bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical and surface properties of polyurethane/fluorinated multi‐walled carbon nanotubes composites
Authors: Deng Jinni , Cao Jing , Li Jiehua , Tan Hong , Zhang Qin , Fu Qiang
Published: February 2008

To improve the mechanical and surface properties of poly(etherurethane) (PEU), multi‐walled carbon nanotubes (MWCNTs) were surface grafted by 3,3,4,4, 5,5,6,6,7,7,8,8,8‐tridecafluoro‐1‐octanol (TDFOL) (MWCNT‐TDFOL) and used as reinforcing agent for PEU. Fourier‐transform infrared spectroscopy revealed the successful grafting of MWCNTs. PEU filled with MWCNT‐TDFOL could be well dispersed in tetrahydrofuran solution, and tensile stress–strain results and dynamic mechanical analysis showed a remarkable increase in mechanical properties of PEU by adding a small amount of MWCNT‐TDFOL. Contact angle testing displayed a limited improvement (just 9°) in the hydrophobicity of PEU surface by solution blending with MWCNT‐TDFOL. However, a large improvement of surface hydrophobicity was observed by directly depositing MWCNT‐TDFOL powder on PEU surface, and the water contact angle was increased from 80° to 138°. Our work demonstrated a new way for the modification of carbon nanotubes and for the property improvement of PEU. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Modeling of a fluidized bed propylene polymerization reactor operated in condensed mode
Authors: Utikar Ranjeet P. , Harshe Yogesh M. , Mehra Anurag , Ranade Vivek V.
Published: February 2008

The gas‐phase polymerization of propylene is one of the most widely accepted and commercially used processes for the manufacture of polypropylene (PP). Because of the highly exothermic nature of polymerization reactions, temperature runaway and subsequent polymer melting and agglomeration may occur, and the reactor has to be operated in a small operating window for safety. The addition of liquid monomer for heat removal (condensed mode) broadens the operating window and can substantially increase (by 50–100%) the capacity of given reactor hardware. This article describes the extension of a comprehensive mathematical model for the simulation of fluidized bed PP reactors to include the condensed mode of operations. The model is used to determine the influence of the operating parameters on the polymer properties and particle size distribution. The model is also used to determine the effects of two active sites and the reaction kinetics on macroscopic variables. The developed framework is useful for simulating multimonomer, multisite Ziegler–Natta‐type olefin fluidized bed polymerization reactors operated under condensed mode. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
New toughened polypropylene/organophilic montmorillonite nanocomposites
Authors: Li Peiyao , Song Guojun , Yin Lanlan , Wang Li , Ma Guiping
Published: February 2008

A new toughened polypropylene (PP)/organophilic montmorillonite (OMMT) nanocomposite was obtained by melt intercalation extrusion in a twin‐screw extruder without any compatibilizer. The nanocomposites were characterized by transmission electron microscopy (TEM) observation, melt flow rate (MFR) testing, mechanical properties measurement, melting and crystallization behaviors, and thermal stability determination. TEM images revealed the existence of intercalated OMMT layers dispersed throughout the PP matrix. A clear reduction in MFR was observed as the OMMT content increased. The yield strength, elongation at yield, and initial modulus of the PP/OMMT nanocomposites increased slightly as the result of the reinforcement of the OMMT nanofiller. The ultimate value of notched impact strength of the nanocomposites was over twofold that of neat PP after incorporation with 4 wt % OMMT; meanwhile, the heat deflection temperature values showed that the thermal stability increased a little. This is a new approach for preparation for the production of a toughened PP material with a high thermal stability and rigidity. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Morphology of polyvinylidenefluoride and the copolymer of tetrafluoroethylene with ethylene using thermomechanical analysis
Authors: Olkhov Yu. A. , Allayarov S. R. , Konovalova T. A. , Kispert L. D. , Nikles D. E.
Published: February 2008

The morphology of polyvinylidenefluoride (PVDF) and the copolymer of tetrafluoroethylene with ethylene (CTE) were investigated by thermomechanical analysis. Both granules and highly dispersed powders of the polymers have similar morphology. Polymer granules contain amorphous and crystalline regions. The morphology of the polymer powders were determined under two analytical conditions: coaxial, when the vectors of polymer loading and vector of compression pressure are in the same plane, or when they are perpendicular to each other. One amorphous and two crystal blocks were found at coaxial orientations of the vectors. Thermomechanical analysis showed that the polymers had a completely amorphous diblock morphology at the perpendicular orientation of the vectors. Parameters that characterize a degree of interchain interaction, such as coefficients of thermal expansion, free volume, and temperatures of polymer transformation into the glassy, high‐elastic, or flow‐viscous state were determined. PVDF and CTE have similar topographic composition, but different molecular mass and temperatures of phase transitions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Blends of poly(L‐lactic acid) with poly(ω‐pentadecalactone) synthesized by enzyme‐catalyzed polymerization
Authors: Nakane Koji , Tamaki Chiharu , Hata Yoshihiro , Ogihara Takashi , Ogata Nobuo
Published: February 2008

Poly(ω‐pentadecalactone) (PPDL) was synthesized by enzyme‐catalyzed polymerization. The molecular weight of the PPDL was about 35,000. Opaque poly(L‐lactic acid) (PLLA)/PPDL blend films were created by the solvent casting technique. The addition of PPDL led to PLLA crystallization. Furthermore, the addition of PPDL with PLLA increased both the Young's modulus [pure PLLA : 0.67 GPa, PLLA/PPDL (70/30 wt %) : 1.01 GPa] and the PLLA glass transition temperature. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Mechanical properties of polylactide after repeated cleanings
Authors: Karst David , Hain Michelle , Yang Yiqi
Published: February 2008

The ability of polylactide (PLA) to retain its mechanical properties after repeated cleanings at various pH levels, washing temperatures, and drying conditions has been studied. One of the problems with PLA is its poor resistance to hydrolysis, especially under alkaline conditions. In this study, PLA fabrics were sent through 50 cleaning cycles with different pH levels (8 or 10), washing temperatures (35 or 55°C), and drying conditions (air dry at 21°C/65% relative humidity or tumble dry at 50 or 70°C). The retention percentages of the breaking tenacity, breaking elongation, and modulus of the PLA yarns were measured after every 10 cleaning cycles. A pH of 8 gave greater breaking tenacity, breaking elongation, and modulus retention than pH 10. Washing PLA at 35°C and air drying it at 21°C resulted in greater modulus retention than washing and drying at higher temperatures. Hydrolysis of the polymer was the main cause of the loss in mechanical properties. Equations were developed to predict the retention percentage of the breaking tenacity, breaking elongation, and modulus based on the pH, number of cleaning cycles, and washing and drying temperatures. Recommendations for appropriate conditions for the cleaning of PLA fabrics that result in greater mechanical property retention are given. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Ontology‐based speech act identification in a bilingual dialog system using partial pattern trees
Authors: Yeh Jui‐Feng , Wu Chung‐Hsien , Chen Ming‐Jun
Published: February 2008

This article presents a bilingual ontology‐based dialog system with multiple services. An ontology‐alignment algorithm is proposed to integrate ontologies of different languages for cross‐language applications. A domain‐specific ontology is further extracted from the bilingual ontology using an island‐driven algorithm and a domain corpus. This study extracts the semantic words/concepts using latent semantic analysis (LSA). Based on the extracted semantic words and the domain ontology, a partial pattern tree is constructed to model the speech act of a spoken utterance. The partial pattern tree is used to deal with the ill‐formed sentence problem in a spoken‐dialog system. Concept expansion based on domain ontology is also adopted to improve system performance. For performance evaluation, a medical dialog system with multiple services, including registration information, clinic information, and FAQ information, is implemented. Four performance measures were used separately for evaluation. The speech act identification rate was 86.2%. A task success rate of 77% was obtained. The contextual appropriateness of the system response was 78.5%. Finally, the rate for correct FAQ retrieval was 82%, an improvement of 15% over the keyword‐based vector‐space model. The results show the proposed ontology‐based speech‐act identification is effective for dialog management.
Hjørland's critique of bates' work on defining information
Authors: Bates Marcia J.
Published: February 2008

In a recent article, Birger Hjørland (2007) critiqued the author's efforts in defining and conceptualizing information as a core concept in information science (Bates, 2005, 2006). It is argued that Hjørland has seriously misrepresented and confused the actual line of argument in those articles. Specifics of that case are presented, and the reader is urged to return to the original Bates articles to understand her claims. In those articles, Bates attempted to develop a broad conception of information, as well as a number of subtypes of information, for use in the field of information science. The development of information was related to evolutionary processes, with emergence as a significant theme.
Zum Einfluss der Nietkopfabrostung auf die Nietvorspannung und Dauerhaftigkeit alter Stahlkonstruktionen
Authors: Feldmann Markus , Heinemeyer Christoph , Hinrichs Hauke
Published: February 2008

Nicht selten sind bei genieteten Brücken die Niete selbst markante Punkte des Korrosionsangriffs. So sind die Korrosionserscheinungen besonders an den Köpfen der Niete in Form von Abrostungen etc. zu beobachten. Dies wirft die Frage auf, ab wann und inwieweit die Nietvorspannung durch die Materialabtragung abgemindert wird, so dass mit einer Beeinträchtigung des Trag‐ und Ermüdungsverhaltens zu rechnen ist. In dem folgenden Beitrag wird der Vorspann‐ und Klemmzustand von Nietungen in Abhängigkeit von einem durch Korrosion reduzierten Restquerschnitt des Nietkopfs vorgestellt. Dabei werden in experimentellen Untersuchungen, die durch numerische Untersuchungen ergänzt werden, die Abrostungen durch Fräsungen am Nietkopf simuliert. Durch weitere Versuche gelingt es, eine Prognose der Ermüdungsfestigkeiten in Abhängigkeit des durch die Nietkopfabrostung verursachten Vorspannungsabfalls und der dadurch bedingten verstärkten Spannungsspitzen im Blech abzugeben.
Sanierung und Verstärkung von Gründungsbauteilen
Authors: Dehn Frank , Gebhardt Matthias , Pollnow Elke
Published: February 2008

Die Bedeutung des Bauens im Bestand wird in den nächsten Jahren, gemessen am Gesamtbauvolumen, weiter zunehmen. Insbesondere steht die öffentliche Hand vor der großen Herausforderung, eine Vielzahl historischer, denkmalgeschützter Bauten vor weiterem Verfall zu bewahren und möglichst einer Nutzung zuzuführen.

Viele dieser Bauwerke weisen eine Vielzahl “üblicher” Schadensbilder wie Durchfeuchtungen, Holzschäden, Deformationen und Rissbildungen auf. Oft deuten charakteristische Verformungen und Rissbilder auf die Gründung als eine der möglichen Schadensursachen hin. Anhand geotechnischer Untersuchungen und Nachweise ist festzustellen, inwieweit die Schadensursache der Gründung und/oder dem Baugrund zuzuordnen ist und in welchem Umfang die Standsicherheit des Bauwerks gefährdet bzw. die Funktionsfähigkeit in unzulässiger oder nicht mehr zu tolerierender Art und Weise beeinträchtigt wird.

Der Beitrag zeigt an ausgewählten Beispielen aus der Ingenieurpraxis Vorgehensweise und konstruktive Möglichkeiten, die sowohl zur Sanierung wie auch zur Verstärkung von Gründungsbauteilen anwendbar sind.
Schraubpfähle: Herstellung, Tragfähigkeit und numerische Modellierung
Authors: Vermeer Pieter , Bernecker Oliver , Weirich Tim
Published: February 2008

Schraubpfähle stellen als Verdrängungspfähle eine interessante Alternative zu den herkömmlichen gebohrten Pfahlsystemen (z. B. Bohrpfähle, Schneckenbohrpfähle) dar, deren Herstellprozess immer mit einer Störung des anstehenden Bodens verbunden ist, was zu einem negativen Einfluss auf die Pfahltragfähigkeit führt. Die Tragfähigkeiten der mehr oder weniger als vollverdrängend einzustufenden Schraubpfähle sind vergleichbar mit denen von Rammpfählen. Eine vibrationsfreie und geräuscharme Herstellung lassen einen Einsatz des Systems auch dort zu, wo gerammte Pfähle nicht geeignet sind. Die als vollverdrängende Systeme hergestellten Schraubpfähle bieten auch aus umwelttechnischen Gesichtspunkten interessante Vorteile.

Diese relativ neue Pfahlherstelltechnik wird bereits erfolgreich als effizientes Gründungssystem eingesetzt, das den Anforderungen an eine sichere und herstellfreundliche Gründung gerecht wird. Der Einsatz von üblichen, kompakten Maschinen mit hoher Produktivität fördert eine wirtschaftlich effiziente Ausführung.

Dieser Beitrag stellt das System Schraubpfähle vor und beschreibt die Herstellung und deren Einfluss auf die Tragfähigkeit. Es wird die zu erwartende Tragfähigkeit anhand von Widerstand‐Setzungs‐Linien diskutiert. Ein erster Ansatz zur numerischen Modellierung von Schraubpfählen wird anhand von Vergleichsberechnungen vorgestellt.
Antibacterial hydrogels of amino acid‐based cationic amphiphiles
Authors: Roy Sangita , Das Prasanta Kumar
Published: February 2008

Development of biomaterials, which are inherently antibacterial having broad‐spectrum activity against both Gram‐positive and Gram‐negative bacteria with considerable biocompatibility, is of tremendous importance in biomedicinal chemistry. Microbial infections are still of great concern, often originated from indwelling medical devices typically in hospitalized patients. To this end, hydrogelating soft materials particularly from low‐molecular‐weight (LMW) gelators have generated significant interest in preparing and modifying biomedicinal implants. Herein, we have developed L‐tryptophan based cationic amphiphilic hydrogelators with varying degree of hydrophobicity that exhibited remarkable bactericidal activity against wide range of Gram‐positive (MIC = 0.1–75 µg/mL) and Gram‐negative bacteria (MIC = 0.5–5 µg/mL). Antimicrobial efficacy of the amphiphiles was greatly influenced by their alkyl chain length. This bactericidal effect of cationic hydrogelators is quite comparable or in some cases markedly better than that of clinically available antibiotics. Most excitingly, they selectively attack the bacterial pathogens while remain biocompatible to the mammalian cells. Thus, we have developed LMW biocompatible, inherently antibacterial hydrogels having potential applications in biomedicines. Biotechnol. Bioeng. 2008;100: 756–764. © 2008 Wiley Periodicals, Inc.
A hybrid‐Trefftz finite element model for Helmholtz problem
Authors: Sze K. Y. , Cheung Y. K.
Published: February 2008

In this paper, a hybrid‐Trefftz four‐node quadrilateral element model is formulated for Helmholtz problem. In this model, two Helmholtz approximations are defined. The first approximation is obtained by nodal interpolation, and the second approximation is truncated from a Trefftz solution set. A hybrid variational functional is employed to enforce the equality of and other necessary conditions on the two approximations. From the numerical tests, it can be seen that the hybrid model is markedly more accurate than the conventional finite element model. Copyright © 2008 John Wiley & Sons, Ltd.
Design of current‐mode MOSFET‐C filters using OTRAs
Authors: Hwang Yuh‐Shyan , Wu Dong‐Shiuh , Chen Jiann‐Jong , Shih Chun‐Chi , Chou Wen‐Shou
Published: February 2008

In this paper, third‐order current‐mode MOSFET‐C filters that use operational transresistance amplifiers (OTRAs) with little parasitic capacitance effects are presented. On the basis of the proposed systematic method and design procedure, we can efficiently synthesize third‐order active filters with OTRAs along with simplified MOSFET resistor circuits, and all virtually grounded capacitors. Third‐order current‐mode Chebychev low‐pass and high‐pass filters are realized to verify the validity of the theoretical analysis. Experimental results employing commercially available current feedback amplifiers are also given. Copyright © 2008 John Wiley & Sons, Ltd.
Increasing the throughput of HomePNA
Authors: Amodei Aurelio , Costa Luís Henrique M. K. , Duarte Otto Carlos M. B.
Published: February 2008

In this paper we propose a new medium access mechanism for HomePNAv2 and HomePNAv3 standards. This mechanism uses a priority aggregation mechanism to avoid collisions, increasing these protocols throughput. Furthermore, this mechanism does not require modifying standards, since it can be implemented over their actual MAC sublayers. Simulation results show that the proposed mechanism is able to increase the throughput up to 44% for HomePNAv2 and 36% for HomePNAv3. Moreover, we also show how this mechanism affects network delay, analyzing average delay and jitter for all protocols presented. Copyright © 2008 John Wiley & Sons, Ltd.
Probabilistic evaluation of seismic performance of 3‐story 3D one‐ and two‐way steel moment‐frame structures
Authors: Tagawa Hiroyuki , MacRae Gregory , Lowes Laura
Published: February 2008

This paper presents the results of a probabilistic evaluation of the seismic performance of 3D steel moment‐frame structures. Two types of framing system are considered: one‐way frames typical of construction in the United States and two‐way frames typical of construction in Japan. For each framing system, four types of beam–column connections are considered: pre‐Northridge welded‐flange bolted‐web, post‐Northridge welded‐flange welded‐web, reduced‐beam‐section, and bolted‐flange‐plate connections. A suite of earthquake ground motions is used to compute the annual probability of exceedence (APE) for a series of drift demand levels and for member plastic‐rotation capacity. Results are compared for the different framing systems and connection details. It is found that the two‐way frames, which have a larger initial stiffness and strength than the one‐way frames for the same beam and column volumes, have a smaller APE for small drift demands for which members exhibit no or minimal yielding, but have a larger APE for large drift demands for which members exhibit large plastic rotations. However, the one‐way frames, which typically comprise a few seismic frames with large‐sized members that have relatively small rotation capacities, may have a larger APE for member failure. The probabilistic approach presented in this study may be used to determine the most appropriate frame configuration to meet an owner's performance objectives. Copyright © 2008 John Wiley & Sons, Ltd.
The effects of cigarette costs on BMI and obesity
Authors: Baum Charles L.
Published: February 2008

About 30% of Americans are currently obese, which is roughly a 100% increase from 25 years ago. Public health officials have consequently become alarmed because recent research indicates that societal costs of obesity now exceed those of cigarette smoking and alcoholism. Cigarette taxes may have exacerbated the prevalence of obesity. In 1964, the US Surgeon General issued its first report relating smoking and health, and since that time, federal and state governments have increased cigarette taxes in a successful effort to reduce cigarette smoking. However, because cigarette smoking and obesity seem inversely related, cigarette taxes may have simultaneously increased obesity. This paper examines the effects of cigarette costs on BMI and obesity and finds that they have significant positive effects. This paper attempts to reconcile conflicting evidence in the literature by controlling more carefully for correlation with state‐specific time trends using panel data. Results indicate that the net benefit to society of increasing cigarette taxes may not be as large as previously thought, though this research in no way concludes that they should be decreased to prompt weight loss. Copyright © 2008 John Wiley & Sons, Ltd.
A randomized, prospective trial of ribavirin 400 mg/day versus 800 mg/day in combination with peginterferon alfa-2a in hepatitis C virus genotypes 2 and 3
Authors: Ferenci Peter , Brunner Harald , Laferl Hermann , Scherzer Thomas-Matthias , Maieron Andreas , Strasser Michael , Fischer Gabriele , Hofer Harald , Bischof Martin , Stauber Rudolf , Gschwantler Michael , Steindl-Munda Petra , Staufer Katharina , Löschenberger Karin
Published: February 2008

We compared the efficacy and tolerability of 24 weeks of treatment with ribavirin 800 mg/day (group A) or 400 mg/day (group B) plus peginterferon alfa-2a 180 μg/week in treatment-naive patients infected with hepatitis C virus (HCV) genotype 2 or 3. A total of 97 of 141 patients randomized to group A (68.8%, 95% confidence interval [CI] 60.5%-76.3%) and 90 of 141 patients randomized to group B (63.8; 95% CI 55.3%-71.7%) achieved a sustained virological response, defined as undetectable serum HCV RNA at the end of untreated follow-up (week 48). Among patients infected with genotype 3, the rate of sustained virological response was 67.5% (95% CI 58.4%-75.6%) in group A and 63.9% (95% CI 54.7%-72.4%) in group B, and among patients infected with genotype 2, the rate of sustained virological response was 77.8% (95% CI 54.2%-93.6%) in group A and 55.6% (95% CI 38.4%-83.7%) in group B. Relapse rates in the 2 treatment groups were similar (17% in group A and 20% in group B). The incidence of adverse events, laboratory abnormalities, and dose reductions was similar in the 2 treatment groups.

Conclusion:

The results suggest that when administered for 24 weeks with peginterferon alfa-2a, ribavirin doses of 400 and 800 mg/day produce equivalent outcomes in patients infected with HCV genotype 3.
The development of attention and response inhibition in early childhood
Authors: Bartgis Jami , Thomas David G. , Lefler Elizabeth K. , Hartung Cynthia M.
Published: February 2008

The goal of this study was to examine the development of attention and response inhibition from ages 5 to 7. Forty children (20 5‐year‐olds and 20 7‐year‐olds) completed four counterbalanced phases of a continuous performance task. Phase 1 was designed to measure attention without distraction, Phase 2 was designed to measure attention with distraction, Phase 3 was designed to measure attention and response inhibition without distraction, and Phase 4 was designed to measure attention and response inhibition with distraction. With regard to attention, 7‐year‐olds performed significantly better than 5‐year‐olds. This age difference was more pronounced when distraction was present. With regard to response inhibition, there were no significant age differences. These results appear to suggest that attention improves between ages 5 and 7 but response inhibition does not. However, conclusions regarding response inhibition were limited because the distraction appeared to have had too powerful an effect on the 5‐year‐olds. Implications and future directions are discussed. Copyright © 2008 John Wiley & Sons, Ltd.
Never look a gift horse in the mouth or should you? Upgrading the Hare Irrigation System in Southern Ethiopia
Authors: Wegerich Kai , Dubale Tesfaye , Bruins Bert
Published: February 2008

The upgrading of the Hare Irrigation System was a joint undertaking of the governments of Ethiopia and the People's Republic of China. After completion of the primary and the secondary canals, farmers refused to take over responsibility of the system. Existing literature on the Hare Irrigation System does not differentiate between various farmer groups and their interests. This study highlights the differences in perception of head‐end, middle and tail‐end farmers. The main group that is not satisfied with the system are the head‐enders, because they are partly excluded from using it. While the middle and tail‐end farmers are satisfied with the new irrigation system, they are unhappy because they have not received the “promised” compensation. Overall, the paper highlights the lack of transparency and communication between the local community, the government and the Chinese design and construction agency, which appears to be the main reason for the dissatisfaction of parts of the local community. Copyright © 2008 John Wiley & Sons, Ltd.
PSM/SH2B1 splice variants: Critical role in src catalytic activation and the resulting STAT3s‐mediated mitogenic response
Authors: Zhang Manchao , Deng Youping , Riedel Heimo
Published: February 2008

A role of PSM/SH2B1 had been shown in mitogenesis and extending to phenotypic cell transformation, however, the underlying molecular mechanism remained to be established. Here, four alternative PSM splice variants and individual functional protein domains were compared for their role in the regulation of Src activity. We found that elevated cellular levels of PSM variants resulted in phenotypic cell transformation and potentiated cell proliferation and survival in response to serum withdrawal. PSM variant activity presented a consistent signature pattern for any tested response of highest activity observed for gamma, followed by delta, alpha, and beta with decreasing activity. PSM‐potentiated cell proliferation was sensitive to Src inhibitor herbimycin and PSM and Src were found in the same immune complex. PSM variants were substrates of the Src Tyr kinase and potentiated Src catalytic activity by increasing the Vmax and decreasing the Km for ATP with the signature pattern of variant activity. Dominant‐negative PSM peptide mimetics including the SH2 or PH domains inhibited Src catalytic activity as well as Src‐mediated phenotypic cell transformation. Activation of major Src substrate STAT3 was similarly potentiated by the PSM variants in a Src‐dependent fashion or inhibited by PSM domain‐specific peptide mimetics. Expression of a dominant‐negative STAT3 mutant blocked PSM variant‐mediated phenotypic cell transformation. Our results implicate an essential role of the PSM variants in the activation of the Src kinase and the resulting mitogenic response—extending to phenotypic cell transformation and involving the established Src substrate STAT3. J. Cell. Biochem. J. Cell. Biochem. 104: 105–118, 2008. © 2008 Wiley‐Liss, Inc.
Src‐Tyrosine kinases are major agents in mitochondrial tyrosine phosphorylation
Authors: Tibaldi Elena , Brunati Anna Maria , Massimino Maria Lina , Stringaro Annarita , Colone Marisa , Agostinelli Enzo , Arancia Giuseppe , Toninello Antonio
Published: February 2008

Mitochondrial tyrosine phosphorylation is emerging as an important mechanism in regulating mitochondrial function. This article, aimed at identifying which kinases are the major agents in mitochondrial tyrosine phosphorylation, shows that this role should be attributed to Src family members. Indeed, various members of this family, for example, Fgr, Fyn, Lyn, c‐Src, are constitutively present in the internal structure of mitochondria as well as Csk, a key enzyme in the regulation of the activity of this family. By means of different approaches, biochemical fractioning, Western blotting and immunogold analysis “in situ” of phosphotyrosine signaling, evidence is reported on the existence of a signal transduction pathway from plasma membrane to mitochondria, resulting in increasing Src‐dependent mitochondrial tyrosine phosphorylation. The activation of Src kinases at mitochondrial level is associated with the proliferative status where several mitochondrial proteins are specifically tyrosine‐phosphorylated. J. Cell. Biochem. 104: 840–849, 2008. © 2008 Wiley‐Liss, Inc.
Effect of UV irradiation on colorectal cancer cells with acquired TRAIL resistance
Authors: Kim Seong C. , Park Sung‐Soo , Lee Yong J.
Published: February 2008

Tumor necrosis factor‐related apoptosis‐inducing ligand (TRAIL) is a member of the TNF superfamily. TRAIL shows strong cytotoxicity to many cancer cells but minimal cytotoxicity to most normal cells. Interestingly, our recent studies have demonstrated that pretreatment with TRAIL induces acquired resistance to TRAIL (Song et al. 2007 J Biol Chem 282: 319). Acquired TRAIL resistance develops within 1 day and gradually decays within 5 days after TRAIL treatment. In our current study, we examined whether human colorectal carcinoma CX‐1 cells with acquired TRAIL resistance are resistant to UV irradiation as well. CX‐1 cells were treated with 200 ng/ml TRAIL for 6 h and incubated various times (0.25–5 days) and then challenged to UV irradiation. Unexpectedly, we observed an increase in apoptosis in acquired TRAIL resistant cells after UVC as well as UVB exposure. This was due to an increase in caspase activation which was mediated through cytochrome c release. These results suggest that cells with acquired TRAIL resistance are sensitive to UV irradiation. J. Cell. Biochem. 104: 1172–1180, 2008. © 2008 Wiley‐Liss, Inc.
Intracellular GSH level is a factor in As4.1 juxtaglomerular cell death by arsenic trioxide
Authors: Han Yong Hwan , Kim Sung Zoo , Kim Suhn Hee , Park Woo Hyun
Published: February 2008

Arsenic trioxide has been known to regulate many biological functions such as cell proliferation, apoptosis, differentiation, and angiogenesis in various cell lines. We investigated the involvement of GSH and ROS such as H2O2 and O in the death of As4.1 cells by arsenic trioxide. The intracellular ROS levels were changed depending on the concentration and length of incubation with arsenic trioxide. The intracellular O level was significantly increased at all the concentrations tested. Arsenic trioxide reduced the intracellular GSH content. Treatment of Tiron, ROS scavenger decreased the levels of ROS in 10 µM arsenic trioxide‐treated cells. Another ROS scavenger, Tempol did not decrease ROS levels in arsenic trioxide‐treated cells, but slightly recovered the depleted GSH content and reduced the level of apoptosis in these cells. Exogenous SOD and catalase did not reduce the level of ROS, but did decrease the level of O. Both of them inhibited GSH depletion and apoptosis in arsenic trioxide‐treated cells. In addition, ROS scavengers, SOD and catalase did not alter the accumulation of cells in the S phase induced by arsenic trioxide. Furthermore, JNK inhibitor rescued some cells from arsenic trioxide‐induced apoptosis, and this inhibitor decreased the levels of O and reduced the GSH depletion in these cells. In summary, we have demonstrated that arsenic trioxide potently generates ROS, especially O, in As4.1 juxtaglomerular cells, and Tempol, SOD, catalase, and JNK inhibitor partially rescued cells from arsenic trioxide‐induced apoptosis through the up‐regulation of intracellular GSH levels. J. Cell. Biochem. 104: 995–1009, 2008. © 2008 Wiley‐Liss, Inc.
Merging molecular imaging and RNA interference: Early experience in live animals
Authors: Bogdanov Alexei A.
Published: February 2008

The rapid development of non‐invasive imaging techniques and imaging reporters coincided with the enthusiastic response that the introduction of RNA interference (RNAi) techniques created in the research community. Imaging in experimental animals provides quantitative or semi‐quantitative information regarding the biodistribution of small interfering RNAs and the levels of gene interference (i.e., knockdown of the target mRNA) in living animals. In this review we give a brief summary of the first imaging findings that have potential for accelerating the development and testing of new approaches that explore RNAi as a method for achieving loss‐of‐function effects in vivo and as a promising therapeutic tool. J. Cell. Biochem. 104: 1113–1123, 2008. © 2008 Wiley‐Liss, Inc.
Lack of insulin impairs Mg2+ homeostasis and transport in cardiac cells of streptozotocin‐injected diabetic rats
Authors: Reed Grant , Cefaratti Christie , Berti‐Mattera Liliana N. , Romani Andrea
Published: February 2008

Serum and tissue Mg2+ content are markedly decreased in diabetic patients and animals. At the tissue level, Mg2+ loss progresses over time and affects predominantly heart, liver and skeletal muscles. In the present study, alterations in Mg2+ homeostasis and transport in diabetic cardiac ventricular myocytes were evaluated. Cardiac tissue and isolated cardiac ventricular myocytes from diabetic animals displayed a decrease in total Mg2+ content that affected all cellular compartments. This decrease was associated with a marked reduction in cellular protein and ATP content. Diabetic ventricular myocytes were unable to mobilize Mg2+ following β‐adrenergic receptor stimulation or addition of cell permeant cyclic‐AMP. Sarcolemma vesicles purified from diabetic animals, however, transported Mg2+ normally as compared to vesicles from non‐diabetic animals. Treatment of diabetic animals with exogenous insulin for 2 weeks restored ATP and protein levels as well as Mg2+ homeostasis and transport to levels comparable to those observed in non‐diabetic animals. These results suggest that in diabetic cardiac cells Mg2+ homeostasis and extrusion via β‐adrenergic/cAMP signaling are markedly affected by the concomitant decrease in protein and ATP content. As Mg2+ regulates numerous cellular enzymes and functions, including protein synthesis, these results provide a new rationale to interpret some aspects of the cardiac dysfunctions observed under diabetic conditions. J. Cell. Biochem. 104: 1034–1053, 2008. © 2008 Wiley‐Liss, Inc.
Proteomics investigation of protein expression changes in ouabain induced apoptosis in human umbilical vein endothelial cells
Authors: Qiu Jie , Gao Hai‐Qing , Li Bao‐Ying , Shen Lin
Published: February 2008

Ouabain is Na+/K+_ATPase inhibitor and an endogenous regulator of blood pressure, it has dual effect on vascular endothelial cells(VEC) cell growth and VEC apoptosis is contributed to vascular dysfunction involved in vascular remolding. However, the precise mechanisms of apoptosis induced by ouabain remained unclear. The objective of this study was to identify the differently expressed proteins involved in VEC apoptosis induced by ouabain in order to explore cellular and subcellular mechanisms related to ouabain actions. Human umbilical vein endothelial cells (HUVEC) were exposed to increasing concentrations (0.1 nM to 10 µM) of ouabain at 12–48 h intervals. Cell viability tests revealed that high concentrations of ouabain inhibited cell growth. Flow cytometry and caspase‐3 activity analysis confirmed that apoptosis was primarily responsible for ouabain induced cell death. Two‐dimensional electrophoresis in conjunction with mass spectrometry revealed that the ouabain‐induced apoptosis was accompanied by regulated expression of programmed cell death protein 6, cytochrome C1, endothelin converting enzyme, claudin‐1, reticulon‐4, galectin‐1, ras‐related protein rab‐11B, calnexin, profilin‐1 and heat shock protein 60 (HSP60). Further study on cytochrome c and HSP60 demonstrated that levels of mitochondria and cytosol cytochrome c and HSP60 changed in response to ouabain treatment. Data showed that mitochondria proteins such as HSP60 interferes with HSP60‐Bax interactions played an important role in ouabain induced apoptosis. These data bring new sights into physiological role for ouabain in VEC apoptosis and vascular remodeling, thus provide new strategies for new anti‐cardiovascular disease drug development or the identification of biomarkers for vascular dysfunction in ouabain related hypertension. J. Cell. Biochem. 104: 1054–1064, 2008. © 2008 Wiley‐Liss, Inc.
Binding of RFX2 and NF‐Y to the testis‐specific histone H1t promoter may be required for transcriptional activation in primary spermatocytes
Authors: vanWert Jane M. , Wolfe Steven A. , Grimes Sidney R.
Published: February 2008

The testis‐specific linker histone H1t is transcribed exclusively in pachytene spermatocytes during spermatogenesis. The H1t promoter contains two imperfect inverted repeats which together comprise the X‐box motif that is known to bind the transcription factor regulatory factor X (RFX). Out of all the histone H1 family promoters this motif appears only in the H1t promoter and may contribute to H1t tissue‐specific expression. We show by Western blotting, EMSA, ChIP analysis, and real‐time RT‐PCR that the rat H1t X‐box is bound by RFX2 in vivo in spermatocytes. We demonstrate that transcription factor NF‐Y binds to the CCAAT‐box motif that is located downstream and adjacent to the X‐box and that testis NF‐Y interacts either directly or indirectly with RFX2. Furthermore, we show that both the X‐box and CCAAT‐box are required for promoter activity and that co‐expression of RFX2 greatly enhances testis histone H1t promoter activity in the GC‐1spg germinal cell line. J. Cell. Biochem. 104: 1087–1101, 2008. © 2008 Wiley‐Liss, Inc.
Lysophosphatidic acid promotes cell invasion by up‐regulating the urokinase‐type plasminogen activator receptor in human gastric cancer cells
Authors: Kim Mi Ha , Park Jung Sun , Chang Hee Jung , Baek Min Kyung , Kim Hyeong Rok , Shin Boo Ahn , Ahn Bong Whan , Jung Young Do
Published: February 2008

There is a strong correlation between the overexpression of urokinase‐type plasminogen activator receptor (uPAR) and gastric cancer invasion. This study examined the effect of phospholipid lysophosphatidic acid (LPA) on uPAR expression in human gastric cancer AGS cells and the underlying signal transduction pathways. Treating human gastric AGS cells with LPA induced the expression of uPAR mRNA and promoter activity in both a time‐ and dose‐dependent manner. Small interfering RNA targeting for LPA receptors, dominant negative Rho‐family GTPase (RhoA, Rac1, and Cdc42) and an expression vector encoding a mutated c‐jun (TAM67) partially blocked the LPA‐induced uPAR expression. Site‐directed mutagenesis and electrophoretic mobility shift studies showed that the transcription factors activation protein‐1 (AP‐1) and nuclear factor (NF)‐κB are essential for the LPA‐induced uPAR transcription. In addition, AGS cells treated with LPA showed enhanced invasion, which was partially abrogated by the uPAR‐neutralizing antibodies and inhibitors of Rho kinase, JNK, and NF‐κB. This suggests that LPA induces uPAR expression through the LPA receptors, Rho‐family GTPase, JNK, AP‐1 and NF‐κB signaling pathways, which in turn stimulates the cell invasiveness of human gastric cancer AGS cells. J. Cell. Biochem. 104: 1102–1112, 2008. © 2008 Wiley‐Liss, Inc.
Roles of Wnt signalling in bone growth, remodelling, skeletal disorders and fracture repair
Authors: Macsai Carmen E. , Foster Bruce K. , Xian Cory J.
Published: February 2008

Wnt signalling has an essential role in regulating bone formation and remodelling during embryonic development and throughout postnatal and adult life. Specifically, Wnt signalling regulates bone formation by controlling embryonic cartilage development and postnatal chondrogenesis, osteoblastogenesis, osteoclastogenesis, endochondral bone formation, and bone remodelling. Abnormalities in the function of Wnt genes give rise to or contribute to the development of several pathological bone conditions, including abnormal bone mass, osteosarcomas and bone loss in multiple myeloma. Furthermore, Wnt signalling is activated during bone fracture repair and plays a crucial role in regulating bone regeneration. J. Cell. Physiol. 215: 578–587, 2008. © 2008 Wiley‐Liss, Inc.
HIV‐1 Tat inhibits NGF‐Induced Egr‐1 transcriptional activity and consequent p35 expression in neural cells
Authors: Darbinian Nune , Darbinyan Armine , Czernik Marta , Peruzzi Francesca , Khalili Kamel , Reiss Krzysztof , Gordon Jennifer , Amini Shohreh
Published: February 2008

Infection with HIV‐1 causes degeneration of neurons leading to motor and cognitive dysfunction in AIDS patients. One of the key viral regulatory proteins, Tat, which is released by infected cells, can be taken up by various uninfected cells including neurons and by dysregulating several biological events induces cell injury and death. In earlier studies, we demonstrated that treatment of neuronal cells with Tat affects the nerve growth factor (NGF) signaling pathway involving MAPK/ERK. Here we demonstrate that a decrease in the level of Egr‐1, one of the targets for MAPK, by Tat has a negative impact on the level of p35 expression in NGF‐treated neural cells. Further, we demonstrate a reduced level of Egr‐1 association with the p35 promoter sequence in NGF‐treated cells expressing Tat. As p35, by associating with Cdk5, phosphorylates several neuronal proteins including neurofilaments and plays a role in neuronal differentiation and survival, we examined kinase activity of p35 complexes obtained from cells expressing Tat. Results from H1 kinase assays showed reduced activity of the p35 complex from Tat‐expressing cells in comparison to that from control cells. Accordingly, the level of phosphorylated neurofilaments was diminished in Tat‐expressing cells. Similarly, treatment of PC12 cells with Tat protein or supernatant from HIV‐1 infected cells decreased kinase activity of p35 in these cells. These observations ascribe a role for Tat in altering p35 expression and its activity that affects phosphorylation of proteins involved in neuronal cell survival. J. Cell. Physiol. 216: 128–134, 2008. © 2008 Wiley‐Liss, Inc.
The tetraspanin CD9 modulates epidermal growth factor receptor signaling in cancer cells
Authors: Murayama Yoko , Shinomura Yasuhisa , Oritani Kenji , Miyagawa Jun‐Ichiro , Yoshida Hitoshi , Nishida Makoto , Katsube Fumie , Shiraga Masamichi , Miyazaki Tamana , Nakamoto Taisei , Tsutsui Shusaku , Tamura Shinji , Higashiyama Shigeki , Shimomura Iichirou , Hayashi Norio
Published: February 2008

CD9 is a member of the tetraspanins, and has been shown to be involved in a variety of cellular activities such as migration, proliferation, and adhesion. In addition, it has been known that CD9 can associate with other proteins. Here we demonstrated the physical and functional association of CD9 with epidermal growth factor receptor (EGFR) on MKN‐28 cells. Double‐immunofluorescent staining and immunoprecipitation demonstrated the complex formation of CD9‐EGFR and CD9‐β1integrin, and that both complexes are colocalized on the cell surface especially at the cell–cell contact site. Anti‐CD9 monoclonal antibody ALB6 induced a dotted or patch‐like aggregation pattern of both CD9‐EGFR and CD9‐β1integrin. The internalization of EGFR after EGF‐stimulation was significantly enhanced by the treatment with ALB6. CD9 can associate with EGFR in hepatocellular carcinoma cells (HepG2/CD9) and Chinese hamster ovary cancer cells (CHO‐HER/CD9), which were transfected with pTJ/human EGFR/CD9. Furthermore expression of CD9 specifically attenuated EGFR signaling in CHO‐HER/CD9 cells through the down regulation of surface expression of EGFR. These results suggest that CD9 might have an important role that attenuates EGFR signaling. Therefore, CD9 not only associates EGFR but also a new regulator, which may affect EGF‐induced signaling in cancer cells. J. Cell. Physiol. 216: 135–143, 2008. © 2008 Wiley‐Liss, Inc.
Overexpression of bax induces down‐regulation of store‐operated calcium entry in prostate cancer cells
Authors: Li Na , Zheng Lin , Lin Peihui , Danielpour David , Pan Zui , Ma Jianjie
Published: February 2008

Store‐operated Ca2+ channels control homeostasis between extracellular Ca2+ reservoir and intracellular Ca2+ storage and play important roles in apoptosis in a wide variety of cells, including prostate epithelia. Recent studies have shown that the acquired apoptosis‐resistant nature of androgen‐independent prostate cancer is associated with reduced function of store‐operated Ca2+ entry (SOCE). This study investigates the functional interaction between Bax and SOCE in the apoptosis signaling cascade in prostate cancer. Our previous findings show that NRP‐154, an androgen‐independent prostate cancer cell line, could sustain overexpression of exogenous Bax without undergoing apoptosis. Here we show that sustained overexpression of Bax in NRP‐154 cells leads to down‐regulation of SOCE and reduced Ca2+ storage inside the endoplasmic reticulum. While reduced SOCE may represent an adaptive mechanism for cell survival, increased levels of Bax in the latent state enhances the sensitivity of NRP‐154 cells to TGF‐β and thapsigargin‐induced apoptosis. This enhanced apoptosis can be reduced by 2‐aminoethoxydiphenyl borate (2‐APB), an inhibitor of SOCE, or reversed under conditions where SOCE is only partially activated. Our results demonstrate a functional interaction between Bax and SOCE in apoptosis of prostate cancer, and support the concept that improving this interaction has therapeutic implications for prostate cancer. J. Cell. Physiol. 216: 172–179, 2008. © 2008 Wiley‐Liss, Inc.
TRPC5 channels undergo changes in gating properties during the activation‐deactivation cycle
Authors: Obukhov Alexander G. , Nowycky Martha C.
Published: February 2008

TRPC5 are non‐specific cation channels activated through phospholipase C‐dependent pathways, although the precise gating mechanism is unknown. TRPC5 current–voltage relationships (I–Vs) change systematically during the activation‐deactivation cycle, shifting between outwardly rectifying and doubly rectifying shapes. Since several TRP family members exhibit voltage‐dependent properties, we investigated whether the various I–V relationships were due to changes in gating. Using patch‐clamp recordings of rat TRPC5 transfected HEK293 cells, we found that TRPC5 currents had distinct biophysical characteristics correlated with individual I–V shapes, a phenomenon we call ‘phases.’ At rest, channels were closed at most potentials, although strong depolarizations (>+80 mV) stimulated small outward currents (Phase 0). For 10–15 sec after activation, voltage steps evoked small inward and large outward currents with time‐ and voltage‐dependent kinetics (Phase 1, outwardly‐rectifying I–Vs). At maximal inward amplitude, currents were voltage‐independent at all potentials (Phase 2, doubly‐rectifying I–Vs owing to Mg2+ block). During desensitization (Phase 3), currents reverted to a Phase 1‐like voltage‐dependence. La3+ ions potentiated inward TRPC5 currents by promoting a reversible transition from Phase 3 to Phase 2. Single channel recordings revealed asymmetric conductance properties with values of ∼40 pS at negative potentials and ∼130 pS at >+60 mV. Mutation of D633, a cytoplasmic residue that mediates Mg2+ block, decreased channel activity at negative potentials during Phase 2. We conclude that TRPC5 gating properties can switch reversibly between voltage‐dependent and voltage‐independent states. The modulation of phase transitions by external agents such as La3+ and EBP50, a scaffolding protein, may constitute a novel mechanism for regulation of channel activity. J. Cell. Physiol. 216: 162–171, 2008. © 2008 Wiley‐Liss, Inc.