bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biomimetic organic–inorganic nanocomposite coatings for titanium implants
Authors: Sikirić Maja Dutour , Gergely Csilla , Elkaim Rene , Wachtel Ellen , Cuisinier Frederic J. G. , Füredi‐Milhofer Helga 
Published: May 2008

AbstractA new class of organic–inorganic nanocomposites, to be used as coatings for surface enhancement of metal implants for bone replacement and repair, has been prepared by a biomimetic three‐step procedure: (1) embedding amorphous calcium phosphate (ACP) particles between organic polyelectrolyte multilayers (PE MLs), (2)in situtransformation of ACP to octacalcium phospate (OCP) and/or poorly crystalline apatite nanocrystals by immersion of the material into a metastable calcifying solution (MCS) and (3) deposition of a final PE ML. The organic polyelectrolytes used were poly‐L‐glutamic acid and poly‐L‐lysine. The nanocomposites obtained by each successive step were characterized by scanning electron microscopy, energy dispersive X‐ray analysis (EDS), and XRD, and their suitability as coatings for metal implants was examined by mechanical andin vitrobiological tests. Coatings obtained by the first deposition step are mechanically unstable and therefore not suitable. During the second step, upon immersion into MCS, ACP particles were transformed into crystalline calcium phosphate, with large platelike OCP crystals as the top layer. After phase transformation, the nanocomposite was strongly attached to the titanium, but the top layer did not promote cell proliferation. However, when the coating was topped with an additional PE ML (step 3), smoother surfaces were obtained, which facilitated cell adhesion and proliferation as shown byin vitrobiological tests using primary human osteoblasts (HO) directly seeded onto the nanocomposites. In fact, cell proliferation on nanocomposites with top PE MLs was far superior than on any of the individual components and was equivalent to proliferation on the golden standard (plastic). © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Fibrin scaffold promotes adenoviral gene transfer and controlled vector delivery
Authors: Breen Ailish , Dockery Peter , O'Brien Timothy , Pandit Abhay 
Published: May 2008

AbstractGene therapy using adenoviral vectors in tissue regeneration is hindered by a short duration of transgene expression. It is hypothesized that a fibrin scaffold will enhance delivery of the adenovirus to a wound site, precluding the need for high repeated doses. It was aimed to analyze whether fibrin could deliver a low single dose of viral vector to a wound site, without compromising transfection efficiency. Fibrin scaffold containing adenovirus encoding β‐galactosidase, fibrin alone, adenovirus alone, and no treatment groups were applied to a rabbit ear ulcer model. β‐Galactosidase transgene expression was measured at 7 and 14 days. Transgene expression was enhanced in the fibrin containing adenovirus group at 7 days. By 14 days, there was low expression and no difference between groups. Stereological methods assessing wound healing aimed to determine whether the adenovirus capsid elicited an unfavorable inflammatory response and whether fibrin's beneficial properties were altered by addition of adenovirus. The fibrin adenovirus group showed a wound‐healing response similar to fibrin alone, showing maximum cellularity and angiogenesis at 7 days. By 14 days, cellularity and angiogenesis subsided, and this effect was not inhibited by the presence of adenovirus. Adenovirus alone did not cause an unfavorable inflammatory response. It is concluded the fibrin aids in the delivery of a low‐dose viral vector, thereby avoiding a chronic inflammatory response, and allowing superior transfection than viral vector alone. This has wide‐ranging implications on the use of viral vectors in tissue engineering. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Synthesis and characterization of thermosensitive and pH‐sensitive poly (N‐isopropylacrylamide‐acrylamide‐vinylpyrrolidone) for use in controlled release of naltrexone
Authors: Salehi R. , Arsalani N. , Davaran S. , Entezami A. A. 
Published: May 2008

AbstractIn this article N‐isopropylacrylamide (NIPAAm)‐acrylamide (AAm)‐vinyl pyrrolidone (VP) terpolymers were prepared using free radical copolymerization method by varying feed ratios of monomers. The composition ratio and structure of polymer were determined by NMR and FTIR. The glass transition temperature was examined by DSC. The thermo‐responsive behaviors of polymeric solutions were investigated by turbidimetry using UV‐Visible spectroscopy. The sol–gel transition of the polymer solutions occurred reversibly within 1 min in response to the temperature. By alternating the monomer feed ratio, the synthesized terpolymers had their own distinctive lower critical solution temperature (LCST). In addition to the thermosensitivity, the terpolymers also showed a response to pH changes. The increase in ionic strength of the buffer solution with addition of salt lowered the LCST of the polymers. The ability to shift the phase transition temperature of the terpolymers provided excellent flexibility in tailoring transitions for specific uses. Swelling experiments were performed on the terpolymer disks in buffer solutions with different pH and ionic strength at varying temperature. We investigated naltrexone release as a model drug in phosphate buffer. Drug loading efficiency was varying from 8.75 to 55%. Gel composition, pH, and ionic concentration affected the drug loading. Finally in vitro drug release studies at 36–37°C indicating 35–70% naltrexone release from terpolymers at the end of 30 days. In addition, these gels sustained naltrexone release for 30 days. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Bond‐based 3D‐chiral linear indices: Theory and QSAR applications to central chirality codification
Authors: Castillo‐Garit Juan A. , Marrero‐Ponce Yovani , Torrens Francisco , García‐Domenech Ramón , Romero‐Zaldivar Vicente 
Published: May 2008

AbstractThe recently introduced non‐stochastic and stochastic bond‐based linear indices are been generalized to codify chemical structure information for chiral drugs, making use of a trigonometric 3D‐chirality correction factor. These improved modified descriptors are applied to several well‐known data sets to validate each one of them. Particularly, Cramer's steroid data set has become a benchmark for the assessment of novel quantitative structure activity relationship methods. This data set has been used by several researchers using 3D‐QSAR approaches such as Comparative Molecular Field Analysis, Molecular Quantum Similarity Measures, Comparative Molecular Moment Analysis, E‐state, Mapping Property Distributions of Molecular Surfaces, and so on. For that reason, it is selected by us for the sake of comparability. In addition, to evaluate the effectiveness of this novel approach in drug design we model the angiotensin‐converting enzyme inhibitory activity of perindoprilate's σ‐stereoisomers combinatorial library, as well as codify information related to a pharmacological property highly dependent on the molecular symmetry of a set of seven pairs of chiral N‐alkylated 3‐(3‐hydroxyphenyl)‐piperidines that bind σ‐receptors. The validation of this method is achieved by comparison with earlier publications applied to the same data sets. The non‐stochastic and stochastic bond‐based 3D‐chiral linear indices appear to provide a very interesting alternative to other more common 3D‐QSAR descriptors. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2008
An optimized initialization algorithm to ensure accuracy in quantum Monte Carlo calculations
Authors: Fisher Daniel R. , Kent David R. , Feldmann Michael T. , Goddard William A. 
Published: May 2008

AbstractQuantum Monte Carlo (QMC) calculations require the generation of random electronic configurations with respect to a desired probability density, usually the square of the magnitude of the wavefunction. In most cases, the Metropolis algorithm is used to generate a sequence of configurations in a Markov chain. This method has an inherent equilibration phase, during which the configurations are not representative of the desired density and must be discarded. If statistics are gathered before the walkers have equilibrated, contamination by nonequilibrated configurations can greatly reduce the accuracy of the results. Because separate Markov chains must be equilibrated for the walkers on each processor, the use of a long equilibration phase has a profoundly detrimental effect on the efficiency of large parallel calculations. The stratified atomic walker initialization (STRAW) shortens the equilibration phase of QMC calculations by generating statistically independent electronic configurations in regions of high probability density. This ensures the accuracy of calculations by avoiding contamination by nonequilibrated configurations. Shortening the length of the equilibration phase also results in significant improvements in the efficiency of parallel calculations, which reduces the total computational run time. For example, using STRAW rather than a standard initialization method in 512 processor calculations reduces the amount of time needed to calculate the energy expectation value of a trial function for a molecule of the energetic material RDX to within 0.01 au by 33%. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2008
Structure and dynamics of phosphate ion in aqueous solution: An ab initio QMCF MD study
Authors: Pribil Andreas B. , Hofer Thomas S. , Randolf Bernhard R. , Rode Bernd M. 
Published: May 2008

AbstractA simulation of phosphate in aqueous solution was carried out employing the new QMCF MD approach which offers the possibility to investigate composite systems with the accuracy of a QMMM method but without the time consuming creation of solute–solvent potential functions. The data of the simulations give a clear picture of the hydration shells of the phosphate anion. The first shell consists of 13 water molecules and each oxygen of the phosphate forms in average three hydrogens bonds to different solvent molecules. Several structural parameters such as radial distribution functions and coordination number distributions allow to fully characterize the embedding of the highly charged phosphate ion in the solvent water. The dynamics of the hydration structure of phosphate are described by mean residence times of the solvent molecules in the first hydration shell and the water exchange rate. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2008
Influence of intrinsic defects on the properties of zinc oxide
Authors: Jug Karl , Tikhomirov Viatcheslav A. 
Published: May 2008

AbstractThe effects of oxygen vacancies and zinc interstitials on the structure and energy of zinc oxide were studied with the semiempirical MO method MSINDO. Cyclic clusters were chosen as model systems. Single and multiple removal of oxygen atoms and zinc interstitials in zinc oxide served to determine the defect formation energy and the band gap. The interaction between two and three oxygen vacancies was investigated. The vacancies cause a decrease of the band gap, which originates from an occupied defect level. This is also found for zinc interstitials under zinc rich conditions. The defect formation energy of such zinc interstitials is found to be lower than that of oxygen vacancies at 0 K but decreases for oxygen vacancies and increases for zinc interstitials with increasing temperature. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2008
Mechanistic studies on the formation of glycosidase‐substrate and glycosidase‐inhibitor covalent intermediates
Authors: Brás Natércia F. , Moura‐Tamames Sara A. , Fernandes Pedro A. , Ramos Maria J. 
Published: May 2008

AbstractGlycoside hydrolases catalyze the breaking of the glycosidic bond. This type of bond fashioned between two monosaccharides is very stable, and the polymers created are involved in multiple cellular processes, being crucial to life. In this article, computational methods were used to study the first step of the mechanism of reaction of retaining glycoside hydrolases in atomic detail. The systems modeled included a simplified reaction center and a small substrate/inhibitor. Using DFT calculations we were able to corroborate and provide molecular‐level detail to the dissociative mechanism proposed in the literature. The role of the hydrogen bridge between the nucleophile and the C2OH group of the ring was also investigated. Therefore, we concluded that this bridge is responsible for lowering the activation barrier by 5.1 kcal mol−1 with functional BB1K/6‐311+G(2d,2p), and the absence of the bridge explains, at least in part, the inhibitory effect of fluoro‐substituted glycosides in the −2 position. The hydrogen bridge could also be involved in favoring the ring distortion verified in the transition state, and the dissociative character of the reaction mechanism. Using the NBO method, point atomic charges were calculated. In the transition state, the positive charge generated in the sugar ring is distributed nearly equally between the anomeric carbon and the ring oxygen, through a partial double bond involving the two atoms. © 2008 Wiley Periodicals, Inc. J Comput Chem 2008
Nutritional endoderm: a way to breach the holoblastic–meroblastic barrier in tetrapods
Authors: Elinson Richard P. 
Published: May 2008

AbstractThe deceptively simple evolutionary transition from complete, holoblastic cleavage of the zygote to incomplete, meroblastic cleavage occurred only once in tetrapods, with the evolution of the amniote egg. By examining the development of a frog with large eggs, we identified a new tissue called the nutritional endoderm, which provides a possible intermediate step to breach the holoblastic–meroblastic barrier. Nutritional endoderm is divided into cells, but the cells disappear and do not contribute to tissues of the frog after the yolk is depleted. The complete loss of this yolk‐rich tissue raises the question as to what feature of early development requires cellularization of this endoderm. J. Exp. Zool. Mol. Dev. Evol. 312B:526–532, 2009. © 2008 Wiley‐Liss, Inc.
Climatology of wind patterns in the northeast of the Iberian Peninsula
Authors: Jiménez Pedro A. , González‐Rouco J. Fidel , Montávez Juan P. , García‐Bustamante Elena , Navarro Jorge 
Published: May 2008

AbstractA classification of daily surface wind fields over the Comunidad Foral de Navarra (CFN) region (northeastern Iberian Peninsula (IP)) into wind pattern (WP) types is performed. Daily wind data measured at 41 meteorological stations are employed to represent the surface wind field. Two methodologies are used to develop the classification, one based on the spatial and the other on the temporal similarity. Both methodologies produce comparable results yielding six robust wind patterns. The detected wind field types are season dependent, thereby revealing an annual cycle evolution. The patterns with northwestern circulations are dominant (60.9%) followed by the southeastern ones (30.5%), showing the strong influence of the orography over surface circulations, since valleys in the region are directed mainly along the NW–SE direction.A sea level pressure (SLP) map pattern classification is also performed to evaluate the connections between the synoptic circulations and the surface flows. Eight pressure patterns (PPs) were identified and related to the surface WPs already formed. The associations found were clear enough to understand the forcing mechanism of the different WPs. The ageostrophic balance and the pressure gradient along the valleys seem to successfully describe the general characteristics of the surface circulations over the study region.The behaviour of some atmospheric parameters such as temperature, relative humidity, global radiation and precipitation, which help to describe the atmospheric state associated with each surface circulation type, is also described. They show different advective regimes, and in particular the cold and dry northwestern strong wind locally known as Cierzo and the warm and moist southeastern wind known as Bochorno are recognized. A WP responsible for precipitation episodes of high intensity in the northern region of the CFN is also recognized. Copyright © 2008 Royal Meteorological Society
Pyrazole formation: Examination of kinetics, substituent effects, and mechanistic pathways
Authors: Sloop Joseph C. , Lechner Brent , Washington Gary , Bumgardner Carl L. , Loehle W. David , Creasy William 
Published: May 2008

AbstractReaction kinetics for the condensation of 1,3‐diketones 1a–o with selected arylhydrazines (aryl = Ph, 4‐NO2Ph, 4‐CH3OPh, and 2,4‐diNO2Ph) was studied using 19F NMR spectroscopy. Product regioselectivity is modulated by reactant ratios, substituents, and acidity. Reaction rates were found to be influenced by substituents on the diketones and on phenylhydrazines as well as by acidity of the reaction medium with rates varying as much as 1000‐fold. Hammett ρ values for these cyclizations were determined. The reaction was found to be first order in both the diketone and arylhydrazine. The rate‐determining step for pyrazole formation shifts as a function of pH. Mechanistic details and reaction pathways supporting these findings are proposed. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 370–383, 2008
Consumers' product‐locating behavior: Exploring the application of signal detection theory
Authors: Liu Sandra S. , Chen Jie , Melara Robert D. , Massara Francesco 
Published: May 2008

AbstractThis study explores the application of signal detection theory to the analysis of consumers' product‐locating behavior. Two research questions are addressed: (1) whether characteristics of the shopping environment, including external memory aids and store layout, affect signal‐detection statistics and (2) whether the signal‐detection statistics can be predicted from subjective measures of shopping motivation and product familiarity. The experiments are conducted in a virtual store. The results show that (1) the signal‐detection statistics of sensitivity and response bias can be used to measure product‐locating behavior; (2) external memory aids significantly affect sensitivity; and (3) signal‐detection statistics are significantly associated with shopping motivation. © 2008 Wiley Periodicals, Inc.
Residues of deoxynivalenol (DON) in pig tissue after feeding mash or pellet diets containing low concentrations
Authors: Döll Susanne , Dänicke Sven , Valenta Hana 
Published: May 2008

AbstractResidues of deoxynivalenol (DON) and its metabolite de‐epoxy‐DON (DOM) were analyzed in specimens of pigs fed diets containing 0, 25, and 50% contaminated wheat (2.5 mg DON/kg) fed as mash or pellets over the final growing period of 11 wk. Median DON concentrations decreased from bile > kidney > serum > liver = muscle, while DOM was only detected in bile and kidney. Maximum carry over rates were 0.0319 for kidney, 0.0064 for liver, and 0.0043 for muscle, demonstrating that the contribution of animal derived food to the consumers' exposure is very low. The high interindividual variation of DON concentrations in all analyzed specimen of pigs fed diets containing similar concentrations of DON does not allow a diagnostic differentiation of animals fed diets containing DON concentrations of approximately 61% of the guidance level of 0.9 mg DON/kg, and those fed diets containing 137% of this concentration. The different feed forms did not affect residue concentrations in any of the investigated specimens.
Modulation of cytokine production by plant sterols in stimulated human Jurkat T cells
Authors: Aherne S. Aisling , O'Brien Nora M. 
Published: May 2008

AbstractThe plant sterols campesterol, β‐sitosterol and β‐sitostanol were investigated for potential immunomodulatory effects in Jurkat T cells. Treatments involved supplementing cells with or without concanavalin A (ConA) or phorbol‐12‐myristate‐13‐acetate plus ionomycin (PMA+IoM) in the presence or absence of increasing concentrations (10–100 μM) of each plant sterol for 24 h. None of the plant sterols significantly affected mitogen‐stimulated IL‐4, IL‐10 or IFN‐γ production. However, campesterol, β‐sitosterol and β‐sitostanol significantly suppressed mitogen‐induced IL‐2 production in a dose‐dependent manner. Both bisindolylmaleimide‐I (BIM‐I), a specific protein kinase C (PKC) inhibitor, and the immunosuppressant drug known as Tacrolimus (FK506), an IL‐2 inhibitor, prevented mitogen‐stimulated IL‐2 production in Jurkat cells. Treatment with PMA+IoM alone significantly increased PKC activity and the presence of BIM‐I prevented PKC activation by PMA+IoM. Following 24 h treatments, the plant sterols did not affect PMA+IoM‐enhanced PKC activity, cellular calcium content or calcineurin activity. Intracellular cyclic 3′,5′‐adenosine monophosphate (cAMP) levels were significantly reduced by PMA+IoM. The presence of FK506 prevented a PMA+IoM‐induced reduction of intracellular cAMP. Likewise the plant sterols behaved in a similar manner as FK506. Our findings suggest that the suppression of IL‐2 by the plant sterols was not mediated via PKC inhibition and that their effects occurred possibly via cAMP modulation and/or a calcium/calcineurin‐independent pathway.
Quantitative prediction of ischemic stroke tissue fate
Authors: Shen Qiang , Duong Timothy Q. 
Published: May 2008

AbstractAccurate prediction of ischemic tissue fate could aid clinical decision‐making in the treatment of acute stroke. We investigated predictions of tissue fate for three (30‐min, 60‐min and permanent) stroke models in rats. Quantitative cerebral blood flow (CBF), apparent diffusion coefficient (ADC) and spin–spin relaxation time constant (T2) were acquired during the acute phase and at the end point followed by histological examination. Probability‐of‐infarct profiles based on ADC and CBF data were constructed using a training dataset. Probability‐of‐infarct maps were predicted using only acute stroke data from a separate experimental dataset, revealing the likelihood of future infarction. Performance measures of sensitivity and specificity showed accurate predictions. Sensitivities (mean ± SD) for the 30‐min, 60‐min and permanent stroke were, respectively, 82 ± 6%, 82 ± 7%, and 86 ± 4%, specificities were 83 ± 5%, 86 ± 5%, and 89 ± 6%, and the areas under the receiver operating curve were 87 ± 3%, 90 ± 4%, and 93 ± 3%. Importantly, to improve prediction accuracy, we took into account regional susceptibility to infarction. Spatial frequency‐of‐infarct maps were constructed and predictions were made by taking the weighted average of the probability‐of‐infarct map and spatial frequency‐of‐infarct map. The optimal weighting coefficient of spatial frequency‐of‐infarct was small (10%) for the permanent occlusion group but surprisingly large (40%) for the reperfusion groups, indicating that regional susceptibility of infarction was important for accurate prediction in reperfusion stroke. We concluded that the likelihood of cerebral infarction in rats can be accurately predicted and that accounting for regional susceptibility of infarct further improves prediction accuracy. Predictive models have the potential to provide a valuable quantitative framework for clinicians to consider different stroke treatment options. Copyright © 2008 John Wiley & Sons, Ltd.