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Biomedical subjects

D McMaster

Publications and source records attributed to D McMaster.

At least 73 records · Page 4Linked to original sources
PubMed1991

The nickel content of certain commercially available metallic patch test materials and its relevance in nickel-sensitive subjects.

The nickel contamination of the metallic patch test substances from 3 commercial sources was estimated by atomic absorption spectrophotometry. Contamination was generally greatest in the cobalt patch test substances. To determine whether the levels of contamination encountered were sufficient to produce a false positive patch test, 20 nickel-sensitive patients were patch tested to various concentrations of free elemental nickel in aqueous solution. The level of nickel contamination was less than that required to produce a false positive patch test in our patients, but was at a level which could produce false positive reactions in subjects highly sensitive to nickel.

Adolescent↗
PubMed1991

Effect of blood transfusion on plasma selenium, glutathione peroxidase and manganese levels in very low birth weight infants.

Very low birth weight infants often receive multiple blood transfusions. We measured the plasma levels of the trace elements selenium, manganese, and glutathione peroxidase in 20 very low birth weight infants prior to blood transfusion and then at 24, 48 and 72 h after transfusion. There was no detectable change in mean selenium or glutathione peroxidase concentrations after transfusion, but the mean (SD) plasma manganese increased from 3.8 (1.5) to 6.0 (2.3) micrograms/l at 72 h.

Blood Transfusion↗
PubMed1990

Determination of selenium in blood plasma and serum by flow injection hydride generation atomic absorption spectrometry.

A flow injection hydride generation atomic absorption spectrometric (AAS) method has been used to determine the selenium concentrations of human serum and plasma samples following digestion with nitric, sulphuric and perchloric acids. In the hydride generation process, reduction was carried out by sodium tetrahydroborate to produce a hydride that was atomized in a flame-heated atomisation cell. The method had a detection limit of 1.2 ng ml-1 and a sensitivity of 2.1 ng ml-1. Within-run precisions of 5.8% at 20 ng ml-1 and 4.5% at 80 ng ml-1, and between-run precisions of 4.8% at 69 ng ml-1 and 3.4% at 80 ng ml-1 were obtained. An inter-laboratory comparison study with a graphite furnace AAS method was carried out and the results showed excellent agreement. The flow injection method of sample introduction allowed the use of a sample volume of 330 microliters with an injection rate of 90 injections per hour.

Borohydrides↗
PubMed1990

Potentially life-threatening cardiac dysrhythmia in a child with selenium deficiency and phenylketonuria.

Selenium deficiency is a frequent finding in children with phenylketonuria (PKU) receiving dietary treatment. We report the occurrence of episodic ventricular tachycardia in a 9-month-old infant with PKU. Serum selenium (Se), 0.13 mumol/l (normal range 0.28-1.12 mumol/l, mean +/- 2 SD), and whole blood glutathione peroxidase (GSHPX), 16 U/g Hb (normal range 19.5-34.3 U/g Hb, mean +/- 2 SD), were low. Auscultation of cardiac rhythm is recommended during the routine follow-up of young children with PKU. Se deficiency should be considered in the aetiology of a dysrhythmia and corrected with Se supplementation.

Diet Therapy↗
PubMed1990

Glutathione peroxidase and selenium levels in the preterm infant.

Glutathione peroxidase (GPX) and selenium are important in the prevention of cellular oxidant damage. Whole-blood GPX and plasma selenium were measured at birth and sequentially afterwards in 75 preterm babies. GPX activity at birth was 2.74 +/- 0.08 (mean +/- SEM) U/ml. Mean GPX activity remained relatively unchanged for up to 70 days postnatal age. Plasma selenium at birth was 0.43 +/- 0.02 (mean +/- SEM) mumol/l), decreasing to low levels by 10 weeks postnatal age. Neither GPX activity nor plasma selenium was related to birth weight, gestational age or infant sex.

Age Factors↗
PubMed1990

Sources of fat in the northern Irish diet.

The Belfast MONICA Project carried out the joint European Economic Community WHO MONICA Project nutrition study (EURONUT) in 1985-1986 in 401 males subjects (45-64 years) using 3-day weighed records. This resulted in 356 reliable records which were analysed. The mean energy intake was 2369 Kcals (9.9 MJ) with 38% of energy (including alcohol) derived from fat (16.5% from saturated fat, 14.0% from monounsaturated fat, 4.8% from polyunsaturated fat), 14.2% from protein, 43.2% from carbohydrate and 4.0% from alcohol. The mean total fat was 100.3 g (saturated fat 43.5 g, monounsaturated fat 36.9 g, polyunsaturated fat 12.5 g), with a P:S ratio of 0.32. The sources of the different kinds of fat and cholesterol are presented as cumulative percentages of the total. This is a useful way of identifying those foods which contribute chiefly to fat in the diet, and it should have important implications for the monitoring of progress towards meeting dietary guidelines.

Cholesterol, Dietary↗
PubMed1990

Automated measurement of two indicators of human selenium status, and applicability to population studies.

We developed an automated system consisting of a centrifugal analyzer and an atomic absorption spectrophotometer with Zeeman background correction to produce a profile of the concentrations of selenium and the selenium-dependent enzyme glutathione peroxidase (EC 1.11.1.9) in serum and whole blood, for use in epidemiological surveys in Northern Ireland. No pretreatment of samples other than dilution is required, and at least 35 subjects can be screened within 24 h of venesection. For selenium in serum the between-run CV was 5.7% and 4.4% within run. For selenium in whole blood the CV was 5.9% between runs, 5.7% within run. The within-run CV for glutathione peroxidase was 0.92% for serum, 1.18% for blood; the between-run CV was 8.3% for serum. To illustrate the use of the system, we present the profile of selenium and glutathione peroxidase in serum and whole blood from 100 adults 25 to 64 years old.

Adult↗
PubMed1989

Coronary risk factor prevalence in a high incidence area: results from the Belfast MONICA Project.

Northern Ireland remains at the top of the world mortality league for ischaemic heart disease. The Province is providing a centre for the World Health Organisation's MONICA Project. Registration of coronary heart disease events began in 1983 and the first of three population surveys took place in 1983-4. A total of 2,361 men and women aged 25-64 years was screened. Subjects were shorter and heavier than their fellow citizens in Great Britain. The estimated mean cholesterol levels in the 25-64-year-old population (5.80 mmol/l in males and 5.85 mmol/l in females) were similar to those reported from Great Britain. Although mean systolic blood pressures were lower, mild diastolic hypertension was considerably more common; cigarette smoking levels were similar. The results were consistent with those expected for an area with a high coronary heart disease mortality, with more than 80% of subjects being at increased risk in terms of the three major factors (cigarette smoking, hypertension and raised cholesterol). Public concern about coronary heart disease has grown and recently the Department of Health and Social Services (NI) has launched a 10-year prevention programme which will primarily employ a population approach.

Adult↗
PubMed1988

Functional receptors for fish neuropeptide urotensin II in major rat arteries.

Receptor binding of fish neuropeptide urotensin II (UII) was characterized in membranes isolated from major rat arteries. Monoiodinated UII radioligand (125I-UII) was prepared and purified using high-pressure liquid chromatography (HPLC). The contractile potency of iodinated UII (I-UII) on rat thoracic aorta strips was somewhat lower than that of native UII. The binding of 125I-UII to the membrane preparations of rat thoracic aorta was saturable, specific and time-dependent. Scatchard analysis indicated a single population of binding sites with an apparent dissociation constant of 5.9 x 10(-9) M. The calculated maximal number of binding sites was about 155 fmol/mg protein. The specific binding to the membrane preparations from the abdominal aorta and mesenteric artery was about 27 and 8%, respectively, of those in the thoracic aorta, which corresponds to the order of contractile potency of UII on rat blood vessels: thoracic aorta greater than abdominal aorta greater than mesenteric artery. The displacement of 125I-UII binding by the UII peptide or its fragments (UII-(5-12), UII-(6-12) and UII-(6-11] were also comparable to their contractile effects on rat thoracic aorta strips (UII greater than UII-(5-12) greater than UII-(6-12) much greater than UII-(6-11]. These results suggest that the fish neuropeptide, UII, can induce contraction of rat vascular tissue by interacting with its functional receptors.

Animals↗
PubMed1988

The growth-associated neuronal phosphoprotein B-50: improved purification, partial primary structure, and characterization and localization of proteolysis products.

A reversed phase HPLC procedure is reported that has allowed the separation of the growth-associated, kinase C substrate protein B-50 [previously purified by isoelectric focussing (IEF)] into three components (1-, m- and rB-50). The minor form 1B-50 (probably a proteolysis product) gave a 24-residue N-terminal amino acid sequence, but the major and possibly native form (mB-50) (and also rB-50 which is probably formed during IEF) appeared to be N-terminally blocked. HPLC also separated B-60, the major proteolysis product of B-50, into three components, and the N-terminal sequence of the major B-60 was determined. HPLC peptide mapping of SAP digests of the various B-50 and B-60 protein confirmed their close relationship, and four SAP generated fragments also afforded sequence data. The amino acid sequences obtained (1B-50, B-60 and fragments) are all found in the recently predicted (based on nucleotide sequencing) B-50/GAP43 sequence (226 amino acids), further confirming the identity of B-50 and GAP43, and helping clarify the relationship of B-60 (starting at position 41 of the predicted sequence) to B-50. Correlation of amino acid analyses, SAP fragment data, and the predicted sequence provided additional information on the length of the translated products, including evidence that the N-terminus of the major (blocked) form of B-50 starts at position 1 (Met) of the predicted sequence.

Animals↗
PubMed1988

Factors influencing total cholesterol and high-density lipoprotein cholesterol concentrations in a population at high coronary risk.

Serum total cholesterol and high-density lipoprotein (HDL) cholesterol concentrations were measured in 1122 men and 1147 women aged between 25 and 64 years during the first Belfast MONICA survey, and the results subjected to multiple regression analysis. In both men and women, total cholesterol increased with age. Although HDL-cholesterol showed little variation with age, the values were considerably higher in women than men. Total cholesterol increased with body mass index while HDL-cholesterol decreased, and these findings persisted after adjustment for age. Regular exercise was associated with higher HDL-cholesterol values, even after adjustment for age and body mass index. Among men and women who abstained from alcohol, lower values of HDL-cholesterol were observed. In both sexes, cigarette smoking was associated with significant increases in total cholesterol values and decreases in HDL-cholesterol values, though some of these findings became apparent only after adjustment for other relevant factors. Perhaps surprisingly, a measure of health knowledge showed no association with blood lipid concentrations.

Adult↗
PubMed1987

Urotensin I-like immunoreactivity in amacrine cells of the goldfish retina.

Urotensin I-like immunoreactivity (UILI), in different localization from that of corticotropin releasing factor-like immunoreactivity (CRFLI), in the goldfish retina has been demonstrated by means of radioimmunoassay, high-performance liquid chromatography (HPLC) and immunohistochemistry. Radioimmunoassay showed 350 +/- 40 pg/mg prot. of UILI in goldfish retina extracts. The immunoreactive material present in the retina was also characterized by reversed phase HPLC. Some of the UILI co-eluted with synthetic carp UI, though the HPLC experiments suggested the existence of other UILI substance(s) with less hydrophobicity than synthetic UI. By immunohistochemistry, UILI and CRFLI were seen in different amacrine cells of the goldfish retina. It is suggested that UI may be involved in the fish visual transmission system together with CRF and other neuropeptides.

Animals↗
PubMed1987

The effect of auranofin on glucose uptake by the isolated vascularly perfused, small intestine of the rat.

Auranofin at a concentration of 2.5 micrograms/ml had no effect on glucose uptake by the viable, isolated, vascularly perfused, small intestine of the rat and no net movement of water was detected. No effect on glucose uptake or water movement was found when intestines from rats fed 0.1 mg/Kg body weight per day for 4 weeks were perfused with drug free medium. Mucosal damage was seen in 1 of 2 rats fed Auranofin and examined histologically.

Administration, Oral↗
PubMed1986

Radioimmunoassays for fish tail neuropeptides: II. Development of a specific and sensitive assay for and the occurrence of immunoreactive urotensin II in the central nervous system and blood of Catostomus commersoni.

A sensitive radioimmunoassay (RIA) based on an antiserum to synthetic Gillichthys mirabilis urotensin II (UII) generated in rabbits, reacting with all known forms of the UII peptides, was developed. The UII was iodinated by either the chloramine-T or the lodogen method and was purified by high-pressure liquid chromatography. The antiserum, at a final dilution of 1:125,000, gave 50% binding of the iodinated UII. The sensitivity of the RIA was 1.8 +/- 0.2 pg/assay tube (1.2 +/- 0.2 fmol/tube; n = 7). Crossreactivity studies with various UII peptides, modified UII peptides, and fragments indicated that the immunoreactive recognition site of this antiserum is directed to the disulfide ring region (positions 6-11) of the UII peptides. Somatostatin 14, which has the part sequence 7-9 in common with UII peptides, did not crossreact. No detectable crossreactivity with urotensin I, urophysin B or D from Catostomus commersoni, arginine vasopressin, or arginine vasotocin could be shown. Displacement curves obtained with standard extracts of G. mirabilus urophyses were similar to those of synthetic G. mirabilus UII. comparison of RIA and bioassay of G. mirabilis urophysial extracts showed good correlation. Immunoreactive UII was detected in different parts of the brain, spinal cord, and blood of C. commersoni.

Animals↗
PubMed1986

Treatment of nickel dermatitis with Trientine.

23 nickel-sensitive patients with hand eczema were treated with Trientine 300 mg daily and a placebo in a double-blind, crossover trial. No significant improvement occurred in the hand eczema. A surprising finding was that there was no detectable increase in urinary nickel excretion, in contrast to animal studies.

Adult↗
PubMed1986

Glutathione peroxidase activity in cord blood: effects of fetal sex and maternal smoking.

Glutathione peroxidase activity was estimated in the cord blood of 47 newborn infants. In 23 cases corresponding maternal glutathione peroxidase activities were measured at time of delivery and compared with 23 non-pregnant women of the same age. Mean cord blood activity was 23.6 +/- 4.8 IU/g Hb at 37 degrees C. Maternal smoking and male fetal sex were associated with significantly lower fetal glutathione peroxidase activity. Maternal levels (33.0 +/- 5.0 IU/g Hb) were significantly higher than those in cord blood (p less than 0.001) but were the same as those for non-pregnant women. Maternal to cord blood level ratio was 1.5:1.

Female↗