Showing papers by "Cardiff University published in 1996"

Correlative Memory Deficits, Aβ Elevation, and Amyloid Plaques in Transgenic Mice

Abstract: Transgenic mice overexpressing the 695-amino acid isoform of human Alzheimer beta-amyloid (Abeta) precursor protein containing a Lys670 --> Asn, Met671 --> Leu mutation had normal learning and memory in spatial reference and alternation tasks at 3 months of age but showed impairment by 9 to 10 months of age. A fivefold increase in Abeta(1-40) and a 14-fold increase in Abeta(1-42/43) accompanied the appearance of these behavioral deficits. Numerous Abeta plaques that stained with Congo red dye were present in cortical and limbic structures of mice with elevated amounts of Abeta. The correlative appearance of behavioral, biochemical, and pathological abnormalities reminiscent of Alzheimer's disease in these transgenic mice suggests new opportunities for exploring the pathophysiology and neurobiology of this disease.

Making sense of qualitative data

Abstract: Originally published in Contemporary Psychology: APA Review of Books, 1997, Vol 42(7), 650-650. In Making Sense of Qualitative Data: Complementary Research Strategies (see record 1996-98161-000), Coffey and Atkinson present general strategies and philosophies for collecting and utilizing qualitative

Electrosurgical generator and system

Abstract: In an electrosurgical generator for generating radio frequency power, the generator includes a radio frequency output stage having two or more output connections, and a power supply coupled to the output stage for supplying power to the output stage. A controller is operable to cause the generator to supply a blended output signal alternating constantly between a first output signal across the output connections in which the radio frequency output voltage developed across the output connections is limited to at least a first predetermined threshold value for cutting or vaporisation of tissue, and a second output signal across the output connections in which the radio frequency output voltage developed across the output connections is limited to a second threshold value for coagulation. There is also provided adjustment means, operable by a user of the electrosurgical generator, for changing between various preset settings for the blended signal, the preset settings each having a predetermined duty cycle of the blended signal that is limited to the first threshold value for cutting or vaporisation, and a predetermined duty cycle of the blended signal that is limited to the second threshold value for coagulation.

An electrosurgical instrument and an electrosurgical electrode assembly

Abstract: An electrosurgical instrument primarily intended for so-called "underwater" electrosurgery has a radio frequency generator, a handpiece, and an electrode assembly detachably mounted to the handpiece. Different electrode assemblies may be selected according to the surgical procedure to be performed. To adapt the generator characteristics for improved electrosurgical performance, each electrode assembly contains an identification element such as a capacitor of unique value which is sensed by the generator. Inside the generator, the sensed capacitor value causes the selection of operating parameters, preferably a nominal generator output power and a peak voltage limit, to suit the selected electrode assembly.

Electrosurgical hand-held battery-operated instrument

Abstract: An electrosurgical instrument comprises a handpiece, a monopolar electrode unit having a single treatment electrode projecting from the handpiece, a radio-frequency generator and a battery within the handpiece for powering the generator. The generator has a single direct radio-frequency output patient connection through the treatment electrode. The return path between the generator and a patient is through an electrically conductive shield around the generator and forming part of the handpiece, the shield forming a capacitive coupling element between the generator and the surroundings. Preferably, the operating frequency of the generator is 5 MHz or greater.

Electrosurgical generator method

Abstract: An electrosurgical system including an electrode assembly having two electrodes for use immersed in an electrically conductive fluid has a generator with control circuitry for rapidly reducing the delivered radio frequency output power by at least 50% within at most a few cycles of the peak radio frequency output voltage reaching a predetermined threshold limit. In this way, tissue coagulation can be performed in, for example, saline without significant steam generation. The same peak voltage limitation technique is used in a tissue vaporization or cutting mode to limit the size of the steam pocket at the electrodes and to avoid electrode burning.

The Life-cycle

Abstract: This chapter is concerned with approaches and techniques used in studying those aspects of parasitoid and predator life cycles that have an important bearing on the major topics covered by other chapters in this book. To illustrate what we mean, consider the female reproductive system of parasitoids which we discuss in some detail (section 2.3). As pointed out by Donaldson and Walter (1988), at least some knowledge of its function/in particular of ovarian dynamics, is crucial to a proper understanding of foraging behaviour in parasitoids. The physiological status of the ovaries may determine: (a) the duration of any preoviposition period following eclosion; (b) the rate of oviposition, (c) the frequency and duration of non-ovipositional activities, e.g. host-feeding; and (d) the insect’s response to external stimuli, e.g. odours, hosts (Collins and Dixon, 1986) (subsection 1.5.1). Note that egg load (defined in subsection 1.2.2) is now being incorporated into foraging models, as it is becoming increasingly clear that certain foraging decisions depend importantly upon the insect’s reproductive state (Jervis and Kidd, 1986; Mangel, 1989a; Chan and Godfray, 1993). It also follows from the above that a female parasitoid’s searching efficiency depends upon the functioning of its reproductive system (subsection 5.3.7), and this may in turn influence parasitoid and host population processes.

Qualitative Data Analysis: Technologies and Representations:

Abstract: In this paper we address a number of contemporary themes concerning the analysis of qualitative data and the ethnographic representation of social realities. A contrast is drawn. On the one hand, a...

Clinical studies of multiple endocrine neoplasia type 1 (MEN1)

Abstract: Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disorder characterized by the combined occurrence of parathyroid, pancreatic islet and anterior pituitary tumours. To facilitate a screening programme for MEN1, we investigated 709 people (364 males and 345 females, age range 1-84 years) from 62 MEN1 families, and 36 non-familial MEN1 patients. Of those investigated, 220 (95 males and 125 females, age range 8-79 years) suffered from MEN1. Parathyroid, pancreatic and pituitary tumours occurred in 95%, 41% and 30% of the patients, respectively. Parathyroid tumours were the first manifestation of MEN1 in 87% of patients, and amongst the pituitary and pancreatic tumours, somatotrophinomas and gastrinomas were more common in patients above the age of 40 years, whilst insulinomas occurred more frequently in patients below the age of 40 years. Biochemical screening indicated that the penetrance of MEN1 by the ages of 20, 35 and 50 years was 43%, 85% and 94%, respectively, and that the development of MEN1 was confined to first-degree relatives in 91% of patients and to second-degree relatives in 9% of patients. These findings have helped to define a proposed screening programme for MEN1.

Determinants of export performance in a European context

Abstract: Drawing attention to certain important gaps in the exporting literature, develops and evaluates a model of export performance using a sample of regular exporters from a small European Union country, in their trading activities with overseas distributors. Integrates and views specific firm characteristics, export commitment and export‐related perception variables as potentially important factors in explaining firm performance in the export market context. Tests the model in a three‐step procedure employing multiple regression analysis and identifies several elements that are related directly to export performance. Discusses the implications of the study for both business practitioners and public policy makers and highlights future research directions.

Features contributing to the growth of ethical consumerism ‐ a preliminary investigation

Abstract: Consumers of the 1990s are claimed to be caring, environmentally and socially aware and are demanding a say in the production, processing and resourcing of the products they regularly purchase. Hypothesizes that the environmentally‐aware consumer has become ethically aware and is joined by many other consumers who believe in the principles of fair trade. The increasingly well‐informed consumer is not only demanding fairly traded products, but is challenging manufacturers and retailers to guarantee the ethical claims they are making about their products. Reports on a survey to investigate the factors contributing to the development of ethical consumerism in the UK, and provides details of the integrating features which it finds. Discusses the implications of these for management.

Knowledge and conscious control of motor actions under stress.

Abstract: A recent study by Masters (1992) investigated the effect of stress upon the performance of a well-learned motor skill, golf putting, acquired under implicit and explicit learning conditions. Masters found that stress had a detrimental effect on performance for the explicit learning group but not for the implicit learning group. However, the implicit learning group was required to perform articulatory suppression during the learning trials but not during the stress trials. As such, it is possible that the subjects in the implicit learning group continued to improve during the stress session simply because they were performing an easier task. This paper reports an experiment which re-examines Masters' (1992) conclusions by replicating and extending his method. An additional implicit learning group was included which was required to carry out articulatory suppression during both the learning trials and the stress trials. It was hypothesized that this ‘new’ implicit learning group would suffer the same disruption to performance as the explicit learning group, providing evidence which would contradict Masters' explanation. Thirty-two subjects were allocated to one of four groups. Performance measures were analysed using two-factor analysis of variance (4 × 5: groups × sessions) with repeated measures on the sessions factor. The main dependent variable was the number of putts successfully completed. The analysis revealed that both the implicit learning groups continued to improve their performance under stress whilst the explicit learning group did not. Despite limitations to both Masters' (1992) and the present study, these results add support to Masters' explicit knowledge hypothesis.

Generator and system for electric operation

Abstract: PROBLEM TO BE SOLVED: To prevent the burning of an electrode and/or excessive tissue evaporation by detecting detection signals for indicating a high frequency peak output voltage appearing at both ends of output connection, driving a switching device connected to a resonance output circuit and reducing supplied high frequency power. SOLUTION: At the time of initially driving this generator, a power switching device for forming the oscillation part of an RF (high frequency) oscillator 60 is switched ON so as to maximize electrically conductive time in respective divergence cycles. When the temperature of fluid inside tissues rises to a level where a fluid medium evaporates and load impedance rapidly increases, an output voltage between output terminals 62 is rapidly increased. Then, when a threshold value is achieved, trigger signals are sent to an ON time control circuit 70 and a switching mode power source 66, the ON time of the switching device is actually instantaneously reduced, a switching mode electrode is simultaneously turned to an impossible state and the voltage supplied to the RF oscillator 60 is lowered.

The biological, social and clinical bases of drug addiction: commentary and debate

Abstract: This article summarizes the main discussions at a meeting on the biological, social and clinical bases of drug addiction focused on contemporary topics in drug dependence. Four main domains are surveyed, reflecting the structure of the meeting: psychological and pharmacological factors; neurobiological substrates; risk factors (including a consideration of vulnerability from an environmental and genetic perspective); and clinical treatment. Among the topics discussed were tolerance, sensitization, withdrawal, craving and relapse; mechanisms of reinforcing actions of drugs at the behavioural, cognitive and neural levels; the role of subjective factors in drug dependence; approaches to the behavioural and molecular genetics of drug dependence; the use of functional neuroimaging; pharmaceutical and psychosocial strategies for treatment; epidemiological and sociological aspects of drug dependence. The survey takes into account the considerable disagreements and controversies arising from the discussions, but also reaches a degree of consensus in certain areas.

Effects of brief counselling among male heavy drinkers identified on general hospital wards.

Abstract: Although the prevalence of heavy alcohol consumption among patients of general hospitals is well documented, no study has yet reported an effect of counselling on the ward in reducing the level of consumption among such patients after discharge. This study was designed to evaluate brief counselling to reduce alcohol consumption among male heavy drinkers identified on general hospital wards. Male patients were screened on wards of four teaching hospitals in Sydney, Australia. Identified heavy drinkers (n = 174) showing predominantly low levels of alcohol dependence were allocated to one of two forms of brief counselling (skills-based counselling or brief motivational interviewing) or to a non-intervention control group. Blind follow-up for 123 patients (71%) was carried out approximately 6 months after discharge from hospital and self-reports of alcohol consumption were compared with collateral sources of information. Patients who received counselling showed a significantly greater mean reduction in a quantity-frequency measure of weekly alcohol consumption than controls but there were no significant differences in reduced consumption between the two intervention groups. However, patients who were deemed "not ready to change" showed greater reductions if they had received brief motivational interviewing than if they had received skills-based counselling. The implications of these findings for counselling male in-patients to reduce alcohol consumption are discussed.

Industrial dynamics modelling of supply chains

Abstract: The use of industrial dynamics modelling of real‐life supply chains has only recently re‐emerged from the shadows after a lengthy gestation period. Shows that it is a powerful methodology for predicting and prioritizing methods of re‐engineering the chain in order to achieve enhanced performance when viewed from the perspective of all “players” in the chain. Building an adequate model of an existing, or proposed, real‐life supply chain requires the use of people‐based sources, observation‐based sources, and systems‐knowledge‐based sources. Illustrates each of these approaches. Concludes with predicting the benefits expected from substantial re‐engineering of an electronics products supply chain.

New Organizational Forms for Competing in Highly Dynamic Environments: the Network Paradigm

Abstract: Turbulence and rapid change in the business environment have been associated for some time with the development of new network organizational forms which put various types of strategic alliance and other inter-organizational collaborations into effect. This paper traces the rationale for the formation of such networks and the associated vertical disaggregation of functions and implications for internal organizational design. This leads to the proposal of a classification framework for network forms. Using the dimensions of volatility of environmental change on the one hand, and the type of inter-organizational relationship involved (collaborative or transactional) on the other hand, network forms are classified as: hollow networks, flexible networks, value-added networks and virtual networks. In each case it is possible to identify the environmental and organizational contingencies most likely to be associated with the emergence and adoption of a particular type of network arrangement. This argument leads to the identification of a new research agenda which has the goals of developing more robust conceptualizations of network characteristics; better understanding the contingencies surrounding the emergence of network forms and their relative efficiencies and specifying some of the major implications of network formation for internal organizational design. In parallel the paper identifies a number of managerial implications for setting strategic priorities and developing appropriate management systems in these new organizational contexts.

Aryl phosphoramidate derivatives of d4T have improved anti-HIV efficacy in tissue culture and may act by the generation of a novel intracellular metabolite

Abstract: New phosphate derivatives of the anti-HIV nucleoside analogue d4T were prepared as potential membrane-soluble prodrugs of the bioactive free nucleotide. The enhanced antiviral potency and/or reduced cytotoxicity of the derivatives leads to an increase in selectivity relative to the parent nucleoside analogue. Moreover, the derivatives appear to bypass the dependence of the nucleoside on thymidine kinase-mediated activation, retaining full activity in thymidine kinase-deficient cells. This strongly suggests the successful intracellular delivery of free nucleotides by the masked phosphate triester prodrugs. This is further confirmed by studies using radiolabeled compound which clearly demonstrate the generation of d4T mono-, di- and triphosphates from the prodrug, even in thymidine kinase-deficient cells. Moreover, we herein report the generation of a new metabolite, a partially hydrolyzed phosphate diester, alaninyl d4T monophosphate. We suggest that at least part of the antiviral action of the prodrugs derives from the intracellular generation of such novel diesters which may add considerable weight to the suggested further preclinical development of the phosphate prodrugs.

The new wave of regional innovation networks: Analysis, characteristics and strategy

Abstract: Today, the number one priority for competitive advantage is innovation. A new approach to regional business development has been pioneered in Europe and the U.S.A. This involves building a regional innovation infrastructure. Learning through “networking” has proven to be a successful approach in some of Europe's more dynamic regional economics such as Baden-Wurttemberg and Emilia-Romagna. This involves maximising the complete range of regional innovation assets. The state of Pennsylvania and other older industry centres are showing that such an approach is transferable from Europe to the U.S.A. The paper assesses knowledge-transfer at the regional level and outlines the key elements for successful regional innovation networking practices. The major finding(s) are that business networking is an effective way of increasing company turnover; that not-for-profit organizations are excellent for setting up networks because they are trusted, and that innovation networks are perhaps the most difficult, thought-requiring but important of the types of business network conceivable.

Time compression and supply chain management ‐ a guided tour

Abstract: Modern supply chains are expected to respond rapidly, effectively and efficiently to changes in the marketplace. Simultaneously there is the drive to achieve world class customer service levels coupled with minimum reasonable inventory (MRI). We thus have the classic conflict of interests between marketing, production and materials management. Marketing wants the complete product range available off‐the‐shelf; production is still, all too often, looking to manufacture in economic batch quantities so as to achieve economies of scale; and materials management is trying to minimize storage and distribution costs which, in turn, requires that a total systems MRI policy be adopted. Time compression at all stages in the chain is seen as the way to respond to these challenges. The ground rules for effective supply chain design were co‐incidentally established in 1961, when Jay Forrester showed that medium period demand amplification was a system dynamics phenomenon which could be tackled by reducing and eliminating delays and the proper design of feedback loops. In the same year, via his “five rules to avoid bankruptcy” directed at smoothing material flow, Burbidge showed that short period demand amplification was due to multi‐phased, multi‐period ordering policies. Confirms that, on the basis of industrial studies, collapsing cycle times drive the business into a more competitive scenario. This means that time compression strategies based on model simulation may be confidently used to predict improvements in supply chain performance.

Autoantibodies to steroidogenic enzymes in autoimmune polyglandular syndrome, Addison's disease, and premature ovarian failure.

Abstract: Autoantibodies to steroidogenic enzymes, steroid 17 alpha-hydroxylase (17 alpha-OH), cytochrome P450 side-chain cleavage enzyme (P450scc), and steroid 21-hydroxylase (21-OH), were measured using specific and sensitive immunoprecipitation assays (IPAs) in patients with various forms of autoimmune adrenal disease. Autoantibodies to 17 alpha-OH were detected in 6 of 11 (55%) patients with autoimmune polyglandular syndrome (APS) type I, 8 of 24 (33%) patients with APS type II, 11 of 56 (20%) patients with adrenal cortex antibody (ACA; measured by immunofluorescence)-positive patients without Addison's disease, and only 3 of 64 (5%) patients with Addison's disease. Autoantibodies to P450scc were found at a prevalence similar to those to 17 alpha-OH: in 5 of 11 (45%) APS type I patients, 10 of 24 (42%) APS type II patients, 11 of 56 (20%) ACA-positive patients without Addison's disease, and only 6 of 64 (9%) patients of the Addison disease group. Autoantibodies to 21-OH were found in a majority of patients with APS type I (7 of 11;64%), APS type II (23 of 24; 96%), Addison's disease (41 of 64; 64%), and ACA-positive patients without Addison's disease (48 of 56; 86%). All sera that were positive for 17 alpha-OH or P450scc were also positive for 21-OH autoantibodies, except in 1 case. There was good agreement between the presence of ACA measured by immunofluorescence and 21-OH antibodies measured by IPA in all patient groups studied, and this indicates that 21-OH is a major autoantigen in adrenal autoimmune disease regardless of whether the disease presents as isolated Addison's disease or APS type I or type II. Autoantibodies to 17 alpha-OH and P450scc appeared to be the major components of the steroid-producing cell antibodies measured by immunofluorescence. No autoantibodies to 21-OH, 17 alpha-OH, or P450scc were detected in 17 sera from patients with premature ovarian failure without evidence of adrenal autoimmunity (as judged by immunofluorescence studies), except for 1 serum in which low levels of 17 alpha-OH antibodies were found. Overall, our studies indicate that 35S-labeled 17 alpha-OH, P450scc, and 21-OH can be used successfully in IPAs for their respective autoantibodies. Assays such as these may well be valuable in the immunological assessment of patients at risk for or suspected of adrenal autoimmunity.

Directionality of Hydrogen Bonds to Sulfur and Oxygen

Abstract: Hydrogen-bonded complexes involving sulfur bases are found to be quite different from the analogous oxygen complexes, both experimentally and in theoretical calculations. In general, hydrogen bonds to sulfur not only are weaker than those to oxygen but also show a marked preference for a more “perpendicular” direction of approach to the donor atom. Ab initio calculations at the MP2/6-311++G(d,p) level on the complexes of hydrogen fluoride with H2O, H2S, H2CO, and H2CS reproduce these differences, as does a search of structures in the Cambridge Crystallographic Data Base. We show that the Laplacian of the charge density ∇2ρ predicts a qualitatively correct structure for all the systems considered, but gives poor quantitative predictions of hydrogen-bonding geometries. An analysis based upon Bader's atoms-in-molecules theory rationalizes the differences between sulfur and oxygen hydrogen bonds. A treatment of the hydrogen bond which explicitly considers the contributions of atomic multipoles to the electros...

Role of wetland plants in the diurnal control of CH4 and CO2 fluxes in peat

Abstract: We demonstrate that a major portion of the microbial activities in peat monoliths are driven by photosynthetic processes and that effluxes of CH4 and CO2 are regulated by the surface vegetation. CH4 and CO2 monitored continuously at a depth of 15 cm and in the headspace above the peat showed oscillatory concentration changes over a 24-h cycle. Comparative anatomy of the vegetative organs of tracheophytes associated with the peat bog revealed the presence of an extensive lacunar system in the roots, rhizomes and leaves of several monocotyledonous species; this provides the path of minimal resistance for gas transport in waterlogged peat.

Populations and Communities

Abstract: In nature, any particular habitat contains animal and plant species which exist together in both time and space. Many of these species will interact with each other, for example when one species feeds on another or when two species compete for the same food or other resource. A group of species having a high degree of spatial and temporal concordance, and in which member species mutually interact to a greater or lesser extent, constitute a community (Askew and Shaw, 1986). The size and complexity of a community will depend upon how broadly that community is defined. For example, we could consider as a community the organisms which interact with each other within a particular area of woodland, the herbivore species which compete for a particular food plant or the complex of natural enemies associated with a particular prey or host species. The animal species of a community obtain their food directly or indirectly from plants which are the primary producers of the community. Herbivores feed directly on plants whilst predators and parasitoids are either primary carnivores, feeding on herbivores, or secondary or tertiary carnivores, feeding on other predators or parasitoids. The successive positions in this feeding hierarchy are termed trophic levels. Thus, green plants occupy the first trophic level, herbivores the second level, carnivores which eat herbivores the third level/secondary carnivores the fourth level, and so on, although a species may occupy more than one level. For example, some insect parasitoids are facultative hyperparasitoids, thus having the potential to occupy two trophic levels. Similarly, some carabid beetles eat both insect prey and plant seeds, and because they are polyphagous predators, the insect prey consumed may consist both of herbivores and of other carnivores.