bluuebunny/crossref_metadata_2025 huggingface dataset:
Shape sensitivity of a plane crack front
Authors: Kovtunenko Victor A.
Published: March 2003

The 3D‐elasticity model of a solid with a plane crack under the stress‐free boundary conditions at the crack is considered. We investigate variations of a solution and of energy functionals with respect to perturbations of the crack front in the plane. The corresponding expansions at least up to the second‐order terms are obtained. The strong derivatives of the solution are constructed as an iterative solution of the same elasticity problem with specified right‐hand sides. Using the expansion of the potential and surface energy, we consider an approximate quadratic form for local shape optimization of the crack front defined by the Griffith criterion. To specify its properties, a procedure of discrete optimization is proposed, which reduces to a matrix variational inequality. At least for a small load we prove its solvability and find a quasi‐static model of the crack growth depending on the loading parameter. Copyright © 2003 John Wiley & Sons, Ltd.
The Milne problem for the linear Fokker–Planck operator with a force term
Authors: Lucquin‐Desreux Brigitte
Published: March 2003

This paper deals with the mathematical analysis of the linear stationary Fokker–Planck equation in a half‐space (also called ‘Milne’ problem), in presence of an external electrostatic force field. We prove existence, uniqueness and asymptotic properties of the solution. Copyright © 2003 John Wiley & Sons, Ltd.
Combined far‐ield operators in electromagnetic inverse scattering theory
Authors: Cakoni Fioralba , Colton David
Published: March 2003

We consider the inverse scattering problem of determining the shape of a perfect conductor D from a knowledge of the scattered electromagnetic wave generated by a time‐harmonic plane wave incident upon D. By using polarization effects we establish the validity of the linear sampling method for solving this problem that is valid for all positive values of the wave number. We also show that it suffices to consider incident directions and observation angles that are restricted to a limited aperture. Copyright © 2003 John Wiley & Sons, Ltd.
Leaky and surface waves in multilayered laterally‐shielded microstrip transmission lines
Authors: Gómez Tornero J. L. , Álvarez Melcón A.
Published: March 2003

In this paper the leakage effects in open laterally‐shielded multilayered microstrip transmission lines are investigated. Potential solutions are often reported to be difficult to find, since they are located in the complex propagating factor plane. To overcome this problem, a novel iterative algorithm is implemented to relate the solutions in the real axis of closed transmission lines with their corresponding complex open structure modes. The problem of modeling the leaky behavior of the open top wall is introduced, and a mathematical and physical explanation of the solutions is proposed. The advantage of this new technique is that it allows us to easily track the leaky solutions to their final location in the complex plane. Results are presented, including the field and power patterns associated to leaky waves, showing that the derived technique is indeed effective for the study of the complex modes excited in this type of structures. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 88–93, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10832
Artificial neural networks for calculating the input resistance of circular microstrip antennas
Authors: Guney Kerim , Sarıkaya Nurcan
Published: March 2003

A method based on artificial neural networks (ANNs) for calculating the input resistance of circular microstrip patch antennas is presented. The Levenberg–Marquardt algorithm is used to train the networks. The theoretical input resistance results obtained by using this method are in very good agreement with the experimental results available in the literature. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 107–111, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10838
Small helical antenna for the applications of the dual ISM bands
Authors: Wang Chien‐Jen
Published: March 2003

A new design of a miniaturized multilayer ceramic (MLC) antenna is proposed and presented for the applications of the dual ISM bands (hyper LAN and WLN). The antenna‐size reduction is achieved by folding the simple microstrip monopole around a low‐temperature co‐fired ceramic (LTCC) substrate. This paper presents measured data to show that the 10‐dB bandwidths achieved were 180 MHz and 750 MHz at 2.4 GHz and 5.2 GHz, respectively. The co‐polarization far‐field radiation patterns of the chip antenna are quasi‐omnidirectional at 2.4 GHz and 5.2 GHz. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 140–142, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10848
Theoretically obtained dispersion characteristics of an annular waveguide with a guiding region cross section bounded by two hypocycloidal loops
Authors: Singh Vivek , Prasad B. , Ojha S. P.
Published: March 2003

This article presents a theoretical analysis of the modal dispersion curves of an annular waveguide with a core cross section bounded by two hypocycloids. This cross section can be conceived as having the shape of a distorted annular square and leads to a tolerance study of deformation in an annular square waveguide. We take a new and appropriate coordinate system (ξ, η, z) for the proposed geometry and impose boundary conditions under the weak guidance approximation. The characteristic equation is then derived analytically. Finally, we show some numerical results in the form of modal dispersion curves. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 142–145, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10849
Fiber Bragg grating accelerometer with temperature insensitivity
Authors: Zhu Yinian , Shum Ping , Lu Chao , Lacquet Beatrys M. , Swart Pieter L. , Spammer Stephanus J.
Published: March 2003

A cantilever beam and fiber Bragg grating are used to measure acceleration. The output signal is insensitive to temperature variations from −20°C to 40°C, and the output signal fluctuates less than 5% without any temperature compensation schemes. For the experimental system, a linear output range of 8 g can be detected. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 151–153, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10852
Isolation and spectral study of 4‐methyl‐6,8‐dihydroxy‐7H‐benz[de]anthracen‐7‐one
Authors: Wang H. M. , Shi W. , Xu Y. K. , Wang P. , Chen W. , Liu Y. , Lü M. J. , Pa J. Q.
Published: March 2003

4‐Methyl‐6,8‐dihydroxy‐7H‐benz[de]anthracen‐7‐one was isolated from the sap of Aloe by column chromatography. Its 1H and 13C NMR spectra were completely assigned by utilizing two‐dimensional 1H‐detected heteronuclear one‐bond (HMQC) and multiple‐bond (HMBC) chemical shift correlation experiments together with 1H–1H COSY and DEPT techniques. These techniques were also valuable in assigning the protons and carbons of those benzanthrone compounds which were previously incompletely reported because of the overlap of proton signals. The molecular structure was elucidated by 2D NMR analysis. The spectral properties (MS, IR and UV) are also presented. Copyright © 2003 John Wiley & Sons, Ltd.
Indirect detection of 31P,X connectivities with proton sensitivity: application of two‐dimensional 31P‐relayed 1H,X correlation spectroscopy
Authors: Gudat Dietrich
Published: March 2003

Experiments for 1H‐detected heteronuclear 1H,X correlation spectroscopy with 31P‐relayed coherence transfer are described which allow the indirect detection of δX and nJ(X,P) even in the absence of a direct J(X,H) coupling. The use of these techniques for the assignments of 13C, 15N, and 183W NMR data of organophosphorus compounds is demonstrated. Copyright © 2003 John Wiley & Sons, Ltd.
Complete structural and spectral assignment of oxoisoaporphines by HMQC and HMBC experiments
Authors: Sobarzo‐Sánchez Eduardo , Cassels Bruce K. , Jullian Carolina , Castedo Luis
Published: March 2003

The oxoisoaporphines 2,3‐dihydro‐7H‐dibenzo[de,h]quinolin‐7‐one, 2,3‐dihydro‐5‐methoxy‐7H‐dibenzo [de,h] quinolin‐7‐one, 5‐methoxy‐6‐hydroxy‐2,3‐dihydro‐7H‐dibenzo[de,h]quinolin‐7‐one, 5,6‐dimethoxy‐2,3‐dihydro‐7H‐dibenzo[de,h]quinolin‐7‐one and 5,6‐methylenedi‐oxy‐2,3‐dihydro‐7H‐dibenzo[de,h]quinolin‐7‐one were prepared by cyclization of phenylethylaminophthalides with polyphosphoric acid or by treating 1‐(2‐carboxyphenyl)‐3,4‐dihydroisoquinoline hydrochloride with sulfuric acid at 0 °C. The structures were confirmed and 1H and 13C NMR spectra were completely assigned using a combination of one‐ and two‐dimensional NMR techniques. Copyright © 2003 John Wiley & Sons, Ltd.
Evaluation and treatment of low back pain: An evidence‐based approach to clinical care
Authors: Atlas Steven J. , Nardin Rachel A.
Published: March 2003

Low back pain is a common reason for patient visits to a health care provider. For most patients, low back symptoms are nonspecific, meaning that the pain is localized to the back or buttocks and is due to a presumed musculoligamentous process. For patients with radicular leg symptoms, a precise etiology is more commonly identified. The history and physical examination usually provide clues to the uncommon but potentially serious causes of low back pain, as well as to those patients at risk for prolonged recovery. Diagnostic testing should not be a routine part of the initial evaluation, but used selectively based upon the history, examination, and initial treatment response. For patients without significant neurological impairment, initial treatments should include activity modification, nonnarcotic analgesics, and education. For patients whose symptoms are not improving over 2 to 4 weeks, referral for physical treatments is appropriate. A variety of therapeutic options of limited or unproven benefit are available for patients with radicular leg symptoms or chronic low back pain. Patients with radicular pain and little or no neurological findings should receive conservative treatment, but elective surgery is appropriate for those with nerve root compression who are unresponsive to conservative therapy. Muscle Nerve 27: 265–284, 2003
Myopodia (postsynaptic filopodia) participate in synaptic target recognition
Authors: Ritzenthaler Sarah , Chiba Akira
Published: March 2003

Synaptic partner cells recognize one another by utilizing a variety of molecular cues. Prior to neuromuscular synapse formation, Drosophila embryonic muscles extend dynamic actin‐based filopodia called “myopodia.” In wild‐type animals, myopodia are initially extended randomly from the muscle surface but become gradually restricted to the site of motoneuron innervation, a spatial redistribution we call “clustering.” Previous experiments with prospero mutant embryos demonstrated that myopodia clustering does not occur in the absence of motoneuron outgrowth into the muscle field. However, whether myopodia clustering is due to a general signal from passing axons or is a result of the specific interactions between synaptic partners remained to be investigated. Here, we have examined the relationship of myopodia to the specific events of synaptic target recognition, the stable adhesion of synaptic partners. We manipulated the embryonic expression of αPS2 integrin and Toll, molecules known to affect synaptic development, to specifically alter synaptic targeting on identified muscles. Then, we used a vital single‐cell labeling approach to visualize the behavior of myopodia in these animals. We demonstrate a strong positive correlation between myopodia activity and synaptic target recognition. The frequency of myopodia clustering is lowered in cases where synaptic targeting is disrupted. Myopodia clustering seems to result from the adherence of a subset of myopodia to the innervating growth cone while the rest are eliminated. The data suggest that postsynaptic cells play a dynamic role in the process of synaptic target recognition. © 2003 Wiley Periodicals, Inc. J Neurobiol 55: 31–40, 2003
Differential physiologic responses of α7 nicotinic acetylcholine receptors to β‐amyloid1–40 and β‐amyloid1–42
Authors: Lee Daniel H.S. , Wang Hoau‐Yan
Published: March 2003

The β‐amyloid peptides (Aβ), Aβ1–40 and Aβ1–42, have been implicated in Alzheimer's disease (AD) pathology. Although Aβ1–42 is generally considered to be the pathological peptide in AD, both Aβ1–40 and Aβ1–42 have been used in a variety of experimental models without discrimination. Here we show that monomeric or oligomeric forms of the two Aβ peptides, when interact with the neuronal cation channel, α7 nicotinic acetylcholine receptors (α7nAChR), would result in distinct physiologic responses as measured by acetylcholine release and calcium influx experiments. While Aβ1–42 effectively attenuated these α7nAChR‐dependent physiology to an extent that was apparently irreversible, Aβ1–40 showed a lower inhibitory activity that could be restored upon washings with physiologic buffers or treatment with α7nAChR antagonists. Our data suggest a clear pharmacological distinction between Aβ1–40 and Aβ1–42. © 2003 Wiley Periodicals, Inc. J Neurobiol 55: 25–30, 2003
Prefiltration technique via aggregation for constructing low‐density high‐quality factorized sparse approximate inverse preconditionings
Authors: Nikishin A. A. , Yeremin A. Yu.
Published: March 2003

This paper considers a new approach to a priori sparsification of the sparsity pattern of the factorized approximate inverses (FSAI) preconditioner using the so‐called vector aggregation technique. The suggested approach consists in construction of the FSAI preconditioner to the aggregated matrix with a prescribed sparsity pattern. Then small entries of the computed ‘aggregated’ FSAI preconditioning matrix are dropped, and the resulting pointwise sparsity pattern is used to construct the low‐density block sparsity pattern of the FSAI preconditioning matrix to the original matrix. This approach allows to minimize (sometimes significantly) the construction costs of low‐density high‐quality FSAI preconditioners. Numerical results with sample matrices from structural mechanics and thin shell problems are presented. Copyright © 2002 John Wiley & Sons, Ltd.
Strongly non‐local gradient‐enhanced finite strain elastoplasticity
Authors: Geers M. G. D. , Ubachs R. L. J. M. , Engelen R. A. B.
Published: March 2003

This paper presents a gradient plasticity formulation developed in a strongly non‐local format and applicable to ductile failure for finite strain plasticity. The obtained formulation is an extension of a framework proposed by Simo (Computer Methods in Applied Mechanics and Engineering 1988; 66: 199) into the softening and localization regime. The presented model inherits the well‐established regularization properties of its strongly non‐local enrichment and leads to an implicit computational scheme with a consistent tangent operator. Numerical examples are given which illustrate the strongly non‐local character of the formulation, the influence of the type of intrinsic length scale considered, as well as several topics on plastic failure initiation and evolution into the geometrically non‐linear regime. Copyright © 2003 John Wiley & Sons, Ltd.
An analysis of strain localization in a shear layer under thermally coupled dynamic conditions. Part 1: Continuum thermoplastic models
Authors: Armero F. , Park J.
Published: March 2003

The work presented in this two‐part paper investigates the characteristics of strain localization in a one‐dimensional shear layer with thermomechanical softening behaviour. We consider in this first part the case of a classical continuum model characterized with a stress–strain relation incorporating the inelastic effects through plastic strains. The thermomechanical coupling effects in the infinitesimal shear problem of interest here include the thermal softening of the material with the increase of the temperature, and the heat source generated by the plastic work in the equation of conservation of energy. We first present a spectral analysis of the linearized problem, characterizing its stability and well‐posedness. We consider the general problem including a viscoplastic regularization in this coupled thermomechanical context, without neglecting the elastic effects. This analysis identifies, in particular, the ill‐posedness of the local continuum model under certain conditions, most notably in the inviscid problem with strain softening. The coupled thermal effects are shown then not to regularize the coupled problem in these circumstances. The lack of an internal length scale associated with the strain localization is concluded. The analytical closed‐form solution of the full non‐linear problem is also presented for the identified ill‐posed problems, revealing the lack of physical significance of these models in these cases. The implications of this analysis for the finite element simulations in the form of pathologically mesh‐size dependent solutions is also concluded and illustrated with a number of representative numerical simulations. Copyright © 2003 John Wiley & Sons, Ltd.
Effect of particle cracking on elastoplastic behaviour of metal matrix composites
Authors: Sun L. Z. , Liu H. T. , Ju J. W.
Published: March 2003

A micromechanics‐based elastoplastic and damage constitutive model is proposed to predict the overall mechanical behaviour of particle‐reinforced metal matrix composites. Unidirectionally aligned spheroidal elastic particles, some of which contain penny‐shaped cracks, are randomly distributed in the elastoplastic metal matrix. These imperfect particles, attributed to progressive particle cracking, are modelled by using the double‐inclusion concept. An ensemble‐volume averaged homogenization procedure is employed to estimate the effective yield function of the damaged composites. The associative plastic flow rule and the hardening law are postulated based on the continuum plasticity theory. The underlying damage evolution of particles is considered in accordance with the Weibull's statistical function to characterize the varying probability of reinforcement cracking. The elastoplastic mechanical behaviour of particulate composites under uniaxial loading conditions is simulated and compared with available experimental results. Copyright © 2003 John Wiley & Sons, Ltd.
Failure analysis of solder joints with a damage‐coupled viscoplastic model
Authors: Wei Y. , Chow C. L. , Neilsen M. K. , Fang H. E.
Published: March 2003

This paper presents failure analysis of solder joints with a damage‐coupled viscoplastic model. A material model is developed to characterize the elasticity, plasticity, creep and damage of solder. A semi‐implicit time‐integration approach is adopted for the numerical implementation of the solder model. This solder model has been implemented into finite element codes developed at Sandia National Laboratories and into the commercial, finite element code ABAQUSTM with its user‐defined material subroutine UMAT. Finite element analyses are performed on solder joints with the new solder constitutive model and mesh dependency of these analyses is investigated. Copyright © 2003 John Wiley & Sons, Ltd.
Time finite elements and error computation for (visco)plasticity with hardening or softening
Authors: Larsson Fredrik , Runesson Kenneth , Hansbo Peter
Published: March 2003

In this paper we investigate the possibility for, and characteristics of, reliable and efficient a posteriori error computation at the integration of the constitutive relations pertinent to (visco)plasticity with softening/hardening. The variational structure admits the use of finite elements in time, which are based on the Discontinuous Galerkin method. An important feature is the possibility to select ‘goal‐oriented’ error measures with great freedom. A key task is to identify and solve an auxiliary problem, that is the dual of the actual (primal) problem. Different strategies for computing the dual solution accurately, yet avoiding excessive cost, are investigated in the paper. In particular, we consider the characteristics at the limit of rate‐independent plasticity. Copyright © 2003 John Wiley & Sons, Ltd.
Dose‐dependence of the effect of nicotine on c‐Fos expression in the hippocampus of young rats
Authors: Jang Mi‐Hyeon , Shin Min‐Chul , Kim Hong , Kim Ee‐Hwa , Kim Chang‐Ju
Published: March 2003

It is generally accepted that nicotine affect learning ability and memory functions, especially during adolescence. c‐Fos is an immediate early gene whose expression is sometimes used as a marker for stimulation‐induced changes in the metabolic activity of neurons. The expression of c‐Fos is induced by a variety of stimuli and expression of c‐fos mRNA in hippocampal regions is used as a marker for neuronal activity. In the present study, the effect of dose‐dependence of the nicotine on the c‐Fos expression in the hippocampus of young rats was investigated via immunohistochemistry. From the present results, the number of Fos‐positive cells in each region of the hippocampus was decreased following treatment with nicotine as dose‐dependently. In addition, it appears that nicotine at low doses does not affect the level of apoptosis in the dentate gyrus of the hippocampus; in contrast, nicotine at high doses seems to enhance apoptosis in the dentate gyrus. Based on the results, it can be suggested that nicotine‐induced suppression on Fos expression in the hippocampus of young rats may be an underlying mechanism of nicotine‐induced disruption of information processing during the adolescence.
The weighted Ritz‐Galerkin method for elliptic boundary value problems on unbounded domains
Authors: Oh Hae‐Soo , Jang Bongsoo , Jou Yichung
Published: March 2003

Recently Babus̆ka‐Oh introduced the method of auxiliary mapping (MAM) which efficiently handles elliptic boundary value problems containing singularities. In this paper, a special weighted residue method, the Weighted Ritz‐Galerkin Method (WRGM), is investigated by introducing special weight functions. Together with this method, MAM is modified to yield highly accurate finite element solutions to general elliptic boundary value problems on the exterior of bounded domains at low cost. © 2003 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 19: 301–326, 2003.
The use of client surveys to gauge the threat of contamination in welfare reform experiments
Authors: Camasso Michael J. , Jagannathan Radha , Harvey Carol , Killingsworth Mark
Published: March 2003

This paper examines the type of evidence policy analysts have used to identify the presence and magnitude of contamination in welfare reform experiments. Peter Rossi's critique of the New Jersey Family Development Program evaluation motivates the following discussion. In this critique Rossi and others contend that client misperception about experimental control‐group assignment resulted in contamination that negates reported treatment effectiveness. By applying the framework of the Rubin Causal Model (RCM) to isolate “pure” and “impure” experimental and control cases, the actual group assignment and not self‐reported membership is shown to be a more accurate gauge of treatment level and effect. The analysis reveals that the form of contamination Rossi detected leads to underestimates of treatment effects, not their evaporation. While contamination is a legitimate threat in any research design its identification must be based on empirical measures. © 2003 by the Association for Public Policy Analysis and Management.
Managing contract performance: A transaction costs approach
Authors: Brown Trevor L. , Potoski Matthew
Published: March 2003

Managing contracts is a complex process, often exacerbated by high transaction costs inherent in negotiating, implementing, and monitoring contract relationships with vendors. Through analyses of data from a 1997 International City/County Management Association survey of municipal and county governments, the way in which municipal and county governments respond to transaction cost factors inherent in contract service delivery is examined. The results of the analyses demonstrate that when governments contract for services in contexts that risk contract failure, they engage in a variety of monitoring techniques to improve their ability to monitor and correct vendor performance. © 2003 by the Association for Public Policy Analysis and Management.
Guanidine hydrochloride extraction and detection of prion proteins in mouse and hamster prion diseases by ELISA
Authors: Kang Shin‐Chung , Li Ruliang , Wang Chuanping , Pan Tao , Liu Tong , Rubenstein Richard , Barnard Geoff , Wong Boon‐Seng , Sy Man‐Sun
Published: March 2003

Current detection of transmissible spongiform encephalopathy (TSE) relies on the proteolytic generation of a protease‐resistant core from the scrapie isoform of prion protein (PrPSc) followed by immunoblotting. This process is non‐quantitative, time‐consuming, and technically demanding. Recently, an alternative in vitro test for TSE based on the differential extraction of brain homogenates using guanidine hydrochloride followed by DELFIA (Dissociation Enhanced Lanthanide FluoroImmunoAssay) has been developed. In the present study, this approach was adopted using a panel of anti‐PrP monoclonal antibodies (MAbs) in conventional sandwich enzyme‐linked immunosorbent assay (ELISA) to investigate hamster and two distinct strains of mouse prion diseases. Although PrP species were present in both soluble and insoluble fractions from normal as well as TSE samples, only the PrP species in the insoluble fractions from the latter samples were protease‐resistant. In addition, certain anti‐PrP MAb pairs could distinguish the PrP species in infected brains from those in the normal samples. The ability to differentiate disease‐associated PrP isoforms without proteinase K digestion could serve as a panacea for developing a reliable and rapid diagnostic test for prion diseases. Copyright © 2003 John Wiley & Sons, Ltd.
Abnormalities of E‐ and P‐cadherin and catenin (β‐, γ‐catenin, and p120ctn) expression in endometrial cancer and endometrial atypical hyperplasia
Authors: Moreno‐Bueno Gema , Hardisson David , Sarrió David , Sánchez Carolina , Cassia Raúl , Prat Jaime , Herman James G , Esteller Manel , Matías‐Guiu Xavier , Palacios José
Published: March 2003

Abnormal expression of cadherins and catenins plays a critical role in the initiation and progression of multiple human tumours. This study aimed to evaluate the immunoreactivity of E‐ and P‐cadherin, β‐ and γ‐catenin, and p120ctn in premalignant and malignant endometrial lesions and to correlate their membranous expression with clinicopathological features. In addition, we examined whether or not LOH and promoter hypermethylation of the CDH1 gene were associated with E‐cadherin expression and clinicopathological variables. Finally, we studied the frequency of β‐catenin mutations in premalignant endometrial lesions. Immunohistochemical staining was performed in 21 atypical endometrial hyperplasias (AEHs), 95 endometrioid carcinomas (EECs), and 33 non‐endometrioid carcinomas (NEECs). Reduced E‐cadherin expression was observed in 57.8% of the cases, being more frequent in NEECs (87.1%, p = 0.001) and carcinomas of more advanced stage (85.7% of stage III–IV carcinomas, p = 0.01). LOH of CDH1 gene was found in 57.1% of NEECs but only in 22.5% of EECs (p = 0.011) and showed a trend towards association with reduced E‐cadherin expression (p = 0.089). CDH1 promoter hypermethylation was found in 21.2% of endometrial carcinomas but was not associated with clinicopathological or immunohistochemical variables. Reduced expression of β‐ and γ‐catenin and p120ctn was found in 76.1%, 94.3%, and 63.6% of the cases, respectively, being more frequent in lesions with reduced E‐cadherin expression. In addition, β‐catenin, but not γ‐catenin or p120ctn expression, was associated with the histology of the lesion, since it was reduced in 35% of AEHs, 80.3% of EECs, and 96.9% of NEECs (p = 0.000). Mutations in exon 3 of the β‐catenin gene, associated with β‐catenin nuclear expression, were detected in 3 (14.0%) AEH, a frequency similar to that previously reported in this series of ECs. Finally, upregulation of P‐cadherin was observed in 28.6% of cases. This alteration was associated with the histology of the lesion, since it was found in 9.5% of AEHs, 27.7% of EECs, and 46.2% of NEECs (p = 0.021). Copyright © 2003 John Wiley & Sons, Ltd.
Elevated telomerase activity, c‐MYC‐, and hTERT mRNA expression: association with tumour progression in malignant lipomatous tumours
Authors: Schneider‐Stock Regine , Boltze Carsten , Jäger Viola , Epplen Jörg , Landt Olfert , Peters Brigitte , Rys Janusz , Roessner Albert
Published: March 2003

The role of telomerase activity in tumour progression of liposarcomas is not well understood. Therefore, we investigated 72 liposarcomas of different histological subtypes for an association between telomeric lengths and telomerase activity, and assessed the association between the catalytic subunit human telomerase reverse transcriptase (hTERT) and its activator c‐MYC. Telomeric repeat fragment lengths were determined using radioactive DNA–fingerprint analysis with the telomere‐specific probe (TTAGGG)3, whereas telomerase activity was ascertained using the non‐radioactive TRAP‐assay. To evaluate the expression of hTERT and c‐MYC, we applied real‐time RT‐PCR using a LightCycler. Eight tumours were investigated by microdissection. The MIB1‐proliferation index and hTERT and c‐MYC protein expression were determined immunohistochemically. Genetic alterations showed a high degree of tumour specificity. Highly malignant myxoid/round cell liposarcomas showed the longest telomeres, the strongest telomerase activity, and the highest hTERT and c‐MYC expression levels compared with the pure myxoid variants (p < 0.001), which are of low malignancy. Pleomorphic liposarcoma was characterized by zero or low hTERT and c‐MYC expression and telomerase activity, but long telomeres, underlining their different pathogenetic pathway. Elevated gene expression was accompanied by protein immunopositivity. MIB1‐proliferation index did not correlate with other molecular markers. We conclude that hTERT and c‐MYC expression are associated with telomerase activity in liposarcomas. Elevated hTERT and c‐MYC expression as well as high telomerase activity play a role in the tumour progression of this sarcoma type. Nevertheless, each histological subtype of liposarcomas is defined by a specific molecular pattern. Telomerase activation is the most common pathway in liposarcomas maintaining telomeric length. Copyright © 2003 John Wiley & Sons, Ltd.
Expression of cyclins E, A, and B, and prognosis in lymph node‐negative breast cancer
Authors: Kühling Heidi , Alm Per , Olsson Håkan , Fernö Mårten , Baldetorp Bo , Parwaresch Reza , Rudolph Pierre
Published: March 2003

Unexpected outcomes in breast cancer demand a refinement of prognostic criteria. This study therefore investigated the prognostic relevance of cyclin expression in a cohort of 332 T1–T2 N0 infiltrating ductal carcinomas with long‐term follow‐up (median 99 months). By univariate analysis, tumour size, histopathological grade, hormone receptor content, cyclin E, cyclin B, and the Ki‐S5 (Ki‐67) index significantly predicted disease‐specific and metastasis‐free survival. Cyclin A did not achieve statistical significance. In a multivariate analysis, both cyclin E [relative risk (RR) 2.01, p = 0.021] and cyclin B (RR 1.85, p = 0.033) were selected as independent prognosticators of metastasis‐free survival when the Ki‐67 index was omitted, but only cyclin E expression was associated with disease‐specific survival (RR 2.56, p = 0.006). When Ki‐67 was included as a covariate, cyclin E lost its significance with respect to disease‐specific survival but remained significant for metastasis‐free survival. In an analogous analysis including Ki‐67, the number of concurrently overexpressed cyclins did not attain statistical significance regarding disease‐specific survival but was selected as the leading predictor of metastatic disease. It is concluded that combined overexpression of cyclins may imply genetic instability enhancing metastatic potential, but that survival ultimately depends on the proliferative activity of tumour cells. Copyright © 2003 John Wiley & Sons, Ltd.
Neue vielversprechende Antimykotika
Authors: Zündorf I.
Published: March 2003

Zwei neue Echinocandine stehen kurz vor der Zulassung durch die amerikanische FDA
Was macht Krebs aggressiv?
Authors: Gießen Hannelore
Published: March 2003

Ob sich ein Tumor bildet, hängt auf genetischer Ebene von Onkogenen, Tumor‐Suppressor‐Genen und DNA‐Reparaturgenen ab. Wie vehement eine Krebserkrankung jedoch verläuft, wird auch von der Rezeptorvariante für einen Wachstumsfaktor beeinflusst, die Wissenschaftler am Max‐Planck‐Institut für Biochemie in Martinsried entdeckt haben.
Arrays überall
Authors: Holzgrabe Ulrike
Published: March 2003

Von Chips für die Analyse von DNA und Proteinen wird im Augenblick überall berichtet. So wundert es nicht, dass man auch versucht, G‐Protein‐gekoppelte Rezeptoren (GPCR) auf einen Chip zu bannen, um möglichst schnell die Affinität und Selektivität neu synthetisierter potenzieller Wirkstoffe zu evaluieren.
Neues zum alten Histamin II. Ionenkanäle in Drosophila
Authors: Stark Holger
Published: March 2003

Es ist seit längerem bekannt, dass wichtige Neurotransmitterfunktionen bei Insekten über Histamin gesteuert werden. Die Entdeckung histamingesteuerter Chloridionen‐Kanäle verspricht Ansätze zu neuen Insektiziden.
Replicate real‐time PCR testing of DNA in maternal plasma increases the sensitivity of non‐invasive fetal sex determination
Authors: Hromadnikova Ilona , Houbova Bela , Hridelova Dana , Voslarova Sona , Kofer Josef , Komrska Vladimir , Habart David
Published: March 2003

Background

We determined fetal sex in pregnancies referred for invasive prenatal diagnosis procedures by analysis of DNA in maternal plasma.

Methods

Twelve pregnancies at risk of X‐linked haemophilia and 32 pregnancies at risk of chromosomal aneuploidies at a gestational age ranging from 10 to 18 weeks recruited before chorionic villus sampling or amniocentesis were involved in the study. Male fetal DNA in maternal plasma was detected by using real‐time polymerase chain reaction with the SRY gene as a marker.

Results

The specificity of the system reached 100% (no Y signal was detected in 17 women pregnant with a female fetus) and the sensitivity reached 100% (SRY amplification in 27 examined samples).

Conclusions

Amplification of free fetal DNA in maternal plasma is a valid and rapid technique for predicting fetal sex in first‐ and second‐trimester pregnancies and could allow the restriction of invasive sampling procedures to male fetuses at risk of X‐linked disorders. Copyright © 2003 John Wiley & Sons, Ltd.
Idiopathic fetal intrauterine growth restriction: a possible inheritance pattern
Authors: Ghezzi Fabio , Tibiletti Maria Grazia , Raio Luigi , Di Naro Edoardo , Lischetti Barbara , Taborelli Monica , Franchi Massimo
Published: March 2003

Objective

This study was conducted to assess if the delivery of a previous growth‐retarded (IUGR) fetus increases the risk of having an IUGR fetus in subsequent pregnancies and to explore if a familial pattern of transmission is involved.

Methods

Seventy consecutive multiparous women whose fetus was IUGR (group 1) and 70 controls (group 2) were enrolled in this study.

Results

The proportion of women who developed preeclampsia (9 versus 2, p = 0.05) and who had delivered an IUGR fetus in a previous pregnancy (20 versus 4, p < 0.05) were higher in group 1 than in group 2. There was no difference in the incidence of chronic hypertension, diabetes, smoking, substance or alcohol abuse, and HIV infection between the groups. After adjustment for preeclampsia, the delivery of a previous IUGR fetus remained a risk factor for having a subsequent IUGR fetus [Odds ratio = 6.7 (CI 2.15–21.22), p < 0.01]. Pedigree analysis conducted in 15 families revealed a familial cluster of IUGR infants in all families that were investigated. In 9 out of 15 families, a dominant pattern of inheritance of IUGR was observed while the remaining families were more heterogeneous. In one family, a balanced carrier of chromosome 7 inversion generated a malformed fetus and two IUGR infants.

Conclusions

This study clarifies that IUGR may be an inherited genetic condition and emphasizes that a knowledge of the family history and of the parental karyotype may be helpful in the prevention of both fetal malformations and adverse neonatal morbidity in subsequent low birth weight infants. Copyright © 2003 John Wiley & Sons, Ltd.
Maternal serum–integrated screening for trisomy 18 using both first‐ and second‐trimester markers
Authors: Palomaki Glenn E. , Neveux Louis M. , Knight George J. , Haddow James E.
Published: March 2003

Objectives

To estimate the prenatal screening performance of an integrated serum test for detecting trisomy 18, which combines measurements of first‐ and second‐trimester markers with maternal age to assign patient‐specific risks.

Methods

Published and new observations of maternal serum marker levels in trisomy 18 and unaffected pregnancies are used to derive population parameters. These parameters are then combined in a multivariate Gaussian model to assign patient‐specific risks for trisomy 18.

Results

The best combination of serum markers includes pregnancy‐associated plasma protein‐A in the first trimester and alpha‐fetoprotein, unconjugated estriol and human chorionic gonadotropin in the second trimester. At a second‐trimester risk cutoff of 1 : 100, these 4 markers, in combination with maternal age, detect 90% of trisomy 18 pregnancies at a false‐positive rate of 0.1%. The odds of a trisomy 18 pregnancy among screen‐positive women are 1 : 4. Without the first‐trimester marker, detection is reduced to 67% at about the same false‐positive rate.

Conclusion

The algorithm described here is highly efficient for detecting trisomy 18 and should be considered by programs that offer serum‐integrated screening for Down syndrome. Copyright © 2003 John Wiley & Sons, Ltd.
Modelling a monolithically integrated vertical junction cell in low and high injection
Authors: Catchpole K. R. , Blakers A. W. , Weber K. J.
Published: March 2003

A monolithic vertical junction cell design suitable for high‐quality lifted‐off silicon films is modelled and the factors influencing the efficiency are investigated. The structure has a high efficiency potential and could potentially be manufactured with a simple process. An interesting effect is described which leads to a higher short‐circuit current in high injection than in low injection in certain circumstances, and the reason for the increase is explained. Copyright © 2002 John Wiley & Sons, Ltd.
Suprafluidität — Von den Schwierigkeiten einer Messung
Authors: Sichau Christian
Published: March 2003

Der Vater der Tieftemperaturphysik, Heike Kammerlingh Onnes, benötigte zu Beginn des 20. Jahrhunderts für die Verflüssigung von wenigen Litern Heliums noch mehrere Jahre, eine riesige Apparatur und viel Geld. Heute gelingt dies routinemäßig. Die Untersuchung der Materie bei tiefen Temperaturen, insbesondere zur Suprafluidität, bietet viele Überraschungen.
A new method to improve sensitivity and resolution in matrix‐assisted laser desorption/ionization time of flight mass spectrometry
Authors: Xiong Shaoxiang , Ding Qinxue , Zhao Zhengwen , Chen Wenzhang , Wang Guanghui , Liu Shaojun
Published: March 2003

High detection sensitivity and resolution are two critical parameters for recording good peptide mass fingerprints (PMF) of low abundance proteins. This paper reports a mass spectrometry (MS) sample preparation technique that could improve sensitivity and resolution. By coating the MS steel target with a thin layer of pentadecafluorooctamido propyltrimethoxysilane, which was both polar and nonpolar solvent repellent, the transferred sample droplets on its surface were significantly smaller. As a result, the analyte of the peptide mixture became more concentrated and homogeneous, which helped to improve the sensitivity. The advantages of a modified MS target were documented by mass spectra improvement of attomole level standard peptides and silver‐stained proteins from polyacrylamide gels. The mass signal of angiotensin II at 100 attomole was difficult to record on the conventional support, whereas it was easily detected on the modified one. The PMF of cytochrome C was also better recorded on the modified support, in terms of both signal‐to‐noise ratio and the number of detected peptides. When silver‐stained proteins from two‐dimensional electrophoresis gels were analyzed, in most cases more satisfactory peptide mass spectra were obtained from the modified support. Searching protein databases with more mass data from the improved PMFs, several unknown proteins were successfully identified.
Wheat proteomics: Relationship between fine chromosome deletion and protein expression
Authors: Islam Nazrul , Tsujimoto Hisashi , Hirano Hisashi
Published: March 2003

To explore the relationship between fine chromosome deletion and protein expression in common wheat, the changes in protein composition of wheat seed proteome were investigated by using chromosome 1B. A momosomic alien chromosome addition line of common wheat was used to produce the fine deletion lines. Endosperm and embryo proteins were separated by two‐dimensional gel electrophoresis (2‐DE) and visualized by staining with Commassie Brilliant Blue, and gel images were analyzed with a computer assisted image analyzer. For the first time, fine gene locations of a few endosperm and embryo proteins were identified on the chromosome 1B. These proteins with their specific gene location on the chromosome can be used as protein markers in breeding programs for quality of wheat proteins. To identify wheat seed proteins and to understand their expression in relation to chromosome deletion, the feasibility of a new analytical approach based on isotope coded affinity tag labeling (ICAT) of peptides in tryptic digests followed by electrospray ionization mass spectrometry has been described. Simplification of the complex tryptic digest prior to mass spectral analysis was performed by treating the samples with light and heavy ICAT labeling reagents. A clear separation of peptide fragment containing the light and heavy reagents was achieved in mass spectral analysis. Out of the 14 peptides detected by mass fragment analysis of the euploid, four were down‐regulated, nine up‐regulated and one did not show any change due to the terminal deletion of chromosome 1B. Selected peptide fragments were subjected to tandem mass spectrometry analysis for sequence information and the resulting sequence information was submitted to databases for protein identification. Of the five proteins submitted, four were identified as alpha‐amylase inhibitor, alpha‐amylase/subtilisin inhibitor precursor, proteasome subunit alpha‐type 7 and 1,4 alpha‐glucan‐D‐maltohydrolase. With this approach it is possible to identify wheat seed proteins and to understand their expression, which have been reported to be difficult by 2‐DE due to cosynthesis of proteins by genes from three genomes, A, B and D.
Proteomic analysis of Lactococcus lactis, a lactic acid bacterium
Authors: Guillot Alain , Gitton Christophe , Anglade Patricia , Mistou Michel‐Yves
Published: March 2003

Lactococcus lactis is a Gram‐positive bacteria, which belongs to the group of lactic acid bacteria among which several genera play an essential role in the manufacture of food products. Cytosolic proteins of L. lactis IL1403 cultivated in M17 broth have been resolved by two‐dimensional gel electrophoresis using two pH gradients (pH 4–7, 4.5–5.5). More than 230 spots were identified by peptide mass fingerprints, corresponding to 25% of the predicted acid proteome. The present study made it possible to describe at the proteome level a significant number of cellular pathways (glycolysis, fermentation, nucleotide metabolism, proteolysis, fatty acid and peptidoglycan synthesis) related to important physiological processes and technological properties. It also indicated that the fermentative metabolism, which characterizes L. lactis is associated with a high expression of glycolytic enzymes. Thirty‐four proteins were matched to open reading frames for which there is no assigned function. The comparison at the proteome level of two strains of L. lactis showed an important protein polymorphism. The comparison of the proteomes of glucose‐ and lactose‐grown cells revealed an unexpected link between the nature of the carbon source and the metabolism of pyrimidine nucleotides.
Bulk hydrosilylation reaction of poly(dimethylsiloxane) chains catalyzed by a platinum salt: Effect of the initial concentration of reactive groups on the final extent of reaction
Authors: Roth Leandro E. , Vallés Enrique M. , Villar Marcelo A.
Published: March 2003

Model silicone networks obtained by curing linear poly(dimethylsiloxane) (PDMS) chains with end‐vinyl groups, (B2), with a polyfunctional silane‐terminated crosslinker of functionality f, (Af), through a hydrosilylation reaction have been widely used. In these networks, the principal characteristics of their ultimate molecular structure are strongly affected by the final extent of reaction reached during the crosslinking reaction. This work analyzes the effect of the initial concentration of the reactive end groups on the maximum attainable extent of reaction under normal bulk crosslinking conditions. This was accomplished by examining the reaction between linear B2 PDMS chains with difunctional and trifunctional silanes. The experimental results were fitted by an exponential equation to have an empirical equation able to predict the maximum extent of reaction to be obtained as a function of the initial concentration of reactive groups. Molecular parameters relevant to this study, such as the degree of polymerization, the weight‐average molecular weight for the A2 + B2 system, or the weight fraction of solubles for the A3 + B2 system, were calculated with a mean field theory (recursive approach). © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1099–1106, 2003
Blue light‐emitting poly(p‐phenylenevinylene) derivatives containing alternating conjugated segments and aliphatic spacers
Authors: Mpallas John G. , Spiliopoulos Ioakim K. , Mikroyannidis John A.
Published: March 2003

Two new poly(p‐phenylenevinylene) derivatives were prepared by Heck coupling. They contained alternating conjugated segments on the basis of p‐distyrylbenzene and flexible nonconjugated spacers. The synthesized polymers P1 and P2 carried two m‐terphenyl of four tertbutyl pendants, respectively, per repeat unit. Both polymers were amorphous and exhibited satisfactory thermal stability. Polymer P1 displayed a limited solubility in common organic solvents, whereas P2 dissolved readily in these solvents. The glass‐transition temperature values were 128 °C for P1 and 37 °C for P2. The polymers emitted blue or violet‐blue light with photoluminescent maxima at about 445 and 460 nm for solutions and thin films, respectively. The bulky pendants reduced their tendency to form aggregates. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1091–1098, 2003
Polyester polyols: Synthesis and characterization of diethylene glycol terephthalate oligomers
Authors: Kadkin Oleg , Osajda Karol , Kaszynski Piotr , Barber Thomas A.
Published: March 2003

The composition of polyester polyols derived from terephthalic acid (TPA) and diethylene glycol (DEG) was examined. The synthesis of individual oligomers 1,n is described. The compounds were characterized with 1H and 13C NMR, mass spectrometry, and elemental analyses. The resonance signals arising from aromatic protons in 1,n = 1–3 were identified in 1H NMR spectra of TPA‐DEG condensates. From 1H NMR studies and chromatographic separation, it was concluded that the condensation of TPA and DEG in a 1:2 molar ratio results in a mixture of linear oligomers 1 with the average ñ varying from 1.1 to 2.2, and containing about 2% of cyclic oligomer 2. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1114–1123, 2003