Search PubMed⌕ Search

Biomedical subjects

R B Payne

Publications and source records attributed to R B Payne.

At least 37 records · Page 2Linked to original sources
PubMed1990

Hyperlactatemia and increasing metabolic acidosis in hepatorenal failure treated by hemofiltration.

We report a case of increasing hyperlactatemia in the course of repeated treatment by machine hemofiltration (MHF) using a lactate-buffered replacement solution. The hyperlactatemia was associated with a reduction in mean arterial pressure, and in the majority of treatments a metabolic acidosis developed. Hyperlactatemia due to exogenous lactate may not be as benign as previously discussed.

Acidosis, Lactic↗
PubMed1990

Albumin-adjusted calcium concentration in serum increases during normal pregnancy.

Concentrations of total calcium and albumin were measured in serum specimens from 41 women at intervals before, during, and after 42 pregnancies. The albumin concentration decreased but the calcium decreased more slowly, so that the albumin-adjusted calcium concentration increased from conception to term. These findings, taken in conjunction with published observations of hypercalciuria, increased concentrations of 1,25-dihydroxycholecalciferol and calcitonin in serum, and decreased concentrations of intact parathyrin in serum, strongly suggest that maternal ionized calcium increases throughout normal pregnancy.

Adult↗
PubMed1989

Psychomotor performance as a function of time of day.

Previously reported data on mirror tracking were reexamined for time-of-day (TOD) effects on performance and for the interaction of these effects with sex and practice effects. Analyses showed a significant linear decline of mean score from 0900 through 1300 hours, a sharp postlunch recovery at 1400 hours, and another significant linear decline from 1400 through 1700 hours. These effects were orthogonal to sex and practice effects. Discussion emphasized the importance of control for time of day in experimental design and suggested several hypotheses about the decremental effects of time of day.

Adolescent↗
PubMed1988

An isotonic potassium chloride liquid junction minimises the effects of ionic strength, protein and haematocrit on ionised calcium measurement.

When the reference electrode liquid junction of a Nova 2 analyser was changed to isotonic potassium chloride, increasing the ionic strength of aqueous solutions containing a constant total calcium concentration had a negligible effect on measured ionised calcium. In contrast, measurements using hypertonic potassium chloride, hypertonic sodium formate and isotonic sodium chloride liquid junctions showed significant sample ionic strength effects. Interferences by sample protein concentration and haematocrit were marked with hypertonic, but negligible with isotonic junctions. Ionised calcium values in samples containing 25 mmol/L acetate, bicarbonate, beta-hydroxybutyrate, lactate or pyruvate were all lower by 6-7% with an isotonic than a hypertonic potassium chloride junction. Thus, anions that replace bicarbonate during metabolic acidosis have a similar effect on residual liquid junction potential. The clinical usefulness of an isotonic potassium chloride liquid junction needs to be evaluated.

Calcium↗
PubMed1988

Serum albumin by dye-binding: bromocresol green or bromocresol purple? The case for conservatism.

Pooled patient's serum selected to have a wide range of albumin concentrations was analysed for albumin by bromocresol green with both long and short incubation times and also by bromocresol purple. Total protein, colloid osmotic pressure, calcium and magnesium were also measured. There were strong linear correlations between albumin measured by the three methods. Albumin values by bromocresol green with a short incubation time (1.5 min) averaged 5 g/L higher than those by bromocresol purple at all albumin concentrations. Colloid osmotic pressure correlated less strongly with total protein and with albumin by bromocresol purple than with albumin by the two bromocresol green methods. There were no significant differences between the correlation coefficients of calcium or magnesium with total protein and with albumin measured by the three methods. Bromocresol purple has no advantage over bromocresol green with a short incubation time for the clinical purposes for which albumin is measured: to detect abnormality, monitor change, predict colloid osmotic pressure and adjust calcium and magnesium for abnormal protein concentrations.

Bromcresol Green↗
PubMed1987

Protein interferes with ionised calcium measurement at the reference electrode liquid junction.

The ionised calcium concentration of sequential retentates prepared by ultrafiltration of a human control serum increased with increasing protein concentration when measured with both a Nova 2 and a Radiometer ICA1 analyser using their standard reference electrodes. In contrast, the ionised calcium in the same retentates fell slightly with increasing protein when the reference electrode liquid junctions of the instruments were changed from hypertonic to isotonic solutions, the values then paralleling those in the filtrates. Thus, the clinically significant positive relationship between ionised calcium and protein that has been reported with the Nova 2 and ICA1 analysers is almost certainly an effect of protein on the reference electrode liquid junction potential rather than a consequence of a Donnan effect on true ionised calcium distribution.

Blood Proteins↗
PubMed1986

Effects of workload and analysis time on the cost of out-of-hours investigations.

In the UK, under present Whitley Council Regulations for payment for out-of-hours pathology services, there is a complex relationship between the number of requests received, the time taken to analyse each request, and the number of calls for which payment may be claimed for work done. At a fixed average analysis time, the rate of increase of remuneration slows down as workload increases until at higher workloads remuneration falls. The introduction of methods with a shorter average analysis time to improve the clinical service increases remuneration disproportionately. We suggest that a fixed sessional payment would be a better way of funding the service.

Clinical Laboratory Techniques↗
PubMed1986

Sex-role effects (if any).

Two studies that seem to show conflicting effects of sex role on psychomotor reminiscence and performance are reviewed, and an effort is made to reconcile the discrepant results.

Female↗
PubMed1986

Rapid measurement of serum water to assess pseudohyponatremia.

Pseudohyponatremia is caused by an increased serum protein or lipid concentration producing a "space-occupying lesion" in serum water. Its presence and magnitude must be assessed in hyponatremic patients with, for example, paraproteinemia or hyperlipemic diabetic coma. In the absence of a direct-reading ion-selective electrode system, a method for measuring the water content of serum is required. We describe two rapid methods for measuring the diffusible water of serum: osmometry before and after dilution and chloride measurement before and after ultrafiltration. Either of these methods allows the true sodium status of a patient's serum to be determined.

Blood Chemical Analysis↗
PubMed1986

Clustering of serum calcium and magnesium concentrations in siblings.

Concentrations of both serum calcium, adjusted for albumin, and serum magnesium of siblings from 23 families were found to cluster around different concentrations within the normal reference interval. Variation between families accounted for 37% of the total variation in calcium and 28% of that in magnesium. A disturbance of serum calcium or magnesium homeostasis in an individual resulting in an altered serum concentration that remains within the reference interval might be recognized by examining values in siblings.

Adolescent↗
PubMed1985

Effects of aging on sex differences in psychomotor reminiscence and tracking proficiency.

The influence of aging on sex differences in psychomotor reminiscence and practice distribution effects was investigated in young (18 to 22 year) and elderly (57 to 86 year) participants within the context of reactive inhibition theory. As predicted by the theory in conjunction with hormonal considerations, aging eliminated the sex differences typically found in young adults, reduced the absolute amount of reminiscence, and diminished the gains in task proficiency arising from practice distribution, progressively so as practice increased. Significant age effects on task proficiency were detectable even within the age span of the elderly adults.

Adolescent↗