bluuebunny/crossref_metadata_2025_split huggingface dataset:
Predicting in vivo failure of pseudoelastic NiTi devices under low cycle, high amplitude fatigue
Authors: Young Jeremy M. , Van Vliet Krystyn J. 
Published: August 2004

AbstractDue to the large reversible strains achievable through the stress‐induced austenite–martensite phase transformation in NiTi alloys, NiTi has replaced stainless steel in the majority of large‐strain biomedical applications such as root canal enlargement. However, the pseudoelasticity of NiTi is currently overshadowed by the short fatigue life of NiTi wires used in this low cycle (200–2000 rpm), high amplitude (εa > 2.5%) application, resulting in in vivo fracture or premature retirement of otherwise reusable NiTi‐based wire devices. In this study, the failure of pseudoelastic 55.8 wt % Ni‐Ti wire is investigated experimentally, as a function of experimental parameters that include the clinically relevant regime. The effects of radius of curvature, angle of curvature, wire diameter, strain amplitude, cyclic frequency, volume under strain, and specific heat of the surrounding environmental fluid are considered systematically. These data indicate that the lifetime or cycles to failure Nf of a rotating NiTi wire can be predicted via a modified Coffin‐Manson relation that is a strong function of both strain amplitude and volume under strain, and a weaker function of frequency and fluid specific heat. The resulting quantitative relation can be used to predict useful device lifetime under clinically relevant conditions and thereby reduce incidences of in vivo failure. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 72B: 17–26, 2005
The parameterization and validation of generalized born models using the pairwise descreening approximation
Authors: Michel Julien , Taylor Richard D. , Essex Jonathan W. 
Published: August 2004

AbstractGeneralized Born Surface Area (GBSA) models for water using the Pairwise Descreening Approximation (PDA) have been parameterized by two different methods. The first method, similar to that used in previously reported parameterizations, optimizes all parameters against the experimental free energies of hydration of organic molecules. The second method optimizes the PDA parameters to compensate only for systematic errors of the PDA. The best models are compared to Poisson–Boltzmann calculations and applied to the computation of potentials of mean force (PMFs) for the association of various molecules. PMFs present a more rigorous test of the ability of a solvation model to correctly reproduce the screening of intermolecular interactions by the solvent, than its accuracy at predicting free energies of hydration of small molecules. Models derived with the first method are sometimes shown to fail to compute accurate potentials of mean force because of large errors in the computation of Born radii, while no such difficulties are observed with the second method. Furthermore, accurate computation of the Born radii appears to be more important than good agreement with experimental free energies of solvation. We discuss the source of errors in the potentials of mean force and suggest means to reduce them. Our findings suggest that Generalized Born models that use the Pairwise Descreening Approximation and that are derived solely by unconstrained optimization of parameters against free energies of hydration should be applied to the modeling of intermolecular interactions with caution. © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 1760–1770, 2004
Evidence of reciprocal regulation between the high extracellular calcium and RANKL signal transduction pathways in RAW cell derived osteoclasts
Authors: Xu Jiake , Wang Cathy , Han Renzhi , Pavlos Nathan , Phan Tony , Steer James H. , Bakker Anthony J. , Joyce David A. , Zheng Ming H. 
Published: August 2004

AbstractDuring bone resorption, osteoclasts are exposed to high Ca2+ concentrations (up to 40 mM). The role of high extracellular Ca2+ in receptor activator of NF‐κB ligand (RANKL)‐mediated osteoclast survival and their functional interrelationship is unclear. In this study, we show that RANKL enhances osteoclast tolerance to high extracellular Ca2+ by protecting the cell from cell death in a dose dependent manner. We have provided evidence that RANKL does this by attenuating high extracellular Ca2+‐induced Ca2+ elevations. Moreover, we have found that high extracellular Ca2+‐induced cell death was partially inhibited by a caspase‐3 inhibitor, suggesting caspase‐3‐mediated apoptosis is involved. Conversely, using reporter gene assays and Western blot analysis, we have demonstrated that high extracellular Ca2+ desensitizes the RANKL‐induced activation of NF‐κB and c‐Jun N‐terminal kinase (JNK), and inhibits constitutive and RANKL‐stimulated ERK phosphorylation, indicating a negative feed‐back mechanism via specific RANKL signaling pathways. Taken together, this study provides evidence for a reciprocal regulation between high extracellular Ca2+ and RANKL signaling in RAW cell derived osteoclasts. Our data imply a cross talk mechanism of extracellular Ca2+ on osteoclast survival through the regulation of RANKL. © 2004 Wiley‐Liss, Inc.
Molecular and cellular regulation of glucose transporter (GLUT) proteins in cancer
Authors: Macheda Maria L. , Rogers Suzanne , Best James D. 
Published: August 2004

AbstractMalignant cells are known to have accelerated metabolism, high glucose requirements, and increased glucose uptake. Transport of glucose across the plasma membrane of mammalian cells is the first rate‐limiting step for glucose metabolism and is mediated by facilitative glucose transporter (GLUT) proteins. Increased glucose transport in malignant cells has been associated with increased and deregulated expression of glucose transporter proteins, with overexpression of GLUT1 and/or GLUT3 a characteristic feature. Oncogenic transformation of cultured mammalian cells causes a rapid increase of glucose transport and GLUT1 expression via interaction with GLUT1 promoter enhancer elements. In human studies, high levels of GLUT1 expression in tumors have been associated with poor survival. Studies indicate that glucose transport in breast cancer is not fully explained by GLUT1 or GLUT3 expression, suggesting involvement of another glucose transporter. Recently, a novel glucose transporter protein, GLUT12, has been found in breast and prostate cancers. In human breast and prostate tumors and cultured cells, GLUT12 is located intracellularly and at the cell surface. Trafficking of GLUT12 to the plasma membrane could therefore contribute to glucose uptake. Several factors have been implicated in the regulation of glucose transporter expression in breast cancer. Hypoxia can increase GLUT1 levels and glucose uptake. Estradiol and epidermal growth factor, both of which can play a role in breast cancer cell growth, increase glucose consumption. Estradiol and epidermal growth factor also increase GLUT12 protein levels in cultured breast cancer cells. Targeting GLUT12 could provide novel methods for detection and treatment of breast and prostate cancer. © 2004 Wiley‐Liss, Inc.
Oncostatin M stimulates proliferation and functions of mouse fetal liver cells in three‐dimensional cultures
Authors: Ehashi Tomo , Miyoshi Hirotoshi , Ohshima Norio 
Published: August 2004

AbstractIn order to develop a tissue engineered bioartificial liver (BAL), long‐term three‐dimensional (3‐D) culture of fetal liver cells (FLCs) utilizing porous polymer as a scaffold was performed for up to 1 month. The effects of the basal medium and supplementation with oncostatin M (OSM) on the proliferation and differentiation of mouse FLCs were examined in both 3‐D culture and conventional monolayer dish culture. Compared with monolayer culture, cell numbers and hepatic function of FLCs were better maintained by 3‐D culture. When two kinds of basal media were tested in this study, Williams' medium E (WE) was superior to minimum essential medium alpha (αMEM) in expressing hepatic function of FLCs in both 3‐D and monolayer cultures, although higher cell densities were obtained with αMEM. OSM potently stimulated both cell growth and metabolic activity, especially in 3‐D culture. When WE supplemented with OSM was used for 3‐D culture, albumin secretion by FLCs increased dramatically after day 5, and a high level of secretion was maintained until the end of culture. During a period of over 1 month, no decrease of albumin secretion was observed. In conclusion, this 3‐D culture method was expected to be one of the realistic attempts to develop a tissue engineered BAL. © 2004 Wiley‐Liss, Inc.
LiCl inhibits the establishment of left‐right asymmetry in larvae of the direct‐developing echinoid Peronella japonica
Authors: Kitazawa Chisato , Takai Kaori Kajihara , Nakajima Yoko , Fujisawa Hirosuke , Amemiya Shonan 
Published: August 2004

AbstractThe effect of LiCl on the establishment of left‐right (LR) asymmetry in larvae of the direct‐developing echinoid Peronella japonica was investigated with special attention to the location of the amniotic opening and ciliary band pattern. The larvae of echinoids are LR symmetric, but shortly before metamorphosis the larval LR symmetry is lost as a result of the formation of an amniotic cavity (vestibule), part of the adult rudiment, on the left side of the body. P. japonica has been considered to be the only exception among the echinoids, because the amniotic cavity forms at the midline of the larval body. In the present study we discovered the following two different LR asymmetric traits in larvae of P. japonica: the opening of the amniotic cavity initially forms at the midline of the larval body but shifts to the left dorsal side, and a looped ciliary band that initially forms with LR symmetry becomes LR asymmetric as a result of the formation of a bulge on left dorsal side. The establishment of LR asymmetry in both the location of the amniotic opening and the change in the shape of the ciliary band was influenced by exposing embryos to LiCl. Quantitative analysis of the shift in amniotic opening showed that exposure of embryos to LiCl causes repression of leftward shifting of the amniotic opening in earlier stage larvae, and leftward or rightward shifting in later stage larvae. These findings suggest that LiCl is an effective means of impairing the establishment of LR asymmetry in sea urchin embryos. J. Exp. Zool. 301A:707–717, 2004. © 2004 Wiley‐Liss, Inc.
Scaling effects on metabolism of a teleost
Authors: Tripathi G. , Verma Priyanka 
Published: August 2004

AbstractScaling effects on citrate synthase (CS), glucose‐6‐phosphate dehydrogenase (G6‐PDH), RNA. RNA/DNA ratio and protein contents of brain, liver and skeletal muscle were studied in a teleost, Clarias batrachus. The activity of white skeletal muscle CS decreased significantly as a function of increasing body mass of the fish. It shows that the fulfilment of energy demand in white skeletal muscle is not dependent on aerobic metabolism. The activity of liver G6‐PDH decreased with the increasing body mass showing reduction in NADPH generation for lipogenic activity. However, increase in G6‐PDH activity showed enhancement in reductive synthesis in skeletal muscle of the larger‐sized individuals. A positive scaling of RNA, RNA/DNA ratio and protein contents reflects changes in macromolecular turnover for ATP‐supplying enzymes and proteins. J. Exp. Zool. 301A:718–726, 2004. © 2004 Wiley‐Liss, Inc.
Species‐specific effects on hemolymph glucose control by serotonin, dopamine, and L‐enkephalin and their inhibitors in Squilla mantis and Astacus leptodactylus (crustacea)
Authors: Lorenzon Simonetta , Brezovec Sara , Ferrero Enrico A. 
Published: August 2004

AbstractHemolymph glucose level is controlled by crustacean Hyperglycemic Hormone (cHH) released from the eyestalk neuroendocrine centers under conditions of both physiological and environmental stress. Biogenic amines and enkephalin have been found to mediate the release of several neurohormones from crustacean neuroendocrine tissue. We investigated the effect of serotonin, dopamine, and Leucine‐enkephalin in vivo—injected into the stomatopod Squilla mantis and the decapod Astacus leptodactylus—whether increasing or depressing glycemia. Serotonin had a marked effect in elevating glucose level compared with initial values in both species. 5–HT1–like receptors are more involved in mediating serotonin action as co‐injected cyproheptadine was a more effective antagonist than ketanserin (5–HT2–like receptor inhibitor). Dopamine injection in intact animals produced a decrease below initial levels of hemolymph glucose. This effect was significantly antagonized by domperidone. No significant effect of both amines occurred in eyestalkless animals. L‐enkephalin shows a differential effect: in S. mantis it induced hypoglycemia while in A. leptodactylus it caused an increase of glucose level. Co‐injected antagonist naloxone affected the direction of the response. Serotonin appears to provide a major control on glucose mobilization, whereas dopamine and L‐enkephalin act as modulators whose plasticity in use or action varies among species. J. Exp. Zool. 301A:727–736, 2004. © 2004 Wiley‐Liss, Inc.
Yolk partitioning in embryos of the lizard, Calotes versicolor: Maximize body size or save energy for later use?
Authors: Radder Rajkumar S. , Shanbhag Bhagyashri A. , Saidapur Srinivas K. 
Published: August 2004

AbstractThe hatchlings of Calotes versicolor and other congeners retain residual yolk for immediate post‐hatching needs. Excision of 8% yolk (≌residual yolk) from the eggs resulted in smaller hatchlings when compared to those emerging from sham operated eggs. However, hatchlings in both groups retained the same amount of residual yolk. The findings suggest that residual yolk in hatchlings of C. versicolor is an important part of the energy budget set aside by developing embryos and that the advantages of large hatchling size are counter balanced by selection for residual yolk. J. Exp. Zool. 301A:783–785, 2004. © 2004 Wiley‐Liss, Inc.
A field study of group diversity, workgroup context, and performance
Authors: Jehn Karen A. , Bezrukova Katerina 
Published: August 2004

AbstractWe explore how the context of an organizational workgroup affects the relationship between group diversity and various performance outcomes. In particular, we theorize and empirically examine the moderating effects of three categories of workgroup context variables: cultures (people‐ and competition‐oriented), strategies (stability‐, growth‐ and customer‐oriented), and human resource practices (diversity‐ and training‐oriented). We perform analyses on 1528 workgroups from a Fortune 500 information‐processing firm. The results showed, for example, that members of groups diverse in functional background were paid higher composite bonuses when their workgroup context emphasized people‐oriented cultures and lower levels of bonuses in contexts with a focus on stability‐oriented strategies. In addition, members of groups diverse in level of education were awarded higher amounts of bonuses in workgroup environments that emphasized customer‐ and growth‐oriented strategies. However, members of such groups had lower levels of composite bonuses in environments that focused on training‐ and diversity‐oriented human resource practices. We discuss future research directions regarding diversity, workgroup context, and performance outcomes and outline some implications for managers and group leaders. Copyright © 2004 John Wiley & Sons, Ltd.
Diversity in social context: a multi‐attribute, multilevel analysis of team diversity and sales performance
Authors: Jackson Susan E. , Joshi Aparna 
Published: August 2004

AbstractPrior research on demographic diversity in work teams has yielded mixed results, with the effects of team diversity ranging from positive to neutral to negative. This article shows that an improved understanding of the relationship between team diversity and team performance can be reached by considering the combined effects of team diversity and demographic social context. We hypothesized that three aspects of the social context would moderate the effects of demographic diversity on performance: the combination of diversity dimensions within a team, the demographic characteristics of the team manager, and the demography of the work unit. In a study of 365 sales teams distributed across 42 sales districts in a large U.S. company, we found support for the general proposition that the demographic social context moderates relationships between team diversity and team performance. We discuss the practical implications of these results as well as the research implications for future studies of team diversity. Copyright © 2004 John Wiley & Sons, Ltd.
A field study of group diversity, participation in diversity education programs, and performance
Authors: Ely Robin J. 
Published: August 2004

AbstractThis study examined the impact of four dimensions of diversity—tenure, age, sex, and race—on performance in 486 retail bank branches and assessed whether employee participation in the firm's diversity education programs influenced these relationships. Data came from archives of the demographic composition of branches, an employee attitude–satisfaction poll, and branch performance assessed as part of the bank's bonus incentive plan. Race and sex diversity were unrelated to performance. The direct effects of tenure and age diversity were largely negative, but were moderated by quality of team processes, suggesting that cooperation and teamwork may suppress potentially task‐enhancing differences associated with these aspects of diversity. Diversity education programs had minimal impact on performance. The results of this study suggest that there is a complex relationship between age and tenure diversity and performance and that, even in firms with characteristics that should be conducive to performance benefits from diversity, other conditions must be in place to foster such effects. Copyright © 2004 John Wiley & Sons, Ltd.
Topographical properties of polymer films deposited in capillaries for electrophoretic separations of large organic molecules
Authors: Guryča Vilém , Pacáková Veřa , Tlust'áková Marie , Štulík Karel , Michálek Jiří 
Published: August 2004

AbstractTopography and thickness of hydrophilic polymer coatings of fused‐silica capillaries for capillary electrophoresis (CE) were investigated using atomic force microscopy (AFM), scanning electron microscopy (SEM), and profilometry. Three hydrogels, poly(2‐hydroxyethyl methacrylate) [poly(HEMA)], poly(diethylene glycol monomethacrylate) [poly(DEGMA)], and poly(triethylene glycol monomethacrylate) [poly‐(TEGMA)], were deposited using two procedures, either by simple physical sorption of the polymers, or by derivatization of the capillary wall surface with glycidyl methacrylate (EPMA) followed by polymerization of the appropriate monomers. The performance of the modified capillaries was tested under CE conditions (decrease in the electroosmotic flow, EOF dependence on pH, separation of milk and standard proteins). It has been found that the most important property of the polymer coating is its thickness, whereas its topography and the degree of its hydrophobicity are less significant. Film deposition by physical adsorption is preferable to polymerization on the derivatized surface.
Retention modelling in liquid chromatographic separation of simvastatin and six impurities using a microemulsion as eluent
Authors: Malenovic Andjelija , Ivanovic Darko , Medenica Mirjana , Jancic Biljana , Markovic Slavko 
Published: August 2004

AbstractA novel and unique approach was used for retention modelling in the separation of simvastatin and six impurities by liquid chromatographic using a microemulsion as mobile phase. A microemulsion is a modification of a micellar system where a lipophilic organic solvent is dissolved in the micelles; for that reason, microemulsions are usually treated as solvent‐modified micellar solutions. When microemulsions are used as eluents in HPLC separations, solutes partition between the charged oil droplets and the aqueous buffer phase. The complexity of the composition of the microemulsion permits extensive manipulations to be made during method development in order to achieve acceptable resolution of such a complex mixture of substances. In order to avoid a laborious “trial and error” procedure, a 23 full factorial design was applied for choosing an optimal microemulsion composition to obtain good separation in a reasonable run time. Organic solvent, sodium dodecyl sulphate, and n‐butanol content were varied within defined experimental domain. Optimal conditions for the separation of simvastatin and its six impurities were obtained using an X TerraTM 50×4.6 mm, 3.5 μm particle size column at 30°C. The mobile phase consisted of 0.9% w/w of diisopropyl ether, 2.2% w/w of sodium dodecylsulphate (SDS), 7.0% w/w of co‐surfactant such as n‐butanol, and 89.9% w/w of aqueous 25 mM disodium phosphate pH 7.0.
Characterization of sulfated β‐cyclodextrins and determination of enantiomeric purity of (1R,2S)‐ephedrine by capillary zone electrophoresis
Authors: Amini Ahmad , Rundlöf Torgny , Grön Rydberg May‐Britt , Arvidsson Torbjörn 
Published: August 2004

AbstractMatrix‐assisted laser‐desorption ionization time‐of‐flight (MALDI–TOF) mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy were employed to characterize two different sulfated β‐cyclodextrins (HS‐β‐CD). It was found that the HS‐β‐CDs have broad heterogeneity in terms of sulfation degree. The average sulfate contents were in the range of 6 to 8 per CD molecule. Furthermore the sugar moieties of both HS‐β‐CDs were sulfated either at position 6 or at positions 2 and 6, but not at position 3. Enantiomeric separation by capillary zone electrophoresis (CZE) using the HS‐β‐CDs as chiral selectors showed that these CDs exhibited similar chiral selectivity and resolution of the ephedrine enantiomers. One of the CDs was employed for the enantiomeric purity evaluation of (1R,2S)‐ephedrine (or (–)‐ephedrine) by capillary zone electrophoresis. Quantification was done by comparison between the corrected peak areas of the minor enantiomer and (–)‐ephedrine.
Structural Aspects of Poly(thiodiethylene terephthalate) Investigated by X‐Ray Powder Diffraction
Authors: Fichera Anna Maria , Finelli Lara , Gazzano Massimo , Lotti Nadia , Malta Viscardo , Munari Andrea 
Published: August 2004

AbstractSummary:The full‐profile refinement of X‐ray diffraction patterns was used to investigate two poly(thiodiethylene terephthalate) (PSDET) samples with different thermal history in order to thoroughly analyze their polymorphic aspects. In each sample, a crystalline (αorβ) and a microcrystalline (α′ orβ′) phase were identified together with an amorphous component. The crystal structures of all the ordered phases were determined. The data indicated an appreciable difference between the two crystalline forms, while the microcrystalline were rather similar. The results reported in this paper agree with the hypothesis that the polymorphic and morphological aspects of PSDET have to be correlated with the order degree and reorganization of crystallites and microcrystallites.Projection along theaaxis andcaxis ofα‐phase chain arrangement.magnified imageProjection along theaaxis andcaxis ofα‐phase chain arrangement.