Showing papers by "George Davey Smith published in 1991"

Lay epidemiology and the prevention paradox: the implications of coronary candidacy for health education

Abstract: This paper is concerned with the appropriateness of current attempts to prevent chronic disease through behavioural change. Based on extensive ethnographic research in South Wales, the paper suggests that, within contemporary British health culture, there exists a well developed lay epidemiology which has a significant bearing on the public plausibility of modern health promotion messages. The paper describes the notion of the coronary candidate (the ‘kind of person who gets heart trouble’) and discusses the operation of the idea in everyday life. The manner by which lay epidemiology and the population approach to health promotion construct the ‘prevention paradox’ within the social world is outlined. In conclusion it is suggested that lay epidemiology readily accommodates official messages concerning behavioural risks within the important cultural fields of luck, fate and destiny. This simultaneously constitutes a rational way of incorporating potentially troublesome information, and a potential barrier to the aims of health education.

Transmission electron microscope investigations of the structure of copper precipitates in thermally-aged Fe—Cu and Fe—Cu—Ni

Abstract: Conventional transmission electron microscopy (TEM) and high-resolution electron microscopy (HREM) experiments have been carried out on thermally-aged binary Fe 1·30 wt% Cu and ternary Fe 1·28 wt% Cu 1·43 wt.% Ni alloys to study the structure of small (7–15 nm) copper precipitates in the α-Fe matrix. The experiments show that the precipitates have a twinned 9R close-packed structure, rather than the expected f.c.c. structure. It is believed that this structure is generated initially by a martensitic transformation from the metastable b.c.c. phase.

Construction and beam test of the ZEUS forward and rear calorimeter

Abstract: The forward and rear calorimeters of the ZEUS experiment are made of 48 modules with maximum active dimensions of 4.6 m height, 0.2 m width, 7 λ depth and maximum weight of 12 t. It consists of 1 X 0 uranium plates interleaved with plastic scintillator tiles read out via wavelength shifters and photomultipliers. The mechanical construction, the achieved tolerances as well as the optical and electronics readout are described. Ten of these modules have been tested with electrons, hadrons and muons in the momentum range 15–100 GeV/ c . Results on resolution, uniformity and calibration are presented. Our main result is the achieved calibration accuracy of about 1% obtained by using the signal from the uranium radioactivity.

Lay epidemiology and the rationality of responses to health education.

Abstract: Health education has long been seen as an important component of primary care, and under the new contract has become routine. It is important to consider the likely impact of general practitioners' endeavours in the light of the experience of health education to date. Despite decades of efforts directed towards reducing the population's adherence to practices deemed harmful to health, it must be acknowledged that the impact of such activity has been disappointing. This paper considers some cultural origins of public scepticism to health education messages, and argues for a more balanced presentation of current knowledge concerning the causes of disease and the probability that individuals will benefit by changing their behaviour.

Socioeconomic Differentials in Cancer among Men

Abstract: The relationship between cancer and socioeconomic position is examined for men using data from three sources--the Whitehall Study of London civil servants, the OPCS Longitudinal Study and the Registrar General's Decennial Supplement. Mortality from, or registration for, malignant neoplasms was higher overall in lower socioeconomic groups. There was considerable variation in the strength, and to a lesser extent direction, of the association of specific cancer sites and socioeconomic position within each of the studies. However, between the studies the relationships between socioeconomic position and the particular cancers were very similar. The similarity in results, taken in conjunction with the differences in design and methods of the three studies, makes it very unlikely that these consistent associations are due to artefacts. The heterogeneity in relationships between specific cancer sites and socioeconomic position suggests that no single factor--such as differences in general susceptibility or differences in smoking behaviour--can account for these associations. However socioeconomic differentials displayed by a particular malignancy do offer clues to its aetiology, and provide an indication of the scope that exists for reducing the burden of cancer within a population.

Why do child mortality rates fall ? An analysis of the Nicaraguan experience

Abstract: A comprehensive review of available sources of mortality data was undertaken to document the changes that have occurred in infant mortality in Nicaragua over the last three decades. It was found that a rapid fall in infant mortality commenced in the early 1970s and has continued steadily since. Trends in several different factors which might have led to this breakthrough were examined including: income, nutrition, breastfeeding practices, maternal education, immunizations, access to health services, provision of water supplies and sanitation, and anti-malarial programs. Of these, improved access to health services appears to have been the most important factor. At a time when the number of hospital beds per capita was dropping, increasing numbers of health care professionals, particularly nurses, were becoming available to staff primary health care facilities built in the 1960s. These were provided at least partly in response to the growing political turmoil enveloping the nation at that time. Certain Nicaraguan cultural attributes may have added to the impact of the reforms. Efforts in the field of public health made since the 1979 insurrection appear to have maintained the decline in child mortality.

Intravenous lignocaine and sympathoadrenal responses to laryngoscopy and intubation. The effect of varying time of injection.

Abstract: Summary We have studied the effect of varying the timing of a prior dose of intravenous lignocaine 1.5 mg/kg on the cardiovascular and catecholamine responses to tracheal intubation. Forty healthy patients were given an intravenous injection of either placebo or lignocaine 2, 3 or 4 minutes before tracheal intubation. There was a significant increase in heart rate of 21–26% in all groups. There was no significant increase in mean arterial pressure in response to intubation in any group of patients given lignocaine before intubation, but in the placebo group, mean arterial pressure increased by 19.1% compared to baseline values (p < 0.05).

Water Supply, Sanitation and Diarrhoeal Disease in Nicaragua: Results from a Case-Control Study

Abstract: In 1986-1988 researchers visited houses in rural Villa Carlos Fonseca in Nicaragua to learn what types of water supplies and sanitation levels existed and took monthly water samples to test for fecal coliforms. They studies 1229 diarrhea case-control pairs from the 1 health center in the area and from 5 of the 6 health posts to determine the relationship between acute diarrhea and environmental risk factors. Microbiological water quality and presence of a latrine were not significantly related to diarrhea morbidity. Access to water was significantly associated with diarrhea (adjusted odds ratio [AOR] 7.24; p 4 such children the diarrhea rate stood 70% higher than in houses with only 1 child. The rate was 22% higher for houses with 2-4 children. In conclusion diarrhea prevention efforts should concentrate on water availability and not water quality.

Influence of human insulin on symptoms and awareness of hypoglycaemia: a randomised double blind crossover trial.

Abstract: OBJECTIVE--To investigate the apparent increased risk of severe hypoglycaemia associated with use of human insulin by comparing the pattern of symptoms of hypoglycaemia with human insulin and porcine insulin. DESIGN--Randomised controlled double blind crossover trial of treatment with human insulin and porcine insulin, with two treatment periods of six weeks. SETTING--Diabetes outpatient department of a university teaching hospital in Berne, Switzerland. PATIENTS--44 patients (25 men, 19 women) aged 14 to 60 years, with insulin dependent diabetes mellitus. All patients met the following criteria: receiving treatment with fast acting soluble insulin and long acting protamine insulin; performing multiple daily fingerstick blood glucose self measurements; and had stable glycaemic control with about one mild hypoglycaemic episode a week during the preceding two months. INTERVENTION--Patients were randomised to receive either human or porcine insulin for six weeks and were then changed over to the other type of insulin for a further six weeks. MAIN OUTCOME MEASURE--Questionnaire recording "autonomic" and "neuroglycopenic" symptoms that occurred during hypoglycaemic episodes confirmed by a blood glucose concentration less than or equal to 2.8 mmol/l. RESULTS--Insulin doses and blood glucose, glycated haemoglobin A1c, and fructosamine concentrations were similar during the two treatment periods. 493 questionnaires on hypoglycaemia (234 during treatment with human insulin and 259 during treatment with porcine insulin) were analysed. With human insulin patients were more likely to report lack of concentration (52% v 35%, p = 0.0003) and restlessness (53% v 45%, p = 0.004) and less likely to report hunger (33% v 42%, p = 0.016) than during treatment with porcine insulin. The difference in the pattern of symptoms during the two treatments was similar to that between the 12 patients with a history of recurrent hypoglycaemic coma and the 32 patients without such a history. CONCLUSIONS--The pattern of symptoms associated with human insulin could impair patients' ability to take appropriate steps to avoid severe hypoglycaemia. Caution should be exercised when transferring patients from animal insulin to human insulin, and a large scale randomised trial of the two types of insulin may be justified.

Risk of severe hypoglycaemia in insulin treated diabetic patients transferred to human insulin: a case control study.

Abstract: OBJECTIVE--To examine whether transfer from animal insulin to human insulin is associated with an increased risk of severe hypoglycaemia. DESIGN--Matched case-control study of insulin treated diabetic patients admitted to hospital because of hypoglycaemia during 1984-7, the period when human insulin was introduced into treatment. SETTING--Case admissions and control admissions were obtained from eight public hospitals within the Swiss canton of Berne and a second control group comprised members of the Bernese section of the Swiss Diabetes Association. SUBJECTS--94 patients with insulin treated diabetes with a total of 112 admissions for hypoglycaemia during 1984-7 (case admissions), 182 patients with insulin treated diabetes seen in the same hospitals for reasons other than hypoglycaemia with a total of 225 admissions (control admissions), and 86 insulin treated diabetic patients who were members of the Bernese section of the Swiss Diabetes Association. MAIN OUTCOME MEASURES--Type of insulin used at time of admission, glycaemic control as measured by amount of glycated haemoglobin or glucose concentration; severity of hypoglycaemia. RESULTS--Treatment with human insulin at admission was more common in cases than controls (52/112 (46%) admissions v 77/225 (34%); p = 0.003). 116 out of 129 (90%) of admissions taking human insulin had been transferred from animal insulin, mainly because of non-availability of porcine insulins. The ratio of rate of hypoglycaemia in those taking human insulin to the rate in those taking animal insulin was 2.4 (95% confidence interval 1.3 to 4.4). Other risk factors for hypoglycaemia were a history of hypoglycaemic coma (rate ratio of history to no history 3.8, 2.3 to 6.4) and good glycaemic control (rate ratio of good to poor control 3.9, 1.4 to 7.5). With multivariate analysis the increase in rate ratio associated with use of human insulin rose to 3.0 (1.4 to 6.4). Comparison with the diabetes association controls also showed an increased risk associated with use of human insulin (2.2; 1.1 to 4.8). CONCLUSIONS--Transfer of treatment from animal insulin to human insulin was associated with an increased risk of severe hypoglycaemia. Caution should be exercised when transferring diabetic patients to human insulin. Further studies are required to elucidate why this effect occurs.

Increasing incidence of hypoglycemic coma in children with IDDM.

Abstract: Objective To examine the incidence of hypoglycemic coma in children with insulin-dependent diabetes mellitus (IDDM) over 8 yr from 1981 to 1988 and to investigate the importance of residual β-cell function of HbA1 levels and other variables as risk factors for hypoglycemic coma. Research Design and Methods The study consisted of 155 children with IDDM aged < 16 yr at study entry. Mean age at onset of diabetes was 7.9 yr (range 1.1–15.6 yr). We made a prospective assessment of hypoglycemic coma episodes, with a standardized questionnaire, over a total observation time of 816.6 person-yr. Three monthly clinical and laboratory examinations, which included determinations of C-peptide and HbA1 levels, were conducted. We compared children with hypoglycemic coma (cases) with children without hypoglycemic coma (controls) in a case-control analysis matched for diabetes duration. Yearly incidence of hypoglycemic coma, calculated as the number of subjects having an attack in 1 yr divided by the cumulative number of person-years for that year, was measured. Univariate and multivariate odds ratios were calculated from logistic regression. Results Over the first 4 yr, the average yearly incidence was 4.4/100 person-yr compared with 7.4/100 person-yr during the later 4 yr ( P < 0.0001). This tendency was accompanied by intensification of insulin treatment with an increase in the mean number of daily injections and a decrease in mean HbA1 levels. In the case-control analysis, absent residual β-cell function was the most important risk factor for hypoglycemic coma (adjusted odds ratio 7.8, 95% confidence intervals 2.0–31.2), followed by near-normal HbA1 levels (adjusted odds ratio 4.5, 95% confidence intervals 1.9–10.5). Conclusions In this group of children, improvement of glycemic control apparently led to an increase in the incidence of severe hypoglycemia. In children with recurrent hypoglycemic coma and undetectable C-peptide levels, it may be safer to aim for somewhat less tight glycemic control.

Trends in mortality in Britain: 1920-1986.

Abstract: In Britain continuing declines in infant mortality have ensured that life expectancy at birth has consistently improved during this century. Life expectancy in middle ages showed small declines between 1921 and 1940, probably due to real increases in coronary heart disease and cancer mortality which were not counterbalanced by falls in infectious disease mortality of sufficient magnitude. The persistence of social class differentials during this period and the role of diet are discussed. It is suggested that the reversal in the trend in overall mortality seen earlier this century in Britain has implications for recent mortality trends in Eastern Europe.

Morphine compared with diamorphine. A comparison of dose requirements and side-effects after hip surgery.

Abstract: The dose requirements and side effects of morphine were compared with those of diamorphine administered by patient-controlled analgesia in 40 patients following elective total hip replacement. Patients were allocated randomly to receive in a double-blind manner either morphine or diamorphine for postoperative pain relief. There were no significant differences between the two groups with regard to postoperative sedation, nausea, well-being, pain relief and requirements for antiemetic drugs. The dose requirement for diamorphine was approximately 50% of that for morphine.

The effect of the trendelenburg position on lower oesophageal sphincter tone

Abstract: Summary Measurements were made of gastric, lower oesophageal and barrier pressures in the supine, moderate and steep Trendelenburg positions in 10 healthy female patients during balanced anaesthesia. Adoption of the Trendelenburg position resulted in no significant changes in any measurement, with the exception of a small increase (0.1 kPa) in intragastric pressure in the steep head-down position. We conclude that the steep Trendelenburg position should not predispose to regurgitation in healthy patients.

"Why do Child Mortality Rates Fall? An Analysis of the Nicaraguan Experience."

Abstract: A comprehensive review of available sources of mortality data was undertaken to document the changes that have occurred in infant mortality in Nicaragua over the last three decades. It was found that a rapid fall in infant mortality commenced in the early 1970s and has continued steadily since. Trends in several different factors which might have led to this breakthrough were examined including: income, nutrition, breastfeeding practices, maternal education, immunizations, access to health services, provision of water supplies and sanitation, and anti-malarial programs. Of these, improved access to health services appears to have been the most important factor. At a time when the number of hospital beds per capita was dropping, increasing numbers of health care professionals, particularly nurses, were becoming available to staff primary health care facilities built in the 1960s. These were provided at least partly in response to the growing political turmoil enveloping the nation at that time. Certain Nicaraguan cultural attributes may have added to the impact of the reforms. Efforts in the field of public health made since the 1979 insurrection appear to have maintained the decline in child mortality.

Assessment and treatment of childhood asthma.

Abstract: In June 1990 a meeting of Paediatric Respiratory Physicians was held near Adelaide. The guidelines for assessing and treating asthma as prepared by the Thoracic Society of Australia and New Zealand for the management of patients with asthma was considered. Although not explicitly stated, these guidelines were designed for adult asthmatics. There was complete agreement that a companion statement was needed to take into account differences between the management of children and adults. This document fulfils that role. Further recommendations are found in a statement prepared by Australian and New Zealand respiratory paediatricians following a workshop in June 1989. This present statement should be read in association with the previous documents.

New dimensions in atom probe analysis

Abstract: Abstract A new class of atom-probe instruments has recently been developed which combine single atom sensitivity mass spectrometry with position sensing, and have the potential of reconstructing nanometre-scale composition variations in three-dimensions. These techniques will be very powerful in the study of the early stages of phase transformations, and surface and interface segregation. Some recent results obtained with the first of these instruments, the position-sensitive atom probe, are described. Difficulties arise in this instrument when more than one ion is evaporated from the analysis area on a single field evaporation pulse, which can limit the accuracy of analysis performed on the resultant data. Other three-dimensional atom-probe instruments currently under development are described, and their expected performance in this respect is discussed. The significance of defining composition on the sub-nanometre scale is addressed, and the importance of atomic-scale modelling of the phenomena under investigation is indicated.

Comparison of the combined effects of atropine and neostigmine with atropine and edrophonium on the lower oesophageal sphincter.

Abstract: Summary In two groups (n = 11) of healthy patients, we have measured gastric, lower oesophageal and barrier pressures before and after antagonism of neuromuscular block during anaesthesia with nitrous oxide and isoflurane. In one group, atropine 1.2 mg and neostigmine 2.5 mg were given and in the second group atropine 0.6 mg with edrophonium 1 mg/kg. One minute after administration of the reversal agents, there was a significantly greater reduction in barrier pressures in the neostigmine and atropine group than in the edrophonium and atropine group, but subsequently, there was no significant difference between the two groups. We conclude that there is no clinical difference between the two reversal mixtures in terms of the risk of regurgitation in the immediate period after reversal.

Preparation of Some Pyrrole-3,4-dicarboxylic Acid Derivatives and the Crystal Structure of 2-Methylpyrrolo[3,4-c]pyrrole-1,3(2H,5H)-dione

Abstract: A series of pyrrole-3,4-dicarboxylic acid derivatives has been prepared, and the crystal structure of one, 2-methylpyrrolo[3,4-c]pyrrole-1,3(2H,5H)- dione, has been determined by X-ray diffraction and refined to a residual R 0.049 for 1415 observed reflections. Crystals are monoclinic, space group P21/c, with Z= 8 in a cell of dimensions a 14.775(3), b 7.0692(5), c 15.151(3)Ǻ, β 118.82(8)°. Strain in the planar fused ring system is evident from the widening of the external interring angles to 143°, and from the unusual substituent effects in the 13C n.m.r. spectra.

Intravenous Lignocaine and Sympathoadrenal Responses to Laryngoscopy and Intubation: The Effect of Varying Time of Injection

Abstract: Summary We have studied the effect of varying the timing of a prior dose of intravenous lignocaine 1.5 mg/kg on the cardiovascular and catecholamine responses to tracheal intubation. Forty healthy patients were given an intravenous injection of either placebo or lignocaine 2, 3 or 4 minutes before tracheal intubation. There was a significant increase in heart rate of 21–26% in all groups. There was no significant increase in mean arterial pressure in response to intubation in any group of patients given lignocaine before intubation, but in the placebo group, mean arterial pressure increased by 19.1% compared to baseline values (p < 0.05).

Human insulin: Authors' reply

Abstract: Dr Egger and colleagues' crossover study had reduced awareness of hypoglycaemia before their inclusion in the study. The patients had had diabetes for a mean of over 15 years; at least a quarter could therefore be expected to have some degree of unawareness of hypoglycaemia,6 and it is pertinent that 12 patients had a history of recurrent hypoglycaemic coma. If some of these patients had altered awareness of hypoglycaemia their preexisting modified symptom profile may have biased the results. The authors suggest that the fewer reported episodes of hypoglycaemia during treatment with human insulin implied that this insulin species had impaired recognition of hypoglycaemia. The ratios of blood glucose concentrations below 2-8 mmol/l during treatment with human versus porcine insulin (1:1 14) and of completed questionnaires during treatment with these insulins (1:1 1), however, attest to the conclusion that fewer episodes of hypoglycaemia had actually occurred. A lower frequency of hypoglycaemia of unchanged severity with human insulin suggests that an altered symptom profile is likely to be of limited importance. Their extrapolation to conclude that the risk of severe hypoglycaemia with human insulin will be increased by the modified pattern of hypoglycaemic symptoms is not justified. Less than 10% of episodes of severe hypoglycaemia are treated in hospital, so that the patients who were surveyed in their case-control study may represent an atypical group. Among the patients with hypoglycaemia treated in hospital glycaemic control was better in those treated with human insulin. Treatment that vigorously tightens glycaemic control increases the frequency of severe hypoglycaemia4 and reduces symptomatic awareness.8 Thus the increased incidence of severe hypoglycaemia in patients taking human insulin may reflect overzealous diabetic control and be unrelated to insulin species. The diabetic patients in the Swiss canton of Berne were apparently converted to human insulin by pharmacists and not under careful medical supervision. Assuming that the transfer from animal to human insulin was made at equivalent dosage, the altered pharmacokinetics and immunogenicity of human insulin would predispose to lower blood glucose concentrations and increase the risk of hypoglycaemia secondary to increased bioavailability of human insulin.9 Because of an expected reduction in insulin requirement after transfer from animal to human insulin diabetic patients in the United Kingdom were instructed to reduce their dose of insulin by at least 10%, and few subsequently experienced increased hypoglycaemia. Although the progressive rise in the frequency of severe hypoglycaemia in Berne occurred in parallel with the increasing use of human insulin,, this simultaneous rise does not necessarily impute a causal relation. We submit, therefore, that neither of Dr Egger and colleagues' papers' indicates a relation between human insulin and a putative loss of awareness of hypoglycaemia in diabetic patients.

The position-sensitive atom probe : reconstruction of the atomic chemistry of solids in 3-dimensions (summary)

Abstract: A descriptive summary of the position-sensitive atom probe (POSAP), its applications to the study of nanoprecipitates and interfaces and recent methodological developments is presented.

Supercomputers in Materials Science

Abstract: A high performance graphics mini-supercomputer has been used for the visualisation and analysis of 3-dimensional atomic-scale chemical data from iron-chromium alloys obtained using the position-sensitive atom probe. This instrument allows us to follow the progress of phase transformation by spinodal decomposition which occurs in these alloys during thermal ageing. Experimental results are compared with the results of computer modelling of the atomic processes occuring during decomposition. Two types of modelling have been performed: Monte Carlo simulations and a numerical solution of the solid-state diffusion (Cahn-Hilliard) equation. It was found that both models produced similar microstructures to the experimental system, but the models differed in their later stages of development in a time regime where no experimental data was available.

Preparation of Some Pyrrole‐3,4‐dicarboxylic Acid Derivatives and the Crystal Structure of 2‐Methylpyrrolo(3,4‐c)pyrrole‐1,3‐(2H,5H)‐dione.

Abstract: A series of pyrrole-3,4-dicarboxylic acid derivatives has been prepared, and the crystal structure of one, 2-methylpyrrolo[3,4-c]pyrrole-1,3(2H,5H)- dione, has been determined by X-ray diffraction and refined to a residual R 0.049 for 1415 observed reflections. Crystals are monoclinic, space group P21/c, with Z= 8 in a cell of dimensions a 14.775(3), b 7.0692(5), c 15.151(3)Ǻ, β 118.82(8)°. Strain in the planar fused ring system is evident from the widening of the external interring angles to 143°, and from the unusual substituent effects in the 13C n.m.r. spectra.