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Biomedical subjects

I W Percy-Robb

Publications and source records attributed to I W Percy-Robb.

At least 55 records · Page 3Linked to original sources
PubMed1978

Investigations into the choice of immunogen, ligand, antiserum and assay conditions for the radioimmunoassay of conjugated cholic acid.

Investigations into the choice of immunogen, ligand, antiserum and assay conditions for the radioimmunoassay of conjugated cholic acid have been performed with a view to producing optimal assay conditions. Cholic acid-BSA was found to be the best immunogen to produce antibodies to conjugated cholic acid and the response was of an IgG type. Incorporating a spacer (hexanoic acid) between hapten and carrier protein resulted in a decrease in antiserum titre. Optimal conditions for the assay were found using [125I]histamine-glycocholic acid as ligand with a dilution of antiserum to produce 60% binding of ligand and a pH of 7.4. Using these assay conditions no serum effects were found; extraction of serum prior to assay was therefore unnecessary. The assay was sensitive enough to detect post-prandial increased in serum bile acid concentrations following a liquid test meal; no increase was observed throughout the same time period in a fasting control.

Antibody Specificity↗
PubMed1978

The peak monitor of the Technicon SMAC system.

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.

Autoanalysis↗
PubMed1977

Partial purification of two lithocholic acid-binding proteins from rat liver 100 000g supernatants.

1. The partial purification of two lithocholic acid-binding proteins from liver 100 000g supernatants is described. 2. Gel-filtration, (NH4)2SO4 fractionation, Ca3(PO4)2 fractionation and ion-exchange chromatography were used. 3. Both proteins exhibited glutathione S-transferase activity; one may be the non-specific anion-binding protein ligandin. 4. Glutathione S-transferase activity of one of the binding proteins was inhibited by lithocholic acid.

Animals↗
PubMed1977

An evaluation of ways of using equilibrium dialysis to quantify the binding of ligand to macromolecule.

1. The effect of systematic error (loss of ligand, complex or macromolecule) on three of the experimental designs by which equilibrium dialysis may be used to quantify the interaction of ligand and macromolecule is examined theoretically, and the design that is least sensitive to systematic error is identified. 2. Thirteen methods for fitting the binding isotherm to experimental data are compared by using them to analyse simulated data containing random error, and the most reliable method is identified.

Dialysis↗
PubMed1977

An assessment of a reflectance meter system for measurement of plasma or blood glucose in the clinic or side ward.

The Reflomat System for rapid estimation of plasma or blood glucose concentration has been evaluated. The System gave a linear response throughout its analytical range and the recovery of glucose added to glucose-free plasma was 97-105%. Addition of sodium fluoride to plasma produced a 7-15% reduction in the estimated glucose concentration. Plasma glucose concentration estimated with the Reflomat agreed closely with results of a glucose oxidase and a hexokinase based method, and blood glucose concentration measured with the Reflomat agreed well with results of a glucose oxidase method.

Blood Glucose↗
PubMed1977

Binding of bile acids by 100 000g supernatants from rat liver.

1. The binding of glycocholic acid, chenodeoxycholic acid and lithocholic acid to rat liver 1000 000g supernatants was studied by equilibrium dialysis. 2. The binding characteristics of the bile acids suggest that the binding components are involved in bile acid transport. 3. When mixtures of [14C]lithocholic acid and liver supernatants were eluted from columns of Sephadex G-75, a prominent peak of [14C]lithocholic acid appeared with proteins of mol.wt. approx. 40000. A second, smaller, peak of [14C]lithocholic acid was eluted with proteins of mol.wt. approx. 100000. 4. The inclusion of cholic acid, glycocholic acid or chenodeoxycholic acid in the eluting buffer decreased the amount of [14C]lithocholic acid that was eluted with the higher-molecular-weight component.

Animals↗
PubMed1976

A rapid method for the measurement of plasma glucose concentration.

A modification of the manual glucose oxidase-gum guaiacum method of Shipton, B., Wood, P.J. and Marks, V. ((1975) Med. Lab. Tech. 32,33), for use with plasma, is described. The method enables rapid measurement of plasma or serum glucose concentration between 1 and 22 mumol/1 using 10 mul of sample and a single colour reagent. Experience of the method in routine use has shown that the coefficient of variation, beteen batch, is 2.1% and the time taken for analysis of 1 sample, standards and a quality of control sample is 12 min (including centrifugation of blood to obtain plasma).

Blood Glucose↗
PubMed1976

Equilibrium-dialysis studies of the interaction between cholic acid and 100000g-supernatant preparations from the rat liver.

1. The binding of cholic acid to 100000g supernatants from rat livers was investigated by equilibrium dialysis and gel-exculsion chromatography. 2. Supernatants were found to contain at least two classes of binding site for cholic acid. 3. These recptor molecules are probably proteins since incubation with proteolytic enzymes resulted in complete loss of cholic acid binding. 4. Supernatants were added to columns of Sephadex G-75, and two groups of fractions were shown to bind cholic acid. One of these contained low-affinity binding sites and the other contained both low- and high-affinity binding sites. 5. Feeding cholestyramine had no effect on cholic acid binding. 6. Increased cholic acid binding occurred after injection of phenobarbitone. There was an increase in the amount of the low-affinity component but no change in the high-affinity component. 7. The dissociation constants of the binding of cholic acid suggest that the binding proteins may be involved in bile acid transport.

Animals↗
PubMed1973

Role of hepatic anion-binding protein in bromsulphthalein conjugation.

Using gel filtration, the binding of both glutathione and Bromsulphthalein (BSP) to a liver-soluble protein was found to be identical. BSP-conjugating activity (glutathione S-aryltransferase) was present only in the fractions corresponding to the two protein-bound markers. Using a highly sensitive assay, with 3,4-dichloronitrobenzene, the pattern of glutathione S-aryltransferase activity was found to coincide with Y protein. This evidence suggests that Y protein, or ligandin, has a dual role in hepatic transport: a specific enzymic function in the conjugation of certain anions with glutathione in addition to a transport function in the intracellular binding of organic anions.

Animals↗
PubMed1973

Two anti-anxiety drugs: a psychoneuroendocrine study.

Eight males were studied during 27 weeks, including two periods of five weeks during which they received clinical doses of sodium amylobarbitone and benzoctamine. Substitution of placebo for either drug caused raised anxiety and impairment of mental concentration. The drugs reduced restlessness during sleep and reduced paradoxical sleep. By the fifth week of sodium amylobarbitone, although sleep was still less restless in the early night it was more restless than normal in the late night.Blood samples were taken half-hourly during sleep by indwelling venous catheter. Plasma growth hormone concentration was little affected during drug administration but rose temporarily after withdrawal. There was a reduction of plasma corticosteroid concentration during sleep throughout administration of the drugs and a rebound above normal during the first withdrawal week.

Adrenal Cortex Hormones↗