bluuebunny/crossref_metadata_2025 huggingface dataset:
Cooperative Multicomponent Self‐Assembly of Nucleic Acid Structures for the Activation of DNAzyme Cascades: A Paradigm for DNA Sensors and Aptasensors
Authors: Elbaz Johann , Moshe Michal , Shlyahovsky Bella , Willner Itamar
Published: February 2009

Self‐assembly line: In the presence of a DNA analyte or low‐molecular‐weight substrates, multicomponent nucleic acids self‐assemble into cooperatively stabilized functional nanostructures (see scheme) that activate DNAzyme cascades.

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The activation of a DNAzyme cascade by the cooperative self‐assembly of multicomponent nucleic acid structures is suggested as a method for the amplified sensing of DNA, or the specific substrates of aptamers. According to one configuration, the DNA analyte 1 is detected by two tailored nucleic acids 2 and 3 that form a multicomponent supramolecular structure with a ribonucleobase‐containing quasi‐circular DNA 4, but only upon the concomitant hybridization with 1. The resulting supramolecular nucleic acid structure includes the Mg2+‐dependent DNAzyme that cleaves the ribonucleobase site of 4. The cleavage of the quasi‐circular DNA 4 results in the fragmentation of the supramolecular structure and the release of two horseradish peroxidase (HRP) mimicking units that were incorporated in the blocked quasi‐circular DNA 4. The HRP‐mimicking DNAzyme catalyzed the oxidation of 2,2′‐azino‐bis(3‐ethylbenzothiazoline)‐6‐sulfonic acid (ABTS2−) by H2O2 to ABTS.−, and the product provided the colorimetric readout signal for the analyzed DNA. The method enabled the analysis of DNA with a detection limit of 1×10−12 M. Similarly, an analogous DNAzyme cascade was activated by the low‐molecular‐weight substrates, adenosine triphosphate (ATP) or cocaine. This was induced by the self‐assembly of nucleic acids that included fragments of the respective aptamers and the Mg2+‐dependent DNAzyme. Furthermore, nucleic acids consisting of fragments of the aptamers against ATP or cocaine and fragments of the HRP‐mimicking DNAzyme self‐assemble, in the presence of the respective substrates, to the active DNAzyme structure that catalyzes the oxidation of ABTS2− by H2O2 to form the colored product ABTS.−. The resulting product provided the readout signal for the recognition events. The cooperative interaction in the formation of the supramolecular nucleic acid assemblies and the activation of the DNAzymes are discussed.
Chiral separations of some β‐adrenergic agonists and antagonists on AmyCoat column by HPLC
Authors: Ali Imran , Saleem Kishwar , Gaitonde Vinay D. , Aboul‐Enein Hassan Y. , Hussain Iqbal
Published: February 2009

Sixteen β‐adrenergic antagonists namely acebutalol, alprenolol, atenolol, bisoprolol, bopindolol, bufurolol, carazolol, celiprolol, indenolol, metaprolol, nebivolol, oxprenolol, practolol, propranolol, tertalol, and timolol, and two β‐adrenergic agonists namely cimeterol and clenbuterol were resolved on AmyCoat (150 × 46 mm, 3 μm size of silica particle) by using (85:15:0.1, v/v/v), (90:10:0.1, v/v/v), and (95:05:0.1, v/v/v) combinations of n‐heptane, ethanol, and diethylamine solvents, respectively. The flow rates used were 0.5, 1.0, 2.0, and 3.0 ml/min with detection at 225 nm. The values of capacity, separation, and resolution factors ranged from 0.38 to 19.70, 1.08–2.33, and 1.0 and 4.50, respectively. The maximum and minimum resolutions were achieved for celiprolol and bufurolol, respectively. The chiral recognition mechanisms were also discussed. The values of validation parameters were calculated. Chirality 2010. © 2009 Wiley‐Liss, Inc.
Clinical and cost effectiveness of services for early diagnosis and intervention in dementia
Authors: Banerjee Sube , Wittenberg Raphael
Published: February 2009

Background

This paper analyses the costs and benefits of commissioning memory services for early diagnosis and intervention for dementia.

Method

A model was developed to examine potential public and private savings associated with delayed admissions to care homes in England as a result of the commissioning of memory services.

Findings

The new services would cost around £220 million extra per year nationally in England. The estimated savings if 10% of care home admissions were prevented would by year 10 be around £120 million in public expenditure (social care) and £125 million in private expenditure (service users and their families), a total of £245 million. Under a 20% reduction, the annual cost would within around 6 years be offset by the savings to public funds alone. In 10 years all people with dementia will have had the chance to be seen by the new services. A gain of between 0.01 and 0.02 QALYs per person year would be sufficient to render the service cost‐effective (in terms of positive net present value). These relatively small improvements seem very likely to be achievable.

Interpretation

These analyses suggest that the service need only achieve a modest increase in average quality of life of people with dementia, plus a 10% diversion of people with dementia from residential care, to be cost‐effective. The net increase in public expenditure would then, on the assumptions discussed and from a societal perspective, be justified by the expected benefits. This modelling presents for debate support for the development of nationwide services for the early identification and treatment of dementia in terms of quality of life and overall cost‐effectiveness. Copyright © 2009 John Wiley & Sons, Ltd.
Long‐term care and hospital utilisation by older people: an analysis of substitution rates
Authors: Forder Julien
Published: February 2009

Older people are intensive users of hospital and long‐term care services. This paper explores the extent to which these services are substitutes. A small area analysis was used with both care home and (tariff cost‐weighted) hospital utilisation for older people aggregated to electoral wards in England.

Health and social‐care structural equations were specified using a theoretical model. The estimation accounted for the skewed and censored nature of the data. For health utilisation, both a fixed effects instrumental variables GMM model and a generalised estimating equations (GEE) model were fitted, the later on a log dependent variable with predicted values of social care utilisation used to account for endogeneity (bootstrapping was used to derive standard errors). In addition to a GMM model, the social‐care estimation used both two‐part and tobit models (also with predicted health utilisation and bootstrapping).

The results indicate that for each additional £1 spent on care homes, hospital expenditure falls by £0.35. Also, £1 additional hospital spend corresponds to just over £0.35 reduction on care home spend. With these cost substitution effects offsetting, a transfer of resources to care homes is efficient if the resultant outcome gain is greater than the outcome loss from reduced hospital use. Copyright © 2009 John Wiley & Sons, Ltd.
Uncertainty and validation of health economic decision models
Authors: Kim Lois G. , Thompson Simon G.
Published: February 2009

Health economic decision models are based on specific assumptions relating to model structure and parameter estimation. Validation of these models is recommended as an indicator of reliability, but is not commonly reported. Furthermore, models derived from different data and employing different assumptions may produce a variety of results.

A Markov model for evaluating the long‐term cost‐effectiveness of screening for abdominal aortic aneurysm is described. Internal, prospective and external validations are carried out using individual participant data from two randomised trials. Validation is assessed in terms of total numbers and timings of key events, and total costs and life‐years. Since the initial model validates well only internally, two further models are developed that better fit the prospective and external validation data. All three models are then extrapolated to a life‐time horizon, producing cost‐effectiveness estimates ranging from £1600 to £4200 per life‐year gained.

Parameter uncertainty is now commonly addressed in health economic decision modelling. However, the derivation of models from different data sources adds another level of uncertainty. This extra uncertainty should be recognised in practical decision‐making and, where possible, specifically investigated through independent model validation. Copyright © 2009 John Wiley & Sons, Ltd.
Making the most of information‐gathering interviews with children
Authors: Larsson Anneli S. , Lamb Michael E.
Published: February 2009

Because child abuse victims are often the only available sources of information about their experiences, extensive efforts have been made to understand how to maximize their informativeness. There is now broad international consensus regarding optimal interview practices, and broad awareness that children's informativeness increases when interviewers conduct developmentally appropriate interviews with children. In this paper, we (1) summarize current understanding of how children remember, retrieve, and communicate information and (2) discuss ways in which children's memory and reporting can be fostered using techniques designed to help children recount past experiences such as the Cognitive Interview, the Narrative Elaboration Technique, and the National Institute of Child Health and Human Development‐Protocol. Communicative success clearly depends on how well children understand their role and how effectively interviewers take advantage of children's competencies and abilities to help them maximize their informativeness. Unfortunately, agreement regarding ways in which interviews should be conducted has not been paralleled by changes in the way interviews are actually conducted in the field and more attention thus needs to be paid to training and implementation. Copyright © 2008 John Wiley & Sons, Ltd.
Limits of CD133 as a marker of glioma self‐renewing cells
Authors: Clément Virginie , Dutoit Valérie , Marino Denis , Dietrich Pierre‐Yves , Radovanovic Ivan
Published: February 2009

In human gliomas, self‐renewing and tumor‐initiating cells are characterized by the expression marker CD133. Although, widely used, the validity of CD133 is debated as recent data show that CD133+ and CD133− cells share similar stemness and tumorigenic properties. To clarify this “CD133 controversy”, we reexamined the methods of purification and the stem behavior of both CD133 compartments in fresh gliomas and gliomasphere cultures. Using human anti‐CD133‐coupled microbeads and magnetic activated cell sorting, we observed a nonspecific sorting of glioma cells irrespective of their CD133 expression. In contrast, when purified by fluorescence activating cell sorting, a specific expression and enrichment of CD133 was successfully observed in fresh human gliomas and gliomasphere cultures. However, neither the expression of stemness genes nor the long‐term self‐renewal capacities of CD133+ and CD133− cells were significantly different, even after fresh isolation. Altogether, our data show that purification of CD133+ glioma cells using hCD133‐microbeads presents a lack of specificity and demonstrate that the use of CD133 as a unique glioma stem cell marker is likely not sufficient to tag the whole self‐renewing tumor cell reservoir. © 2009 UICC
Gene signatures of pulmonary metastases of renal cell carcinoma reflect the disease‐free interval and the number of metastases per patient
Authors: Wuttig Daniela , Baier Barbara , Fuessel Susanne , Meinhardt Matthias , Herr Alexander , Hoefling Christian , Toma Marieta , Grimm Marc‐Oliver , Meye Axel , Rolle Axel , Wirth Manfred P.
Published: February 2009

Our understanding of metastatic spread is limited and molecular mechanisms causing particular characteristics of metastasis are largely unknown. Herein, transcriptome‐wide expression profiles of a unique cohort of 20 laser‐resected pulmonary metastases (Mets) of 18 patients with clear‐cell renal cell carcinoma (RCC) were analyzed to identify expression patterns associated with two important prognostic factors in RCC: the disease‐free interval (DFI) after nephrectomy and the number of Mets per patient. Differentially expressed genes were identified by comparing early (DFI ≤ 9 months) and late (DFI ≥ 5 years) Mets, and Mets derived from patients with few (≤8) and multiple (≥16) Mets. Early and late Mets could be separated by the expression of genes involved in metastasis‐associated processes, such as angiogenesis, cell migration and adhesion (e.g., PECAM1, KDR). Samples from patients with multiple Mets showed an elevated expression of genes associated with cell division and cell cycle (e.g., PBK, BIRC5, PTTG1) which indicates that a high number of Mets might result from an increased growth potential. Minimal sets of genes for the prediction of the DFI and the number of Mets per patient were identified. Microarray results were confirmed by quantitative PCR by including nine further pulmonary Mets of RCC. In summary, we showed that subgroups of Mets are distinguishable based on their expression profiles, which reflect the DFI and the number of Mets of a patient. To what extent the identified molecular factors contribute to the development of these characteristics of metastatic spread needs to be analyzed in further studies. © 2009 UICC
Investigating FTIR based histopathology for the diagnosis of prostate cancer
Authors: Baker Matthew J. , Gazi Ehsan , Brown Michael D. , Shanks Jonathan H. , Clarke Noel W. , Gardner Peter
Published: February 2009

Prostate cancer is the most common gender specific cancer. The current gold standard for diagnosis, histopathology, is subjective and limited by variation between different pathologists. The diagnostic problems associated with the correct grading and staging of prostate cancer (CaP) has led to an interest in the development of spectroscopic based diagnostic techniques. FTIR microspectroscopy used in combination with a Principal Component Discriminant Function Analysis (PC‐DFA) was applied to investigate FTIR based histopathology for the diagnosis of CaP. In this paper we report the results of a large patient study in which FTIR has been proven to grade CaP tissue specimens to a high degree of sensitivity and specificity. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Post‐transcriptional and post‐translational regulation of PTEN by transforming growth factor‐β1
Authors: Yang Yong , Zhou Feng , Fang Zengyu , Wang Liying , Li Zengxia , Sun Lidong , Wang Can , Yao Wantong , Cai Xiumei , Jin Jiawei , Zha Xiliang
Published: February 2009

PTEN is a critical tumor suppressor gene mutated frequently in various human cancers. Previous studies have showed that PTEN mRNA expression is down‐regulated by TGF‐β1 in various cell lines. In present study, we have found that TGF‐β1 down‐regulates PTEN mRNA and protein expression in a dose‐ and time‐dependent manner in hepatocarcinoma cell line SMMC‐7721. Based on the PTEN promoter dual‐luciferase report assay, we have found that PTEN transcription is not affected by TGF‐β1. By using transcriptional inhibitor actinomycin D (Act D), the turnover rate of PTEN transcripts appeared to be accelerated during TGF‐β1 stimulation, which indicated that down‐regulation of PTEN by TGF‐β1 was post‐transcriptional. What interested us was that transfection of PTEN coding sequence increased TGF‐β1‐induced degradation of PTEN mRNA, suggesting that PTEN coding region was account for TGF‐β1‐mediated down‐regulation of PTEN. In addition, TGF‐β1 down‐regulated PTEN expression was blocked by the TβIR inhibitor SB431542 and the p38 inhibitor SB203580, suggesting Smad and p38 MAPK signal pathways played crucial roles in PTEN down‐regulation via TGF‐β1 stimulation. In this study, we also found TGF‐β1 accelerated down‐regulation of PTEN through the ubiquitin‐proteasome pathway. Collectively, our data clearly demonstrated that TGF‐β1‐mediated down‐regulation of PTEN was post‐transcriptional and post‐translational, depending on its coding sequence, Smad and p38‐MAPK signal pathways were involved in this down‐regulation. J. Cell. Biochem. 106: 1102–1112, 2009. © 2009 Wiley‐Liss, Inc.
Mutually orthogonal graph squares
Authors: Sampathkumar R. , Srinivasan S.
Published: February 2009

A decomposition 𝒢={G1, G2,…,Gs} of a graph G is a partition of the edge set of G into edge‐disjoint subgraphs G1, G2,…,Gs. If Gi≅H for all i∈{1, 2, …, s}, then 𝒢 is a decomposition of G by H. Two decompositions 𝒢={G1, G2, …, Gn} and ℱ={F1, F2,…,Fn} of the complete bipartite graph Kn,n are orthogonal if |E(Gi)∩E(Fj)|=1 for all i,j∈{1, 2, …, n}. A set of decompositions {𝒢1, 𝒢2, …, 𝒢k} of Kn, n is a set of k mutually orthogonal graph squares (MOGS) if 𝒢i and 𝒢j are orthogonal for all i, j∈{1, 2, …, k} and i≠j. For any bipartite graph G with n edges, N(n, G) denotes the maximum number k in a largest possible set {𝒢1, 𝒢2, …, 𝒢k} of MOGS of Kn, n by G. El‐Shanawany conjectured that if p is a prime number, then N(p, Pp+ 1)=p, where Pp+ 1 is the path on p+ 1 vertices. In this article, we prove this conjecture. © 2009 Wiley Periodicals, Inc. J Combin Designs 17: 369–373, 2009
Signatures of DNA double strand breaks produced in irradiated G1 and G2 cells persist into mitosis
Authors: Kato Takamitsu A , Okayasu Ryuichi , Bedford Joel S.
Published: February 2009

We have observed that some of the DNA damage or damage product caused by irradiation of interphase cells persisted throughout the cell cycle, and resulted in the expression of γ‐H2AX foci on the mitotic chromosomes. These mitotic expressions of damage after γ‐irradiation of G1 or G2 phase cells were compared in wild‐type CHO and their DNA repair deficient XR‐1 and UV‐1 cells. γ‐H2AX foci were located on one of the chromatids or on both chromatids as isolocus paired foci. DNA double strand break (DSB) repair deficient XR‐1 cells exhibited greater persistence of γ‐H2AX foci than wild‐type cells when irradiated at G1 phase. Delayed subculture after irradiation significantly reduced the persistence of damage in mitotic cells and the radiosensitivity in wild‐type cells, but this was not the case for XR‐1 cells. Interestingly, UV and crosslinking agents sensitive UV‐1 cells which show similar sensitivity to γ‐irradiation as wild‐type cells by γ‐irradiation, exhibited significantly higher γ‐H2AX persistence at mitosis when they were irradiated in G1‐phase but not in G2‐phase. One interpretation of this is that it is due to DNA damage accumulating at stalled replication forks. As in wild type cells, in delayed subculture after γ‐ray exposure of UV‐1 cells, a reduced number of foci was also seen. Our results suggest that the persistence of γ‐H2AX foci does not always correspond with the radiosensitivities of cells, but rather depends on cells' ability to repair the different kinds of DNA damages. J. Cell. Physiol. 219: 760–765, 2009. © 2009 Wiley‐Liss, Inc.
Fluorescence recovery after photobleaching and photoconversion in multiple arbitrary regions of interest using a programmable array microscope
Authors: Hagen Guy M. , Caarls Wouter , Lidke Keith A. , De Vries Anthony H.B. , Fritsch Cornelia , Barisas B. George , Arndt‐Jovin Donna J. , Jovin Thomas M.
Published: February 2009

Photomanipulation (photobleaching, photoactivation, or photoconversion) is an essential tool in fluorescence microscopy. Fluorescence recovery after photobleaching (FRAP) is commonly used for the determination of lateral diffusion constants of membrane proteins, and can be conveniently implemented in confocal laser scanning microscopy (CLSM). Such determinations provide important information on molecular dynamics in live cells. However, the CLSM platform is inherently limited for FRAP because of its inflexible raster (spot) scanning format. We have implemented FRAP and photoactivation protocols using structured illumination and detection in a programmable array microscope (PAM). The patterns are arbitrary in number and shape, dynamic and adjustable to and by the sample characteristics. We have used multispot PAM–FRAP to measure the lateral diffusion of the erbB3 (HER3) receptor tyrosine kinase labeled by fusion with mCitrine on untreated cells and after treatment with reagents that perturb the cytoskeleton or plasma membrane or activate coexpressed erbB1 (HER1, the EGF receptor EGFR). We also show the versatility of the PAM for photoactivation in arbitrary regions of interest, in cells expressing erbB3 fused with the photoconvertible fluorescent protein dronpa. dronpa. Microsc. Res. Tech., 2009. © 2009 Wiley‐Liss, Inc.
Ultrastructure of motor nerve terminals in the anterior third of wistar rat tongue
Authors: Motoyama Aracy A. , Watanabe Ii‐Sei , Iyomasa Mamie M. , Silva Marcelo C.P. , Sosthines Márcia C.K. , Lopes Marilia Gabriela O. , Guimarães J.P. , Kfoury José R.
Published: February 2009

The nerve terminals of intrinsic muscular fibers of the tongue of adult wistar rats was studied by using silver impregnation techniques, transmission electron microscopy (TEM), and high resolution scanning electron microscopy (HRSEM) to observe the nerve fibers and their terminals. Silver impregnation was done according to Winkelman and Schmit, 1957. For TEM, small blocks were fixed in modified Karnovsky solution, postfixed in 1% buffered osmium tetroxide solution, and embedded in Spurr resin. For HRSEM, the parts were fixed in 2% osmium tetroxide solution with 1/15 M sodium phosphate buffer (pH 7.4) at 4°C for 2 h, according to the technique described by Tanaka, 1989. Thick myelinated nerve bundles were histologically observed among the muscular fibers. The intrafusal nerve fiber presented a tortuous pathway with punctiform terminal axons in clusters contacting the surface of sarcolemma. Several myelinated nerve fibers involved by collagen fibers of the endoneurium were observed in HRSEM in three‐dimensional aspects. The concentric lamellae of the myelin sheath and the axoplasm containing neurofilaments interspersed among the mitochondria were also noted. In TEM, myofibrils, mitochondria, rough endoplasmic reticulum, Golgi's apparatus, and glycogen granules were observed in sarcoplasm. It is also noted that the sarcomeres constituted by myofilaments with their A, I, and H bands and the electron dense Z lines. In areas adjacent to muscular fibers, there were myelinated and unmyelinated nerve fibers involved by endoneurium and perineurium. In the region of the neuromuscular junction, the contact with the sarcolemma of the muscular cell occurs forming several terminal buttons and showing numerous evaginations of the cell membrane. In the terminal button, mitochondria and numerous synaptic vesicles were observed. Microsc. Res. Tech., 2009. © 2009 Wiley‐Liss, Inc.
Ontogeny and phylogeny of the yolk extension in embryonic Cypriniform fishes
Authors: Virta Valerie Christine , Cooper Mark Scott
Published: February 2009

The validity of defining a common phylotypic stage for all vertebrates has been questioned because of variations in embryonic morphological traits between vertebrate classes, as well as variations in embryonic phenotypes between species of the same vertebrate class. To evaluate the evolutionary lability of phylotypic features in vertebrate embryos, we have examined the phylogenetic and ontogenetic origins of the yolk extension—a distinctive morphological trait that is found in the ventrolateral trunk region of cypriniform fish embryos. This posterior axial protrusion, extending from the embryonic yolk ball, is formed in cypriniform fishes by a ventrolateral constriction of the yolk mass during the phylotypic period of development. Using a functional definition of the phylotypic period, a comparative analysis of published literature on developing actinoptyerygian (ray‐finned) fishes reveals that the yolk extension is a shared embryonic trait of the clade Cypriniformes. The yolk extension also appears in several species in two other basal teleostean clades, Characiformes and Anguilliformes. The conservation of the yolk extension in the clade Cypriniformes, as well as its presence in two other basal teleostean clades, supports the hypothesis that the yolk extension is a product of evolutionary transformation. Besides exhibiting evolutionary transformation, the process of yolk extension formation satisfies five other defined criteria for developmental modularity. Thus, it appears that yolk extension ontogenesis is a novel evolutionary, developmental module that has been incorporated into the phylotypic period of certain teleostean lineages. J. Exp. Zool. (Mol. Dev. Evol.) 312B:196–223, 2009. © 2009 Wiley‐Liss, Inc.
Detection and structural features of the βB2‐B3‐crystallin heterodimer by radical probe mass spectrometry (RP‐MS)
Authors: Diemer Hélène , Atmanene Cédric , Sanglier Sarah , Morrissey Bethny , Van Dorsselaer Alain , Downard Kevin M.
Published: February 2009

The predilection of the β‐crystallin B2 subunit to interact with the βB3 subunit rather than self associate is evident by the detection of the βB2‐B3‐crystallin heterodimer by native gel electrophoresis and electrospray ionisation time‐of‐flight (ESI‐TOF) mass spectrometry under non denaturing conditions. The complex has been detected for the first time and its molecular mass is measured to be 47 450 ± 1 Da. Radical probe mass spectrometry (RP‐MS) was subsequently applied to investigate the nature of the heterodimer through the limited oxidation of the subunits in the complex. Two peptide segments of the βB2 subunit and six of the βB3 subunit were found to oxidise, with far greater oxidation observed within the βB3 versus the βB2 subunit. This, and the observation that the oxidation data of βB2 subunit is inconsistent with the structure of the βB2 monomer, demonstrates that the protection of βB2 is conferred by its association with βB3 subunit within the heterodimer where only the residues of, and towards, its N‐terminal domain remain exposed to solvent. The results suggest that the βB2 subunit adopts a more compacted form than in its monomeric form in order for much of its structure to be enveloped by the βB3 subunit within the heterodimer. Copyright © 2009 John Wiley & Sons, Ltd.
Unambiguous characterization and tissue localization of Pru P 3 peach allergen by electrospray mass spectrometry and MALDI imaging
Authors: Cavatorta Valeria , Sforza Stefano , Mastrobuoni Guido , Pieraccini Giuseppe , Francese Simona , Moneti Gloriano , Dossena Arnaldo , Pastorello Elide Anna , Marchelli Rosangela
Published: February 2009

The lipid transfer protein (LTP), Pru p 3, has been identified as the major allergen present in peach, and its sequence obtained by direct amino acid sequencing has been previously reported. However, several sequences, obtained from c‐DNA and available in databases, show differences among them and from the originally proposed structure. In this paper, we report the fast and unambiguous determination of the structure of Pru p 3 protein, extracted from three different varieties of peach, by electrospray ionization mass spectrometry (ESI‐MS), both coupled to single stage (quadrupole) or advanced (FT‐HRMS) analyzers. The structure was identical to one of the cDNA‐derived sequences and different in two positions from the previously reported structure obtained by amino acid sequencing. Moreover, the exclusive localization of the protein in the outer part of the fruits was assessed by Matrix‐Assisted Laser Desorption Ionization Mass Spectrometry Imaging (MALDI MSI). The results reported here demonstrate the full potential of mass spectrometry for rapidly obtaining high quality structural data of relevant food proteins. Copyright © 2009 John Wiley & Sons, Ltd.
High‐frequency transmission through metallic single‐walled carbon nanotube interconnects
Authors: Tahvili M. S. , Jahanmiri S. , Sheikhi M. H.
Published: February 2009

In this paper, high‐frequency transmission behavior of metallic single‐walled carbon nanotube (SWCNT) interconnects is investigated. The SWCNT is assumed to be lying over a doped Si substrate, in a transmission line configuration. A hybrid approach, combining quantum theory with classical distributed‐element model is utilized to predict dynamical performance of the metallic SWCNT as a nano transmission line. Several aspects of high‐frequency performance of such interconnect, including the effect of SWCNT length and substrate doping level, is studied. A novel modification is proposed to take damping mechanisms effect caused by the imperfect conductance of substrate into account. The results show that the impact of limited conductivity of the substrate determines the dynamical behavior of short SWCNTs; whereas in case of long nanotubes, damping effects that arise from scattering mechanisms are dominant. Copyright © 2009 John Wiley & Sons, Ltd.
The application of empirical methods of 13C NMR chemical shift prediction as a filter for determining possible relative stereochemistry
Authors: Elyashberg Mikhail E. , Blinov Kirill A. , Williams Antony J.
Published: February 2009

The reliable determination of stereocenters contained within chemical structures usually requires utilization of NMR data, chemical derivatization, molecular modeling, quantum‐mechanical (QM) calculations and, if available, X‐ray analysis. In this article, we show that the number of stereoisomers which need to be thoroughly verified, can be significantly reduced by the application of NMR chemical shift calculation to the full stereoisomer set of possibilities using a fragmental approach based on HOSE codes. The applicability of this suggested method is illustrated using experimental data published for a series of complex chemical structures. Copyright © 2009 John Wiley & Sons, Ltd.
Sensitivity of MR diffusion measurements to variations in intracellular structure: Effects of nuclear size
Authors: Xu Junzhong , Does Mark D. , Gore John C.
Published: February 2009

Magnetic resonance imaging measurements of the apparent rate of water diffusion in tumors are sensitive to variations in tissue cellularity, which have been shown useful for characterizing tumors and their responses to treatments. However, because of technical limitations on most MRI systems, conventional pulse gradient spin echo (PGSE) methods measure relatively long time scales, during which water molecules may encounter diffusion barriers at multiple spatial scales, including those much greater than typical cell dimensions. As such they cannot distinguish changes on subcellular scales from gross changes in cell density. Oscillating gradient spin echo (OGSE) methods have the potential to distinguish effects on restriction at much shorter time and length scales. Both PGSE and OGSE methods have been studied numerically by simulating diffusion in a three‐dimensional, multicompartment tissue model. The results show that conventional measurements with the PGSE method cannot selectively probe variations over short length scales and, therefore, are relatively insensitive to intracellular structure, whereas results using OGSE methods at moderate gradient frequencies are affected by variations in cell nuclear sizes and can distinguish tissues that differ only over subcellular length scales. This additional sensitivity suggests that OGSE imaging may have significant advantages over conventional PGSE methods for characterizing tumors. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Measurement of apparent cell radii using a multiple wave vector diffusion experiment
Authors: Weber T. , Ziener C. H. , Kampf T. , Herold V. , Bauer W. R. , Jakob P. M.
Published: February 2009

It had been previously shown that an idealized version of the two‐wave‐vector extension of the NMR pulsed‐field‐gradient spin echo diffusion experiment can be used to determine the apparent radius of geometries with restricted diffusion. In the present work, the feasibility of the experiment was demonstrated in an NMR imaging experiment, in which the apparent radius of axons in white matter tissue was determined. Moreover, numerical simulations have been carried out to determine the reliability of the results. For small diffusion times, the radius is systematically underestimated. Larger gradient area, finite length gradient pulses, and a statistical distribution of radii within a voxel all have a minor influence on the estimated radius. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Uncertainty analysis of complex structural systems
Authors: Schuëller G. I. , Pradlwarter H. J.
Published: February 2009

In this paper methods for uncertainty propagation for complex structural systems are discussed. Only a limited class of methods is available for this purpose. It is shown that only numerical procedures allow the uncertainty assessment and reliability estimation of such systems. In particular, the perturbation procedure, the Karhunen–Loève reduction scheme, the polynomial chaos expansion, direct and advanced Monte Carlo simulation (MCS), as well as random matrix theory meet these requirements. It is shown that advanced MCS procedures proved to be the most versatile approach. Copyright © 2009 John Wiley & Sons, Ltd.
A partitioned model for fluid–structure interaction problems using hexahedral finite elements with one‐point quadrature
Authors: Braun Alexandre Luis , Awruch Armando Miguel
Published: February 2009

A partitioned numerical model for fluid–structure interaction analysis of incompressible flows and structures with geometrically non‐linear behavior is presented in this work. The flow analysis is performed considering the well‐known Navier–Stokes equations for Newtonian fluids and the continuity equation, obtained from the pseudo‐compressibility hypothesis. An explicit two‐step Taylor‐Galerkin scheme is employed in the time discretization procedure of the system of governing equations, which is expressed in terms of an arbitrary Lagrangean‐Eulerian description. The structural subsystem is analyzed using a geometrically non‐linear elastic model and the respective equation of motion is discretized in the time domain employing the Generalized‐α scheme. Fluid–structure coupling is taken into account regarding a new energy‐conserving partitioned scheme with non‐linear effects, which is accomplished by enforcing equilibrium and kinematical compatibility conditions at the solid–fluid interface. Non‐matching meshes and subcycling are also considered in the present model. The finite element method is employed for spatial discretizations using eight‐node hexahedral elements with one‐point integration in both fields. Some numerical examples are simulated in order to demonstrate the applicability of the proposed formulation. Copyright © 2009 John Wiley & Sons, Ltd.
Preparation and applications of novel fluoroalkyl end‐capped vinyltrimethoxysilane oligomer/hydroxyapatite nanocomposites
Authors: Takashima Hiroki , Iwaki Ken‐ichi , Takishita Katsuhisa , Sawada Hideo
Published: February 2009

Novel fluoroalkyl end‐capped vinyltrimethoxysilane oligomer/hydroxyapatite (HAp) nanocomposites were prepared by the reaction of calcium nitrate tetrahydrate and phosphoric acid in the presence of the corresponding oligomer. These fluorinated oligomer/HAp composites thus obtained are nanometer size‐controlled fine particles (83–173 nm), and were found to exhibit good dispersibility in methanol, ethanol, and isopropyl alcohol. These fluorinated HAp nanocomposites were applied to the surface modification of glass and poly(methyl methacrylate) (PMMA) to exhibit good hydro‐ and oleophobic characteristics imparted by fluorine on their surface. In addition, the surface structural changes of the modified polyethylene terephtalate and PMMA films treated with these fluorinated nanocomposites before and after soaking in a simulated body fluid (SBF) were analyzed by using SEM, XRD, and EDX to observe the formation of spherical HAp deposits on the surface. Copyright © 2009 John Wiley & Sons, Ltd.
Contemporary polysilane synthesis and functionalisation
Authors: Koe Julian
Published: February 2009

This paper highlights recent progress and understanding in the synthesis and functionalisation of polysilanes prepared by Wurtz‐type alkali metal‐mediated reductive coupling of dichlorosilanes. Copyright © 2009 Society of Chemical Industry
Switching the conformational behaviour of poly(N‐isopropyl acrylamide)
Authors: Rimmer Stephen , Soutar Ian , Swanson Linda
Published: February 2009

In this review we present data highlighting the power and versatility of luminescence spectroscopy in the study of the conformational behaviour of poly(N‐isopropyl acrylamide) (PNIPAM). PNIPAM shows a lower critical solution temperature (LCST) in aqueous solution at 32 °C. Fluorescence time‐resolved anisotropy measurements (TRAMS) have confirmed that a conformational change occurs from an expanded open chain to a globular structure at the LCST, which forms the basis of phase separation observed for semi‐dilute concentrations. The coiled conformation can solubilise low‐molar‐mass species as revealed by the spectral profile of pyrene and is extremely protective: intersystem crossing to the triplet manifold can be enhanced by use of a heavy‐atom promoter (bromostyrene) copolymerised with NIPAM and trace levels of acenaphthylene allowing generation of phosphorescence at temperatures as high as 50 °C in aqueous solution. Manipulation of the conformational switch of PNIPAM is possible via simple free radical copolymerisation. However, a reduction in the magnitude of the transition occurs, which has an impact on the solubilisation properties of the resultant copolymers. Alternative strategies are suggested to overcome this problem: synthesis of graft copolymers allows fine‐tuning of the thermal response whilst maintaining the magnitude of the transition as revealed by TRAMS. Copyright © 2009 Society of Chemical Industry
Thermal behaviour of poly(lactic acid) in contact with compressed carbon dioxide
Authors: Yu Long , Liu Hongsheng , Dean Katherine
Published: February 2009

BACKGROUND: The thermal behaviour of poly(lactic acid) (PLA) in contact with compressed CO2 was studied using high‐pressure differential scanning calorimetry. In particular, the effect of annealing below and above the glass transition temperature (Tg) on the glass transition, cold crystallization and melting temperatures was studied systematically as a function of annealing time and pressure.

RESULTS: The effect of compressed CO2 on the thermal properties of PLA is time dependent. Annealing below Tg decreases the temperature and enthalpy of cold crystallization. Similar, but more evident, behaviours are observed when annealing above Tg. Crystallization temperature and enthalpy during cooling decrease with increasing pressure, and the peak is narrower.

CONCLUSION: Annealing PLA in the presence of compressed CO2 accelerates cold crystallization, but retards crystallization during cooling. Copyright © 2009 Society of Chemical Industry
Anionic triphenylamine‐ and fluorene‐based conjugated polyelectrolyte as a hole‐transporting material for polymer light‐emitting diodes
Authors: Shi Wei , Wang Lei , Huang Fei , Liu Ransheng , Yang Wei , Cao Yong
Published: February 2009

BACKGROUND: Hole‐transport layers (HTLs) play a crucial role in multilayer polymeric light‐emitting diodes (PLEDs) for the achievement of satisfactory device performance. During the fabrication of multilayer PLEDs via solution processing, the fabricated HTLs encounter the risk of erosion during the film‐forming process of subsequent emitting layers (EMLs). In contrast to the widely investigated crosslinkable HTLs, much less attention has been paid to the preparation of polar‐solvent‐soluble HTLs, which is a straightforward solution to overcome the interfacial mixing between HTLs and EMLs during solution processing.

RESULTS: Alternating triphenylamine‐ and fluorene‐based anionic copolymer poly[9,9‐bis(4′‐sulfonatobutyl)fluorene‐alt‐N‐(p‐trifluoromethyl)phenyl‐4,4′‐diphenylamine]sodium salt (PFT‐CF3) was synthesized via a palladium‐catalyzed Suzuki coupling reaction. This polyelectrolyte is soluble only in polar solvents such as methanol, dimethylformamide and dimethylsulfoxide rather than in non‐polar solvents such as toluene, chloroform and xylene. The relatively high HOMO (−5.22 eV) and LUMO (−2.26 eV) levels of this polymer endow it simultaneously with good hole‐transporting and electron‐blocking capabilities. The performance of red‐, green‐ and blue‐emitting devices utilizing this polyelectrolyte as HTL was investigated.

CONCLUSION: The anionic conjugated polyelectrolyte based on triphenylamine and fluorene, PFT‐CF3, can serve as a promising hole‐transporting/electron‐blocking layer in multilayer PLEDs. Copyright © 2009 Society of Chemical Industry
Hydroxyalkoxy derivatives of oxamic acid: polyol substrates for polyurethane foams
Authors: Zarzyka‐Niemiec Iwona
Published: February 2009

BACKGROUND: The work reported aimed at obtaining hydroxyalkoxy derivatives containing oxalamidoester groups starting from oxamic acid (OA) substrate. These derivatives were then used for the synthesis of polyurethane foams.

RESULTS: The hydroxyalkoxy derivatives were obtained by reaction of OA with 6 to 15 molar excess of ethylene carbonate (1,3‐dioxolane‐2‐one) or propylene carbonate (4‐methyl‐1,3‐dioxolane‐2‐one). The products obtained have good thermal stability and possess suitable physical properties for use as substrates for foamed polyurethanes.

CONCLUSION: The rigid polyurethane foams obtained from the hydroxyalkoxy derivatives of OA possess enhanced thermal stability and good mechanical properties in comparison with traditional polyurethane foams. Copyright © 2009 Society of Chemical Industry
Cytoskeleton‐associated proteins are enriched in human embryonic‐stem cell‐derived neuroectodermal spheres
Authors: Chae Jung‐Il , Kim Janghwan , Woo Sun‐Mi , Han Hyo‐Won , Cho Young Keun , Oh Keon‐Bong , Nam Ki‐Hoan , Kang Yong‐Kook
Published: February 2009

The ability to generate neural lineages from human embryonic stem cells (hESCs) in a controlled manner would further investigation of human neurogenesis and development of potential cell therapeutic applications to treat neurological diseases; however, generating such neural stem cells (NSCs) remains a challenge. In an attempt to characterize the cellular mechanisms involved in hESC differentiation into neuroprogenitor cells, we performed 2‐DE using protein extracts from hESC‐derived embryoid bodies (EBs) and neuroectodermal spheres (NESs) bearing neuroprogenitors. Of 47 differentially expressed protein spots, 28 nonredundant spots were shown to be upregulated in the NESs; these protein spots included neurogenesis‐related proteins (TAF1, SEPT2, NPH3, and CRABP), as expected. Interestingly, 6 of these 28 protein spots were cytoskeleton‐associated proteins (CSAP) such as Fascin‐1, Cofilin‐1, and Stathmin‐1. Western‐blot analyses confirmed the increased levels of these proteins in the NESs. Furthermore, immunostaining analysis showed that both Fascin‐1 and Stathmin‐1 were preferentially expressed in the inner rims of neural rosettes, which are characteristic features of neuroprogenitors in culture. We also confirmed prominent expression of Fascin‐1 in (sub‐)ventricular zone in E15.5 mouse fetal brain. Our results suggest that, in addition to the induction of those genes involved in neural development, hESC differentiation into the NES is associated with a marked reorganization of the cellular cytoskeleton.
Proteome of synaptosome‐associated proteins in spinal cord dorsal horn after peripheral nerve injury
Authors: Singh Om V. , Yaster Myron , Xu Ji‐Tian , Guan Yun , Guan Xiaowei , Dharmarajan Arun M. , Raja Srinivasa N. , Zeitlin Pamela L. , Tao Yuan‐Xiang
Published: February 2009

Peripheral nerve injury may lead to neuroadaptive changes of cellular signals in spinal cord that are thought to contribute to central mechanisms underlying neuropathic pain. Here we used a 2‐DE‐based proteomic technique to determine the global expression changes of synaptosome‐associated proteins in spinal cord dorsal horn after unilateral fifth spinal nerve injury (SNI). The fifth lumbar dorsal horns ipsilateral to SNI or sham surgery were harvested on day 14 post‐surgery, and the total soluble and synaptosomal fractions were isolated. The proteins derived from the synaptosomal fraction were resolved by 2‐DE. We identified 27 proteins that displayed different expression levels after SNI, including proteins involved in transmission and modulation of noxious information, cellular metabolism, membrane receptor trafficking, oxidative stress, apoptosis, and degeneration. Six of the 27 proteins were chosen randomly and further validated in the synaptosomal fraction by Western blot analysis. Unexpectedly, Western blot analysis showed that only one protein in the total soluble fraction exhibited a significant expression change after SNI. The data indicate that peripheral nerve injury changes not only protein expression but also protein subcellular distribution in dorsal horn cells. These changes might participate in the central mechanism that underlies the maintenance of neuropathic pain.
Hydrolytic stability and high Tg of polyimides derived from the novel 4,9‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl]‐diamantane dianhydride
Authors: Chern Yaw‐Terng , Wang Jane‐Jen
Published: February 2009

This work reports the synthesis and characterization of diamantane‐based polyimides obtained from 4,9‐bis[4(3,4‐dicarboxyphenoxy)phenyl]diamantane dianhydride and various aromatic diamines. Interestingly, the diamantane‐based polyimides were very stable to hydrolysis. This novel polyimide exhibits a low dielectric constant (2.65–2.77), low moisture absorption (<0.67%), good solubility, high Tg and unusually high thermal stability. Dynamic mechanical analysis (DMA) reveals that the diamantane‐based polyimides have high Tg ranging from 281 to 379 °C. The high‐temperature β1 subglass transition around 285 °C was observed in polyimide 6a derived from 2,2′‐bis(trifluoromethyl)benzidine. This class of novel diamantane‐based polyimide is very promising for electronic applications, because of its good mechanical properties, good thermal stability, low dielectric constant, excellent hydrolytic resistance, and low moisture absorption. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1673–1684, 2009
Effect of gamma radiation on fluoropolymers
Authors: Contreras‐Garcia A. , Bucio E. , León‐c F. , Booth C. J. , Cassidy P. E.
Published: February 2009

A series of fluoropolymer films were synthesized by reacting several bisphenol monomers with 1,3‐bis(1,1,1,3,3,3‐hexafluoro‐2‐pentafluorophenyl methoxy‐2‐propyl)benzene via a nucleophilic aromatic substitution to form polyethers. The bisphenols used included two diphenol‐substituted spirodilactams (SDL; aliphatic and aromatic), biphenol, bisphenol A, bisphenol AF, bisphenol O, and bisphenol F to form seven different polymers. Polymers were irradiated by a Gamma beam 651‐PT at a dose rate of 10.5 kGy/h; the absorbed dose in each film was varied between 300 and 1000 kGy. The effect on the chemical structure upon radiation was studied by DSC, TGA, FTIR‐ATR, and NMR after and before irradiation. Thermal analysis showed a lessened thermal stability and a lower Tg after irradiation. Further, irradiation caused a decrease in molecular weight as a result of cleavage of sp3 bonds. These data allowed calculation of the radiochemical yield scission (Gs) for each of these polymers. The SDL aromatic system proved the most radiation‐resistant. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1617–1626, 2009