Showing papers by "University College Dublin published in 1995"

Classification of Walking Handicap in the Stroke Population

Abstract: Background and Purpose The limited walking ability that follows a stroke restricts the patient’s independent mobility about the home and community, a significant social handicap. To improve the in-hospital prediction of functional outcome, the relationships between impairment, disability, and handicap were assessed with clinical measures in 147 stroke patients. Methods The patients’ level of functional walking ability at home and in the community was assigned by expert clinicians to one of the six categories of a modified Hoffer Functional Ambulation scale at least 3 months after discharge. A 19-item questionnaire was further used to assess current customary mobility of the subjects. Functional muscle strength and proprioception were tested, and walking velocity was measured. Results The significant indicators of impairment, upright motor control knee flexion and extension strength, differentiated household from community ambulators. The addition of velocity improved the functional prediction. Propriocept...

Folate levels and neural tube defects. Implications for prevention.

Abstract: Using data from a recent case-control study, a woman's risk of having a child with a neural tube defect (NTD) was found to be associated with early pregnancy red cell folate levels in a continuous dose-response relationship. These findings were used to calculate the reduction in NTD cases that would be expected under two different strategies to raise folate levels. Targeting high-risk individuals has a small effect on the population prevalence but can substantially change an individual's risk. Targeting the population produces a small change in individual risk but has a large effect on the population prevalence. Supplementation of high-risk women would be the most efficient method to implement the high-risk strategy, while food fortification would be preferable for the population approach. The current guidelines for the prevention of NTD are for an increased folic acid intake of 0.4 mg per day. This would result in a 48% reduction in NTDs, which may be near optimal. The two intervention strategies should be considered complementary in prevention of NTDs. (JAMA. 1995;274:1698-1702)

Candida dubliniensis sp. nov.: phenotypic and molecular characterization of a novel species associated with oral candidosis in HIV-infected individuals

Abstract: Atypical oral Candida isolates were recovered from 60 HIV-infected and three HIV-negative individuals. These organisms were germ-tube-positive and produced abundant chlamydospores which were frequently arranged in triplets or in contiguous pairs. They belonged to C. albicans serotype A and had atypical carbohydrate assimilation profiles. Fingerprinting the genomic DNA of a selection of these organisms with the C. albicans-specific probe 27A and five separate oligonucleotides, homologous to eukaryotic microsatellite repeat sequences, demonstrated that they had a very distinct genomic organization compared to C. albicans and C. stellatoidea. This was further established by random amplified polymorphic DNA (RAPD) and karyotype analysis. Comparison of 500 bp of the V3 variable region of the large ribosomal subunit genes from nine atypical isolates and the corresponding sequences determined from C. albicans, C. stellatoidea, C. tropicalis, C. parapsilosis, C. glabrata, C. kefyr and C. krusei showed that they atypical organisms formed a homogeneous cluster (100% similarity) that was significantly different from the other Candida species analysed, but was most closely related to C. albicans and C. stellatoidea. These genetic data combined with the phenotypic characteristics of these atypical organisms strongly suggest that they constitute a novel species within the genus Candida for which the name Candida dubliniensis is proposed.

Effect of pH and temperature on protein unfolding and thiol/disulfide interchange reactions during heat-induced gelation of whey proteins

Abstract: In heat-induced whey protein isolate (WPI) gels, polymerization of the constituent whey proteins, via intermolecular disulfide (S-S) bonding, was dependent on both the pH of the WPI solution and the temperature to which the solution was heated. At pH 9 and 11, polymerization as determined by SDS-PAGE occurred at room temperature (22 o C), while at pH 3, 5, and 7, polymerization was only evident after heating to 85, 75, and 70 o C, respectively. Measurement of total sulfhydryl (SH) group content of gelling WPI solutions at each pH and temperature revealed that in the WPI solutions at pH 9 and 11 significant SH-SH oxidation to S-S occurred even at room temperature. In contrast, the total SH content of WPI solutions at pH 3 and 5 did not change with heating, indicating that polymerization reactions involving SH/S-S interchange rather than SH/SH oxidation predominated. Estimation of the degree of unfolding of the whey proteins by measuring the exposure of hydrophobic amino acid residues showed that at pH 9 and 11 extensive irreversible unfolding of the protein molecules had occurred at room temperature

The role of advertising in brand image development

Abstract: In an increasingly competitive marketplace, greater emphasis is being placed on brand image development as the basis for consumer discrimination. Advertising has a central role to play in developing brand image, whether at the corporate, retail or product level. It informs consumers of the functional capabilities of the brand while simultaneously imbuing the brand with symbolic values and meanings relevant to the consumer. These two functions of advertising closely parallel the informational and transformational schools of advertising effects and theories on the central and peripheral routes to consumer persuasion. Such dichotomous approaches to explanation are unlikely to represent the reality of consumer choice in that brand image is likely to be formed by the simultaneous absorption of advertising messages based on both the functional and expressive capabilities of brands.

Pathophysiology of obstructive sleep apnoea

Abstract: The pathophysiology of obstructive sleep apnoea (OSA) is complex and incompletely understood. A narrowed upper airway is very common among OSA patients, and is usually in adults due to nonspecific factors such as fat deposition in the neck, or abnormal bony morphology of the upper airway. Functional impairment of the upper airway dilating muscles is particularly important in the development of OSA, and patients have a reduction both in tonic and phasic contraction of these muscles during sleep when compared to normals. A variety of defective respiratory control mechanisms are found in OSA, including impaired chemical drive, defective inspiratory load responses, and abnormal upper airway protective reflexes. These defects may play an important role in the abnormal upper airway muscle responses found among patients with OSA. Local upper airway reflexes mediated by surface receptors sensitive to intrapharyngeal pressure changes appear to be important in this respect. Arousal plays an important role in the termination of each apnoea, but may also contribute to the development of further apnoea, because of reduction in respiratory drive related to the hypocapnia which results from postapnoeic hyperventilation. A cyclical pattern of repetitive obstructive apnoeas may result. A better understanding of the integrated pathophysiology of OSA should help in the development of new therapeutic techniques.

An Agent Morality View of Business Policy

Abstract: We develop a philosophical perspective on the moral obligations of managers, which we call agent morality, by examining the moral implications of agency theory. Our view is grounded in noninstrumental ethics, which we argue is logically superior to instrumental ethics. We show that the principal-agent model of the firm, once properly considered, requires that managers fashion business policies with reference first to certain moral duties and second to shareholder wealth.

A mean score method for missing and auxiliary covariate data in regression models

Abstract: SUMMARY We consider regression analysis when incomplete or auxiliary covariate data are available for all study subjects and, in addition, for a subset called the validation sample, true covariate data of interest have been ascertained. The term auxiliary data refers to data not in the regression model, but thought to be informative about the true missing covariate data of interest. We discuss a method which is nonparametric with respect to the association between available and missing data, allows missingness to depend on available response and covariate values, and is applicable to both cohort and case-control study designs. The method previously proposed by Flanders & Greenland (1991) and by Zhao & Lipsitz (1992) is generalised and asymptotic theory is derived. Our expression for the asymptotic variance of the estimator provides intuition regarding performance of the method. Optimal sampling strategies for the validation set are also suggested by the asymptotic results.

Metal cation uptake by yeast: a review.

Abstract: This review addresses metal uptake specifically by yeast. Metal uptake may be passive, active or both, depending on the viability of the biomass, and is influenced by a number of environmental and experimental factors. Uptake is typically accompanied by a degree of ion exchange and, under certain conditions, may be enhanced by the addition of an energy source, Intracellularly accumulated metal is most readily associated with the cell wall and vacuole but may also be bound by other cellular organelles and biomolecules. The intrinsic biochemical, structural and genetic properties of the yeast cell along with environmental conditions are crucial for its survival when exposed to toxic metals. Conditions of pH, temperature and the presence of additional ions, amongst others, have varying effects on the metal uptake process. We conclude that yeasts have contributed significantly to our understanding of the metal uptake process and suggest directions for future work.

Helicobacter pylori requires an acidic environment to survive in the presence of urea

Abstract: The aim of this work was to study the significance of the urease enzyme in promoting Helicobacter pylori survival in various environments. A urease-positive H. pylori isolate, strain N6, and an isogenic urease-negative strain, strain N6(ureB::TnKm), were incubated in phosphate-buffered saline at a pH ranging from 2.2 to 7.2 for 60 min at 37 degrees C in both the presence and the absence of 10 mM urea. The number of CFU per milliliter in each solution, the pH of the bacterial supernatant, and the amounts of ammonia present in the solutions were measured. H. pylori N6 survived well in solutions with pH values ranging from 4.5 to 7.0 in the absence of urea but survived in solutions only with an initial pH below 3.5 in the presence of urea. Neither strain grew after incubation in an alkaline environment. The pH of an acidic solution (i.e., 3.5) rose rapidly to 8.45 in the presence of the wild-type strain and urea. The urease-negative mutant survived in solutions with pH values ranging from 4.5 to 7.2 irrespective of the presence of urea. Ammonia was present in significant amounts when H. pylori N6 was incubated in the presence of urea. Strain N6 survived exposure to concentrations of ammonia as high as 80 mM. The acid environment of the stomach may be crucial for H. pylori survival in the presence of urea. H. pylori does not survive in the normal environment in the presence of urea because of the subsequent rise in pH rather than ammonia toxicity.

Regulation of Pollen Tube Growth

Abstract: Most textbooks describe pollen and pollen tubes as the vectors carrying the male sperm cells in seed plants. The pollen tubes grow through the style to the ovule, where the sperm cells are delivered to the egg cells in the embryo sacs. Pollen tubes always grow in an alien environment: in evolutionary terms they derive from the haustorium through which the primitive microgametophyte fed on the sporophyte. Haustorial forms are still found in the case of ramified pollen tubes of gymnosperms that survive and feed for a long period in the female cone. Pollen tubes have a specific form of intrusive growth, or tip growth. Other cells with tip growth include root hairs, bipolar extending tracheids and fibre cells, and also many organisms such as a number of algae, moss and fern protonemal cells and most fungal hyphae. Diverse as they are, these cell types basically share the same cytoplasmic constituents and thus may show many similarities in behaviour to each other. However, the large evolutionary distance between the fungi (including Oomyceta) and the Phaeophyta may have allowed different modes of tip growth to develop.

Functional analysis and treatment of escape‐maintained aggression correlated with sleep deprivation

Abstract: Functional analysis identified the consequences that maintained aggressive behavior and the relationship between these consequences and sleep deprivation for an individual with severe mental retardation. Results showed that aggression was maintained by negative reinforcement contingencies (escape from demand) and that aggression was more severe when sleep deprivation was present. A multicomponent intervention resulted in reductions of aggression for up to 7 months.

Multiwavelength Observations of Markarian 421 During a TeV/X-Ray Flare

Abstract: A TeV flare from the BL Lac object Mrk 421 was detected in May of 1994 by the Whipple Observatory air Cherenkov experiment during which the flux above 250 GeV increased by nearly an order of magnitude over a 2-day period. Contemporaneous observations by ASCA showed the X-ray flux to be in a very high state. We present these results, combined with the first ever simultaneous or nearly simultaneous observations at GeV gamma-ray, UV, IR, mm, and radio energies for this nearest BL Lac object. While the GeV gamma-ray flux increased slightly, there is little evidence for variability comparable to that seen at TeV and X-ray energies. Other wavelengths show even less variability. This provides important constraints on the emission mechanisms at work. We present the multiwavelength spectrum of this gamma-ray blazar for both quiescent and flaring states and discuss the data in terms of current models of blazar emission.

Amplification of the MDM2 gene in human breast cancer and its association with MDM2 and p53 protein status.

Abstract: The present study reports on the frequency of MDM2 gene amplification and MDM2 protein expression in a series of 100 breast carcinomas and its association with accumulation of the p53 protein. Of the 100 cases, frozen samples for 82 cases were available for Southern blotting. Three of the 82 (4%) demonstrated MDM2 gene amplification of up to 6-fold. Immunohistochemical analysis of the formalin-fixed, paraffin-embedded tumours demonstrated that 7/97 (7%) had nuclear expression for MDM2 in 10-50% of the tumour cells (type 2 staining) and were denoted MDM2+. Two of the MDM2-amplified samples were MDM2+ with one of the two tumours also displaying type 2 p53 nuclear staining. Finally at the protein level, MDM2+ tumours were significantly associated with tumours having low levels of p53 staining (0-10% cells positive) (P = 0.03). We conclude that MDM2 gene amplification occurs at a lower frequency in breast cancer than in non-epithelial tumours. Alterations in MDM2 and p53 may represent alternative pathways in tumorigenesis, but they are not mutually exclusive in all cases.

Immunization of heifers against gonadotropin-releasing hormone: antibody titers, ovarian function, body growth, and carcass characteristics

Abstract: To investigate the effects of active immunization of cyclic beef heifers with different doses of a human serum albumin-Cys-Gly-GnRH (HSA-GnRH) conjugate on antibody titers, ovarian function, body growth, and carcass characteristics, 32 heifers (BW = 477 ± 7.1 kg ; mean ± SE) were assigned to one of four immunization treatments :.1 mg of HSA or.01,.1, or 1.0 mg of HSA-GnRH, respectively. All heifers received a primary (d 0) and booster (d 28) immunization using DEAE-dextran as adjuvant. The duration of the experiment was 158 d. Overall antibody titers against GnRH were greater (P 21 d) were 1/8, 8/8, 7/8, and 8/8, respectively. The interval from primary immunization to anestrus (40.7 ± 6 d) and the duration of anestrus (78 ± 7 d) were not affected by dose of HSA-GnRH conjugate. The number of ovulations detected was reduced (P .10) of treatment on overall growth rate (ADG.54 ±.041 and.51 ±.054 kg for control and GnRH-immunized heifers, respectively) or carcass measurements. However, ADG was reduced for GnRH-immunized heifers between d 56 and 84. In , immunization of heifers with a HSA-GnRH conjugate invoked an immune response in all heifers and induced anestrus in 23/24 heifers for 82.8 ± 6.9 d ; dose of HSA-GnRH conjugate did not affect the incidence or duration of anestrus.

A typology of technology‐based entrepreneurs

Abstract: Despite increasing evidence of the use of typologies in entrepreneurship research, comparatively little work has attempted to distinguish between different types of technical entrepreneur. Aims to develop such a typology. Examines previous research into the organizational backgrounds from which technical entrepreneurs have emerged to form new ventures. Follows this with an analysis of detailed qualitative interviews administered to a sample of technical entrepreneurs in the United Kingdom, which leads to the formulation of a typology of technical entrepreneurs based on their previous occupations and, in particular, on the role played by the technical entrepreneurs in the development of technology with past employers.

Insights into thermal stability from a comparison of the glutamate dehydrogenases from Pyrococcus furiosus and Thermococcus litoralis.

Abstract: In the light of the solution of the three-dimensional structure of the NAD+-linked glutamate dehydrogenase from the mesophile Clostridium symbiosum, we have undertaken a detailed examination of the alignment of the sequences for the thermophilic glutamate dehydrogenases from Thermococcus litoralis and Pyrococcus furiosus against the sequence and the molecular structure of the glutamate dehydrogenase from C. symbiosum, to provide insights into the molecular basis of their thermostability. This homology-based modelling is simplified by the relatively small number of amino acid substitutions between the two thermophilic glutamate dehydrogenase sequences. The most frequent amino acid exchanges involve substitutions which increase the hydrophobicity and sidechain branching in the more thermostable enzyme; particularly common is the substitution of valine to isoleucine. Examination of the sequence differences suggests that enhanced packing within the buried core of the protein plays an important role in maintaining stability at extreme temperatures. One hot spot for the accumulation of exchanges lies close to a region of the molecule involved in its conformational flexibility and these changes may modulate the dynamics of this enzyme and thereby contribute to increased stability.

Accumulation of arsenic and zinc in the rhizosphere of wetland plants

Abstract: Oxidation of the rhizosphere by wetland plants leads to precipitation of iron oxyhydroxides (ironplaque) in the rhizosphere and on the root surface of the plants. Arsenic and zinc have a high binding affinity for iron oxyhydroxides and were found to accumulate in ironplaque on roots of Aster tripolium L. It was argued that rhizosphere oxidation and formation of an ironplaque would favor the accumulation of iron, arsenic and zinc in the rhizosphere. Oxidation of ferrous iron to its ferric form would lead to precipitation of iron oxyhydroxides in the rhizosphere, which in turn would lead to a decreasing concentration gradient of dissolved iron towards the plant roots. The iron oxyhydroxides in turn would bind arsenic and zinc, again creating a decreasing concentration gradient of both elements towards the roots. These gradients would lead to the diffusion of iron, arsenic and zinc in the direction of the roots. Assuming that uptake of the elements by the roots is slower than supply through diffusion, an increase in concentrations of all three elements would be expected to occur in the solid phase of the rhizosphere. The plant-induced processes in wetland soils may not only affect the availability of zine and arsenic to plantsmore » but also may play an important role in the sink function of wetlands for metals and metalloids. This paper reports the results of a pilot field study which compared concentrations of the metals in ironplaque, rhizosphere soil and bulk soil under Spartina anglica and Halimione portulacoides. 20 refs., 3 figs., 2 tabs.« less

The effects of elevated CO2 concentrations on the root growth of Lolium perenne and Trifolium repens grown in a FACE* system

Abstract: Lolium perenne and Trifolium repens were grown in a Free Air CO2 Enrichment (FACE) system at elevated (600 μimol mol-1) and ambient (340 μmol mol-1) carbon dioxide concentrations during a whole growing season Using a root ingrowth bag technique the extent to which CO2 enrichment influenced the growth of L, perenne and T repens roots under two contrasting nutrient regimes was examined Root ingrowth bags were inserted for a fixed time into the soil in order to trap roots It was also possible to follow the mortality of roots in bags inserted for different time intervals Root ingrowth of both L perenne and T repens increased under elevated CO2 conditions In L perenne, root ingrowth decreased with increasing nutrient fertilizer level, but for T repens the root ingrowth was not affected by the nutrient application rate Besides biomass measurements, root length estimates were made for T, repens These showed an increase under elevated CO2 concentrations Root decomposition appeared to decrease under elevated CO2 concentrations A possible explanation for this effect is the observed changes in tissue composition, such as the increase in the carbon: nitrogen ratio in roots of L perenne at elevated CO2 concentrations

Behavioural pharmacology op ‘D-1-like’ dopamine receptors: Further subtyping, new pharmacological probes and interactions with ‘D-2-like’ receptors

Abstract: 1. 1. D-1 receptors are now recognised to play a critical psychopharmacological role in the regulation of unconditioned motor and numerous other aspects of behaviour. 2. 2. There appears to exist a broad family of ‘D-1-like’ receptors in terms both of differential coupling to distinct messenger/transduction mechanisms and of gene cloning, whose behavioural roles remain to be clarified. 3. 3. The adenylyl cyclase-inhibiting benzazepine SKF these data indicate roles for individual ‘D-1-like’ receptors in mediating distinct elements of dopaminergic behaviour. 4. 4. The putative D-1 autoreceptor agonist B-HT 920 and the putative D-3 agonist 7-OH-DPAT demonstrate different behavioural profiles when given both alone and in combination with the selective ‘D-1-like’ antagonist BW 737C; D-3 receptors may participate in cooperative/synergistic but not in oppositional ‘D-1-like’: ‘D-2-like’ interactions. 5. 5. Such interactions apparent at the level of behaviour are complemented by evidence for similar interactions at numerous alternative levels of function, though these may differ between rodent and primate species. 6. 6. A broader range of more selective agonists and antagonists, able to distinguish between individual members of the ‘D-1-like’ and of the ‘D-2-like’ receptor families are needed to clarify these issues.

Non-enzymic glycation of fibrous collagen: reaction products of glucose and ribose.

Abstract: Non-enzymic glycation of collagen involves a series of complex reactions ultimately leading to the formation of intermolecular cross-links resulting in changes in its physical properties. During analysis for the fluorescent cross-link pentosidine we identified the presence of an additional component (Cmpd K) in both glucose and ribose incubations. Cmpd K was formed more quickly than pentosidine in glucose incubations and more slowly than pentosidine in ribose incubations. Cmpd K represented 45% of the total fluorescence compared with 15% for pentosidine in glucose incubations and 25% of the total fluorescence compared with 30% for pentosidine in the ribose incubations. Cmpd K is not an artefact of in vitro incubations, as it was shown to be present in dermal tissue from diabetic patients. Subsequent high-resolution h.p.l.c. analysis of glucose-incubated collagen revealed Cmpd K comprise two components (K1 and K2). Further, a similar analysis of Cmpd K from the ribose incubations revealed two different components (K3 and K4). These differences indicate alternative mechanisms for the reactions of glucose and ribose with collagen. The amounts of these fluorescent components and the pentosidine cross-link determined for both glucose and ribose glycation were found to be far too low (about one pentosidine molecules per 200 collagen molecules after 6 months incubation with glucose) to account for the extensive cross-linking responsible for the changes in physical properties, suggesting that a further additional series of cross-links are formed. We have analysed the non-fluorescent high-molecular-mass components and identified a new component that increases with time of in vitro incubation and is present in the skin of diabetic patients. This component is present in sufficient quantities (estimated at one cross-link per two collagen molecules) to account for the changes in physical properties occurring in vitro.

The earthworm population of a winter cereal field and its effects on soil and nitrogen turnover.

Abstract: The earthworm population in a winter cereal field in Ireland was studied over a 3-year-period and its effects on soil and N turnover were assessed. The mean annual population density was 346–471 individuals m-2 and the mean biomass was 56.9–61.2 g m-2. Twelve species were recorded, the most abundant being Allolobophora chlorotica followed by Aporrectodea caliginosa, and 242 mg at 5°C to 713 mg at 10°C in the case of juvenile Lumbricus terrestris. Gut contents (dry mass of soil) comprised 6.7–15.5% of the A. caliginosa live mass, and 9.7–14.7% of the Lumbricus terrestris mass. Annual soil egestion by the field population was estimated as 18–22 kg m-2. Tissue production ranged from 81.7 to 218.5 g m-2, while N turnover resulting from mortality was calculated as 1.5–3.9 g m-2 depending on the year and the method of calculation. Earthworms were estimated to contribute an additional 3.4–4.1 g mineral N to the soil through excretion, mucus production, and soil ingestion. Independent estimates of N output via mucus and excretion derived from 15N laboratory studies with Lumbricus terrestris were 2.9–3.6 g m-2 year-1.

Single longitudinal mode ridge waveguide 1.3µm Fabry-Perot laser by modal perturbation

Abstract: The authors introduce a cost effective technique which converts the multi-longitudinal mode output of a 1.3 /spl mu/m ridge waveguide Fabry-Perot laser into a single mode by creating modal perturbations along the length of the ridge. Up to 25 dB side mode supression is measured on their first lasers.