bluuebunny/crossref_metadata_2025_split huggingface dataset:
Laminin alpha 2 enables glioblastoma stem cell growth
Authors: Lathia Justin D. , Li Meizhang , Hall Peter E. , Gallagher Joseph , Hale James S. , Wu Qiulian , Venere Monica , Levy Emily , Rani M.R. Sandhya , Huang Ping , Bae Eunnyung , Selfridge Julia , Cheng Lin , Guvenc Hacer , McLendon Roger E. , Nakano Ichiro , Sloan Andrew E. , Phillips Heidi S. , Lai Albert , Gladson Candece L. , Bredel Markus , Bao Shideng , Hjelmeland Anita B. , Rich Jeremy N. 
Published: June 2012

AbstractObjective:Glioblastomas (GBMs) are lethal cancers that display cellular hierarchies parallel to normal brain. At the apex are GBM stem cells (GSCs), which are relatively resistant to conventional therapy. Interactions with the adjacent perivascular niche are an important driver of malignancy and self‐renewal in GSCs. Extracellular matrix (ECM) cues instruct neural stem/progenitor cell–niche interactions, and the objective of our study was to elucidate its composition and contribution to GSC maintenance in the perivascular niche.Methods:We interrogated human tumor tissue for immunofluorescence analysis and derived GSCs from tumor tissues for functional studies. Bioinformatics analyses were conducted by mining publicly available databases.Results:We find that laminin ECM proteins are localized to the perivascular GBM niche and inform negative patient prognosis. To identify the source of laminins, we characterized cellular elements within the niche and found that laminin α chains were expressed by nonstem tumor cells and tumor‐associated endothelial cells (ECs). RNA interference targeting laminin α2 inhibited GSC growth and self‐renewal. In co‐culture studies of GSCs and ECs, laminin α2 knockdown in ECs resulted in decreased tumor growth.Interpretation:Our studies highlight the contribution of nonstem tumor cell‐derived laminin juxtracrine signaling. As laminin α2 has recently been identified as a molecular marker of aggressive ependymoma, we propose that the brain vascular ECM promotes tumor malignancy through maintenance of the GSC compartment, providing not only a molecular fingerprint but also a possible therapeutic target. ANN NEUROL 2012;72:766–778
Nitren‐Chemie in der organischen Synthese: noch in den Kinderschuhen?
Authors: Dequirez Geoffroy , Pons Valérie , Dauban Philippe 
Published: June 2012

AbstractStickstoff zählt zu den lebenswichtigen Elementen. Daher wird der Entwicklung von Synthesemethoden zur Einführung dieses Elements in Moleküle besondere Beachtung geschenkt. Nachdem Nitrene seit langem als sehr reaktive, doch unselektive Spezies bekannt waren, konnten sie kürzlich auch zur Bildung von C‐N‐Bindungen eingesetzt werden. Nun sind metallkatalysierte Methoden für die Synthese von Aminen durch Aziridierung von Alkenen oder C‐H‐Aminierung von Alkanen verfügbar. Die hier beschriebenen Ergebnisse zeigen, dass die Nitren‐Chemie für einen größeren Anwendungsbereich in der Synthese nutzbar wird und nicht auf diese beiden Reaktionen beschränkt bleibt.
Application of a new family of organosilicon quadripolymer as a fluid loss additive for drilling fluid at high temperature
Authors: Chu Qi , Luo Pingya , Zhao Qingfeng , Feng Junxiong , Kuang Xubing , Wang Delong 
Published: June 2012

AbstractAn organosilicon quadripolymer of acrylamide (AM), 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid (AMPS), N‐vinylpyrrolidone (NVP) and a kind of organosilicon monomer was synthesized by solution free radical polymerization. The chemical structure of organosilicon quadripolymer was characterized by Fourier transform infrared (FTIR) spectroscopy, and molecular weight distribution was determinate by gel permeation chromatography (GPC) under the best optimum synthesis conditions, which were identified by orthogonal test according to filtrate volume of fresh water‐based drilling fluid. The colloidal properties of the organosilicon quadripolymer drilling fluid were investigated in various media such as fresh‐water, 4.0% salt‐water, and saturated brine based fluid. The results showed that the filtrate volume decreased with the increase of the organosilicon quadripolymer concentration before and after the thermal aging test at 180°C for 16 h, and the filtrate volume after the thermal aging test was larger than that before the thermal aging test, but was smaller than the base fluid. The colloidal properties and the filtrate volume could be controlled effectively at aging temperatures not exceeding 200°C. The organosilicon quadripolymer drilling fluid performance was better than corresponding terpolymer without organosilicon group and shows favorable inhibitive property and was an excellent fluid loss additive for drilling fluid resisting high temperature in deep wells. A possible mechanism is proposed to explain the improvement according to the comparative adsorption experiment. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
An unusual case of cat‐eye syndrome phenotype and extragonadal mature teratoma: Review of the literature
Authors: Tzetis Maria , Stefanaki Kalliopi , Syrmou Areti , Kosma Konstantina , Leze Eleni , Giannikou Krinio , Oikonomakis Vasilis , Sofocleous Christalena , Choulakis Michael , Kolialexi Aggeliki , Makrythanasis Periklis , Kitsiou–Tzeli Sophia 
Published: June 2012

AbstractBACKGROUND Cat‐Eye syndrome (CES) with teratoma has not been previously reported. We present the clinical and molecular findings of a 9‐month‐old girl with features of CES and also a palpable midline neck mass proved to be an extragonadal mature teratoma, additionally characterized by array comparative genomic hybridization (aCGH). RESULTS High resolution oligonucleotide‐based aCGH confirmed that the supernumerary marker chromosome (SMC) derived from chromosome 22, as was indicated by molecular cytogenetic analysis with fluorescence in situ hybridization (FISH). Additionally, aCGH clarified the size, breakpoints, and gene content of the duplication (dup 22q11.1q11.21; size:1.6 Mb; breakpoints: 15,438,946‐17,041,773; hg18). The teratoma tissue was also tested with aCGH, in which the CES duplication was not found, but the analysis revealed three aberrations: del Xp22.3 (108,864‐2788,689; 2.7 Mb hg18), dup Yp11.2 (6688,491‐7340,982; 0.65 Mb, hg18), and dup Yq11.2q11.23 (12,570,853‐27,177,133; 14.61 Mb, hg18). These results indicated 46 XY (male) karyotype of the teratoma tissue, making this the second report of mature extragonadal teratoma in a female neonate, probably deriving from an included dizygotic twin of opposite sex (fetus in fetu). CONCLUSIONS Our findings extend the phenotypic spectrum of CES syndrome, a disorder with clinical variability, pointing out specific dosage‐sensitive genes that might contribute to specific phenotypic features. Birth Defects Research (Part A) 2012. © 2012 Wiley Periodicals, Inc.
Biologically inspired strategy for programmed assembly of viral building blocks with controlled dimensions
Authors: Rego Jennifer M. , Lee Jae‐Hun , Lee David H. , Yi Hyunmin 
Published: June 2012

AbstractFacile fabrication of building blocks with precisely controlled dimensions is imperative in the development of functional devices and materials. We demonstrate the assembly of nanoscale viral building blocks of controlled lengths using a biologically motivated strategy. To achieve this we exploit the simple self‐assembly mechanism of Tobacco mosaic virus (TMV), whose length is solely governed by the length of its genomic mRNA. We synthesize viral mRNA of desired lengths using simple molecular biology techniques, and in vitro assemble the mRNA with viral coat proteins to yield viral building blocks of controlled lengths. The results indicate that the assembly of the viral building blocks is consistent and reproducible, and can be readily extended to assemble building blocks with genetically modified coat proteins (TMV1cys). Additionally, we confirm the potential utility of the TMV1cys viral building blocks with controlled dimensions via covalent and quantitative conjugation of fluorescent markers. We envision that our biologically inspired assembly strategy to design and construct viral building blocks of controlled dimensions could be employed to fabricate well‐controlled nanoarchitectures and hybrid nanomaterials for a wide variety of applications including nanoelectronics and nanocatalysis.
Theoretical Approach Towards the Understanding of Asymmetric Additions of Dialkylzinc to Enals and Iminals Catalysed by [2.2]Paracyclophane‐Based N,O‐Ligands
Authors: Kubas Adam , Bräse Stefan , Fink Karin 
Published: June 2012

AbstractThe 1,2‐ and 1,4‐asymmetric additions of dialkylzinc reagents (ZnMe2 and ZnEt2) to cinnamaldehyde and N‐formylbenzylimine catalysed by [2.2]paracyclophane‐based N,O‐ligands were studied with quantum chemical methods. High level LPNO‐CEPA/1 (local pair natural orbital coupled electron pair approximation 1) calculations were performed to obtain reliable reaction barriers and binding energies. The calculations supported the experimentally observed selectivities. In the reaction, the alkyl transfer takes place on a binuclear zinc complex. Regioselectivity can be traced back to changes in π‐conjugation. Because the less conjugated N‐formylbenzylimine is more flexible, it is better suited for 1,4‐additions. Moreover, bulky ligands were shown to be important for stereoselectivity. The reason is that the tricyclic motif present in the transition states is sterically less hindered in the anti conformation. Based on the LPNO‐CEPA/1 data, a set of popular theoretical methods are validated. Although it was possible to set up a procedure to obtain the stereoselectivities with computationally less demanding methods, this was not possible for the regioselectivity of the reactions.
Luminescence Properties of C‐Diazaborolyl‐ortho‐Carboranes as Donor–Acceptor Systems
Authors: Weber Lothar , Kahlert Jan , Brockhinke Regina , Böhling Lena , Brockhinke Andreas , Stammler Hans‐Georg , Neumann Beate , Harder Rachel A. , Fox Mark A. 
Published: June 2012

AbstractSeven derivatives of 1,2‐dicarbadodecaborane (ortho‐carborane, 1,2‐C2B10H12) with a 1,3‐diethyl‐ or 1,3‐diphenyl‐1,3,2‐benzodiazaborolyl group on one cage carbon atom were synthesized and structurally characterized. Six of these compounds showed remarkable low‐energy fluorescence emissions with large Stokes shifts of 15100–20260 cm−1 and quantum yields (ΦF) of up to 65 % in the solid state. The low‐energy fluorescence emission, which was assigned to a charge‐transfer (CT) transition between the cage and the heterocyclic unit, depended on the orientation (torsion angle, ψ) of the diazaborolyl group with respect to the cage CC bond. In cyclohexane, two compounds exhibited very weak dual fluorescence emissions with Stokes shifts of 15660–18090 cm−1 for the CT bands and 1960–5540 cm−1 for the high‐energy bands, which were assigned to local transitions within the benzodiazaborole units (local excitation, LE), whereas four compounds showed only CT bands with ΦF values between 8–32 %. Two distinct excited singlet‐state (S1) geometries, denoted S1(LE) and S1(CT), were observed computationally for the benzodiazaborolyl‐ortho‐carboranes, the population of which depended on their orientation (ψ). TD‐DFT calculations on these excited state geometries were in accord with their CT and LE emissions. These C‐diazaborolyl‐ortho‐carboranes were viewed as donor–acceptor systems with the diazaborolyl group as the donor and the ortho‐carboranyl group as the acceptor.
Click Mechanochemistry: Quantitative Synthesis of “Ready to Use” Chiral Organocatalysts by Efficient Two‐Fold Thiourea Coupling to Vicinal Diamines
Authors: Štrukil Vjekoslav , Igrc Marina D. , Eckert‐Maksić Mirjana , Friščić Tomislav 
Published: June 2012

AbstractMechanochemical methods of neat grinding and liquid‐assisted grinding have been applied to the synthesis of mono‐ and bis(thiourea)s by using the click coupling of aromatic and aliphatic diamines with aromatic isothiocyanates. The ability to modify the reaction conditions allowed the optimization of each reaction, leading to the quantitative formation of chiral bis(thiourea)s with known uses as organocatalysts or anion sensors. Quantitative reaction yields, combined with the fact that mechanochemical reaction conditions avoid the use of bulk solvents, enabled solution‐based purification methods (such as chromatography or recrystallization) to be completely avoided. Importantly, by using selected model reactions, we also show that the described mechanochemical reaction procedures can be readily scaled up to at least the one‐gram scale. In that way, mechanochemical synthesis provides a facile method to fully transform valuable enantiomerically pure reagents into useful products that can immediately be applied in their designed purpose. This was demonstrated by using some of the mechanochemically prepared reagents as organocatalysts in a model Morita–Baylis–Hillman reaction and as cyanide ion sensors in organic solvents. The use of electronically and sterically hindered ortho‐phenylenediamine revealed that mechanochemical reaction conditions can be readily optimized to form either the 1:1 or the 1:2 click‐coupling product, demonstrating that reaction stoichiometry can be more efficiently controlled under these conditions than in solution‐based syntheses. In this way, it was shown that excellent stoichiometric control by mechanochemistry, previously established for mechanochemical syntheses of cocrystals and coordination polymers, can also be achieved in the context of covalent‐bond formation.
Electrochromatographic Enantioseparation of Amino Acids Using Polybutylmethacrylate‐based Chiral Monolithic Column by Capillary Electrochromatography
Authors: Aydogan Cemil , Denizli Adil 
Published: June 2012

ABSTRACTThis article describes the development of a polybutylmethacrylate‐based monolithic capillary column as a chiral stationary phase. The chiral monolithic column was prepared by polymerization of butyl methacrylate (BMA), ethylene dimethacrylate (EDMA), and N‐methacryloyl‐l‐glutamic acid (MAGA) in the presence of porogens. The porogen mixture included N,N‐dimethyl formamide and phosphate buffer. MAGA was used as a chiral selector. The effect of MAGA content was investigated on electrochromatographic enantioseparation of d,l‐histidine, d,l‐tyrosine, d,l‐phenyl alanine, and d,l‐glutamic acid. The effect of acetonitrile (ACN) content in mobile phase on electro‐osmotic flow was also investigated. It was demonstrated that the poly(BMA‐EDMA‐MAGA) monolithic chiral column can be used for the electrochromatographic enantioseparation of amino acids by capillary electrochromatography (CEC). The mobile phase was ACN/10 mM phosphate buffer (45:55%) adjusted to pH 2.7. It was observed that l‐enantiomers of the amino acids migrated before d‐enantiomers. The separation mechanism of electrochromatographic enantioseparation of amino acids in CEC is discussed. Chirality 24:606–609, 2012. © 2012 Wiley Periodicals, Inc.
3D Hexagonal Mesoporous Silica and Its Organic Functionalization for High CO2 Uptake
Authors: Dutta Arghya , Nandi Mahasweta , Sasidharan Manickam , Bhaumik Asim 
Published: June 2012

AbstractHighly ordered 3D‐hexagonal mesoporous silica HMS‐3 and its vinyl‐ and 3‐chloropropyl‐functionalized analogues HMS‐4 and ‐5, respectively, are synthesized under strongly alkaline conditions at 277 K. Tetraethyl orthosilicate, vinyltrimethoxysilane, and 3‐chloropropyltrimethoxysilane are used as silica sources, and cetyltrimethylammonium bromide as the structure‐directing agent. The 3D‐hexagonal pore structures of HMS‐3, 4‐, and ‐5 were confirmed by powder XRD and high‐resolution TEM studies. Brunauer–Emmett–Teller surface areas of these materials are 1353, 1211, and 603 m2 g−1 for HMS‐3, ‐4, and ‐5, respectively. Among these materials, vinyl‐functionalized mesoporous material HMS‐4 adsorbs the highest CO2 (5.5 mmol g−1, 24.3 wt %) under 3 bar pressure at 273 K. The 3D‐hexagonal pore openings, very high surface area, and cagelike mesopores as well as organic functionalization could be responsible for very high CO2 uptakes of these materials compared to other related mesoporous silica‐based materials.
Automated analysis of flow cytometric data for CD34+ stem cell enumeration using a probability state model
Authors: Herbert Donald J. , Miller David T. , Bruce Bagwell C. 
Published: June 2012

AbstractBackground:Flow Cytometry is widely used for enumeration of hematopoietic stem cell (SC) levels in bone marrow, cord blood, peripheral blood, and apheresis products. The ISHAGE single‐platform gating method is considered by many to be the standard for CD34+ SC enumeration. However, attempts at uniform application of this ISHAGE method have met with only partial success. We propose an automated, multivariate classification approach for SC analysis based on Probability State Modeling™ (PSM). In this study, we compare the results from automated PSM analysis with manual ISHAGE gating analysis as performed by a trained analyst.Methods:A total of 258 samples were assayed on BD FACSCanto II flow cytometers using a stain‐lyse‐no‐wash technique. Populations were defined using CD34, CD45, 7‐AAD, and light scatter. BD TruCount™ bead tubes were used for absolute SC concentrations. A PSM was designed to classify events into beads, debris, intact‐dead cells, and intact‐live SC; run unattended and record results.Results:The ISHAGE and PSM methods show excellent agreement in estimating the concentration of #SC/μL: slope = 1.009, r2 = 0.999. Bland‐Altman Analysis for the SC concentration has an average difference (bias) of 2.018 SC/μL. The 95% confidence interval is from −59.350 to 63.380 SC/μL. The operator‐to‐operator agreement using PSM is perfect: r2 = 1.000.Conclusions:Automated PSM analysis of SC listmode data produces results that agree strongly with ISHAGE gate‐based results. The PSM approach provides higher reproducibility, objectivity, and speed with accuracy at least equivalent to the ISHAGE method. © 2012 International Clinical Cytometry Society
Predictive factors for diabetic foot ulceration: a systematic review
Authors: Monteiro‐Soares M. , Boyko E. J. , Ribeiro J. , Ribeiro I. , Dinis‐Ribeiro M. 
Published: June 2012

SummaryImproving ability to predict and prevent diabetic foot ulceration is imperative because of the high personal and financial costs of this complication. We therefore conducted a systematic review in order to identify all studies of factors associated with DFU and assess whether available DFU risk stratification systems incorporate those factors of highest potential value.We performed a search in PubMed for studies published through April 2011 that analysed the association between independent variables and DFU. Articles were selected by two investigators‐independently and blind to each other. Divergences were solved by a third investigator.A total of 71 studies were included that evaluated the association between diabetic foot ulceration and more than 100 independent variables. The variables most frequently assessed were age, gender, diabetes duration, BMI, HbA1c and neuropathy. Diabetic foot ulceration prevalence varied greatly among studies. The majority of the identified variables were assessed by only two or fewer studies. Diabetic neuropathy, peripheral vascular disease, foot deformity and previous diabetic foot ulceration or lower extremity amputation – which are the most common variables included in risk stratification systems – were consistently associated with diabetic foot ulceration development.Existing diabetic foot ulceration risk stratification systems often include variables shown repeatedly in the literature to be strongly predictive of this outcome. Improvement of these risk classification systems though is impaired because of deficiencies noted, including a great lack of standardization in outcome definition and variable selection and measurement. Copyright © 2012 John Wiley & Sons, Ltd.
Riparian vegetation responses to altered flow regimes driven by climate change in Mediterranean rivers
Authors: Rivaes Rui , Rodríguez‐González Patricia M. , Albuquerque António , Pinheiro António N. , Egger Gregory , Ferreira Maria Teresa 
Published: June 2012

ABSTRACTMediterranean regions are characterized by a large intra‐annual and inter‐annual variability in rainfall and associated hydrological regime patterns. Predictions of changes in climate indicate that mean precipitation and annual temperature will both increase, with a concentration of precipitation and the existence of extended and harsher drought periods with profound implications for river ecosystems. Our aim in this study was to predict the response of Mediterranean riparian vegetation to different climate change scenarios, using a dynamic riparian vegetation model that relates flow regime with riparian vegetation dynamics. In our case study, mapped riparian patches were significantly distinct in between, and altitude, height above water table, patch age and stem diameter were the most important of the factors that distinguished succession phases. A floodplain vegetation model was calibrated and achieved a good strength of agreement between simulated and observed maps. Model results with the expected flow regime under the effect of climate change demonstrate that nonwoody sparsely vegetated areas expand outwards and mature succession patches expand inwards, whereas pioneer and young riparian patches decrease in area. Our results suggest that extreme climatic change in Mediterranean rivers will promote the disappearance of the pioneer and young succession stages of riparian woodlands, thus making efforts to conserve these ecosystems a challenging task. Copyright © 2012 John Wiley & Sons, Ltd.
Tetrafluoroborate Selective Electrodes on the Basis of Cations with Delocalized Charge
Authors: Studenyak Yaroslav , Fershal Maksym , Kushnir Larysa , Gomonnai Alexander V. 
Published: June 2012

AbstractScreening of active substances based on styryl and trimethine cyanine dyes was carried out to prepare tetrafluoroborate ion‐selective electrodes. Correlations between the nature of the organic cation (pKa) and working pH ranges of the sensors were studied. New tetrafluoroborate‐selective PVC membrane electrodes based on an active substance formed by the ion pair of 2‐(n‐ethylcarbazol‐3)‐ethenyl‐1,3,3‐trimethyl‐3H‐indolium and 2‐[3‐(5,6‐dimethyl‐3‐nonyl‐1,3‐benzothiazol‐2(3H)‐ylidene)propenyl]‐5,6‐dimethyl‐3‐nonyl‐1,3‐benzothiazolium with tetrafluoroborate ion were developed. The electrodes are non‐sensitive to pH in the range of 2–8 and can be used for boron determination in acidic media of 6–7 mol L−1 H2SO4. The developed sensor was successfully applied for the determination of B2O3 in CdS(Se) nanocrystal‐doped glasses.