Biomedical subjects
Publications and source records attributed to M Morgan.
Sixty mothers were randomly allocated to receive either 2 litres of crystalloid or 1 litre of colloid solution (hydroxyethyl starch) in order to preload the circulation prior to elective Caesarean section under epidural anaesthesia. There were no differences in the incidence of hypotension, degree of haemodilution, umbilical cord blood gas tensions or umbilical blood osmolalities between the two groups.
The self-reported smoking habits and intentions of over 10,000 adolescents, aged 11 to 16 years, were related to a variety of attitudinal and normative variables. Current or previous smoking experience was a more important predictor of future intention to smoke than attitude or subjective norm (others' perceived tolerance of subjects' smoking). Parental opposition to smoking was a more important direct predictor of subjects' smoking intention than parental smoking behaviour.
The incidence of sensory or language abnormalities and the factors influencing the clinical medical officers' decisions to refer children who failed developmental tests were studied. There were 1259 children examined and referrals for vision, hearing, and language assessment were made for 39(3.1%), 75(6.0%), and 27(2.1%), respectively. About 80% of these problems, however, were not known to the child health services when the children were 3.5 years old, mainly because children had moved to the district after the age of 3.5, and did not attend the 3.5 year screening clinics. Referrals formed only a small percentage of children who failed a test (11.0% failed vision, 19.5% hearing, and 24.6% language assessments). For vision and hearing the most important reason for the discrepancy was the clinical medical officers' wish to reassess children who failed the test before referring them. For the language test the clinical medical officer's often believed that the screening did not reflect the child's skills, which suggests that language screening as currently used in the district is not effective. Evaluation of the examination has highlighted the need to review the tests being used.
Coronary heart disease (CHD) mortality has declined in Britain since the early 1970s and followed a reduction in dietary fat intake in the population. We attempted to determine whether there have been changes in dietary fat intakes by social classes and to see whether they correspond to social class changes in CHD mortality, where the greatest reduction has been in the upper social class groups. Dietary fat intake was specially obtained by social class on a household basis from the National Food Survey (NFS) for 1974 and 1981. The decline in saturated fat intake and increase in polyunsaturated fat is shown to have occurred in each social class group, although it was not possible to examine the data separately for men and women. In contrast, the decline in the proportion of current smokers between 1974 and 1980 (from the General Household Survey) was greatest in the higher social classes. Rates of CHD mortality showed the greatest decline among men in social classes I & II over the period 1969/73 to 1979/83. However, despite some problems in the interpretation of the data collected by the NFS, this study shows that recent social class trends in dietary fat intakes are unlikely to account for the differential changes in CHD mortality. Changes in the prevalence of smoking among social classes are more consistent with the change in CHD mortality.
Drinking beliefs and behaviors were investigated in a survey of 2,700 Irish postprimary students. Overall, 47% of the students reported drinking within the month prior to the survey. Drinking was most frequent among older students and males. A regression analysis indicated that perceived peer drinking was the primary predictor of current alcohol use. Smoking and involvement with other problem behaviors were also important, and parental disapproval had a small effect. This pattern of results is similar to that found in other countries and provides evidence for the applicability of social learning and problem behavior theories to an understanding of adolescent drinking in another cultural context.
The role of child health clinics in an inner London district was examined by a survey of attenders at 52 baby clinic sessions run by the health authority and a review of the uptake of screening. Differences between social groups were examined using A Classification of Residential Neighbourhoods (ACORN) which is based on census data and requires only the full postcode to classify people. Clinic attendance was frequent among all social groups when a child was aged under six months but then declined, mainly reflecting changing needs. About one-half of the attenders saw the clinic doctor, often following referral by the health visitor, with 15% consulting about physical health problems. Differences occurred between ACORN groups in their frequency and reasons for clinic attendance after six months of age and rates of referral following developmental screening. This suggests that ACORN may be of value in monitoring service use and identifying groups with particular needs for services.
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We have examined the variation in receptor density and area among neurite-associated acetylcholine receptor patches (NARPs) induced by chick ciliary ganglion neurons on nearby myotubes in vitro. Quantitative analysis of rhodamine-alpha-bungarotoxin (RBTX) NARPs revealed that about 15% of the NARPs were "outstanding" in terms of size (greater than 60 micron 2) and fluorescence intensity (greater than 100 units on a 0-255 scale). The total number of receptors at different NARPs ranged over 3 orders of magnitude. It is likely that variation in NARP size and intensity reflects regional variation in the ability of myotubes to respond to the neuronal influence because (1) no gradient in NARP size or intensity with distance from the soma was evident; (2) the intensities and areas of uninnervated receptor clusters (hot spots) were similar to those of NARPs; (3) acetylcholinesterase was present at the same proportion of hot spots and NARPs at all times examined. We found no physiological or morphological evidence that outstanding NARPs were more effective sites of transmitter release. Outstanding NARPs were restricted to the longest neurite of individual neurons, so they may signal trophic interactions of the sort that promote neurite outgrowth and survival.
A modification of an enzyme-linked immunosorbent assay (ELISA) for the quantitative determination of plasma quinine levels is described. The test is rapid, sensitive and reproducible.
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The performance of the Stihler 1FT 200 blood warmer was evaluated at flow rates from 25 to 150 ml/minute and compared with that of the Hetotherm and Fenwal warmers. The Fenwal proved to be an efficient apparatus at all flow rates but the performance of the Hetotherm fell off slightly at higher flow rates. The Stihler 1FT 200 did not meet requirements for use in the operating room.
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The haemodynamic response to tracheal intubation was compared in 303 patients in whom anaesthesia was induced with either thiopentone 4 mg/kg, etomidate 0.3 mg/kg or propofol 2.5 mg/kg, with and without fentanyl 2 micrograms/kg. There was after propofol alone a significant decrease in arterial blood pressure, which did not increase above control values after intubation. Significant increases in arterial pressure followed intubation in patients induced with thiopentone or etomidate alone. Increases in heart rate occurred with all agents after laryngoscopy. The use of fentanyl resulted in arterial pressures lower than those after the induction agent alone, and in an attenuation, but not abolition of the responses to laryngoscopy and intubation.
Stimulation of left ventricular stretch receptors has been proposed as a possible mechanism for the occurrence of cardiac pain. Changes in left ventricular volume were continuously assessed in 12 patients during 11 spontaneous (two painful) and 12 ergometrine-induced (nine painful) ischemic attacks with a precordial scintillation probe and blood pool labeling with technetium-99m. In all ischemic episodes, spontaneous or induced, painful or painless, severe dilatation of the left ventricle was consistently observed. These changes always preceded the onset of ST segment shifts and occurred long before pain, when present. The maximum increase in end-diastolic volume was slightly greater in painful than in painless episodes, 38 +/- 8.0% versus 28 +/- 12.4%, but no significant difference was observed in the rate of volume change or in the maximum increase of end-systolic volume (133 +/- 50% and 110 +/- 27.3%), stroke volume (-28 +/- 15% and -25 +/- 12.4%), or ejection fraction (-32 +/- 8.7% and -26 +/- 6.0%). Although the maximum end-diastolic volume achieved is greater in painful episodes, this effect cannot be separated from that of duration, and, furthermore, there was no significant difference in end-diastolic volume at the moment chest pain began. Thus, in patients with angina at rest, transient asymptomatic ST segment shifts are consistently associated with large changes in left ventricular volume, similar to those observed during painful episodes. The rate and extent of acute left ventricular dilatation do not appear to be factors directly causing anginal pain.
The ventilatory effects of a propofol infusion were studied in 10 females premedicated with atropine and nine with papaveretum and atropine. The infusion, at a rate of 20 mg kg-1 h-1 for 5 min, reducing to 12 mg kg-1 h-1 for 10 min and then 6 mg kg-1 h-1 thereafter, was known to produce a steady-state plasma propofol concentration for 20-25 min after 25 min from commencement. Minute ventilation, tidal volume, frequency and response to breathing carbon dioxide were measured before the infusion and during the steady-state period. Propofol decreased minute ventilation to 56% and 46% (P less than 0.01) of their mean control values in the atropine and papaveretum groups, respectively. Mean tidal volume was decreased to 41-44% (P less than 0.02) by propofol, but a tachypnoea observed in the atropine group during the infusion was absent in the papaveretum group. Propofol alone had no effect on the slopes of the carbon dioxide response curves but did produce a shift to the right (P less than 0.05). Following papaveretum premedication the minute ventilation-carbon dioxide response curve slope, was decreased to 55% of its mean control volume value by the infusion, but this failed to reach statistical significance.
The epidemiology, significance, and clinical consequences of influenza in the hospital setting were studied in a prospective surveillance of adults in an acute-care hospital during the 1986-1987 influenza season, specifically searching for cases of nosocomial influenza. A total of 43 cases of influenza A were identified; 17 cases occurred among working hospital employees, 14 cases occurred among patients in the emergency room or clinics, ten were community-acquired cases among hospitalized patients, and two cases were nosocomially acquired. The nosocomial influenza attack rate was 0.3 per 100 hospital admissions. Both cases of nosocomial influenza were associated with secondary pneumonias and prolongation of hospital stay. These cases might have gone unrecognized in the absence of an influenza surveillance program. A potential reservoir of infection was the health care providers caring for the hospitalized patients. Further systematic influenza surveillance is needed to assess the global medical and economic impact of nosocomial influenza on hospitals, rather than simply relying on reports of institutional outbreaks.