bluuebunny/crossref_metadata_2025_split huggingface dataset:
Promiscuous gene expression and the developmental dynamics of medullary thymic epithelial cells
Authors: Gäbler Jana , Arnold Janna , Kyewski Bruno 
Published: November 2007

AbstractThymic epithelial cells (TEC) form the structural and functional microenvironment necessary for the establishment and quality control of the T cell repertoire. In addition, they provide an ectopic source of numerous tissue‐restricted antigens (TRA), a feature called promiscuous gene expression (pGE). How the regulation of pGE is related to the cell biology of TEC subset(s), e.g. their turnover and developmental interrelationship is still poorly understood. The observation that pGE is foremost a property of phenotypically and functionally mature medullary TEC (mTEC) implies that the full implementation of pGE is contingent on mTEC differentiation. Here, we show that the emergence of TEC subsets and pGE is tightly correlated during ontogeny and we provide evidence that mature CD80pos mTEC develop from an immature CD80neg subset. This differentiation step proceeds continuously in the postnatal thymus. While mature mTEC turnover in 2 to 3 weeks, immature mTEC encompass a smaller cycling and a larger non‐cycling pool. The latter might serve as a reservoir of committed precursors, which sustain this renewal process. Our data document that mTEC represent a highly dynamic cell population, and they imply that the availability and display of TRA in the thymus undergoes a perpetual temporal and spatial reorganization.
Induction and protective role of antibodies in Legionella pneumophila infection
Authors: Joller Nicole , Spörri Roman , Hilbi Hubert , Oxenius Annette 
Published: November 2007

AbstractLegionella pneumophila (Lpn) is a ubiquitous Gram‐negative bacterium found in aquatic environments and is the causative agent of Legionnaires’ disease, a severe form of pneumonia. We have used Lpn‐permissive A/J mice as a model to analyze the B cell response upon intravenous (i.v.) and intranasal (i.n.) infection with Lpn. A strong antibody (Ab) response was observed upon i.v. infection with wild‐type (WT) Lpn and an icmT mutant strain, which is unable to replicate within permissive host cells. In contrast to i.v. infection, only WT but not icmT mutant Lpn was able to induce specific Ab responses upon i.n. infection. After primary i.n. infection with WT Lpn, a strict compartmentalization of Lpn‐specific Ab isotypes was observed, as IgG was found exclusively systemically, while IgA was detectable only locally in the lung. Regardless of the infection route, isotype switching to IgG and to IgA was strictly dependent on CD4+ T cells, whereas IgM production was completely Th‐independent. Finally, we analyzed the protective capacity of the Lpn‐specific Ab response. Actively or passively immunized mice or mice that were infected with opsonized Lpn had 50–100‐fold reduced bacterial titers compared to naive animals, clearly demonstrating the capacity of Ab to protect against infection with Lpn.
Innate responses of B cells
Authors: Gray David , Gray Mohini , Barr Tom 
Published: November 2007

AbstractIn this review, we describe the non‐antibody‐mediated functions of B cells within the immune system. In addition to antibody production, B cells also present antigen to T cells, programme T cell differentiation and regulate effector T cell responses and much of this is mediated by the cytokines they make. We focus on the potential of B cells to perform these functions simply as a result of activation via ‘innate’ receptors (e.g. Toll‐like receptors) and often independently of BCR ligation. We feel an appreciation of these broad and often antigen‐nonspecific functions is important at a time when there is an increasing use of B cell depletion as a therapy for autoimmune disease.
Mapping immune response profiles: The emerging scenario from helminth immunology
Authors: Díaz Alvaro , Allen Judith E. 
Published: November 2007

AbstractMetazoan parasites of mammals (helminths) belong to highly divergent animal groups and yet induce a stereotypical host response: Th2‐type immunity. It has long been debated whether this response benefits the host or the parasite. We review the current literature and suggest that Th2 immunity is an evolutionarily appropriate response to metazoan invaders both in terms of controlling parasites and repairing the damage they inflict. However, successful parasites induce regulatory responses, which become superimposed with, and control, Th2 responses. Beyond helminth infection, this superimposition of response profiles may be the norm: both Th1 and Th2 responses coexist with regulatory responses or, on the contrary, with the inflammatory Th17 responses. Thus, typical responses to helminth infections may differ from Th2‐dominated allergic reactions in featuring not only a stronger regulatory component but also a weaker Th17 component. The similarity of immune response profiles to phylogenetically distinct helminths probably arises from mammalian evolution having hard‐wired diverse worm molecules, plus tissue‐damage signals, to the beneficial Th2 response, and from the convergent evolution of different helminths to elicit regulatory responses. We speculate that initiation of both Th2 and regulatory responses involves combinatorial signaling, whereby TLR‐mediated signals are modulated by signals from other innate receptors, including lectins.
Electroactive intercalators for DNA analysis on microchip electrophoresis
Authors: Castaño‐Álvarez Mario , Fernández‐Abedul M. Teresa , Costa‐García Agustín 
Published: November 2007

AbstractMiniaturized analytical systems, especially microchip CE (MCE), are becoming a promising tool for analytical purposes including DNA analysis. These microdevices require a sensitive and miniaturizable detection system such as electrochemical detection (ED). Several electroactive DNA intercalators, including the organic dye methylene blue (MB), anthraquinone derivatives, and the metal complexes Fe(phen)32+ and Ru(phen)32+, have been tested for using in combination with thermoplastic olefin polymer of amorphous structure (Topas) CE‐microchips and ED. Two end‐channel approaches for integration of gold wire electrodes in CE‐ED microchip were used. A 250 μm diameter gold wire was manually aligned at the outlet of the separation channel. A new approach based on a guide channel for integration of 100 and 50 μm diameter gold wire has been also developed in order to reduce the background current and the baseline noise level. Modification of gold wire electrodes has been also tested to improve the detector performance. Application of MCE‐ED for ssDNA detection has been studied and demonstrated for the first time using the electroactive dye MB. Electrostatic interaction between cationic MB and anionic ssDNA was used for monitoring the DNA on microchips. Thus, reproducible calibration curves for ssDNA were obtained. This study advances the feasibility of direct DNA analysis using CE‐microchip with ED.
Property of ionic liquid in electrophoresis and its application in chiral separation on microchips
Authors: Zeng Hu‐Lie , Shen Hui , Nakagama Tatsuro , Uchiyama Katsumi 
Published: November 2007

AbstractThe aqueous solution of a kind of room‐temperature ionic liquids (RTILs), 1‐ethyl‐3‐methylimidazolium‐tetrafluoroborate (1E‐3MI‐TFB), demonstrated its exclusive electroosmotic property in microchip electrophoresis. It was applied as the working electrolyte for chiral separation in glass microchip electrophoresis. Compared with boric acid buffer, 1E‐3MI‐TFB aqueous solution exhibited a broader separation window for enantiomers of dipeptides. Then the influences of chiral selector, pH and concentration on efficiency of chiral separation were discussed in detail. The unique mechanism of the generation of EOF was explored in a glass microchannel using 1E‐3MI‐TFB aqueous solution as working electrolyte. A possible status of 1E‐3MI cation in water was suggested at the first time, which facilitated the explanation of EOF and its characteristics in glass microchannel. Additionally, microchip electrophoresis using 1E‐3MI‐TFB aqueous solution was successfully applied to the chiral separation of complex enantiomers of dipeptides. RTILs aqueous solution, as the electrolyte for the separation of complicated optical isomers, could lead to a revolution in the analytical methods of chiral or conformational analysis for biomolecules.
Restoring capability of bilinear hysteretic seismic isolation systems
Authors: Katsaras Christos P. , Panagiotakos Telemachos B. , Kolias Basil 
Published: November 2007

AbstractThe restoring capability (or re‐centering capability) is identified by the current design codes as a fundamental feature of seismic isolation systems. In this paper, the restoring capability of bilinear hysteretic or frictional seismic isolation systems is investigated in some detail. Certain energy considerations are examined first in order to provide insight into and reveal governing parameters on individual aspects of the problem. The restoring capability is then investigated through an extensive parametric study of smooth bilinear single‐degree‐of‐freedom hysteretic systems, with parameters covering a range of typical seismic isolation systems, subjected to a large group of recorded earthquakes. The results of the parametric analyses are processed statistically and regression analysis relations are derived that show the dependence of the residual displacement after the earthquake and the cumulative build up of displacements after a series of successive earthquakes on the governing parameters. Based on the analysis results, the features of the bilinear system that ensure sufficient restoring capability are identified. Copyright © 2007 John Wiley & Sons, Ltd.
The extended switching regression model: allowing for multiple latent state variables
Authors: Preminger Arie , Ben‐zion Uri , Wettstein David 
Published: November 2007

AbstractIn this paper we extend the widely followed approach of switching regression models, i.e. models in which the parameters are determined by a latent discrete state variable. We construct a model with several latent state variables, where the model parameters are partitioned into disjoint groups, each one of which is independently determined by a corresponding state variable. Such a model is called an extended switching regression (ESR) model. We develop an EM algorithm to estimate the model parameters, and discuss the consistency and asymptotic normality of the maximum likelihood estimates. Finally, we use the ESR model to combine volatility forecasts of foreign exchange rates. The resulting forecast combination using the ESR model tends to dominate those generated by traditional procedures.  Copyright © 2007 John Wiley & Sons, Ltd.
Evaluation of correlation forecasting models for risk management
Authors: Skintzi Vasiliki D. , Xanthopoulos‐Sisinis Spyros 
Published: November 2007

AbstractReliable correlation forecasts are of paramount importance in modern risk management systems. A plethora of correlation forecasting models have been proposed in the open literature, yet their impact on the accuracy of value‐at‐risk calculations has not been explicitly investigated. In this paper, traditional and modern correlation forecasting techniques are compared using standard statistical and risk management loss functions. Three portfolios consisting of stocks, bonds and currencies are considered. We find that GARCH models can better account for the correlation's dynamic structure in the stock and bond portfolios. On the other hand, simpler specifications such as the historical mean model or simple moving average models are better suited for the currency portfolio.  Copyright © 2007 John Wiley & Sons, Ltd.
Plasma Sputtering Deposition of PEMFC Porous Carbon Platinum Electrodes
Authors: Rabat H. , Brault P. 
Published: November 2007

AbstractA novel method is proposed to fabricate the active catalytic layers of proton exchange membrane fuel cells (PEMFC). A plasma sputtering technique is used to deposit a porous columnar carbon film (column diameter of 20 nm) followed by the catalyst (platinum) deposition directly on the proton‐conducting membrane. The study of Pt diffusion shows that the optimised catalysed layers correspond to low plasma pressure operation (0.5 Pa) below a platinum loading limit of about 90 μg cm–2. The initial carbon porosity is then maintained and Pt nanoparticles are present in all parts of the carbon layer. A membrane electrode assembly (MEA) is then achieved by alternate depositions of carbon and platinum onto both sides of the membrane. The results show the importance of the porous carbon structure. A significant increase in the catalyst efficiency is observed compared to a commercial fuel cell when measuring open circuit voltage.
Transplanted astrocytes internalize deposited β‐amyloid peptides in a transgenic mouse model of Alzheimer's disease
Authors: Pihlaja Rea , Koistinaho Jari , Malm Tarja , Sikkilä Herkko , Vainio Seppo , Koistinaho Milla 
Published: November 2007

AbstractAlzheimer's disease (AD) is one of the most devastating neurodegenerative disorders. The neuropathological hallmarks include extracellular senile plaques consisting of deposited β‐amyloid (Aβ) peptides and intraneuronal neurofibrillary tangles. Neuroinflammation and activation of astrocytes are also well‐established features of AD neuropathology; however, the relationships between astrocytes and Aβ deposition remain unclear. Previous studies have shown that adult mouse astrocytes internalize and degrade Aβ deposits in brain sections prepared from human amyloid precursor protein (APP) transgenic mice. In the present study, we demonstrate that cultured adult, but not neonatal mouse astrocytes, respond morphologically and degrade Aβ deposits present in human AD brain. We also transplanted astrocytes isolated from enhanced green fluorescent protein expressing adult and neonatal mice into the hippocampi of human Aβ plaque‐bearing transgenic APPSwe+PS1dE9 (APdE9) mice and their wild‐type littermates and followed the migration and localization of these astrocytes by confocal microscopy upto 7 days after transplantation. Posttransplantation the astrocytes localized as aggregates or thin strings of many cells within the hippocampi of APdE9 and wild‐type mice and showed limited migration from the injection site. Interestingly, most of the transplanted astrocytes were found near Aβ deposits in the hippocampi of APdE9 mice. In contrast to findings in ex vivo degradation assay, confocal microscopy revealed that both adult and neonatal transplanted astrocytes internalized human Aβ immunoreactive material in vivo. These results support the role of astrocytes as active Aβ clearing cells in the CNS that may have important implications for future development of therapeutic strategies for AD. © 2007 Wiley‐Liss, Inc.
Do family caregivers perceive more difficulty when they look after patients with early onset dementia compared to those with late onset dementia?
Authors: Arai Asuna , Matsumoto Teruhisa , Ikeda Manabu , Arai Yumiko 
Published: November 2007

AbstractObjectiveTo compare family caregiving situations for patients with early onset dementia (EOD) and late onset dementia (LOD), and to identify the specific problems experienced by relatives caring for EOD patients.MethodsThe participants were chosen from 92 consecutive caregiver–patient dyads, comprising co‐residing family caregivers and outpatients who fulfilled the diagnostic criteria for dementia. The patients were assessed according to cognitive function, neuropsychiatric disturbances and the severity of dementia. The caregivers completed a self‐administered questionnaire that included items on their sociodemographic status and caregiving situation. Caregiver burden was assessed by the Japanese version of the Zarit Burden Interview.ResultsIn total, 68 dyads were eligible for the analysis, 14 of which included patients with EOD and 54 of which included patients with LOD. There were no significant differences between the two groups in terms of patient clinical features, duration of caregiving, number of hours during which caregivers were relieved per day or number of hours of caregiving per day. No significant associations were detected between the type of dementia and caregiver characteristics (such as health status) or caregiver burden, even after adjusting for confounding variables. However, the caregivers of EOD patients had greater perceived difficulties due to patient behavioural disturbances than did the caregivers of LOD patients.ConclusionsOur findings demonstrated that additional resources, such as care services, should be provided for sufferers of EOD, in order to allow family caregivers to cope with difficulties associated with patient behavioural problems. Copyright © 2007 John Wiley & Sons, Ltd.
Out‐of‐pocket payment for medical care under Taiwan's National Health Insurance system
Authors: Chi Chunhuei , Lee Jwo‐Leun , Tsai Shu‐Ling , Chen Wen‐Yi 
Published: November 2007

AbstractThe objective of this study is to estimate the amount of and factors associated with out‐of‐pocket (OOP) payment for medical care under Taiwan's National Health Insurance (NHI) program. This research used two methods to collect original data. The first method consisted of using a sample household survey and household diary records to collect data on OOP payment prospectively over a two‐month period from a random sample of 600 households in central Taiwan. Using the individual as the unit of analysis, we obtained a total of 1062 sample subjects. To ascertain the quality and accuracy of survey data, the claim records of the bureau of NHI were merged with the survey data. These data were analyzed by a two‐part model, with a probit model for use of health care and an ordinary least‐squares model for OOP payments. Results of this research indicate that on average an individual's annual OOP payment for medical care was € 247, which is substantial, compared with the average € 144 for per capita NHI earmarked tax. Finally, results of model estimation indicate that supplemental health insurance and household income were positively associated with any use of health care, while household income was also positively associated with OOP payment for health care. Copyright © 2007 John Wiley & Sons, Ltd.
Equity, governance and financing after health care reform: lessons from Mexico
Authors: Arredondo Armando , Orozco Emanuel 
Published: November 2007

AbstractTo determine, from the perspective of providers, community leaders and users of health services, equity, governance and health financing outcomes of the Mexican health system reform.Cross‐sectional study oriented towards the qualitative analysis of financing, governance and equity indicators for the uninsured population. Taking into account feasibility, as well as political and technical criteria, six Mexican states were selected as study populations and a qualitative research was conducted during 2004–2006. Two hundred and forty in‐depth interviews were applied, in all selected states, to 60 decision‐makers, including medical and administrative personnel; 60 service providers at health centres; 60 representatives of civil organizations, including municipal representatives and, finally, 60 members of health committees and users of services at second and first levels of care units. The analysis of interviews was performed using ATLAS‐Ti software. An outcome mapping of health reform was developed.For political actors, Mexican health system reform has not modified dependence on the central level; ignorance about reform strategies and lack of participation in the search for financial resources to finance health systems were evidenced. Also, in all states under study, community leaders and users of services reported the need to improve an effective accountability system at both municipal and state levels. Health strategies for equity, governance and financing do not have adequate mechanisms to promote participation from all social actors. Improving this situation is a very important goal in the Mexican health democratization process, in the context of health care reform. There are relevant positive and negative effects of the reform on equity, governance and financing in health. Special emphasis is placed on the analysis of lessons learned in Mexico and the usefulness of the main strengths and weaknesses, as relevant evidences for other middle‐income countries which are designing, implementing and evaluating reform strategies in order to achieve equity in resource allocation, good levels of governance and a greater financial protection in health. Copyright © 2007 John Wiley & Sons, Ltd.
Exchange rates and product variety
Authors: Simbanegavi Witness 
Published: November 2007

AbstractWe study the role of exchange rate variability in the firm's choice of whether to offer one or two varieties. We show that variability induces the firm to vertically segment markets (offer two varieties). This happens because variability in the exchange rate affects income dispersion and hence the firm's incentives to extract consumer surplus. To better extract surplus, the firm offers two price‐quality menus, a high‐quality variant geared for top‐end surplus extraction and a low‐quality variant to address market coverage concerns. Copyright © 2007 John Wiley & Sons, Ltd.
Validity of methyl mercury hair analysis: mercury monitoring in human scalp/nude mouse model
Authors: Zareba Grazyna , Cernichiari Elsa , Goldsmith Lowell A. , Clarkson Thomas W. 
Published: November 2007

AbstractObjective. The grafting of human scalp hair was used as a new application of this method to explore methyl mercury incorporation into human hair and to validate this model for mercury monitoring in hair.Methods. Human scalp grafts were transplanted to athymic BALB/c nude mice. The animals were exposed to methyl mercury either as a single dose i.p. or continuously for 4 months, using ALZET osmotic pumps. The mercury concentration in hair was determined using x‐ray fluorescence (XRF) spectrometry by segmental (2 mm) analysis of a single strand, and tissue concentrations were measured by cold vapor atomic absorption analysis.Results. Human scalp hair grown in nude mice showed long‐term persistence of human features including the expression of histocompatibility antigens (KAB 3, W 6/32, SF 1‐1.1.1) and normal hair morphometry. The disposition of methyl mercury in nude mice followed a one‐compartment model with a whole body elimination half‐life of 6.7 days (elimination constant, k = 0.1/day). Autoradiographic studies revealed that methyl mercury was rapidly incorporated into areas of the hair follicle undergoing active keratinization. Methyl mercury concentrations in human hair transplanted onto nude mice were two orders of magnitude higher than in blood and attained a mean hair: blood ratio of 217 : 1, similar to ratios reported only in human studies.Conclusions. This study demonstrated that human hair grown on nude mice can record the level of exposure to methyl mercury and can serve as a valuable research tool to study mercury incorporation into human hair. Copyright © 2007 John Wiley & Sons, Ltd.