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Biomedical subjects

R Lapworth

Publications and source records attributed to R Lapworth.

6 recordsLinked to original sources
PubMed1994

Laboratory blunders revisited.

Blunders which occurred over a 1 year period in the clinical chemistry departments of two health districts were recorded and categorized according to type and detection stage. A blunder was defined as an incident leading to an incorrect result/set of results either being reported or detected at the final checking-out stage in the laboratory. Of the total of 120 blunders--which is a blunder rate of less than 0.1% of requests--53 (44%) were detected at the final checking-out stage. Blunders detected after the report had left the laboratory were divided into those subsequently picked up by laboratory personnel (23); those detected by clinicians (19); and those by external quality assessment schemes (21). The types of blunder were fairly equally distributed between the booking-in (36), analysis (38), and reporting (35) stages of the laboratory process. A formal review of blunders detected in laboratories is a valuable aid to overall performance.

Chemistry, Clinical↗
PubMed1989

18-Hydroxycorticosterone as a marker for primary hyperaldosteronism.

An assay for the measurement of 18-hydroxycorticosterone (18-OHB) in plasma has been validated. The method involves extraction of plasma with dichloromethane, thin layer chromatography and radioimmunoassay with an iodinated 18-hydroxycorticosterone-3-carboxymethyloxime ligand. The plasma concentration of 18-OHB was measured in 16 patients with primary hyperaldosteronism and 20 control subjects. After overnight recumbency a significantly higher mean concentration of 18-OHB was found in the samples taken from the patients than in those from the control subjects. The degree of elevation did not clearly discriminate between patients with a unilateral adenoma and those with bilateral adrenal hyperplasia. A significant anomalous postural decrease in the 18-OHB concentration occurred in 10 of the 13 patients with an adenoma, whereas there was a significant postural increase in the three patients with hyperplasia.

18-Hydroxycorticosterone↗
PubMed1988

Low dose infusion of atrial natriuretic peptide causes salt and water excretion in normal man.

1. The effects of low dose infusion of atrial natriuretic peptide (ANP) were observed in double-blind, placebo-controlled study in six fluid-loaded volunteers. After baseline observations, hourly increments of 0.4, 2 and 10 pmol min-1 kg-1 were infused with continuous observation of heart rate, blood pressure and cardiac output. Plasma ANP, aldosterone, and catecholamines, and urinary volume and sodium excretion, were estimated at half-hourly intervals. 2. ANP infusion resulted in an increase of 35, 98 and 207% in urinary sodium excretion and of 10, 20 and 71% in urinary volume when compared with placebo. Plasma ANP was markedly elevated above placebo levels only during infusion of 10 pmol of ANP min-1 kg-1. 3. No change in heart rate of blood pressure was noted during the study, but a significant fall in stroke volume index was observed during active treatment. Plasma levels of aldosterone and catecholamines were not significantly different on the 2 treatment days. 4. The potent natriuretic and diuretic effects of this peptide at plasma concentrations not significantly elevated from physiological suggest a hormonal role for ANP in the homoeostasis of salt and water balance.

Adult↗
PubMed1983

Angiotensin-converting enzyme and its clinical significance--a review.

There have been considerable advances in understanding the metabolic role of the endothelial lining cells of the blood vessels. Angiotensin-converting enzyme activity is concentrated in these cells, especially those lining the pulmonary circulation. The enzyme exerts control over systemic vascular tone indirectly through the powerful pressor effect of angiotensin II. A number of therapeutic agents are now available which directly inhibit converting enzyme activity and thereby effect a reduction in blood pressure. Macrophages are the source of increased angiotensin-converting enzyme activity commonly found in association with active sarcoidosis. A better understanding of this phenomenon may give fresh insight into this puzzling condition. Pulmonary endothelial metabolism is affected by lung injury and it is likely that in this situation changing activities of serum angiotensin converting enzyme may indicate the extent of damage and the response to therapy. The full clinical significance of serum ACE measurements has yet to be established. However, raised activities have been reported in a number of other conditions and diabetes mellitus and hyperthyroidism are of particular current interest. The numerous methods and reference ranges described in the literature for the measurement of serum ACE activity require further assessment, and there is a clear need for an accepted reference method.

Adolescent↗