bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interplay of anionic charge, poly(ethylene glycol), and iodinated tyrosine incorporation within tyrosine‐derived polycarbonates: Effects on vascular smooth muscle cell adhesion, proliferation, and motility
Authors: Johnson Patrick A. , Luk Arnold , Demtchouk Aleksey , Patel Hiral , Sung Hak‐Joon , Treiser Matthew D. , Gordonov Simon , Sheihet Larisa , Bolikal Das , Kohn Joachim , Moghe Prabhas V. 
Published: July 2009

AbstractRegulation of smooth muscle cell adhesion, proliferation, and motility on biomaterials is critical to the performance of blood‐contacting implants and vascular tissue engineering scaffolds. The goal of this study was to examine the underlying substrate‐smooth muscle cell response relations, using a selection of polymers representative of an expansive library of multifunctional, tyrosine‐derived polycarbonates. Three chemical components within the polymer structure were selectively varied through copolymerization: (1) the content of iodinated tyrosine to achieve X‐ray visibility; (2) the content of poly(ethylene glycol) (PEG) to decrease protein adsorption and cell adhesivity; and (3) the content of desaminotyrosyl‐tyrosine (DT), which regulates the rate of polymer degradation. Using quartz crystal microbalance with dissipation, we quantified differential serum protein adsorption behavior because of the chemical components DT, iodinated tyrosine, and PEG: increased PEG content within the polymer structure progressively decreased protein adsorption but the simultaneous presence of both DT and iodinated tyrosine reversed the effects of PEG. The complex interplay of these components was next tested on the adhesion, proliferation, and motility behavior cultured human aortic smooth muscle cells. The incorporation of PEG into the polymer reduced cell attachment, which was reversed in the presence of iodinated tyrosine. Further, we found that as little as 10% DT content was sufficient to negate the PEG effect in polymers containing iodinated tyrosine, whereas in non‐iodinated polymers, the PEG effect on cell attachment was reversed. Cross‐functional analysis of motility and proliferation revealed divergent substrate chemistry related cell response regimes. For instance, within the series of polymers containing both iodinated tyrosine and 10% of DT, increasing PEG levels lowered smooth muscle cell motility without a change in the rate of cell proliferation. In contrast, for non‐iodinated tyrosine and 10% of DT, increasing PEG levels increased cell proliferation significantly while reducing cell motility. Clearly, the polycarbonate polymer library offers a sensitive platform to modulate cell adhesion, proliferation, and motility responses, which, in turn, may have implications for controlling vascular remodeling in vivo. Additionally, our data suggests unique biorelevant properties following the incorporation of iodinated subunits in a polymeric biomaterial as a potential platform for X‐ray visible devices. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010
Mechanical and cell viability properties of crosslinked low‐ and high‐molecular weight poly(ethylene glycol) diacrylate blends
Authors: Mazzoccoli Jason P. , Feke Donald L. , Baskaran Harihara , Pintauro Peter N. 
Published: July 2009

AbstractThere is a strong need for tissue engineering scaffolds that are mechanically robust, exhibit good biocompatibility, and can be made from readily available materials. To this end, blends of commercially available poly(ethylene glycol) diacrylate (PEGDA) with molecular weights of 400 and 3400 were UV‐crosslinked at total polymer concentrations that varied systematically from 20 to 40 wt %. The compressive strength and cell viability were determined for each PEGDA mixture. The compressive modulus of the blends was maximized when the weight percent ratio PEGDA3400/400 was about 40/60, with the compressive strength reaching 1.7 MPa. Cell viability results with a LIVE/DEAD fluorescence assay show an average viability of ∼80% at a total PEGDA concentration of 20 wt % for all blends. Increasing the total polymer concentration increased the compressive modulus of a polymer, but adversely affected cell viability for all the PEGDA blend compositions. The blend composition affected the mechanical behavior of the discs, where a higher degree of crosslinking was achieved by increasing the concentration of shorter chained PEGDA400, whereas elasticity was gained by incorporating longer chained PEGDA3400 into the blends. These results can be exploited for use in tissue engineering applications, where a mechanically robust scaffold is advantageous. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010
Co‐activator activator (CoAA) prevents the transcriptional activity of Runt domain transcription factors
Authors: Li Xiaodong , Hoeppner Luke H. , Jensen Eric D. , Gopalakrishnan Rajaram , Westendorf Jennifer J. 
Published: July 2009

AbstractRunx proteins are essential for a number of developmental processes and are aberrantly expressed in many human cancers. Runx factors bind DNA and co‐factors to activate or repress genes crucial for bone formation, hematopoiesis, and neuronal development. Co‐activator activator (CoAA) is a nuclear protein that regulates gene expression, RNA splicing and is overexpressed in many human tumors. In this study, we identified CoAA as a Runx2 binding protein. CoAA repressed Runx factor‐dependent activation of reporter genes in a histone deacetylase‐independent manner. CoAA also blocked Runx2‐mediated repression of the Axin2 promoter, a novel Runx target gene. The carboxy‐terminus of CoAA is essential for binding the Runt domains of Runx1 and Runx2. In electophoretic mobility shift assays, CoAA inhibited Runx2 interactions with DNA. These data indicate that CoAA is an inhibitor of Runx factors and can negate Runx factor regulation of gene expression. CoAA is expressed at high levels in human fetal osteoblasts and osteosarcoma cell lines. Suppression of CoAA expression by RNA interference reduced osteosarcoma cell viability in vitro, suggesting that it contributes to the proliferation and/or survival of osteoblast lineage cells. J. Cell. Biochem. 108: 378–387, 2009. © 2009 Wiley‐Liss, Inc.
Assessment of “grading” with Ki‐67 and c‐kit immunohistochemical expressions may be a helpful tool in management of patients with flat epithelial atypia (FEA) and columnar cell lesions (CCLs) on core breast biopsy
Authors: Tomasino Rosa M. , Morello Vincenza , Gullo Arianna , Pompei Giancarlo , Agnese Valentina , Russo Antonio , Rinaldi Gaetana 
Published: July 2009

AbstractIt is essential to reach a better understanding of “flat epithelial atypia/columnar cell lesions” (FEA/CCLs) in breast core biopsies. Our aim was to explore their biological nature, in order to predict the likelihood of an upgrade to carcinoma. “Cytological grading” has been specially focused, in view of its possible utility in the choice of management. One hundred thirty of a total of 900 cases core needle (CN)/vacuum‐assisted biopsies (VABs), with diagnoses of “hyperplasia” and “atypia” were retrospectively re‐evaluated. Pathological findings of further excision biopsies (FEBs) performed in 40/75 patients with follow‐up were compared with the previous diagnoses. In all cases, both Ki‐67 and c‐kit immunoreactivities were explored and compared with both normal breast tissues and subsequently documented cancers, with special reference to the hyperplastic FEA/CCLs, with “mild” atypia (FEA/CCHAm). Sixteen cases were re‐diagnosed as “usual ductal hyperplasia” (UDH), 60 as “columnar cell hyperplasia” (CCH), and 54 as FEA/CCHA, 30 of which FEA/CCHAm and 24 FEA/CCHAh (with high atypia). Significantly, the Ki‐67 index proved to be on the increase and c‐kit expression on the decrease in FEA/CCHA lesions, mainly in the FEA/CCHAh group and in the subsequently observed cancers, compared with either benign tissues or the FEA/CCH cases. It was also significant that most of the carcinomas were found in FEBs within the FEA/CCHAh group. In this study cytological grading, together with Ki‐67 and c‐kit indices, proved to be helpful in FEA/CCLs evaluation. With regard to FEA/CCHAm lesions, an adequate surveillance appears to be a more appropriate management tool than FEB, as a result of their biological nature and behavior. J. Cell. Physiol. 221: 343–349, 2009. © 2009 Wiley‐Liss, Inc.
Functional role of aquaglyceroporin 7 expression in the pancreatic beta‐cell line BRIN‐BD11
Authors: Delporte C. , Virreira M. , Crutzen R. , Louchami K. , Sener A. , Malaisse W.J. , Beauwens R. 
Published: July 2009

AbstractBoth mouse and rat pancreatic islet β‐cells were recently found to express aquaglyceroporin 7 (AQP7). In the present study, the expression and role of AQP7 in the function of BRIN‐BD11 cells were investigated. AQP7 mRNA and protein were detected by RT‐PCR and Western blot analysis, respectively. In an isoosmolar medium, the net uptake of [2‐3H]glycerol displayed an exponential time course reaching an equilibrium plateau value close to its extracellular concentration. Within 2 min of incubation in a hypotonic medium (caused by a 50 mM decrease in NaCl concentration), the [2‐3H]glycerol uptake averaged 143.2 ± 3.8% (n = 24; P < 0.001) of its control value in isotonic medium, declining thereafter consistently with previously demonstrated volume regulatory decrease. When isoosmolarity was restored by the addition of 100 mM urea to the hypotonic medium, [2‐3H]glycerol uptake remained higher (112.1 ± 2.8%, n = 24; P < 0.001) than its matched control under isotonic conditions, indicating rapid entry of urea and water. Insulin release by BRIN‐BD11 cells was 3 times higher in hypotonic than in isotonic medium. When glycerol (100 mM) or urea (100 mM) were incorporated in the hypotonic medium, the insulin release remained significantly higher than that found in the control isotonic medium, averaging respectively 120.2 ± 4.2 and 107.0 ± 3.8% of the paired value recorded in the hypotonic medium. These findings document the rapid entry of glycerol and urea in BRIN‐BD11 cells, likely mediated by AQP7. J. Cell. Physiol. 221: 424–429, 2009. © 2009 Wiley‐Liss, Inc.
Complex wear measurement on thin coatings by the cratering method
Authors: Bemporad E. , Comis E. , Sebastiani M. , Carassiti F. , Palumbo B. 
Published: July 2009

AbstractBall cratering and rotating wheel tests are useful techniques for abrasive wear resistance evaluation of thin coatings.Nevertheless, such techniques involve significant experimental errors, coming from equipment deficiencies and changes in wear response depending on test parameters.In case of rotating wheel test, common instrumental errors are: geometry‐induced errors (curved or non‐horizontal sample surface), alignment errors (misalignment between ball/wheel rotation axis and sample stage) and optical measurement errors.In the present paper, errors due to crater dimension detection system (penetration depth or crater diameter) and equipment deficiencies (rotating axes misalignment and sample slope) were numerically analysed.A general expression for volume calculation was obtained, considering axes misalignment and sample slope, and experimentally validated by wear tests on Ti/TiN CAE‐PVD coatings and profilometer abraded volumes measurement.Results showed that axes misalignment and sample slope involve considerable errors in wear coefficient evaluation. However, errors can be corrected by the use of obtained expressions. Copyright © 2009 John Wiley & Sons, Ltd.
Polymerizable Well‐Defined Oligo(thiophene amide)s and their ROMP Block Copolymers
Authors: Hilf Stefan , Klos Johannes , Char Kookheon , Woo Heeje , Kilbinger Andreas F. M. 
Published: July 2009

AbstractWe report the synthesis of conjugated thiophene amide oligomers that constitute a new class of chromophores with potential for optoelectronic applications. The synthesis of defined norbornene‐substituted oligothiophene amides using conventional coupling chemistry is described. Their electronic properties depend on the degree of oligomerization as UV/Vis and fluorescence spectroscopy demonstrate. A significant red shift in the spectra upon an increase in the oligomer length evidences conjugation of the thiophene rings via the amide linkages. ROMP of the norbornene‐substituted oligomers gives homopolymers and block‐copolymers with a solubilizing second block. The amphiphilic character of the block copolymers is used to study micellization and bulk self‐organization.magnified image
Numerical and in vivo validation of fast cine displacement‐encoded with stimulated echoes (DENSE) MRI for quantification of regional cardiac function
Authors: Feng Li , Donnino Robert , Babb James , Axel Leon , Kim Daniel 
Published: July 2009

AbstractQuantitative assessment of regional cardiac function can improve the accuracy of detecting wall motion abnormalities due to heart disease. While recently developed fast cine displacement‐encoded with stimulated echoes (DENSE) MRI is a promising modality for the quantification of regional myocardial function, it has not been validated for clinical applications. The purpose of this study, therefore, was to validate the accuracy of fast cine DENSE MRI with numerical simulation and in vivo experiments. A numerical phantom was generated to model physiologically relevant deformation of the heart, and the accuracy of fast cine DENSE was evaluated against the numerical reference. For in vivo validation, 12 controls and 13 heart‐disease patients were imaged using both fast cine DENSE and myocardial tagged MRI. Numerical simulation demonstrated that the echo‐combination DENSE reconstruction method is relatively insensitive to clinically relevant resonance frequency offsets. The strain measurements by fast cine DENSE and the numerical reference were strongly correlated and in excellent agreement (mean difference = 0.00; 95% limits of agreement were 0.01 and −0.02). The strain measurements by fast cine DENSE and myocardial tagged MRI were strongly correlated (correlation coefficient = 0.92) and in good agreement (mean difference = 0.01; 95% limits of agreement were 0.07 and −0.04). Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
In vivo cytometry of antigen‐specific t cells using 19F MRI
Authors: Srinivas Mangala , Turner Michael S. , Janjic Jelena M. , Morel Penelope A. , Laidlaw David H. , Ahrens Eric T. 
Published: July 2009

AbstractNoninvasive methods to image the trafficking of phenotypically defined immune cells are paramount as we attempt to understand adaptive immunity. A 19F MRI‐based methodology for tracking and quantifying cells of a defined phenotype is presented. These methods were applied to a murine inflammation model using antigen‐specific T cells. The T cells that were intracellularly labeled ex vivo with a perfluoropolyether (PFPE) nanoemulsion and cells were transferred to a host receiving a localized inoculation of antigen. Longitudinal 19F MRI over 21 days revealed a dynamic accumulation and clearance of T cells in the lymph node (LN) draining the antigen. The apparent T‐cell numbers were calculated in the LN from the time‐lapse 19F MRI data. The effect of in vivo T‐cell division on the 19F MRI cell quantification accuracy was investigated using fluorescence assays. Overall, in vivo cytometry using PFPE labeling and 19F MRI is broadly applicable to studies of whole‐body cell biodistribution. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
General formulation for quantitative G‐factor calculation in GRAPPA reconstructions
Authors: Breuer Felix A. , Kannengiesser Stephan A.R. , Blaimer Martin , Seiberlich Nicole , Jakob Peter M. , Griswold Mark A. 
Published: July 2009

AbstractIn this work a theoretical description for practical quantitative estimation of the noise enhancement in generalized autocalibrating partially parallel acquisitions (GRAPPA) reconstructions, equivalent to the geometry (g)‐factor in sensitivity encoding for fast MRI (SENSE) reconstructions, is described. The GRAPPA g‐factor is derived directly from the GRAPPA reconstruction weights. The procedure presented here also allows the calculation of quantitative g‐factor maps for both the uncombined and combined accelerated GRAPPA images. This enables, for example, a fast comparison between the performances of various GRAPPA reconstruction kernels or SENSE reconstructions. The applicability of this approach is validated on phantom studies and demonstrated using in vivo images for 1D and 2D parallel imaging. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Automatic slice positioning (ASP) for passive real‐time tracking of interventional devices using projection‐reconstruction imaging with echo‐dephasing (PRIDE)
Authors: Patil S. , Bieri O. , Jhooti P. , Scheffler K. 
Published: July 2009

AbstractA novel and fast approach for passive real‐time tracking of interventional devices using paramagnetic markers, termed “projection‐reconstruction imaging with echo‐dephasing” (PRIDE) is presented. PRIDE is based on the acquisition of echo‐dephased projections along all three physical axes. Dephasing is preferably set to 4π within each projection ensuring that background tissues do not contribute to signal formation and thus appear heavily suppressed. However, within the close vicinity of the paramagnetic marker, local gradient fields compensate for the intrinsic dephasing to form an echo. Successful localization of the paramagnetic marker with PRIDE is demonstrated in vitro and in vivo in the presence of different types of off‐resonance (air/tissue interfaces, main magnetic field inhomogeneities, etc). In order to utilize the PRIDE sequence for vascular interventional applications, it was interleaved with balanced steady‐state free precession (bSSFP) to provide positional updates to the imaged slice using a dedicated real‐time feedback link. Active slice positioning (ASP) with PRIDE is demonstrated in vitro, requiring approximately 20 ms for the positional update to the imaging sequence, comparable to existing active tracking methods. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Application of nonlinear dimensionality reduction to characterize the conformational landscape of small peptides
Authors: Stamati Hernán , Clementi Cecilia , Kavraki Lydia E. 
Published: July 2009

AbstractThe automatic classification of the wealth of molecular configurations gathered in simulation in the form of a few coordinates that help to explain the main states and transitions of the system is a recurring problem in computational molecular biophysics. We use the recently proposed ScIMAP algorithm to automatically extract motion parameters from simulation data. The procedure uses only molecular shape similarity and topology information inferred directly from the simulated conformations, and is not biased bya prioriknown information. The automatically recovered coordinates prove as excellent reaction coordinates for the molecules studied and can be used to identify stable states and transitions, and as a basis to build free‐energy surfaces. The coordinates provide a better description of the free energy landscape when compared with coordinates computed using principal components analysis, the most popular linear dimensionality reduction technique. The method is first validated on the analysis of the dynamics of an all‐atom model of alanine dipeptide, where it successfully recover all previously known metastable states. When applied to characterize the simulated folding of a coarse‐grained model of β‐hairpin, in addition to the folded and unfolded states, two symmetric misfolding crossings of the hairpin strands are observed, together with the most likely transitions from one to the other. Proteins 2010. © 2009 Wiley‐Liss, Inc.
Dispersive properties of 4f states in rare‐earth systems
Authors: Laubschat C. , Danzenbächer S. , Vyalikh D. V. , Molodtsov S. L. , Kucherenko Yu. 
Published: July 2009

AbstractAngle‐resolved photoemission spectra of Ce, Yb, and Eu systems reveal dispersions and momentum dependent energy splittings of the 4f emissions that are obviously caused by the interaction of localized 4f states with delocalized valenceband states. The spectra may be described satisfactorily in the light of a simplified approach of the periodic Anderson model by a momentum dependence of the electron hopping matrix elements. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Developing a learning progression for scientific modeling: Making scientific modeling accessible and meaningful for learners
Authors: Schwarz Christina V. , Reiser Brian J. , Davis Elizabeth A. , Kenyon Lisa , Achér Andres , Fortus David , Shwartz Yael , Hug Barbara , Krajcik Joe 
Published: July 2009

AbstractModeling is a core practice in science and a central part of scientific literacy. We present theoretical and empirical motivation for a learning progression for scientific modeling that aims to make the practice accessible and meaningful for learners. We define scientific modeling as including the elements of the practice (constructing, using, evaluating, and revising scientific models) and the metaknowledge that guides and motivates the practice (e.g., understanding the nature and purpose of models). Our learning progression for scientific modeling includes two dimensions that combine metaknowledge and elements of practice—scientific models as tools for predicting and explaining, and models change as understanding improves. We describe levels of progress along these two dimensions of our progression and illustrate them with classroom examples from 5th and 6th graders engaged in modeling. Our illustrations indicate that both groups of learners productively engaged in constructing and revising increasingly accurate models that included powerful explanatory mechanisms, and applied these models to make predictions for closely related phenomena. Furthermore, we show how students engaged in modeling practices move along levels of this progression. In particular, students moved from illustrative to explanatory models, and developed increasingly sophisticated views of the explanatory nature of models, shifting from models as correct or incorrect to models as encompassing explanations for multiple aspects of a target phenomenon. They also developed more nuanced reasons to revise models. Finally, we present challenges for learners in modeling practices—such as understanding how constructing a model can aid their own sensemaking, and seeing model building as a way to generate new knowledge rather than represent what they have already learned. © 2009 Wiley Periodicals, Inc. J Res Sci Teach 46: 632–654, 2009
Getting multi‐dimensional trees into a new shape
Authors: Korn Ralf , Müller Stefanie 
Published: July 2009

AbstractThe use of the numerous variants of binomial trees in option pricing is ubiquitous. They are not only easy to understand and to implement, but also range among the most efficient methods for many pricing problems. However, there are at least two main problems regarding their application: In multi‐asset markets, conventional tree construction methods cannot ensure well‐defined transition probabilities for any desired correlation structure between the assets. Furthermore, binomial tree methods often exhib‐it an irregular convergence behavior of the option prices computed for a decreasing sequence of step sizes (i.e. for a sequence of growing trees). The most prominent example of irregular behavior is the so‐called sawtooth effect. In this article we will present a universal method that can overcome both problems at once. Copyright © 2009 Wilmott Magazine Ltd