bluuebunny/crossref_metadata_2025 huggingface dataset:
Estrogenic regulation of tissue factor and tissue factor pathway inhibitor in platelets
Authors: Jayachandran Muthuvel , Sanzo Antonio , Owen Whyte G. , Miller Virginia M.
Published: June 2005

Oral estrogen treatment increases thrombotic risk. Tissue factor (TF), tissue factor pathway inhibitor (TFPI), and platelet interaction with leukocytes are important determinants of thrombogenesis. Therefore, the present study was designed to define and compare platelet TF and TFPI mRNA and adhesion protein expression in platelets derived from animals treated with different types of oral estrogens. Ovariectomized pigs were treated with 17β-estradiol (2 mg/day), conjugated equine estrogen (CEE; 0.625 mg/day), or raloxifene (60 mg/day) for 4 wk. Compared with intact animals, ovariectomy and treatment differentially affected populations of leukocytes: neutrophils decreased whereas lymphocytes increased significantly 4 wk after ovariectomy and with 17β-estradiol and CEE treatments; eosinophils increased only with 17β-estradiol treatment. Content of TF protein increased in platelets from 17β-estradiol- and raloxifene-treated pigs, whereas TF mRNA was detected only in platelets from 17β-estradiol- and CEE treated pigs. TFPI mRNA increased in platelets after ovariectomy and estrogen treatment. Only a trace of TFPI protein was detected, but a higher-molecular-mass protein was observed in all treatment groups. Expression of CD40 and CD40 ligand increased with ovariectomy and decreased with 17β-estradiol and CEE treatments more than with raloxifene. The ratio of activated to basal P-selectin expression decreased with ovariectomy and increased with raloxifene treatments. These results suggest that estrogenic formulations may affect individual thrombotic risk by different mechanisms that regulate TF and platelet-leukocytic interactions. These studies provide the rationale for evaluation of interactions among platelets and TF and TFPI expression on thrombin generation during estrogen treatment in humans.
Anionic poly(amino acid)s dissolve F-actin and DNA bundles, enhance DNase activity, and reduce the viscosity of cystic fibrosis sputum
Authors: Tang Jay X. , Wen Qi , Bennett Andrew , Kim Brian , Sheils Catherine A. , Bucki Robert , Janmey Paul A.
Published: June 2005

Bundles of F-actin and DNA present in the sputum of cystic fibrosis (CF) patients but absent from normal airway fluid contribute to the altered viscoelastic properties of sputum that inhibit clearance of infected airway fluid and exacerbate the pathology of CF. Previous strategies to remove these filamentous aggregates have focused on DNase to enzymatically depolymerize DNA to constituent monomers and gelsolin to sever F-actin to small fragments. The high densities of negative surface charge on DNA and F-actin suggest that the bundles of these filaments, which alone exhibit a strong electrostatic repulsion, may be stabilized by multivalent cations such as histones, antimicrobial peptides, and other positively charged molecules prevalent in airway fluid. This study reports that bundles of DNA or F-actin formed after addition of histone H1 or lysozyme are efficiently dissolved by soluble multivalent anions such as polymeric aspartate or glutamate. Addition of poly-aspartate or poly-glutamate also disperses DNA and actin-containing bundles in CF sputum and lowers the elastic moduli of these samples to levels comparable to those obtained after treatment with DNase I or gelsolin. Addition of poly-aspartic acid also increased DNase activity when added to samples containing DNA bundles formed with histone H1. When added to CF sputum, poly-aspartic acid significantly reduced the growth of bacteria, suggesting activation of endogenous antibacterial factors. These findings suggest that soluble multivalent anions have potential alone or in combination with other mucolytic agents to selectively dissociate the large bundles of charged biopolymers that form in CF sputum.
Cyclic mechanical strain increases reactive oxygen species production in pulmonary epithelial cells
Authors: Chapman Kenneth E. , Sinclair Scott E. , Zhuang Daming , Hassid Aviv , Desai Leena P. , Waters Christopher M.
Published: June 2005

Overdistention of lung tissue during mechanical ventilation may be one of the factors that initiates ventilator-induced lung injury (VILI). We hypothesized that cyclic mechanical stretch (CMS) of the lung epithelium is involved in the early events of VILI through the production of reactive oxygen species (ROS). Cultures of an immortalized human airway epithelial cell line (16HBE), a human alveolar type II cell line (A549), and primary cultures of rat alveolar type II cells were cyclically stretched, and the production of superoxide (O2−) was measured by dihydroethidium fluorescence. CMS stimulated increased production of O2− after 2 h in each type of cell. 16HBE cells exhibited no significant stimulation of ROS before 2 h of CMS (20% strain, 30 cycles/min), and ROS production returned to control levels after 24 h. Oxidation of glutathione (GSH), a cellular antioxidant, increased with CMS as measured by a decrease in the ratio of the reduced GSH level to the oxidized GSH level. Strain levels of 10% did not increase O2− production in 16HBE cells, whereas 15, 20, and 30% significantly increased generation of O2−. Rotenone, a mitochondrial complex I inhibitor, partially abrogated the stretch-induced generation of O2− after 2 h CMS in 16HBE cells. NADPH oxidase activity was increased after 2 h of CMS, contributing to the production of O2−. Increased ROS production in lung epithelial cells in response to elevated stretch may contribute to the onset of VILI.
Wood smoke extract induces oxidative stress-mediated caspase-independent apoptosis in human lung endothelial cells: role of AIF and EndoG
Authors: Liu Po-Len , Chen Yuh-Lien , Chen Yung-Hsiang , Lin Shing-Jong , Kou Yu Ru
Published: June 2005

Although a link between toxic smoke and oxidant lung vascular injury has been indicated, the cellular mechanisms of smoke-induced injury to lung endothelial cells are unknown. We investigated oxidative stress and apoptosis induced by wood smoke extract (SE) in human pulmonary artery endothelial cells (HPAECs) and delineated their relationship. We found that SE increased intracellular reactive oxygen species (ROS), depleted intracellular glutathione, and upregulated Cu/Zn superoxide dismutase and heme oxygenase-1 (2 antioxidant enzymes), but it failed to alter the expression of catalase and glutathione peroxidase. In addition, SE promoted apoptosis as indicated by the external exposure of membrane phosphatidylserine, the loss of mitochondrial membrane potential, an increase in the level of Bax (a proapoptotic protein), and enhanced DNA fragmentation. This apoptosis was associated with mitochondrial-to-nuclear translocation of apoptosis-inducing factor (AIF) and endonuclease G (EndoG) (2 apoptogenic proteins) but was independent of caspase cascade activation. Whereas N-acetylcysteine (an antioxidant) effectively reversed the SE-induced increase in ROS and depletion of glutathione, it also suppressed SE-induced nuclear translocation of either AIF or EndoG and prevented the enhanced DNA fragmentation that would have resulted from this. We conclude that 1) although SE upregulates Cu/Zn superoxide dismutase and heme oxygenase-1, it nevertheless increases intracellular oxidative stress in HPAECs, and 2) SE promotes oxidative stress-mediated caspase-independent HPAEC apoptosis that involves mitochondrial-to-nuclear translocation of AIF and EndoG. Thus modulations of the expression of antioxidant enzymes and the caspase-independent apoptotic pathway are possible target choices for potential therapeutic regimes to treat smoke-induced lung injury.
Pulmonary vascular effects of nitric oxide-cGMP augmentation in a model of chronic pulmonary hypertension in fetal and neonatal sheep
Authors: Deruelle Philippe , Grover Theresa R. , Abman Steven H.
Published: June 2005

Persistent pulmonary hypertension of the newborn (PPHN) is partly due to impaired nitric oxide (NO)-cGMP signaling. BAY 41-2272 is a novel direct activator of soluble guanylate cyclase, but whether this drug may be an effective therapy for PPHN is unknown. We hypothesized that BAY 41-2272 would cause pulmonary vasodilation in a model of severe PPHN. To test this hypothesis, we compared the hemodynamic response of BAY 41-2272 to acetylcholine, an endothelium-dependent vasodilator, and sildenafil, a selective inhibitor of PDE5 in chronically instrumented fetal lambs at 1 and 5 days after partial ligation of the ductus arteriosus. After 9 days, we delivered the animals by cesarean section to measure their hemodynamic responses to inhaled NO (iNO), sildenafil, and BAY 41-2272 alone or combined with iNO. BAY 41-2272 caused marked pulmonary vasodilation, as characterized by a twofold increase in blood flow and a nearly 60% fall in PVR at day 1. Effectiveness of BAY 41-2272-induced pulmonary vasodilation increased during the development of pulmonary hypertension. Despite a similar effect at day 1, the pulmonary vasodilator response to BAY 41-2272 was greater than sildenafil at day 5. At birth, BAY 41-2272 dramatically reduced PVR and augmented the pulmonary vasodilation induced by iNO. We concluded that BAY 41-2272 causes potent pulmonary vasodilation in fetal and neonatal sheep with severe pulmonary hypertension. We speculate that BAY 41-2272 may provide a novel treatment for severe PPHN, especially in newborns with partial response to iNO therapy.
Cellular mechanisms of thromboxane A2-mediated contraction in pulmonary veins
Authors: Ding Xueqin , Murray Paul A.
Published: June 2005

Our objectives were to identify the relative contributions of [Ca2+]i and myofilament Ca2+ sensitivity in the pulmonary venous smooth muscle (PVSM) contractile response to the thromboxane A2 mimetic U-46619 and to assess the roles of PKC, tyrosine kinases (TK), and Rho-kinase (ROK) in that response. We tested the hypothesis that U-46619-induced contraction in PVSM is mediated by both increases in [Ca2+]i and myofilament Ca2+ sensitivity and that the PKC, TK, and ROK signaling pathways are involved. Isometric tension was measured in isolated endothelium-denuded (E−) canine pulmonary venous (PV) rings. In addition, [Ca2+]i and tension were simultaneously measured in fura-2-loaded E− PVSM strips. U-46619 (0.1 nM–1 μM) caused dose-dependent ( P < 0.001) contraction in PV rings. U-46619 contraction was attenuated by inhibitors of L-type voltage-operated Ca2+ channels (nifedipine, P < 0.001), inositol 1,4,5-trisphosphate-mediated Ca2+ release (2-aminoethoxydiphenylborate, P < 0.001), PKC (bisindolylmaleimide I, P < 0.001), TK (tyrphostin A-47, P = 0.014), and ROK (Y-27632, P = 0.008). In PV strips, U-46619 contraction was associated with increases in [Ca2+]i and myofilament Ca2+ sensitivity. Both Ca2+ influx and release mediated the early transient increase in [Ca2+]i, whereas the late sustained increase in [Ca2+]i only involved Ca2+ influx. Inhibition of both PKC and ROK ( P = 0.006 and P = 0.002, respectively), but not TK, attenuated the U-46619-induced increase in myofilament Ca2+ sensitivity. These results suggest that U-46619 contraction is mediated by Ca2+ influx, Ca2+ release, and increased myofilament Ca2+ sensitivity. The PKC, TK, and ROK signaling pathways are involved in U-46619 contraction.
Human endogenous antibiotic LL-37 stimulates airway epithelial cell proliferation and wound closure
Authors: Shaykhiev Renat , Beißwenger Christoph , Kändler Kerstin , Senske Judith , Püchner Annette , Damm Thomas , Behr Jürgen , Bals Robert
Published: June 2005

Antimicrobial peptides are endogenous antibiotics that directly inactivate microorganisms and in addition have a variety of receptor-mediated functions. LL-37/hCAP-18 is the only cathelicidin found in humans and is involved in angiogenesis and regulation of the innate immune system. The aim of the present study was to characterize the role of the peptide LL-37 in the regulation of wound closure of the airway epithelium in the cell line NCI-H292 and primary airway epithelial cells. LL-37 stimulated healing of mechanically induced wounds in monolayers of the cell line and in differentiated primary airway epithelium. This effect was detectable at concentrations of 5 μg/ml in NCI-H292 and 1 μg/ml in primary cells. The effect of LL-37 on wound healing was dependent on the presence of serum. LL-37 induced cell proliferation and migration of NCI-H292 cells. Inhibitor studies in the wound closure and proliferation assays indicated that the effects caused by LL-37 are mediated through epidermal growth factor receptor, a G protein-coupled receptor, and MAP/extracellular regulated kinase. In conclusion, LL-37 induces wound healing, proliferation, and migration of airway epithelial cells. The peptide is likely involved in the regulation of tissue homeostasis in the airways.
Chronic hypoxia elevates intracellular pH and activates Na+/H+exchange in pulmonary arterial smooth muscle cells
Authors: Rios Eon J. , Fallon Michele , Wang Jian , Shimoda Larissa A.
Published: June 2005

Chronic hypoxia (CH), caused by many lung diseases, results in pulmonary hypertension due, in part, to increased muscularity of small pulmonary vessels. Pulmonary arterial smooth muscle cell (PASMC) proliferation in response to growth factors requires increased intracellular pH (pHi) mediated by activation of Na+/H+exchange (NHE); however, the effect of CH on PASMC pHihomeostasis is unknown. Thus we measured basal pHiand NHE activity and expression in PASMCs isolated from mice exposed to normoxia or CH (3 wk/10% O2). pHiwas measured using the pH-sensitive fluorescent dye BCECF-AM. NHE activity was determined from Na+-dependent recovery from NH4-induced acidosis, and NHE expression was determined by RT-PCR and immunoblot. PASMCs from chronically hypoxic mice exhibited elevated basal pHiand increased NHE activity. NHE1 was the predominate isoform present in mouse PASMCs, and both gene and protein expression of NHE1 was increased following exposure to CH. Our findings indicate that exposure to CH caused increased pHi, NHE activity, and NHE1 expression, changes that may contribute to the development of pulmonary hypertension, in part, via pH-dependent induction of PASMC proliferation.
Impact of CFTR ΔF508 mutation on prostaglandin E2production and type IIA phospholipase A2expression by pulmonary epithelial cells
Authors: Medjane Samir , Raymond Benoit , Wu Yongzheng , Touqui Lhousseine
Published: June 2005

Cystic fibrosis (CF) is characterized by an exacerbated inflammatory pulmonary response with excessive production of inflammatory mediators. We investigated here the impact of cystic fibrosis transmembrane conductance regulator (CFTR) dysfunction on prostaglandin E2(PGE2) production and type IIA secreted phospholipase A2(sPLA2-IIA) expression. We show that both resting and LPS-stimulated human respiratory epithelial cell line bearing ΔF508 mutation on CFTR (CF cells) released more PGE2than control cell line. This was accompanied by enhanced expression and activity of cyclooxygenase-2 in CF cells. PGE2release was attenuated after experimentally induced retrafficking of the ΔF508-CFTR at the plasma membrane. sPLA2-IIA expression occurred at higher levels in CF cells than in control cells and was enhanced by LPS and PGE2. Suppression of PGE2synthesis by aspirin led to an inhibition of LPS-induced sPLA2-IIA expression. Higher activation of NF-κB was observed in CF cells compared with control cells and was enhanced by LPS. However, addition of PGE2or aspirin had no effect on NF-κB activation. LPS-induced sPLA2-IIA expression was reduced by an NF-κB inhibitor. We suggest that the lack of the CFTR in the plasma membrane results in a PGE2overproduction and an enhanced sPLA2-IIA expression. This expression is upregulated by NF-κB and amplified by PGE2via a unidentified signaling pathway.
Tree-Local Multicomponent Tree-Adjoining Grammars with Shared Nodes
Authors: Kallmeyer Laura
Published: June 2005

This article addresses the problem that the expressive power of tree-adjoining grammars (TAGs) is too limited to deal with certain syntactic phenomena, in particular, with scrambling in free-word-order languages. The TAG variants proposed so far in order to account for scrambling are not entirely satisfying. Therefore, the article introduces an alternative extension of TAG that is based on the notion of node sharing, so-called (restricted) tree-local multicomponent TAG with shared nodes (RSN-MCTAG). The analysis of some German scrambling data is sketched in order to show that this TAG extension can deal with scrambling. Then it is shown that for RSN-MCTAGs of a specific type, equivalent simple range concatenation grammars can be constructed. As a consequence, these RSN-MCTAGs are mildly context-sensitive and in particular polynomially parsable. These specific RSN-MCTAGs probably can deal not with all scrambling phenomena, but with an arbitrarily large subset.
Representing Discourse Coherence: A Corpus-Based Study
Authors: Wolf Florian , Gibson Edward
Published: June 2005

This article aims to present a set of discourse structure relations that are easy to code and to develop criteria for an appropriate data structure for representing these relations. Discourse structure here refers to informational relations that hold between sentences in a discourse. The set of discourse relations introduced here is based on Hobbs (1985).

We present a method for annotating discourse coherence structures that we used to manually annotate a database of 135 texts from the Wall Street Journal and the AP Newswire. Alltexts were independently annotated by two annotators. Kappa values of greater than 0.8 indicated good interannotator agreement.

We furthermore present evidence that trees are not a descriptively adequate data structure for representing discourse structure: In coherence structures of naturally occurring texts, we found many different kinds of crossed dependencies, as well as many nodes with multiple parents. The claims are supported by statistical results from our hand-annotated database of 135 texts.
A General Technique to Train Language Models on Language Models
Authors: Nederhof Mark-Jan
Published: June 2005

We show that under certain conditions, a language model can be trained on the basis of a second language model. The main instance of the technique trains a finite automaton on the basis of a probabilistic context-free grammar, such that the Kullback-Leibler distance between grammar and trained automaton is provably minimal. This is a substantial generalization of an existing algorithm to train an n-gram model on the basis of a probabilistic context-free grammar.
A Mathematical Model of Historical Semantics and the Grouping of Word Meanings into Concepts
Authors: Cooper Martin C.
Published: June 2005

A statistical analysis of polysemy in sixteen English and French dictionaries has revealed that, in each dictionary, the number of senses per word has a near-exponential distribution. A probabilistic model of historical semantics is presented which explains this distribution. This mathematical model also provides a means of estimating the average number of distinct concepts per word, which was found to be considerably less than the average number of senses listed per word. The grouping of word senses into concepts is based on whether they could inspire the same new senses (by metaphor, metonymy, etc.), that is, their potential future rather than their history.
Characterization of Castor Oil and Diphenyl Methane Diisocyanate-based Polyurethane-Polystyrene Interpenetrating Networks
Authors: Singh Paramjit , Kaushik Anupama , Gupta Pooja
Published: June 2005

Castor oil is an abundant natural polyol. It has been subjected to extensive investigations for polyurethane formation, suitable for a variety of applications. In this work, polyurethane prepolymers have been synthesized by bulk polycondensation of the moisture-free castor oil with diphenyl methane diisocyanate at room temperature. These prepolymers have been then cross-linked in situ with different quantities of styrene to prepare simultaneous interpenetrating polymer networks (IPNs). The composition of the polyurethane and polystyrene IPNs ranges from 10 to 50% by weight. The morphology, mechanical properties, chemical absorption, and swelling behavior of the IPNs prepared have been analyzed to evaluate the effect of styrene content in the IPNs. The tensile modulus improves with increasing quantity of styrene with a maximum at 50%. The absorption of these IPNs is maximum in pyridine and decreases with increasing quantity of styrene up to 40% and a sudden jump has been observed for 50% styrene content. For swelling study, the diffusivity coefficient increases with increasing PS content while sorption coefficient shows a decreasing trend.
Dynamic Interlaminar Stresses in Laminated Plates with Piezoelectric Actuators in Thermal Environments
Authors: Wang Xi , Xiao Jun
Published: June 2005

The response histories and distribution of dynamic interlaminar stresses in laminated plates with piezoelectric actuators in thermal environments, under free vibration are studied based on thermoelectrodynamic differential equations. The stacking sequence of the laminated plates may be arbitrary. The temperature field is considered as a linear function of coordinates in-plane of each layer and the electric field is considered as the transverse component Ez only. The dynamic mode of displacements is considered as a triangle series. The in-plane stresses are calculated by using geometric equations and generalized Hooke’s law. The interlaminar stresses are evaluated by integrating the 3-D equations of dynamic equilibrium, and utilizing the given boundary conditions and continuity conditions of stresses between layers. The numerical illustrations concern the response histories and the distribution of interlaminar stress in the laminated plates with fully covered or embedded piezoelectric actuators under different sets of thermal load and electric excitation. The theoretical analyses and results are of certain significance in practical engineering applications.
Mechanical Properties of Knitted Composites using Glass Ply Yarns
Authors: Dev V. R. Giri , Swarna A. , Madhusoothanan M.
Published: June 2005

In this paper, double layered rib knitted, glass fabric-reinforced epoxy laminates made of untwisted roving and twisted ply yarns are investigated for their tensile, flexural, and impact properties. The effect of stacking sequence [0/0 and 0/90] and the introduction of inlay fiber strands on the above-mentioned properties are also studied. Introduction of inlays leads to superior mechanical properties in the coursewise direction compared to that in the walewise direction. Impact property of the 0/90 stacking sequence was found to be superior compared to that of the 0/0 sequencing. Composites reinforced with twisted ply yarns result in slightly lower mechanical properties compared to the mechanical properties of laminates reinforced with untwisted roving strands.
Cure Characterization of Pultruded Soy-based Composites
Authors: Liang G. , Garg A. , Chandrashekhara K. , Flanigan V. , Kapila S.
Published: June 2005

Polymer matrix composites using renewable resources are currently of great interest. A novel soy-based resin system for pultrusion was synthesized at University of Missouri-Rolla (UMR). Due to relatively low reactivity of soy-based resin and short curing time of pultrusion, it is important to set up the process parameters properly in order to obtain a high quality pultruded product. In the present work, a combination of experimental and numerical methods is used to investigate the effect of pultrusion process variables on the cure of composites. A mathematical model has been developed and implemented in the commercial ABAQUS finite element package to predict the temperature and degree of cure of soy-based composites. The kinetic parameters of the soy-based epoxy resins are obtained from a differential scanning calorimeter (DSC). Glass fiber-reinforced composite samples are manufactured using a pultrusion machine. For experimental verification, an online monitoring system is used to measure the temperature profiles inside the die. The degrees of cure of pultruded soy-based composites are measured by DSC. The experimental findings are in good agreement with the finite element prediction. The results indicate that the novel soy-based epoxy resin system is suitable for application in the pultrusion process.
A Finite Element Investigation on the Effect of Cross-sectional Warping on Flexural Response of Laminated Composites and Sandwiches using Higher-order Shear Deformation Theory
Authors: Goswami Sanjib
Published: June 2005

An investigation on the effect of cross-sectional warping on the flexural response of laminates and sandwiches has been presented in this work. A simple C0finite element formulation of a higher-order shear deformation theory for thick and thin laminated composite and sandwich plates have been put forward. The assumed displacement model accounts for nonlinear variation of in-plane displacements and constant transverse displacement through the plate thickness. Moreover, this theory does not require any fictitious shear correction factors generally associated with the first-order shear deformation theory. For thick laminated plates, the bending response is highly affected by the cross-sectional warping. The so-called Mindlin's theory cannot capture this warping phenomenon due to linear variation of in-plane displacements. Only higherorder theories with higher-order terms in the in-plane displacement expression are required to compute displacements and stresses in the correct way. It has been shown that the free shear condition at the top and bottom bounding planes can be imposed in a simple way. The accuracy and validity of the present approach has been established through the numerical evaluation of deformation and stresses and their comparison with the available analytical/3D elasticity solutions and other published finite element results. The results from the present investigation compare fairly well with that of the other methods and finally some important conclusions have been made regarding the basic assumptions of CLT and Mindlin-type theories. It has been established that higher-order shear deformation theories and the modeling of cross-sectional warping are necessary for analyzing thick layered plates, specially soft-core sandwich plates.
Impact, Compression, Density, Void Content, and Weight Reduction Studies on Waste Silk Fabric/Epoxy Composites
Authors: Priya S. Padma , Rai S. K.
Published: June 2005

This paper describes the impact and compression properties of waste silk fabric/epoxy composites with reference to the effect of varying waste silk fabric content within them. Maximum strength in the properties determined is observed for the optimum fabric loading. Properties like density, void content, and weight reduction were also determined for these composites. There is a marked reduction in the void content of the composites, as the weight percentage of the silk increased. The total weight of the composites reduced to a small percentage with the increase in the fabric reinforcement in the composites.
Effects of Friction, Geometry, and Fixture Compliance on the Perceived Toughness from Three-and Four-Point Bend End-Notched Flexure Tests
Authors: Davidson Barry D. , Sun Xuekun
Published: June 2005

Linear and nonlinear finite element analyses are used to examine the effects of friction, test geometry, and fixture compliance on the perceived toughness as obtained from threeand four-point bend end-notched flexure tests. To this end, a newly developed ‘direct energy balance approach’ is used to obtain the ‘true’ energy release rate for any given specimen, test geometry, and coefficient of friction. Finite element analyses are also used in a simulated compliance calibration technique, which is combined with experimental results from fixture compliance tests to obtain a perceived toughness, i.e., the value that would be obtained by experiment. By varying the different parameters, the individual and combined effects of friction, test geometry, and fixture compliance on the ratio of the perceived to true toughness is obtained. The approach is applied to two graphite/epoxy materials for which toughnesses by the three(3ENF) and four-point bend end-notched flexure (4ENF) tests are obtained experimentally for a range of geometries. These experiments produced larger perceived mode II toughnesses, GIIc, by the 4ENF than the 3ENF test, and GIIc values from the 4ENF test were observed to decrease with increasing outer span length. The finite element simulations were shown to accurately recreate the perceived values of GIIc obtained from these tests. Moreover, the finite element simulations indicate that the true toughness values are essentially constant for a given material. These findings are used to make some general recommendations for choosing 3ENF and 4ENF specimen and test geometries, as well as to discuss the relative advantages and disadvantages of the 3ENF and 4ENF test methods.
New Remeshing Applications in Resin Transfer Molding
Authors: Soukane S. , Trochu F.
Published: June 2005

As resin transfer molding (RTM) is being increasingly used to manufacture composite parts, there is a strong interest to understand the basic physical phenomena that occur at each stage of the process. Modeling and simulation play an important role in the development and optimization of molds production and in devising appropriate resin injection strategies. In general, process simulation requires preprocessing to be carried out carefully to conduct successful, reliable, and reasonably fast calculations. However, it can be time consuming at the early stages of mold design to run several simulations with minor changes only in the geometrical model or in the mesh in order to optimize the mold or some given operating conditions. Unfortunately, in that case the entire mesh has usually to be regenerated. This paper presents applications of a remeshing algorithm to RTM flow simulation. It illustrates how remeshing techniques can be used to enhance the automatic meshing capability by including injection ports and channels along the mold boundaries or along the interior injection lines. Remeshing can also be used to smooth the resin front during mold filling. In the latter case, mesh refinement is based on the flow front without attempting to minimize computational error. By adapting the mesh anisotropy to the flow front during mold filling, the shape of the advancing flow front can be more closely approximated. The first part of this paper describes the remeshing algorithm and the associated anisotropic metric. Then, several examples of metrics are given to provide guidelines for application engineers and also to illustrate their practical implementation. After introducing the RTM process and recalling the basic equations that govern mold filling, local remeshing of injection ports and runners are presented, followed by the application that minimizes front smearing.
First-ply Failure Analysis of Laminated Composite Cylindrical Panels
Authors: Rattanawangcharoen N.
Published: June 2005

A first-ply failure (FPF) analysis of laminated composite cylindrical panels is presented in this paper. In the computation of stress and strain components, a 3D layerwise mixed stress-displacement finite element model is employed. The maximum stress, Tsai-Hill, Tsai-Wu, and Hoffman failure theories are used in the prediction of the FPF loads. This study illustrates that all four theories provide more or less the same FPF loads. The effects of the ply layup scheme, the fiber orientation angle, the panel thickness, the loading direction, and the location of the opening on the FPF loads of laminated cylindrical panels, are studied.
Investigation on the Vibration and Stability of Hybrid Composite Plates
Authors: Chen Chun-Sheng
Published: June 2005

In this study, the governing equations are derived for the buckling and vibration behaviors of hybrid composite plates having a general state of nonuniform initial stress based on the Reissner–Mindlin plate theory. The equations include the effects of transverse shear and rotary inertia. Using these derived governing equations, the natural frequencies and buckling loads of hybrid composite (Al/GFRP/Al) plates are investigated. The initial stress is taken to be a combination of pure bending stress and uniform normal stress in the example problems. The natural frequency and buckling load are sensitive to the thickness ratio of Al to GFRP and the state of initial stresses. The effects of various parameters on the natural frequencies and buckling loads are presented here.
Optimization of a Composite Rotor Blade using a Genetic Algorithm with Local Search
Authors: Lee Ya-Jung , Lin Ching-Chieh , Ji Jin-Chih , Chen Jong-Sheng
Published: June 2005

The material and ply angles of a fiber-reinforced plastic (FRP) rotor blade of a helicopter are optimized using a genetic algorithm (GA) with local search. The variation of the structural stiffness with material and ply angle is investigated. The aim of the optimization is to find an optimal stacking sequence that minimizes twist deformation. An optimum rotor blade is obtained using the ply angles as variables; failure, natural frequency, and minimum moment of inertia are used to constrain the optimization. The GA is employed as an optimization tool. A simplified local search is implemented in the final stage of optimization to reduce the searching time.
Freeze–Thaw Response of Glass–Polyester Composites at Different Loading Rates
Authors: Ray B. C.
Published: June 2005

The present literature suggests the need for investigating and characterizing the freeze–thaw response of polymer composites under different loading rates and also at ambient and sub-ambient temperatures. The present experiment has been carried out with three different weight fractions (i.e., 0.55, 0.6, and 0.65) of glass fiber-reinforced polyester composites. The short beam shear specimens are suddenly exposed to 80 C for 2 h and then a three-point bend test is conducted instantaneously at this temperature. Another batch of samples is allowed to thaw at ambient temperature for 1 h and tested on flexural mode at ambient temperature. The testing was carried out for a range of 0.5–500 mm/min crosshead speed. The shear strengths at cryogenic temperature and thawing temperature are compared with the room temperature-tested data of the shear value of laminates.
A description of physical therapists' knowledge in managing musculoskeletal conditions
Authors: Childs John D , Whitman Julie M , Sizer Phillip S , Pugia Maria L , Flynn Timothy W , Delitto Anthony
Published: June 2005

Background

Physical therapists increasingly provide direct access services to patients with musculoskeletal conditions, and growing evidence supports the cost-effectiveness of this mode of healthcare delivery. However, further evidence is needed to determine if physical therapists have the requisite knowledge necessary to manage musculoskeletal conditions. Therefore, the purpose of this study was to describe physical therapists' knowledge in managing musculoskeletal conditions.

Methods

This study utilized a cross-sectional design in which 174 physical therapist students from randomly selected educational programs and 182 experienced physical therapists completed a standardized examination assessing knowledge in managing musculoskeletal conditions. This same examination has been previously been used to assess knowledge in musculoskeletal medicine among medical students, physician interns and residents, and across a variety of physician specialties.

Results

Experienced physical therapists had higher levels of knowledge in managing musculoskeletal conditions than medical students, physician interns and residents, and all physician specialists except for orthopaedists. Physical therapist students enrolled in doctoral degree educational programs achieved significantly higher scores than their peers enrolled in master's degree programs. Furthermore, experienced physical therapists who were board-certified in orthopaedic or sports physical therapy achieved significantly higher scores and passing rates than their non board-certified colleagues.

Conclusion

The results of this study may have implications for health and public policy decisions regarding the suitability of utilizing physical therapists to provide direct access care for patients with musculoskeletal conditions.
A review of stress-relapse interactions in multiple sclerosis: important features and stress-mediating and -moderating variables
Authors: Brown R F , Tennant C C , Dunn S M , Pollard J D
Published: June 2005

Studies do not provide a consensus opinion of the relationship between stress and relapse in relapsing=remitting multiple sclerosis (RRMS). Few studies have defined the critical features of these stressful situations, or examined the role of stress-mediating and -moderating variables. Available evidence indicates that the relationship between life stress and relapse is complex, and is likely to depend on factors such as stressor chronicity, frequency, severity and type, and individual patient characteristics such as depression, health locus of control and coping strategy use. Little is known about how these factors, individually or in combination, are related to MS disease activity. Viral infections are also likely to precipitate relapse in MS, and significant life-stress may further enhance this relationship. The nature and strength of these interrelationships have strong clinical implications. MS patients are particularly vulnerable to a deteriorating cycle of stressful life events, illness episodes and disability. Timely multidisciplinary care interventions aimed at both minimizing psychological distress and physical symptoms may halt this downward reciprocal cycle. Little is known of the pathogenesis of these putative stress-induced changes in disease activity, and almost all stressor studies suffer from some biases or limitations.
Monthly brain magnetic resonance imaging scans in patients with clinically isolated syndrome
Authors: Pestalozza I F , Pozzilli C , Di Legge S , Piattella M C , Pantano P , Caramia F , Pasqualetti P , Lenzi G L
Published: June 2005

We investigated if monthly gadolinium (Gd)-enhanced magnetic resonance imaging (MRI) can assist the clinician in anticipating the diagnosis of multiple sclerosis (MS) in the very first few months following a clinically isolated syndrome (CIS). A consecutive series of CIS patients with ≥ 3 T2-weighted (T2W) hyperintense brain MRI lesions suggestive of MS were followed up for the first six consecutive months after enrollment with monthly triple-dose Gd-enhanced brain MRI scan. MRI conversion to MS was defined by the presence of either ≥ 1 new Gd-enhancing lesion or ≥ 1 new T2W lesions in the subsequent MRI scan. Sixty patients were included. Of them, 30 (50%) had at least one Gd-enhancing lesion on the baseline MRI scan. After three months, MRI conversion to MS was observed in 80% and 62% of patients based on the appearance of ≥ 1 new T2 lesion and ≥ 1 new Gd-enhancing lesions, respectively. The presence of ≥ 1 new T2W lesion was observed in 90% and 82% of patients who had, at baseline, a Gd-positive MRI scan and dissemination in space based on the new McDonald’s criteria, respectively. The rate of MRI conversion remained almost stable in the last two MRI scans. Our study suggests that the majority of CIS patients with an abnormal baseline scan showed an MRI conversion to MS after three months. The model of six months as the optimal interval for repeating MRI exam is not supported by the present data.
Motor determinants of gait in 100 ambulatory patients with multiple sclerosis
Authors: Thoumie P , Lamotte D , Cantalloube S , Faucher M , Amarenco G
Published: June 2005

A prospective analysis of gait and strength parameters was performed in 100 patients diagnosed with MS and pyramidal involvement admitted in a rehabilitation unit. The patients were divided into two groups based on their ability to walk in daily life (nonassisted or cane-assisted gait) and into four clinical subgroups depending on associated involvements such as sensory loss or cerebellar ataxia. Twenty healthy subjects were studied as a control group. Gait parameters were evaluated with a Locometre and muscle strength with an isokinetic dynamometer. The results showed that the average velocity and strength of the hamstring and quadriceps were strongly correlated and reduced in the MS group in comparison with the control, and in the cane-assisted group compared with the nonassisted group. Gait velocity tended to be more correlated to hamstring strength in the nonassisted group with a determination coefficient (r2) reaching a value of 0.44 in the sensory subgroup. These findings provide evidence that a correlation between strength reduction and gait impairment is obvious whatever the clinical form in patients with MS. This correlation is higher with hamstrings but may change depending on the disability level and the clinical form. This could be taken into account in the individual assessment of further rehabilitation programmes.
Reappraisal of Lhermitte’s sign in multiple sclerosis
Authors: Al-Araji Adnan H , Oger Joel
Published: June 2005

Lhermitte’s sign (LS) is strongly linked to multiple sclerosis (MS). Our aim is to reassess its frequency, natural history, various characteristics and neuroradiological correlation in a cohort of MS patients attending our specialized MS clinic and to propose a working definition. Consecutive patients with CDMS and normal controls were interviewed using a structured questionnaire. Cervical MRIs were reviewed when available. There were 300 MS patients and 100 normal controls. Forty-one per cent of the patients and none of the controls reported having LS during the course of their illness. In 53% of those who reported LS, it started in the first three years of the illness and began as an isolated symptom in 64% and was polysymptomatic in 36%. In all patients LS was a short-lasting sensation in all patient who experienced it and was mostly stereotyped in individual patients. Characteristics varied widely between patients. Forty-three patients had cervical MRIs; 17 out of 18 patients who reported LS had abnormalities, whereas only 13 out of the 25 with no LS had abnormalities. The results indicate that LS is highly prevalent in MS, is commonly stereotyped in individual patients, has a variable natural course and correlates significantly with cervical MRI abnormalities. A working definition is proposed.
The distribution of the magnetic resonance imaging response to glatiramer acetate in multiple sclerosis
Authors: Sormani M P , Bruzzi P , Comi G , Filippi M
Published: June 2005

We investigated the distribution of the magnetic resonance imaging (MRI)-measured response to glatiramer acetate (GA) treatment in multiple sclerosis (MS) using data from a clinical trial of relapsing=remitting (RR) MS. A fixed and a random effects model were used to quantify the between-patient heterogeneity in treatment response, expressed as new enhancing lesion percentage reduction. In 95% of the patients, lesion reduction due to treatment was estimated to range between -20% and -54%, indicating a rather homogeneous effect of GA on MRI-measured disease activity in RRMS.
Autoantigen-pulsed dendritic cells constitute a beneficial cytokine and growth factor network in ameliorating experimental allergic encephalomyelitis
Authors: Liu Xuan , Ciumas Carolina , Huang Yu-Min , Steffensen Knut R , Lian Hong , Link Hans , Xiao Bao-Guo
Published: June 2005

Injection of myelin basic protein (MBP)-pulsed dendritic cells (DC) into healthy rats, as we reported before and observed in this study, did not induce clinical experimental allergic encephalomyelitis (EAE), but effectively protected the rats from subsequent EAE induction. The mechanisms by which MBP-pulsed DC mediate immune protection are not completely understood. In the present study, we mainly explored the dynamic change of cytokine and growth factor mRNA expression in spinal cords after subcutaneous injection of MBP-pulsed and unpulsed DC. The expression of interleukin (IL)-1, interferon-g and tumour necrosis factor-a as well as programmed death ligand (PDL)-1, PDL-2, signal transducer and activator of transcription (STAT)4, STAT6, matrix metalloproteinase (MMP)-9 and tissue inhibitor of metalloproteinases (TIMP)-2 was increased on day 0 postimmunization (p.i.). The increase of IL-12 expression was observed on day 7 p.i., while the increase of IL-10 expression mainly occurred on day 14 p.i. Except downregulation of insulin-like growth factor-1, the expression of brain-derived neurotrophic factor, ciliary neurotrophic factor, fibroblast growth factor (FGF)-2 and platelet-derived growth factor (PDGF)-B/C as well as nerve growth factor receptor (NGF-R), FGF receptor, PDGF-R-a and b was elevated on day 0 p.i., while the increase of TIMP and NGF was observed on days 0 and 7 p.i. There were no significant differences on MMP-2, spinal cord-derived growth factor and PDGF-A mRNA expression. In line with the suppression of EAE induced by MBP-pulsed DC, the dynamic change of cytokines and growth factors in spinal cords should constitute a beneficial microenvironment against EAE.
Emotional responses of children and adolescents to parents with multiple sclerosis
Authors: Yahav Rivka , Vosburgh Janine , Miller Ariel
Published: June 2005

The effect of a chronic illness of one parent on children is determined by a complicated interaction of various emotional components. Our focus was on the children’s and adolescent’s emotional reactions and feelings towards their multiple sclerosis (MS)-affected parents, including: degree of responsibility, obligation and concern, yielding behaviour and active protection, fear and anxiety related to the state of illness, their sense of burden in connection with household tasks and errands, and anger. Fifty-six children, ages 10=18, each having a parent with MS, were examined. The results were compared to a control group of 156 age-matched children with healthy parents. Feelings were examined by means of a questionnaire previously constructed by us. We found that children of parents with MS felt more responsibility and obligation than children of healthy parents. They also exhibited more yielding behaviour, more fear and anxiety related to states of illness, a greater sense of burden and a greater degree of anger. We consider the interaction between the sex of the parent and the sex of the child in connection with these feelings and discuss the implications of the ‘parental child’ role of these children.
The mechanism of action of methylprednisolone in the treatment of multiple sclerosis
Authors: Sloka J S , Stefanelli M
Published: June 2005

Methylprednisolone plays an important role in the current treatment of multiple sclerosis (MS), particularly in the acute phase of relapse. It acts in various ways to decrease the inflammatory cycle including: dampening the inflammatory cytokine cascade, inhibiting the activation of T cells, decreasing the extravasation of immune cells into the central nervous system, facilitating the apoptosis of activated immune cells, and indirectly decreasing the cytotoxic effects of nitric oxide and tumor necrosis factor alpha. This paper reviews the most recent observations on these mechanisms both to understand the disease mechanism and its treatment. As more becomes known about these mechanisms, it may become possible to design treatment regimes that are more specific towards both the individual and the disease state.