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C J Seaborn

Publications and source records attributed to C J Seaborn.

13 recordsLinked to original sources
PubMed2001

Reproducibility of DXA: potential impact on serial measurements and misclassification of osteoporosis.

The reproducibility of bone mineral density (BMD) measurements by dual-energy X-ray absorptiometry (DXA), based on 12 successive monthly determinations, was assessed in a group of 24 subjects (23 postmenopausal women, 1 man) using six trained operators. The variability (S2A) was calculated from both duplicate operator measurements and the standard error of estimate from nonparametric regression of the individual subject series. Robust estimates of SA from the 90th percentile of the sampling distribution of variances were calculated for the spine (25 mg/cm2), femur neck (20 mg/cm2) and total femur (15.5 mg/cm2) using the bootstrap technique. The critical difference for a significant decrease (p = 0.05) at the spine, femoral neck and total femur was estimated at 57, 46 and 36 mg/cm2 respectively. Estimation of S2A allowed calculation of the probability that the true BMD, for an observed BMD near the osteoporosis diagnostic threshold (T-score < -2.5), is not misclassified. Analysis of covariance established a significant operator-subject interaction at all sites, but only the total femur was associated with a significant difference between operators. The percentage of body fat was a significant covariate for the spine and total femur regions. ANOVA showed that the greater proportion of variance was instrument-related. The limitations of DXA as an analytical method are discussed.

Absorptiometry, Photon↗
PubMed2000

Femur BMD bias associated with DPX-IQ reanalysis of DPX-acquired scan files.

Bone mineral density values calculated by DPX-IQ software reanalysis of original DPX software analyzed scans were compared at the femur region. Based on the results for 24 subjects each scanned on 12 different occasions, a significant bias at all sites--neck, Ward's triangle and trochanter--ranging from -0.7% (neck) to -2.1% (trochanter) was found. For the trochanter site 16 of the 24 subjects had significantly lower mean BMD values after DPX-IQ reanalysis, a trend also noted at the neck and Ward's triangle. Although it has been recommended that scans analyzed with DPX software do not require DPX-IQ reanalysis, our findings strongly indicate that DPX-IQ reanalysis is essential to minimize total error during follow-up BMD determinations.

Absorptiometry, Photon↗
PubMed1994

Assessment of a simple colorimetric procedure to determine smoking status in diabetic subjects.

The performance of a colorimetric assay for nicotine metabolites to validate self-reported smoking classification (nonsmoker, ex-smoker, and smoker) was assessed in a group of diabetic patients (n = 201). Comparison of the results with those of cotinine immunoassay (ELISA), by comparing respective areas under receiver operating characteristic curves, established the superiority of the cotinine immunoassay method. Adjusting the urinary concentrations of nicotine metabolites for creatinine excretion significantly lowered test performance. The sensitivity and specificity for the assay of nicotine metabolites to discriminate smoking classification within the diabetic patients at a threshold of > or = 28 mumol/L "cotinine carboxylic acid equivalents" were 68.4% and 98.6%, respectively; the corresponding sensitivity and specificity for urinary cotinine at a cutoff of > or = 0.5 mumol/L were 94.7% and 100%. The low sensitivity of the colorimetric urinary nicotine metabolites assay precludes its application as an objective assessment of smoking status in our patient population.

Adult↗
PubMed1993

Capillary blood glucose measurements in hospital inpatients using portable glucose meters.

BACKGROUND: The use of portable glucose meters by nursing staff to perform bedside capillary blood glucose measurements is standard practice in the management of diabetic hospital inpatients. Few studies, however, have examined the practical limitations or the cost of this technology. AIM: To investigate the performance and cost of capillary blood glucose measurements using portable glucose meters in a hospital inpatient population being managed for diabetes mellitus. METHODS: The setting was a 500 bed metropolitan University Teaching hospital, with 22 meters (Glucometer-M) in routine use by about 450 accredited nursing staff. The Glucometer-M was also compared with an operator-independent meter (Hemocue) to assess the effect of operator bias on the overall efficacy and cost of the programme. RESULTS: Retrospective analysis of Glucometer-M reagent strips and comparison of measurements (n = 72) with the Hemocue revealed a marked operator bias which diminished accuracy and increased costs. The significant proportion of low haematocrits (< 30%) in the hospital population limited the applicability of the Glucometer-M which only operates reliably over the haematocrit range 35-50%. The excess of blood glucose measurements was highlighted by both a hospital ward audit and the frequency which exceeded that of routine electrolyte assays. CONCLUSIONS: Reliable bedside estimation of capillary blood glucose levels in hospitals requires a meter which is accurate, has negligible operator bias, is largely unaffected by haematocrit, and has insignificant risk of cross-contamination. At present only the Hemocue fulfils these specifications. Irrespective of meter choice, it is necessary to develop criteria for glucose measurements and monitor adherence.

Australia↗
PubMed1989

Screening for microalbuminuria by use of a rapid, low-cost colorimetric assay.

We evaluated the pyrogallol red-molybdate(IV) method for quantification of urinary protein as a screening procedure for microalbuminuria by determining the assay's sensitivity and specificity at different concentrations of urinary albumin as measured by a comparison laser-nephelometric immunoassay. The pyrogallol red-molybdate(IV) method has sensitivity and specificity similar to that for other semiquantitative assays, but it is less expensive and sample throughput can be high if microtiter plate techniques are used.

Albuminuria↗
PubMed1988

Re-evaluation of the fructosamine reaction.

The difference in spectral characteristics between 1-deoxy-1-morpholinofructose (DMF) and protein/plasma samples in the fructosamine reaction has been related to the solubility of the diformazan formed by reduction of nitro blue tetrazolium chloride. Addition of the surfactant Triton X-100 (20 g/L) to the reagent buffer not only corrects this anomaly but also enhances the absolute response. Detailed investigation of DMF and dihydroxyacetone as calibration standards for the reaction established a clear preference for the latter. Fundamental differences in reaction kinetics were also noted between the Amadori rearrangement products of glucose formed from morpholine (DMF) or the amino lysine groups of protein (glycated albumin). From the reactivity of dihydroxyacetone, as well as glyceraldehyde, observed in the fructosamine reaction, and the presence of this class of compounds (trioses) in human plasma, we infer that they may also contribute to the differentiation of diabetic and non-diabetic samples.

Fructosamine↗