Showing papers by "Queen's University Belfast published in 1992"

Deletion polymorphism in the gene for angiotensin-converting enzyme is a potent risk factor for myocardial infarction.

Abstract: Factors involved in the pathogenesis of atherosclerosis, thrombosis and vasoconstriction contribute to the development of coronary heart disease. In a study comparing patients after myocardial infarction with controls, we have explored a possible association between coronary heart disease and a variation found in the gene encoding angiotensin-converting enzyme (ACE). The polymorphism ACE/ID is strongly associated with the level of circulating enzyme. This enzyme plays a key role in the production of angiotensin II and in the catabolism of bradykinin, two peptides involved in the modulation of vascular tone and in the proliferation of smooth muscle cells. Here we report that the DD genotype, which is associated with higher levels of circulating ACE than the ID and II genotypes, is significantly more frequent in patients with myocardial infarction (n = 610) than in controls (n = 733) (P = 0.007), especially among subjects with low body-mass index and low plasma levels of ApoB (P < 0.0001). The ACE/ID polymorphism seems to be a potent risk factor of coronary heart disease in subjects formerly considered to be at low risk according to common criteria.

Impaired endothelium-dependent and independent vasodilation in patients with type 2 (non-insulin-dependent) diabetes mellitus.

Abstract: The endothelium plays a pivotal role in modulating the reactivity of vascular smooth muscle through the formation of several vasoactive substances. We examined the effects of endothelium-dependent and independent vasodilators on forearm blood flow in 29 patients with Type 2 (non-insulin-dependent) diabetes mellitus and in 21 control subjects, using venous occlusion plethysmography. Via a brachial artery cannula, increasing amounts of acetylcholine and glyceryl trinitrate were infused in doses of 60, 120, 180 and 240 mmol per min and 3, 6 and 9 nmol per min respectively. NG monomethyl-l-arginine, a stereospecific inhibitor of endothelium derived relaxing factor, was infused to inhibit basal and stimulated release of this dilator substance. Reactive hyperaemic forearm blood flow did not differ between groups. Forearm blood flow responses to each dose of acetylcholine were significantly greater in control than diabetic subjects (p<0.01 for all doses). NG monomethyl-l-arginine attenuated forearm blood flow from maximal stimulated values when responses were compared with the natural decline to acetylcholine in forearm flow in both control and diabetic subjects (p<0.05 for both groups), but had no effect on basal blood flow responses. Forearm blood flow responses to each dose of glyceryl trinitrate were significantly greater in control than diabetic subjects (p<0.05 for all). These data provide evidence for endothelial and smooth muscle dysfunction in diabetes which may have important therapeutic implications.

A simplified protocol for routine total DNA isolation from salmonid fishes

Abstract: An efficient total DNA isolation protocol, suitable for routine population genetic screening purposes is described. This phenol based extraction can utilize fresh, frozen or ethanol preserved tissues.

Smectogenic dimeric liquid crystals. The preparation and properties of the α,ω-bis(4-n-alkylanilinebenzylidine-4′-oxy)alkanes

Abstract: Eleven series of dimeric liquid crystals, namely the α,ω-bis(4-n-alkylanilinebenzylidine-4′-oxy)alkanes, have been synthesized and their transitional properties characterized. The number of methylene groups in the flexible core was varied from one to twelve while the length of the terminal alkyl chains was increased from a methyl group to a decyl substituent. The rich smectic polymorphism of this family of compounds was studied using X-ray diffraction and polarizing microscopy; it includes several examples of rare phase transitions, for example, smectic F-smectic A and crystal G-isotropic, as well as novel modulated hexatic phases based on a two dimensional lattice. The transitional properties of a given series, where the length of the terminal chain is held constant while the length and parity of the flexible spacer is varied, exhibit a pronounced alternation. For example, the entropy change at the nematic-isotropic transition exhibits a strong alternation and this has been interpreted in terms ...

Comparison of intubating conditions after administration of Org 9426 (rocuronium) and suxamethonium

Abstract: We have assessed intubating conditions after administration of Org 9426 (rocuronium) 600 fig kg−1 at 60 or 90s in groups of 20 patients anaesthetized with thiopentone, nitrous oxide in oxygen and small doses of fentanyl, and compared the data with those obtained after suxamethonium 1 mg kg−1 in similar groups of patients. The influence of prior suxamethonium administration on the potency of Org 9426 was studied also by constructing a dose-response curve. Intubating conditions after Org 9426 were found to be clinically acceptable (good or excellent) in 95% of patients at 60 s and in all patients at 90 s and in all patients at both times after suxamethonium. The average time for the onset of block following Org 9426 at this dose was 89 s (which is shorter than with any of the currently available non-depolarizing neuromuscular blocking drugs); the duration of clinical relaxation (25% recovery of twitch height) 30 min. Prior administration of suxamethonium did not appear to influence the potency of Org 9426.

Detection and differentiation of Colletotrichum gloeosporioides isolates using PCR.

Abstract: An oligonucleotide primer (CgInt), synthesised from the variable internally transcribed spacer (ITS) 1 region of ribosomal DNA (rDNA) of Colletotrichum gloeosporioides was used for PCR with primer ITS4 (from a conserved sequence of the rDNA) to amplify a 450-bp fragment from the 25 C. gloeosporioides isolates tested. This specific fragment was amplified from as little as 10 fg of fungal DNA. A similar sized fragment was amplified from DNA extracted from C. gloeosporioides-infected tomato tissue. RAPD analysis divided 39 C. gloeosporioides isolates into more than 12 groups linked to host source and geographic origin. Based on the results obtained, the potential of PCR for detection and differentiation of C. gloeosporioides is discussed.

Rock glaciers : II models and mechanisms

Abstract: This second part of a review deals with the mechanisms of rock glacier formation and flow. The presence of a copious debris supply is important in all models, although the source of ice necessary f...

Intraventricular infusions of anti-neural cell adhesion molecules in a discrete posttraining period impair consolidation of a passive avoidance response in the rat.

Abstract: Intraventricular infusions of anti-neural cell adhesion molecule (anti-NCAM) are demonstrated to inhibit consolidation of a passive avoidance response when administered in the 6-8-h posttraining period. Anti-NCAM was ineffective when administered during training or at any other time up to 10 h thereafter, and no amnesic effects were observed with absorbed anti-NCAM or anti-neurofilament protein. Amnesia was observed only at the 48-h recall time, and this could not be attributed to poor antibody penetration or a prolonged residence time, as studies with 125I-labelled anti-NCAM in trained animals demonstrated a rapid accumulation into all brain regions, and this was marked in the olfactory bulb and hippocampus, areas showing an inherent and paradigm-specific increase in NCAM sialylation state, respectively. The lack of an amnesic action at the 24-h recall time is attributed to anti-NCAM-impaired synapse structuring becoming apparent following the paradigm-specific increases in NCAM sialylation state.

Towards a tephrochronology for the Holocene of the north of Ireland

Abstract: Discrete layers of tephra have been found in both raised and blanket bogs in the north of Ireland. Some of the layers have been identified to an Icelandic source and, in two cases, specific eruptions of known radiocarbon age are suggested. Nine layers spanning the Holocene are replicated in three lowland raised bogs. One of the major layers has also been identified at a number of sites in two separate upland blanket peat systems and in a lake sediment.

A neural network regulator for turbogenerators

Abstract: A neural network (NN) based regulator for nonlinear, multivariable turbogenerator control is presented. A hierarchical architecture of an NN is proposed for regulator design, consisting of two subnetworks which are used for input-output (I-O) mapping and control, respectively, based on the back-propagation (BP) algorithm. The regulator has the flexibility for accepting more sensory information to cater to multi-input, multioutput systems. Its operation does not require a reference model or inverse system model and it can produce more acceptable control signals than are obtained by using sign of plant errors during training I-O mapping of turbogenerator systems using NNs has been investigated and the regulator has been implemented on a complex turbogenerator system model. Simulation results show satisfactory control performance and illustrate the potential of the NN regulator in comparison with an existing adaptive controller. >

Hippocampal NCAM180 transiently increases sialylation during the acquisition and consolidation of a passive avoidance response in the adult rat.

Abstract: Synaptic connectivity change is a consistent anatomical feature of memory formation and the possibility that this is mediated by a replay of neurodevelopmental events has been investigated by measuring change in neural cell adhesion molecule sialylalion state during the acquisition and consolidation of a passive avoidance response in the adult rat. The avoidance response was always generated after two to three trials and the animals remained on the platform for the criterion time of 5 min. In all cases training was complete within 5–8 min. Change in sialylation state was monitored following intrayentricuiar infusion of the 3H-ManNAc Precursor at 4 hr prior to the reference point. No task-specific change in general glycoconjugate sialylation was apparent in hippocampal P2 pellets at increasing times following training. Increased sialylation state was observed only in neural cell adhesion molecule (NCAM) immunoprecipitates of hippocampal membrane fractions at 12 and 24 hr after training. Change in hippocampal sialylation state could not be attributed to an increased accumulation of NCAM as detected by an immunoabsorbent assay. Immunoblotting of antibody precipitated NCAM demonstrated the 3H-ManNAc to be incorporated into the synapse-specific, 180 kDa isoform of NCAM and a novel 210 kDa isoform. Immunoprccipitation and immunoblotting procedures with an antibody specific for a2-8-polysialic acid showed the 180 and 210 kDa isoforms to be polysialylated. The role of NCAM180 sialylation as a mechanism for synapse selection in information storage is discussed.

Post-primary school pupil's interest in physical education: age and gender differences.

Abstract: Interest in Physical Education (PE) was studied in 3,344 11 to 18 year-old school children. Five aspects of educational importance (PE connotation, PE status, PE teacher, PE curriculum, and adolescent disturbances in relation to the PE lesson) were identified, and examined in relation to pupils' interest. For the younger age groups girls' interest in PE was significantly higher than that of the boys, while after the age of 14 the reverse was the case. The status of PE as a school subject was found to be the most important variable for interest in PE. The contribution of the PE teacher to pupils' level of interest was the least important of the factors examined. The results are discussed in terms of the differing importance for boys and girls of sport in social status systems for peer popularity. Suggestions for changes to PE lessons are offered.

A modified manual method for the determination of urea in seawater using diacetylmonoxime reagent

Abstract: A manual method for the quantitative determination of urea in seawater was developed based on the reaction of urea with diacetylmonoxime. Critical factors include the treatment of collection bottles, sample storage, pre-filtration techniques, water purification, reaction temperature and reproducible cooling of samples during analysis. The limit of detection was 0·14 μg-at urea-N 1 −1 with Beer's Law being obeyed in the range tested of 0–15 μg-at urea-N 1 −1 . The precision (±1 SD) of replicate samples of 1,2 and 15 μg-at urea-N 1 -1 was 0·024, 0·019 and 0·03 μg-at urea-N 1 −1 ( n = 10) respectively.

Surface-induced phase transition in normal alkane fluids

Abstract: The surface tension of normal liquid alkanes (chain lengths between 15 and 18 carbon atoms) has been measured as a function of temperature. In all cases the tension exhibits a well-defined change in behavior at a temperature close to, but distinct from, the melting point. The phenomena are consistent with a surface-induced phase transition in which the conformational degrees of freedom of molecules close to the surface are inhibited. Various properties of the transition vary smoothly with alkane chain length.

Synergistic interaction between midazolam and propofol

Abstract: We gave either midazolam or propofol for induction of anaesthesia to 140 ASA I or II female patients (18–60 yr). ED50, values were obtained by probit analysis for three clinical end-points: loss of response to command; loss of eyelash reflex; failure to respond to application of an anaesthetic face mask delivering 1 % isoflurane. Propofol ED50 values (95% confidence intervals) were 1.25 (0.99–1.48) mgkg−1, 1.61 (1.29–1.94) mg kg−1 and1.51 (1.20–1.82) mg kg−1, respectively. ED50 values for midazolam were 0.26 (0.20–0.37) mg kg−1, 0.29 (0.23–0.47) mgkg−1 and 0.25 (0.20–0.32) mg kg−1, respectively. An additional 92 similar patients received one of nine dose combinations of midazolam and propofol for induction of anaesthesia, propofol being administered 2 min after midazolam. Success of induction was based on the clinical end-point of loss of response to command. Administration of 25% of the ED50 of midazolam followed by 50% of the ED50 of propofol resulted in loss of response to command in 50 % of patients, while 50 % of the ED50 of midazolam, followed by 25% of the ED50 of propofol had the same effect. A probit regression model specifying a synergistic interaction between midazolam and propofol fitted the data significantly better than a model specifying no interaction.

Viable but non‐culturable forms of potentially pathogenic bacteria in water

Abstract: In an aquatic environment pathogenic bacteria which are capable of growth in warm-blooded hosts may be stressed by starvtion or by exposure to sub-optimal temperature, salinity or toxic chemicals. Microbial cells may enter a viable but non-growing state, as a result of such sub-lethal stresses and as a strategy for survival, in a dormant form until environmental conditions change. The isolation of micro-organisms by growth on selective media has been universally applied for the detection of viable micro-organisms in water. The reliability of culture methods is of particular importance in testing for the presence of pathogenic micro-organisms and microbial indicators of faecal polution and in monitoring the release and survival of genetically modified micro-organisms in water

Studies on modified chitosan membranes. I. Preparation and characterization

Abstract: Chitin was isolated from prawn shells, and chitosan was prepared from it. The degree of N-deacetylation and the molecular weight were determined using IR spectroscopy and viscometry, respectively. A series of different modified chitosan membranes were prepared by blending with polyvinylpyrrolidone (PVP). These membranes were characterized by various techniques, including differential scanning calorimetry (DSC), wide-angle X-ray diffractometry (WAXD), and tensile testing. The physical, thermal, and mechanical properties were evaluated, and the change in these properties upon the addition of PVP into the blends has been discussed in terms of the amorphous and hydrophilic nature of PVP. Hydrophilicity of the blends increases due to the presence of PVP in the chitosan substrate. This helps in breaking the hydrogen bonds in between chitosan molecules and causes the blends to swell in three dimensions.

Women in a women's job:: the gendered experience of nurses

Abstract: The aim of this paper is to examine how the structural influence of gender affects nurses in their working lives. Gender segregation exists both within and between the occupations of medicine and nursing. It is largely founded on the social construction of a skills/caring dichotomy. An analysis of how the gender of nurses and doctors affects their interactions with co-workers reveals that the increasing proportion of female doctors has attenuated power differences between the two occupations. Examination of nurses' attitudes to gender demonstrates that they are very aware of the problem, despite a tendency to accept credentialist justifications of inequality. As a result of this they are becoming more assertive. The issue of sexual stereotyping is addressed and it is noted that popular mythology about sexual relations between doctor and nurses is highly misleading. Privatised aspirations are having a decreasing influence over nurses' working lives. In conclusion, while gender inequality is losing some of its power in nurse-doctor relationships, it is becoming an increasingly significant factor in the relationship between male nurse managers and female workers.

Luminescence and charge transfer. Part 2. Aminomethyl anthracene derivatives as fluorescent PET (photoinduced electron transfer) sensors for protons

Abstract: The importance of the modular structure ‘fluor-spacer-amine ’is pointed out for the design of fluorescent molecular sensors for pH according to the principle of photoinduced electron transfer (PET). Anthracen-9-yl methylamines (24) and some azacrown ether analogues (15 and 23) are examined in this context. They show pH-dependent fluorescence quantum yields describable by eqn. (5) while all other electronic spectral parameters remain essentially pH-invariant. The range of pKa values of these sensors are understandable in terms of macrocyclic effects and the transmission of electric fields across the anthracene short axis. Phase-shift fluorometric determination of the fluorescence lifetimes of these sensors allows the calculation of the rate constant of PET in their proton-free form to be 1010–1011 s–1, with the diamines 23 and 24b exhibiting the faster rates.

Occurrence of Listeria species in raw milk and dairy products produced in Northern Ireland.

Abstract: J. HARVEY AND A. GILMOUR. 1992. The overall incidence of Listeria spp. in raw milk samples surveyed was found to be 25.0% (Listeria monocytogenes 15.3%), with the incidence in samples from processing centres 54.0% (L. monocytogenes 33.3%); this was higher than that in samples from dairy farms (Listeria spp. 8.8%L. monocytogenes 5.3%). The FDA enrichment procedure was much more productive than cold enrichment and Oxford agar was superior to modified McBride agar for isolation of Listeria. Listeria monocytogenes was never isolated by direct plating of raw milk samples on Oxford agar at a detection level of 1.0 cfu/ml. Listeria spp. were isolated from 1 of 95 pasteurized milk samples (L. monocytogenes) and 1 of 33 soft cheese samples (L. seeligeri). Restriction fragment length polymorphism was more useful than sero- or phage-typing for typing of L. monocytogenes strains, and results suggest that specific L. monocytogenes strains may persist in both farm and processing environments.

Co‐ordination of pumping in isolated bovine lymphatic vessels.

Abstract: 1. Segments of bovine mesenteric lymphatic of varying diameter taken from different parts of the lymphatic tree were cut to 20 mm in length and set up so that measurements could be made of spontaneous isometric contractions. 2. There was considerable variability in frequency of spontaneous contractions but this was independent of resting tension. There was no significant correlation between lymphatic diameter and inherent frequency of contraction. 3. Isolated segments of bovine mesenteric lymphatic 70-80 mm in length were cannulated and set up in a three-compartment organ bath which allowed independent temperature control in each compartment. Pressure was recorded at inflow and outflow ends and experiments were video recorded. 4. Contractile activity was normally initiated at the end of the lymphatic maintained at the higher temperature and the contractile wave was propagated along the length of the vessel. 5. Propagation could occur either in the direction of valve orientation (orthograde) or retrogradely. The volume of fluid pumped was not significantly affected by the direction of propagation. 6. Perfusion of the central compartment with Krebs solution at 0-2 degrees C disrupted normal propagation and allowed the two parts of the lymphatic to contract at different frequencies although the two parts maintained an approximately 2:1 ratio. 7. Perfusion of the central compartment with 10 mM-heptanol also disrupted normal propagation but the rates on either side of the partition bore no harmonic relationship to one another. 8. These results suggest that relatively short segments of lymph duct have the ability to contract spontaneously and that their inherent frequencies are not determined by their position in the lymphatic tree. The results are consistent with the existence of electrical coupling along the lymphatic's length and they suggest that over distances of at least 80 mm independent pacemakers are capable of mutual entrainment at a frequency representing a compromise between the fastest and slowest components.