bluuebunny/crossref_metadata_2025 huggingface dataset:
Modulation of glioma BK channels via erbB2
Authors: Olsen M.L. , Weaver A.K. , Ritch P.S. , Sontheimer H.
Published: June 2005

Glioma cells show up‐regulation and constitutive activation of erbB2, and its expression correlates positively with increased malignancy. A similar correlation has been demonstrated for the expression of gBK, a calcium‐sensitive, large‐conductance K+ channel. We show here that glioma BK channels are a downstream target of erbB2/neuregulin signaling. Tyrphostin AG825 was able to disrupt the constituitive erbB2 activation in a dose‐dependent manner, causing a 30‐mV positive shift in gBK channel activation in cell‐attached patches. Conversely, maximal stimulation of erbB2 with a recombinant neuregulin (NRG‐1β) caused a 12‐mV shift in the opposite direction. RT‐PCR studies reveal no change in the BK splice variants expressed in treated glioma cells. Furthermore, isolation of surface proteins through biotinylation did not show a change in gBK channel expression, and probing with phospho‐specific antibodies showed no alteration in channel phosphorylation. However, fura‐II Ca2+ fluorescence imaging revealed a 35% decrease in the free intracellular Ca2+ concentration after erbB2 inhibition and an increase in NRG‐1β‐treated cells, suggesting that the observed changes most likely were due to alterations in [Ca2+]i. Consistent with this conclusion, neither tyrphostin AG825 nor NRG‐1β was able to modulate gBK channels under inside‐out or whole‐cell recording conditions when intracellular Ca2+ was fixed. Thus, gBK channels are a downstream target for the abundantly expressed neuregulin‐1 receptor erbB2 in glioma cells. However, unlike the case in other systems, this modulation appears to occur via changes in [Ca2+]i without changes in channel expression or phosphorylation. The enhanced sensitivity of gBK channels in glioma cells to small, physiological Ca2+ changes appears to be a prerequisite for this modulation. © 2005 Wiley‐Liss, Inc.
Human Gas7 isoforms homologous to mouse transcripts differentially induce neurite outgrowth
Authors: Chao Chuck C.‐K. , Chang P.‐Y. , Lu Henry H.‐P.
Published: June 2005

Gas7, a growth‐arrest‐specific protein, is expressed preferentially in the brain and is required for neurite outgrowth in cultured cerebellar and peripheral murine neurons. Gas7 interacts with F‐actin and colocalizes with the terminal part of actin microfilament in cells in which membrane outgrowth is present. Gas7 isoforms were discovered in murine brain by alternative splicing. This work reports the identification of two human Gas7 cDNA: hGas7‐a with 2,427 nucleotides, which encodes 330 amino acids, and hGas7‐b with 2,610 nucleotides, which encodes 412 amino acids according to predicted open‐reading‐frames. The predicted hGas7‐b protein is 97% homologous to murine homologues, whereas the hGas7‐a is homologous to the mouse Gas7‐cb form that is expressed preferentially in cerebellum. Alignment analysis of the Gas7 protein sequences revealed a high homology to that in humans: 99% for the monkey, 97% in murine, and around 75% for the puffer fish and chicken. The hGas7‐b protein comprises a WW domain, which often associates with other domains that are typically present in proteins in signal transduction processes, and an FCH domain, which participates in rearranging the cytoskeleton. The hGas7‐a comprises only the FCH domain. Analysis of the human Gas7 sequences using the DNA database revealed that the two forms resulted from the canonical alternative splicing of a Gas7 genomic sequence. The abundance of both hGas7 mRNA levels, determined by quantitative PCR in tissues including brain, breast cancer, placenta, and head‐neck cancer, revealed that the level of hGas7‐a was 14 times that of hGas7‐b in these tissues. Transfection of cells with hGas7‐a or hGas7‐b cDNA yielded the predicted 38‐kDa or 50‐kDa protein, respectively. The ectopic expression of hGas7 caused neurite‐like cell processes in both mouse Neuro‐2a and human SH‐SY5Y neuroblastoma cells. Interestingly, the hGas7‐a preferentially elicited the small lamellipodia, whereas the hGas7‐b elicited the small filopodia phenotype. These findings reveal the evolutionary conservation of the structure and function of Gas7. They also suggest that the FCH domain in Gas7 may participate in the development of lamellipodia, and the WW domain may participate in the fine‐tuning of the filopodia. © 2005 Wiley‐Liss, Inc.
Manganese transport by rat brain endothelial (RBE4) cell‐based transwell model in the presence of astrocyte conditioned media
Authors: Fitsanakis Vanessa A. , Piccola Greg , Aschner Judy L. , Aschner Michael
Published: June 2005

Manganese (Mn), an essential nutrient, is neurotoxic at high levels and has been associated with the development of a parkinsonian syndrome termedmanganism. Currently, the mechanisms responsible for transporting Mn across the blood–brain barrier (BBB) are unknown. By using rat brain endothelial 4 (RBE4) cell monolayers cultured in astrocyte‐conditioned media (ACM), we examine the effects of temperature, energy, proton (pH), iron (Fe), and sodium (Na+) dependence on Mn transport. Our results suggest that Mn transport is temperature, energy, and pH dependent, but not Fe or Na+dependent. These data suggest that Mn transport across the BBB is an active process, but they also demonstrate that the presence of ACM in endothelial cell cultures decreases the permeability of these cells to Mn, reinforcing the use of ACM or astrocyte cocultures in studies examining metal transport across the BBB. © 2005 Wiley‐Liss, Inc.
Suppression of Stat3 promotes neurogenesis in cultured neural stem cells
Authors: Gu Feng , Hata Ryuji , Ma Yong‐Jie , Tanaka Junya , Mitsuda Noriaki , Kumon Yoshiaki , Hanakawa Yasushi , Hashimoto Koji , Nakajima Koichi , Sakanaka Masahiro
Published: June 2005

To investigate the effects of signal transducer and activator of transcription 3 (Stat3) on neural stem cell fate, stem cells were inoculated with an adenovirus vector expressing dominant negative form of Stat3 (Stat3F). One day later, a promoter assay revealed significant reduction of the transcriptional level in the transfected cells. Three days later, Western blot analysis and immunocytochemical analysis revealed that the protein level of microtubule‐associated protein (MAP)2 and the number of MAP2‐positive cells were increased significantly in the transfected cells whereas the protein level of glial fibrillary acidic protein (GFAP) and the number of GFAP‐positive cells were decreased significantly. In addition, mRNA levels of Notch family members (Notch1, 2, and 3) and of inhibitory basic helix‐loop‐helix (bHLH) factors (Hes5, Id2, and Id3) were significantly downregulated at 3 days after viral inoculation with Stat3F; however, mRNA levels of bHLH determination factors (Math1 and Neurogenin3) and bHLH differentiation factors (NeuroD1 and NeuroD2) were significantly upregulated. These data indicated that suppression of Stat3 directly induced neurogenesis and inhibited astrogliogenesis in neural stem cells. © 2005 Wiley‐Liss, Inc.
Changes in neuronal protein 22 expression and cytoskeletal association in the alcohol‐dependent and withdrawn rat brain
Authors: Depaz Iris M. , de las Heras Rachel , Kroon Paulus A. , Wilce Peter A.
Published: June 2005

The action of alcohol on neuronal pathways has been an issue of increasing research focus, with numerous findings contradicting the previously accepted idea that its effect is nonspecific. The human NP22 (hNP22) gene was revealed by its elevated expression in the frontal cortex of the human alcoholic. The sequences of hNP22 and the rat orthologue rNP22 contain a number of domains consistent with those of cytoskeletal‐interacting proteins. Localization of rNP22 is restricted to the cytoplasm and processes of neurons and it colocalizes with elements of the microfilament and microtubule matrices including filamentous actin (F‐actin), α‐tubulin, tau, and microtubule‐associated protein 2 (MAP2). Withdrawal of Wistar rats after alcohol dependence induced by alcohol vapor produced elevated levels of rNP22 mRNA and protein in the cortex, CA2, and dentate gyrus regions of the hippocampus. In contrast, there was decreased rNP22 expression in the striatum after chronic ethanol exposure. Chronic ethanol exposure did not markedly alter rNP22 colocalization with F‐actin, α‐tubulin, or MAP2, although colocalization at the periphery of the neuronal soma with F‐actin was observed only after chronic ethanol exposure and withdrawal. Rat NP22 colocalization with MAP2 was reduced during withdrawal, whereas association with α‐tubulin and actin was maintained. These findings suggest that the effect of chronic ethanol exposure and withdrawal on rNP22 expression is region selective. Rat NP22 may affect microtubule or microfilament function, thereby regulating the neuroplastic changes associated with the development of alcohol dependence and physical withdrawal. © 2005 Wiley‐Liss, Inc.
Phosphatidic acid and diacylglycerol generation is regulated by insulin in cerebral cortex synaptosomes from adult and aged rats
Authors: Salvador Gabriela A. , Ilincheta de Boschero Monica G. , Pasquaré Susana J. , Giusto Norma M.
Published: June 2005

Insulin receptor associated with the cerebral cortex (CC) has been shown to be involved in brain cognitive functions. Furthermore, deterioration of insulin signaling has been associated with age‐related brain degeneration. We have reported previously that aging stimulates phospholipase D/phosphatidate phosphohydrolase 2 (PLD/PAP2) pathway in CC synaptosomes from aged rats, generating a differential availability of their reaction products: diacylglycerol (DAG) and phosphatidic acid (PA). The aim of this work was to determine the effect of aging on DAG kinase (DAGK), as an alternative pathway for PA generation, and to evaluate the effect of insulin on PLD/PAP2 pathway and DAGK. PLD, PAP2, and DAGK activities were measured using specific radiolabeled substrates in CC synaptosomes from adult (4 months old) and aged rats (28 months old). In adult animals, in the presence of the tyrosine phosphatase inhibitor (sodium o‐vanadate), insulin stimulated PLD activity at 5 min incubation. DAGK activity was also increased at the same time of incubation and PAP2 was inhibited. In aged animals, PLD activity was not modified by the presence of insulin plus vanadate, PAP2 was inhibited, and DAGK was stimulated by the hormone. Insulin, vanadate, and the combination of both induced protein tyrosine phosphorylation in adult CC synaptosomes. Aged rats showed a lower level of protein phosphorylation with respect to adult rats. Our results show that insulin modulates PA and DAG availability through the regulation of PLD/PAP2 and DAGK pathways in adult rat CC synaptosomes. Additionally, we demonstrated that PA and DAG generation is regulated differentially by insulin during aging. © 2005 Wiley‐Liss, Inc.
Methyl‐4‐phenylpyridinium ion modulates expression of mitochondrial uncoupling proteins 2, 4, and 5 in catecholaminergic (SK‐N‐SH) cells
Authors: Ho Philip Wing‐Lok , Chan David Yiu‐Leung , Kwok Ken Hon‐Hung , Chu Andrew Chi‐Yuen , Ho Jessica Wing‐Man , Kung Michelle Hiu‐Wai , Ramsden David Boyer , Ho Shu‐Leong
Published: June 2005

Methyl‐4‐phenylpyridinium ion (MPP+), a specific dopaminergic neurotoxin, inhibits mitochondrial complex I activity, generates reactive oxygen species (ROS), reduces ATP production, and induces cell death. We explored changes in expression of uncoupling proteins (UCPs 2, 4, and 5) following MPP+‐induced toxicity in SK‐N‐SH cells over 72 hr at the transcriptional (quantification of mRNA by real‐time RT‐PCR) and translational (Western analysis) levels. UCP5 mRNA and protein were markedly up‐regulated (1 mM MPP+ at 72 hr caused a twofold increase, P < 0.01), as was UCP4 mRNA, albeit to a much lesser extent. Surprisingly, UCP2 mRNA levels decreased at 24 hr (P < 0.05) but thereafter significantly increased to greater than control levels at 72 hr (P < 0.05), although UCP2 protein levels were decreased throughout (1 mM MPP+ at 72 hr caused a reduction of 50%, P < 0.01). The increase in ROS production may be attenuated by UCP4 and UCP5 up‐regulation. The consequence of decreased UCP2 levels is unclear, although this may represent an adaptive response to declines in ATP levels, the subsequent increase in mRNA being a response to further increases in oxidative stress. © 2005 Wiley‐Liss, Inc.
The development of a suitable manufacturing process for ‘Benifuuki’ green tea beverage with anti‐allergic effects
Authors: Nagai Hiroshi , Maeda‐Yamamoto Mari , Suzuki Yuko , Sato Katsuhiko , Mitsuda Hiromichi
Published: June 2005

Epigallocatechin‐3‐O‐(3‐O‐methyl) gallate (EGCG3″Me) has been reported to inhibit type I allergy better than epigallocatechin gallate (EGCG), a major catechin in tea leaves (Camellia sinensis L). We examined the effects of extraction and sterilization on the catechin content and histamine release from mast cells, as a representative reaction of early phase allergy, in the manufacture of ‘Benifuuki’ green tea beverage. Among various varieties of tea, the cultivar ‘Benifuuki’ contains approximately 2% of EGCG3″Me. Ester‐type catechins and their epimers increased with the increased extraction temperature of the tea. A tea infusion, extracted at 90 °C, strongly inhibited histamine release from mast cells. Furthermore, sterilization affected the catechin content in the manufactured green tea beverage. Sterilization at high temperature promoted the isomerization of catechins and the sterilized green tea beverage had a strong inhibitory effect. When EGCG3″Me, EGCG, epicatechin‐3‐O‐gallate (ECG) and their epimers, GCG3″Me (gallocatechin‐3‐O‐(3‐O‐methyl) gallate), GCG (gallocatechin‐3‐O‐gallate) and CG (catechin‐3‐O‐gallate) were compared, the anti‐allergic effect of GCG3″Me was strongest, and the order of activity was GCG3″Me > EGCG3″Me > GCG > EGCG. We consequently suggest that it was necessary to extract components from tea at the highest temperature possible, and to pasteurize under retort conditions (118.1 °C, 20 min), to manufacture functional green tea beverage with an anti‐allergic action. Copyright © 2005 Society of Chemical Industry
Characterization of g∞,σ‐integral operators
Authors: Arango G. , López Molina J. A. , Rivera M. J.
Published: June 2005

The application of the general tensor norms theory of Defant and Floret to the ideal of (p, σ)‐absolutely continuous operators of Matter, 0 < σ < 1, 1 ≤ p < ∞ leads to the study of gp′,σ‐nuclear and gp′,σ‐integral operators. Characterizations of such operators has been obtained previously in the case p > 1. In this paper we characterize the g∞,σ‐nuclear and g∞,σ‐integral operators by the existence of factorizations of some special kinds. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Random vectors satisfying Khinchine–Kahane type inequalities for linear and quadratic forms
Authors: Bastero Jesús , Romance Miguel
Published: June 2005

We study the behaviour of moments of order p (1 < p < ∞) of affine and quadratic forms with respect to non log‐concave measures and we obtain an extension of Khinchine–Kahane inequality for new families of random vectors by using Pisier's inequalities for martingales. As a consequence, we get some estimates for the moments of affine and quadratic forms with respect to a tail volume of the unit ball of lnq (0 < q < 1). (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Norm estimates for a Kakeya‐type maximal operator
Authors: Mitsis Themis
Published: June 2005

We prove Lp → Lq estimates for the 2‐dimensional analog of the Kakeya maximal function. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Teichmüller curves, Galois actions and $ \widehat {GT} $‐relations
Authors: Möller Martin
Published: June 2005

Teichmüller curves are geodesic discs in Teichmüller space that project to algebraic curves C in the moduli space Mg. Some Teichmüller curves can be considered as components of Hurwitz spaces. We show that the absolute Galois group Gℚ acts faithfully on the set of these embedded curves.

We also compare the action of Gℚ on π1(C) with the one on π1(Mg) and obtain a relation in the Grothendieck–Teichmüller group, seemingly independent of the known ones. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Regularly decreasing weights and the topological subspace problem
Authors: Taskinen Jari
Published: June 2005

We improve the example of a weighted space of analytic functions given in [8]: we replace the discontinuous weights of [8] by continuous ones and the disconnected domain by a connected one. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stochastic differential equations with fractal noise
Authors: Zähle M.
Published: June 2005

Stochastic differential equations in ℝn with random coefficients are considered where one continuous driving process admits a generalized quadratic variation process. The latter and the other driving processes are assumed to possess sample paths in the fractional Sobolev space Wβ2 for some β > 1/2. The stochastic integrals are determined as anticipating forward integrals. A pathwise solution procedure is developed which combines the stochastic Itô calculus with fractional calculus via norm estimates of associated integral operators in Wα 2 for 0 < α < 1. Linear equations are considered as a special case. This approach leads to fast computer algorithms basing on Picard's iteration method. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nitroxide‐Mediated Controlled/Living Free Radical Copolymerization of Styrene and Divinylbenzene in Aqueous Miniemulsion
Authors: Zetterlund Per B. , Alam Md. Nur , Minami Hideto , Okubo Masayoshi
Published: June 2005

Summary: The nitroxide‐mediated controlled/living free radical copolymerization of styrene and divinylbenzene using a polystyrene‐TEMPO macroinitiator in aqueous miniemulsion and in bulk have been investigated. The crosslink densities were estimated based on the content of pendant vinyl groups as determined by 1H NMR. Considerably lower crosslink densities were revealed in the miniemulsion than in the corresponding bulk system. The rate of polymerization in the miniemulsion increased with decreasing particle size, and was significantly higher than in bulk.

Crosslink density for the TEMPO‐mediated free radical copolymerization of S(1) and DVB(2) (f = 0.99, f = 0.01) at 125 °C in bulk (□) and in miniemulsions with dn = 585 nm (○) and 53.3 nm (•).

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Crosslink density for the TEMPO‐mediated free radical copolymerization of S(1) and DVB(2) (f = 0.99, f = 0.01) at 125 °C in bulk (□) and in miniemulsions with dn = 585 nm (○) and 53.3 nm (•).
Bioaffinitive and Nanosized Polymeric Micelles Based on a Reactive Block Copolymer
Authors: Hu Yong‐Chen , Pan Cai‐Yuan
Published: June 2005

Summary: Bio‐affinitive, nanosized polymeric micelles with glucosamine in their corona have a specific interaction with Concanavalin A. They are prepared by a substitution reaction of p‐nitrophenol groups in the poly(p‐nitrophenyl acrylate) (PNPA) corona of stable micelles with glucosamine. The nanosized, stable, and reactive micelles are formed by self‐assembly of the diblock copolymer, poly(p‐nitrophenyl acrylate)‐block‐polystyrene (PNPA‐b‐PSt) in nitromethane, followed by a shell cross‐linking reaction. This method may be useful in the preparation of targeted drugs.

A schematic of the formation of stable glucosamine‐carrying micelles from the diblock copolymer, PNPA‐b‐PSt.

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A schematic of the formation of stable glucosamine‐carrying micelles from the diblock copolymer, PNPA‐b‐PSt.
Highly Thermal Stable Main‐Chain Nonlinear Optical Polyimide Based on Two‐Dimensional Carbazole Chromophores
Authors: Tsai Hsieh‐Chih , Kuo Wen‐Jang , Hsiue Ging‐Ho
Published: June 2005

Summary: A new NLO‐active lambda‐shaped main‐chain polyimide that comprises a two‐dimensional carbazole chromophore was synthesized. This polyimide exhibits high thermal and temporal stability. It can endure temperatures of up to 240 °C for a transient time and maintain a large SH signal at 100 °C for a long time because embedding the two‐dimensional chromophores into the polymer backbone effectively suppresses the randomization of the oriented dipole at high temperatures.

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Defined Picogram Dose Inclusion and Release of Macromolecules using Polyelectrolyte Microcapsules
Authors: Déjugnat Christophe , Haložan David , Sukhorukov Gleb B.
Published: June 2005

Summary: Reversible pH‐induced swelling of (PAH/PSS) polyelectrolyte microcapsules is accompanied by increased porosity, making them permeable to poly(acrylic acid) (PAA) at pH values higher than 11.2. This pH‐switchable permeability was used to encapsulate the polyanion in alkaline conditions. Relationship between starting PAA concentration in solution and amount finally being encapsulated has been established and can be used further as calibration curve. A desired amount of encapsulated polymer in the picogram range per capsule can be achieved. The loaded capsules were then used as microreactors by forming a complex between the PAA and Ca2+ ions.

General scheme for pH‐induced encapsulation of (PAA) in alkali condition by switching their permeability.

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General scheme for pH‐induced encapsulation of (PAA) in alkali condition by switching their permeability.
Surface Plasmon Resonance Spectroscopy as a Tool to Study Polyplex‐Glycoaminoglycan Interactions
Authors: Dubruel Peter , Urtti Arto , Schacht Etienne
Published: June 2005

Summary: This article reports the application of surface plasmon resonance (SPR) to monitor the interaction between polymer‐DNA complexes and glycoaminoglycans (GAG). The GAG selected was hyaluronic acid (HA). First a HA derivative containing a disulfide linkage was synthesized, enabling chemisorption onto a gold surface. Next, the interaction between different complexes (prepared using PEI or PDMAEMA) and HA was studied using SPR. This study clearly indicates that GAG‐polyplex interactions depend on the type of polymer selected and on the charge ratio of the polyplexes prepared.

The derivative developed opens up new perspectives in the field of nonviral gene delivery.

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The derivative developed opens up new perspectives in the field of nonviral gene delivery.
Nanostructured Thermosetting Systems from Epoxidized Styrene Butadiene Block Copolymers
Authors: Serrano Elena , Martin M. Dolores , Tercjak Agnieszka , Pomposo Jose A. , Mecerreyes David , Mondragon Iñaki
Published: June 2005

Summary: Nanostructured thermosetting materials were prepared by modification of an epoxy resin with 30 wt.‐% epoxidized polystyrene‐block‐polybutadiene copolymer (PS‐b‐PepB). The copolymer self‐assembles into a well‐defined hexagonal nanoordered structure, of around 30‐nm diameter, thus establishing its use as structure‐directing agent to generate nanostructured thermosetting materials. The study confirms pathways towards tailoring interactions between thermosetting matrices and immiscible block copolymers by using the concept of functionalization to build nanostructured polymer matrices.

Structure of diglycidyl ether of bisphenol‐A/4,4′‐methylenebis(3‐chloro 2,6‐diethylaniline) cured blend containing 30 wt.‐% PS‐b‐PepB61 block copolymer.

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Structure of diglycidyl ether of bisphenol‐A/4,4′‐methylenebis(3‐chloro 2,6‐diethylaniline) cured blend containing 30 wt.‐% PS‐b‐PepB61 block copolymer.
A New Model and Measurement Technique for Dynamic Shrinkage during Photopolymerization of Multi‐Acrylates
Authors: Neo Wee Koon , Chan‐Park Mary B.
Published: June 2005

Summary: A novel experimental set‐up has been devised to measure simultaneously, in real time, the conversion and shrinkage of multi‐acrylates during photopolymerization. The data show that the current practice of assigning the excess volume entirely as excess free volume is inappropriate as this leads to an increasing fractional free volume with conversion. We propose to partition the excess volume into free and occupied volume components. The new model produces satisfactory results.

Experimental set‐up for the simultaneous collection of shrinkage and conversion data.

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Experimental set‐up for the simultaneous collection of shrinkage and conversion data.
New π‐Conjugated Polymers Containing 1,3,5‐Triazine Units in the Main Chain: Synthesis and Optical and Electrochemical Properties of the Polymers
Authors: Ren Shijie , Fang Qiang , Lei Yi , Fu Haitao , Chen Xiaoyao , Du Junping , Cao Amin
Published: June 2005

Summary: Three new soluble π‐conjugated polymers containing 1,3,5‐triazine units in the main chain, Pa–Pc, were synthesized. The polymers showed optical properties in solution that were mainly dependant on the properties of the substituting R groups, on the triazine ring. Hence, Pa and Pb (R = H and OCH3, respectively) showed blue photoluminescent (PL) emission with high quantum yields (QY) even in polar solvents, whereas Pc (R = N,N‐dimethylamino) gave green‐blue PL emission with very low QY. The PL spectra of the polymers in solution were concentration and polarity dependent, which suggested the formation of an exciplex.

The three new soluble π‐conjugated polymers containing 1,3,5‐triazine units in the main chain synthesized here.

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The three new soluble π‐conjugated polymers containing 1,3,5‐triazine units in the main chain synthesized here.
A Catalytic Approach to Functional Poly(1,4‐ketone)s Bearing Pendant Monosaccharide Fragments
Authors: Malinova Violeta , Rieger Bernhard
Published: June 2005

Summary: Novel alternating polyketone‐based polymers bearing pendant saccharide units that are accessible by polymerization catalysis are presented. The materials were synthesized by polymerization of carbon monoxide and α‐olefins containing protected glucose or N‐acetyl glucosamine residues. The dicationic PdII bis(phoshine) complex [Pd(dppp)(NCCH3)2](BF4)2 was used as a catalyst precursor. An O‐deacetylation of the copolymers afforded materials with amphiphilic character.

Structure of the poly(1,4‐ketone) copolymers synthesized here.

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Structure of the poly(1,4‐ketone) copolymers synthesized here.
A Versatile and Efficient Hydrosilylation Route to Functionalized Polyferrocenylsilanes
Authors: Hilf Stefan , Cyr Paul W. , Rider David A. , Manners Ian , Ishida Tamao , Chujo Yoshiki
Published: June 2005

Summary: The synthesis of a series of polyferrocenylsilanes (PFSs) containing CC functionalities in the side‐group structure and their subsequent derivatization by hydrosilylation chemistry are described. Hydrosilylation is shown to be an effective postpolymerization functionalization method, particularly in the case of poly(ferrocenylmethylvinylsilane), which can be prepared by photolytic anionic ring‐opening polymerization of the corresponding ferrocenophane monomer.

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Changes in quadriceps twitch tension in response to resistance training in healthy sedentary subjects
Authors: Vivodtzev Isabelle , Wuyam Bernard , Flore Patrice , Lévy Patrick
Published: June 2005

Magnetic stimulation of the femoral nerve has been shown to evoke maximal quadriceps twitch contraction (TwQmax). Its measurement as a nonvolitional index of muscle strength has been proposed as a means to follow the disability of patients with neuromuscular disorders or peripheral muscle weakness. The aim of the present study was to investigate TwQmax sensitivity to interventions known to develop peripheral muscle strength. We thus measured changes in TwQmax after a short‐duration resistance training program, examining its reproducibility and comparing its changes with other indices of muscle strength, such as maximal voluntary contraction (MVC) and one‐repetition maximum (1‐RM). In 23 subjects, TwQmaxwas measured on two occasions. High within‐ and between‐session intraclass coefficients of correlation were observed (r > 0.99). Within‐session and between‐session differences in TwQmaxwere low (2.2 ± 1% and 5.4 ± 2%, respectively). Eight subjects subsequently participated in a resistance training program of the knee extensors, 3 days per week for 8 weeks. TwQmax and 1‐RM increased significantly after training (10.9 ± 3.7 vs. 12.3 ± 4.4 kg, P < 0.04; and 45 ± 13 vs. 55 ± 12 kg, P < 0.001, respectively), whereas the MVC increase did not reach significance (41.9 ± 16 kg vs. 42.3 ± 15 kg, P = 0.25). Responses to magnetic stimulation of the femoral nerve are highly reproducible and sensitive enough to detect improvement in muscle contractile mechanisms after resistance training in healthy subjects. Patient cooperation is not required, which may be an advantage in clinical situations. Muscle Nerve, 2005
Electrical impedance myography in the detection of radiculopathy
Authors: Rutkove Seward B. , Esper Gregory J. , Lee Kyungmouk S. , Aaron Ronald , Shiffman Carl A.
Published: June 2005

Electrical impedance myography (EIM) is a new bioimpedance‐based technique for neuromuscular disease assessment. Past work has focused on EIM in the evaluation of diffuse diseases (such as myopathy). In this study, the method's most basic form, linear‐EIM, was used for the assessment of restricted radiculopathic disease. Ten normal subjects and 10 patients with unilateral cervical or lumbosacral radiculopathy, diagnosed by electromyography and clinical criteria, were enrolled. Linear‐EIM was performed bilaterally on all individuals, and comparisons with the major outcome variable, θavg, were made. In normal subjects, side‐to‐side differences in θavg averaged 0.64% and were no greater than 15.9% in magnitude. In the 10 patients with radiculopathy, θavgwas consistently lower in the affected extremity, with a mean side‐to‐side difference of 15.3%, but ranging as low as 72.3%; there was a tendency for muscles with more prominent chronic neurogenic change to show greater relative reductions in θavg. These findings support the potential utility of EIM in assessment of localized neuromuscular disease. Muscle Nerve, 2005
Three‐dimensional topography of the motor endplates of the rat gastrocnemius muscle
Authors: Prodanov Dimiter , Thil Marie‐Anne , Marani Enrico , Delbeke Jean , Holsheimer Jan
Published: June 2005

Spatial distribution of motor endplates affects the shape of the electrical activity recorded from muscle. In order to provide information for realistic models of action potential propagation within muscles, we assembled three‐dimensional maps of the motor endplates of the rat medial gastrocnemius (MGM) and lateral gastrocnemius (MGL) muscles. The maps were assembled from histological cross sections stained for acetylcholinesterase activity. Within MGL, the motor endplates formed three columns along its longitudinal axis. Within MGM, the motor endplates were arranged in a leaf‐like body that shifted obliquely from proximal to distal. As inferred from the proximo‐distal distribution of the cross‐sectional projection area, the majority of the motor endplates were concentrated in the middle of MGL and in the distal third of MGM. Regions of maximal motor endplate concentration are considered most suitable for injections of neuroactive substances, such as neuronal tracers. The assembled maps of the gastrocnemius muscles can be used as guides for such injections within the motor endplate zones. Muscle Nerve, 2005
Project scheduling under competition
Authors: Averbakh Igor , Lebedev Vasilij
Published: June 2005

We introduce and investigate the problem of scheduling activities of a project by a firm that competes with another firm (the competitor) that has to perform the same project. The profit that the firm gets from each activity depends on whether the firm finishes the activity before or after its competitor. The objective is to maximize the guaranteed (worst‐case) profit. We assume that both the firm and the competitor can perform only one activity at a time. We perform a detailed complexity analysis of the problem, and consider problems with and without precedence constraints, with and without delay of the competitor, with general and equal processing times of activities. For polynomially solvable cases (which include, for example, all the considered problems without delay of the competitor), we present easily implementable and intuitive rules that allow us to obtain optimal schedules in linear or almost linear time. For some NP‐hard cases, we present pseudopolynomial algorithms and fast heuristics with worst‐case approximation guarantees. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2005.
A superfast solver for real symmetric Toeplitz systems using real trigonometric transformations
Authors: Codevico G. , Heinig G. , Van Barel M.
Published: June 2005

A new superfast O(n log2 n) complexity direct solver for real symmetric Toeplitz systems is presented. The algorithm is based on 1. the reduction to symmetric right‐hand sides, 2. a polynomial interpretation in terms of Chebyshev polynomials, 3. an inversion formula involving real trigonometric transformations and 4. an interpretation of the equations as a tangential interpolation problem. The tangential interpolation problem is solved via a divide and conquer strategy and fast DCT. Copyright © 2005 John Wiley & Sons, Ltd.
Matrix recursive expressions of the DFT of even and odd complex sequences
Authors: Notarnicola Filippo
Published: June 2005

The discrete Fourier transform of even complex sequences involves, in matrix formulation, a cosine matrix and, in the same way, the discrete Fourier transform of odd complex sequences is related with a sine matrix. Using structural characteristics of the two matrices, whose order is half the length of the symmetric input data, some recursive expressions of them will be constructed.

Unlike the previous classical forms of the discrete Fourier transform of an even or odd real vector, the recursive terms in the matrix expressions derived here only involve the same cosine and sine matrices, with halved order. That is, it is shown that, as for the FFT of a general complex sequence, a divide and conquer approach can also be used to compute the DFT of even or odd sequences. The recursion is closed in the family of the sine and cosine matrices used to describe the DFT of even and odd sequences and no other kind of sine or cosine based matrices are required in recursive terms.

Although the obtained results give a new theoretical view on the problem of computing the DFT of even and odd complex sequences, these are not of immediate practical use since the computational cost is higher than other currently employed algorithms. Copyright © 2005 John Wiley & Sons, Ltd.
Central diabetes insipidus: Is it Langerhans cell histiocytosis of the pituitary stalk? A diagnostic pitfall
Authors: Prosch Helmut , Grois Nicole , Bökkerink Jos , Prayer Daniela , Leuschner Ivo , Minkov Milen , Gadner Helmut
Published: June 2005

Central diabetes insipidus (CDI) is a rare disorder that may be caused by a variety of diseases. In pediatric and adolescent patients the most common causes for CDI are Langerhans cell histiocytosis (LCH) and germinoma. To avoid a potentially hazardous biopsy of the hypothalamic pituitary region it is recommended to evaluate patients with CDI carefully to identify potential extracranial lesions. Since LCH is the most common systemic disease that may cause CDI, special focus is paid to the identification of LCH lesions. We report on a 9½ year old girl who presented with central diabetes insipidus and a thickening of the pituitary stalk on magnetic resonance imaging. Diagnostic workup revealed a history of recurrent ear infections and a compressed 6th thoracic vertebral body on radiographs. Based on these findings LCH was anticipated. Upon growth of the pituitary stalk lesion the patient was treated with LCH standard chemotherapy. After an initial shrinkage of the lesion, a further growth of the pituitary stalk lesion was observed and the tumor was resected. Histopathology revealed germinoma. This case underscores the importance of a istopathologically proven diagnosis in patients with HPR tumors before the initiation of a specific therapy, even if the clinical findings are highly suggestive. © 2005 Wiley‐Liss, Inc.
Synthesis, properties and pyrolysis of siloxane‐ and imide‐modified epoxy resin cured with siloxane‐containing dianhydride
Authors: Li Hsun‐Tien , Chuang Hsun‐Ren , Wang Ming‐Wei , Lin Mu‐Shih
Published: June 2005

Hydrosilylation of nadic anhydride with tetramethyl disiloxane yielded 5,5′‐(1,1,3,3‐tetramethyl disiloxane‐1,3‐diyl)‐bis‐norborane‐2,3‐dicarboxylic anhydride (I), which further reacted with 4‐aminophenol to give N,N′‐bis(4‐hydroxyphenyl)‐5,5′‐bis‐(1,1,3,3‐tetramethyl disiloxane‐1,3‐diyl)‐bis‐norborane‐2,3‐dicarboximide (II). Epoxidation of II with excess epichlorohydrin formed a siloxane‐ and imide‐modified epoxy oligomer (ie diglycidyl ether of N,N′‐bis(4‐hydroxyphenyl)‐5,5′‐bis(1,1,3,3‐tetramethyl disiloxane‐1,3‐diyl)‐bis‐norborane‐2,3‐dicarboximide) (III). Equivalent ratios of III/I of 1/1 and 1/0.8 were prepared and cured to produce crosslinked materials. Thermal mechanical and dynamic mechanical properties were investigated by TMA and DMA, respectively. It was noted that each of these two materials showed a glass transition temperature (Tg) higher than 160 °C with moderate moduli. The thermal degradation kinetics was studied with dynamic thermogravimetric analysis (TGA) and the estimated apparent activation energies were 111.4 kJ mol−1 (in N2), 117.1 kJ mol−1 (in air) for III/I = 1/0.8, and 149.2 kJ mol−1 (in N2), 147.6 kJ mol−1 (in air) for III/I = 1/1. The white flaky residue of the TGA char was confirmed to be silicon dioxide, which formed a barrier at the surface of the polymer matrix and, in part, accounted for the unique heat resistance of this material. Copyright © 2005 Society of Chemical Industry
UV‐Vis spectroscopic study of the hydrophilic and solvatochromic 4‐[2,6‐diphenyl‐4‐(pyridin‐4‐yl)pyridinium‐1‐yl]‐2,6‐bis(pyridin‐3‐yl)phenolate betaine dye in aqueous tetra‐n‐butylammonium bromide
Authors: Herodes Koit , Leito Ivo , Koppel Juta , Reichardt Christian , Koppel Ilmar A.
Published: June 2005

The solvent influence on the recently synthesized hydrophilic and negatively solvatochromic 4‐[2,6‐diphenyl‐4‐(pyridin‐4‐yl)pyridinium‐1‐yl]‐2,6‐bis(pyridin‐3‐yl)phenolate betaine dye [ET(8) dye] dissolved in binary water–tetra‐n‐butylammonium bromide mixtures was studied by UV–Vis spectroscopy and compared with analogous measurements of the standard ET(30) betaine dye [2,6‐diphenyl‐4‐(2,4,6‐triphenylpyridinium‐1‐yl)phenolate]. A preferential solvation model was applied to the data obtained. The ET(8) betaine dye can be applied for the determination of ET(30) values for aqueous media. However, the nonlinear nature of the relationship has to be taken into account if accurate results are desired. Copyright © 2005 John Wiley & Sons, Ltd.
Effect of hydrophobic side‐chains on the solvation of imidazolium salts
Authors: Headley Allan D. , Kotti S. R. S. Saibabu , Nam Jaewook , Li Kunyu
Published: June 2005

The chemical shifts of the aromatic hydrogens of 12 symmetrical imidazolium salts were determined in different deuterated solvents. Based on the magnitude of the chemical shift change for the hydrogens of the imidazolium ion in the various solvents, relationships were developed to determine the relative solute/solvent interactions for these compounds. Owing to different degrees of interactions involving the aromatic hydrogens of the imidazolium cations and anions, there is a variation in the interaction of the hydrogens with the solvent molecules. The intimate interaction that exists between the hydrogens of the imidazolium cation and the BF anion results in the BF salts being less solvated compared with salts containing BF and SbF anions. For imidazolium salts that contain C2H5, C4H9 and C8H17 side‐chains bonded in the 1 and 3 positions, the interaction between H2 and the solvents was observed to be greater than for imidazolium salts with C16H33 substituents. On the other hand, for imidazolium salts that have C16H33 substituents the interaction between H2 and the solvents is similar to that for H4 and H5. Copyright © 2005 John Wiley & Sons, Ltd.
Synthesis, photophysics, structure‐tunable photoluminescence, and electrochemical properties of soluble poly(p‐phenylenevinylene)‐based polymers with adjacent 1,3,4‐oxadiazoles in the backbone
Authors: Mikroyannidis John A. , Hlídková Helena , Výprachtický Drahomír , Cimrová Věra
Published: June 2005

Three new poly(p‐phenylenevinylene)‐based polymers containing two 1,3,4‐oxadiazole moieties in the main chain per repeat unit were synthesized by Heck coupling. A single, double, or triple bond was introduced between the oxadiazoles to provide a means for modifying the polymer properties. The polymers were readily soluble in common organic solvents and showed Tg values lower than 50 °C. The color of the emissive light in both the solid state and the solution could be tuned by a change in the nature of the bond between the oxadiazole rings. The polymers emitted ultraviolet‐green light in solution with a photoluminescence (PL) emission maximum at 345–483 nm and blue‐green light at 458–542 nm in thin films. The PL quantum yields in solution were 0.36–0.43. The electrochemical properties are affected by the nature of the bond between the oxadiazoles as well. In polymers with a single bond between the oxadiazoles, a lower ionization potential was observed than in polymers with a double or triple bond. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3079–3090, 2005
Synthesis, characterization, and metal complexes of polyacetylenes with pendant 2,2′‐bipyridyl groups
Authors: Vicente José , Gil‐Rubio Juan , Barquero Natalia
Published: June 2005

5‐Ethynyl‐2,2′‐bipyridine (1; bpyC≡CH) polymerized in the presence of catalytic amounts of [RhF(COD)(PPh3)] or [Rh(μ‐OH)(COD)]2 (COD = 1,5‐cyclooctadiene) in 74–91% yields. In contrast, [Rh(μ‐X)(NBD)]2 (X = Cl or OMe; NBD = norbornadiene) did not catalyze the polymerization of 1 or gave low yields of the polymer. The obtained polymer, poly(5‐ethynyl‐2,2′‐bipyridine) [2; (bpyCCH)n], was highly stereoregular with a predominant cis–transoidal geometry. Random copolyacetylenes containing the 2,2′‐bipyridyl group with improved solubility in organic solvents were obtained by the treatment of a mixture of 1 and phenylacetylene (3) or 1‐ethynyl‐4‐n‐pentyl‐benzene with catalytic amounts of [RhF(COD)(PPh3)]. A block copolymer of 1 and 3 was prepared by the addition of 1 to a poly(phenylacetylene) containing a living end. The reaction of 2 with [Mo(CO)6] produced an insoluble polymer containing [Mo(CO)4(bpy)] groups, whereas with [RuCl2(bpy)2] or [Ru(bpy)2(CH3COCH3)2](CF3SO3)2, it gave soluble metal–polymer complexes containing [Ru(bpy)3]2+ groups. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43:3167–3177, 2005
Surface segregation in polymer blends and interpolymer complexes with increasing hydrogen bonding interactions
Authors: Liu Shiyong , Chan Chi‐Ming , Weng Lu‐Tao , Jiang Ming
Published: June 2005

The evolution of surface composition in polymer blends and interpolymer complexes was studied using X‐ray photoelectron spectroscopy (XPS) and Time‐of‐Flight secondary ion mass spectroscopy (ToF‐SIMS). For immiscible and miscible poly(styrene‐co‐4‐vinyl phenol)/poly(styrene‐co‐4‐vinyl pyridine) (STVPh/STVPy) blends, surface enrichment by the lower surface energy component STVPh was always observed. Increasing VPh contents in STVPh from 0 to 16 mol % spans the transition from immiscible to miscible blends; the differences in surface free energies between STVPh and STVPy decreased, but surface enrichment of STVPh continued to increase. This is due to the strong hydrogen bonded self‐association of STVPh, which dominates over the immiscibility to miscibility transition in controlling the surface composition. In the immiscible and miscible blends, decreasing the molecular weights of STVPy, which decreased the surface free energy of STVPy, systematically reduced surface enrichment by STVPh. For STVPh/STVPy complexes formed at VPh contents higher than 21 mol %, surface enrichment of STVPh is barely detectable. STVPh and STVPy form a new supramolecular species. Interpolymer complexation is now the decisive factor controlling the surface composition, dominating over the surface free energy differences; the effect of STVPy molecular weight variation on the surface composition is also negligible for the interpolymer complexes. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1924–1930, 2005
Isothermal crystallization kinetics of PP in PP/Mg(OH)2 composites
Authors: Yin Jun , Wang Shaohui , Zhang Yong , Zhang Yinxi
Published: June 2005

The crystallization and melting behavior of PP/Mg(OH)2 composites was investigated, and the crystallization kinetic parameters and thermal characteristics were investigated according to the Avrami method. Optical polarizing microscope (POM) analysis suggested that the presence of Mg(OH)2 particles gave rise to an increase in the number of nuclei and a decrease in PP spherulitic size. The Avrami exponent n of the PP and composites increased with increasing crystallization temperature, and markedly deceased with the addition of low Mg(OH)2 content. A significant increase in crystallization kinetic constant, and a decrease in crystallization half time of PP were observed in the presence of Mg(OH)2 particles, indicating a heterogeneous nucleating effect of Mg(OH)2 upon crystallization of PP. The melting temperature and equilibrium melting temperature of PP in the composites decreased with increasing the Mg(OH)2 content, which is directly related to the size of the PP crystals. The difference of PP melting enthalpies in the PP and composites demonstrated that the presence of Mg(OH)2 can effectively enhance the crystalline of PP. The crystallization thermodynamics of PP and composites were studied according to the Hoffman theory. Surface free energy of PP chain folding for crystallization of PP/Mg(OH)2 composites was lower than that of PP, confirming the heterogeneous nucleation effect of Mg(OH)2. However, the evaluation of the nucleation activation energy of PP suggested the presence of a large amount of Mg(OH)2 particles in the PP matrix reduced the mobility of PP segments and restricted the development of PP nucleation. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1914–1923, 2005
Structure and properties of the δ‐form and mesophase of syndiotactic polystyrene membranes prepared from different organic solvents
Authors: Sivakumar Muthusamy , Mahesh K.P.O. , Yamamoto Yusuke , Yoshimizu Hiroaki , Tsujita Yoshiharu
Published: June 2005

Syndiotactic polystyrene (sPS) membranes were prepared with different organic solvent systems and compared to get the information about the δ‐form complexing behavior of sPS. Further, the guest molecules included in the clathrate δ form of sPS are removed by stepwise extraction method. The conformational changes during the TTGG helical formation of sPS/organic solvent systems have been identified by FTIR spectroscopy, and it was concluded that the TTGG helices were constructed in regular sequences, which depends on the nature of the respective solvents. The TTGG content in the mesophase is found to be increased by removing the guest molecules. The structural changes of sPS/organic solvent systems have been characterized by WAXD analysis. Moreover, the different clathrate structures were found and showed the different crystalline reflections in the WAXD profiles, which are significantly changed with the kind of guest solvent included in sPS. The content of solvents in the clathrated sPS and the desorption temperatures were determined by thermal analysis. The resulted mesophase of sPS membrane contains the nanoporous molecular cavities that depend on the size of the guest molecule. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1873–1880, 2005