bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plant oil‐based biofoam composites with balanced performance
Authors: Wu Su Ping , Qiu Jun Feng , Rong Min Zhi , Zhang Ming Qiu , Zhang Li Yang 
Published: February 2009

AbstractBACKGROUND: Biofoam composites were prepared using short sisal fibers as reinforcement and acrylated epoxidized soybean oil as matrix, aiming at replacing traditional unsaturated polyester foams in structural applications. The compressive properties of the composites were examined as a function of fiber loading, fiber length and foam density.RESULTS: The foam composite with 10 phr (parts per hundred of base resin by weight) sisal fiber possessed properties similar to those of commercial unsaturated polyester foams. A study of the failure mechanism revealed that debonding between fiber and matrix was a key issue responsible for catastrophic damage of the composites. According to this finding, surface pre‐treatment of the sisal using an alkali or silane coupling agent was carried out. This brought about positive effects on interfacial interaction and compressive strength of the composites, as desired. Also, soil burial tests proved that the foam composites could be biodegraded, and the incorporated sisal fibers accelerated the biodegradation of the composites.CONCLUSION: This work shows the feasibility of making rigid biofoams from natural resources, which could be potential candidates for structural foams. Copyright © 2009 Society of Chemical Industry
Characterisation of Plasmodium invasive organelles; an ookinete microneme proteome
Authors: Lal Kalpana , Prieto Judith Helena , Bromley Elizabeth , Sanderson Sanya J. , Yates John R. , Wastling Jonathan M. , Tomley Fiona M. , Sinden Robert E. 
Published: February 2009

AbstractSecretion of microneme proteins is essential to Plasmodium invasion but the molecular composition of these secretory organelles remains poorly defined. Here, we describe the first Plasmodium microneme proteome. Purification of micronemes by subcellular fractionation from cultured ookinetes was confirmed by enrichment of known micronemal proteins and electron microscopy. Quantitation of electron micrographs showed >14‐fold microneme enrichment compared to the intact ookinete, such that micronemes comprised 85% of the identifiable organelles in the fraction. Gel LC‐MS/MS of the most abundant protein constituents of the fraction identified three known micronemal proteins chitinase, CTRP, SOAP, together with protein disulphide isomerase (PDI) and HSP70. Highly sensitive MudPIT shotgun proteomics described a total of 345 proteins in the fraction. M1 aminopeptidase and PDI, the former a recognised target of drug development, were both shown to have a micronemal location by IFA. We further identified numerous proteins with established vesicle trafficking and signaling functions consistent with micronemes being part of a regulated secretory pathway. Previously uncharacterised proteins comprise the largest functional group of the microneme proteome and will include secreted proteins important to invasion.
A proteomic evaluation of Pyrenophora tritici‐repentis, causal agent of tan spot of wheat, reveals major differences between virulent and avirulent isolates
Authors: Cao Tiesen , Kim Yong Min , Kav Nat N. V. , Strelkov Stephen E. 
Published: February 2009

AbstractPyrenophora tritici‐repentis causes tan spot, an important foliar disease of wheat. The fungus produces multiple host‐specific toxins, including Ptr ToxB, a chlorosis‐inducing protein encoded by the ToxB gene. A homolog of ToxB is also found in avirulent isolates of the fungus. In order to improve understanding of the role of this homolog and evaluate the general pathogenic ability of P. tritici‐repentis, we compared the proteomes of avirulent race 4 and virulent race 5 isolates of the pathogen. Western blotting analysis revealed the presence of Ptr ToxB in spore germination and culture fluids of race 5 but not race 4. A comprehensive proteome‐level comparison by 2‐DE indicated 133 differentially abundant proteins in the secretome (29 proteins) and mycelium (104 proteins) of races 4 and 5, of which 63 were identified by MS/MS. A number of the proteins found to be up‐regulated in race 5 have been implicated in microbial virulence in other pathosystems, and included the secreted enzymes α‐mannosidase and exo‐β‐1,3‐glucanase, heat‐shock and BiP proteins, and various metabolic enzymes. These proteome‐level differences suggest a reduced general pathogenic ability in race 4 of P. tritici‐repentis, irrespective of toxin production. Such differences may reflect an adaptation to a saprophytic habit.
Actin, gelsolin and filamin‐A are dynamic actors in the cytoskeleton remodelling contributing to the blood brain barrier phenotype
Authors: Pottiez Gwënaël , Sevin Emmanuel , Cecchelli Roméo , Karamanos Yannis , Flahaut Christophe 
Published: February 2009

AbstractThe brain vascular endothelium operates as a dynamic regulatory interface to maintain the cell environment of the nervous system. In the vicinity of astrocytes, brain endothelial cells develop characteristic features conferring a strong cellular impermeability which limits the penetration of various compounds. The aim of our study was to determine by differential proteomic analysis the changes occurring in bovine brain capillary endothelial cells (BBCEC) differentiated in co‐culture with astrocytes compared with endothelial cells cultured alone. In order to obtain reproducible and meaningful protein profiles of in vitro blood–brain barrier models, three sample preparation procedures were carried out to provide the first 2‐D comparative proteomic study of BBCEC. Our study highlights advantages and drawbacks of each procedure. The cellular proteins prepared from mechanical scraping of collagen‐seeded BBCEC were strongly contaminated by serum proteins. Enzymatic dissociation of BBCEC by trypsin or collagenase solved this problem. A comparative 2‐DE profile study of collagenase‐harvested BBCEC revealed that cytoskeleton‐related proteins (actin, gelsolin and filamin‐A) show the most significant quantitative changes in the Triton soluble protein fraction from BBCEC that exhibit characteristics closest to the in vivo situation.
Mining the Leishmania genome for novel antigens and vaccine candidates
Authors: Herrera‐Najera Carla , Piña‐Aguilar Raúl , Xacur‐Garcia Fiona , Ramirez‐Sierra Maria Jesus , Dumonteil Eric 
Published: February 2009

AbstractLeishmaniasis is a neglected disease with an estimated 12 million infected people. The recent completion of the sequencing of the Leishmania major genome has opened opportunities for the identification of targets for vaccine development. We present here the first attempt at identifying novel vaccine candidates by whole genome analysis. We predicted CD8+ T cell epitopes from the L. major proteome and validated in vivo in mice the immunogenicity of some of the best predicted epitopes. Consensus epitope predictions from 8272 annotated protein sequences with 5–8 different algorithms allowed the identification of 78 class I CD8+ epitopes. BALB/c mice were immunized with 26 synthetic peptides corresponding to the most likely epitopes. Fourteen (54%) resulted immunogenic, with eight being strong inducers of T cell IFNγ production. None of the proteins from which the epitopes are derived are differentially expressed, only two may be surface proteins, eight have putative enzymatic, and metabolic activities. These epitopes and proteins represent new antigen candidates for further studies. While pathogen genomes have not yet delivered their full promise in terms of human health applications, our study opens the way for extensive genome mining for antigen identification and vaccine development against Leishmania and other pathogens.
Internal and external factors influencing the Diels–Alder reaction
Authors: Kiselev Vladimir D. , Konovalov Alexander I. 
Published: February 2009

AbstractThe internal and external key factors influencing the reaction rates were considered for the Diels–Alder reaction (DAR) with normal electron demand. A simple dependence lgk2 = −28.81 +316.3/(IPD−EA)−69.9 R1–4/(IPD−EA)−0.054ΔHr‐n for the reaction rate as a function of the ionization potential of π‐donor dienes, electron affinity of π–acceptor dienophiles, heat of reaction and diene structure (R1–4) was obtained. This relation allows one to explain the origin of the conventional and ‘anomalous’ relations between activity and selectivity, and the variety of relationships between the kinetic activity and thermodynamic stability. It helps one to choose the conditions for the directed synthesis of desired products, to explain the acceleration effects in the presence of Lewis acids and to predict the rates of the DAR between the different reagents with CC bonds not explored earlier. Copyright © 2009 John Wiley & Sons, Ltd.
Synthesis and characterization of a new ethynyl‐linked alternating anthracene/fluorene copolymer for organic thin film transistor
Authors: Ju Jin Uk , Chung Dae Sung , Kim Seul Ong , Jung Sung Ouk , Park Chan Eon , Kim Yun‐Hi , Kwon Soon‐Ki 
Published: February 2009

AbstractA new p‐type conjugated copolymer, poly(9,10‐diethynylanthracene‐alt‐9,9‐didodecylfluorene) (PDADF), which is composed of ethynyl‐linked alternating anthracene/fluorene, is synthesized via a palladium(II)‐catalyzed Sonogashira coupling reaction with 9,10‐diethynylanthracene and 2,7‐diiodo‐9,9‐didodecyl‐fluorene. The obtained polymer is confirmed by FTIR, 1H‐NMR, 13C‐NMR and elemental analysis. The PDADF had very good solubility in organic solvents such as chloroform and had a weight average molecular weight of 29,300 with a polydispersity index of 1.29. The PL maximum of the polymer was found at 533 and 568 nm for a solution and 608 nm for film, respectively. The highest occupied molecular orbital (HOMO) energy of the polymer is −5.62 eV as measured via cyclic voltammetry (CV). A solution‐processed thin film transistor device showed a carrier mobility value of 6.0 × 10−4 cm2/Vs with a threshold voltage of −17 V and a capacitance (Ci) of 10 nF/cm2. The out‐of‐plane and in‐plane GIXD pattern of spin‐coated polymer on SiO2 dielectric surfaces showed an amorphous halo near 2θ = 20°. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1609–1616, 2009
Anionic alternating copolymerization of a bifunctional six‐membered lactone and glycidyl phenyl ether: Selective synthesis of a linear polyester having lactone moiety
Authors: Uenishi Kazuya , Sudo Atsushi , Endo Takeshi 
Published: February 2009

AbstractAn imidazole‐initiated copolymerization of an aromatic bislactone, 10‐methyl‐2H,8H‐benzo[1,2‐b:5,4‐b′]bipyran‐2,8‐dione (1), and glycidyl phenyl ether (GPE) was investigated. In spite of the bifunctional nature of 1 that would potentially permit formation of networked and thus insoluble polymers upon its copolymerization, only one of the two lactone moieties of 1 exclusively underwent the copolymerization to give a linear polyester. Spectroscopic analysis of the polyester and its reductive scission into the corresponding fragment revealed that the polyester was formed by a 1:1 alternating copolymerization of GPE and the lactone moiety of 1. The other lactone in 1 that did not participate in the copolymerization was quantitatively incorporated into the side chain of the polyester as a reactive site, of which ring‐opening reactions by amine and alcohol as nucleophilic reagents allowed chemoselective polymer reactions. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1661–1672, 2009
Azine bridge formation during the electrografting of acrylonitrile
Authors: Easter Penelope A. , Taylor D. Martin 
Published: February 2009

AbstractWe report the electrografting of polyacrylonitrile (PAN) films onto evaporated gold, silver, and copper substrates, and onto platinum foil. The FTIR spectra of the films are virtually identical to library spectra of PAN and show no evidence of the cyclization observed by some authors. Raman spectra of the same films, however, display a broad absorption band centered at ∼1520 cm−1 and a second band at 1096 cm−1, which are neither present in spin‐coated films of commercially obtained PAN nor are they present in the FTIR spectra. These previously unreported Raman bands are dependent on a number of factors in the electrografting process; the working electrode metal, the monomer concentration, the solvent used, and the electrochemical protocol used for cleaning the working electrode. The relative intensity of the bands was found to be strongest in films grown on platinum and weakest in those grown on gold, and stronger in thin films (<50 nm) than in thick films (>100 nm). We suggest that these new spectral features are associated with azine‐linked polymer chains in a ladder‐like structure close to the electrode surface as a result of the predominantly isotactic brush‐like conformation of the polymer during the early stages of electrografting. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1685–1695, 2009
RAFT polymerization of activated 4‐vinylbenzoates
Authors: Nilles Katja , Theato Patrick 
Published: February 2009

AbstractThe reversible addition fragmentation chain transfer (RAFT) polymerization of five active ester monomers based on 4‐vinylbenzoic acid had been investigated. Pentafluorophenyl 4‐vinylbenzoate could be polymerized under RAFT conditions yielding polymers with very good control over molecular weight and narrow molecular weight distributions. Following the synthesis of diblock copolymers consisting of polystyrene, polypentafluorostyrene, poly(4‐octylstyrene), or poly(4‐acetoxystyrene) as an inert block and poly(pentafluorophenyl 4‐vinylbenzoate) as a reactive block was successfully performed. The diblock copolymer poly(pentafluoro styrene)‐block‐poly(pentafluorophenyl 4‐vinylbenzoate) had been analyzed by 19F NMR spectroscopy in solution, demonstrating the synthetic potential of pentafluorophenyl 4‐vinylbenzoate as an extremely valuable monomer for the synthesis of highly functionalized polymeric architectures. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1696–1705, 2009
Levels of pollutants in indoor air and respiratory health in preschool children: A systematic review
Authors: Fuentes‐Leonarte Virginia , Tenías José M. , Ballester Ferran 
Published: February 2009

AbstractThe aim of this paper is thus to identify, evluate, and summarize in a systematic fashion all the epidemiological studies that have analyzed the association between exposure to specific indoor air pollutants and respiratory disease among children under the age of five. A search was carried out in the main biomedical bibliographica sources in December 2006 and updated in February 2008. The study period covered 12 years (1996–2007). All the selected papers were carefully read. We focused on studies that analyzed at least one indicator of respiratory health and which included one or more indoor air pollutants in relation to the respiratory health of children under the age of 5. Studies that analyzed passive smoking as the sole source of indoor air pollution were not included. Fourteen studies were considered to be relevant. The most analyzed pollutant was nitrogen dioxide, followed by volative organic compounds, airborne particulates and other pollutants; phthalates and CO2. The literature reviewed within our criteria seems to indicate that several indoor pollutants, even at the moderate levels found in the developed countries, could be harmful to the respiratory health of very young children. Future research should focus on conducting more studies, preferably making use of cohorts, with adequate techniques for measuring indooor pollution levels. Pediatr Pulmonol. 2009; 44:231–243. © 2009 Wiley‐Liss, Inc.
The effect of obesity on pulmonary lung function of school aged children in Greece
Authors: Spathopoulos Diogenis , Paraskakis Emmanouil , Trypsianis Grigorios , Tsalkidis Aggelos , Arvanitidou Vasiliki , Emporiadou Maria , Bouros Demosthenes , Chatzimichael Athanasios 
Published: February 2009

AbstractObesity impacts on many issues of pulmonary medicine, where it is debated if obesity is linked to asthma, atopy or altered lung function tests. Our study aimed to investigate primarily the effect of obesity on the lung function tests and secondary the possible link of obesity with atopy and asthma in a large cohort of children in Greece.Body mass index (BMI) and data from a questionnaire for lung health, atopy, nutritional habits and family history were obtained from 2,715 children aged 6–11 years. Six hundred fifty‐seven children with BMI>85th percentile (357 overweight, 300 obese) and a group of 196 normal weight children underwent spirometry. The % expected FVC, FEV1, FEF25–75, and FEV1/FVC were significantly reduced in overweight or obese children compared to children with normal weight (P = 0.007, P < 0.001, P < 0.001, and P < 0.001, respectively). Reported atopy was significantly higher in overweight or obese children compared to normal weight children (P = 0.008). High BMI remained a strong independent risk factor for asthma (OR = 2.17, 95% CI = 1.22–3.87, P = 0.009) and for atopy (OR = 2.06, 95% CI = 1.32–3.22, P = 0.002). The effect of increased BMI on asthma was significant in girls, but not in boys (OR = 2.73, 95% CI = 1.09–6.85, P = 0.032; OR = 1.74, 95% CI = 0.83–3.73, P = 0.137, respectively).In conclusion we have shown that high BMI remains an important determinant of reduced spirometric parameters, a risk factor for atopy in both genders and for asthma in girls. Pediatr Pulmonol. 2009; 44:273–280. © 2009 Wiley‐Liss, Inc.
Crystal structure of domain‐swapped STE20 OSR1 kinase domain
Authors: Lee Seung‐Jae , Cobb Melanie H. , Goldsmith Elizabeth J. 
Published: February 2009

AbstractOSR1 (oxidative stress‐responsive‐1) and SPAK (Ste20/Sps1‐related proline/alanine‐rich kinase) belong to the GCK‐VI subfamily of Ste20 group kinases. OSR1 and SPAK are key regulators of NKCCs (Na+/K+/2Cl− cotransporters) and activated by WNK family members (with‐no‐lysine kinase), mutations of which are known to cause Gordon syndrome, an autosomal dominant form of inherited hypertension. The crystal structure of OSR1 kinase domain has been solved at 2.25 Å. OSR1 forms a domain‐swapped dimer in an inactive conformation, in which P+1 loop and αEF helix are swapped between dimer‐related monomers. Structural alignment with nonswapped Ste20 TAO2 kinase indicates that the integrity of chemical interactions in the kinase domain is well preserved in the domain‐swapped interfaces. The OSR1 kinase domain has now been added to a growing list of domain‐swapped protein kinases recently reported, suggesting that the domain‐swapping event provides an additional layer of complexity in regulating protein kinase activity.
A nonessential role for Arg 55 in cyclophilin18 for catalysis of proline isomerization during protein folding
Authors: Moparthi Satish Babu , Hammarström Per , Carlsson Uno 
Published: February 2009

AbstractThe protein folding process is often in vitro rate‐limited by slow cis‐trans proline isomerization steps. Importantly, the rate of this process in vivo is accelerated by prolyl isomerases (PPIases). The archetypal PPIase is the human cyclophilin 18 (Cyp18 or CypA), and Arg 55 has been demonstrated to play a crucial role when studying short peptide substrates in the catalytic action of Cyp18 by stabilizing the transition state of isomerization. However, in this study we show that a R55A mutant of Cyp18 is as efficient as the wild type to accelerate the refolding reaction of human carbonic anhydrase II (HCA II). Thus, it is evident that the active‐site located Arg 55 is not required for catalysis of the rate‐limiting prolyl cis‐trans isomerization steps during the folding of a protein substrate as HCA II. Nevertheless, catalysis of cis‐trans proline isomerization in HCA II occurs in the active‐site of Cyp18, since binding of the inhibitor cyclosporin A abolishes rate acceleration of the refolding reaction. Obviously, the catalytic mechanisms of Cyp18 can differ when acting upon a simple model peptide, four residues long, with easily accessible Pro residues compared with a large protein molecule undergoing folding with partly or completely buried Pro residues. In the latter case, the isomerization kinetics are significantly slower and simpler mechanistic factors such as desolvation and/or strain might operate during folding‐assisted catalysis, since binding to the hydrophobic active site is still a prerequisite for catalysis.
Investigating protein unfolding kinetics by pulse proteolysis
Authors: Na Yu‐Ran , Park Chiwook 
Published: February 2009

AbstractInvestigation of protein unfolding kinetics of proteins in crude samples may provide many exciting opportunities to study protein energetics under unconventional conditions. As an effort to develop a method with this capability, we employed “pulse proteolysis” to investigate protein unfolding kinetics. Pulse proteolysis has been shown to be an effective and facile method to determine global stability of proteins by exploiting the difference in proteolytic susceptibilities between folded and unfolded proteins. Electrophoretic separation after proteolysis allows monitoring protein unfolding without protein purification. We employed pulse proteolysis to determine unfolding kinetics of E. coli maltose binding protein (MBP) and E. coli ribonuclease H (RNase H). The unfolding kinetic constants determined by pulse proteolysis are in good agreement with those determined by circular dichroism. We then determined an unfolding kinetic constant of overexpressed MBP in a cell lysate. An accurate unfolding kinetic constant was successfully determined with the unpurified MBP. Also, we investigated the effect of ligand binding on unfolding kinetics of MBP using pulse proteolysis. On the basis of a kinetic model for unfolding of MBP•maltose complex, we have determined the dissociation equilibrium constant (Kd) of the complex from unfolding kinetic constants, which is also in good agreement with known Kd values of the complex. These results clearly demonstrate the feasibility and the accuracy of pulse proteolysis as a quantitative probe to investigate protein unfolding kinetics.
Design of a heterotetrameric coiled coil
Authors: Root Benjamin C. , Pellegrino Laurel D. , Crawford Emily D. , Kokona Bashkim , Fairman Robert 
Published: February 2009

AbstractWe have successfully designed a simple peptide sequence that forms highly stable coiled‐coil heterotetramers. Our model system is based on the GCN4‐pLI parallel coiled‐coil tetramer, first described by Kim and coworkers (Harbury et al., Science 1993;262:1401–1407). We introduced glutamates at all of the e and c heptad positions of one sequence (ecE) and lysines at the same positions in a second sequence (ecK). Based on a modeling study, these sidechains are close enough in space to form structure‐stabilizing salt bridges. We show that ecE and ecK are highly unstable by themselves but form very stable parallel helical tetramers when mixed, as judged by circular dichroism, analytical ultracentrifugation, and disulfide crosslinking studies. The origin of the difference in stabilities between the homomeric structures and the heteromeric structures comes from a combination of the relief of electrostatic repulsions with concomitant formation of electrostatic attractive interactions based on pH and NaCl screening experiments. We quantify the stability of the heterotetrameric coiled coil from a thermodynamic analysis and compare the finding to other similar coiled‐coil systems.