bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heterocyclic amines: Chemistry and health
Authors: Cheng Ka‐Wing , Chen Feng , Wang Mingfu 
Published: November 2006

AbstractHeterocyclic amines (HAs) occur at the ppb range in foods. Most of them demonstrate potent mutagenicity in bacteria mutagenicity test, and some of them have been classified by the International Agency for Research on Cancer as probable/possible human carcinogens. Their capability of formation even during ordinary cooking practices implies frequent exposure by the general public. Over the past 30 years, numerous studies have been stimulated aiming to alleviate human health risk associated with HAs. These studies contribute to the understanding of their formation, characterization, and quantification in foods; their mutagenesis/carcinogenesis, mechanisms of antimutagenesis by chemical or phytogenic modulators; and strategies to inhibit their formation. The chemistry of HAs, their implications in human health, factors influencing their formation, and feasible ways of suppression will be briefly reviewed. Their occurrence in trace amounts in foods necessitates continuous development and amelioration of analytical techniques. Various inhibitory strategies, ranging from modifying cooking conditions to incorporation of different modulators, have been developed. This will remain one of the foremost areas of research in the field of food chemistry and safety.
Quantitative 19F MR spectroscopy at 3 T to detect heterogeneous capecitabine metabolism in human liver
Authors: Klomp Dennis , van Laarhoven Hanneke , Scheenen Tom , Kamm Yvonne , Heerschap Arend 
Published: November 2006

AbstractChemotherapy in non‐responding cancer patients leads to unnecessary toxicity. A marker is therefore required that can predict the sensitivity of a specific tumour to chemotherapy, which would enable individualisation of therapy. 19F MR spectroscopy (19F MRS) can be used to monitor the metabolism of fluorinated drugs. The aim of this study was to develop a method for quantified localised detection of fluorinated compounds in human liver. For this purpose, sensitivity‐optimised localised 19F MRS methods at 3 T were used to detect MR signals from capecitabine, 5′DFUR, 5′DFCR and FBAL after oral intake of capecitabine. As the radio‐frequency (rf) coil is made tuneable to 19F and 1H, the same localisation method is applied to obtain 1H MR signals of water and of the 19F metabolites. In addition, T1 measurements have been performed to correct for measurement‐induced saturation effects. Finally, absolute tissue concentrations of capecitabine metabolites were obtained in vivo, which revealed a substantial spatial heterogeneity of these metabolites in human liver after chemotherapy. Copyright © 2006 John Wiley & Sons, Ltd.
A study of the representation of cracks with level sets
Authors: Duflot Marc 
Published: November 2006

AbstractThe level set method has been used for a few years to represent cracks in fracture mechanics simulations instead of an explicit description of the cracks faces geometry. This paper studies in detail the shape of the level set functions around a crack in two dimensions that is propagating with a sharp kink, obtained both with level set update methods found in the literature and with several innovative update methods developed by the author. A criterion based on the computation of a J integral of a virtual displacement field obtained with the values of the level set functions is proposed in order to assess the quality of these update methods. With the help of this criterion, two optimal approaches are identified, which predict an accurate evolution of the crack with smooth and consistent level set functions. These methods are then applied in three dimensions to the case of an initially penny‐shaped crack that propagates out of its plane. Copyright © 2006 John Wiley & Sons, Ltd.
Hybrid numerical scheme for time‐evolving wave fields
Authors: Lilis G. N. , Halder A. , Telukunta S. , Servetto S. 
Published: November 2006

AbstractMany problems in geophysics, acoustics, elasticity theory, cancer treatment, food process control and electrodynamics involve study of wave field synthesis (WFS) in some form or another. In the present work, modelling of wave propagation phenomena is studied as a static problem, using finite element method and treating time as an additional spatial dimension. In particular, WFS problems are analysed using discrete methods. It is shown that a fully finite element‐based scheme is very natural and effective method for the solution of such problems.Distributed WFS in the context of two‐dimensional problems is outlined and incorporation of any geometric or material non‐linearities is shown to be straightforward. This has significant implications for problems in geophysics or biological media, where material inhomogeneities are quite prevalent. Numerical results are presented for several problems referring to media with material inhomogeneities and predefined absorption profiles. The method can be extended to three‐dimensional problems involving anisotropic media properties in a relatively straightforward manner. Copyright © 2006 John Wiley & Sons, Ltd.
Use of moving distributed mass element for the dynamic analysis of a flat plate undergoing a moving distributed load
Authors: Wu Jia‐Jang 
Published: November 2006

AbstractThis paper presents the theory regarding a moving distributed mass element, so that the dynamic responses of a rectangular plate subjected to a moving distributed mass, with the effects of inertia force, Coriolis force and centrifugal force considered, can be easily determined. In which, the property matrices of the moving distributed mass element are derived by means of the principle of superposition and the definition of shape functions, and the overall property matrices of the entire vibrating system are determined from the combination of the last element property matrices of the moving distributed mass element and those of the plate itself. Since the property matrices of the moving distributed mass element have something to do with the instantaneous position and the distribution of the moving mass, they are time‐dependent and so are the overall property matrices of the entire vibrating system. Based on the last concept, the equations of motion for a rectangular plate subjected to a moving distributed mass are established and solved to yield the dynamic responses of the entire vibrating system. Numerical results reveal that the factors such as the contact area (between the moving distributed mass and the plate), moving‐load speed, inertia force, Coriolis force and centrifugal force affect the vibration characteristics of the plate to some degree. Copyright © 2006 John Wiley & Sons, Ltd.
Creating effective customer relationships in not‐for‐profit retailing: the Ten Thousand Villages example
Authors: Dato‐on Mary Conway , Joyce Mary , Manolis Chris 
Published: November 2006

Abstract

This paper examines Ten Thousand Villages (a not‐for‐profit organization with retail operations in US and Canada that pays Third World artisans fair market value for their works) in terms of its retailing and customer relationship management (CRM) strategies. The authors present an analysis of one Ten Thousand Villages retail store to assess if and how CRM might be successfully implemented. The analysis considers the use of a volunteer retail sales force and how volunteers might successfully interface with customers.

Copyright © 2006 John Wiley & Sons, Ltd.
The effect of management commitment to service quality on frontline employees' affective and performance outcomes: an empirical investigation of the New Zealand public healthcare sector
Authors: Ashill Nicholas J. , Carruthers Janet , Krisjanous Jayne 
Published: November 2006

Abstract

Very little attention has been given to understand the antecedents of service recovery performance in a public healthcare setting. In this study, a cross‐sectional survey investigates a model of service recovery performance. Frontline hospital employees completed a self‐administered questionnaire on how factors characterising management commitment to service quality (MCSQ) affect their service recovery efforts. The results suggest the influence of MCSQ is mediated by frontline employees' affective commitment to their hospital. The research advances understanding of frontline service recovery performance in a public healthcare setting and the findings indicate that public healthcare managers can take actions on a number of fronts to assist progress towards the achievement of frontline service recovery excellence.

Copyright © 2006 John Wiley & Sons, Ltd.
Effect of structure on solution and interfacial properties of sodium polystyrene sulfonate (NaPSS)
Authors: Sen Akhil Kumar , Roy Sandip , Juvekar Vinay A 
Published: November 2006

AbstractSodium polystyrene sulfonate (NaPSS) is synthesized by two different methods: one using free radical polymerization of sodium styrene sulfonate and another through post‐sulfonation of polystyrene. Both the solution and interfacial properties of the two polymers obtained from these two methods are different. The osmotic coefficient of free radically polymerized NaPSS is 20% higher than that of the NaPSS obtained from the post‐sulfonation method. Further, the free radically polymerized NaPSS has negligible interfacial activity at both air–water and toluene–water interfaces, as compared to post‐sulfonated NaPSS. The former type of NaPSS also adsorbs to a comparatively lesser extent at a solid–liquid interface. The enhanced hydrophobic character of post‐sulfonated NaPSS is explained on the basis of its intrinsically lower configurational entropy that results from the formation of intramolecular sulfone linkages, whereas the free radical method gives only a linear structure. Also, the intramolecular sulfone linkage will enhance the counter‐ion condensation and consequently decrease the osmotic coefficient of the post‐sulfonated sample. However, it is generally difficult to predict the exact degree of intramolecular sulfone linkage that may occur, as it depends on several factors. An attempt has been made to interpret some of the experimental data in the existing literature on NaPSS, which has mostly been prepared using the post‐sulfonation route. Copyright © 2006 Society of Chemical Industry
Temperature‐responsive characteristics of poly(N‐isopropylacrylamide) hydrogels with macroporous structure
Authors: Çaykara Tuncer , Kiper Simin , Demirel Gökhan , Demirci Serkan , Çakanyıldırım Çetin 
Published: November 2006

AbstractMacroporous poly(N‐isopropylacrylamide) (PNIPA) hydrogels were synthesized by free‐radical crosslinking polymerization in aqueous solution from N‐isopropylacrylamide monomer and N,N‐methylenebis (acrylamide) crosslinker using poly(ethylene glycol) (PEG) with three different number‐average molecular weights of 300, 600 and 1000 g mol−1 as the pore‐forming agent. The influence of the molecular weight and amount of PEG pore‐forming agent on the swelling ratio and network parameters such as polymer–solvent interaction parameter (χ) and crosslinking density (νE) of the hydrogels is reported and discussed. Scanning electron micrographs reveal that the macroporous network structure of the hydrogels can be adjusted by applying different molecular weights and compositions of PEG during polymerization. At a temperature below the volume phase transition temperature, the macroporous hydrogels absorbed larger amounts of water compared to that of conventional PNIPA hydrogels, and showed higher equilibrated swelling ratios in aqueous medium. Particularly, the unique macroporous structure provides numerous water channels for water diffusion in or out of the matrix and, therefore, an improved response rate to external temperature changes during the swelling and deswelling process. These macroporous PNIPA hydrogels may be useful for potential applications in controlled release of macromolecular active agents. Copyright © 2006 Society of Chemical Industry
Esophageal stent improves ventilation in a child with a broncho‐esophageal fistula caused by Mycobacterium tuberculosis
Authors: Goussard P. , Sidler D. , Kling S. , Andronikou S. , Rossouw G. F. , Gie R. P. 
Published: November 2006

AbstractThe deployment of an esophageal stent to aid in the ventilation of a child who had developed an acquired broncho‐esophageal fistula caused by Mycobacterium tuberculosis (MTB) is described. The 12‐month‐old boy presented with respiratory failure requiring ventilation. The air leak via the fistula led to inadequate mechanical ventilation. The deployment of the stent resulted in successful ventilation, closure of the fistula, and eventual successful treatment. Pediatr Pulmonol. 2007; 42:93–97. © 2006 Wiley‐Liss, Inc.
Limited tendency of α‐helical residues to form disulfide bridges: a structural explanation
Authors: De Simone Alfonso , Berisio Rita , Zagari Adriana , Vitagliano Luigi 
Published: November 2006

AbstractDisulfide bridges have an enormous impact on the structure of a large number of proteins and polypeptides. Understanding the structural basis that regulates their formation may be important for the design of novel peptide‐based molecules with a specific fold and stability. Here we report a statistical analysis of the relationships between secondary structure and disulfide bond formation, carried out using a large database of protein structures. Our analyses confirm the observation sporadically reported in previous investigations that cysteine residues located in α‐helices display a limited tendency to form disulfide bridges. The very low occurrence of the disulfide bond in all α‐chains compared to all β‐chains indicates that this property is also evident when proteins with different topologies are investigated. Taking advantage of the large database that endorsed the analysis on relatively rare motifs, we demonstrate that cysteine residues embedded in 310 helices present a good tendency to form disulfide bonds. This result is somewhat surprising since 310 helices are commonly assimilated into α‐helices. A plausible structural explanation for the observed data has been derived combining analyses of disulfide bond sequence separation and of the length of the different secondary structure elements. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd.
Interactions of amphipathic carrier peptides with membrane components in relation with their ability to deliver therapeutics
Authors: Deshayes Sébastien , Morris May C. , Divita Gilles , Heitz Frédéric 
Published: November 2006

AbstractTo identify rules for the design of efficient CPPs that can deliver therapeutic agents such as nucleic acids (DNAs, siRNAs) or proteins and PNAs into subcellular compartments, we compared the properties of several primary and secondary amphipathic CPPs. Studies performed with lipid monolayers at the air–water interface have enabled identification of the nature of the lipid–peptide interactions and characterization of the influence of phospholipids on the ability of these peptides to penetrate into lipidic media. Penetration and compression experiments reveal that both peptides interact strongly with phospholipids, and observations on Langmuir–Blodgett transfers indicate that they can modify the lipid organization. Conformational investigations indicate that the lipid–peptide interactions govern the conformational state(s) of the peptides. On the basis of the ability of both peptides to promote ion permeation through both natural and artificial membranes, models illustrating the translocation processes have been proposed. One is based on the formation of a β‐barrel pore‐like structure while another is based on the association of helices. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd.
Exploring interaction of β‐amyloid segment (25–35) with membrane models through paramagnetic probes
Authors: Esposito Cinzia , Tedeschi Annamaria , Scrima Mario , D'errico Gerardino , Ottaviani M. Francesca , Rovero Paolo , D'ursi Anna Maria 
Published: November 2006

AbstractThe accumulation of β‐amyloid peptides into senile plaques is one of the hallmarks of Alzheimer's disease (AD). There is mounting evidence that the lipid matrix of neuronal cell membranes plays an important role in the β‐sheet oligomerization process of β‐amyloid. Aβ(25–35), the sequence of which is GSNKGAIIGLM, is a highly toxic segment of amyloid β (Aβ)‐peptides, which forms fibrillary aggregates. In the present work, two spin‐labelled Aβ(25–35) analogues containing the nitroxide group of the amino acid TOAC (2,2,6,6‐tetramethylpiperidine‐1‐oxyl‐4‐amino‐4‐carboxylic acid) as a paramagnetic probe at the N‐ or the C‐terminus of the peptide sequence, respectively, were synthesized in order to investigate the peptide‐membrane interaction. The orientation and associated changes of the peptide conformation in the presence of different artificial membrane models (micelles, liposomes) were evaluated by electron paramagnetic resonance and circular dichroism techniques. The results of this study allowed us to propose a model in which the C‐terminal portion of the peptide is highly associated to the membrane, while the N‐terminal part extends into the aqueous phase with occasional contacts with the lipid head‐group region. Interestingly, the interaction of the C‐terminal portion of the peptide is particularly enhanced in the presence of sodium dodecyl sulfate (SDS) molecules. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd.
Method for the synthesis of highly pure vaccines using the lipid core peptide system
Authors: Moyle Peter M. , Olive Colleen , Good Michael F. , Toth Istvan 
Published: November 2006

AbstractTraditional vaccines consisting of whole attenuated microorganisms, killed microorganisms, or microbial components, administered with an adjuvant (e.g. alum), have been proved to be extremely successful. However, to develop new vaccines, or to improve upon current vaccines, new vaccine development techniques are required. Peptide vaccines offer the capacity to administer only the minimal microbial components necessary to elicit appropriate immune responses, minimizing the risk of vaccination associated adverse effects, and focusing the immune response toward important antigens. Peptide vaccines, however, are generally poorly immunogenic, necessitating administration with powerful, and potentially toxic adjuvants. The attachment of lipids to peptide antigens has been demonstrated as a potentially safe method for adjuvanting peptide epitopes. The lipid core peptide (LCP) system, which incorporates a lipidic adjuvant, carrier, and peptide epitopes into a single molecular entity, has been demonstrated to boost immunogenicity of attached peptide epitopes without the need for additional adjuvants. The synthesis of LCP systems normally yields a product that cannot be purified to homogeneity. The current study describes the development of methods for the synthesis of highly pure LCP analogs using native chemical ligation. Because of the highly lipophilic nature of the LCP lipid adjuvant, difficulties (e.g. poor solubility) were experienced with the ligation reactions. The addition of organic solvents to the ligation buffer solubilized lipidic species, but did not result in successful ligation reactions. In comparison, the addition of approximately 1% (w/v) sodium dodecyl sulfate (SDS) proved successful, enabling the synthesis of two highly pure, tri‐epitopic Streptococcus pyogenes LCP analogs. Subcutaneous immunization of B10.BR (H‐2k) mice with one of these vaccines, without the addition of any adjuvant, elicited high levels of systemic IgG antibodies against each of the incorporated peptides. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd.
Effects of N‐ and C‐terminal addition of oligolysines or native loop residues on the biophysical properties of transmembrane domain peptides from a G‐protein coupled receptor
Authors: Cano‐Sanchez Patricia , Severino Beatrice , Sureshbabu V. V. , Russo Joe , Inui Tatsuya , Ding Fa‐Xiang , Arshava Boris , Becker Jeff , Naider Fred 
Published: November 2006

AbstractTransmembrane domains (TMDs) of G‐protein coupled receptors (GPCRs) have very low water solubility and often aggregate during purification and biophysical investigations. To circumvent this problem many laboratories add oligolysines to the N‐ and C‐termini of peptides that correspond to a TMD. To systematically evaluate the effect of the oligolysines on the biophysical properties of a TMD we synthesized 21 peptides corresponding to either the second (TPIFIINQVSLFLIILHSALYFKY) or sixth (SFHILLIMSSQSLLVPSIIFILAYSLK) TMD of Ste2p, a GPCR from Saccharomyces cerevisiae. Added to the termini of these peptides were either Lysn (n = 1,2,3) or the corresponding native loop residues. The biophysical properties of the peptides were investigated by circular dichroism (CD) spectroscopy in trifluoroethanol–water mixtures, sodium dodecyl sulfate (SDS) micelles and dimyristoylphosphocholine (DMPC)‐dimyristoylphosphoglycerol (DMPG) vesicles, and by attenuated total reflection Fourier transform infrared (ATR‐FTIR) in DMPC/DMPG multilayers. The results show that the conformation assumed depends on the number of lysine residues and the sequence of the TMD. Identical peptides with native or an equal number of lysine residues exhibited different biophysical properties and structural tendencies. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd.
Probing DNA–peptide interaction forces at the single‐molecule level
Authors: Sewald Norbert , Wilking Sven D. , Eckel Rainer , Albu Silvia , Wollschläger Katrin , Gaus Katharina , Becker Anke , Bartels Frank W. , Ros Robert , Anselmetti Dario 
Published: November 2006

AbstractThe versatility of chemical peptide synthesis combined with the high sensitivity of AFM single‐molecule force spectroscopy allows us to investigate, quantify, and control molecular recognition processes (molecular nanotechnology), offering a tremendous potential in chemical biology.Single‐molecule force spectroscopy experiments are able to detect fast intermediate transition states, details of the energy landscape, and structural changes, while avoiding multiple binding events that can occur under ensemble conditions. Dynamic force spectroscopy (DFS) is even able to provide data on the complex lifetime. This minireview outlines the biophysical methodology, discusses different experimental set‐ups, and presents representative results in the form of two case studies, both dealing with DNA‐binding peptides. They may serve as model systems, e.g., for transcription factors or gene transfection agents. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd.