjects

G Lewis

Publications and source records attributed to G Lewis.

At least 199 records · Page 11Linked to original sources
PubMed1993

Another British disease? A recent increase in the prevalence of psychiatric morbidity.

AIMS AND OBJECTIVE: To examine trends in the prevalence of psychiatric morbidity in Britain between 1977 and 1985. DESIGN: Secondary analysis of two cross sectional population based surveys. SETTING: The first survey was conducted in 1977 in West London and the second in 1984-85 throughout Great Britain. PARTICIPANTS: Members of the public randomly selected from the electoral register. MEASUREMENTS AND MAIN RESULTS: The main outcome was the prevalence of psychiatric morbidity assessed using the General Health Questionnaire, a self administered measure of neurotic symptoms. There was an increase of at least 8% (95% confidence interval 6.6, 9.8) in the prevalence of psychiatric morbidity between the times of the two surveys and this difference persisted after adjustment for any changes in the sex, age, employment status, marital status, social class, and housing tenancy between the two samples. When the analysis was restricted to the Greater London respondents of the Health and Lifestyle Survey a larger increase in psychiatric morbidity was seen. CONCLUSIONS: It is likely that there was an increase in the prevalence of psychiatric morbidity in Great Britain between these two surveys. Psychiatric morbidity is a public health problem of some importance and the causes of this increase require further study.

Adolescent↗
PubMed1993

Cerebral oxygen metabolism during hypothermic circulatory arrest in humans.

Profound hypothermia with circulatory arrest is an important surgical adjuvant that allows protected cessation of cerebral blood flow for a brief period. In seven patients undergoing this procedure, continuous spectroscopic measurement of cerebral hemoglobin oxygen saturation was performed. Circulatory arrest at 18 degrees C was associated with a significant progressive desaturation (p < 0.01) of residual cerebral hemoglobin. Arrest time varied based on operative complexity (range 10 to 65 minutes), and a negative linear correlation between arrest time (y) and oxygen saturation (x) was noted (y = -0.87 x + 64). Five patients whose saturation remained above 35% had no neurological injury attributable to hypoxia. One patient (Hunt and Hess Grade 0) whose saturation fell below 35% had evidence of a global hypoxic injury at postmortem examination. Spectroscopically measured cerebral hemoglobin saturation (cerebral oximetry) may be used to monitor metabolic activity during circulatory arrest. Although the clinical utility of such monitoring cannot be established at this time, the potential may exist to prolong the safe duration of induced circulatory arrest for cerebral protection.

Adolescent↗
PubMed1993

Stress analysis of a flexible one-piece type first metatarsophalangeal joint implant.

Two-dimensional finite element analysis was used to obtain the magnitude and distribution of the stresses in models of two different designs of a flexible one-piece double-stemmed first metatarsophalangeal joint implant. The loading and constraint conditions have been reported by previous researchers to occur in vivo at the joint during the push-off phase of the normal walking cycle. Based on the results obtained, the authors recommend the direction that future studies in this area should take.

Humans↗
PubMed1993

Predictors of clinical wear of restorative dental composite materials.

The mode-I plane-strain fracture toughness values of eight posterior restorative composite materials were determined using straight-sided chevron-notch short-rod specimens and a special loading module. These results, together with the values of the modulus of elasticity, modulus of resilience, and flexural strength of these materials (as given in a paper by a previous worker) were used in a detailed correlational exercise, with the values of the clinical wear of restorations made from these materials (as given in the aforementioned paper) being the dependent variable. It was found that clinical wear may best be predicted using values of all four aforementioned mechanical properties.

Bicuspid↗
PubMed1992

Schizophrenia and city life.

Prevalence of schizophrenia and rates of first admission to hospital for this disorder are higher in most modern industrialised cities, and in urban compared with rural areas. The "geographical drift" hypothesis (ie, most schizophrenics tend to drift into city areas because of their illness or its prodrome) has remained largely unchallenged. We have investigated the association between place of upbringing and the incidence of schizophrenia with data from a cohort of 49,191 male Swedish conscripts linked to the Swedish National Register of Psychiatric Care. The incidence of schizophrenia was 1.65 times higher (95% confidence interval 1.19-2.28) among men brought up in cities than in those who had had a rural upbringing. The association persisted despite adjustment for other factors associated with city life such as cannabis use, parental divorce, and family history of psychiatric disorder. This finding cannot be explained by the widely held notion that people with schizophrenia drift into cities at the beginning of their illness. We conclude that undetermined environmental factors found in cities increase the risk of schizophrenia.

Adult↗
PubMed1992

Comparison of two self administered psychiatric questionnaires (GHQ-12 and SRQ-20) in primary care in Chile.

The General Health Questionnaire (GHQ-12) and the Self Report Questionnaire (SRQ-20) were simultaneously validated against the criterion of the Revised Clinical Interview Schedule (CIS-R) in a primary care clinic in Santiago, Chile. A Relative Operating Characteristic (ROC) analysis was used to determine the optimal threshold point for case definition and to compare the performance of these two questionnaires. The validation coefficients for the GHQ-12 and the SRQ-20 were, respectively: sensitivity 76% and 74%; specificity 73% and 77%; overall misclassification rate: 26% and 25%. Misclassification by these questionnaires was significantly associated with education and sex, males being more likely than females to be misclassified as false negatives and poorly educated respondents as false positives. The symptom response profile of both questionnaires showed that the most prevalent items were psychological complaints of anxiety and depression. Both instruments seem to have a similar ability to identify minor psychiatric disorders in primary care in Chile.

Adult↗
PubMed1992

Gallbladder perforation: preoperative diagnosis by combined imaging techniques.

Gallbladder perforation represents the most serious complication of cholecystitis. Rapid preoperative diagnosis is necessary because of the high morbidity and mortality associated with it. The authors present a case of gallbladder perforation in a 64-year-old man who had been on high doses of steroids. This case was diagnosed preoperatively by combined radiologic imaging methods.

Cholecystitis↗
PubMed1992

Effect of lithotriptor treatment on the fracture toughness of acrylic bone cement.

Extracorporeal shock wave lithotripsy (ESWL) has now been established as an efficacious non-invasive modality for the management of renal calculi and has shown promise for management of other types of stone, as well. Following on from these successes, ESWL has recently been proposed for use in the preliminary stages of revision of cemented total hip joint replacements as a means of breaking up the cement mantle. It is useful, therefore, to examine the effect of shock waves on pertinent mechanical properties of the cement. This study utilizes the chevron-notch short-rod specimen and a commercially available test system to obtain the values of one such property, namely fracture toughness, of Palacos Radiopaque bone cement before and after treatment with shock waves delivered from a lithotriptor. The fracture toughness drops by about 14% following the shock wave treatment, thus confirming the possibility that ESWL can be used, as indicated earlier, in revision arthroplasty.

Acrylic Resins↗
PubMed1992

Variation in the biological function of envelope protein epitopes of yellow fever vaccine viruses detected with monoclonal antibodies.

Three different virus strains (17D-204, 17DD and the French neurotropic vaccine) have been used as live attenuated yellow fever (YF) vaccines and are manufactured in different centres around the world. The envelope proteins of these vaccine viruses were examined and compared using mouse monoclonal antibodies (MAbs) in haemagglutination inhibition (HAI) and neutralization (N) tests. The epitopes eliciting HAI and/or N were found to vary depending on the virus examined. Such variation was also found between vaccine viruses of the same strain manufactured in different centres. These data were confirmed by the use of mouse polyclonal antisera. On the basis of the MAb results in HAI tests a dendrogram of the similarity coefficients between the viruses was constructed and showed that the viruses could be placed into three major groups. Thus, it is concluded that YF vaccines manufactured in different centres are antigenically distinct as recognized by the mouse immune system.

Antibodies, Monoclonal↗
PubMed1992

Measuring psychiatric disorder in the community: a standardized assessment for use by lay interviewers.

Many of the standardized interviews currently used in psychiatry require the interviewer to use expert psychiatric judgements in deciding upon the presence or absence of psychopathology. However, when case definitions are standardized it is customary for clinical judgements to be replaced with rules. The Clinical Interview Schedule was therefore revised, in order to increase standardization, and to make it suitable for use by 'lay' interviewers in assessing minor psychiatric disorder in community, general hospital, occupational and primary care research. Two reliability studies of the revised Clinical Interview Schedule (CIS-R) were conducted in primary health care clinics in London and Santiago, Chile. Both studies compared psychiatrically trained interviewer(s) with lay interviewer(s). Estimates of the reliability of the CIS-R compared favourably with the results of studies of other standardized interviews. In addition, the lay interviewers were as reliable as the psychiatrists and did not show any bias in their use of the CIS-R. Confirmatory factor analysis models were also used to estimate the reliabilities of the CIS-R and self-administered questionnaires and indicated that traditional measures of reliability are probably overestimates.

Adult↗
PubMed1992

Dimensions of neurosis.

Factor analyses of the General Health Questionnaire have attempted to interpret the factors as measuring anxiety, depression and social functioning. Data from two large community surveys were used to conduct an unrotated principal components analysis of the 30-item General Health Questionnaire. A general factor, indicating overall severity of psychiatric disorder, accounted for around 30% of the variance. The next most important factor, accounting for about 8% of the variance, was bipolar with the positive ('less than usual') items of the General Health Questionnaire having positive coefficients and the negative ('more than usual') items having negative coefficients. It is suggested that the concepts of positive and negative mental health derive empirical support from the results and may prove to be a useful classification of dimensions of mental health in the community.

Adult↗
PubMed1992

Regional differences in mental health in Great Britain.

STUDY OBJECTIVE: The aim was to study the pattern and magnitude of regional differences in psychiatric morbidity and compare these with regional differences in all cause mortality. DESIGN: The study was a secondary analysis of data from a cross sectional survey. The main outcome was the prevalence of psychiatric morbidity. This was assessed using the general health questionnaire, a self administered measure of neurotic symptoms. SETTING: England, Wales and Scotland. PARTICIPANTS: 9003 adults were selected from the electoral register. MAIN RESULTS: The prevalence of psychiatric morbidity was 31% with a statistically significant difference between the regions (p = 0.006). All four northern regions of England had a higher prevalence of psychiatric morbidity than the four southern regions. These differences were comparable in size to the regional differences in all cause mortality. Scotland had low psychiatric morbidity but high all cause mortality while Greater London had high psychiatric morbidity but low mortality. Regional variation in psychiatric morbidity was less marked within social classes I and II and among those living in urban areas. CONCLUSIONS: Psychiatric morbidity is common and is an important public health problem. Regions with relatively high psychiatric morbidity did not always have relatively high mortality. Knowledge of the causes of these regional differences could ultimately lead to preventive action and be important when distributing health service resources.

Cross-Sectional Studies↗
PubMed1992

Intracerebral penetration of infrared light. Technical note.

Near infrared transmission spectroscopy of the human cerebrum may allow noninvasive evaluation of cerebral hemoglobin saturation in humans. The emerging spectroscopy configuration for this application is a side-by-side source-receiver construct. The ability of this spectroscopy paradigm to detect changes in intracerebral attenuation by selective injection of the infrared tracer indocyanine green into the internal and external carotid arteries during endarterectomy is evaluated in five adult patients. In all five, simultaneous two-channel infrared transmission spectroscopy over the ipsilateral hemisphere documented tracer bolus transit with a signal-to-noise ratio greater than 100:1. In addition, the two channels could be configured to achieve depth resolution of the collected spectra.

Brain↗
PubMed1992

AIDS course: a university elective.

Developing and teaching a nonnursing elective on AIDS is both challenging and rewarding. We encourage nursing faculty elsewhere to teach an AIDS course for university students on their campus.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Observer bias in the assessment of anxiety and depression.

Two studies are described here. In the first, an attempt is made to examine the relationship between the complaints of anxiety and depression using the results of a survey of a dermatology clinic. The Hospital Anxiety and Depression scale (HAD) and Clinical Interview Schedule (CIS) were both used in 117 unselected clinic attenders. The results showed that the self-report scales (HAD and first section of CIS) showed a closer relationship between anxiety and depression than the second section of the CIS that requires clinical judgement. In the second study, an attempt was made to distinguish between two possible explanations for this phenomenon; that psychiatrists use the constructs of anxiety and depression more carefully than patients, or alternatively that psychiatrists show an observer bias. A sample of psychiatrists were asked to complete symptom profiles for anxiety and depression; both for an imaginary 'patient' and for their own emotions, allowing psychiatrists' beliefs concerning the relationship between anxiety and depression to be studied. The results indicated that the psychiatrists thought there was a negative correlation between anxiety and depression in patients in contrast to the consistent empirical finding that anxiety and depression are positively correlated. Psychiatrists also thought anxiety and depression were less closely related in patients than in themselves. It is likely that psychiatric assessments of anxiety and depression requiring clinical judgement on the part of the interviewer are subject to observer bias. It is argued that self-report measures of psychiatric symptoms will provide more convincing evidence to resolve diagnostic disputes.

Adult↗