Biomedical subjects
Publications and source records attributed to D Simpson.
A frame-based computer-aided learning system for use on microcomputers has been developed for teaching clinical chemistry. The system presents a case-study model that can be used by students to assess their ability to make a diagnosis, to select patterns of investigations and to institute treatment.
Three colorimetric techniques and one enzymatic technique have been compared with an HPLC method for the analysis of salicylate in the plasma of patients after self-poisoning with aspirin. The enzymatic technique was specific but expensive to perform. The colorimetric techniques were simple, cheap and precise. The Keller method, however, was susceptible to interference from endogenous substances. We report a modification of the Keller method that eliminates most of this interference and improves the accuracy of the analysis. The new method is easier and safer to perform under emergency conditions than the Trinder technique.
Of 68 admissions for lithium overdose over 16 years, 25 were due to therapeutic intoxication and 43 to deliberate self-poisoning. Three patients with therapeutic intoxication had acute diabetes insipidus with hypernatraemia. One of them had acute renal failure requiring dialysis, prolonged Parkinsonism and generalised myopathy. Twenty-two patients with therapeutic intoxication had peak serum lithium concentrations above the therapeutic range. In contrast, of 22 self-poisoned patients with peak serum lithium concentrations above the therapeutic range only 3 developed toxicity. The mean admission plasma urea concentration in patients with therapeutic intoxication was higher than in self-poisoned patients and the mean admission plasma bicarbonate concentration was lower. The mean serum lithium half-life in 8 patients with therapeutic intoxication was considerably longer than in 5 self-poisoned patients. Renal lithium clearance is enhanced by increased sodium excretion and we recommend that lithium toxicity be treated with saline diuresis and frusemide if fluid retention occurs. Haemodialysis is mandatory when renal failure is present, and may be indicated when serum lithium concentrations are very high or rising rapidly.
The toxicological screening of 200 urine samples from 55 known heroin users claiming to be abstinent revealed that in 18% of samples (24% of users tested) opiates were unexpectedly detected. Other substances, many of which were psychoactive drugs, were identified in 35% of samples. Cocaine was not detected in any samples. In addition, nicotine was found in 91% of users and caffeine in 44%. The data showed the presence of polydrug abuse in 29% of subjects and suggested there is an illegal supply of drugs originating from doctors' prescriptions. The requirement for more general use of toxicological screening and the implications of the results for management of drug takers in general practices are discussed.
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The use of high frequency jet ventilation in the management of a patient with fat embolism syndrome is described. Its principal advantage over conventional intermittent positive pressure ventilation is a reduction in the amount of sedation necessary.
This study considered 135 cases of chronic subdural haematoma following head injury in 1977 and 1978. The majority were in the older age group and more often males. Falls were the commonest cause. Among intracranial haematomas they carry a much better prognosis. However, there was a mortality rate of 9% and delay in diagnosis was the most likely preventable factor contributing to this. Accordingly the possibility of this complication after head injury should be known to those concerned in the later hospital treatment and follow-up management especially of older patients and alcoholics. When the diagnosis has been made, the preferred surgical method of treatment is drainage through burrholes. Follow-up CT scanning should be arranged usually about 8 weeks afterwards unless there are clinical indications for an earlier examination.
An evaluation of a commercial TLC Kit System (Toxi-Lab) is described. The performance of the system is assessed in the detection of drugs in overdose and in therapy, and is compared with a GC drug screening system. Toxi-Lab performed well in investigating drug overdoses. We found data on metabolite patterns essential for the identification of drugs in urine and for this reason the system performed much better than GC screening in which information on metabolites is limited. In our experience Toxi-Lab screening was not sufficiently sensitive for the detection of commonly prescribed psychiatric drugs taken in therapeutic doses. This system is rapid, versatile and suitable for small laboratories, but is comparatively expensive and some expertise is necessary to interpret results. A major deficiency of the kit is that the identification procedures are designed for the detection of drugs available in the USA and many drugs prescribed in the UK have been omitted.
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This article compares statistical indicators of health with those of material and social deprivation for 28 wards of the city of Bristol, England. Four general indicators of health were examined-a combined rate per 1,000 live births of stillbirths and infant deaths; deaths of persons aged 15 to 64 per 1,000 of that age; deaths of persons aged 65 and over per 10,000 of that age, and numbers of babies born after 40 weeks gestation weighing less than 2,800 (and 2,500) grams per 1,000 births having that period of gestation. Measures of average and cumulative rank were used to augment tests of the significance of correlations between different indicators. The degree of rank consistency was high, and several wards at the top and the bottom of the rankings were clearly distinct on all indicators. Five indicators of deprivation were also examined-the percentages of: 1) households with fewer rooms than persons; 2) households lacking a car; 3) economically active persons seeking work; 4) children aged 5 to 15 who receive school meals free; and 5) households experiencing disconnection of electricity in the previous 12 months. Again the consistency of ranking according to the five indicators was high, with marked differences on all five indicators between the highest and lowest ranking wards. Between 1971 and 1981 some forms of deprivation increased in nearly all wards. According to some criteria, deprivation increased more in wards already most deprived in 1971 than in those least deprived. Finally, a strong association between the two sets of indicators was found. On the data available to health and planning authorities poor health is significantly correlated with deprivation. There are therefore implications for new forms of joint policy-making on the part of different departments of local and central government.
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The role of glycosylation in the maturation of the vesicular stomatitis virus (VSV) glycoprotein was studied by use of the antibiotic tunicamycin. Tunicamycin-treated VSV-infected cells synthesize an unglycosylated form of the VSV glycoprotein (R. Leavitt, S. Schlesinger, and S. Kornfeld, J. Virol. 21:375--385, 1977). We have found that tunicamycin has no effect on the attachment of the glycoprotein to intracellular membranes or on the transport of protein to the lumen of the endoplasmic reticulum. However, tunicamycin prevented the migration of the glycoprotein from the rough endoplasmic reticulum to smooth intracellular membranes.
The peak-monitor software of the Technicon SMAC system has been investigated by experiments designed to test its ability to detect abnormally shaped peaks, deliberately produced by presenting serum samples of inadequate volume for analysis. The software provided by the manufacturer is shown to detect faulty peaks inefficiently, and a set of modified parameters has been identified which greatly improves the performance of the peak-monitor software.
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