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Biomedical subjects

R E Chambers

Publications and source records attributed to R E Chambers.

34 records · Page 2Linked to original sources
PubMed1983

Quantitative radial immunodiffusion assay for serum amyloid A protein.

A radial immunodiffusion assay for serum amyloid A protein (SAA) using a commercially available antiserum is described. Serum is applied untreated to 1% agarose gels prepared in 0.02 M barbitone buffer, pH 8.6, containing 40 g/l polyethylene glycol 6000. Incubation is carried out overnight at 37 degrees C. The assay combines the advantages of simplicity, rapidity, specificity and stability, and avoids the hazards associated with the previously described radioimmunoassays. The method has sufficient sensitivity to measure SAA in the majority (99%) of normal subjects, and confirms the behaviour of SAA as a very sensitive acute phase reactant in inflammatory disease. The method is ideally suited to the rapid processing of a large number of samples.

Amyloid↗
PubMed1983

Serum amyloid-A protein concentration in rheumatoid arthritis and its role in monitoring disease activity.

The serum concentrations of serum amyloid-A protein (SAA), C-reactive protein (CRP), and alpha 1-acid glycoprotein (alpha 1-AGP) have been measured in 185 patients with rheumatoid arthritis. SAA and CRP concentrations correlated well (r = 0.86) both within and above the normal ranges, though SAA showed a greater incremental increase than CRP. All patients with normal SAA levels also had normal CRP and alpha 1-AGP concentrations. In contrast, in 40% of patients with normal CRP and alpha 1-AGP concentrations the SAA was raised, sometimes markedly so. The clinical and serological assessments of disease activity in these patients were not significantly different from those with concomitantly raised levels of CRP. These findings suggest that SAA is a more sensitive marker of inflammation than is CRP. The role of the measurement of SAA as a monitor for inflammatory disease activity is discussed.

Amyloid↗
PubMed1980

A comparison of urine free cortisol (RIA) with cortisol metabolites (GLC) for detecting increased cortisol secretion.

A comparison of the estimation of urine free cortisol by radioimmunoassay with the measurement of cortisol metabolites by gas-liquid chromatography (GLC) for detecting increased adrenal cortical activity has been made. Urine samples were examined from adults with normal or increased adrenal cortical function. Urine free cortisol showed a proportionately greater increase than cortisol metabolites when levels of cortisol were above twice normal, but both procedures led to the same qualitative conclusion about adrenal cortical activity. Their precision, ease of performance, assay time, and cost were similar. It is concluded that the greater sensitivity of the free cortisol does not warrant foregoing the additional information provided by the GLC method.

Adrenal Cortex↗
PubMed1979

Rapid assay for theophylline in clinical samples by reversed-phase high-performance liquid chromatography.

A fast, sensitive and highly specific method for the determination of theophylline in human serum is reported. Using a C18-bonded reversed-phase column with an acetonitrile-acetate buffer mobile phase theophylline is completely resolved not only from other dietary xanthines and their metabolites but also from co-administered drugs such as paracetamol and phenobarbitone. Use of beta-hydroxyethyltheophylline as internal standard allows a within batch precision of 2.0% and a between batch variation of 3.0%. Factors involved in the development of the method and its performance are discussed.

Asthma↗
PubMed1979

Theophylline estimation-a comparative evaluation of a gas chromatographic method and a high-performance liquid chromatographic method.

A comparative evaluation of a gas-liquid chromatographic (GLC) assay and a high-performance liquid chromatographic (HPLC) assay for the determination of plasma theophylline levels has been carried out. Both methods are reliable, accurate, and technically simple and appear to be specific for theophylline. The HPLC system is more sensitive (sample volume 25 micrliter) than the GLC system (sample volume 500 microliter) and is therefore suitable for the estimation of theophylline in microsamples. The HPLC system also has better precision (coefficient of variation: within-batch 2.0%, between-batch 3.0%) than the GLC system (coefficient of variation: within-batch 3.5%, between-batch 5.6%). Good correlation (r=0.964) was found between plasma theophylline levels (n=75, observed range 4-186 mumol/l) determined by each procedure. The results of this study indicate that, of the two systems investigated, HPLC is the method of choice.

Chromatography, Gas↗
PubMed1976

Comparison of a gas chromatographic and colorimetric method for the determination of plasma paracetamol.

Plasma paracetamol levels have generally been determined either by gas chromatography (Stewart and Willis, 1975), which relies on complex equipment, or by spectrophotometry (Knepil, 1974), which can be time-consuming. The introduction by Glynn and Kendal (1975) of a simple colorimetric method based on the reaction of paracetamol with nitrous acid to give 2-nitro-4-acetamidophenol appears to have overcome these disadvantages, thereby providing a suitable procedure for the rapid measurement of plasma paracetamol in cases of overdose. The method was reported to be specific for paracetamol, no interference being caused either by the sulphate and glucuronide conjugates of paracetamol or by a large number of other commonly found drugs. This communication presents the results of a study in which plasma paracetamol levels determined by the colorimetric method were compared with those determined by an established gas chromatographic technique.

Acetaminophen↗
PubMed1971

An assessment of methanolysis and other factors used in the analysis of carbohydrate-containing materials.

The stability of monosaccharides in methanolic hydrochloric acid of different strengths and at different temperatures was determined. They are generally stable for 24h in methanolic 1m- and 2m-hydrochloric acid at both 85 degrees C and 100 degrees C, but undergo considerable destruction in methanolic 4m- and 6m-hydrochloric acid at 100 degrees C. Analysis of glycopeptides and oligosaccharides of known composition showed that release of carbohydrate was complete within 3h in methanolic 1m-hydrochloric acid at 85 degrees C. Removal of methanolic hydrochloric acid by rotary evaporation resulted in considerable losses of monosaccharides, which could be prevented by prior neutralization. Methanolysis caused extensive de-N-acetylation of acetamidohexoses, so that a re-N-acetylation step is necessary in the analytical procedure. The addition of acetic anhydride for this purpose also prevented loss of internal standard by adsorption on the insoluble silver salts used in neutralization. Several trimethylsilylating agents were studied and suitable conditions are recommended. The effects on the analytical system of water and some common organic and inorganic contaminants are assessed.

Acetates↗