PubMed Health⌕ Search

Biomedical subjects

A J Burton

Publications and source records attributed to A J Burton.

13 recordsLinked to original sources
PubMed2001

Interleukin 1 receptor antagonist gene polymorphism and restenosis after coronary angioplasty.

BACKGROUND: Percutaneous transluminal coronary angioplasty (PTCA) is limited by the recurrence of luminal stenosis, which occurs in up to 50% of procedures. It has been shown that patient specific factors, perhaps genes, contribute to this process. OBJECTIVE: To determine whether completion of healing after PTCA is part of an acute self limiting inflammatory process and whether polymorphism at important inflammatory gene loci might determine susceptibility to restenosis after PTCA. DESIGN: DNA samples were collected from 171 patients attending for elective PTCA in Sheffield (S) and Leicester (L), who were scheduled to undergo follow up angiography (at four months (L) or six months (S)) as part of other restenosis studies. At follow up angiography, the patients were separated into restenosers (> 50% luminal narrowing) and non-restenosers (< 50% luminal narrowing). Four DNA polymorphisms within interleukin 1 (IL-1) related loci (IL-1A (-889), IL-1B (-511), IL-1B (+3954), and IL-1RN intron 2 VNTR (variable number tandem repeat)) were genotyped using methods based on polymerase chain reaction. Significance was assessed by chi(2) analysis of the relevant contingency table, and the magnitude of effect was estimated by calculating odds ratios. The Mantel-Haenszel (MH) test was applied to summarise data across the two populations. RESULTS: Allele 2 at IL-1RN (IL-1RN*2) was significantly over represented in the non-restenoser group (L+S, 34% v 23% in restenosers). Furthermore, IL-1RN*2 homozygosity was increased in the non-restenoser population compared with the restenosers (MH test: p = 0.0196 (L+S); p = 0.031 (L+S, single vessel disease only), and the effect seemed to be restricted to the single vessel disease subpopulation. For other polymorphism within IL-1 related loci no significant associations were found with either restenosis or non-restenosis. CONCLUSIONS: IL-1RN*2 may be associated with protection from restenosis after PTCA for individuals with single vessel disease. As this polymorphism has functional significance, this finding suggests that alteration in an individual's inflammatory predisposition may modulate the blood vessel response to injury.

Alleles↗
PubMed2000

Prilocaine versus lignocaine for minor lid procedures.

PURPOSE: To determine whether prilocaine is a more comfortable local infiltration anaesthetic agent than the more widely used lignocaine for minor eyelid procedures. METHODS: A prospective randomised study was undertaken to compare the discomfort between local infiltration of plain 2% prilocaine versus its equivalent, plain 2% lignocaine. One hundred and twenty-five patients were recruited. Pain was assessed subjectively using a visual analogue pain score, graded from 0 to 10. RESULTS: The mean pain score for the prilocaine group was 1.82 compared with 3.19 for the lignocaine group. Using the Mann-Whitney U-test for significance, U = 1236.5; p < 0.001. CONCLUSION: Prilocaine is a more comfortable local infiltration anaesthetic agent than lignocaine when used for minor eyelid procedures.

Anesthetics, Local↗
PubMed2000

Reflection: nursing's practice and education panacea?

Nurses are now directed to 'reflect effectively and practice reflectively'. When there is scant evidence to support the use of reflection, why does the United Kingdom Central Council, English National Board for Nursing Midwifery and Health Visiting and institutes of nurse education insist that nurses, at all levels of experience, reflect? Before developing the debate in relation to the robustness or otherwise of the concept of 'reflection' and its application to practice, a discussion as to what constitutes nursing knowledge, followed by an examination of the main theories related to adult learning, is presented. The paper develops to encompass a critical examination of both theoretical and applied perspectives on reflection. Conceptual issues and assumptions related to reflection are explored. Key areas considered are whether the practice of reflection facilitates the improvement of one's knowledge, helps to generate theory and results in one becoming a more critical practitioner with resulting benefits for patients. It will be argued that reflective theory and practice has not yet been adequately tested and that there is a pressing need for evidence to demonstrate irrefutably the effectiveness of reflection on nursing practice, particularly with respect to patient outcomes.

Adult↗
PubMed1999

Obstetric profiles and perinatal mortality among Pacific Island immigrants in New South Wales, 1990-93.

OBJECTIVES: To describe the obstetric profile and perinatal mortality of Pacific Island-born women giving birth in New South Wales (NSW) and assess risk factors associated with the high perinatal death rate previously noted in this immigrant group. METHOD: Retrospective cohort study based on the Midwives Data Collection in NSW from 1990 to 1993. Births to 5,034 Pacific Island-born women were compared with births to 256,843 Australian-born women. RESULTS: Pacific Island-born women had fewer teenage pregnancies and were of an older age and higher parity. They were more likely to be married or in a de facto relationship and to present for antenatal care later in the pregnancy. The proportion of low birthweight and preterm birth was similar in the two groups but Pacific Islanders had a higher perinatal mortality rate (14.6/1,000 vs. 10.3/1,000, RR = 1.42, 95% CI = 1.13-1.54). Even at normal and high birthweights, infants of Pacific Island-born women were at greater risk of perinatal death. After adjusting for maternal factors (marital status, insurance status, parity and maternal age) Pacific Islanders were 30% more likely to have a perinatal death (OR = 1.30, 95% CI 1.07-1.54). CONCLUSIONS: Further analyses of the causes of perinatal death in Pacific Island-born women are needed so appropriate interventions can be implemented. IMPLICATIONS: The need for the design and evaluation of culturally specific services aimed at improving antenatal care attendance in Pacific Islanders is emphasised. Conventional risk assessment may not adequately predict adverse perinatal outcomes in all populations.

Adolescent↗
PubMed1997

Effect of measurement CO(2) concentration on sugar maple root respiration.

Accurate estimates of root respiration are crucial to predicting belowground C cycling in forest ecosystems. Inhibition of respiration has been reported as a short-term response of plant tissue to elevated measurement [CO(2)]. We sought to determine if measurement [CO(2)] affected root respiration in samples from mature sugar maple (Acer saccharum Marsh.) forests and to assess possible errors associated with root respiration measurements made at [CO(2)]s lower than that typical of the soil atmosphere. Root respiration was measured as both CO(2) production and O(2) consumption on excised fine roots (</= 1.0 mm) at [CO(2)]s ranging from 350 to > 20,000 micro l l(-1). Root respiration was significantly affected by the [CO(2)] at which measurements were made for both CO(2) production and O(2) consumption. Root respiration was most sensitive to [CO(2)] near and below normal soil concentrations (< 1500 micro l l(-1)). Respiration rates changed little at [CO(2)]s above 3000 micro l l(-1) and were essentially constant above 6000 micro l l(-1) CO(2). These findings call into question estimates of root respiration made at or near atmospheric [CO(2)], suggesting that they overestimate actual rates in the soil. Our results indicate that sugar maple root respiration at atmospheric [CO(2)] (350 micro l l(-1)) is about 139% of that at soil [CO(2)]. Although the causal mechanism remains unknown, the increase in root respiration at low measurement [CO(2)] is significant and should be accounted for when estimating or modeling root respiration. Until the direct effect of [CO(2)] on root respiration is fully understood, we recommend making measurements at a [CO(2)] representative of, or higher than, soil [CO(2)]. In all cases, the [CO(2)] at which measurements are made and the [CO(2)] typical of the soil atmosphere should be reported.

Journal Article↗
PubMed1996

Fine root respiration in northern hardwood forests in relation to temperature and nitrogen availability.

We examined fine-root (< 2.0 mm diameter) respiration throughout one growing season in four northern hardwood stands dominated by sugar maple (Acer saccharum Marsh.), located along soil temperature and nitrogen (N) availability gradients. In each stand, we fertilized three 50 x 50 m plots with 30 kg NO(3) (-)-N ha(-1) year(-1) and an additional three plots received no N and served as controls. We predicted that root respiration rates would increase with increasing soil temperature and N availability. We reasoned that respiration would be greater for trees using NO(3) (-) as an N source than for trees using NH(4) (+) as an N source because of the greater carbon (C) costs associated with NO(3) (-) versus NH(4) (+) uptake and assimilation. Within stands, seasonal patterns of fine-root respiration rates followed temporal changes in soil temperature, ranging from a low of 2.1 micro mol O(2) kg(-1) s(-1) at 6 degrees C to a high of 7.0 micro mol O(2) kg(-1) s(-1) at 18 degrees C. Differences in respiration rates among stands at a given soil temperature were related to variability in total net N mineralized (48-90 micro g N g(-1)) throughout the growing season and associated changes in mean root tissue N concentration (1.18-1.36 mol N kg(-1)). The hypothesized increases in respiration in response to NO(3) (-) fertilization were not observed. The best-fit model describing patterns within and among stands had root respiration rates increasing exponentially with soil temperature and increasing linearly with increasing tissue N concentration: R = 1.347Ne(0.072T) (r(2) = 0.63, P < 0.01), where R is root respiration rate ( micro mol O(2) kg(-1) s(-1)), N is root tissue N concentration (mol N kg(-1)), and T is soil temperature ( degrees C). We conclude that, in northern hardwood forests dominated by sugar maple, root respiration is responsive to changes in both soil temperature and N availability, and that both factors should be considered in models of forest C dynamics.

Journal Article↗
PubMed1970

Intracellular development of bacteriophage phi-R. II. Fractionation of replicative form deoxyribonucleic acid associated with rapidly sedimenting host cell components.

When Escherichia coli is infected with bacteriophage phiR, parental deoxyribonucleic acid (the single- or double-stranded DNA containing the isotopic label of the infecting phage) becomes firmly attached to a cellular structure and can be isolated as a rapidly sedimenting component as described earlier for phiX174. If this component is centrifuged to equilibrium, two peaks of infective DNA are observed at densities of 1.30 and 1.15 g/ml. At low multiplicities of infection, (32)P-labeled parental DNA is found associated with only the cellular components in the dense band; as the multiplicities of infection are increased, the dense band becomes saturated and parental DNA molecules are then found at the light density as well. Actively replicating host DNA is found only in the dense band, whereas progeny DNA, which does not replicate semiconservatively, can become associated with cellular components in the light band. This fractionation of cellular components on the basis of their buoyant density separates primary sites of DNA replication associated with the dense band from nonfunctional binding sites in the light band.

Carbon Isotopes↗