bluuebunny/crossref_metadata_2025_split huggingface dataset:
Elastic and inelastic drift performance optimization for reinforced concrete buildings under earthquake loads
Authors: Chan Chun‐Man , Zou Xiao‐Kang 
Published: June 2004

AbstractThis paper presents an effective optimization technique for the elastic and inelastic drift performance design of reinforced concrete buildings under response spectrum loading and pushover loading. Attempts have been made to develop an automatic optimal elastic and inelastic drift design of concrete framework structures. The entire optimization procedure can be divided into elastic design optimization and inelastic design optimization. Using the principle of virtual work, the elastic drift response generated by the response spectrum loading and the inelastic drift response produced by the non‐linear pushover loading can be explicitly expressed in terms of element sizing design variables. The optimization methodology for the solution of the explicit design problem of buildings is fundamentally based on the Optimality Criteria approach. One ten‐story, two‐bay building frame example is presented to illustrate the effectiveness and practicality of the proposed optimal design method. While rapid convergence in a few design cycles is found in the elastic optimization process, relatively slow but steady and smooth convergence of the optimal performance‐based design is found in the inelastic optimization process. Copyright © 2004 John Wiley & Sons, Ltd.
Comparing the adequacy of alternative ground motion intensity measures for the estimation of structural responses
Authors: Giovenale Paolo , Cornell C. Allin , Esteva Luis 
Published: June 2004

AbstractPractical methods for the probability‐based seismic assessment of structures make use of estimates of demands produced by earthquakes of different intensities. The uncertainties associated with these estimates are highly dependent on the variable adopted as the intensity measure (IM, e.g., PGA, spectral acceleration, etc.). This generates the need to compare the efficiency of an originally adopted IMwith that of a new candidate. This implies comparing the dispersion of the demand measure (DM, e.g., maximum interstorey drift ratio, ductility demand, etc.) conditional to each of the two IMs. In order to obtain the demand estimates in a conventional way, a full set of dynamic response analyses should be performed for each IM under scrutiny, i.e., multiple records scaled at several fixed values of each IM.The procedure developed here serves to accelerate this comparison avoiding the effort required to evaluate the dynamic responses of the structure for all the ground motion time histories considered every time that a new IM is adopted. For this purpose, use is made of available results of analyses performed for a different (i.e., the original) IM. Two methods are proposed: the direct method involves performing a regression of the results obtained from the original analyses, taking the candidate IM as the independent variable. The indirect method involves rebuilding the probability density function of the DM given a defined value of the candidate IM by means of the total probability theorem, using the results of the original analyses and certain data relating the two IMs.The proposed methods have been tested by application to several SDOF systems with different periods and different cyclic‐response backbone curves. The conditions affecting their approximation are explored, and some criteria to improve them are identified. The procedure can also be used to determine the optimum value of a parameter to be used in a parameter‐based IM. Copyright © 2004 John Wiley & Sons, Ltd.
ZnT‐1 expression in astroglial cells protects against zinc toxicity and slows the accumulation of intracellular zinc
Authors: Nolte Christiane , Gore Ariel , Sekler Israel , Kresse Wolfgang , Hershfinkel Michal , Hoffmann Anja , Kettenmann Helmut , Moran Arie 
Published: June 2004

AbstractZinc ions are emerging as an important factor in the etiology of neurodegenerative disorders and in brain damage resulting from ischemia or seizure activity. High intracellular levels of zinc are toxic not only to neurons but also to astrocytes, the major population of glial cells in the brain. In the present study, the role of ZnT‐1 in reducing zinc‐dependent cell damage in astrocytes was assessed. Zinc‐dependent cell damage was apparent within 2 h of exposure to zinc, and occurred within a narrow range of ∼200 μM. Pretreatment with sublethal concentrations of zinc rendered astrocytes less sensitive to toxic zinc levels, indicating that preconditioning protects astrocytes from zinc toxicity. Fluorescence cell imaging revealed a steep reduction in intracellular zinc accumulation for the zinc‐pretreated cells mediated by L‐type calcium channels. Heterologous expression of ZnT‐1 had similar effects; intracellular zinc accumulation was slowed down and the sensitivity of astrocytes to toxic zinc levels was reduced, indicating that this is specifically mediated by ZnT‐1 expression. Immunohistochemical analysis demonstrated endogenous ZnT‐1 expression in cultured astroglia, microglia, and oligodendrocytes. Pretreatment with zinc induced a 4‐fold increase in the expression of the putative zinc transporter ZnT‐1 in astroglia as shown by immunoblot analysis. The elevated ZnT‐1 expression following zinc priming or after heterologous expression of ZnT‐1 may explain the reduced zinc accumulation and the subsequent reduction in sensitivity toward toxic zinc levels. Induction of ZnT‐1 may play a protective role when mild episodes of stroke or seizures are followed by a massive brain insult. © 2004 Wiley‐Liss, Inc.
Gangliosides activate microglia via protein kinase C and NADPH oxidase
Authors: Min Kyoung‐Jin , Pyo Han‐Kyung , Yang Myung‐Soon , Ji Kyung‐Ae , Jou Ilo , Joe Eun‐Hye 
Published: June 2004

AbstractMicroglia, the major immune effector cells in the central nervous system, are activated when the brain suffers injury. A number of studies indicate that gangliosides activate microglia. However, the signaling mechanisms involved in microglial activation are not yet to be elucidated. Our results show that gangliosides induce the expression of interleukin (IL)‐1β, tumor necrosis factor‐α (TNF‐α), and inducible nitric oxide synthase (iNOS) in rat brain microglia and BV2 murine microglia via protein kinase C (PKC) and NADPH oxidase. Expression of IL‐1β, TNF‐α, and iNOS in ganglioside‐treated cells was significantly reduced in the presence of inhibitors of PKC (GF109203X, Gö6976, Ro31‐8220, and rottlerin) and NADPH oxidase (diphenyleneiodonium chloride [DPI]). In response to gangliosides, PKC‐α, βII, and δ and NADPH oxidase p67phox translocated from the cytosol to the membrane. ROS generation was also activated within 5 min of ganglioside treatment. Ganglioside‐induced ROS generation was blocked by PKC inhibitors. Furthermore, ganglioside‐induced activation of NF‐κB, an essential transcription factor that mediates the expression of IL‐1β, TNF‐α, and iNOS, was reduced in the presence of GF109203X and DPI. Our results collectively suggest that gangliosides activate microglia via PKC and NADPH oxidase, which regulate activation of NF‐κB. © 2004 Wiley‐Liss, Inc.
Dehydroepiandrosterone regulates astroglia reaction to denervation of olfactory glomeruli
Authors: Hoyk Zsófia , Párducz Árpád , Garcia‐Segura Luis Miguel 
Published: June 2004

AbstractEffects of dehydroepiandrosterone (DHEA) on glial reactions of the peripherally denervated olfactory bulb were studied in adult male rats. Denervation was achieved by destroying the olfactory mucosa with ZnSO4 (0.17 M) irrigation of the nasal cavities. In one series of experiments, chronic DHEA treatment was applied (daily injections for 7 days, i.p., 10 mg/kg b.w. and 25 mg/kg b.w.); in the other series of experiments, animals received a single injection of DHEA (i.p., 10 mg/kg b.w., 25 mg/kg b.w. and 50 mg/kg b.w.) 2 h following ZnSO4 treatment. To determine whether DHEA conversion to estradiol was involved in the mechanism of DHEA action on glia, a third series of experiments was carried out in which the aromatase inhibitor fadrozole (4.16 mg/ml) was administered using subcutaneously implanted osmotic minipumps. Rats were killed on day 7 after chemical denervation, and the reaction of glial cells was monitored within the olfactory bulb, using GFAP and vimentin immunohistochemistry. Qualitative changes in GFAP expression were analyzed by Western blot. Chronic DHEA treatment with both doses (10 mg/kg b.w. and 25 mg/kg b.w.) and acute DHEA treatment with the highest dose applied (50 mg/kg b.w.), inhibited the increase in GFAP expression induced by the denervation of the olfactory bulb. Furthermore, GFAP and vimentin immunostaining in the glomerular layer of the olfactory bulb were diminished in the denervated and DHEA treated groups. However, when DHEA treatment was combined with fadrozole administration, such a decrease in GFAP expression could not be detected in the chemically denervated olfactory bulb. These findings indicate that DHEA, depending on the dose applied and the mode of administration, attenuates glial reaction to denervation and may regulate glial plasticity in the olfactory glomeruli. These effects are likely to be mediated at least in part by the conversion of DHEA to estradiol. © 2004 Wiley‐Liss, Inc.
Evidence that the branched‐chain α‐keto acids accumulating in maple syrup urine disease induce morphological alterations and death in cultured astrocytes from rat cerebral cortex
Authors: Funchal Cláudia , Gottfried Carmem , Vieira De Almeida Lúcia Maria , Wajner Moacir , Pessoa‐Pureur Regina 
Published: June 2004

AbstractSevere neurological symptoms, cerebral edema, and atrophy are common features of the inherited metabolic disorder maple syrup urine disease (MSUD). However, the pathomechanisms involved in the neuropathology of this disease are not well established. In this study, we investigated the effects of the branched‐chain keto acids (BCKA) α‐ketoisocaproic (KIC), α‐ketoisovaleric (KIV), and α‐keto–β–methylvaleric (KMV), which accumulate in MSUD, on astrocyte morphology and cytoskeleton reorganization. Cultured astrocytes from cerebral cortex of neonatal rats were exposed to various concentrations of the BCKA and cell morphology was studied. We observed that these cells changed their usual polygonal morphology when exposed to BCKA, leading to the appearance of fusiform or process‐bearing cells. Furthermore, longer exposures to the BCKA elicited cell death at all concentrations studied, attaining massive death at the highest concentrations. Immunocytochemistry with anti‐actin or anti‐GFAP antibodies revealed that the BCKA induced reorganization of actin and GFAP cytoskeleton. In addition, astrocytes treated with lysophosphatidic acid, an upstream activator of the RhoA GTPase pathway, totally prevented the morphological alterations and cytoskeletal reorganization induced by KIV, indicating that this effect could be mediated by the RhoA signaling pathway. Furthermore, the effects of BCKA on astrocyte morphology were prevented by creatine. In addition, creatine kinase activity was inhibited by KIC and KIV; this inhibition was prevented by creatine, indicating that these keto acids compromise brain energy metabolism. Considering that astroglial cells are critical to brain development and functioning, it is conceivable that alterations of the actin network by BCKA may have important implications in astrocytic function and possibly in the pathogenesis of the neurological dysfunction and brain damage of MSUD patients. © 2004 Wiley‐Liss, Inc.
Money for health: the equivalent variation of cardiovascular diseases
Authors: Groot Wim , van den Brink Henriëtte Maassen , Plug Erik 
Published: June 2004

AbstractThis paper introduces a new method to calculate the extent to which individuals are willing to trade money for improvements in their health status. An individual welfare function of income (WFI) is applied to calculate the equivalent income variation of health impairments. We believe that this approach avoids various drawbacks of alternative willingness‐to‐pay methods. The WFI is used to calculate the equivalent variation of cardiovascular diseases. It is found that for a 25 year old male the equivalent variation of a heart disease ranges from €114 000 to €380 000 depending on the welfare level. This is about €10 000–€30 000 for an additional life year. The equivalent variation declines with age and is about the same for men and women. The estimates further vary by discount rate chosen. The estimates of the equivalent variation are generally higher than the money spent on most heart‐related medical interventions per QALY. The cost‐benefit analysis shows that for most interventions the value of the health benefits exceeds the costs. Heart transplants seem to be too costly and only beneficial if patients are young. Copyright © 2004 John Wiley & Sons, Ltd.
On the interpretation of a concentration index of inequality
Authors: Koolman Xander , van Doorslaer Eddy 
Published: June 2004

AbstractThis paper aims to add a more intuitive understanding to the concept of a concentration index for measuring relative inequality with an application of health‐related measures by income. A new redistribution interpretation and an existing redistribution interpretation of the Gini are presented and applied to the concentration index. Both indicate the share of the total amount of any variable that needs redistributing in a particular way from rich to poor (or vice versa) to achieve a concentration index equal to zero. The characteristics of these redistribution schemes are compared. The paper also draws attention to the relationship between a concentration index, a correlation coefficient with relative income rank and a coefficient of variation of the variable of interest. These relationships are illustrated using data on inequality in dental care utilisation in European countries taken from the European Community Household Panel survey. Copyright © 2004 John Wiley & Sons, Ltd.
Economic valuation of informal care: the contingent valuation method applied to informal caregiving
Authors: van denBerg Bernard , Brouwer Werner , Exel Job van , Koopmanschap Marc 
Published: June 2004

AbstractThis paper reports the results of the application of the contingent valuation method (CVM) to determine a monetary value of informal care. We discuss the current practice in valuing informal care and a theoretical model of the costs and benefits related to the provision of informal care. In addition, we developed a survey in which informal caregivers' willingness to accept (WTA) to provide an additional hour of informal care was elicited. This method is better than normally recommended valuation methods able to capture the heterogeneity and dynamics of informal care.Data were obtained from postal surveys. A total of 153 informal caregivers and 149 care recipients with rheumatoid arthritis returned a completed survey. Informal caregivers reported a mean WTA to provide a hypothetical additional hour of informal care of 9.52 Euro (n=124). Many hypotheses derived from the theoretical model and the literature were supported by the data.CVM is a promising alternative for existing methods like the opportunity cost method and the proxy good method to determine a monetary value of informal care that can be incorporated in the numerator of any economic evaluation. Copyright © 2004 John Wiley & Sons, Ltd.
Valuation of the risk of SARS in Taiwan
Authors: Liu Jin‐Tan , Hammitt James K. , Wang Jung‐Der , Tsou Meng‐Wen 
Published: June 2004

AbstractTwo surveys conducted in Taiwan during the spring 2003 severe acute respiratory syndrome (SARS) epidemic reveal a high degree of concern about the threat posed by SARS to Taiwan and its residents, although respondents believe they are knowledgeable about the risk of SARS and that it is susceptible to individual control. Willingness to pay (WTP) to reduce the risk of infection and death from SARS is elicited using contingent valuation methods. Estimated WTP is high, implying values per statistical life of US$3 to 12 million. While consistent with estimates for high‐income countries, these values are substantially larger than previous estimates for Taiwan and may be attributable to the high degree of concern about SARS at the time the data were collected. Copyright © 2004 John Wiley & Sons, Ltd.
Comparing costing results in across country economic evaluations: the use of technology specific purchasing power parities
Authors: Wordsworth Sarah , Ludbrook Anne 
Published: June 2004

AbstractThe number of economic evaluations conducted on a multinational basis is increasing. Therefore, techniques are required to compare the results of such studies in a meaningful manner. This paper explores different approaches to comparing across country cost data applied to a European study of dialysis therapy for end‐stage renal disease. A price and volume index is created at the level of the individual health care technology and compared to an exchange rate conversion and published purchasing power parities (PPPs). Both exchange rate and PPP conversions when published rates are used fail to accurately reflect the true resource use of the applied health care example. These differences can be related to specific issues of input mix and price variation. Alternatively, the use of technology specific PPPs provided a more robust approach for international comparisons and also have the potential for use in multi‐centre economic evaluations within the same country. Copyright © 2004 John Wiley & Sons, Ltd.
Assessing generalisability by location in trial‐based cost‐effectiveness analysis: the use of multilevel models
Authors: Manca Andrea , Rice Nigel , Sculpher Mark J. , Briggs Andrew H. 
Published: June 2004

AbstractAn Erratum has been published for this article in Health Economics 14(5) 2005, 486.Cost‐effectiveness analysis (CEA) in health care is increasingly conducted alongside multicentre and multinational randomised controlled clinical trials (RCTs). The increased use of stochastic CEA is designed to account for between‐patient sampling variability in cost‐effectiveness data assuming that observations are independently distributed. However, between‐location variability in cost‐effectiveness may result if there is a hierarchical structure in the data; that is, if there is correlation in costs and outcomes between patients recruited in particular locations. This may be expected in multi‐location trials given that centres and countries often differ in factors such as clinical practice, patient case‐mix and the unit costs of delivering health care. A failure to acknowledge this feature may lead to misleading conclusions in a trial‐based economic study. Multilevel modelling (MLM) is an analytical framework that can be used to handle hierarchical cost‐effectiveness data. Using data from a recently conducted economic analysis, this paper shows how multilevel modelling can be used to obtain (a) more appropriate estimates of the population average incremental cost‐effectiveness and associated standard errors compared to standard stochastic CEA; and (b) location‐specific estimates of incremental cost‐effectiveness which can be used to explore appropriately the variability between centres/countries of the cost‐effectiveness results. Copyright © 2004 John Wiley & Sons, Ltd.
Risk aversion and uncertainty in cost‐effectiveness analysis: the expected‐utility, moment‐generating function approach
Authors: Elbasha Elamin H. 
Published: June 2004

AbstractThe availability of patient‐level data from clinical trials has spurred a lot of interest in developing methods for quantifying and presenting uncertainty in cost–effectiveness analysis (CEA). Although the majority has focused on developing methods for using sample data to estimate a confidence interval for an incremental cost–effectiveness ratio (ICER), a small strand of the literature has emphasized the importance of incorporating risk preferences and the trade‐off between the mean and the variance of returns to investment in health and medicine (mean‐variance analysis).This paper shows how the exponential utility–moment‐generating function approach is a natural extension to this branch of the literature for modelling choices from healthcare interventions with uncertain costs and effects. The paper assumes an exponential utility function, which implies constant absolute risk aversion, and is based on the fact that the expected value of this function results in a convenient expression that depends only on the moment‐generating function of the random variables. The mean‐variance approach is shown to be a special case of this more general framework.The paper characterizes the solution to the resource allocation problem using standard optimization techniques and derives the summary measure researchers need to estimate for each programme, when the assumption of risk neutrality does not hold, and compares it to the standard incremental cost–effectiveness ratio. The importance of choosing the correct distribution of costs and effects and the issues related to estimation of the parameters of the distribution are also discussed. An empirical example to illustrate the methods and concepts is provided. Copyright © 2004 John Wiley & Sons, Ltd.
Using multilevel models for assessing the variability of multinational resource use and cost data
Authors: Grieve Richard , Nixon Richard , Thompson Simon G. , Normand Charles 
Published: June 2004

AbstractMultinational economic evaluations often calculate a single measure of cost‐effectiveness using cost data pooled across several countries. To assess the validity of pooling international cost data the reasons for cost variation across countries need to be assessed. Previously, ordinary least‐squares (OLS) regression models have been used to identify factors associated with variability in resource use and total costs. However, multilevel models (MLMs), which accommodate the hierarchical structure of the data, may be more appropriate. This paper compares these different techniques using a multinational dataset comprising case‐mix, resource use and cost data on 1300 stroke admissions from 13 centres in 11 European countries. OLS and MLMs were used to estimate the effect of patient and centre‐level covariates on the total length of hospital stay (LOS) and total cost. MLMs with normal and gamma distributions for the data within centres were compared. The results from the OLS model showed that both patient and centre‐level covariates were associated with LOS and total cost. The estimates from the MLMs showed that none of the centre‐level characteristics were associated with LOS, and the level of spending on health was the centre‐level variable most highly associated with total cost. We conclude that using OLS models for assessing international variation can lead to incorrect inferences, and that MLMs are more appropriate for assessing why resource use and costs vary across centres. Copyright © 2004 John Wiley & Sons, Ltd.