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Biomedical subjects

J R McMurray

Publications and source records attributed to J R McMurray.

9 recordsLinked to original sources
PubMed1999

Hypophosphataemia in general practice patients.

We compared plasma phosphate concentrations in general practice patients and hospital inpatients and outpatients over an 8-month period. The distribution of results in all three groups was similar and 12-16% of results were at or below 0.8 mmol/L. In general practice patients, 8.3% of results from males and 12.1% from females were below the lower limit of their respective reference ranges. Eighteen of these patients (0.2% of results) had plasma phosphate concentrations < or = 0.4 mmol/L. On follow-up, only two of these patients had any attributable cause for their severe hypophosphataemia; in the remainder, it was unexpected and unexplained. Hypophosphataemia in outpatients and general practice patients is more common than has previously been appreciated. We present a strategy for further investigation of these patients.

Adult↗
PubMed1997

Urinary excretion of albumin and retinol binding protein in systemic lupus erythematosus.

We have measured the urinary excretion of total protein, albumin and retinol binding protein (RBP) in random urine specimens obtained from 40 female patients with systemic lupus erythematosus (SLE). Thirty-three of these patients had no clinical evidence of any renal impairment (non-renal SLE); seven had overt renal disease (renal SLE). RBP:creatinine ratios were significantly higher in non-renal SLE patients compared with female controls (P = 0.002). There was no significant difference between urine total protein concentrations, albumin:creatinine or total protein:creatinine ratios in non-renal SLE patients when compared with controls, despite approximately 20% of these patients having elevated excretion of total protein or albumin. All seven renal SLE patients had elevated albumin:creatinine ratios but only four of them had an increased RBP:creatinine ratio. Of 29 non-renal SLE patients who had urinary total protein concentrations below 0.2 g/L, (i.e. approximating to a negative protein dipstick), 14 had increases in either albumin or RBP:creatinine ratios. Only two patients had increases in both. In the absence of clinical evidence of renal disease, increases in urinary albumin or RBP excretion could indicate subclinical nephropathy and measurements may have a role in the early diagnosis and subsequent monitoring of renal disease in SLE.

Adult↗
PubMed1995

Evaluation of a second-generation electrochemical blood glucose monitoring system.

One hundred and ninety-five diabetic patients attending hospital clinics gave blood samples to test the accuracy and precision of a second generation glucose sensor (satellite G, MediSense Inc., Abingdon, UK) with particular emphasis on its performance with venous blood. Sensor results correlated closely with a standard laboratory method; analysis of residuals showed no deviation from zero slope. Mean percentage difference was low (< +/- 6.0%) and the 95% limits of agreement were < +/- 30% with both capillary and venous blood. Error Grid Analysis showed that none of the measurements would have led to serious management errors. Precision of the system was good with coefficients of variation (CV) between 2.8% and 7.1% for glucose concentrations ranging from 3.0 to 24.0 mmol l-1. The mean CV for duplicate measurements was 5.4% with capillary and 4.4% with venous blood. We conclude that the electrochemical glucose method gives accurate and precise measurements of venous and capillary blood glucose.

Analysis of Variance↗
PubMed1993

Urinary retinol binding protein: stability and pre-analytical handling of specimens for its measurement.

The stability of retinol binding protein (RBP) in urine has been reassessed and was found to be pH-dependent, diminishing as urinary pH decreased. When urines were incubated at 4 degrees C for 1 week, statistically significant losses of RBP were observed at pH values less than seven, varying in degree in different urines. At 37 degrees C some urine specimens showed minor losses when incubated for periods up to 4 h. This was more marked at pH 5 than pH 7 with maximum losses of 26% and 12%, respectively. When adjusted to pH 7, urines showed no significant loss of RBP when stored at 4 degrees C for up to 2 weeks; at -20 degrees C no significant change in RBP concentration was found for at least 14 weeks. To minimize losses of RBP it is recommended that urine pH is adjusted to above seven immediately after voiding.

Enzyme-Linked Immunosorbent Assay↗
PubMed1991

Simple, optimized liquid-chromatographic method for measuring total hydroxyproline in urine evaluated.

We have optimized a method for measuring total hydroxyproline (HYP) in urine by HPLC after release from urinary peptides by solid-phase hydrolysis on Dowex 50W x 8 ion-exchange resin. The HYP was derivatized with 4-chlor-7-nitrobenzo-2-oxa-1,3-diazole, and excess reagent was removed with the use of a 100-mg C18 Bond-Elut cartridge. The HYP derivative was separated isocratically at 30 degrees C on a 250 x 4.6 mm reversed-phase column containing 5-microns particles of Spherisorb S5 ODS-2, with S-carboxymethylcysteine as internal standard. Total assay time was 14 min. The standard curve for the method was linear from the detection limit for HYP, 3.6 mumol/L, to 10 mmol/L. The between-batch CV was less than 5.1% and the mean analytical recovery of HYP was 95% +/- 1.4%. Comparison with a commercially available colorimetric method showed good correlation: y = 1.158x + 19.76 mumol/L (Syx = 74, n = 120), but HPLC results were 15% higher, probably from incomplete hydrolysis with the colorimetric method. This method offers a considerable improvement in assay time, specificity, sensitivity, precision, and cost compared with the colorimetric method.

Chromatography, High Pressure Liquid↗
PubMed1985

Evaluation of the measurement of blood glucose levels on dried filter paper blood spots.

The measurement of blood glucose using discs punched from dried spots on filter paper has been examined as a method to monitor patients' home blood glucose results. We confirm that the method is precise, reproducible, and accurate, but show that impregnation of the filter paper with boric acid leads to an initial false elevation in measured glucose levels and does not improve stability of the sample more than does refrigeration. Degradation of blood glucose is insignificant over 28 days if samples are stored at -20 degrees C, and samples kept at 4 degrees C show minimal falls provided they are analysed within 7 days. The greatest breakdown of glucose was shown to occur during the first 48 hours after application. The filter paper glucose measurements correlated closely with parallel measurements using a Yellow Springs Glucose Analyser.

Blood Glucose↗
PubMedDate not supplied

Gender and the clinical usefulness of the albumin: creatinine ratio.

One hundred and eighty-seven diabetic and 105 control subjects collected timed overnight urine samples to measure the inter-individual variation in creatinine excretion rate and its determinants, and to test the relationship between albumin excretion rate (AER) and two 'surrogate measures', the albumin concentration and albumin:creatinine ratio. Creatinine excretion was 55% higher in men than women (geometric mean 8.9 mumol min-1 (95% confidence limits 4.7-17.0) compared with 5.7 (3.0-10.9); p < 0.001). Gender accounted for 31% of the variation in creatinine excretion and body mass index 1.4%; neither age nor the diabetic state had a significant effect. The relationships between AER and the two surrogate measures differed between diabetic subjects and controls such that relationships constructed from non-diabetic data would not hold true for diabetes. Likewise, the relationship between AER and albumin:creatinine ratio differed between men and women such that a ratio of 4.0 mg mmol-1 corresponded to a predicted AER of 35 micrograms min-1 in men and 23 micrograms min-1 in women. The albumin:creatinine ratio outperformed albumin concentration in terms of sensitivity and specificity and its performance was better in women than men. We conclude that the albumin:creatinine ratio is a better surrogate for AER than albumin concentration. If 'action levels' are to be defined for screening programmes, they should be derived from diabetic and not non-diabetic data and should be different in men and women. We propose a direct rather than screening role for the albumin:creatinine ratio in the management of diabetic nephropathy.

Adult↗