bluuebunny/crossref_metadata_2025 huggingface dataset:
Empirical force fields for biological macromolecules: Overview and issues
Authors: Mackerell Alexander D.
Published: July 2004

Empirical force field‐based studies of biological macromolecules are becoming a common tool for investigating their structure–activity relationships at an atomic level of detail. Such studies facilitate interpretation of experimental data and allow for information not readily accessible to experimental methods to be obtained. A large part of the success of empirical force field‐based methods is the quality of the force fields combined with the algorithmic advances that allow for more accurate reproduction of experimental observables. Presented is an overview of the issues associated with the development and application of empirical force fields to biomolecular systems. This is followed by a summary of the force fields commonly applied to the different classes of biomolecules; proteins, nucleic acids, lipids, and carbohydrates. In addition, issues associated with computational studies on “heterogeneous” biomolecular systems and the transferability of force fields to a wide range of organic molecules of pharmacological interest are discussed. © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 1584–1604, 2004
Role of HER receptors family in development and differentiation
Authors: Casalini Patrizia , Iorio Marilena V. , Galmozzi Enrico , Ménard Sylvie
Published: July 2004

Members of the epidermal growth factor receptor family of receptor tyrosine kinases play a critical role in both development and oncogenesis. The latter is suggested by the frequent overexpression of HER‐2, EGFR, and HER‐3 in some human carcinomas, primarily breast and squamous cancer. The biological activities of the EGFR family are exerted through various ligand–receptor and receptor–receptor interactions. One receptor that plays a central role in this signaling network is HER‐2/Neu, which is considered the preferred heterodimerization partner for other members of the EGFR family. The role of these receptors and their ligands in development is discussed, with particular emphasis on their ability to mediate a variety of pathways and cellular responses, including proliferation, differentiation, and apoptosis. © 2004 Wiley‐Liss, Inc.
Effects of Helicobacter pylori infection on cell cycle progression and the expression of cell cycle regulatory proteins
Authors: De Luca Antonio , De Falco Maria , Iaquinto Salvatore , Iaquinto Gaetano
Published: July 2004

Helicobacter pylori lives in the stomach lumen adhering and specifically interacting with gastric epithelial cells. H. pylori infection can cause a broad range of diseases. Although most infected individuals only develop a chronic inflammation of the stomach, some patients progress to chronic gastritis, duodenal ulceration, or, rarely, cancer. H. pylori is able to send and to receive signals from the gastric epithelium, allowing host and bacteria to become linked in a dynamic equilibrium. Several studies have demonstrated that H. pylori infection induces morphological changes of gastric epithelial cells other than cell proliferation, increase of mitosis and mutations. It has also been demonstrated that H. pylori may predispose to cancer by altering gastric epithelial cell turnover acting specifically on transcription factors. Although H. pylori is able to induce several host responses, it specifically perturbs the delicate balance of those factors that usually help to maintain cell homeostasis. The study of mechanisms of interaction between the bacterium and gastric cells will surely help to prevent the increase and diffusion of malignancies all over the world. © 2004 Wiley‐Liss, Inc.
Membrane potential and endocytic activity control disintegration of cell–cell adhesion and cell fusion in vinculin‐injected MDBK cells
Authors: Palovuori Riitta , Myrsky Essi , Eskelinen Sinikka
Published: July 2004

Cell fusion occurs during fertilization and in the formation of organs such as muscles, placenta, and bones. We have developed an experimental model for epithelial cell fusion which permits analysis of the processes during junction disintegration and formation of polykaryons (Palovuori and Eskelinen [2000] Eur. J. Cell. Biol. 79: 961–974). In the present work, we analyzed the process in detail. Cell fusion was achieved by microinjecting into the cytoplasm of kidney epithelial Madin‐Darby bovine kidney (MDBK) cells TAMRA‐tagged vinculin, which incorporated into lateral membranes, focal adhesions and nucleus, and, prior fusion, induced internalization of actin, cadherin and plakoglobin to small clusters in cytoplasm. Injected vinculin was still visible at lateral membranes after removal of junctional proteins indicating that it was tightly associated and perturbed the cell–cell contact sites resulting in membrane fragmentation. Injection of active Rac together with vinculin induced accumulation of cadherin to the membranes, but did not affect vinculin–membrane association. However, it hampered cell fusion probably by supporting adherens junctions. In order to stop endocytosis, we lowered intracellular pH of vinculin‐injected cells to 5.5 with the aid of nigericin in KCl buffer. In acidified cells, injected vinculin delineated lateral membranes as thick layers, cadherin remained in situ, and cell fusion was completely inhibited. Since this treatment also leads to cell depolarization, we checked the vinculin incorporation in a KCl solution containing nigericin at neutral pH. In these circumstances, both endogenous and injected vinculin delineated lateral membranes as very thin discontinuous layers, but still fusion was hampered most likely due to perturbation in the initial vinculin–membrane association. We suggest that vinculin might function as a sensor of the environment triggering cell fusion during development in circumstances where membrane potential and local and transient pH gradients play a role. © 2004 Wiley‐Liss, Inc.
Influence of the extracellular matrix on the regulation of cardiac fibroblast behavior by mechanical stretch
Authors: Atance Joel , Yost Michael J. , Carver Wayne
Published: July 2004

Fibroblasts are responsible in large part for production, organization, and turnover of the extracellular matrix (ECM), thereby regulating the fibrotic content of the heart. Excessive fibrosis, which has been associated with certain forms of hemodynamic overload such as hypertension, is thought to result in increased ventricular chamber stiffness, and eventual heart failure. As such, the role of mechanical stretch in regulating fibroblast activity is crucial to our understanding of healthy and diseased hearts. However, little is known about the effects of alterations in the composition of the ECM in regulating mechanotransduction in cardiac fibroblasts. In order to address this question, rat cardiac fibroblasts were cultured on silastic membranes coated with different ECM substrates, and cyclically stretched for various durations. Experiments were designed to assess the activation of signaling pathways, as well as changes in collagen production, cellular proliferation, and morphology. Mitogen activated protein kinase (MAP kinase) was most rapidly activated, and collagen I expression was most abundant, in cells stretched on randomly organized collagen, and uncoated charged membranes. Regardless of the nature of the ECM substrate, stretched cells decreased proliferation, however, this effect was most marked in cells stretched on randomly organized collagen. Finally, cells stretched on all ECM substrates increased their surface area, but this was observed most significantly in cells adherent to aligned collagen, randomly organized collagen, and uncoated, charged membranes. Taken together, these results suggest cardiac fibroblasts may differentially interpret a mechanical stimulus, in terms of both signal transduction, and specific long‐term events such as gene transcription, based on the composition and organization of the ECM. © 2004 Wiley‐Liss, Inc.
Embryonic mouse testis development: Role of platelet derived growth factor (PDGF‐BB)
Authors: Ricci G. , Catizone A. , Galdieri M.
Published: July 2004

Platelet‐derived growth factors (PDGFs) are paracrine growth factors mediating epithelial–mesenchymal interactions and exerting multiple biological activities which include cell proliferation, motility, and differentiation. As previously demonstrated, PDGFs act during embryonic development and recently, by culturing male genital ridges, we have demonstrated that PDGF‐BB is able to support in vitro testicular cord formation. In the present paper, we report that PDGF‐BB is present during embryonic testis development and, in organ culture, induces cord formation although with reduced diameters compared with the cords formed in the genital ridges cultured in the presence of HGF. Moreover we have analyzed the roles exerted by this growth factor during the morphogenesis of the testis. We demonstrate by immunohistochemical experiments that PDGF‐BB and its receptors are synthesized by the male UGRs isolated from 11.5 and 13.5 dpc embryos and by Western blot that the factor is secreted in a biologically active form by testicular cells isolated from 13.5 dpc embryos. The biological roles of the factor have also been studied and we demonstrate that PDGF‐BB acts as a migratory factor for male mesonephric cells whose migration is a male specific event necessary for a normal testicular morphogenesis. In addition we demonstrate that during testicular development, PDGF‐BB induces testicular cell proliferation being in this way responsible for the increase in size of the testis. Finally we demonstrate that PDGF‐BB is able to reorganize dissociated testicular cells inducing the formation of large cellular aggregates. However the structures formed in vitro under PDGF‐BB stimulation never had a cord‐like morphology similar to the cord‐like structures formed in the presence of HGF (Ricci et al., 2002, Mech Dev 118:19–28), suggesting that this factor does not act as a morphogenetic factor during testicular development. All together the data presented in this paper demonstrate that PDGF‐BB and its receptors (α‐ and β‐subunits) are present during the crucial ages of embryonic mouse testis morphogenesis and indicate the multiple roles exerted by this factor during the development of the male gonad. © 2004 Wiley‐Liss, Inc.
Molecular identification of ERα‐positive breast cancer cells by the expression profile of an intrinsic set of estrogen regulated genes
Authors: Weisz Alessandro , Basile Walter , Scafoglio Claudio , Altucci Lucia , Bresciani Francesco , Facchiano Angelo , Sismondi Piero , Cicatiello Luigi , De Bortoli Michele
Published: July 2004

Estrogens exert a key biological role in mammary gland epithelial cells and promote breast carcinogenesis and tumor progression. We recently identified a new large set of estrogen responsive genes from breast cancer (BC) cells by DNA microarray analysis of the gene expression profiles induced by 17β‐estradiol in ZR‐75.1 and MCF‐7 cells. The purpose of the present study was to test whether the expression pattern of hormone regulated genes from this set identifies estrogen receptor (ERα) positive, hormone responsive BC cells. To this aim, we carried out in silico metanalysis of ERα positive and ERα negative human BC cell line transcriptomes, focusing on two sets of 171 and 218 estrogen responsive genes, respectively. Results show that estrogen dependent gene activity in hormone responsive BC cells is significantly different from that of non‐responsive cells and, alone, allows to discriminate these two cellular phenotypes. Indeed, we have identified 61 genes whose expression profile specifically marks ERα positive BC cells, suggesting that this gene set may be exploited for phenotypic characterization of breast tumors. This possibility was tested with data obtained by gene expression profiling of BC surgical samples, where the ERα positive phenotypes were highlighted by the expression profile of a subset of 27 such hormone responsive genes and four additional BC marker genes, not including ERs. These results provide direct evidence that the expression pattern of a limited number of estrogen responsive genes can be exploited to assess the estrogen signaling status of BC cells both in vitro and ex‐vivo. © 2004 Wiley‐Liss, Inc.
MyoD induces the expression of p57Kip2 in cells lacking p21Cip1/Waf1: Overlapping and distinct functions of the two cdk inhibitors
Authors: Figliola Rocco , Maione Rossella
Published: July 2004

The myogenic factor MyoD induces the expression of the cdk inhibitor p21 to promote cell cycle withdrawal in differentiating myoblasts. Although the cdk inhibitor p57 is also highly expressed in skeletal muscle and is thought to redundantly control myogenesis, little is known about its regulation, that has been suggested to be independent of MyoD. Here we show, for the first time, that MyoD is capable to induce the expression of p57. Intriguingly, this ability is restricted to cells lacking p21, suggesting that the two cdk inhibitors may be expressed in different muscle cell lineages. We also suggest that the functions of p21 and p57 in myoblast cells are only in part redundant. In fact, while the two cdk inhibitors play a similar role in cells undergoing G1 arrest during MyoD‐induced differentiation, p57 does not replace p21 in cells escaping G1 arrest and undergoing MyoD‐induced apoptosis. This difference can be ascribed both to a different subcellular localization and to a differential ability of the two cdk inhibitors to interact with cell cycle regulators. © 2004 Wiley‐Liss, Inc.
In vivo transfection of the mouse vas deferens
Authors: Valenzuela Mario , Relloso Miguel , Esponda Pedro
Published: June 2004

To explore the possibility that specific characteristics of the epithelium of the male tract can be modified, transfections of the mouse vas deferens have been performed using in vivo injections of cationic DNA/liposome complexes. Gene transfer was done employing the reporter genes pEGFP‐C1 encoding Green Fluorescent Protein (GFP) and pCMV‐nls‐β encoding the nuclear β‐Galactosidase (β‐Gal). Foreign gene expression reached a maximum of 6.8% in the epithelial cells of the vas after treatment with the nuclear β‐Gal gene construction and of 13.3% after employing the GFP gene construction. Expression of the GFP gene appeared from one week up to three months following injection, and it appeared as patches of modified cells along the epithelium. Results from immunocytochemistry and Western Blotting support the conclusion that transfection of epithelial cells was achieved. We have also transfected the vas using gene constructions that express secretory proteins— specifically, the reporter system pSEAP‐control that expresses a secretory form of human placental alkaline phosphatase, and the pGFP‐Ctk‐37 that expresses a secretion form of GFP. In both cases, the fluids expressed from the transfected vas showed a significant increase of alkaline phosphatase activity after pSEAP transfection and the presence of GFP protein when pGFP‐Ctk‐37 gene construction was employed. Our results indicate that the vas can be transfected in vivo using liposomes as vectors of foreign genes and that the vas fluid contents can be modified. J. Exp. Zool. 293:532–540, 2002. © 2002 Wiley‐Liss, Inc.
‘Doing development’: the gap year, volunteer‐tourists and a popular practice of development
Authors: Simpson Kate
Published: July 2004

Over the last ten years the gap year has become a popular and publicly recognized phenomenon. One of the most visible forms of this phenomenon has been the emergence of ‘third world’ volunteer‐tourism programmes, which seek to combine the hedonism of tourism with the altruism of development work. Such programmes make the practice of international development doable, knowable and accessible to young travellers. This paper seeks to critique the construction of this public face of development, while also asking, from a pedagogical perspective, what travelling participants learn about ‘the others’ they encounter on, and through, such programmes. Copyright © 2004 John Wiley & Sons, Ltd.
Contradiction and change? NGOs, schools and the public faces of development
Authors: Smith Matt
Published: July 2004

This paper addresses the contradictions that increasingly shape the public faces of development. Focusing on examples of the communication of development by International Non‐Governmental Organizations and UK schools, emphasis is placed on the social, political, economic and cultural dynamics that inform the public faces of development, and the tensions and dilemmas that these produce. The paper also highlights the need to look beyond the formal institutions and machineries of development to understand the contemporary production of development's public faces. Copyright © 2004 John Wiley & Sons, Ltd.
Distinguishing N‐oxide and hydroxyl compounds: impact of heated capillary/heated ion transfer tube in inducing atmospheric pressure ionization source decompositions
Authors: Peiris Dilrukshi M. , Lam Wing , Michael Steven , Ramanathan Ragu
Published: June 2004

In the pharmaceutical industry, a higher attrition rate during the drug discovery process means a lower drug failure rate in the later stages. This translates into shorter drug development time and reduced cost for bringing a drug to market. Over the past few years, analytical strategies based on liquid chromatography/mass spectrometry (LC/MS) have gone through revolutionary changes and presently accommodate most of the needs of the pharmaceutical industry. Among these LC/MS techniques, collision induced dissociation (CID) or tandem mass spectrometry (MS/MS and MSn) techniques have been widely used to identify unknown compounds and characterize metabolites. MS/MS methods are generally ineffective for distinguishing isomeric compounds such as metabolites involving oxygenation of carbon or nitrogen atoms. Most recently, atmospheric pressure ionization (API) source decomposition methods have been shown to aid in the mass spectral distinction of isomeric oxygenated (N‐oxide vs hydroxyl) products/metabolites. In previous studies, experiments were conducted using mass spectrometers equipped with a heated capillary interface between the mass analyzer and the ionization source. In the present study, we investigated the impact of the length of a heated capillary or heated ion transfer tube (a newer version of the heated capillary designed for accommodating orthogonal API source design) in inducing for‐API source deoxygenation that allows the distinction of N‐oxide from hydroxyl compounds. 8‐Hydroxyquinoline (HO‐Q), quinoline‐N‐oxide (Q‐NO) and 8‐hydroxyquinoline‐N‐oxide (HO‐Q‐NO) were used as model compounds on three different mass spectrometers (LCQ Deca, LCQ Advantage and TSQ Quantum). Irrespective of heated capillary or ion transfer tube length, N‐oxides from this class of compounds underwent predominantly deoxygenation decomposition under atmospheric pressure chemical ionization conditions and the abundance of the diagnostic [M + H − O]+ ions increased with increasing vaporizer temperature. Furthermore, the results suggest that in API source decompostion methods described in this paper can be conducted using mass spectrometers with non‐heated capillary or ion transfer tube API interfaces. Because N‐oxides can undergo in‐source decomposition and interfere with quantitation experiments, particular attention should be paid when developing API based bioanalytical methods. Copyright © 2004 John Wiley & Sons, Ltd.
Structure, reactivity and thermochemical properties of protonated lactic acid
Authors: Berruyer‐Penaud Florence , Bouchoux Guy , Payen Olivier , Sablier Michel
Published: June 2004

The protonation energetics of lactic acid (LA) were experimentally determined by the kinetic method including the entropy effect. The values (proton affinity, PA(LA) = 817.4 ± 4.3 kJ mol−1; protonation entropy, ΔS°p(LA) = −2 ± 5 J K−1 mol−1; gas‐phase basicity, GB(LA) = 784.5 ± 4.5 kJ mol−1) agree satisfactorily with computed G2(MP2) expectations (PA(LA) = 811.8 kJ mol−1; ΔS°p(LA) = −7.1 J K−1 mol−1; GB(LA) = 777.4 kJ mol−1). The fragmentation behaviour of protonated lactic acid (LAH+) is dominated by carbon monoxide loss followed by elimination of a water molecule. Direct dehydration of LAH+ is only a high‐energy process hardly competitive with the CO loss. A complete mechanistic scheme, based on MP2/6–31G* calculations, is proposed; it involves isomerization of the various protonated forms of LA and the passage through the ion–neutral complex between the 2‐hydroxypropyl acylium cation and a water molecule. Copyright © 2004 John Wiley & Sons, Ltd.
Temporal profile of ultrastructural changes in cortical neurons after a photochemical lesion
Authors: Andersson Benita , Wu Xingchen , Bjelke Börje , Syková Eva
Published: July 2004

A photochemical lesion was induced in the right sensory motor cortex of rat brains. We examined at various time points the occurrence of different types of neuronal death with respect to a potential therapeutic window. The lesion appearance was documented by magnetic resonance imaging, and functional recovery was evaluated by behavioral tests showing recovery at 48 hr after lesioning. At 0.5, 1, 3, 6, 12, 24, 48, and 72 hr postlesion, cortical layers IV and V were examined by light and electron microscopy. Ultrastructural changes, which corresponded well to light microscopy findings, were found in both hemispheres. In the lesioned area, the neuropil appeared disorganized at 0.5 hr, and apoptotic and necrotic cell death was found at 0.5–3 hr. After 3 hr, the tissue was disintegrated. On the contralateral side, chromatin clumping appeared at 0.5–3 hr. At 3 hr, ruptured membranes were found, a sign of irreversible cell death. At 6–72 hr, the membranes were intact, and the chromatin was not clumped but heterogeneously distributed. The nuclei contained dispersed nucleoli at 48–72 hr. The morphology correlated well with magnetic resonance images and functional behavior. Our study demonstrates that a photochemical lesion is a useful model for studying morphological changes in injured cells. It results in a permanent infarction within 3 hr. In that the morphology on the contralateral side drastically changed between 3 and 6 hr, the cellular alterations at these time points might represent a break point at which cells either progress toward cell death or recover. © 2004 Wiley‐Liss, Inc.
Thermo‐Physical and Impact Properties of Epoxy Containing Epoxidized Linseed Oil, 2
Authors: Miyagawa Hiroaki , Mohanty Amar K. , Misra Manjusri , Drzal Lawrence T.
Published: July 2004

Summary: Biobased neat epoxy materials containing epoxidized linseed oil (ELO) were processed with an amine curing agent. A defined amount of diglycidyl ether of bisphenol F (DGEBF) was replaced by ELO. The thermophysical properties of the amine‐cured biobased neat epoxy were measured by dynamic mechanical analysis (DMA). The Izod impact strength increased with an increase in the amount of ELO added. The change in the Izod impact strength was correlated with the thermophysical properties measured by DMA.

Relation between the Izod impact strength and loss factor for amine‐ and anhydride‐cured ELO‐containing epoxy resins.

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Relation between the Izod impact strength and loss factor for amine‐ and anhydride‐cured ELO‐containing epoxy resins.
Thermo‐Physical and Impact Properties of Epoxy Containing Epoxidized Linseed Oil, 1
Authors: Miyagawa Hiroaki , Mohanty Amar K. , Misra Manjusri , Drzal Lawrence T.
Published: July 2004

Summary: Biobased neat epoxy materials containing epoxidized linseed oil (ELO) were processed with an anhydride curing agent. A defined amount of the diglycidyl ether of bisphenol F (DGEBF) was replaced by ELO. The selection of the DGEBF, ELO, and an anhydride curing agent resulted in an excellent combination, to provide a new biobased epoxy material showing high elastic modulus, high glass transition temperature, and high heat distortion temperature (HDT) with larger amounts of ELO. The Izod impact strength was almost constant while changing the amount of ELO. This is a promising result for future industrial applications in different engineering industries.

The effect of changing ELO concentration of the anhydride‐cured neat epoxy on the storage modulus.

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The effect of changing ELO concentration of the anhydride‐cured neat epoxy on the storage modulus.
Bioconjugation of (CdSe)ZnS Quantum Dots Using a Genetically Engineered Multiple Polyhistidine Tagged Cohesin/Dockerin Protein Polymer
Authors: Ding Shi‐You , Rumbles Garry , Jones Marcus , Tucker Melvin P. , Nedeljkovic Jovan , Simon Martha N. , Wall Joseph S. , Himmel Michael E.
Published: July 2004

Summary: We have constructed bioconjugates consisting of genetically modified cohesin/dockerin protein polymers combined with (CdSe)ZnS colloidal quantum dots. This recombinant protein contains fusions of Clostridium thermocellum cellulosomal cohesin and dockerin domains and a C‐terminal 6×‐histidine tag. These unique cohesin/dockerin monomeric building blocks (ca. 60 kDa) were allowed to self‐assemble, yielding oligomers and polymers, which were subsequently characterized by high‐pressure size exclusion chromatography (HPSEC). The C‐terminal 6×‐His tags from each monomer facilitate binding to the quantum dot surface chemistry while mix the protein polymers with water‐soluble QDs at neutral pH. Using HPSEC, we were able to fractionate the reaction mixture into two major distributions of bioconjugate species. Scanning transmission electron microscopy (STEM) and photoluminescence spectroscopy (PL) were employed to characterize the components from these chromatographic fractions. The fraction containing the larger bioconjugates contained clusters of quantum dots surrounded by protein polymers with an estimated radius of 190 ± 30 Å and an apparent molecular weight of 8 000 ± 3 000 kDa. The STEM images from the fraction containing the smaller species were amenable to detailed analysis and graphical simulation that revealed species containing one, two, or three quantum dots surrounded by 10, 15, or 18 protein monomers, respectively. Our data demonstrate strong binding coefficients not only between the protein monomers to form polymers, but also with the (CdSe)ZnS colloidal quantum dots and thus provides a method of producing stable, water‐soluble luminescent quantum dot bioconjugates. PL spectroscopic analysis shows that the samples from both chromatographic fractions have strong excitonic emission with a peak at ca. 2.2 eV (562 nm).

STEM images of cohesin/dockerin protein polymer‐QD conjugates from the HPSEC elution peak. A represents a typical STEM image 512 × 512 nm scanning field showing the conjugates containing 1, 2, and 3 QDs with 10, 15, and 18 protein monomers surrounded, respectively.

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STEM images of cohesin/dockerin protein polymer‐QD conjugates from the HPSEC elution peak. A represents a typical STEM image 512 × 512 nm scanning field showing the conjugates containing 1, 2, and 3 QDs with 10, 15, and 18 protein monomers surrounded, respectively.
Relaxation of Copolymeric Dendrimers Built from Alternating Monomers
Authors: Satmarel Cristian , Gurtovenko Andrey A. , Blumen Alexander
Published: July 2004

Summary:In this study we extend our previous work concerning the Rouse dynamics of linear alternating copolymers (Macromolecules2003,36, 486) to tree‐like structures and focus on copolymeric dendrimers built from monomers of two kindsAandB; as before, we let the monomers differ in their interaction with the solvent. In the framework of generalized Gaussian structures (GGS), we consider alternating arrangements of monomers over the dendritic structures. We develop a semi‐analytical method to determine for such structures (of arbitrary functionality,f, and number of generations,g), the eigenfrequencies (relaxation times). The method allows us to compute readily the storage, [G′(ω)] and the loss, [G″(ω)] moduli. These quantities show a multitude of features which mainly depend on the difference in the mobilities, or, equivalently, in the friction coefficientsζAandζBof theA‐ andB‐beads. These features range from the presence of large plateau‐type regions in [G′(ω)] to the appearance of double‐peaks in [G″(ω)]. In contrast to linear alternating copolymers, the behavior of the dynamic moduli of copolymeric systems with dendritic topology can shed light into their composition, i.e. into the relative numbers ofA‐ andB‐beads. We discuss these aspects in view of their experimental relevance.

A system under study: a dendrimer of third generation (g = 3) with functionalityf = 3, composed of alternating beads.

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A system under study: a dendrimer of third generation (g = 3) with functionalityf = 3, composed of alternating beads.
Biocoating of Electropolished and Ultra‐Hydrophilic Titanium and Cobalt Chromium Molybdenum Alloy Surfaces with Proteins
Authors: Chatzinikolaidou M. , Laub M. , Rumpf H. , Jennissen H. P.
Published: June 2004

Bone morphogenetic proteins (BMPs) play a decisive role in bone development and osteogenesis. In the past they have been the subject of widespread research and clinical trials as stimulants of bone growth. Although recently recombinant human BMP‐2 (rhBMP‐2) has been chemically immobilized on implant surfaces leading to enhanced bone growth and accelerated integration in vivo, the non‐covalent immobilization of proteins on metal surfaces is still poorly understood, since the oxide layers on metals like titanium, stainless steel or cobalt chromium alloys are poor adsorbents of proteins. Protein binding surfaces could either be generated by linking ionic groups (ion‐exchange surface) or by coupling hydrophobic residues (hydrophobic interacting surface, HIS) to the surface. In this paper the preparation of protein adsorbing surfaces on titanium and cobalt chromium molybdenum alloy for the adsorption of rhBMP‐2 and ubiquitin will be described. rhBMP‐2 and ubiquitin are bound extremely tight to surfaces containing propyl or hexyl groups of a certain surface concentration and are slowly released over a range of at least 24–100 days making such surfaces applicable as long‐term drug delivery devices for enhancing bone growth or implant integration.
Contact allergies to metal components of the 316 L steel in patients with coronary heart disease
Authors: Hillen U. , Haude M. , Erbel R. , Goos M.
Published: June 2004

In‐stent restenosis is a complication which impairs the success of coronary stenting. Recently it was supposed that a delayed hypersensitivity reaction to nickel and molybdenum might be one of the triggering factors in in‐stent restenosis. We have performed a retrospective analysis of the data collected in our centre with respect to this hypothesis. Altogether 20 patients were investigated (13 male, 7 female). Patch tests were performed with the standard series of the German Contact Dermatitis Research Group and a metal series containing the metal components of the 316 L stainless steel. A positive patch test reaction to nickel was observed in 2 (10.0%) patients, one of these patients had an in‐stent restenosis, the other had not. None of the patients showed a sensitization to the other metals. Restenoses were predominantly observed in patients with a negative patch test reaction to nickel (6/18 patients). Although it cannot be excluded that metal allergy may play a role in the restenosis process in coronary stenting there is at the moment little evidence for it.
Enhancement of waveguide model for propagation‐loss prediction in tunnels
Authors: Zhang Y. P.
Published: June 2004

For microcellular system design, we have enhanced a well‐known waveguide model for propagation‐loss prediction along an LOS propagation path in a tunnel. It is reported in this letter. The enhancement involves a more accurate calculation of the tilt loss, the distinction of the two propagation regions, and the suggestion of using the free‐space model for one region and the waveguide model for the other. The enhancement is demonstrated with examples. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 10–12, 2001.
Quasi‐TEM analysis of a novel coplanar waveguide and coupled structure
Authors: Zhou Xilang , Chen Jinghua , Chen Zhongqiang
Published: June 2004

A novel coplanar waveguide (CPW) and coupled structure with a cylindrical conductor as the shielding are proposed. Simple analytic formulas for the capacitance per unit length and characteristic impedance of the structure are derived using the conformal mapping technique. The numerical results are in good agreement with those obtained by other authors. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 49–51, 2001.
Uniplanar four‐element Vivaldi array fed by a coplanar waveguide
Authors: Linardou I. , Migliaccio C.
Published: June 2004

This letter describes the design of a uniplanar parallel‐series‐fed linear array of Vivaldi antennas. Matching conditions have been optimized with an equivalent‐circuit model. The array exhibits 12dBi gain in the substrate plane, 80% radiation efficiency, and low cross polarization over 5% bandwidth centered at 4.2GHz. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 60–62, 2001.
Relationship between thermally induced lensing and output power for a high‐power laser‐diode side‐pumped solid‐state laser
Authors: Yu Deli , Tang D. Y.
Published: July 2004

The variable focal length of thermal lensing in grains of a thermally loaded Nd:YAG crystal rod have been calculated and compared with the measurements of our system. By use of the space‐dependent rate equations, the analytical expression of the output power on the pump power, which consists of the factors of threshold volume and the focal length of thermal lensing, is presented. We investigate the threshold pump power, and the relationships between the output power and the pumping power under different lengths of thermal lensing. Experimental results concerning the output power of fundamental mode and the pump power, which are related to the thermal lensing and agreeable to the theoretical analysis are given. Finally, the optimized experimental output power of our laser system is obtained. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 361–365, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20305
Full‐wave analysis of industrial microwave applicators: TM modes
Authors: Lohr C. , Pribetich P. , Stuerga D.
Published: July 2004

A full‐wave analysis of TM modes (dispersion characteristics and field configurations) is presented for industrial devices able to heat pipes filled with lossy fluids such as water. These results are obtained by a numerical simulation based on the residue theory. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 365–369, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20306
EBG at microwave frequency range: Bragg and/or resonant effect?
Authors: Ibáñez Loinaz Asier , del Río Bocio Carlos
Published: July 2004

A rigorous consideration of the filtering effect of EBG structures at the microwave‐frequency range will be performed in this paper. We will show that, in this frequency range, the periodic‐structure filtering (or Bragg effect) and the self‐resonance of the different cells involved are tuned approximately at the same frequencies; thus, their influences are mixed in the final filter response. Both effects are defined by different geometrical laws and this is probably the main reason not to use a standard design method for a given filter requirement when using these technologies. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 383–385, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20311
Parabolic‐equation‐based study of ducting effects on microwave propagation
Authors: Sirkova I. , Mikhalev M.
Published: July 2004

This work reports a quantitative assessment of propagation losses for the frequency band 2110–2170 MHz under evaporation and surface‐based ducts conditions. Flat‐underlying‐surface and elevated‐terrain cases are studied. The calculations are based on the parabolic approximation to the wave equation in conjunction with finite‐element and Fourier split‐step techniques. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 390–394, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20314
Enhanced fractal microstrip‐antenna performance by using photonic‐bandgap fractal ground plane
Authors: Siakavara K.
Published: July 2004

In this paper, a Van Koch printed antenna on a photonic‐bandgap fractal substrate is presented. The substrate is designed with grounded Van Koch printed elements. The structure is a multifrequency radiator as a common fractal antenna, but the special synthesis of the substrate enhances the frequency bandwidth and gain, and drives the antenna to radiate a circularly polarized field. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 397–402, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20316
Continuous dynamics for a linear coupled‐oscillator array with peripheral coupling‐phase adjustments
Authors: Yoon Jung Ho , Myung Noh‐Hoon
Published: July 2004

A continuum model of the dynamics for a coupled‐oscillator array that presents an intuitive insight into the behavior of the frequency‐tuned array was introduced recently. In this paper, we further develop the continuous dynamics for the coupled‐oscillator array with a coupling‐phase adjustment of the coupling circuit at the peripheries of the array. The adjustment is verified by related experimental measurements. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 422–425, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20324
Bifrequency behaviour and bandwidth enhancement of a dielectric resonator antenna
Authors: Nannini C. , Ribero J. M. , Dauvignac J. Y. , Pichot Ch.
Published: July 2004

In this paper, we present a new configuration which enhances the impedance bandwidth (we obtain an increase of 80%) and exhibits dual‐frequency operation. The characteristics of the new structure are measured and discussed. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 432–434, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20327
Shear band evolution and accumulated microstructural development in Cosserat media
Authors: Tordesillas A. , Peters J. F. , Gardiner B. S.
Published: July 2004

This paper prepares the ground for the continuum analysis of shear band evolution using a Cosserat/micropolar constitutive equation derived from micromechanical considerations. The nature of the constitutive response offers two key advantages over other existing models. Firstly, its non‐local character obviates the mathematical difficulties of traditional analyses, and facilitates an investigation of the shear band evolution (i.e. the regime beyond the onset of localization). Secondly, the constitutive model parameters are physical properties of particles and their interactions (e.g. particle stiffness coefficients, coefficients of inter‐particle rolling friction and sliding friction), as opposed to poorly understood fitting parameters. In this regard, the model is based on the same material properties used as model inputs to a discrete element (DEM) analysis, therefore, the micromechanics approach provides the vehicle for incorporating results not only from physical experiments but also from DEM simulations. Although the capabilities of such constitutive models are still limited, much can be discerned from their general rate form. In this paper, an attempt is made to distinguish between those aspects of the continuum theory of localization that are independent of the constitutive model, and those that require significant advances in the understanding of micromechanics. Copyright © 2004 John Wiley & Sons, Ltd.
Steady infiltration from buried point source into heterogeneous cross‐anisotropic unsaturated soil
Authors: Chen G. J. , Gallipoli D.
Published: July 2004

The paper presents the analytical solution for the steady‐state infiltration from a buried point source into two types of heterogeneous cross‐anisotropic unsaturated half‐spaces. In the first case, the heterogeneity of the soil is modelled by an exponential relationship between the hydraulic conductivity and the soil depth. In the second case, the heterogeneous soil is represented by a multilayered half‐space where each layer is homogeneous. The hydraulic conductivity varies exponentially with moisture potential and this leads to the linearization of the Richards equation governing unsaturated flow. The analytical solution is obtained by using the Hankel integral transform. For the multilayered case, the combination of a special forward and backward transfer matrix techniques makes the numerical evaluation of the solution very accurate and efficient. The correctness of both formulations is validated by comparison with alternative solutions for two different cases. The results from typical cases are presented to illustrate the influence on the flow field of the cross‐anisotropic hydraulic conductivity, the soil heterogeneity and the depth of the source. Copyright © 2004 John Wiley & Sons, Ltd.
Political Reform and the Future of American Democracy
Authors: Bradley Bill , Gates Christopher T.
Published: July 2004

We live in a rapidly changing world, yet our political systems and structures seem painfully out of date. The role of money continues to raise questions about the fairness of electoral politics, much as it did at the dawn of the Progressive Era, one hundred years ago. Low voter turnouts reflect a growing sense of frustration with the political system, while new technologies and ideas for reform offer intriguing possibilities for the future. As we enter the twenty‐first century, what better time is there to explore these and other issues?
Elections and Civic Education: The Case of Kids Voting USA
Authors: Hall John Stuart , Jones Patricia M.
Published: July 2004

An innovative civic education project in Phoenix addresses citizen apathy and improves voter participation by developing the habit of responsible citizenship—and voting—in children. Unexpectedly, the program has also increased voter turnout among adults.
Filling the Governance Gap
Authors: Wallis Allan D.
Published: July 2004

Cities Without Suburbs
, by David Rusk

Metropolitics
, by Myron Orfield

Regional Politics
, edited by H. V. Savitch and Ronald K. Vogel

Regional Excellence
, by William R. Dodge

New Visions for Metropolitan America
, by Anthony Downs
A Civil Education for the Twenty‐First Century: Preparing Students for a Three‐Sector Society
Authors: Rifkin Jeremy
Published: July 2004

New economic and political realities require us to rethink the mission
of civic society in years to come. Thinking of society as creating three
types of capital—market, public, and social—opens up new possibilities for reconceptualizing the social contract and the kind of education
we give our young people.
A Dialogue on Healthy Communities: Past, Present, and Future
Authors: Duhl Leonard J. , Hancock Trevor , Twiss Joan
Published: July 2004

A conversation with three healthy‐cities, healthy‐communities pioneers.
Smoke‐Free California: Democracy Meets Public Health
Authors: Adams Christopher Freeman
Published: July 2004

An initiative of the California Healthy Cities Project (a statewide program to help cities and their local partners promote healthier communities), California Smoke‐Free Cities is an example of an effort that is grounded in such healthy‐cities principles as inclusiveness, cooperation, and building on current assets.
Doing Democracy: An Exploration of Progressive‐Era Reform and Its Legacy for American Politics
Authors: Mattson Kevin
Published: July 2004

The social centers movement of the early twentieth century tried to show exactly what democratic politics could look like by opening public schools as places where adult citizens could educate themselves and one another about current political issues. At these evening “social centers,” citizens could learn about issues, deliberate with one another, and make decisions among possibilities for action.
Fifty Years of Civic Accomplishment: The History of the All‐America City Award
Authors: McGrath Michael
Published: June 2004

Looking back at the award‐winning projects of All‐America Cities reveals how these communities have addressed the most pressing issues of their times.
Public Participation in Local Government: Points of View
Authors: Lando Tom
Published: June 2004

American government is supposed to be “by the people and for the people.” Too often, however, public decision‐making processes fail to meet that lofty standard. How can communities change so that citizens have a more significant role in forming the policies that will govern their futures?
Public Hospital Authorities for Public Purposes?
Authors: O'Looney John
Published: June 2004

It is estimated that there are more than seven thousand independent public authorities in the United States. What makes these quasi‐
governmental authorities unique is a blend of public powers with a more private‐sector‐like administrative style. By being able to avoid the formal rules that permeate most public bureaucracies, they can move more swiftly and decisively than government, but at the potential risk of special interests having substantially greater influence over public policy decisions than the public at large.
Creating a Healthy Democracy
Authors: Gates Christopher T.
Published: June 2004

It has never been more difficult for local governments to meet the challenges they face. The issues have grown increasingly complex. Angry citizens and cynical news media mock the political process and despair of finding solutions to community problems. The National Civic League, however, has come to recognize that issues do not stop communities—communities stop themselves. No challenge is too big or difficult when government, business, nonprofits, and citizens come together to work toward common goals. The Civic Index is a valuable tool for communities to use to evaluate where they stand within the new realities of citizen democracy and to determine their strengths and weaknesses.
Stages of the Process: Using the Civic Index
Authors: Okubo Derek , Weidman Karen , O'Connor Drew , Geha Nancy
Published: June 2004

The National Civic League provides a framework for optimal use of the Civic Index; however, the index can be adapted to fulfill the needs of specific communities, programs, and other entities. Each community must decide which approach is most appropriate to its particular needs. The Civic Index process typically has three stages: the initiating stage, the stakeholder stage, and the implementation stage. Understanding the stages of the process can help communities use the Civic Index to assess their own civic infrastructures.