Biomedical subjects

S J Haswell

Publications and source records attributed to S J Haswell.

24 records · Page 2Linked to original sources

PubMed2000

Correlation between plasma total homocysteine and copper in patients with peripheral vascular disease.

BACKGROUND: Increased concentrations of both plasma total homocysteine and copper are separately associated with cardiovascular disease. Correlations between plasma total homocysteine, trace elements, and vitamins in patients with peripheral vascular disease have not been investigated. METHODS: The concentrations of trace elements in plasma were determined by the multielement analytical technique of total-reflection x-ray fluorescence spectrometry. Plasma total homocysteine was determined by HPLC. RESULTS: In the univariate and multivariate regression analyses, copper was positively correlated with plasma total homocysteine in all subjects (coefficient +/- SE, 0.347 +/- 0.113; P = 0.0026 and coefficient +/- SE, 0.422 +/- 0.108; P = 0.0002, respectively), and in patients with peripheral vascular disease (coefficient +/- SE, 0.370 +/- 0.150; P = 0.016; and coefficient +/- SE, 0.490 +/- 0.151; P = 0.0025, respectively). Correlation between copper and plasma total homocysteine was not detected in healthy control subjects. The concentration of calcium in plasma (67.5 vs 80. 8 microg/g) was significantly lower in the patients than in the control subjects (P = 0.02). When the patients were divided into groups, the patients with suprainguinal lesions had significantly higher copper concentrations (P = 0.04) and significantly lower selenium and calcium concentrations (P = 0.01 and 0.008, respectively) than the healthy subjects. Patients had higher concentrations of autoantibodies against oxidized LDL and concentrations of thiobarbituric acid-reactive substance than the healthy subjects (P <0.0001 and P = 0.001, respectively). The concentrations of plasma total homocysteine and alpha-tocopherol were significantly higher, and the concentrations of vitamin B(6) and beta-carotene were lower in the patients than the healthy subjects. CONCLUSION: Our findings suggest that the atherogenicity of homocysteine may be related to copper-dependent interactions.

Antioxidants↗

PubMed1999

Normal prion protein has an activity like that of superoxide dismutase.

We show here that mouse prion protein (PrP(C)) either as recombinant protein or immunoprecipitated from brain tissue has superoxide dismutase (SOD) activity. SOD activity was also associated with recombinant chicken PrP(C) confirming the evolutionary conserved phenotype suggested by sequence similarity. Acquisition of copper by PrP(C) during protein folding endowed SOD activity on the protein but the addition of copper following refolding did not. PrP(C) dependent SOD activity was abolished by deletion of the octapeptide-repeat region involved in copper binding. These results describe an enzymic function for PrP(C) consistent with its cellular distribution and suggest it has a direct role in cellular resistance to oxidative stress.

Animals↗

PubMed1995

Use of a model gut system to study the effects of dietary fibre and multivitamins on the speciation of copper, zinc and iron.

A gut model has been used to examine the speciation of three dietary available elements, Cu, Zn and Fe and their complexation with fibre and multivitamins. The analytical system consisted of an FI-ICP-MS interface for the determination of soluble and insoluble elemental distributions in samples. Solubility of elements was found to increase in the gut whereas in the intestinal tract they were seen to decrease. Experimental details are given for both the gut model and the speciation methodology used. The presence of fibre in the model had the greatest influence on elemental solubility in the intestinal tract whilst multivitamins have a less pronounced effect. The reduction in solubility of elements was most notable for zinc whilst the effect on iron and copper was notably less.

Copper↗

PubMed1992

Development and evaluation of analytical methodology for the determination of aflatoxins in palm kernels.

A rapid, simple and reproducible method for the simultaneous estimation of aflatoxins AFB1, AFB2, AFG1 and AFG2 in palm kernel samples has been developed by optimizing the sample preparation, solvent extraction, sample clean-up and quantification procedures. The aflatoxins are extracted from a slurried palm kernel sample with an acetone-water (80 + 20, v/v) mixture and the crude extract is cleaned up by solid-phase extraction using a phenyl bonded phase cartridge. The extract is passed through the cartridge with a water-methanol (93 + 7) mixture. Subsequent elution of the aflatoxins retained on the cartridge is achieved with a 3 ml aliquot of chloroform. The aflatoxin content of the eluate is quantified using a bi-directional high-performance thin-layer chromatography procedure. A critical evaluation of the proposed method was carried out by statistical comparison with the British Standard Method. The proposed procedure was shown to be more efficient and precise. Consistent recoveries of over 90% were achieved from spiked palm kernel extracts and detection limits were found to be 3.7, 2.5, 3.0 and 1.3 micrograms kg-1 for AFB1, AFB2, AFG1 and AFG2 aflatoxins, respectively.

Aflatoxins↗

PubMed1990

Analytical methodology for the determination of aflatoxins in peanut butter: comparison of high-performance thin-layer chromatographic, enzyme-linked immunosorbent assay and high-performance liquid chromatographic methods.

High-performance thin-layer chromatography (HPTLC) was applied to the separation and quantification of aflatoxin in 300 jars of "crunchy" peanut butter. A critical evaluation of the proposed HPTLC method has been carried out by statistical comparisons with a commercially available enzyme-linked immunosorbent assay (ELISA) kit and a high-performance liquid chromatographic (HPLC) method. The statistical tests indicated that whilst the distributions of the data sets obtained with each method were similar, the HPLC method was found to be biased. Over-all results indicated that the HPTLC method gave more consistent data, relatively lower standard deviations and lower coefficients of variation. The ELISA kit was found to be less precise than the HPTLC and HPLC methods and prone to some loss of sensitivity caused by matrix interference.

Aflatoxins↗

PubMedDate not supplied

The determination of mercury and selenium in maternal and neonatal scalp hair by inductively coupled plasma-mass spectrometry.

As part of a prospective study to evaluate maternal and neonatal scalp hair mineral profiles in normal and pathological pregnancy cases, the suitability of inductively coupled plasma-mass spectrometry (ICP-MS) was evaluated for the quantitation of mercury and selenium as part of a multi-element determination procedure. Treatment of hair samples included a closed-system microwave-assisted digestion in screw-capped PTFE vials of 10-mL capacity with concentrated nitric acid (2 mL) as the matrix solubilization medium. A digestion time of 10 min at 40% microwave power yielded limpid digestates, which, after appropriate dilution with deionized water to give a final acid concentration of 20% (v/v), were used for direct ICP-MS measurements within a rectilinear calibration range from 0 to 10 micrograms/L. Analytical recovery results for mercury ranged from 97 to 102%, whereas those for selenium ranged from 96 to 101%. Results from concurrent analyses of a human hair reference material showed a high degree of concordance with certified values. The results obtained suggest that the closed-system microwave-assisted digestion procedure described was effective in minimizing the risk of volatility-associated losses that can be encountered in the assays of both metals. The results also indicated that the ICP-MS system used in this study was suitable for including both metals as part of a multi-element quantitation procedure. Using this method, analytical results were obtained for mercury and selenium levels from 100 pairs of maternal and neonatal scalp hair samples collected at the postnatal ward of Hull Maternity Hospital, Hull, United Kingdom.

Female↗