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Biomedical subjects

D G Bullock

Publications and source records attributed to D G Bullock.

At least 19 recordsLinked to original sources
PubMed1999

The application of near patient testing to microbiology.

Near patient testing (NPT) was the norm in days when urine was examined by smell and taste. More recently, general practitioners and physicians in genitourinary medicine began to use light microscopes in their consulting rooms to examine urine for pus cells and urethral and other swabs for pathogens. Increasing knowledge has led to specialisation, however, with clinicians obtaining specimens for examination by others. Improved technology has speeded up the practice of medicine, raising expectations of patients and doctors alike, and reductions in the size and expense of testing instruments have made a renaissance of NPT possible. Such a rebirth has already been seen in high dependency units and neonatal intensive care units, where arterial blood gases and serum bilirubin have to be tested in less time than it would take a sprinter to reach the laboratory. People with diabetes, rushing about in the community, stop and test their own blood glucose to determine the ideal dose of insulin, and patients with asthma measure peak expiratory flow rates to titrate doses of inhaled and oral corticosteroids. To what extent has NPT developed in microbiology? General practitioners have nitrite dipsticks and dipslides with which to identify urinary tract infections and elsewhere in this issue the prospect for testing for Helicobacter pylori infection is discussed. Do-it-yourself HIV testing kits can be bought in some countries. Are these desirable developments for communicable diseases, the results of whose investigation are used not only to benefit the individuals tested but also to monitor trends in populations and determine policies for the prevention and control of infection? If NPT is desirable, or inevitable, in microbiology, how can it be developed so as to ensure a high quality service both for patients and the population? This review considers the implications of NPT in the field of communicable diseases for microbiology laboratories, quality assurance, accreditation, and the legal framework in which medical devices are used.

Accreditation↗
PubMed1995

External quality assessment schemes for clinical chemistry in the United Kingdom.

The system of UK national external quality assessment schemes (NEQASs) has been developed over more than 20 years, using logical criteria for scheme design and operation, and their usefulness is supported by evidence of continuing improved performance. The UK approach has built on the enthusiasm and knowledge of individual experts working to provide a fully integrated system of EQASs to facilitate the provision of reliable patient care.

Chemistry, Clinical↗
PubMed1994

The Zimbabwe External Quality Assessment Scheme (ZEQAS) in clinical chemistry: results of the pilot programme.

A pilot programme for assessing laboratory performance in clinical chemistry laboratories in Zimbabwe is described (ZEQAS). Twenty four laboratories providing patient care services participated. Eight lyphilised bovine sera were distributed over one year. Consensus values and the spread of interlaboratory agreement were calculated for each of 12 analytes and compared with results previously obtained in a large mature national EQA scheme in the UK (UK NEQAS). For all analytes except phosphate, the mean consensus value obtained in ZEQAS was between 94 and 108 pc of the UK target, although the spread of results in ZEQAS was generally two to threefold greater for individual analytes than in UK NEQAS. It is concluded the ZEQAS consensus values for the analytes surveyed provide a valid target against which individual laboratory performance can be assessed. The wide spread of results from individual laboratories suggests there is considerable scope for improving interlaboratory agreement. This is being addressed by the continuing programme, with increased interaction and production of local specimens.

Chemistry, Clinical↗
PubMed1993

Between-country comparability of clinical chemistry results: an international quality assessment survey of 17 analytes in six European countries through existing national schemes.

Two lyophilized control sera were distributed through seven national external quality assessment schemes in six European countries--Belgium, Switzerland, France, The Netherlands, Sweden and the United Kingdom--participated in the study. The results for 17 routine analytes were obtained from almost 5000 laboratories for the two sera. The organizers of the schemes were asked to process the results according to a common outlier removal procedure, and submit method-related data if available. The two sera were also distributed through the external/internal scheme of The Netherlands, and the within-laboratory standard deviations calculated in this scheme have been used in a scaling procedure for the external mean values and between-laboratory standard deviations of the participating countries. The results show remarkable agreement in the national mean values for practically all analytes, but considerable differences in the between-laboratory variation. Data from comparable method groups was obtained for 12 analytes from Belgium, France, The Netherlands and the UK. Though revealing some specific differences between methods and countries, the method-related data are generally in agreement with the all-method data. In this study reference method values were only available for cholesterol. The high degree of agreement found suggests, however, that mutual recognition of all-method mean values in national schemes could be acceptable, especially for analytes for which reliable reference methods are not available. The major element of variation is between-laboratory rather than between-country.

Animals↗
PubMed1993

Comparison of the use of a dry chemistry analyser in primary care in Norway and the United Kingdom.

The results of a quality assessment survey of the most commonly used dry chemistry instrument in primary care in Norway and the United Kingdom, the Reflotron (Boehringer), are reported including an evaluation of some of the operational characteristics of the Reflotron users. The primary care users in Norway taking part in the study comprised 95 occupational health care departments and 89 general practices. In the UK, primary care users taking part were 95 occupational health care departments and 37 general practices. In terms of both accuracy and precision evaluation of concentrations of bilirubin, cholesterol, gamma-glutamyl transferase, glucose, triglycerides, urea and uric acid by primary care users was similar in the two countries, and to that of 60 Norwegian laboratories. Examination of operational characteristics revealed a lack of effective quality control measures in both countries, and some differences in the pattern of usage between primary care users in Norway and the UK, especially in general practice. The result of Reflotron tests were ready before the patient left in a considerably higher proportion of general practices in the UK than in Norway. It is concluded that the Reflotron is suitable for primary care use, but good, routine quality of analysis must be ensured through collaboration between primary care users and clinical chemists.

Blood Chemical Analysis↗
PubMed1992

A reference preparation of human prostatic acid phosphatase: purification, characterization and field trials.

Acid phosphatase has been prepared in an apparently pure state by affinity chromatography from human prostatic tissue. When dissolved in an acidic albumin solution, lyophilized and stored at -20 degrees C for up to 2 years, no time-dependent loss of catalytic activity was detectable in the reconstituted material. Accelerated degradation tests also predicted complete stability. A preliminary distribution of the lyophilized preparation to 143 laboratories confirmed its robustness and demonstrated its potential usefulness as a calibrant to unify the results of different methods of measuring acid phosphatase activity.

Acid Phosphatase↗
PubMed1991

External quality assessment of total urinary protein estimation in the United Kingdom.

Three surveys of total urinary protein quantitation have been carried out in 350 UK laboratories. The seven specimens comprised buffered saline or normal human urine with added human serum albumin or human serum, or urine from individuals with nephrotic syndrome. Principal method groups were: turbidimetry (57%), dye binding (25%) and biuret (15%). For all surveys, overall between-laboratory agreement was poor (CV 22.8% to 57.1%), with ranges of results from 24-fold (0.83-20 g/L) to 366-fold (0.05-18.3 g/L); there was no improvement with time. The most popular method (sulphosalicylic acid turbidimetry) consistently performed the worst, and performance of the direct biuret procedure was also unacceptable; both methods should be discontinued. There were no significant differences in performance between the other major method groups, and none can be specifically recommended. Within the individual calibrant groups, least variation was observed with human serum. A common calibrant for all participants yielded significantly better between-laboratory agreement for all methods except sulphosalicylic acid turbidimetry.

Biuret Reaction↗
PubMed1991

UK external quality assessment scheme for immunoassays in endocrinology.

UK EQAS provide the UK with a comprehensive system for EQA in endocrinology, as well as in other aspects of clinical chemistry and laboratory medicine. UK EQAS in endocrinology are scientifically designed to yield an objective assessment of participants' performance and stimulate improvements in between-laboratory agreement. The design uses appropriate specimens, based on liquid human serum and prepared with minimal processing and additives in the organising centres to enable detailed study of recovery and other important factors. Target values are validated by reproducibility on repeated distribution and by recovery and parallelism studies. Reports are presented informatively, and emphasise the cumulative scoring system (bias and variance) for performance assessment. Computerised data processing and data presentation form an integral part of these schemes, and a common core computing system is in use throughout these UK EQAS. Participants receive advice and assistance in the interpretation of performance data and, when appropriate, in the resolution of problems.

Chemistry, Clinical↗
PubMed1990

Immunochemical assays of serum proteins: a European external quality assessment survey and the effects of calibration procedures on interlaboratory agreement.

An external quality assessment survey of immunochemical assays of 9 proteins (immunoglobulins G, A and M, complement components C3 and C4, alpha1-antitrypsin, orosomucoid, haptoglobin and transferrin) in 5 European countries (Austria, France, Hungary, Italy and UK) showed inter-country differences in the mean values obtained. Reprocessing of the results using one of the two specimens distributed as a 'calibrant' effectively eliminated or reduced substantially these differences. Consideration of the methods used by participants confirmed previous indications from national surveys that the differences were due to lack of agreement among commercial calibrants. Such interlaboratory variations were also minimised by the 'calibration' in this survey. The role of European working calibration materials in ensuring interlaboratory agreement on an international basis is discussed.

Blood Proteins↗
PubMed1990

Improving the quality of plasma cholesterol measurements in primary care.

During the last 2 years an external quality assessment (EQA) scheme has been developed for plasma cholesterol measurements made in primary care. The scheme, which is supported by the UK Department of Health and by the instrument manufacturers, now has over 300 participants, most of whom use the Boehringer Reflotron. Operators are mostly nurses, with little or no laboratory experience. To avoid matrix effects, fresh plasma specimens collected from normal volunteers and those attending a hospital lipid clinic are used. Three specimens, mostly with cholesterol concentrations in the range 5-9 mmol/L, are distributed every 2 months. The mean plasma cholesterol results show good agreement with those from 'reference' laboratories, and efforts are now being made to link these laboratories with the CDC-based reference system. The scheme uses a predominantly graphical presentation of results, with a greater element of interpretation by the organisers than is usually provided for laboratory-based participants. The distribution of results shows a higher proportion of outliers than in the UK national EQA scheme for laboratory cholesterol measurements. At present about 10% of participants in primary care obtain results which could be clinically misleading, and new approaches are needed in dealing with these 'poor performers'. This scheme could serve as a model for other assays in primary care. It illustrates the importance of training, quality assurance and education, and the need for laboratory staff to become more involved in this growing and important area of laboratory medicine.

Chemistry, Clinical↗
PubMed1989

Quality of plasma cholesterol measurements in primary care.

Three surveys were made of the quality of plasma cholesterol measurements performed with a commercial desktop analyser (BCL Reflotron) in primary care. Each survey included three specimens, and results were received from 37, 61, and 69 participants. Although many participants obtained satisfactory results, 8.6% of the results differed by 1.0 mmol/l or more from the target values, and the overall between instrument dispersion of results was 1.3 times that between hospital laboratories. It was found that common sources of error were poor technique and the use of outdated reagent strips. Users of such instruments outside the laboratory need help and advice with training, and guidelines for this are provided. The main recommendations are that users should establish contact with a local clinical chemistry laboratory for training and support and should participate in external quality assessment schemes.

Cholesterol↗
PubMed1989

Urinary total protein estimation--fact or fiction?

In two recent surveys of urinary total protein assays, 370 laboratories in the United Kingdom were requested to determine the protein content of a simulated 24-hour urine (a solution of sodium and potassium salts and urea, with no added protein) and of a 24-hour urine from a healthy individual. The nature of these specimens was not revealed and participants used their routine methods and calibrants. Quantitative results (range 0.005-12.23 g/l, median 0.03 g/l) were received from 31% of the participants for the salt solution and from 43% for the normal urine (range 0.01-2.96 g/l, median 0.05 g/l). Nonquantitative results, i.e. those given as less than a detection limit (range less than 0.005 to less than 0.5 g/l) were received from 29% of the participants for the salt solution and from 33% for the normal urine. Statements of 'nil', 'zero' or 'not detected' were received from the remainder. Further analysis of the results indicated that 29% of the laboratories reported, or did not unequivocally exclude, significant proteinuria in the salt solution, and 41% of the laboratories similarly did not exclude proteinuria in the normal urine. It is proposed, for both clinical and analytical reasons, that consideration be given to the discontinuation of urinary total protein estimation and that urinary albumin, supplemented where appropriate by other selected protein or enzyme measurements, be determined instead.

Albuminuria↗