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Biomedical subjects

D McMaster

Publications and source records attributed to D McMaster.

At least 55 records · Page 3Linked to original sources
PubMed1996

Long-lasting allergic patch test reactions to nickel sulfate: analysis by nickel quantification and immunocytochemistry.

We previously showed the median duration of positive patch test reactions to nickel sulfate (5% pet.) was 9 days, and defined as long-lasting (LLAPTR) the 14.3% of reactions that persisted for 17 days or longer. The pathomechanisms of LLAPTR are unclear, but may involve either localized antigen persistence or abnormal downregulation of the cellular immune response. In this study, we compared (a) the nickel concentration and (b) the immunocytochemical nature of the local immune reaction, between biopsies from LLAPTR (n = 8) and normally resolving allergic patch test reactions (NRAPTR) (n = 8) to nickel sulfate. The concentration of nickel in LLAPTR (median 0.56 microgram/g, range 0.25-3.87 micrograms/g, mean 0.83 microgram/g, 95% CI 0.35-1.31) and NRAPTR (median 0.58 microgram/g, range 0.2-1.85 micrograms/g, mean 0.88 microgram/g, 95% CI 0.02-1.74) was similar. Activated T lymphocytes, expressing surface IL-2 receptor, HLA DR, DR alpha 1, DP, DQ, and CD2 > CD8 > CD4 antigens, were seen throughout the dermis and occasionally infiltrating the suprabasal layer of the epidermis in all biopsies. CD1 and HLA DR, DR alpha 1, DP, and DQ-expressing Langerhans cells were present throughout the epidermis and occasionally seen in the papillary dermis. HLA DR, DR alpha 1, DP, and DQ antigen expression were also seen on the surface of non-dendritic cells in the epidermis (probably either keratinocytes or T lymphocytes) and vascular endothelial cells in the papillary dermis. There were no significant qualitative or quantitative differences in the immunocytochemical nature of the localized immune reaction between LLAPTR and NRAPTR. These findings suggest that the pathomechanism of LLAPTR to nickel sulfate is unlikely to be explained simply on the basis of nickel concentration or the nature of the localized immune reaction at the patch test site.

Adult↗
PubMed1996

Preliminary results from follow-up of a large-scale population survey of antibodies to gliadin, reticulin and endomysium.

UNLABELLED: Coeliac disease is often under-diagnosed, particularly in cases which are atypical or asymptomatic. OBJECTIVE: The aim of this study was to comprehensively assess the prevalence and clinical profile of adult coeliac disease in our community. METHODS: One-hundred-and-thirteen subjects from the most recent MONICA (multinational MONItoring of trends and determinants in CArdiovascular disease)1991/2 survey with positive serology were followed up 3 years after initial screening and assessed by means of (i) a clinical questionnaire, (ii) screening blood tests, and (iii) jejunal biopsy. RESULTS: Forty-six subjects (21 male, mean age 51 years) have been followed up to date. Prior to follow-up, two of these subjects were diagnosed as having coeliac disease. Ten (3 male, mean age 51 years) of 44 subjects had enteropathy. Three of these 10 subjects were relatively asymptomatic, 3 had folate deficiency and 3 had iron deficiency. Thus 12 of the 1823 initially screened had enteropathy consistent with coeliac disease. CONCLUSIONS: Coeliac disease is more prevalent than previous estimations and was found to be at least 1 in 152.

Adult↗
PubMed1996

Tolerance of mixed lipid emulsion in neonates: effect of concentration.

AIMS: To compare the effect of concentration of a mixed lipid emulsion (50:50 medium chain triglyceride/long chain triglyceride) (MCT/LCT) on lipid tolerance in neonates. METHODS: A prospective randomised controlled trial of 75 neonates requiring prolonged parenteral nutrition was conducted in the neonatal intensive care units of the Royal Maternity Hospital, Belfast, and the Waveney Hospital, Ballymena. Thirty eight infants received 10% and 37 20% lipid emulsion. Infants were randomly assigned to groups at the start of parenteral nutrition and studied if they required seven or more days of this. Lipid tolerance was assessed by twice weekly measurements of plasma triglyceride and cholesterol concentrations and weekly measurement of non-esterified fatty acids and beta hydroxy butyrate. Anthropometry was carried out weekly. RESULTS: The mean cholesterol in the 10% group was significantly higher within the first seven days of the study compared with the 20% group (3.5 vs 2.87 mmol/l), and continued to rise over the study period in contrast to the 20% group. A similar pattern was observed with the triglyceride concentrations. There was no significant difference in non-esterified fatty acids, beta hydroxy butyrate, or growth between the two groups. CONCLUSION: Sick neonates show better biochemical tolerance to 20% MCT/LCT emulsion than to 10% emulsion.

Cholesterol↗
PubMed1995

Selenium dependent glutathione peroxidase activity in human follicular fluid.

The purpose of this study was to evaluate the follicular fluid selenium status of in vitro fertilization patients in relation to their individual characteristics and treatment outcome. A total of 135 samples of follicular fluid were collected from 112 patients during transvaginal oocyte retrieval. Selenium levels and glutathione peroxidase (GSHPx) activity were measured in follicular fluid (FF) and blood serum. A selenium dependent GSHPx activity in follicular fluid has been demonstrated. Patients with unexplained infertility had significantly decreased follicular selenium levels as compared with those with tubal infertility or male factor. The mean GSHPx activity in follicles yielding oocytes which were subsequently fertilized exceeded that of the follicles with non-fertilized oocytes. Tobacco smoking resulted in significantly diminished follicular GSHPx activity. The Se/GSHPx pattern of the FF seems to be significant for the evaluation of the follicular milieu.

Adult↗
PubMed1995

The effects of desferrioxamine and ascorbate on oxidative stress in the streptozotocin diabetic rat.

Oxidative stress and protein glycation are closely related processes that may contribute to the development of complications in diabetes mellitus. Treatment with antioxidants could protect against these processes at a biochemical level, and we have therefore investigated the effects of ascorbate and desferrioxamine treatment in the streptozotocin diabetic rat. Diabetic animals were given ascorbate 1 g/l in drinking water or desferrioxamine 6 mg/kg/day by subcutaneous injection and were killed after 6 weeks. In diabetic animals, oxidative stress was increased as shown by increased levels of conjugated dienes (CD) in plasma and malondialdehyde (MDA) in plasma, erythrocyte membranes, and urine. In addition, there was depletion of the nutritional antioxidants ascorbate, alpha-tocopherol, and retinol. Insulin treatment returned all of these parameters to normal. Ascorbate supplementation or desferrioxamine treatment alone failed to reduce oxidative stress, but a combination of both interventions restored MDA, CD, and antioxidant vitamins to control values. Both ascorbate and desferrioxamine also reduced HbA1c and glycated albumin levels. Treatment with antioxidants can reduce both oxidative stress and protein glycation and may help to reduce the risk of developing diabetic complications. However, ascorbate can have both prooxidant and antioxidant effects in vivo, and its use in pharmacological doses should be approached with caution.

Animals↗
PubMed1995

Autres pays, autres coeurs? Dietary patterns, risk factors and ischaemic heart disease in Belfast and Toulouse.

The WHO MONICA project monitors trends and determinants in cardiovascular disease to relate classical risk factor changes to trends in incidence rates. The Belfast and Toulouse MONICA centres have also collaborated in dietary studies. Both centres have validated incidence and attack rates for ischaemic heart disease using coronary event registration. These data confirm that the disease in middle-aged men is between three and four times as common in Belfast as in Toulouse. Risk factor surveys show some differences between the centres, but the overall risks assessed by two multiple logistic function scoring systems were identical. A weighed dietary survey revealed no important difference in macronutrient intake, although carbohydrate and saturated fat intake in Belfast was significantly higher. Protein, dietary cholesterol and polyunsaturated fat, particularly linoleic acid intake, was significantly higher in Toulouse, as was consumption of wine, cheese, fruit and vegetables, but not potatoes. The Northern Irish diet is typically Northern European, but although the diet in Toulouse has some features of the Mediterranean diet, it is not appreciably different from that in Belfast in terms of total fat intake. Major differences are present for several food items, and in general these differences add support to the antioxidant hypothesis.

Antioxidants↗
PubMed1995

The effect of diet on lipid, apoprotein and lipoparticle variation in the ECTIM study in Belfast.

The objective of the study was to evaluate the contribution of dietary factors to variation of plasma levels of lipids, apoproteins and lipoparticles in the Northern Ireland population. This study was part of a larger case-control study of the genetic and environmental determinants of myocardial infarction in France and Northern Ireland. A random sample of 175 middle aged men was drawn from the population covered by the Belfast MONICA project register. Habitual diet was assessed by a questionnaire. A blood sample was obtained after an over-night fast for determination of plasma levels of lipids, apoproteins and lipoparticles. All participants had a medical examination and completed a lifestyle questionnaire. In a stepwise regression, after adjusting for co-factors (i) vitamin C and (ii) alcohol consumption were the only nutrients which contributed significantly to the variation in, respectively, (i) Total Cholesterol, LDL Cholesterol and Apolipoprotein B (inverse correlation) and (ii) HDL Cholesterol and LpAI (positive correlation). The amount of variation explained by the final models was modest, ranging from 4% to 15%. In conclusion, in this Northern Ireland population, habitual diet contributes to little of the variation in plasma levels of lipids, apoproteins and lipoparticles.

Adult↗
PubMed1994

Antioxidant status and lipid peroxidation in hereditary haemochromatosis.

Hereditary haemochromatosis is characterised by iron overload that may lead to tissue damage. Free iron is a potent promoter of hydroxyl radical formation that can cause increased lipid peroxidation and depletion of chain-breaking antioxidants. We have therefore assessed lipid peroxidation and antioxidant status in 15 subjects with hereditary haemochromatosis and age/sex matched controls. Subjects with haemochromatosis had increased serum iron (24.8 (19.1-30.5) vs. 17.8 (16.1-19.5) mumol/l, p = 0.021) and % saturation (51.8 (42.0-61.6) vs. 38.1 (32.8-44.0), p = 0.025). Thiobarbituric acid reactive substances (TBARS), a marker of lipid peroxidation, were increased in haemochromatosis (0.59 (0.48-0.70) vs. 0.46 (0.21-0.71) mumol/l, p = 0.045), and there were decreased levels of the chain-breaking antioxidants alpha-tocopherol (5.91 (5.17-6.60) vs. 7.24 (6.49-7.80) mumol/mmol cholesterol, p = 0.001), ascorbate (51.3 (33.7-69.0) vs. 89.1 (65.3-112.9), p = 0.013), and retinol (1.78 (1.46-2.10) vs. 2.46 (2.22-2.70) mumol/l, p = 0.001). Patients with hereditary haemochromatosis have reduced levels of antioxidant vitamins, and nutritional antioxidant supplementation may represent a novel approach to preventing tissue damage. However, the use of vitamin C may be deleterious in this setting as ascorbate can have prooxidant effects in the presence of iron overload.

Adult↗
PubMed1994

RU 486: an alternative to surgical abortion.

After 5 years of use in more than 100,000 European women, RU 486, an antiprogestin medication used as a medical abortifacient, has recently come under scrutiny in the United States. This article discusses the current and potential uses of RU 486. Also addressed are the history, advantages, and disadvantages of medical abortion (including the acceptability of the method from a woman-centered perspective); new clinical trials; and ethical issues.

Abortion, Induced↗
PubMed1994

Normal red cell magnesium concentrations and magnesium loading tests in patients with chronic fatigue syndrome.

Red blood cell magnesium concentrations were measured in samples from 89 patients who fulfilled the diagnostic criteria for chronic fatigue syndrome and the results compared to those found in an age and sex matched group selected from the normal population. No significant difference was found. Six patients were further investigated using a magnesium loading test to determine if there was any evidence of magnesium deficiency associated with this disorder. None was found. There is therefore no indication for the use of magnesium therapy in the management of this condition.

Adult↗
PubMed1994

Oxidative stress in haemodialysis.

Patients with chronic renal failure, including those receiving regular long-term haemodialysis, have a high incidence of premature cardiovascular disease. Oxidative stress, which occurs when there is excessive free-radical production or low antioxidant levels, has recently been implicated as a causative factor in atherogenesis. The aim of this study was to determine if chronic renal failure and haemodialysis were associated with increased oxidative stress. Serum malondialdehyde was measured as a marker of lipid peroxidation in 15 patients with conservatively managed chronic renal failure (CRF), 15 patients with CRF undergoing regular haemodialysis and 15 healthy controls. Selenium, glutathione peroxidase and antioxidant vitamins were also measured. Malondialdehyde was elevated in dialysis patients in comparison to CRF and control groups (dialysis 1.16 +/- 0.08 mumol/l, CRF 0.94 +/- 0.07, controls 0.66 +/- 0.10). Antioxidants, including vitamin C, selenium and glutathione peroxidase, were decreased in dialysis patients and to a lesser extent in the CRF group (vitamin C-dialysis 16.43 +/- 3.76 mumol/l, CRF 34.5 +/- 8.6, controls 56.11 +/- 7.41; selenium-dialysis 0.77 +/- 0.07 mumol/l, CRF 0.69 +/- 0.06, controls 1.09 +/- 0.06: glutathione peroxidase-dialysis 101 +/- 5 U/l, CRF 160 +/- 11, controls 290 +/- 10). These findings indicate oxidative stress in patients with CRF which is further exacerbated by haemodialysis, as evidenced by increased lipid peroxidation and low antioxidant levels. This stress may play a role in the development of atherosclerosis in these groups.

Adult↗
PubMed1993

Distribution of lipid variables in subjects in Belfast, Northern Ireland and Taiyuan, P R China.

To compare the plasma lipid, lipoprotein and apolipoprotein profiles of people of Chinese and European origin, a sample of 151 male Chinese subjects was selected from Taiyuan, Shanxi Province, P R China to 202 broadly age-matched subjects in Belfast who were selected as controls in a case-control study of myocardial infarction. Mean total cholesterol (TC) was 6.15 mmol/l in Belfast and 4.28 mmol/l in Taiyuan. Low density lipoprotein cholesterol (LDL) was much higher in Belfast. High density lipoprotein cholesterol (LDL) was also higher in Belfast than in Taiyuan but the ratio of HDL to TC was lower in Belfast than Taiyuan. Triglyceride (TG) levels were similar and this was reflected in the relatively high level of apolipoprotein E (apo E) in the Chinese sample.

Adult↗
PubMed1992

Isolation and amino acid sequence of urotensin II from the sturgeon Acipenser ruthenus.

Urotensin II (UII) peptides have previously been isolated from the urophysis (the neurohemal organ of the caudal neurosecretory system) of several teleost fish, and the UII amino acid sequences have been determined. Chondrostean fish, such as the Acipenseridae (sturgeon), though without a distinct urophysis, also have a caudal neurosecretory system, which has been indicated by bioassay and immunological evidence to contain UII-like peptides. In the present studies, we investigated by UII radioimmunoassay the UII-like peptides in the spinal cord of three Acipenser species, and isolated and sequenced UII from one of them. As expected, much more UII immunoreactivity (UII-IR) was found in caudal than in anterior spinal cord extracts. In addition, caudal extracts from A. ruthenus were found to contain much more UII-IR (whether determined on a UII-IR/weight or UII-IR/fish basis) than those from the larger A. stellatus and A. guldenstadti. UII was therefore isolated from A. ruthenus and its amino acid sequence was shown to be H-Gly-Ser-Thr-Ser-Glu-Cys-Phe-Trp-Lys-Tyr-Cys-Val-OH. This sequence is identical at positions 6-11 (the disulfide ring) with the known teleost UII peptides, and has acidic and hydrophobic amino acids at positions 5 and 12, respectively, as do the teleost UII peptides. Overall sequence identity with the various forms of teleost UII was 58-83%.

Amino Acid Sequence↗
PubMed1992

Serum copper and zinc in random samples of the population of Northern Ireland.

Serum copper and zinc concentrations (mumol/L) were measured in nonfasting subjects aged 25-64 y participating in two independent population surveys in Northern Ireland. In 1983-84, copper in 1144 males was 17.2 +/- 3.1 (mean +/- SD) and zinc was 12.1 +/- 1.7 (SD). Copper in 1055 females, neither pregnant nor taking estrogens or progestogens, was 19.0 +/- 3.9 and zinc was 11.6 +/- 1.4. In 1986-87 copper in 1142 males was 17.9 +/- 3.3 and zinc was 13.2 +/- 2.1. Copper in 1034 females was 20.1 +/- 3.9 and zinc was 12.7 +/- 2.0. Zinc but not copper concentrations decreased from early morning to late afternoon; both were unaffected by reported postprandial time. There was a positive relationship between copper and age for both sexes but zinc showed only a slight upward trend with age. A positive relationship between copper and the aggregation of classical risk factors for coronary heart disease was demonstrated.

Adult↗
PubMed1992

Plasma manganese levels in the very low birth weight infant are high in early life.

Plasma manganese levels were determined at birth and then serially to 3 months of age in 40 very low birth weight (VLBW) infants (mean birth weight 1,027 g). Mean plasma manganese concentration was 3.6 micrograms/l at birth and 3.0 micrograms/l at 3 months of age. These levels were approximately 3-fold greater than those of a group of 9 adults analysed using the same methods (mean 1.1 micrograms/l). Manganese was also measured in parenteral nutrition fluids, breast milk and 3 preterm formulas. There was no relationship between manganese intake and plasma manganese concentration.

Adult↗
PubMed1992

A case-control study of lipoprotein particles in two populations at contrasting risk for coronary heart disease. The ECTIM Study.

The incidence of coronary heart disease (CHD) in middle-aged men is more than three times higher in Northern Ireland than in France. The ECTIM study, which is based on WHO MONICA centers in Belfast (Northern Ireland), Strasbourg (eastern France), Toulouse (southwestern France), and Lille (northern France), has been established to investigate this striking difference. Male patients aged 25-64 years with myocardial infarction (MI) and control subjects sampled from the general population were recruited in the four centers. Hypolipidemic drug treatment was much more frequent in France than in Belfast. "Hypercholesterolemia" defined by the presence of hypolipidemic drug treatment or a low density liproprotein cholesterol level greater than 200 mg/dl was more frequent in cases than in controls in both countries but was similar in both control groups. An in-depth study of lipid variables, including measurements of cholesterol fractions, triglycerides, apolipoproteins (apo), and lipoprotein particles (Lp), was performed in nonhypercholesterolemic subjects. In Northern Ireland and France, patients in comparison with controls had lower levels of high density lipoprotein cholesterol, apo A-I, apo A-II, Lp A-I, and Lp A-II:A-I and higher levels of Lp E:B and Lp(a):B. The levels of triglycerides, very low density lipoprotein cholesterol, apo B, and Lp C-III:B were higher in cases than in controls only in Belfast. In control subjects, the mean levels of cholesterol fractions and apolipoproteins were similar in Northern Ireland and France; however, the level of Lp A-I was lower and the levels of Lp E:B and Lp(a):B were higher in Northern Ireland than in France.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Plasma manganese, selenium and glutathione peroxidase levels in the mother and newborn infant.

Manganese (Mn), selenium (Se) and glutathione peroxidase (GPX) levels were determined in 56 paired samples of maternal and cord blood plasma at birth in both term and preterm pregnancies. Correlations existed between maternal and newborn plasma levels for Se, but not for Mn or GPX. Values of Mn, Se and GPX were all greater in the term than the preterm infant. Levels of Mn were greater in the pregnant than the non-pregnant woman, but levels of Se and GPX were lower during pregnancy.

Female↗