bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence for species differences in the pattern of androgen receptor distribution in relation to species differences in an androgen‐dependent behavior
Authors: Shaw Brian K. , Kennedy Grace G. 
Published: October 2002

AbstractChickens (Gallus gallus domesticus) and Japanese quail (Coturnix japonica), two closely related gallinaceous bird species, exhibit a form of vocalization—crowing—which differs between the species in two components: its temporal acoustic pattern and its accompanying postural motor pattern. Previous work utilizing the quail‐chick chimera technique demonstrated that the species‐specific characteristics of the two crow components are determined by distinct brain structures: the midbrain confers the acoustic pattern, and the caudal hindbrain confers the postural pattern. Crowing is induced by androgens, acting directly on androgen receptors. As a strategy for identifying candidate neurons in the midbrain and caudal hindbrain that could be involved in crow production, we performed immunocytochemistry for androgen receptors in these brain regions in both species. We also investigated midbrain‐to‐hindbrain vocal‐motor projections. In the midbrain, both species showed prominent androgen receptor immunoreactivity in the nucleus intercollicularis, as had been reported in previous studies. In the caudal hindbrain, we discovered characteristic species differences in the pattern of androgen receptor distribution. Chickens, but not quail, showed strong immunoreactivity in the tracheosyringeal division of the hypoglossal nucleus, whereas quail, but not chickens, possessed strong immunoreactivity in a region of the ventrolateral medulla. Some of these differences in hindbrain androgen receptor distribution may be related to the species differences in the postural component of crowing behavior. The results of the present study imply that the spatial distribution of receptor proteins can vary even between closely related species. Such variation in receptor distribution could underlie the evolution of species differences in behavior. © 2002 Wiley Periodicals, Inc. J Neurobiol 52: 203–220, 2002
Presynaptic adenosine A1 receptors regulate retinohypothalamic neurotransmission in the hamster suprachiasmatic nucleus
Authors: Hallworth Richard , Cato Matthew , Colbert Costa , Rea Michael A. 
Published: October 2002

AbstractAdenosine has been implicated as a modulator of retinohypothalamic neurotransmission in the suprachiasmatic nucleus (SCN), the seat of the light‐entrainable circadian clock in mammals. Intracellular recordings were made from SCN neurons in slices of hamster hypothalamus using the in situ whole‐cell patch clamp method. A monosynaptic, glutamatergic, excitatory postsynaptic current (EPSC) was evoked by stimulation of the optic nerve. The EPSC was blocked by bath application of the adenosine A1 receptor agonist cyclohexyladenosine (CHA) in a dose‐dependent manner with a half‐maximal concentration of 1.7 μM. The block of EPSC amplitude by CHA was antagonized by concurrent application of the adenosine A1 receptor antagonist 8‐cyclopentyl‐1,3‐dipropylxanthine (DPCPX). The adenosine A2A receptor agonist CGS21680 was ineffective in attenuating the EPSC at concentrations up to 50 μM. Trains of four consecutive stimuli at 25 ms intervals usually depressed the EPSC amplitude. However, after application of CHA, consecutive responses displayed facilitation of EPSC amplitude. The induction of facilitation by CHA suggested a presynaptic mechanism of action. After application of CHA, the frequency of spontaneous EPSCs declined substantially, while their amplitude distribution was unchanged or slightly reduced, again suggesting a mainly presynaptic site of action for CHA. Application of glutamate by brief pressure ejection evoked a long‐lasting inward current that was unaffected by CHA at concentrations sufficient to reduce the evoked EPSC amplitude substantially (1 to 5 μM), suggesting that postsynaptic glutamate receptor‐gated currents were unaffected by the drug. Taken together, these observations indicate that CHA inhibits optic nerve‐evoked EPSCs in SCN neurons by a predominantly presynaptic mechanism. © 2002 Wiley Periodicals, Inc. J Neurobiol 52: 230–240, 2002
On the formulation of closest‐point projection algorithms in elastoplasticity—part I: The variational structure
Authors: Armero F. , Pérez‐Foguet A. 
Published: October 2002

AbstractWe present in this paper the characterization of the variational structure behind the discrete equations defining the closest‐point projection approximation in elastoplasticity. Rate‐independent and viscoplastic formulations are considered in the infinitesimal and the finite deformation range, the later in the context of isotropic finite‐strain multiplicative plasticity. Primal variational principles in terms of the stresses and stress‐like hardening variables are presented first, followed by the formulation of dual principles incorporating explicitly the plastic multiplier. Augmented Lagrangian extensions are also presented allowing a complete regularization of the problem in the constrained rate‐independent limit. The variational structure identified in this paper leads to the proper framework for the development of new improved numerical algorithms for the integration of the local constitutive equations of plasticity as it is undertaken in Part II of this work. Copyright © 2001 John Wiley & Sons, Ltd.
Three‐dimensional time‐harmonic Green's functions for a triclinic full‐space using a symbolic computation system
Authors: Dravinski Marijan , Niu Yuqing 
Published: October 2002

AbstractTime‐harmonic Green's functions for a triclinic anisotropic full‐space are evaluated through the use of a symbolic computation system.This procedure allows evaluation of the Green's functions for the most general anisotropic materials. The proposed computational algorithms are programmed in a MATLAB environment by incorporating symbolic calculations performed using Maple Computer Algebra System. Extensive testing of the numerical results has been performed for both displacement and stress fields. The tests demonstrate the accuracy of the proposed algorithm in evaluating the Green's functions. Copyright © 2001 John Wiley & Sons, Ltd.
Comparison of method of lines and finite difference solutions of 2‐D Navier–Stokes equations for transient laminar pipe flow
Authors: Selçuk Nevin , Tarhan Tanıl , Tanrıkulu Songül 
Published: October 2002

AbstractPerformances of method of lines (MOL) and finite difference method (FDM) were tested from the viewpoints of solution accuracy and central processing unit (CPU) time by applying them to the solution of time‐dependent 2‐D Navier–Stokes equations for transient laminar flow without/with sudden expansion and comparing their results with steady‐state numerical predictions and measurements previously reported in the literature. Predictions of both methods were obtained on the same computer by using the same order of spatial discretization and the same uniform grid distribution. Axial velocity and pressure distribution in pipe flow and steady‐state reattachment lengths in sudden expansion flow on uniform grid distribution predicted by both methods were found to be in excellent agreement. Transient solutions of both methods for pipe flow problem show favourable comparison and are in accordance with expected trends. However, non‐physical oscillations were produced by both methods in the transient solution of sudden expansion pipe flow. MOL was demonstrated to yield non‐oscillatory solutions for recirculating flows when intelligent higher‐order discretization scheme is utilized for convective terms. MOL was found to be superior to FDM with respect to CPU and set‐up times and its flexibility for incorporation of other conservation equations. Copyright © 2001 John Wiley & Sons, Ltd.
Development of shear locking‐free shell elements using an enhanced assumed strain formulation
Authors: César de Sá José M. A. , Natal Jorge Renato M. , Fontes Valente Robertt A. , Almeida Areias Pedro M. 
Published: October 2002

AbstractThe degenerated approach for shell elements of Ahmad and co‐workers is revisited in this paper. To avoid transverse shear locking effects in four‐node bilinear elements, an alternative formulation based on the enhanced assumed strain (EAS) method of Simo and Rifai is proposed directed towards the transverse shear terms of the strain field. In the first part of the work the analysis of the null transverse shear strain subspace for the degenerated element and also for the selective reduced integration (SRI) and assumed natural strain (ANS) formulations is carried out. Locking effects are then justified by the inability of the null transverse shear strain subspace, implicitly defined by a given finite element, to properly reproduce the required displacement patterns. Illustrating the proposed approach, a remarkably simple single‐element test is described where ANS formulation fails to converge to the correct results, being characterized by the same performance as the degenerated shell element. The adequate enhancement of the null transverse shear strain subspace is provided by the EAS method, enforcing Kirchhoff hypothesis for low thickness values and leading to a framework for the development of shear‐locking‐free shell elements. Numerical linear elastic tests show improved results obtained with the proposed formulation. Copyright © 2001 John Wiley & Sons, Ltd.
Meshfree analysis and design sensitivity analysis for shell structures
Authors: Kim Nam Ho , Choi Kyung Kook , Chen Jiun‐Shyan , Botkin Mark E. 
Published: October 2002

AbstractA unified design sensitivity analysis method for a meshfree shell structure with respect to size, shape, and configuration design variables is presented in this paper. A shear deformable shell formulation is characterized by a CAD connection, thickness degeneration, meshfree discretization, and nodal integration. Because of a strong connection to the CAD tool, the design variable is selected from the CAD parameters, and a consistent design velocity field is then computed by perturbing the surface geometric matrix. The material derivative concept is utilized in order to obtain a design sensitivity equation in the parametric domain. Numerical examples show the accuracy and efficiency of the proposed design sensitivity analysis method compared to the analytical solution and the finite difference solution. Copyright © 2002 John Wiley & Sons, Ltd.
A contact formulation based on localized Lagrange multipliers: formulation and application to two‐dimensional problems
Authors: Rebel G. , Park K. C. , Felippa C. A. 
Published: October 2002

AbstractThe non‐penetration condition in contact problems is traditionally based on the classical Lagrange multiplier method. This method makes extensive use of modelling details of the contacting bodies for contact enforcement as the contact surface meshes are in general non‐matching. To deal with this problem we introduce a novel element in the Lagrange multiplier approach of contact modelling, namely, a contact frame placed in between contacting bodies. It acts as a medium through which contact forces are transferred without violating equilibrium in the contact domain for discrete contact models. Only nodal information of the contacting bodies is required which makes the proposed contact enforcement generic. The contact frame has its own independent freedoms, which allows the formulation to pass contact patch tests by design. Copyright © 2002 John Wiley & Sons, Ltd.
Numerical modelling of shear bands by element bands
Authors: Wang X. , Chan D. , Morgenstern N. 
Published: October 2002

AbstractIt is presently a concern and challenge to numerically model shear band localization. Many numerical methods have been developed to take into account the strain and displacement discontinuities across a shear band. In this paper, a contact band element method is proposed to model the shear band with a finite thickness under large shear deformation. The shear band elements, alternatively called contact band elements, are continuously updated based on their current configurations to prevent the large distortions of conventional finite elements and maintain realistic shear band configurations. The contact band element method, with a technique for the special shear band element, consists of the schemes to keep the shear band elements in good shapes, handle the band overlapping, kinking and separation problems. A few examples have shown that the contact band element method is a very efficient way to model the shear bands under large shear deformation. Copyright © 2002 John Wiley & Sons, Ltd.
A 3D contact smoothing method using Gregory patches
Authors: Puso Michael Anthony , Laursen Tod A. 
Published: October 2002

AbstractIn this work, a method is developed for smoothing three‐dimensional contact surfaces. The method can be applied to both regular and irregular meshes. The algorithm employs Gregory patches to interpolate finite element nodes and provide tangent plane continuity between adjacent patches. The resulting surface interpolation is used to calculate gaps and contact forces, in a variationally consistent way, such that contact forces due to normal and frictional contact vary smoothly as slave nodes transition from one patch to the next. This eliminates the ‘chatter’ which typically occurs in a standard contact algorithm when a slave node is situated near a master facet edge. The elimination of this chatter provides a significant improvement in convergence behaviour, which is illustrated by a number of numerical examples. Furthermore, smoothed surfaces also provide a more accurate representation of the actual surface, such that resulting stresses and forces can be more accurately computed with coarse meshes in many problems. This fact is also demonstrated by the numerical examples. Published in 2002 by John Wiley & Sons, Ltd.
Adaptive hierarchical enrichment for delamination fracture using a decohesive zone model
Authors: Crisfield M. A. , Alfano G. 
Published: October 2002

AbstractThe paper describes a method for modelling delamination in fibre‐reinforced composite structures with the aid of a decohesive zone model and interface elements. Unless a fine mesh is provided, the resulting load/deflection responses are very non‐smooth and the iterative non‐linear solution procedure may fail. To overcome this problem, the elements around the softening process zone are enriched with hierarchical polynomial functions. The enriched zones change as the analysis proceeds and the cracks propagate. This procedure is implemented using a technique which continually modifies the boundary conditions. Copyright © 2002 John Wiley & Sons, Ltd.
Allelic imbalance analysis of chromosome 16q shows that grade I and grade III invasive ductal breast cancers follow different genetic pathways
Authors: Roylance Rebecca , Gorman Patricia , Hanby Andrew , Tomlinson Ian 
Published: October 2002

AbstractIt remains controversial as to whether low‐ and high‐grade invasive ductal breast cancers are related by progression through grade, or generally follow distinct genetic pathways. It has previously been shown by comparative genomic hybridization (CGH) that the latter is more likely to be correct, based on the high frequency of chromosome 16q deletion in grade I cancers, but not in grade III. This study used microsatellite markers on 16q to confirm the differences between grade I and grade III tumours and to exclude the possibility that grade III tumours generally arise from grade I tumours through a process involving regain of 16q. The concordance between the CGH and microsatellite data is good but imperfect, probably reflecting the different sensitivities and specificities of the two techniques and the varying mechanisms of allele loss in each tumour type. Copyright © 2002 John Wiley & Sons, Ltd.
VHL mutations and their correlation with tumour cell proliferation, microvessel density, and patient prognosis in clear cell renal cell carcinoma
Authors: Schraml Peter , Struckmann Kirsten , Hatz Florian , Sonnet Stefan , Kully Charlotte , Gasser Thomas , Sauter Guido , Mihatsch Michael J. , Moch Holger 
Published: October 2002

AbstractMutations of the von Hippel‐Lindau (VHL) gene are considered critical for the initiation of clear cell renal cell carcinoma. The VHL protein is involved in regulation of the cell cycle and neo‐vascularization. In this study, the association of VHL mutations with tumour cell proliferation, angiogenesis, and clinical outcome was analysed in 113 clear cell renal cell carcinomas. The degree of angiogenesis and tumour cell proliferation was immunohistochemically determined by counting microvessels (microvessel density, anti‐CD34 antibody) and cells with proliferating activity (Ki‐67 labelling index, MIB‐1 antibody). Forty‐eight different VHL sequence alterations were found in 38 of 113 patients (34%) by direct sequencing. Nineteen VHL mutations were frameshifts and nonsense mutations, predicted to change the open reading frame of VHL. These ‘loss‐of‐function’ mutations correlated with worse prognosis in univariate analysis (p=0.02). Tumour grade, stage, microvessel density, and tumour cell proliferation were not associated with VHL alterations. These findings may indicate that ‘loss‐of‐function’ VHL mutations are involved in the progression of a clear cell renal cell carcinoma subset, whereas regulation of angiogenesis and proliferation of renal carcinoma in vivo is apparently not directly influenced by VHL alterations. Copyright © 2001 John Wiley & Sons, Ltd.
Expression of Bcl‐x, Bcl‐2, Bax, and Bak in endarterectomy and atherectomy specimens
Authors: Saxena A. , McMeekin J. D. , Thomson D. J. 
Published: October 2002

AbstractThe regulation of apoptosis in atherosclerosis is not completely defined. The aim of this study was to determine the expression of Bcl‐2, Bcl‐x, Bax, and Bak in relation to apoptosis in advanced atherosclerotic lesions. In atherectomy (15), endarterectomy (10), and control non‐atherosclerotic segments of renal (2) and of coronary and carotid (5) arteries, the extent of apoptosis was determined using TdT dUTP nick end labelling (TUNEL) and nuclear morphology (karyorrhexis/pyknosis) and expression of apoptosis regulators by immunohistochemistry and western blot analysis on paraffin‐embedded material. In all specimens, the atherosclerotic involvement was advanced: grade V (n=18) and grade VI (n=7). The apoptotic index was high (mean 30%) in advanced lesions compared with controls (<2%) and smooth muscle cells (SMCs) were the predominant cell type undergoing apoptosis. In all TUNEL‐positive apoptotic cells, Bax and Bak were present, while Bcl‐x was absent. Bcl‐2 was absent in a majority of these cells, but occasional TUNEL‐positive cells expressed Bcl‐2. In non‐apoptotic cells, Bcl‐x was present and western blot detected only the long isoform, Bcl‐xL, from the plaques. In conclusion, increased Bax and Bak coupled with lack/paucity of Bcl‐2 and Bcl‐xL are associated with SMC apoptosis in advanced lesions. Bcl‐xL in non‐apoptotic cells appears to contribute to prolonged cell survival. Copyright © 2002 John Wiley & Sons, Ltd.
Macrophages expressing the scavenger receptor CD163: a link between immune alterations of the gut and synovial inflammation in spondyloarthropathy
Authors: Baeten Dominique , Demetter Pieter , Cuvelier Claude A. , Kruithof Elli , Van Damme Nancy , De Vos Martine , Veys Eric M. , De Keyser Filip 
Published: October 2002

AbstractThe objective of this study was to investigate CD163+ macrophages in the synovial membrane of patients with spondyloarthropathy (SpA). Immunohistochemistry was performed on synovium of 17 SpA and 18 rheumatoid arthritis (RA) patients, on colonic biopsies of 16 SpA patients and ten healthy controls, and on paired synovial biopsies of eight SpA patients, before and after anti‐TNFα therapy. Phenotype and cytokine production were analysed by flow cytometry. CD163+ macrophages were increased in the synovial lining and sublining in SpA versus RA, as well as in colonic lamina propria in SpA versus controls. The number of CD163+ macrophages in the synovial sublining correlated with C‐reactive protein levels and erythrocyte sedimentation rate. Paralleling the increase of CD163, HLA‐DR was increased in the synovial lining and sublining of SpA. In contrast, the co‐stimulatory molecules CD80 and CD86 and the dendritic cell markers CD1a and CD83 were scarce in SpA synovium. Flow cytometry indicated that CD163+ macrophages expressed high levels of HLA‐DR and could produce in vitro tumour necrosis factor α (TNFα) but not interleukin‐10 (IL‐10). Finally, anti‐TNFα therapy in vivo induced a decrease of CD163+ macrophages in the synovial lining and sublining. In conclusion, macrophages expressing the scavenger receptor CD163 are increased in synovium and in colonic mucosa in SpA, highlighting the relationship between joint and gut in this disease. The correlation with inflammatory parameters, the expression of HLA‐DR, the production of TNFα but not IL‐10, and the reduction by anti‐TNFα therapy support a role for CD163+ macrophages in the synovial inflammation in SpA. Copyright © 2002 John Wiley & Sons, Ltd.
Involvement of the Fas/FasL pathway in the pathogenesis of germ cell tumours of the adult testis
Authors: Kersemaekers Anne‐Marie F. , van Weeren Pascale C. , Wolter Oosterhuis J. , Looijenga Leendert H. J. 
Published: October 2002

AbstractInduction of apoptosis by Fas ligand (FasL) of Fas‐containing cells is a known mechanism involved in the eradication of inappropriate cells during normal development. Alterations of the Fas/FasL pathway have been found in various types of cancer, leading to circumvention of attack of the tumour by the immune system. An alternative way to circumvent eradication by induction of apoptosis is through changes in the downstream inhibitors. For example, Fas‐associating phosphatase‐1 (Fap‐1) binds directly to the Fas receptor and results in a block of the downstream signalling. To shed more light on the role of the Fas/FasL pathway in the development of human testicular germ cell tumours of the adult testis, this study investigated the presence of Fas, FasL, Fap‐1, HLA class I and II molecules, CD45 (lymphocyte marker), and CD57 [natural killer (NK) cell marker] by immunohistochemistry on frozen sections of 41 cases of seminomas, non‐seminomas, and spermatocytic seminomas. Every germ cell tumour was positive for Fap‐1 and negative for HLA classes I and II, like their non‐malignant cells of origin. The infiltrating lymphocytes, predominantly present in seminomas, showed consistently positive staining for Fas and CD45, but not for Fap‐1. No Fas was found on NK cells. All seminomas and non‐seminomas (except teratomas), including their precursor stages, carcinoma in situ, intratubular seminoma and intratubular non‐seminoma, showed positive staining for FasL, but not for Fas. Teratoma showed no staining for FasL and was positive for Fas. In contrast, both Fas and FasL were detectable on spermatocytic seminoma. These data indicate a different regulation of the Fas/FasL system in seminoma and spermatocytic seminoma, supporting a separate pathogenesis for these germ cell‐derived tumours. The presence of Fap‐1 in all histological variants of germ cell tumours might be related to the consistently positive staining in cells of the germ lineage. This study indicates that production of FasL by the germ cell tumour cells might be involved in the early development of these types of adult testicular cancer by inducting apoptosis of Fas‐positive, Fap‐1‐negative tumour‐infiltrating lymphocytes. Copyright © 2002 John Wiley & Sons, Ltd.