bluuebunny/crossref_metadata_2025 huggingface dataset:
Competitive positioning and market orientation: two interrelated constructs
Authors: Bigné Enrique , Vila‐López Natalia , Küster‐Boluda Inés
Published: July 2002

Aims to interrelate two lines of research: market orientation and strategic groups identification. Suggests that degree of market orientation of an enterprise should be connected to its competitive strategy and, also, to its final levels of performance. Identifies, in a highly competitive Spanish sector, groups of homogeneous enterprises with regard to their market orientation degree to see if the identified groups differ significantly in the competitive strategy mainly followed by their members and, also, in their economic profile. Uses cluster methodology and the analysis of variance. Also applies multidimensional scaling to visually represent the position of each enterprise in a perceptual space. Recommends some guides to get a market orientation status and also a competitive position in the competitive space.
The right of employees/inventors to claim back their patents from corporations
Authors: Kotorov Radoslav P.
Published: July 2002

Proposes a reform in the intellectual property rights system. The proposed changes give employees/inventors the right to claim back their patents from firms that do not commercialize the patented inventions within a limited period of time. Large corporations commercialize only a fraction of their patent portfolios, and yet the current intellectual property laws do not provide employees/inventors with alternative ways to realize their ideas. The proposed reform empowers nimble employees by providing them with ownership claims against the patent assignees. Ownership claims are considered more effective in empowering employees in an economy where technological and organizational transformation undermine the significance of stakeholder claims.
Innovating in reverse: services and the reverse product cycle
Authors: Gallouj Faïz
Published: July 2002

As they account for the largest share of employment and value added, services do not (or cannot) lie outside a Schumpeterian view of innovation phenomena. Of the various attempts at shedding more light on the mechanisms of innovation in service industries and firms, we consider the “reverse product cycle” to warrant special attention because of its highly thought‐provoking nature and its theoretical ambition. This article has two objectives: first, to present this interesting and still neglected theoretical study, and second, to evaluate on a theoretical and empirical level the extent to which Barras’ model meets the objective of a “theory of innovation in services”.
Internationalization of SMEs: a research note
Authors: Westhead Paul , Binks Martin , Ucbasaran Deniz , Wright Mike
Published: July 2002

In 1990/91, survey responses were gathered from 621 independent businesses located in Great Britain. A follow‐on telephone survey was conducted with 150 surviving firms in 1997. This survey gathered information surrounding the propensity of firms to export their goods or services abroad as well as other performance and goal outcomes. Organizational and external environmental variables collected in 1990 are used to explain within a multivariate statistical framework the propensity of a firm to be an exporter in 1997, and the intensity of internationalization activity. Data collected in 1990 is also used to explain variations in several performance variables (i.e. whether exporting was regarded as a path to firm growth; profit performance reported in 1997 relative to competition; and the propensity to report employment growth over the 1990 to 1997 period).
Knowledge‐based services and the Internet: an investigation of small UK accountancy practices
Authors: Chaston I. , Badger B. , Mangles T. , Sadler‐Smith E.
Published: July 2002

The role of organisational learning in knowledge acquisition for competitive advantage is increasingly found in the literature. Various researchers have used qualitative, single firm case studies to validate a relationship between learning, knowledge and firms exhibiting strong market performance. There is, however, limited empirical evidence on the relative importance of the learning style and management systems required to support the effective marketing of knowledge‐based services. The Internet is an excellent research tool to empirically assess the possible relationships between learning style, knowledge systems and revisions in operational practices. A survey of small UK accountancy practices was undertaken to acquire data on learning style, knowledge systems and market performance. The results and their implications in relation to organisations’ use of the Internet are discussed and proposals are presented for further research.
Leadership in change and the wisdom of a gentleman
Authors: Burdett John O.
Published: July 2002

Resistance to change is a centerpiece in the traditional change agenda. The author argues that resistance to change is not a basic part of our make‐up and he uses the example of his grandfather’s life to provide examples of the many dramatic changes that have successfully impacted on people’s lives during the twentieth century. The author outlines the leadership inadequacies that result in change initiatives being rejected. Central to these leadership problems are a lack of vision, limited integrity, lack of courage, inappropriate language, limited understanding of true empowerment, and only a passing commitment to leadership as service. The argument concludes that while many modern leaders have been trained in the what and the how of change, the real problem lies in the fact that the why and the who gains remains largely mute.
Empowerment in healthcare
Authors: Martin‐Crawford Lisa
Published: July 2002

Explores the trends of health care delivery and how health care workers will need to develop different ways of relating to each other and their clients. These different ways of relating will improve health status and outcomes of clients. The model is described as a way an organization can pursue the strategies to achieving different ways of relating to their clients. The article gives pragmatic ideas about how to begin developing these different relationships.
Investing in Advanced Manufacturing Technology
Authors: Sohal Amrik S.
Published: July 2002

Compares the findings of a survey conducted in Australia and the United
Kingdom which investigated issues concerning investments in advanced
manufacturing technologies (AMTs). Responses were received from 61
companies in Australia (37.9 per cent response rate) and 67 companies in
the United Kingdom (44.7 per cent response rate). Respondents in both
countries represented around ten different industrial sectors and varied
in size from less than 100 employees to more than 10,000 employees.
Respondents reported investment in one or more AMTs with around
two‐thirds of the investment in the range £250,000 to £500,000 and
A$500,000 to A$10m respectively in the two countries. The comparison
shows some interesting similarities and differences between Australia
and the UK. These are in the types of technologies implemented,
financial appraisal methods used, training in AMT and production
management, perceived benefits of AMTs, difficulties of implementing
AMTs and the respondents’ role in formulating various strategies.
Discusses the similarities and differences in the above areas in some
detail and argues why some of the differences exist.
The implementation of total quality management into public sector agencies: a case study of the Tennessee Valley Authority
Authors: Burdette Dean Mary , Helms Marilyn M.
Published: July 2002

Growing foreign competition has encouraged many managers to reappraise traditional management practices. Managers are now realizing that the quality of their products and services must be enhanced to remain competitive in a global market. Many US companies have redirected their company philosophy through the adoption of total quality management (TQM) techniques. TQM has been utilized in the private sector since the mid‐1980s to help struggling US companies recover their profitability. Many governmental agencies have recently decided to implement TQM in their organizations, with hopes that it will have the same effect as it has had in the private sector. The idea of applying TQM principles in the government has resulted because of the overall shift in business philosophy to focusing on customer needs. Outlines the TQM implementation process in a government agency. Tennessee Valley Authority (TVA) is an agency in the government that started the implementation process of TQM in January 1990 as a means of achieving world‐class quality. A strategic quality plan has been developed, and an appropriate infrastructure has been set up to facilitate the implementation process. Also presents how TVA is using the Malcolm Baldrige criteria to guide and measure progress in the implementation and outlines steps followed using a departmental example. Concludes that, based on the TVA success, if the Federal Government does apply TQM, it would have a positive effect on the economy and other business industries.
Competitive priorities, process innovations and time‐based competition in the manufacturing sectors of industrialising economies
Authors: Burgess T.F. , Gules H.K. , Gupta J.N.D. , Tekin M.
Published: July 2002

The topic of competitive priorities has attracted many of those interested in manufacturing strategy and stimulated a number of surveys in manufacturing industry. Much of this empirical work concentrates on large companies in industrialised economies while asserting the general applicability of findings. In contrast the survey reported here was conducted in a newly industrialising country, Turkey, focusing on small to medium‐sized manufacturing enterprises. Key personnel in 41 companies were questioned about the priorities of cost, quality, flexibility and, in particular, time. Process innovations, since these enable improvements in competitive priorities, were also examined. General similarities were evident between the Turkish, other European, and US situations. However, certain elements of quality and time were not ranked as highly in Turkey and the adoption levels of process innovations were lower. In contrast to US data, connections between competitiveness and time‐related performance measures were not apparent. Conclusions were drawn that Turkish manufacturing industry was generally at an earlier, quality‐dependent, stage in developing competitiveness and that time‐based competition was not yet evident.
International property portfolio strategies
Authors: Lizieri Colin , Finlay Louise
Published: July 2002

Formal portfolio selection strategies based on modern portfolio
theory have increasingly been applied to real estate markets, despite
the difficulties posed by the characteristics of property as an
investment asset. As markets have “gone global”, so
portfolio theory has been used to define international property
portfolio strategies. Suggests that many of these studies are flawed, in
that they neglect both methodological developments in portfolio theory
and, critically, the economic fundamentals that drive property markets.
This can lead to the adoption of investment strategies that create
portfolios with a high exposure to risk. Outlines alternative approaches
to global real estate investment.
Modelling the influence of location on value
Authors: Gallimore Paul , Fletcher Michael , Carter Matthew
Published: July 2002

Describes an attempt to predict the value of private properties in the Stafford area from information typically available about the properties’ physical characteristics and location. Discusses the factors influencing property values, including the complicating effect of location, and attempts to build a predictive model using the statistical technique of multiple regression analysis, based on physical characteristics only and ignoring the effect of location. Makes further refinements to the predictions produced by incorporating an additional location effect modelled by means of surface‐fitting techniques within a geographical information system. The results, many of which are presented graphically, are shown to be a significant improvement on the location‐blind model. Offers suggested directions for further research and development of the technique.
Decision theory and real estate investment
Authors: French Nick , French Simon
Published: July 2002

Explains that the focus of decision theory is on
the mathematical models. These may be probability based; loss functions or other forms of
statistical representations of judgements. Yet, much of decision theory does not lie entirely
within any one discipline: it draws on psychology, economics, mathematics, statistics, social
sciences and many other areas of study. Investigates investors’ perceptions and attitudes
towards real estate. Highlights the important difference between theoretical exposure levels and
pragmatic business considerations. Suggests a prescriptive model to explore judgements, beliefs and
preferences of decision makers and to inform decision making. Examines the concept of risk and its
place in developing a prescriptive model. Maintains that a decision must be judged on factors other
than the risk of a single outcome.
How valuers use the value opinions of others
Authors: Diaz Julian , Hansz J. Andrew
Published: July 2002

Theory suggest that valuers will rely on previous values estimates in the face of greater market uncertainty. Nevertheless recent research has provided evidence that experienced real estate valuers (appraisers) working in geographic areas familiar to them may not be influenced by the previous value judgement of other, anonymous experts. Presents a study which extends the previous investigation by examining appraisers valuing property in geographic areas unfamiliar to them, appraisers who therefore face significant market uncertainty. In controlled experiments valuers were asked to appraise a subject property in an area unfamiliar to them and were offered the previous value judgement of an anonymous expert as a potential anchor (reference point). A control group of experts unfamiliar with the subject market was given no reference point whatsoever. Evaluation of the experimental data revealed evidence that unlike subjects operating in areas of familiarity, subjects unfamiliar with the subject area were influenced by the provided reference point.
Neural networks: the prediction of residential values
Authors: McGreal Stanley , Adair Alastair , McBurney Dylan , Patterson David
Published: July 2002

The potential application of data mining techniques in the extraction of information from property data sets is discussed. Particular interest is focused upon neural networks in the valuation of residential property with an evaluation of their ability to predict. Model testing infers a wide variation in the range of outputs with best results for stratified market subsets, using postal code as a locational delimiter. The paper questions whether predicted outcomes are within the range of valuation acceptability and examines issues relating to potential biasing and repeatability of results.
Smart cars and smart insurance: analysing the trends
Authors: Inayatullah Sohail
Published: July 2002

In this article, written as part of a consulting report for the insurance industry, key trends that are likely to impact the motor insurance industry are presented. These trends include: globalization; the rise of the cultural creatives; customization; the rise of the info‐tailor; and ageing. From these trends sketches of three scenarios are presented. These are the great divide; smart cars and smart insurance; and from cars for all to mobility for all.
Setting up a quality costing system
Authors: Dale B.G. , Wan G.M.
Published: July 2002

The paper reports the main findings of an evaluation of four separate quality costing methods which have been trialed in an organisation manufacturing flavourings for the food and drink industry. It was found that the semi‐structured departmental method was the most suitable and a pilot study conducted in a production unit using this method identified 15 non‐conformance cost elements. Among the main findings is that the chosen quality costing method must suit a company’s situation, be based on the concept of continuous improvement, be applicable to all departments and employ a team approach. It is also pointed out that its success will be largely dependent on company culture and the discipline of staff to follow the agreed procedures.
An integrated information system for quality management
Authors: Lari Alireza
Published: July 2002

The current information system use in quality management and ISO 9000 certification process is typically utilized in administration and documentation. The existing software do not satisfy the technical information needs for ISO 9000. There is a need for tools that can help management to decide on technical aspects such as proper corrective and preventive actions or design verification and validation activities. This paper analyzes the information requirements of ISO 9000 standards and identifies the areas where a decision support system can be used. Further, it proposes a conceptual framework for company‐wide information management, while it explains the modular approach to the system development by introducing and empirically testing the prototype model for a corrective and preventive actions module. The proposed system will provide the conceptual structure for a quality assurance information system within organizations.
Critical review of existing BPR methodologies
Authors: Valiris George , Glykas Michalis
Published: July 2002

A plethora of BPR methodologies have appeared in the literature during recent years, however, most of them present serious limitations mainly due to the need for a multi‐disciplinary approach. In this paper we present an overview of existing work in the area of BPR with the aim of highlighting the different categories of BPR methodologies identified in the literature, their focus on the redesign process and the general BPR principles that emerge from them. We also present a BPR methodology called Agent Relationship Morphism Analysis (ARMA) that goes beyond the limitations of the existing BPR methodologies taking a holistic view of the organisation. In ARMA the modelling of the business environment is achieved with the use of three perspectives: the structural, behavioural and process. The use of these three perspectives provides insight to the relationship between organisational structure and organisational processes.
Fuzzy control model in the hospitality industry
Authors: Petrovic‐Lazarevic Sonja , Wong Amy
Published: July 2002

Fuzzy set theory supports business decision‐making processes. So far it has been implemented in many industries, but not in the hospitality industry. An attempt is made to apply general fuzzy control model to service quality processes in the hospitality industry (SQHI). In this respect, the SQHI fuzzy control model is created. The case study underlines a possible practical use of the model in controlling service quality processes in order to achieve or sustain competitive advantage.
Integrated clusters – the future basis of competition
Authors: Carrie Allan
Published: July 2002

As manufacturing becomes a truly global affair, the basis of competition will switch from individual companies and their supply chains to regional clusters. Large multi‐nationals can relocate operations to any part of the world, with significant impact on the regions into and out of which they move. This will introduce new considerations for managers seeking to achieve agile manufacture. In particular, they must recognise the interdependence of all the stakeholders in the economic infrastructure of their part of the world. This contribution discusses the nature of clusters giving some examples. It comments on the role of governmental agencies in economic development.
The development of library client service programs and the role of library consortia
Authors: Hirshon Arnold
Published: July 2002

Librarians today are facing increasing demands for services and stable or declining levels of fiscal and human resources. To survive in an environment of escalating expectations, libraries are looking for new answers as to how they can become more nimble and develop effective strategies and practical solutions. This paper explores two interconnected approaches to solve the riddle[1]. The first approach is to control client expectations by developing and articulating a comprehensive client services program. The second approach is for libraries to work through library consortia not only to expand access to print and electronic collections, but also to develop new services.
An evidence‐based patient information leaflet about otitis media with effusion
Authors: Kubba Haytham
Published: July 2002

Leaflets are a useful resource for information provision. Many otolaryngology patients have poor reading skills, and may have difficulty understanding medical jargon. The aim of this project was to produce a patient information leaflet on otitis media with effusion whose content is based on the best available research evidence, and which is presented in a clear format with simple language. Patients were involved at the planning stage, and in testing the final draft. The leaflet was preferred by the majority compared to existing information material and was felt to be more informative and easier to understand. The leaflet has been given the Crystal Mark for clarity of language by the Plain English Campaign. This study shows that existing guidelines can be used to improve the quality of written information provision.
The alternative media: open sources on what’s real
Authors: Tsang Daniel C.
Published: July 2002

To ignore the alternative press is perilous. The Cold War may have ended, but social protest literature abounds, not just on the Web. Grey political left literature deserves more attention as a counterpoint to the misinformation churned out by the corporate media.
Information and literacy in a time of AIDS: observations of Ethiopia today: a case for grey literature
Authors: Wald Marlena
Published: July 2002

Reviews the poor availability of white literature on AIDS, for use by both health workers and the general public in Ethiopia, as a case for using grey literature to raise awareness.
Teaching the importance of culture and interdisciplinary education for sustainable development
Authors: Eagan Patrick , Cook Tanya , Joeres Erhard
Published: July 2002

Presents a case study of an interdisciplinary, graduate‐level seminar on the topic of international and business sector differences in approaches to sustainable development. The importance of the course is that it mixed culture, business and environmental sciences in a study of sustainability. The pedagogical structure of the course was designed to enable students to learn necessary skills for interdisciplinary, cross‐cultural, and cross‐business sector communication about environmental issues through their participation in the course. Discusses course design specifics and presents results of a student survey about the effectiveness of the course. Overall, students did find participation in the course helpful for improving their ability to communicate about environmental issues across disciplines, cultures, and industries. Students also highlighted several key cultural aspects that contribute to the different ways in which countries and businesses within them respond to environmental issues.
Subject gateway sites and search engine ranking
Authors: Thelwall Mike
Published: July 2002

The spread of subject gateway sites can have an impact on the other major Web information retrieval tool: the commercial search engine. This is because gateway sites perturb the link structure of the Web, something used to rank matches in search engine results pages. The success of Google means that its PageRank algorithm for ranking the importance of Web pages is an object of particular interest, and it is one of the few published ranking algorithms. Although highly mathematical, PageRank admits a simple underlying explanation that allows an analysis of its impact on Web spaces. It is shown that under certain stated assumptions gateway sites can actually decrease the PageRank of their targets. Suggestions are made for gateway site designers and other Web authors to minimise this.
E. coli methionine sulfoxide reductase with a truncated N terminus or C terminus, or both, retains the ability to reduce methionine sulfoxide
Authors: Boschi‐Muller Sandrine , Azza Saïd , Branlant Guy
Published: July 2002

The monomeric peptide methionine sulfoxide reductase (MsrA) catalyzes the irreversible thioredoxin‐dependent reduction of methionine sulfoxide. The crystal structure of MsrAs from Escherichia coli and Bos taurus can be described as a central core of about 140 amino acids that contains the active site. The core is wrapped by two long N‐ and C‐terminal extended chains. The catalytic mechanism of the E. coli enzyme has been recently postulated to take place through formation of a sulfenic acid intermediate, followed by reduction of the intermediate via intrathiol‐disulfide exchanges and thioredoxin oxidation. In the present work, truncated MsrAs at the N‐ or C‐terminal end or at both were produced as folded entities. All forms are able to reduce methionine sulfoxide in the presence of dithiothreitol. However, only the N‐terminal truncated form, which possesses the two cysteines located at the C‐terminus, reduces the sulfenic acid intermediate in a thioredoxin‐dependent manner. The wild type displays a ping‐pong mechanism with either thioredoxin or dithiothreitol as reductant. Kinetic saturation is only observed with thioredoxin with a low KM value of 10 μM. Thus, thioredoxin is likely the reductant in vivo. Truncations do not significantly modify the kinetic properties, except for the double truncated form, which displays a 17‐fold decrease in kcat/KMetSO. Alternative mechanisms for sulfenic acid reduction are also presented based on analysis of available MsrA sequences.
Vagal Regulation and Observed Social Behavior in Infancy
Authors: Stifter Cynthia A. , Corey Janet M.
Published: July 2002

The goal of the present study was to test a recent hypothesis that the ability to suppress cardiac vagal tone during a cognitive challenge was related to social behavior. One hundred thirty‐six infants participated with their parents in laboratory visits when infants were 12 (mother visit) and 13 months (father visit) of age. To measure the infants’ regulation of cardiac vagal tone, heart rate responses were recorded during the administration of a test of mental development (father visit). Responses to a stranger interaction were measured during the 12 month visit. In addition, experimenters evaluated the infants’ behavior across the laboratory sessions using an adaptation of the Infant Behavior Record. Results revealed that infants who were able to suppress vagal tone during the cognitive challenge were rated by the experimenters as more socially approaching at the two laboratory visits. Vagal regulation was unrelated to behavior during the stranger‐infant interaction. These findings partially support the hypothesis that infants who are able to regulate their vagal tone have a greater capacity for social engagement.
Structural analysis of portfolio risk using beta impulse response functions
Authors: Hafner C. M. , Herwartz H.
Published: July 2002

We estimate the data generating process of daily excess returns of 20 major German stocks in a CAPM framework with time varying betas. Our sample spans a 23 year period from 1974 to 1996. An asymmetric dependence of volatility on lagged innovations is taken into account. We introduce beta impulse response functions to shed light on the structural implications of systematic risk associated with competing volatility models. The dependence of beta on news is characterized with respect to different sources (asset specific vs. market general news). The empirical results suggest that negative news emerging from the market involve a stronger impact on beta relative to positive news. Concerning firm specific news the opposite relation is found for the majority of the analysed data sets.
Integrable Shallow‐Water Equations and Undular Bores
Authors: El G. A. , Grimshaw R. H. J. , Pavlov M. V.
Published: July 2002

On the basis of the integrable Kaup–Boussinesq version of the shallow‐water equations, an analytical theory of undular bores is constructed. A complete classification for the problem of the decay of an initial discontinuity is made.
Respiratory‐related activation of human abdominal muscles during exercise
Authors: Abraham Kirk A. , Feingold Howard , Fuller David D. , Jenkins Megan , Mateika Jason H. , Fregosi Ralph F.
Published: July 2002

We tested the hypothesis that abdominal muscles are active during the expiratory phase of the respiratory cycle during exercise. Electromyographic (EMG) activities of external oblique and rectus abdominis muscles were recorded during incremental exercise to exhaustion and during 30 min of constant work rate exercise at an intensity of 85 % of the peak oxygen consumption rate (V̇O2). High amplitude intramuscular EMG activities of both abdominal muscles could be evoked with postural manoeuvres in all subjects. During cycling, respiratory‐related activity of the external obliques was evoked in four of seven subjects, whereas rectus abdominis activity was observed in six of the seven subjects. We measured only the activity that was confined exclusively to the expiratory phase of the respiratory cycle. Expiratory activity of both muscles increased with exercise intensity, although peak values averaged only 10‐20 or 20‐40 % of the peak activity (obtained during maximal, voluntary expiratory efforts) for the external oblique and rectus abdominis muscles, respectively. To estimate how much of the recorded abdominal muscle activity was supporting leg movements during exercise, we compared the activity at the very end of incremental exercise to that recorded during the first five respiratory cycles after the abrupt cessation of exercise, when ventilation was still very high. Although external oblique activity was reduced after exercise stopped, clear expiratory activity remained. Rectus abdominis activity remained high after exercise cessation, showing a gradual decline that approximated the decline in ventilation. During constant work rate exercise, EMG activities increased to 40‐50 and 5‐10 % of peak in rectus and external oblique muscles, respectively, and then plateaued for the remainder of the bout in spite of a continual upward drift in V̇O2 and pulmonary ventilation. Linear regression analysis showed that the rise in respiratory‐related expiratory muscle activity during progressive intensity exercise was significantly correlated with ventilation, although weakly. In constant work rate exercise, expiratory EMG activities increased, but the changes were highly variable and did not change as a function of exercise time, even though ventilation drifted significantly with time. These experiments suggest that abdominal muscles play a role in regulating the ventilatory response to progressive intensity bicycle exercise, although some of the observed activity may support postural adjustments or limb movements. The contribution of abdominal muscles to ventilation during constant work rate exercise is variable, and expiratory activity does not ‘drift’ significantly with time.
Differential presynaptic inhibition of actions of group II afferents in di‐ and polysynaptic pathways to feline motoneurones
Authors: Jankowska E. , Slawinska U. , Hammar I.
Published: July 2002

The aim of this study was to investigate differences in the effects of presynaptic inhibition of transmission from group II muscle afferents to neurones in the dorsal horn and in the intermediate zone and the consequences of these differences for reflex actions of group II afferents upon α‐motoneurones. The degree of presynaptic inhibition was estimated from the degree of depression of monosynaptic components of population EPSPs (field potentials) evoked by group II muscle afferents in deeply anaesthetized cats. The decrease in the area of field potentials was considerably larger and longer lasting in the intermediate zone, where they were often obliterated, than in the dorsal horn, where they were reduced to about two‐thirds. Presynaptic inhibition of field potentials evoked by other afferents at the same locations was much weaker. Intracellular records from α‐motoneurones revealed that short latency EPSPs and IPSPs evoked from group II afferents are considerably reduced by conditioning stimuli that effectively depress intermediate zone field potentials of group II origin. The results of this study lead to the conclusion that strong presynaptic inhibition of transmission to intermediate zone interneurones allows a selective depression of disynaptic actions of group II muscle afferents on α‐ and γ‐motoneurones, mediated by these interneurones, and favours polysynaptic actions of these afferents.
Determination of alveolar epithelial cell phenotypes in fetal sheep: evidence for the involvement of basal lung expansion
Authors: Flecknoe Sharon J. , Wallace Megan J. , Harding Richard , Hooper Stuart B.
Published: July 2002

The factors that control the differentiation of alveolar epithelial cells (AECs) into type‐I and type‐II cells in vivo are largely unknown. As sustained increases in fetal lung expansion induce type‐II AECs to differentiate into type‐I cells, our aim was to determine whether reduced fetal lung expansion can induce type‐I AECs to trans‐differentiate into type‐II AECs. Chronically catheterised fetal sheep were divided into two age‐matched control groups and three experimental groups (n= 5 for each). The experimental groups were exposed to either: (1) 10 days of increased lung expansion induced by tracheal obstruction (TO), (2) 10 days of TO followed by 5 days of reduced lung expansion induced by lung liquid drainage (LLD), or (3) 10 days of TO followed by 10 days of LLD. Following 10 days of TO, 5 days of LLD reduced the proportion of type‐I AECs from 89.4 ± 0.9 % to 68.4 ± 2.8 %, which was similar to control values (64.8 ± 0.5 %), and increased the proportion of type‐II AECs from 1.9 ± 0.3 % to 21.9 ± 2.8 %, which remained below control values (33.4 ± 1.7 %). The same treatment increased surfactant protein (SP)‐A, SP‐B and SP‐C mRNA levels (expressed as a percentage of control values) from 26.7 ± 6.0 %, 40.0 ± 7.3 % and 10.3 ± 1.8 % to 78.1 ± 10.3 %, 105.8 ± 12.7 % and 121.0 ± 14.1 %, respectively. Similar results were obtained after 10 days of LLD, which followed 10 days of TO. These results indicate that the phenotypes of type‐I and type‐II AECs are strongly influenced by the basal degree of lung expansion in fetal sheep. Furthermore, the coincident increase in type‐II AEC proportions and SP mRNA levels in response to LLD suggests that type‐I AECs can trans‐differentiate into functional type‐II cells, and hence are not terminally differentiated.
Short‐term synaptic plasticity, simulation of nerve terminal dynamics, and the effects of protein kinase C activation in rat hippocampus
Authors: Brager Darrin H. , Capogna Marco , Thompson Scott M.
Published: July 2002

Phorbol esters are hypothesised to produce a protein kinase C (PKC)‐dependent increase in the probability of transmitter release via two mechanisms: facilitation of vesicle fusion or increases in synaptic vesicle number and replenishment. We used a combination of electrophysiology and computer simulation to distinguish these possibilities. We constructed a stochastic model of the presynaptic contacts between a pair of hippocampal pyramidal cells that used biologically realistic processes and was constrained by electrophysiological data. The model reproduced faithfully several forms of short‐term synaptic plasticity, including short‐term synaptic depression (STD), and allowed us to manipulate several experimentally inaccessible processes. Simulation of an increase in the size of the readily releasable vesicle pool and the time of vesicle replenishment decreased STD, whereas simulation of a facilitation of vesicle fusion downstream of Ca2+ influx enhanced STD. Because activation of protein kinase C with phorbol ester enhanced STD of EPSCs in rat hippocampal slice cultures, we conclude that an increase in the sensitivity of the release process for Ca2+ underlies the potentiation of neurotransmitter release by PKC.
Fast network oscillations induced by potassium transients in the rat hippocampus in vitro
Authors: LeBeau Fiona E. N. , Towers Stephen K. , Traub Roger D. , Whittington Miles A. , Buhl Eberhard H.
Published: July 2002

Brief pressure ejection of solutions containing potassium, caesium or rubidium ions into stratum radiatum of the CA1 or CA3 regions of the hippocampal slice evoked a fast network oscillation. The activity evoked lasted ∼3–25 s with the predominant frequency component being in the gamma frequency range (30–80 Hz), although beta frequency (15–30 Hz) and ultrafast (> 80 Hz) components could also be seen. The gamma frequency component of the oscillation remained constant, even when large changes in power occurred, and was synchronous across the CA1 region. Measurements with potassium ion‐sensitive electrodes revealed that the network oscillation was accompanied by increases (0.5 to 2.0 mm) in the extracellular potassium concentration [K+]o. Bath application of the N‐methyl‐d‐aspartate (NMDA) receptor antagonists d(–)‐2‐amino‐5‐phosphonopentanoic acid (d‐AP5; 50 μM) had no significant effect but the α‐amino‐3‐hydroxy‐5‐methyl‐4‐isooxazolepropionic acid (AMPA)/kainate receptor antagonist 2,3,‐dioxo‐6‐nitro‐1,2,3,4‐tetrahydrobenzo[f]quinoxaline‐7‐sulphonamide disodium (NBQX; 20 μM) caused a significant reduction (86.7 ± 4.5 %) in the power in the gamma frequency range. Residual rhythmic activity, presumably arising in the interneuronal network, was blocked by the GABAA receptor antagonist bicuculline. The putative gap junction blocker octanol caused a decrease in the power of the gamma frequency component of 75.5 ± 5.6 %, while carbenoxolone produced a reduction of only 14 ± 42 %. These experiments demonstrate that a modest increase in exogenous [K+]o in the hippocampus in vitro is sufficient to evoke a fast network oscillation, which is an emergent property of the synaptically and electrically interconnected neuronal network.
Pre‐ and postsynaptic ATP‐sensitive potassium channels during metabolic inhibition of rat hippocampal CA1 neurons
Authors: Matsumoto Nozomu , Komiyama Sohtaro , Akaike Norio
Published: July 2002

Presynaptic and postsynaptic membrane activities during experimental metabolic inhibition were analysed in mechanically dissociated rat hippocampal neurons using nystatin‐perforated and conventional whole‐cell patch clamp recordings. NaCN, an inhibitor of mitochondrial ATP synthesis, induced an outward current across the postsynaptic soma membrane. This current was blocked by tolbutamide, a sulfonylurea, which blocks ATP‐sensitive K+ (KATP) channels. The presynaptic effect of metabolic inhibitors such as NaCN, NaN3, or glucose‐free solution was to increase the frequency of GABAergic miniature inhibitory postsynaptic currents (mIPSCs). Tolbutamide had no effect on this increase in mIPSC frequency induced by metabolic inhibition. Diazoxide, a KATP channel opener, evoked a similar somatic outward current in a dose‐dependent manner. In addition, diazoxide decreased the frequency of mIPSCs in a dose‐dependent fashion. Both these pre‐ and postsynaptic effects of diazoxide were reversed by tolbutamide, suggesting the existence of KATP channels on both pre‐ and postsynaptic membranes. These results confirm the presence of KATP channels on both the pre‐ and postsynaptic membranes but indicate that the channels have significantly different sensitivities to metabolic inhibition.
Voltage‐dependent inward currents of interstitial cells of Cajal from murine colon and small intestine
Authors: Chul Kim Young , Don Koh Sang , Sanders Kenton M.
Published: July 2002

Electrical slow waves in gastrointestinal (GI) muscles are generated by pacemaker cells, known as interstitial cells of Cajal (ICC). The pacemaker conductance is regulated by periodic release of Ca2+ from inositol 1,4,5‐trisphosphate (IP3) receptor‐operated stores, but little is known about how slow waves are actively propagated. We investigated voltage‐dependent Ca2+ currents in cultured ICC from the murine colon and small intestine. ICC, identified by kit immunohistochemistry, were spontaneously active under current clamp and generated transient inward (pacemaker) currents under voltage clamp. Depolarization activated inward currents due to entry of Ca2+. Nicardipine (1 μM) blocked only half of the voltage‐dependent inward current. After nicardipine, there was a shift in the potential at which peak current was obtained (‐15 mV), and negative shifts in the voltage dependence of activation and inactivation of the remaining voltage‐dependent inward current. The current that was resistant to dihydropyridine (IVDDR) displayed kinetics, ion selectivity and pharmacology that differed from dihydropyridine‐sensitive Ca2+ currents. IVDDR was increased by elevating extracellular Ca2+ from 2 to 10 mm, and this caused a +30 mV shift in reversal potential. IVDDR was blocked by Ni2+ (100 μM) or mebefradil (1 μM) but was not affected by blockers of N‐, P‐ or Q‐type Ca2+ channels. Equimolar replacement of Ca2+ with Ba2+ reduced IVDDR without effects on inactivation kinetics. BayK8644 had significantly less effect on IVDDR than on IVDIC. In summary, two components of inward Ca2+ current were resolved in ICC of murine small intestine and colon. Since slow waves persist in the presence of dihydropyridines, the dyhydropyridine‐resistant component of inward current may contribute to slow wave propagation.
Synchronized oscillations caused by disinhibition in rodent neocortex are generated by recurrent synaptic activity mediated by AMPA receptors
Authors: Castro‐Alamancos Manuel A. , Rigas Pavlos
Published: July 2002

During disinhibition the neocortex generates synchronous activities. In neocortical slices application of GABAA and GABAB receptor antagonists transformed slow oscillations into large amplitude spike‐wave discharges that contained a rhythmic ∼10 Hz neocortical oscillation. The 10 Hz oscillations caused by disinhibition were highly region specific and were generated only in frontal agranular regions of neocortex, such as the primary motor cortex, but not in granular neocortex. Pharmacological manipulations showed that the 10 Hz oscillations were critically dependent on α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionate (AMPA) receptors. Current source density (CSD) analyses in slices using 16‐site silicon probes revealed that the 10 Hz oscillations were expressed with large current sinks in the upper layers and smaller current sinks in the lower layers that precede them. The results indicate that blocking GABAB receptors in the agranular neocortex unmasks recurrent synaptic activity mediated by AMPA receptors that results in the generation of these oscillations.
Melanin‐concentrating hormone depresses L‐, N‐, and P/Q‐type voltage‐dependent calcium channels in rat lateral hypothalamic neurons
Authors: Gao Xiao‐Bing , van den Pol Anthony N.
Published: July 2002

Melanin‐concentrating hormone (MCH), a cyclic 19‐amino‐acid peptide, is synthesized exclusively by neurons in the lateral hypothalamic (LH) area. It is involved in a number of brain functions and recently has raised interest because of its role in energy homeostasis. MCH axons and receptors are found throughout the brain. Previous reports set the foundation for understanding the cellular actions of MCH by using non‐neuronal cells transfected with the MCH receptor gene; these cells exhibited an increase in cytoplasmic calcium in response to MCH, suggesting an excitatory action for the peptide. In the study presented here, we have used whole‐cell recording in 117 neurons from LH cultures and brain slices to examine the actions of MCH. MCH decreased the amplitude of voltage‐dependent calcium currents in almost all tested neurons. The inhibition desensitized rapidly (18 s to half maximum at 100 nm concentration) and was dose‐dependent (IC50= 7.8 nm) when activated with a pulse from –80 mV to 0 mV. A priori activation of G‐proteins with GTPγS completely eliminated the MCH‐induced effect at low MCH concentrations and reduced the MCH‐induced effect at high MCH concentrations. Inhibition of G‐proteins with pertussis toxin (PTX) blocked the MCH‐induced inhibitory effect at high MCH concentrations. Pre‐pulse depolarization resulted in an attenuation of the MCH‐induced inhibition of calcium currents in most neurons. These data suggest that MCH exerts an inhibitory effect on calcium currents via PTX‐sensitive G‐protein pathways, probably the Gi/Go pathway, in LH neurons. L‐, N‐ and P/Q‐type calcium channels were identified in LH neurons, with L‐ and N‐type channels accounting for most of the voltage‐activated current (about 40 % each); MCH attenuated each of the three types (mean 50 % depression), with the greatest inhibition found for N‐type currents. In contrast to previous data on non‐neuronal cells showing an MHC‐evoked increase in calcium, our data suggest that the reverse occurs in LH neurons. The attenuation of calcium currents is consistent with an inhibitory action for the peptide in neurons.
Potentiation of ‘on’ bipolar cell flash responses by dim background light and cGMP in dogfish retinal slices
Authors: Shiells R. A. , Falk G.
Published: July 2002

The high sensitivity of the vertebrate visual system results from amplification inherent in phototransduction in rods and from the amplification of rod signals on their synaptic transfer at the first synapse with ‘on’ bipolar cells. These cells possess a metabotropic glutamate receptor linked via a cGMP cascade to the control of cGMP‐activated channels. In the study presented here, we show that very dim background light, isomerising only one rhodopsin in 1 out of 10 rods per second, potentiates ‘on’ bipolar cell responses to superimposed flashes. Responses to dim flashes, which were undetectable above the noise in the dark, were boosted above the increased noise level induced by the background. This potentiation could be reproduced by elevating cGMP, which increases with light, or by dialysing the cells with a non‐hydrolysable cGMP analogue. Inhibition of tyrosine kinase activity also reproduced the effect and induced a speeding up of the rising phase of the flash response, similar to the action of dim background light. Conversely, inhibition of tyrosine phosphatase activity blocked the potentiation. These results suggest that cGMP promotes tyrosine‐site dephosphorylation of ‘on’ bipolar cell cGMP‐activated channels, resulting in a rise in the sensitivity to cGMP, as has recently been demonstrated for rod cGMP‐activated channels. This constitutes a positive feedback mechanism such that as cGMP increases with light, the sensitivity of the channels to cGMP increases and boosts the signal above background noise. This mechanism would allow stochastic resonance to occur, facilitating single‐photon detection when dark‐adapted, and may therefore lead to improved discrimination.