bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and characterization of novel pH‐sensitive binary grafted polymeric blends of gelatin and poly(vinyl alcohol): Water sorption and blood compatibility study
Authors: Bajpai A. K. , Sharma Manish 
Published: January 2006

AbstractIn this study, we attempted the synthesis and characterization of novel biocompatible hydrogels of binary polymeric blends of crosslinked poly(acrylic acid) grafted onto poly(vinyl alcohol) and gelatin by a redox polymerization technique. The end polymer was characterized by IR spectral analysis, differential scanning calorimetry measurements, and scanning electron microscopy. The prepared smart, environment‐responsive hydrogels, containing polyelectrolyte domains, were assessed for their water sorption potential under various experimental conditions and were further used to evaluate important network parameters such as the crosslink density, number of elastically effective chains, and molecular mass between crosslinks. The diffusion mechanism of the solvent–polymer interaction was also analyzed to predict the behavior of continuously relaxing chains containing several carboxylate ions. The blood compatibility of premeditated hydrogels was also judged by in vitro methods such as protein adsorption, blood clot formation, and hemolysis percentage assay measurement. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 599–617, 2006
Kenaf‐fiber‐reinforced poly(lactic acid) used for electronic products
Authors: Serizawa Shin , Inoue Kazuhiko , Iji Masatoshi 
Published: January 2006

AbstractWe have developed high‐performance biomass‐based plastics that consist of poly(lactic acid) (PLA) and kenaf fiber, which fixates CO2 efficiently. Adding this fiber to PLA greatly increases its heat resistance (distortion temperature under load) and modulus and also enhances its crystallization, so the ease of molding this material is improved. Eliminating the short particles from the kenaf fiber improves its effect on the impact strength. Kenaf fiber without the particles exhibits effects on these characteristics of PLA practically comparable to the effects of glass fiber. Furthermore, adding a flexibilizer (a copolymer of lactic acid and aliphatic polyester) to the composites improves their strength. These composites (PLA/kenaf fiber and PLA/kenaf fiber/flexibilizer) show good practical characteristics for housing materials of electronic products in comparison with petroleum‐based plastics used in housing such as glass‐fiber‐reinforced acrylonitrile‐butadien‐styrene (ABS) resin. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 618–624, 2006
Comparison of the molecular properties and morphology of polypropylenes irradiated under different atmospheres and after annealing
Authors: Krause Beate , Häußler Liane , Voigt Dieter 
Published: January 2006

AbstractElectron‐beam irradiation, a well‐known way of generating long‐chain branching, was used to modify polypropylene. Samples were investigated with differential scanning calorimetry, polarized light microscopy, and size exclusion chromatography. Independently of the atmosphere, postannealing led to the deactivation of residual radicals and to the reduction of the nucleus density. In comparison with the initial polypropylene, the crystallization temperatures increased for nonannealed samples but decreased for annealed samples. Stable products were obtained only by irradiation in nitrogen followed by annealing. A reaction including free radicals with oxygen in the ambient atmosphere led to increasing molar mass degradation and the formation of long‐chain branching after storage. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 634–639, 2006
Hydrogenation of natural rubber latex in the presence of OsHCl(CO)(O2)(PCy3)2
Authors: Mahittikul A. , Prasassarakich P. , Rempel G. L. 
Published: January 2006

AbstractHydrogenation is an important method of chemical modification, which improves the physical, chemical, and thermal properties of diene elastomers. Natural rubber latex (NRL) can be quantitatively hydrogenated to provide a strictly alternating ethylene–propylene copolymer using a homogeneous osmium catalyst OsHCl(CO)(O2)(PCy3)2. A detailed kinetic investigation was carried out by monitoring the amount of hydrogen consumption during the reaction using a gas‐uptake apparatus. The kinetic results of NRL hydrogenation indicated that this system had a second‐order dependence of the hydrogenation rate on hydrogen pressure and then decreased toward a zero‐order dependence for hydrogen pressures above 13.8 bar. The hydrogenation was also observed to be first‐order with respect to catalyst concentration and inverse first‐order on rubber concentration due to impurities present in the rubber latex. Additions of a controlled amount of acid demonstrated a beneficial effect on the hydrogenation rate of NRL. The temperature dependence of the hydrogenation rate was investigated and an apparent activation energy (over the range of 120–160°C) was calculated as 57.6 kJ/mol. Mechanistic aspects of this catalytic process are discussed on the basis of kinetic results. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 640–655, 2006
New polymer materials based on silicone‐acrylic copolymer to improve fastness properties of reactive dyes on cotton fabrics
Authors: Xie Kongliang , Hou Aiqin , Zhang Yuhao 
Published: January 2006

AbstractNew polymer materials, based on silicone‐acrylic copolymer containing cationic groups, were synthesized through radical mechanism and ring‐opening polymerization of cyclosiloxane. The polymers of polyacrylate/polysiloxane improved the fastness properties of reactive dyes on cotton. In comparison with those of polyacrylate‐containing cationic groups, the wash fastness and wet rubbing fastness of the dyed cotton fabric treated with the new polymer materials were better. The handle of the fabric with aftertreatment was also good. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 720–725, 2006
Self‐induced short chain branching in homopolymers and 1‐hexene copolymers of ethylene produced with amido functionalized ansa half‐sandwich complexes as catalysts
Authors: Alt Helmut G. , Reb Alexander , Bruce Welch M. , Jurkiewicz Antoni 
Published: January 2006

AbstractAmido ansa 3‐substituted indenyl complex precursors can be activated with methylaluminoxane and used for prepolymerization with ethylene to give a heterogeneous catalyst for olefin polymerization. Homo polymerization of ethylene with 1‐(3‐pent‐4‐enylindenylidene) dimethylsilyl'butylamidotitaniumdichloride (1), 1‐(3‐hex‐5‐enylindenylidene)dimethylsilyl'butylamidotitanium‐dichloride (2), and 1‐(3‐pent‐4‐enylindenylidene) (oct‐7‐enyl)methylsilyl'butylamidotitaniumdichloride (3) produces polyethylenes that contain ethyl branches. The ethyl branching in the polymers made with complexes 1 and 2 is barely above the 13C NMR detection limit, but the level observed in the polymer made with complex 3 is 17 times greater. Copolymerization of ethylene and 1‐hexene using prepolymerized 3 yields copolymers containing both ethyl and butyl branches. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 734–739, 2006
Transforming growth factor‐β and bone morphogenetic proteins: Cooperative players in chick and murine programmed retinal cell death
Authors: Franke Andreas G. , Gubbe Christian , Beier Marion , Duenker Nicole 
Published: January 2006

AbstractTransforming growth factor‐β (TGF‐β) and bone morphogenetic protein (BMP) are extracellular molecules known to mediate programmed cell death (PCD) in the developing retina. In the present study, we investigated the expression profiles and activity levels of ligands and receptors of the TGF‐β and BMP4 family during the physiological PCD periods of the developing chick and mouse retina and possible interactions of both proapoptotic molecules in mediating apoptosis in chick and murine retinal whole‐mount cultures. Immunocytochemical double‐labeling studies with the established ganglion cell marker Islet revealed overlapping expression patterns for TGF‐β and BMP4 ligands and receptors on the surface of retinal ganglion cells. The biphasic peak of activity and expression levels of TGF‐β and BMP4 ligands and receptors, revealed by Western blots and mink lung epithelial cell (MLEC) assays, coincided with the two main periods of retinal chick and murine PCD. In organotypic retinal cultures, we were able to increase apoptosis over basal levels by application of recombinant TGF‐β or BMP4. Double‐factor treatment induced an additional increase of apoptosis, suggesting a cooperation of both proapoptotic pathways. A significant increase in the number of apoptotic cells in the ganglion cell layer was observed in a TUNEL staining of retinal whole mounts treated with recombinant TGF‐β or BMP4, suggesting a concerted action of both factors in triggering ganglion cell death. Blockage experiments revealed that both pathways do not interact at the ligand, receptor, or Smad protein level but converge at the transcriptional level of the TGF‐β immediate‐early response gene TIEG and the transcriptional coactivator Gcn5. J. Comp. Neurol. 495:263–278, 2006. © 2006 Wiley‐Liss, Inc.
Structural basis for developmentally regulated changes in cadherin function at synapses
Authors: Elste Alice M. , Benson Deanna L. 
Published: January 2006

AbstractMembers of the cadherin family of calcium‐dependent cell adhesion molecules can bind homophilically across central nervous system (CNS) synapses, but experimental evidence indicates the nature of their contribution to synapse structure and function changes over time. We asked whether changes in function correspond to differences in intrasynaptic distribution. Using quantitative immuno‐electronmicroscopy, we determined where cadherins are localized within synapses at key developmental stages in cultured hippocampal neurons and in hippocampus in vivo. At 5–6 days in culture, when most synapses are newly formed, cadherins are regularly and evenly distributed at synaptic clefts throughout the active zone. In contrast, at 14 days, when the majority of synapses are comparatively mature, cadherin labeling concentrates in discrete clusters. Such clusters can occur at any place within or immediately surrounding synaptic clefts. To assess whether this change in distribution is unique to neurons grown in culture, we compared the distribution of cadherins in the CA1 region of hippocampus at postnatal days 2, 3 (P2–3) and in adult. Consistent with our observations in cultured neurons, synapses in P2–3 hippocampus most often exhibit cadherins distributed regularly throughout the cleft, while adult synapses show predominantly discrete concentrations at single sites. The early developmental pattern of cadherin distribution can also be detected at occasional synapses in adult tissue. Such synapses also have morphological features consistent with immature synapses, suggesting that intrasynaptic cadherin distribution is a feature that may distinguish synapse age. J. Comp. Neurol. 495:324–335, 2006. © 2006 Wiley‐Liss, Inc.
Distributions of two gonadotropin‐releasing hormone receptor types in a cichlid fish suggest functional specialization
Authors: Chen Chun‐Chun , Fernald Russell D. 
Published: January 2006

AbstractGonadotropin‐releasing hormone 1 (GnRH1) from the brain controls reproduction in vertebrates via a GnRH‐specific receptor in the pituitary; however, other forms of GnRH are found in all species, suggesting additional roles for this family of peptides. GnRH action depends critically on the location of its cognate receptors in the brain. To understand the potential roles of additional GnRH forms, we localized two known GnRH receptor types in a cichlid fish, Astatotilapia burtoni, in which GnRH1 is socially regulated. Using in situ hybridization, we describe the mRNA expression pattern of these GnRH receptor (GnRH‐R) subtypes in the brain, specifically with respect to GnRH‐producing neurons. Our data suggest that following a gene duplication, the two GnRH receptors have evolved to serve different functions. The type 1 receptor (GnRH‐R1) is expressed less widely than the type 2 receptor (GnRH‐R2). Specifically, GnRH‐R1 is expressed in groups of neurons in the telencephalon, preoptic area, ventral hypothalamus, thalamus, and pituitary. In contrast, GnRH‐R2 is expressed in many more brain areas, including the olfactory bulb, telencephalon, preoptic area, hypothalamus, thalamus, midbrain, optic tectum, cerebellum, hindbrain, and pituitary. The specific distribution of GnRH‐R2 suggests that the GnRH ligands may act via this receptor to influence behavior in A. burtoni. Moreover, only GnRH‐R2 mRNA is colocalized in the three known groups of GnRH‐containing neurons, suggesting that any direct feedback regulation of GnRH by itself must act through this receptor type. Taken together, these data suggest that the two GnRH receptor types serve different functional roles in A. burtoni. J. Comp. Neurol. 495:314–323, 2006. © 2006 Wiley‐Liss, Inc.
Targeting dopamine D2 and cannabinoid‐1 (CB1) receptors in rat nucleus accumbens
Authors: Pickel Virgina M. , Chan Jane , Kearn Christopher S. , Mackie Kenneth 
Published: January 2006

AbstractThe nucleus accumbens (Acb) shell and core are essential components of neural circuitry mediating the reward and motor effects produced by activation of dopamine D2 or cannabinoid‐1 (CB1) receptors. D2 receptors can form heterodimeric complexes with cannabinoid‐1 (CB1) receptors and are also involved in control of the availability of both dopamine and endocannabinoids. Thus, the subcellular locations of D2 and CB1 receptors with respect to each other are implicit to their physiological actions in the Acb. We used electron microscopic immunocytochemistry to determine these locations in the Acb shell and core of rat brain. In each region, many neuronal profiles showed endomembrane and plasmalemmal distributions of one or both receptors. Approximately one‐third of the labeled profiles were somata and dendrites, some of which showed overlapping subcellular distributions of D2 and CB1 immunoreactivities. The remaining labeled profiles were small axons and axon terminals containing CB1 and/or D2 receptors. Of the labeled terminals forming recognizable synapses, ∼20% of those containing CB1 receptors contacted D2‐labeled dendrites, while conversely, almost 15% of those containing D2 receptors contacted CB1‐labeled dendrites. These results provide the first ultrastructural evidence that D2 and CB1 receptors in the Acb shell and core have subcellular distributions supporting both intracellular associations and local involvement of D2 receptors in making available endocannabinoids that are active on CB1 receptors in synaptic neurons. These distributions have direct relevance to the rewarding and euphoric as well as motor effects produced by marijuana and by addictive drugs enhancing dopamine levels in the Acb. J. Comp. Neurol. 495:299–313, 2006. © 2006 Wiley‐Liss, Inc.
Immunogold localization of phocein in dendritic spines
Authors: Haeberlé Anne‐Marie , Castets Francis , Bombarde Guy , Baillat Gilbert , Bailly Yannick 
Published: January 2006

AbstractPhocein, a widely expressed intracellular protein involved in clathrin‐ and dynamin‐dependent membrane dynamics, has been shown to interact with members of the striatin family of proteins, striatin, SG2NA, and zinedin. Immunogold labeling was performed to assess subcellular localization of phocein in neurons of the rodent cerebellar cortex and hippocampal Ammon's horn. Most of the phocein‐bound gold particles were located within dendritic thorns and spines of the cerebellar Purkinje cells and hippocampal pyramidal neurons, as observed previously for striatin in striatal neurons. The postsynaptic profiles containing phocein were engaged in asymmetric synapses with the main types of afferents in the cerebellum and in the hippocampus. In the cerebellum, phocein‐bound immunogold particle numbers ranged from 1–20 in ∼50% of the Purkinje cell spines. In these spines most of the immunogold particles were found in the neuroplasm (∼70%) and on nonsynaptic plasma membrane domains and related structures such as endocytic‐like profiles (∼18%). As soon as the first postnatal week, phocein was detected in the Purkinje cell somatic and dendritic thorns making asymmetric synapses with climbing fibers. During the following weeks the protein was located in the dendritic spines, as observed in the adult molecular layer. Finally, double immunogold labeling revealed a distribution of phocein and SG2NA suggesting that the two proteins could interact in the Purkinje cell spines. The early postnatal expression of phocein, a protein involved in membrane dynamics, suggests that it may have functional relevance in dendritic remodeling during development and potentially in spine plasticity during adulthood. J. Comp. Neurol. 495:336–350, 2006. © 2006 Wiley‐Liss, Inc.
The Metal‐Catalyzed Cyclotrimerization of Ferrocenylethyne – Preparation and Characterization of 1,2,4‐Triferrocenylbenzene
Authors: Fiorentini Simone , Floris Barbara , Galloni Pierluca , Grepioni Fabrizia , Polito Mauro , Tagliatesta Pietro 
Published: January 2006

Abstract1,2,4‐Triferrocenylbenzene was isolated and fully characterized for the first time. It was obtained, together with 1,3,5‐triferrocenylbenzene, by cyclotrimerization reaction, catalyzed either by metalloporphyrins or cobaltocene. The latter catalyst gave better results. The isomerically different triferrocenylbenzenes exhibit different properties. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Novel Plastic Chromium(III)‐Ion Selective Electrodes Based on Different Ionophoric Species and Plasticizing Solvent Mediators
Authors: Akl Magda A. , Ghoneim Ahmed K. , Abd El‐Aziz Mohammed H. 
Published: January 2006

AbstractDifferent ionophoric species, viz.: 18‐crown‐6 (18C6), dibenzo‐18‐crown‐6 (DB18C6) and calix[6]arene (CAX), as electroactive materials, with 2‐nitrophenyloctylether (2‐NPOE), bis(ethylhexyl)sebacate (DOS), dioctyl phthalate (DOP), and didecyl phthalate (DDP) as plasticizing solvent mediators were used to construct Cr3+ selective electrodes in a PVC matrix in the ratio (w/w) PVC: ionophore: plasticizer (60 : 2 : 120). Seven electrodes out of the fabricated 12 electrodes, gave best results in terms of working concentration range (1.0×10−5−1.0×10−1 M) with a close to Nernstian slope of 18.5 and a Nernstian slope of 20.0 mV/decade of activity. The usable pH range of the sensors is 4.0–7.0. The detection limit of the selected electrodes is ≤1.0×10−7 M. The response time of the sensors is 8–35 s, depending on the concentration of Cr3+ used. The selectivity coefficient values indicate that the electrodes are highly selective for Cr3+ over a number of other cations except Pb2+ and Na+ (for some electrodes). The electrodes have successfully been used to determine Cr3+ in certified and real alloys and in effluents of electroplating shops with a precision as relative standard deviation (RSD)<3%, for each of the proposed Cr3+‐ion selective electrodes. The results obtained by the proposed ISEs are in good agreement with the results obtained by direct flame AAS method.
Plugs in nuclear pores: Transcripts in early oocyte development identified with nanotechniques
Authors: Schlune Andrea , Shahin Victor , Enss Karoline , Schillers Herman , Oberleithner Hans 
Published: January 2006

AbstractThroughout oogenesis, huge amounts of RNA are produced that are needed for early development. Early stages of oocyte development are characterized by high transcriptional activity whereas translation of maternal RNA dominates late stages. Nuclear pore complexes (NPCs), located in the nuclear envelope (NE), mediate bidirectional macromolecule exchange between the nuclear and cytosolic compartments including RNA export. Here, we report on structural correlates of this transport pathway at single NPC level. Using atomic force microscopy (AFM), we imaged the nucleoplasmic (“inner”) surface of the NE of Xenopus laevis oocytes in different stages of development. We found that NPC frequency per nucleus increases with maturation. However, individual NPCs are more active in immature stages. In early stages, known for high transcriptional activity, we found nearly 10% of NPC central channels plugged with a 400–800 kDa mass. In contrast, the incidence of plugged NPCs was below 1% in late oocyte stages. On‐site RNA digestion led to a change in plug shape from prominent to flat while plug mass decreased by almost 20%. Quantitative AFM analysis revealed that RNase exposure reduced total nucleoplasmic NPC mass by about 58 and 25% in early and late stage oocytes, respectively. We conclude: (i) NPCs of immature oocytes are more active in RNA transport, (ii) Plugs identified at the nucleoplasmic entrance of NPC central channels represent ribonucleoproteins exiting the nucleus, (iii) RNA is a structural component of the NPC nanomachine. J. Cell. Biochem. 98: 567–576, 2006. © 2006 Wiley‐Liss, Inc.
Effects of cadmium on structure and enzymatic activity of Cu,Zn‐SOD and oxidative status in neural cells
Authors: Huang Yen‐Hua , Shih Chwen‐Ming , Huang Chang‐Jen , Lin Chun‐Mao , Chou Chih‐Ming , Tsai Meng‐Ling , Liu Tsang Pai , Chiu Jen‐Fu , Chen Chien‐Tsu 
Published: January 2006

AbstractAmyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder disease. Ten percent of the ALS patients are congenital (familial ALS), and the other 90% are sporadic ALS (SALS). It has been shown that mutations found in the Cu,Zn‐SOD cause 20% of the familial ALS due to its low enzyme activity. We hypothesized that heavy metals may interfere the structure of Cu,Zn‐SOD protein to suppress its activity in some of the SALS. In this study, we expressed and characterized the recombinant human Cu,Zn‐SOD under various concentrations of Cu2+, Zn2+, and Cd2+. By atomic absorption spectrophotometry, we demonstrated that adding of cadmium significantly increased the content of cadmium ion, but reduced its Zn2+ content and enzyme activity of the Cu,Zn‐SOD protein. The data of circular dichroism spectra demonstrated that the secondary structure of Cu,Zn‐SOD/Cd is different from Cu,Zn‐SOD, but close to apo‐SOD. In addition to the effect of cadmium on Cu,Zn‐SOD, cadmium was also shown to induce neural cell apoptosis. To further investigate the mechanism of neural cell apoptosis induced by cadmium, we used proteomics to analyze the altered protein expressions in neural cells treated with cadmium. The altered proteins include cellular structural proteins, stress‐related and chaperone proteins, proteins involved in reactive oxygen species (ROS), enzyme proteins, and proteins that mediated cell death and survival signaling. Taken together, in this paper, we demonstrate that cadmium decreases the content of Zn2+, changes the conformation of Cu,Zn‐SOD protein to decrease its enzyme activity, and causes oxidative stress‐induced neural cell apoptosis. J. Cell. Biochem. 98: 577–589, 2006. © 2006 Wiley‐Liss, Inc.