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Biomedical subjects

J F Stevens

Publications and source records attributed to J F Stevens.

At least 37 records · Page 2Linked to original sources
PubMed1989

Smoking and occupational allergy in workers in a platinum refinery.

OBJECTIVE: To test the hypothesis that smoking increases the risk of sensitisation by occupational allergens. DESIGN: Historical prospective cohort study. SETTING: Platinum refinery. SUBJECTS: 91 Workers (86 men) who started work between 1 January 1973 and 31 December 1974 and whose smoking habit and atopic state (on skin prick testing with common allergens) had been noted at joining. MAIN OUTCOME MEASURES: Results of skin prick tests with platinum salts carried out routinely every three to six months and records of any respiratory symptoms noted by the refinery's occupational health service. Follow up was until 1980 or until leaving refinery work, whichever was earlier. RESULTS: 57 Workers smoked and 29 were atopic; 22 developed a positive result on skin testing with platinum salts and 49 developed symptoms, including all 22 whose skin test result was positive. Smoking was the only significant predictor of a positive result on skin testing with platinum salts and its effect was greater than that of atopy; the estimated relative risks (95% confidence interval) when both were included in the regression model were: smokers versus non-smokers 5.05 (1.68 to 15.2) and atopic versus non-atopic 2.29 (0.88 to 5.99). Number of cigarettes smoked per day was the only significant predictor of respiratory symptoms. CONCLUSION: Smokers are at increased risk of sensitisation by platinum salts.

Adolescent↗
PubMed1988

Clinical laboratory environmental contamination: use of a fluorescence/bacterial tracer.

A "Centrifichem" centrifugal analyser was found using a double fluorescence/bacterial tracer method to be a source of airborne and surface contamination in the laboratory. The airborne contamination was controlled by a modification incorporating a filter. Ubiquitous surface contamination generally accompanied the processing of simulated patients' sera. Double tracer samples could be used in laboratories to assess the quality of hygiene practices in the same way as quality control samples are currently used to assess the quality of analytical performance. The findings indicated a lack of understanding of basic hygiene practices in the laboratory.

Air Pollutants↗
PubMed1988

Improved financial management of the radiology department with a microcosting system.

The basic unit of service in radiology is the examination or procedure and its associated costs such as film, medical and surgical supplies, personnel, equipment depreciation, and overhead. The appropriate allocation of all operating costs to the specific examination types is the purpose of the microcosting system. Microcosting programs use data from hospital expense and payroll systems and data from a radiology information management system. These data are loaded into a computer spread sheet program for the microcosting computations. The results from using this system include better understanding of costs, accurate budget projections, confidence in negotiating discounts, and improved efficiency and reduced costs.

Accounting↗
PubMed1985

Electrodes in clinical chemistry.

On theoretical grounds it would appear preferable to use calibrants which are not adjusted to a constant ionic strength, whether concentration or activity is being estimated directly. For indirect methods, when sample and calibrant are diluted in an ionic strength adjusting buffer, there is probably little difference between adjusted and unadjusted calibrants. In this case a simple calculation of concentration is possible. A simple algorithm may be used for activity estimation. The algorithm for direct concentration estimation is more complex. If concentration, rather than activity, is required an indirect method must be used. If activity is required a direct method must be used. The quantitative effects of variations in calibration procedure may be smaller than variations in junction potential.

Chemistry, Clinical↗
PubMed1983

A simple numerical discriminant in the follow-up of lung cancer.

Statistical analysis of laboratory data obtained during a study on a group of patients with lung cancer suggests that a simple numerical discriminant may have value in the follow-up of such patients. The discriminant is based on six common laboratory tests and is rapidly derived in the consulting room using a simple pocket calculator.

Follow-Up Studies↗
PubMed1983

Application of reflectance spectroscopy to the estimation of uric acid, urea and glucose: an evaluation of the Ames Seralyzer.

An original approach to the measurement of analytes in clinical chemistry has now become available, in which dry reagent strip technology is linked to measurement by reflectance spectroscopy. The present studies have evaluated the performance of the first of these test systems-for uric acid, urea and glucose, in serum-by comparison with conventional liquid chemistry methods. Satisfactory performance in terms of both precision and accuracy was obtained for all three test systems, the current "state-of-the-art" performance criteria being met; the Seralyzer system proved reliable and easy to use in the hands of trained operators. It should find a place as a "Stat" analyser in the laboratory, in specified wards and in Health Centres.

Blood Glucose↗
PubMed1983

Measurement of the enzymes lactate dehydrogenase and creatine kinase using reflectance spectroscopy and reagent strips.

Two new methods for the assay of total activities of lactate dehydrogenase and creatine kinase are described, in which the enzyme activities are measured from a solid-state reagent strip during a kinetic reaction, the reaction being monitored in the ultra-violet region of the spectrum by reflectance spectroscopy. The performances of these methods are evaluated, and compared to conventional "wet" chemistry methods. The solid-phase reagent methods demonstrated precision and accuracy acceptable for diagnostic purposes, and were easy to use by trained operators.

Clinical Enzyme Tests↗
PubMed1980

Accuracy and linearity of spectrophotometers in clinical chemistry laboratories.

Solutions of cobalt nitrate sealed in vials were circulated to all clinical chemistry laboratories in the United Kingdom. Participants reported wavelengths of maximum absorbance together with the actual absorbances obtained. The results were compared with values obtained from the National Physical Laboratory. The results show a wide scatter, and several instruments were extensively repaired or replaced as a result of the survey. The most recently marketed machines had the best performance, and it is suggested that regular quality control and maintenance of the machines is vital. It is intended to set up a scheme for regular monitoring of spectrophotometer performance.

Cobalt↗
PubMed1980

Preoperative carcinoembryonic antigen and survival after resection of lung cancer.

Carcinoembryonic antigen (CEA) was measured preoperatively in 43 patients who underwent complete resection of primary lung cancer. 7 of 43 patients (17%) had CEA levels in the cancer diagnostic range (greater than 40.9 microgram/litre), non of whom survived longer than 10 months. At two years, it was apparent that those patients with a preoperative CEA less than 21 microgram had a better survival rate than those with a CEA21-40.9 microgram/litre (P less than 0.005).

Carcinoembryonic Antigen↗
PubMed1976

Introduction of a Vickers M300 analyser into the routine service of a hospital laboratory. 1. Installation, staffing, logistics.

A Vickers M300 analyser has been successfully installed in a busy hospital laboratory. A permanent team of operators is used, but this introduces problems for staff rotation, particularly for educational purposes. The vials used for the collection of samples are an essential feature of the system, but they present many difficulties and are no longer used for collecting samples from outpatients, or at remote sites. Direct costs during 1974, excluding staff and depreciation, amounted to approximately pounds 0-45 per patient sample: this is assessed on the rising workload during implementation. An increased workload could still be handled with existing staff. The siting of such high-capacity analysers constitutes an important policy decision.

Autoanalysis↗
PubMed1976

Introduction of a Vickers M300 analyser into the routine service of a hospital laboratory. 2. Tests, methods, evaluation.

A Vickers M300 analyser has been introduced into a busy hospital laboratory; a profile of 13 biochemical tests is currently provided. Analytical performance has been assessed over one year of routine service operation, and mechanical performance has been assessed over two separate three-month periods. At its best, the M300 achieves high standards of precision and accuracy and has the advantage of unrivalled speed. Enzyme assay methods are less satisfactory than the kinetic assays in current use. Random analytical errors occur and are difficult to detect. The restricted facilities of the integral process-control computer are inadequate for effective quality control.

Autoanalysis↗