bluuebunny/crossref_metadata_2025 huggingface dataset:
DFT modeling of reactivity in an ionic liquid: How many ion pairs?
Authors: Bessac Fabienne , Maseras Feliu
Published: October 2007

The modeling of reactivity in an ionic liquid is examined with DFT and DFT/MM calculations on the SN2 intramolecular rearrangement of the Z‐phenylhydrazone of 3‐benzoyl‐5‐phenyl‐1,2,4‐oxadiazole into 4‐benzoylamino‐2,5‐diphenyl‐1,2,3‐triazole induced by amines. Experimental research has shown that the reaction occurs in 1‐butyl‐3‐methylimidazolium tetrafluoroborate, and in conventional organic solvents such as acetonitrile with comparable rates. The structure for the reactants, transition states and products for the rate‐determining step are optimized, and the energy barrier is computed in three different environments: gas phase, water solvent, and ionic liquid. The results are encouraging in describing the energy barrier in the ionic liquid. A simple model is formulated to explain the effect of the solvent in this particular process, and a procedure to study theoretically the reactivity in an ionic liquid is proposed. © 2007 Wiley Periodicals, Inc. J Comput Chem 2008
Revisiting the relationship between the bond length alternation and the first hyperpolarizability with range‐separated hybrid functionals
Authors: Jacquemin Denis , Perpéte Eric A. , Ciofini Ilaria , Adamo Carlo
Published: October 2007

We monitor the influence of the bond length alternation (BLA) modification on the static electronic polarizability and first hyperpolarizability of two polymethineimine oligomers. Four theoretical approaches are compared: HF, PBE0, LC‐ωPBE, and MP2. For the dodecamer, both HF and PBE0 are unable to foresee even the qualitative evolution of the first hyperpolarizability when varying the BLA. On the contrary, LC‐ωPBE provides (non)linear optics properties in agreement with MP2 results, especially for the longer chains. This confirms the interest of range‐separated hybrids for the computation of the (hyper)polarizabilities of extended π‐conjugated compounds. © 2007 Wiley Periodicals, Inc. J Comput Chem 2008
RNA conformational sampling. I. Single‐nucleotide loop closure
Authors: Mak C. H.
Published: October 2007

We consider the loop‐closure problem for nucleic acids and describe an efficient numerical algorithm for closing single‐nucleotide loops in nucleic acids. Using six new internal coordinates to represent the nucleotide conformation, which we call the R‐representation, the original closure problem with six free torsion angles in each nucleotide can be reduced to one with only four degrees of freedom. Simple numerical techniques have been used to solve the resulting loop‐closure equations, and a test of the closure algorithm on a set of RNAs consisting of more than 7000 nucleotides was able to regenerate the native torsion angles in every nucleotide in the test set without exception. We show how the conformational probability density transforms when the original torsion angle representation is mapped onto the new R‐representation. We also present statistical evidence showing that the δ and ν2 torsion angles are coupled, and how this coupling affects the conformation probability density in the R‐representation. In addition to the backbone, the same loop‐closure algorithm can also be applied to close the ribose ring. The algorithm is freely available at http://tyrosine.use.edu/closure. © 2007 Wiley Periodicals, Inc. J Comput Chem 2008
Can TD‐DFT calculations accurately describe the excited states behavior of stacked nucleobases? The cytosine dimer as a test case
Authors: Santoro Fabrizio , Barone Vincenzo , Improta Roberto
Published: October 2007

By using calculations rooted in the time dependent density functional theory (TD‐DFT) we have investigated how the lowest energy excited states of a face‐to‐face π‐stacked cytosine dimer vary with the intermonomer distance (R). The perfomances of different density functionals have been compared, focussing mainly on the lowest energy single excited state of the dimer (S1)2. TD‐PBE0, TD‐LC‐ωPBE, and TD‐M05‐2X provide a picture very similar to that obtained at the CASPT2 level by Merchan et al. (J Chem Phys 2006, 125, 231102), predicting that (S1)2 has a minimum for R ∼ 3 Å, with a binding energy of ∼0.5 eV, whereas TD‐B3LYP, TD‐CAM‐B3LYP, and TD‐PBE understimate the binding energy. However, independently of the functional employed, no low‐energy spurious charge transfer transitions are predicted by TD‐DFT calculations, also when a nonsymmetric dimer is investigated, providing encouraging indications for the use of TD‐DFT for studying the excited state of π‐stacked nucleobases. © 2007 Wiley Periodicals, Inc. J Comput Chem 2008
Application of response surface methodology to optimize the operation process for regeneration of acid and base using bipolar membrane electrodialysis
Authors: Zhang Xiaoyan , Lu Wenhua , Yang Pengbo , Cong Wei
Published: October 2007

BACKGROUND: Bipolar membrane electrodialysis (BMED) has been widely used for desalination, concentration, separation, and purification in many fields. The purpose of this study is to optimize the operation conditions using response surface methodology (RSM) for the regeneration of sulfuric acid and ammonia from ammonium sulfate solution by BMED coupled with ammonia in situ stripping.

RESULTS: A three‐factor central composite design of RSM was used to analyze the effect of operation conditions (current density, flow rate, initial acid concentration) on average current efficiency (ACE) and establish the optimal operation conditions. The ACE was 76.7 ± 2.2% under optimal operation conditions (current density 23.8 mA cm−2, flow rate 27.3 L h−1, initial acid concentration 0.09 mol L−1).

CONCLUSION: A suitable regression model for predicting ACE within the ranges of variables used was developed based on experimental results. The operation conditions were optimized by RSM and the ACE obtained under the optimal operation conditions was in good agreement with the value predicted by the regression model (78%), which proved the validity of the model. Copyright © 2007 Society of Chemical Industry
Effects of tumor necrosis factor‐α on cell proliferation, prostaglandins and matrix‐metalloproteinases production in rat endometrial stromal cells cultured in vitro
Authors: Gamo Toru , Yamauchi Nobuhiko , Nishimura Kyohei , Watanabe Ryo , Matsumoto Kenji , Oozono Shinji , Kubota Kaiyu , He Pei‐Jian , Soh Tomoki , Hattori Masa‐aki
Published: October 2007

Tumor necrosis factor‐α (TNF‐α) is known as a pluripotent cell mediator, and it is implicated in the control of uterine cell growth, differentiation and function during estrous cycle and pregnancy. In this study, we investigated the effect of TNF‐α on endometrial stromal cells derived from rat uterus (rat endometrial stromal cells, RES). RES were isolated from rat endometrium at day 5 of pregnancy. Proliferation activities of RES were measured by using bromodeoxyuridine (BrdU) labeling kit, the productions of prostaglandin E2 (PGE2) and prostaglandin F2α (PGF2α) were measured by enzyme immunoassay kits and the production of matrix metalloproteinases (MMPs) was analyzed by gelatin‐zymography. TNF‐α, as well as epidermal growth factor and fibroblast growth factor‐2, significantly increased the proliferation activity of RES (P<0.05). TNF‐α selectively stimulated the production of PGE2 in RES (P<0.05), but not the production of PGF2α. Additionally, TNF‐α did not stimulate the production of MMPs in RES at the concentration of 5 ng/mL, compared with the control groups (P>0.05). In conclusion, this study demonstrates several regulational functions of TNF‐α on RES using in vitro culture system. The effects of TNF‐α on proliferation and MMP production of RES have been shown for the first time. We believe that these results demonstrate part of the functions of TNF‐α in endometrium and contribute to the better understanding of endometrial functions. J. Exp. Zool. 307A:699–707, 2007. © 2007 Wiley‐Liss, Inc.
An efficient RNA‐cleaving DNA enzyme can specifically target the 5′‐untranslated region of severe acute respiratory syndrome associated coronavirus (SARS‐CoV)
Authors: Wu Shuwen , Xu Junqiang , Liu Jiangxia , Yan Xuan , Zhu Xiaodong , Xiao Gengfu , Sun Lunquan , Tien Po
Published: October 2007

Background

The worldwide epidemic of severe acute respiratory syndrome (SARS) in 2003 was caused by a novel coronavirus called SARS‐CoV. We report the use of DNAzyme (catalytic DNA) to target the 5′‐untranslated region (5′UTR) of a highly conserved fragment in the SARS genome as an approach to suppression of SARS‐CoV replication. A mono‐DNA enzyme (Dz‐104) possessing the 10–23 catalytic motif was synthesized and tested both in vitro and in cell culture.

Materials and methods

SARS‐CoV total RNA was isolated, extracted from the SARS‐CoV‐WHU strain and converted into cDNA. We designed a RNA‐cleaving 10–23 DNAzyme targeting at the loop region of the 5′UTR of SARS‐CoV. The designed DNAzyme, Dz‐104, and its mutant version, Dz‐104 (mut), as a control consist of 9 + 9 arm sequences with a 10–23 catalytic core. In vitro cleavage was performed using an in vitro transcribed 5′UTR RNA substrate. A vector containing a fused 5′UTR and enhanced green fluorescent protein (eGFP) was co‐transfected with the DNAzyme into E6 cells and the cells expressing eGFP were visualized with fluorescence microscopy and analyzed by fluorescence‐activated cell sorting (FACS).

Results and conclusions

Our results demonstrated that this DNAzyme could efficiently cleave the SARS‐CoV RNA substrate in vitro and inhibit the expression of the SARS‐CoV 5′UTR‐eGFP fusion RNA in mammalian cells. This work presents a model system to rapidly screen effective DNAzymes targeting SARS and provides a basis for potential therapeutic use of DNA enzymes to combat the SARS infection. Copyright © 2007 John Wiley & Sons, Ltd.
AdΔ24 and the p53‐expressing variant AdΔ24‐p53 achieve potent anti‐tumor activity in glioma when combined with radiotherapy
Authors: Idema Sander , Lamfers Martine L.M. , van Beusechem Victor W. , Noske David P. , Heukelom Stan , Moeniralm Sharif , Gerritsen Winald R. , Vandertop W. Peter , Dirven Clemens M.F.
Published: October 2007

Background

The conditionally replicating adenovirus (CRAd) AdΔ24‐p53 replicates selectively in Rb mutant cells, and encodes the p53 suppressor protein. It has shown improved oncolytic potency compared to the parental control AdΔ24. As exogenous p53 has been shown to enhance radiosensitivity, the combination of AdΔ24‐p53 and AdΔ24 with radiotherapy was assessed in vitro and in vivo against the therapy resistant gliomas.

Methods

In glioma cells, multicellular spheroids and animal xenografts the efficacy of combination therapy was assessed. P53 phosphorylation, induction of apoptosis and viral replication were determined following single or combination therapies.

Results

In vitro, AdΔ24‐p53 was more effective against glioma cells than the control AdΔ24. Addition of irradiation equally increased the efficacy of both AdΔ24‐p53 and AdΔ24 resulting in improved oncolysis compared to single agent treatment. Radiotherapy did not significantly change the replication kinetics of AdΔ24‐p53 or AdΔ24. No detectable increase in p53 phosphorylation was observed but combination of radiotherapy and AdΔ24‐p53 caused an increase in the percentage of apoptotic cells. In vivo, combination therapy with either AdΔ24 or AdΔ24‐p53 significantly increased the number of mice demonstrating tumor regression (100%) as well as long‐term survival (50%). No differences between viruses were noted.

Conclusions

Exogenous p53 expression does not appear to increase the synergistic interaction of CRAds combined with radiotherapy. These results however do indicate that radiotherapy provides the time frame in which AdΔ24 and AdΔ24‐p53 can eradicate established tumors that would otherwise escape treatment, and establishes the need to combine these modalities to form an effective anti‐cancer treatment. Copyright © 2007 John Wiley & Sons, Ltd.
The impact of vertical resolution on regional model simulation of the west African summer monsoon
Authors: Druyan Leonard M. , Fulakeza Matthew , Lonergan Patrick
Published: October 2007

The RM3 regional climate model is used to simulate the west African summer monsoon for six June–September seasons using NCEP reanalysis data for lateral boundary forcing. The study compares the performance of the previously published 16‐level version with a newly tested 28‐level version, both running on a horizontal grid with 0.5° spacing, in order to determine what improvements in simulations are achieved by increased vertical resolution. Comparisons between the performances include diagnostics of seasonal mean precipitation rates and circulation, vertical profiles of cumulus heating rates, frequencies of shallow and deep convection and diagnostics related to transient African easterly waves (AEWs). The characteristics of a composite AEW simulated at both vertical resolutions are presented. Results show that the most significant impact of increasing the vertical resolution is stronger circulation, stronger vertical wind shear and higher amplitude AEWs. The simulations with higher vertical resolution also achieve higher peaks of cumulus latent heating rates. Spatial–temporal correlations between simulated daily 700 mb meridional winds versus corresponding NCEP reanalysis data and simulated daily precipitation versus estimates from the Tropical Rainfall Measurement Mission (TRMM) archive were equally high at both vertical resolutions. Copyright © 2007 Royal Meteorological Society
Programmable cells of monocytic origin (PCMO): A source of peripheral blood stem cells that generate collagen type II‐producing chondrocytes
Authors: Pufe Thomas , Petersen Wolf , Fändrich Fred , Varoga Deike , Wruck Christoph J. , Mentlein Rolf , Helfenstein Andreas , Hoseas Daniela , Dressel Stefanie , Tillmann Bernhard , Ruhnke Maren
Published: October 2007

The focus of this study was a new adult pluripotent cell derived from human peripheral blood monocytes identified as a “programmable cell of monocytic origin” (PCMO). In contrast to bone marrow‐derived stem cells, these cells can be harvested from peripheral venous blood without aspiration of the bone marrow and have multilineage potential comparable to that of mesenchymal stem cells (MSC). The aim of this study was to evaluate the potential of PCMOs to differentiate into collagen type II‐producing chondrocytes using various extrinsic cues (TGFβ‐1, IGF‐1, BMP‐2, and BMP‐7). Collagen type I and II proteins were localized using immunohistochemistry and quantified by enzyme‐linked immunosorbent assays (ELISA). The shape of the differentiating PCMOs was monitored with electron microscopy. Collagen type I and II messenger RNA expression was analyzed using real‐time reverse transcriptase‐polymerase chain reaction (RT PCR) and regular RT PCR. Immunohistochemistry revealed a strong accumulation of collagen type II after a 6‐week incubation period with BMP‐2, BMP‐7, TGF‐β, IGF‐I, and TGF‐β, and IGF‐1. Collagen type I was only mildly induced by the applied stimulants. Electron microscopy findings showed a shift from a monocyte‐like structure to a chondrocyte‐like structure after 2 weeks of stimulation. Stimulation of PCMOs with BMP‐2, BMP‐7, TGF‐β, IGF‐I, and TGF‐β, and IGF‐1 induced a chondrogenic differentiation with continuous expression of collagen type II mRNA and protein over several weeks time. Collagen type I and II expression in undifferentiated PCMOs or in control cells incubated without any stimulant was not detected. PCMOs have the potential to differentiate into collagen type II synthesizing chondrocytes. The ability to reprogram and differentiate PCMOs from peripheral blood into sizable quantities might enable their clinical application in cartilage repair after mechanical injury or in cases of osteoarthritis. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:304–313, 2008
Development and validation of an HPLC method for the determination of penicillin antibiotics residues in bovine muscle according to the European Union Decision 2002/657/EC
Authors: Samanidou Victoria F. , Nisyriou Styliani A. , Papadoyannis Ioannis N.
Published: October 2007

A high‐performance liquid chromatographic method was developed for the determination of five penicillins: penicillin G (PENG), penicillin V (PENV), oxacillin (OX), cloxacillin (CLO), and dicloxacillin (DICLO), in bovine muscle. Samples were macerated with a mixture of H2O/CH3CN (1:1) and purified using RP‐8 Adsorbex SPE cartridges after centrifugation, with mean recovery from spiked samples higher than 89%. The separation of the examined penicillins was achieved on an analytical column, an Inertsil C8 5 μm, 250×4 mm2, at ambient temperature. The mobile phase consisted of 0.1% TFA/ACN 50:50 v/v delivered isocratically at a flow rate of 1.1 mL/min. Analytes were monitored at 240 nm. The procedure was validated according to the European Union Decision 2002/657/EC by means of selectivity, stability, decision limit, detection capability, accuracy, and precision. Method's LOQ values achieved were 54 μg/kg for PENG and DICLO, 46 μg/kg for PENV, 16 μg/kg for OX, and 43 μg/kg for DICLO. The detection capabilities (CCβ) were 73.6 μg/kg for PENG, 29.1 μg/kg for PENV, 350.6 μg/kg for OX, 379.9 μg/kg for CLO, and 355.8 μg/kg for DICLO. The method was applied to various samples from the local market. Two penicillins were identified by photodiode array (PDA) detection and quantified.
Analysis of phenolic acids in fruits by HPLC with monolithic columns
Authors: Biesaga Magdalena , Ochnik Urszula , Pyrzynska Krystyna
Published: October 2007

Reversed‐phase HPLC was optimised for simultaneous determination of several derivatives of benzoic and hydroxycinnamic acids (so‐called phenolic acids) in plums using a commercially available monolithic column. Mobile phase pH and concentration of organic modifier (methanol and acetonitrile) were tested in order to obtain the best resolution. Satisfactory separation was achieved in gradient mode with a mobile phase consisting of 50 mM phosphate buffer at pH 2.2 (solvent A) and acetonitrile (solvent B). The limits of detection for a UV detector ranged between 0.098 and 2.04 μg/mL for vanillic acid and p‐hydroxyphenylacetic acid, respectively. The developed method was used for monitoring the content of polyphenolic acids in plums during their ripening process. The presence of these constituents was confirmed by checking their MS spectra.
Preparation of methacrylate monoliths
Authors: Vlakh Evgenia G. , Tennikova Tatiana B.
Published: October 2007

Rigid macroporous polymers developed in the early 1990s are widely used as efficient stationary phases for all types of chromatographic separations. The main advantages of so‐called monolithic supports are their high hydraulic permeability and the dominance of the convection over the diffusion mechanism of mass‐exchange under dynamic conditions that allow the separation to be carried out at extremely high flow rates and, consequently, during very short operation times. Among other types of macroporous polymers, the methacrylate‐based monolithic materials represent the most popular and successfully explored class of sorbents. This review is an attempt to collect together the contributions of different groups working in the area of monolith preparation. Examples of different methcrylate monomers and crosslinkers, as well as porogenic solvents, including polymer ones, used in monolith preparation are discussed.
Separation and determination of five major opium alkaloids with mixed mode of hydrophilic/cation‐exchange monolith by pressurized capillary electrochromatography
Authors: Lin Xucong , Wang Jiabin , Li Liyu , Wang Xiaochun , Lü Haixia , Xie Zenghong
Published: October 2007

A method for the separation and determination of five major opium alkaloids (narcotine, papaverine, thebaine, codeine, and morphine) in pericarpium papaveris by pressurized CEC (pCEC) with monolithic column has been developed. Under the optimum condition, linear calibration ranges of narcotine, papaverine, thebaine, codeine, and morphine were obtained as 2–85, 2–85, 5–75, 10–65, and 10–65 μg/mL, respectively. LODs of these analytes were 1.5–6.0 μg/mL. The RSD (n = 7) of the migration time and peak area were 1.94–5.24 and 4.05–8.21%, respectively. The proposed method was successfully applied to the analysis of pericarpium papaveris samples. Average recoveries of 79.0–95.9% at different fortified levels of alkaloids were achieved with RSD less than 4.6%. Meanwhile, the mechanism of the separation of the alkaloids on the monolithic column was also discussed. The result showed that the separation of alkaloids was mainly based on the mixed mode of hydrophilic interaction (HI) and cation exchange.
Real space observation of silica monoliths in the formation process
Authors: Saito Haruko , Kanamori Kazuyoshi , Nakanishi Kazuki , Hirao Kazuyuki
Published: October 2007

The macropore structure evolution of a silica monolith during the formation process was observed by laser scanning confocal microscopy (LSCM) for two kinds of systems. The obtained LSCM images were further subjected to image analysis, and the geometrical parameters were calculated. On the basis of the parameters obtained, improved compositions for high efficiency preparation of macroporous monoliths are discussed.
CEC separation of aromatic compounds and proteins on hexylamine‐functionalized N‐acryloxysuccinimide monoliths
Authors: Carbonnier Benjamin , Guerrouache Mohamed , Denoyel Renaud , Millot Marie‐Claude
Published: October 2007

Reactive organic polymer monoliths were prepared in fused‐silica capillaries by UV‐initiated free radical polymerization of N‐acryloxysuccinimide (NAS) as reactive monomer, ethylene dimethacrylate as crosslinker, azobisisobutyronitrile as initiator, and toluene as porogen. In a second synthetic step, chemical derivatization of the activated‐ester moieties was performed in situ through alkylation reaction with alkylamines to afford monolithic stationary phases with potential reversed‐phase properties. A correlation between the synthesis conditions – composition of the reactive solution – chemical characteristics of the reactive polymer monoliths – nitrogen/NAS content – and the reversed‐phase separation properties of the functionalized monolithic columns – selectivity towards homologous series of akylbenzenes – was clearly established. This finding offers the possibility of adjusting the experimental conditions with respect to the target applications. The monolithic stationary phases with optimized chemical and porous structures were used for the CEC separation of alkylbenzenes, phenols, anilines, organic acids, amino acids, and proteins. The data indicate that depending on the nature of the analytes (charge, hydrophobic/hydrophilic balance, size) reversed‐phase or mixed modes may account for the observed separation.
Structural monitoring in advanced bridge engineering
Authors: Tesar Alexander , Melcer Jozef
Published: October 2007

Dynamic identification and monitoring of bridges are dealt with in this paper. Theoretical, numerical and experimental in situ assessments of the problem are presented. Numerical analysis of the monitoring and testing suggested is based on the adoption of the wave approaches. A structural application in situ on attractive cable‐stayed bridge adopting the monitoring approaches suggested is submitted. Copyright © 2007 John Wiley & Sons, Ltd.
Culture or cult? The mythological nature of occupational therapy
Authors: Kelly Greg , Mcfarlane Heather
Published: October 2007

The willingness of occupational therapists to act on their shared beliefs and values has created knowledge and techniques that have been handed down from generation to generation, and, thus, have entered into what might be called the ‘mythology’ of occupational therapy. These myths arose from a set of shared philosophical assumptions that provided a sense of cultural identity. In the present article the authors compare the occupational therapy process to a mythical hero's journey in which the occupational therapist uses narrative reasoning to guide the client (the hero) through a rite of passage to a kind of rehabilitative rebirth. By structuring therapy as an unfolding story, the occupational therapist creates personal myths for his or her clients. Unfortunately, there is a darker side to this process in which cultural identity distorts into membership of a ‘cult’, wherein expert practitioners become ‘priests’ or ‘monks’ possessing secret knowledge that cannot be readily explained to others, especially those from different cultures. It is argued that, by reflecting on and interacting with other cultures through shared mythologies, occupational therapists can learn to amend their values and beliefs accordingly. Myths could bring a sense of cohesiveness to a culture in which ‘truth’ is seen through these shared mythologies. Copyright © 2007 John Wiley & Sons, Ltd.
Physics Fights in Seoul. Das International Young Physicists' Tournament
Authors: Welzel Manuela , Lehn Rudolf
Published: October 2007

Vom 5. bis 12. Juli 2007 fand in Seoul das International Young Physicists' Tournament statt. Diese Veranstaltung fand in der koreanischen Öffentlichkeit und bei Politikern ein außergewöhnlich großes Interesse. Die gestellten Physikaufgaben verlangen sowohl bei der Vorbereitung als auch beim Turnier selbst intensive Teamarbeit. Das IYPT ist ein gelungenes Beispiel, wie Begabtenförderung aussehen kann.
Der Paranuss‐Effekt
Authors: Ulrich Stephan , Schröter Matthias
Published: October 2007

Granulare Medien, wie Sand, Salz, Kohle oder Kaffeebohnen, lassen sich durch vertikales Schütteln entmischen. In Abhängigkeit von der Schüttelamplitude sammeln sich die größeren Teilchen entweder an der Oberfläche (der sogenannte Paranuss‐Effekt), oder sie sinken nach unten (inverser Paranuss‐Effekt). Mit Experimenten, Computersimulationen und Theorie ist es jüngst gelungen, die zu diesem Verhalten führenden Mechanismen zu identifizieren.
Obsessive Präzision
Authors: Jacobi Manfred
Published: October 2007

Im Jahr 1907 erhielt Albert Abraham Michelson (1852‐1931) als erster amerikanischer Physiker den Nobelpreis für “seine optischen Präzisionsinstrumente und seine damit ausgeführten Untersuchungen auf dem Gebiet der Präzisionsmetrologie und der Spektroskopie.”
An alternate sucrose binding mode in the E203Q Arabidopsis invertase mutant: An X‐ray crystallography and docking study
Authors: Mátrai Janka , Lammens Willem , Jonckheer Abel , Le Roy Katrien , Rabijns Anja , Van den Ende Wim , De Maeyer Marc
Published: October 2007

In the present study, we report on the X‐ray crystallographic structure of a GH32 invertase mutant, (i.e., the Arabidopsis thaliana cell‐wall invertase 1‐E203Q, AtcwINV1‐mutant) in complex with sucrose. This structure was solved to reveal the features of sugar binding in the catalytic pocket. However, as demonstrated by the X‐ray structure the sugar binding and the catalytic pocket arrangement is significantly altered as compared with what was expected based on previous X‐ray structures on GH‐J clan enzymes. We performed a series of docking and molecular dynamics simulations on various derivatives of AtcwINV1 to reveal the reasons behind this modified sugar binding. Our results demonstrate that the E203Q mutation introduced into the catalytic pocket triggers conformational changes that alter the wild type substrate binding. In addition, this study also reveals the putative productive sucrose binding modus in the wild type enzyme. Proteins 2008. © 2007 Wiley‐Liss, Inc.
Influence of oligomerization on the dynamics of G‐protein coupled receptors as assessed by normal mode analysis
Authors: Niv Masha Y. , Filizola Marta
Published: October 2007

The recently discovered impact of oligomerization on G‐protein coupled receptor (GPCR) function further complicates the already challenging goal of unraveling the molecular and dynamic mechanisms of these receptors. To help understand the effect of oligomerization on the dynamics of GPCRs, we have compared the motion of monomeric, dimeric, and tetrameric arrangements of the prototypic GPCR rhodopsin, using an approximate—yet powerful—normal mode analysis (NMA) technique termed elastic network model (ENM). Moreover, we have used ENM to discriminate between putative dynamic mechanisms likely to account for the recently observed conformational rearrangement of the TM4,5‐TM4,5 dimerization interface of GPCRs that occurs upon activation. Our results indicate: (1) significant perturbation of the normal modes (NMs) of the rhodopsin monomer upon oligomerization, which is mainly manifested at interfacial regions; (2) increased positive correlation among the transmembrane domains (TMs) and between the extracellular loop (EL) and TM regions of the rhodopsin protomer; (3) highest interresidue positive correlation at the interfaces between protomers; and (4) experimentally testable hypotheses of differential motional changes within different putative oligomeric arrangements. Proteins 2008. © 2007 Wiley‐Liss, Inc.
Angiotension‐II receptor blockers: their place in hypertension
Authors: Alem Manal , Elliott Henry
Published: October 2007

Angiotensin‐II receptor blockers are now established as a major new class of drugs in the management of hypertension. Our Drug Review considers their properties and efficacy, followed by an analysis of prescription data, sources of further information and the Datafile of available preparations. Copyright © 2007 Wiley Interface Ltd
Enzyme immobilization in latex dispersion coatings for active food packaging
Authors: Nestorson A. , Neoh K. G. , Kang E. T. , Järnström L. , Leufvén A.
Published: October 2007

Carboxylated styrene acrylate latex samples have been functionalized by the immobilization and entrapment of the enzyme glucose oxidase (GOx), which can be used as an oxygen scavenger in food packaging. GOx was covalently immobilized both on the surface of already formed films and on the latex particles in dispersion, as well as entrapped within the polymer matrix. In the latter two cases, polymer films were formed after the enzyme had been added to the latex dispersion. The storage stability of the enzyme and the influence of adding clay were also studied. For a given amount of enzyme, the enzyme immobilized on the film surface showed an enzyme activity about 10 times higher than that of the enzyme present within the polymer matrix. This is probably due to the diffusion limitations of the substrate in the polymer matrix. The films with the enzyme present within the polymer matrix, however, showed a higher total oxygen‐removal capacity than films with the enzyme immobilized on the surface. Entrapped enzyme showed a slightly higher activity than enzyme immobilized in the dispersion due to the negative effect of the activating chemicals used during the immobilization and on conformational constraints upon covalent bonding. Low amounts of clay added to the dispersion decreased the enzyme activity, but with higher amounts of clay the enzyme activity increased, probably because of the increased porosity and thus higher substrate accessibility. The most suitable storage condition for all the enzyme‐containing films was +8°C, which is just above the glass transition temperature of the polymer used. Copyright © 2007 John Wiley & Sons, Ltd.
A simple model for the interaction between water vapour and oxygen transmission in multilayer barrier materials intended for food packaging applications
Authors: Jakobsen Marianne , Risbo Jens
Published: October 2007

The low oxygen permeability of the ethylene‐vinyl alcohol copolymer, EVOH, is outstanding, but is also known to be very sensitive to moisture uptake and cannot be used as a monolayer packaging material. In this paper, theory is presented in order to calculate the average water activity of the EVOH layer at steady state and the corresponding oxygen barrier for different multilayer structures using various polymer types and layer thicknesses. Multilayer materials can be designed for different food packaging applications and storage conditions, in order to keep the relative humidity of the barrier below recommended 75%, by varying the thickness of the outside versus the inside protective layers and/or varying the water vapour transmission rate of the outside versus the inside layer. The conclusion reached is that to retain the optimal barrier properties and thereby the optimal protection of the food, asymmetric multilayer structures are necessary. Copyright ©2007 John Wiley & Sons, Ltd.
Implementation of a constant‐time dynamic storage allocator
Authors: Masmano M. , Ripoll I. , Real J. , Crespo A. , Wellings A. J.
Published: October 2007

This paper describes the design criteria and implementation details of a dynamic storage allocator for real‐time systems. The main requirements that have to be considered when designing a new allocator are concerned with temporal and spatial constraints. The proposed algorithm, called TLSF (two‐level segregated fit), has an asymptotic constant cost,O(1), maintaining a fast response time (less than 200 processor instructions on a x86 processor) and a low level of memory usage (low fragmentation). TLSF uses two levels of segregated lists to arrange free memory blocks and anincomplete searchpolicy. This policy is implemented with word‐size bitmaps and logical processor instructions. Therefore, TLSF can be categorized as a good‐fit allocator. The incomplete search policy is shown also to be a good policy in terms of fragmentation. The fragmentation caused by TLSF is slightly smaller (better) than that caused by best fit (which is one of the best allocators regarding memory fragmentation). In order to evaluate the proposed allocator, three analyses are presented in this paper. The first one is based on worst‐case scenarios. The second one provides a detailed consideration of the execution cost of the internal operations of the allocator and its fragmentation. The third analysis is a comparison with other well‐known allocators from the temporal (number of cycles and processor instructions) and spatial (fragmentation) points of view. In order to compare them, a task model has been presented. Copyright © 2007 John Wiley & Sons, Ltd.
Crosslinking of PVC formulations treated with UV light. II. Color formation and viscoelastic properties
Authors: Benavides R. , Arias G. , Castillo E. L. , Téllez M. M.
Published: October 2007

Two wire coating PVC formulations stabilized with Ca/Zn systems and one stabilized with a traditional lead compound were prepared. All three formulations contained trimethylolpropane trimethacrylate (TMPTMA) as a crosslinking agent and Irgacure 819 as a UV photoinitiator. Small specimens of hot‐pressed materials with 1.0 and 1.5 mm thicknesses were irradiated with UV light for 10 days, while monitoring changes at different time intervals. The presence of TMPTMA in the samples influenced the coloration of the lead‐stabilized formulation, while the others experienced the usual color formation after UV treatment, as seen by Yellowing Index measurements and corroborated by the evaluation of fluorescence spectra. The elastic modulus (E′) determined by DMA was shown to be sensitive to surface changes associated with crosslinking, while the loss modulus (E″) determined by DMA and the complex modulus (E*) obtained by TMA were shown to be sensitive indicators of bulk property changes. J. VINYL ADDIT. TECHNOL., 13:189–194, 2007. © 2007 Society of Plastics Engineers
Synthesis and characterization of a bisbenzotriazole derivative and its application in PVC as an ultraviolet absorber
Authors: Xu Sheyang , Cao Derong , Chen Mingcai
Published: October 2007

A novel ultraviolet (UV) absorber, 5,5′‐disulfide‐bis[2‐(2‐hydroxy‐3,5‐di‐tert‐butylphenyl)‐2Hbenzotriazole] (DSBHTBB) was synthesized. Its structure was characterized by FTIR, NMR, UV, FABMS, and elemental analysis. In comparison with the common commercial benzotriazole UV absorbers, the absorption maximum of DSBHTBB (364 nm) is red shifted by about 20 nm, and the molar extinction coefficient (56,800, in CHCl3) is much greater. With those properties the bisbenzotriazole could be applied as an efficient UV absorber for the protection of polymeric materials and sensitive skin from longer‐wavelength (near‐visible) ultraviolet light. The experimental results showed that DSBHTBB can greatly inhibit the discoloration under irradiation of poly (vinyl chloride) (PVC) containing an organic antimony stabilizer. J. VINYL ADDIT. TECHNOL., 13:195–200, 2007. © 2007 Society of Plastics Engineers
Soil carbon storage, litterfall and CO2 efflux in fertilized and unfertilized larch (Larix leptolepis) plantations
Authors: Kim Choonsig
Published: October 2007

This study evaluated the effects of forest fertilization on the forest carbon (C) dynamics in a 36‐year‐old larch (Larix leptolepis) plantation in Korea. Above‐ and below‐ground C storage, litterfall, root decomposition and soil CO2 efflux rates after fertilization were measured for 2 years. Fertilizers were applied to the forest floor at rates of 112 kg N ha−1 year−1, 75 kg P ha−1 year−1 and 37 kg K ha−1 year−1 for 2 years (May 2002, 2003). There was no significant difference in the above‐ground C storage between fertilized (41.20 Mg C ha−1) and unfertilized (42.25 Mg C ha−1) plots, and the C increment was similar between the fertilized (1.65 Mg C ha−1 year−1) and unfertilized (1.52 Mg C ha−1 year−1) plots. There was no significant difference in the soil C storage between the fertilized and unfertilized plots at each soil depth (0–15, 15–30 and 30–50 cm). The organic C inputs due to litterfall ranged from 1.57 Mg C ha−1 year−1 for fertilized to 1.68 Mg C ha−1 year−1 for unfertilized plots. There was no significant difference in the needle litter decomposition rates between the fertilized and unfertilized plots, while the decomposition of roots with 1–2 mm diameters increased significantly with the fertilization relative to the unfertilized plots. The mean annual soil CO2 efflux rates for the 2 years were similar between the fertilized (0.38 g CO2 m−2 h−1) and unfertilized (0.40 g CO2 m−2 h−1) plots, which corresponded with the similar fluctuation in the organic carbon (litterfall, needle and root decomposition) and soil environmental parameters (soil temperature and soil water content). These results indicate that little effect on the C dynamics of the larch plantation could be attributed to the 2‐year short‐term fertilization trials and/or the soil fertility in the mature coniferous plantation used in this study.
A preliminary report on the vegetation zonation of palsas in the Arctic National Wildlife Refuge, northern Alaska, USA
Authors: Tsuyuzaki Shiro , Sawada Yuki , Kushida Keiji , Fukuda Masami
Published: October 2007

We measured vegetation patterns on palsas with reference to topographic characteristics on the Arctic National Wildlife Refuge, northern Alaska, to obtain benchmark data because of the changes expected from global warming. Vegetation was examined in 60 plots of area 50 cm × 50 cm by five environmental factors: water content in the peat and duff layers, groundwater level, slope angle, depth to frozen surface, and presence of pellets and feces. Three palsas were selected for the survey, and the heights were fewer than 50 cm from the groundwater surface. Based on TWINSPAN and canonical correspondence analysis, we confirmed that clear patterns of vegetation zonation had developed within a 60‐cm difference in water level. Vaccinium vitis‐idaea occurred well on the top areas of palsas, while Carex aquatilis was established on the bottom areas. Sphagnum spp. were established on intermediate locations between V. vitis‐idaea and C. aquatilis. The prime determinant of the vegetation zonation seems to be water content in peat and duff layers rather than water level, although the five factors that we examined interact intricately with each other.
Apoptosis is involved in the senescence of endothelial cells induced by angiotensin II
Authors: Shan Hai‐Yan , Bai Xiao‐Juan , Chen Xiang‐Mei
Published: October 2007

Vascular endothelial cells have a finite cell lifespan and eventually enter an irreversible growth arrest, cellular senescence. The functional changes associated with cellular senescence are thought to contribute to human aging and age‐related cardiovascular disorders, e.g. atherosclerosis. In this study, induction of Angiotensin II (Ang II) promoted a growth arrest with phenotypic characteristics of cell senescence, such as enlarged cell shapes, increased senescence‐associated β‐galactosidase (SA‐β‐gal) positive staining cell, and depressed cell proliferation. Apoptotic changes were increased in senescent cells, with a small subset of the senescent cells showing aberrant morphology such as pronounced nuclear fragmentation or multiple micronuclei. The results suggest cell apoptosis is possibly an important factor in the process of pathologic and physiologic senescence of endothelial cells as well as vascular aging.
Appropriate expression of imprinted genes on mouse chromosome 12 extends development of bi‐maternal embryos to term
Authors: Kawahara Manabu , Wu Qiong , Ferguson-Smith Anne C. , Kono Tomohiro
Published: October 2007

Recently, we reported that the restored regulation of imprinted gene expression from two regions – H19 differentially methylated region (H19‐DMR) and intergenic germline‐derived DMR (IG‐DMR) – is sufficient for accomplishing full‐term development in mice. In the present study, we determined the developmental ability of the bi‐maternal embryos (BMEs) containing the non‐growing oocyte genome with the IG‐DMR deletion (ngΔch12) and fully‐grown (fg) oocyte genome. Foetuses derived from ngΔch12/fg BMEs were alive at E19.5 but could not survive further. Comparison with BMEs derived from Igf2+/− ng/fg genomes suggests that bi‐allelic H19 expression might be involved in foetal development.
DNA variations within the sea urchin Otx gene enhancer
Authors: Yamamoto Takashi , Kawamoto Rie , Fujii Takayoshi , Sakamoto Naoaki , Shibata Tatsuo
Published: October 2007

We performed both intra‐ and interspecific comparisons of the Otx gene in the sea urchin to investigate DNA variations within the enhancer elements. Intraspecific comparisons within Hemicentrotus pulcherrimus showed that indel variations were rare within the Otx enhancer, whereas SNP variations were found uniformly within the whole test region. A similar pattern of DNA variation was observed in comparisons between closely related species. On the other hand, both nucleotide substitution and indel variations were at high levels between distant species. Additionally, the regions corresponding to the Otx enhancer in two related species showed substantial activities during development. Our results suggest the possibility that a stabilizing selection has occurred during the evolution of the Otx gene enhancer in the sea urchin that maintains its expression pattern.
Ophthalmic artery Doppler as a measure of severe pre‐eclampsia
Authors: Diniz A.L.D. , Moron A.F. , dos Santos M.C. , Sass N. , Pires C.R. , Debs C.L.
Published: October 2007

Objective

To identify differences in orbital flow behavior in mild and severe pre‐eclamptic women compared with healthy pregnant women, demonstrated by ophthalmic artery Doppler indexes.

Methods

Ophthalmic artery Doppler indexes of 20 mild and 20 severe pre‐eclamptic women were compared with 51 healthy pregnant women. Right and left eye Doppler index means were evaluated and the resistance index (RI), pulsatility index (PI), peak systolic velocity (PSV), end diastolic velocity (EDV), and peak ratio (PR) were calculated.

Results

Statistically significant differences were observed between PR, PSV, and EDV (P = 0.0009, P = 0.0020, P = 0.0001) ophthalmic artery Doppler in a comparison of women with mild and severe pre‐eclampsia. Statistically significant differences were seen between all Doppler indexes of the study group and healthy pregnant women. Ophthalmic PR, PSV, and EDV were significantly higher in severe pre‐eclamptic cases but other index parameters did not show any difference. An elevation of diastolic and systolic flow occurred when pre‐eclampsia became severe.

Conclusion

Orbital vascular impedance reduction with orbital hyperperfusion was present in severe pre‐eclamptic women compared with mild pre‐eclamptic and healthy pregnant women. Ophthalmic Doppler is a novel parameter that may be useful in the diagnosis of severe pre‐eclampsia.
The effects of iron supplementation on serum copper and zinc levels in pregnant women with high‐normal hemoglobin
Authors: Ziaei Saeideh , Janghorban R. , Shariatdoust Sosan , Faghihzadeh Sofhrate
Published: October 2007

Objective

To evaluate the effect of iron supplementation on serum copper and zinc levels.

Method

In a randomized, double‐blind, placebo‐controlled trial, 66 pregnant women with hemoglobin 13.2 g/dL or greater between the 13th and 18th week of pregnancy were randomized into case and control groups. From the 20th week until the end of pregnancy the case group received one ferrous sulfate tablet containing 50 mg elemental iron daily, while the control group received placebo. Hemoglobin, ferritin, copper, and zinc levels at 24‐28 and 32‐36 weeks of pregnancy were measured and compared.

Results

In the case group, serum copper levels in the second and third trimester were significantly lower than the control group (P < 0.01 and P < 0.001, respectively). Serum zinc levels in the case group in the second and third trimester were also significantly lower than the control group (P < 0.001).

Conclusion

Iron supplementation in pregnant women with hemoglobin greater than 13.2 g/dL reduces serum levels of copper and zinc.
Misoprostol to treat missed abortion in the first trimester
Authors: Gemzell‐Danielsson K. , Ho P.C. , Gómez Ponce de León R. , Weeks A. , Winikoff B.
Published: October 2007

Missed abortion in the first trimester is characterized by the arrest of embryonic or fetal development. The cervix is closed and there is no or only slight bleeding. Ultrasound examination shows an empty gestational sac or an embryo/fetus without cardiac activity. Based on a review of the published literature a single dose of 800 μg vaginal misoprostol may be offered as an effective, safe, and acceptable alternative to the traditional surgical treatment for this indication. Alternatively, 600 μg misoprostol can be administered sublingually. After administration of misoprostol, hospitalization is not necessary and the time to expulsion varies considerably. Bleeding may last for more than 14 days with additional days of light bleeding or spotting. The woman should be advised to contact a provider in case of heavy bleeding or signs of infection. A follow‐up is recommended after 1 to 2 weeks.
Treatment of incomplete abortion and miscarriage with misoprostol
Authors: Blum J. , Winikoff B. , Gemzell‐Danielsson K. , Ho P.C. , Schiavon R. , Weeks A.
Published: October 2007

A literature review was conducted to determine whether misoprostol is an effective treatment for incomplete abortion and, if so, to recommend an appropriate regimen. All English language articles published before October 2007 using misoprostol in at least one of the study arms were reviewed to determine the efficacy of misoprostol when used to treat incomplete abortion in the first trimester. All available unpublished data previously presented at international scientific meetings were also reviewed. Sufficient evidence was found in support of misoprostol as a safe and effective means of non‐surgical uterine evacuation. A single dose of misoprostol 600 μg oral is recommended for treatment of incomplete abortion in women presenting with a uterine size equivalent to 12 weeks gestation.