bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis, Optical Resolution and Enantiomeric Recognition Ability of Novel, Inherently Chiral Calix[4]arenes: Trial Application to Asymmetric Reactions as Organocatalysts
Authors: Shirakawa Seiji , Moriyama Akihiro , Shimizu Shoichi
Published: November 2008

Newly designed, inherently chiral calix[4]arenes containing amino phenol structures have been synthesized and resolved to optically pure forms. The enantiomeric recognition ability of one chiral calix[4]arene was examined with mandelic acid by 1H NMR spectroscopy, and we found that the inherently chiral calix[4]arene could be used as a chiral NMR solvating agent to determine the enantiopurity of mandelic acid at ambient temperature. In addition, the chiral calix[4]arenes were used as organocatalysts in asymmetric Michael‐type addition reactions of thiophenols, and high catalytic efficiency with low enantioselectivity was observed.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Kinetic Resolution of Racemic Carboxylic Acids Using Achiral Alcohols by the Promotion of Benzoic Anhydrides and Tetramisole Derivatives: Production of Chiral Nonsteroidal Anti‐Inflammatory Drugs and Their Esters
Authors: Shiina Isamu , Nakata Kenya , Onda Yu‐suke
Published: November 2008

A variety of optically active carboxylic esters were produced by kinetic resolution of racemic carboxylic acids by using achiral alcohols, benzoic anhydrides, and Birman's tetramisole‐type catalysts. Bis(α‐naphthyl)methanol is a very effective reagent for producing the corresponding esters with high ee values in the presence of 4‐methoxybenzoic anhydride (PMBA) as the coupling reagent by promotion of benzotetramisole derivatives (BTM, α‐Np‐BTM, and β‐Np‐BTM). This protocol directly provides chiral carboxylic esters from free carboxylic acids and achiral alcohols by utilizing a transacylation process to generate the mixed anhydrides from the acid components with benzoic anhydride derivatives in the presence of chiral catalysts.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Protein extraction and 2‐DE of water‐ and lipid‐soluble proteins from bovine pericardium, a low‐cellularity tissue
Authors: Griffiths Leigh G. , Choe Leila , Lee Kelvin H. , Reardon Kenneth F. , Orton E. Christopher
Published: November 2008

Bovine pericardium (BP) is an important biomaterial used in the production of glutaraldehyde‐fixed heart valves and tissue‐engineering applications. The ability to perform proteomic analysis on BP is useful for a range of studies, including investigation of immune rejection after implantation. However, proteomic analysis of fibrous tissues such as BP is challenging due to their relative low‐cellularity and abundance of extracellular matrix. A variety of methods for tissue treatment, protein extraction, and ;fractionation were investigated with the aim of producing high‐quality 2‐DE gels for both water‐ and lipid‐soluble BP proteins. Extraction of water‐soluble proteins with 3‐(benzyldimethylammonio)‐propanesulfonate followed by n‐dodecyl β‐D‐maltoside extraction and ethanol precipitation for lipid‐soluble proteins provided the best combination of yield, spot number, and resolution on 2‐DE gels (Protocol E2). ESI‐quadrupole/ion trap or MALDI‐TOF/TOF MS protein identifications were performed to confirm bovine origin and appropriate subcellular prefractionation of resolved proteins. Twenty‐five unique, predominantly cytoplasmic bovine proteins were identified from the water‐soluble fraction. Thirty‐two unique, predominantly membrane bovine proteins were identified from the lipid‐soluble fraction. These results demonstrated that the final protocol produced high‐quality proteomic data from this important tissue for both cytoplasmic and membrane proteins.
Heat Effects of Dehydration of Human Serum Albumin in Hydrophilic Organic Solvents
Authors: Sirotkin V. A. , Sukhov A. V. , Dudkina E. V.
Published: November 2008

A thermochemical model for describing the transfer of water from the protein phase to the organic solvent liquid phase and for determining how the solvation ability of organic solvents affects this process was developed. Enthalpy changes on the interaction of dried and hydrated human serum albumin (HSA) with hydrophilic organic solvents (dimethyl sulfoxide, formamide, ethanol, methanol and acetic acid) and water were measured by isothermal calorimetry at 25 °C. The initial hydration level of human serum albumin was varied in the entire water content range from 0–30 % [g water/g HSA]. The dependence of the interaction enthalpies on the initial water content is complex. The interaction enthalpies of the dried HSA with organic solvents are exothermic. At low water contents (less than 0.1 g/g), there is a sharp increase in the interaction enthalpy values. At the highest water contents (more than 0.2 g/g), the interaction enthalpies are endothermic for acetic acid and formamide and exothermic for DMSO, methanol, and ethanol. These thermochemical data were analyzed in conjunction with the results for the water adsorption in organic solvents to calculate the molar enthalpies of dehydration of HSA in organic liquids. It was found that the dehydration enthalpy changes may be endothermic or exothermic depending on the initial water content and the water solvation enthalpy value. From the results obtained, it can be concluded that: (i) only the solvation of water by hydrophilic organic solvent determines the changes in the dehydration enthalpy values, and (ii) the data for the enthalpies of solvation of water by the solvent at infinite dilution reflect this effect.
Accurate magnetic field evaluation due to underground power cables
Authors: Machado V. Maló , Almeida M. E. , Neves M. Guerreiro das
Published: November 2008

Exposure to low frequency magnetic fields has been a matter of health concern and controversy over the past years. These aspects motivated the development of methods and algorithms for the magnetic field evaluation due to power transmission lines and cables. In this paper special attention is given to buried power transmission cables. Results for different values of frequency and different values for the magnetic permeability of the soil are obtained, presented and compared with a standard approximation. Results confirm the importance of the method developed in this paper, not only as a reference method but also as a mandatory method for higher values of the soil magnetic permeability and higher values of the frequency. Copyright © 2008 John Wiley & Sons, Ltd.
Estimation of the critical clearing time using MLP and RBF neural networks
Authors: Karami Ali
Published: November 2008

This paper presents multi‐layer perceptron (MLP) and radial basis function (RBF) neural networks (NNs) based methods for the estimation of the critical clearing time (tcr) as an index for power systems transient stability analysis (TSA). The tcr evaluation involves elaborate computations that often include time‐consuming solutions of nonlinear on‐fault and post‐fault systems equations. Knowing that for a particular fault scenario (contingency), the tcr is a function of the pre‐fault system operating point, the objective of this paper is to show how one may develop the MLP and the RBF NNs based methods for estimating the tcr by using only the pre‐fault operating conditions as the inputs of the NNs. The paper uses the proposed MLP and RBF NNs based methods to estimate the tcr under different topological as well as operating conditions of the 10‐machane 39‐bus New England test power system, and results are given. The simulation results show that both NNs are able to retain past learned information almost instantaneously. However, compared to the RBF NN, the MLP NN makes us have a more accurate estimation for the tcr. Copyright © 2008 John Wiley & Sons, Ltd.
Some improvements on free surface simulation by the particle finite element method
Authors: Tang B. , Li J. F. , Wang T. S.
Published: November 2008

The Lagrangian method has become increasingly popular in numerical simulation of free surface problems. In this paper, after a brief review of a recent Lagrangian method, namely the particle finite element method, some issues are discussed and some improvements are made. The least‐square finite element method is adopted to simplify the solving of the Navier–Stokes equations. An adaptive time method is derived to obtain suitable time steps. A mass correction procedure is imported to improve the mass conservation in long time calculations and time discretization scheme is adopted to decrease the pressure oscillations during the calculations.

Finally, the method is used to simulate a series of examples and the results are compared with the commercial FLOW3D code. Copyright © 2008 John Wiley & Sons, Ltd.
Implicit meanflow–multigrid algorithms for Reynolds stress model computation of 3‐D anisotropy‐driven and compressible flows
Authors: Gerolymos G. A. , Vallet I.
Published: November 2008

The present paper investigates the multigrid (MG) acceleration of compressible Reynolds‐averaged Navier–Stokes computations using Reynolds‐stress model 7‐equation turbulence closures, as well as lower‐level 2‐equation models. The basic single‐grid SG algorithm combines upwind‐biased discretization with a subiterative local‐dual‐time‐stepping time‐integration procedure. MG acceleration, using characteristic MG restriction and prolongation operators, is applied on meanflow variables only (MF–MG), turbulence variables being simply injected onto coarser grids. A previously developed non‐time‐consistent (for steady flows) full‐approximation‐multigrid (s–MG) is assessed for 3‐D anisotropy‐driven and/or separated flows, which are dominated by the convergence of turbulence variables. Even for these difficult test cases CPU‐speed‐ups rCPUSUP∈[3, 5] are obtained. Alternative, potentially time‐consistent approaches (unsteady u–MG), where MG acceleration is applied at each subiteration, are also examined, using different subiterative strategies, MG cycles, and turbulence models. For 2‐D shock wave/turbulent boundary layer interaction, the fastest s–MG approach, with a V(2, 0) sawtooth cycle, systematically yields CPU‐speed‐ups of 5±½, quasi‐independent of the particular turbulence closure used. Copyright © 2008 John Wiley & Sons, Ltd.
Simulation of a turbulent channel flow with an entropic Lattice Boltzmann method
Authors: Spasov M. , Rempfer D. , Mokhasi P.
Published: November 2008

The Lattice Boltzmann method (LBM) is used to simulate turbulent channel flow. Two simulations are performed. One uses high enough grid resolution in order for it to be considered a direct numerical simulation (DNS). LBM in its traditional form is adopted for this simulation. The other simulation uses lower resolution for which the original method becomes unstable. An entropy condition is used to render this simulation stable. Results from these two numerical experiments are compared with the results from a DNS performed with traditional numerical techniques. It is concluded that LBM can be used as tool to simulate turbulent flows and entropy stabilized LBM schemes can be used to achieve accurate results with reasonably low grid resolution. Copyright © 2008 John Wiley & Sons, Ltd.
Flow analysis for a double suction centrifugal machine in the pump and turbine operation modes
Authors: González José , Fernández Oro Jesús Manuel , Argüelles‐Díaz Katia M. , Santolaria Carlos
Published: November 2008

A double suction centrifugal machine has been studied, both experimentally and numerically, operating as a pump and as a turbine. Experimentally, the static performance of the machine working as a pump was obtained. These measurements were compared with equivalent numerical results from a URANS calculation. As a second step, the numerical results have been exploited to get detailed information about the flow in both operating modes (pump and turbine).

The main goals of the study are, first, the validation of the numerical procedure proposed and second, the possible turbine operation of the impeller, which could point out a wider working range for the machine. The first aspect is handled by detailed analysis in the pump mode, according to previous experience of the research group. The second objective is obtained by using the numerical model to explore the flow fields obtained, when working in an inverse mode. Therefore, the presented results join the use of a numerical methodology and the turbine mode of operation for a centrifugal impeller, providing insight into the flow characteristics.

When working as a pump, the flow at the suction side is characterized by the existence of an inlet tongue, which tends to enforce a uniform flow for the nominal conditions. For the turbine mode, flow patterns in the impeller, volute and suction regions are carefully investigated. The influence of the specific geometrical arrangement is also considered for this operation mode. Copyright © 2008 John Wiley & Sons, Ltd.
Treatment with galantamine and time to nursing home placement in Alzheimer's disease patients with and without cerebrovascular disease
Authors: Feldman Howard H. , Pirttila Tuula , Dartigues Jean François , Everitt Brian , Van Baelen Bart , Schwalen Susanne , Kavanagh Shane
Published: November 2008

Objective

This study evaluated patient and treatment (galantamine and other acetylcholinesterase inhibitors (AChEIs)) factors associated with the time until nursing home placement (NHP) in patients with Alzheimer's disease (AD) with and without cerebrovascular disease (CVD).

Methods

Re‐contact follow‐up study conducted in 2004 of 548 patients who had previously participated in RCTs with galantamine. Time to NHP was analyzed using Kaplan‐Meier estimates and Cox regression analysed factors associated with NHP.

Results

There were 57% of female subjects and the mean age (SE) was 73.6 (±0.33) years. Within this cohort 78% of patients had AD, and 22% had AD with CVD. Overall, 59% of subjects had a NHP (median 42.4 months 95%CI: 38.0–48.0). The Cox regression model identified higher baseline Disability Assessment in Dementia (DAD) and Mini Mental State Examination (MMSE) scores, diagnosis (AD with CVD vs AD), living with caregiver, country, and treatment duration with galantamine or other AChEIs as factors associated with a reduced risk of institutionalization (p < 0.05). For each year of treatment with galantamine or other AChEI, the risk of being admitted to a nursing home within a given period was reduced by 31% (galantamine) and 29% (other AChEI).

Conclusions

Long‐term treatment with galantamine or other AChEIs appears to be associated with a significant delay in the time to NHP in patients with AD and AD with CVD. Further prospective studies are needed to confirm these findings. Copyright © 2008 John Wiley & Sons, Ltd.
Next‐day residual effects of gaboxadol and flurazepam administered at bedtime: a randomized double‐blind study in healthy elderly subjects
Authors: Boyle Julia , Wolford Dennis , Gargano Cynthia , McCrea Jacqueline , Cummings Corinne , Cerchio Kristine , Lines Christopher
Published: November 2008

Objective

To evaluate the next‐day residual effects of the novel hypnotic, gaboxadol, following bedtime dosing in healthy elderly subjects.

Methods

Healthy women (N = 15) and men (N = 10) aged 65–79 years received a single bedtime (22:00 h) dose of gaboxadol 10 mg, flurazepam 30 mg (positive control), and placebo in a randomized, double‐blind, crossover study. Measures of information processing and psychomotor performance (choice reaction time, critical flicker fusion, digit symbol substitution, compensatory tracking, body sway), memory (immediate and delayed word recall), and daytime sleepiness (Multiple Sleep Latency Test), as well as subjective ratings (line analog rating scales, Leeds Sleep Evaluation Questionnaire), were obtained starting at 07:00 h the following morning. Adverse events were recorded.

Results

Gaboxadol did not show next‐day impairments versus placebo on any pharmacodynamic measures whereas the positive control, flurazepam, did show impairments versus placebo on most measures. Gaboxadol showed improvements versus placebo on some measures including subjective rating of next‐day alertness/clumsiness on the Leeds Sleep Evaluation Questionnaire. Gaboxadol was generally well‐tolerated; there were no serious adverse experiences and no subjects discontinued due to an adverse experience.

Conclusions

A single oral bedtime dose of gaboxadol 10 mg did not have next‐day residual effects in healthy elderly subjects, as measured by a range of pharmacodynamic assessments, in contrast to the clear impairments produced by flurazepam 30 mg. Copyright © 2008 John Wiley & Sons, Ltd.
Immunological responses in C3H/HeJ mice following nose‐only inhalation exposure to different sizes of beryllium metal particles
Authors: Salehi Fariba , Zayed Joseph , Audusseau Séverine , Muller Caroline , Truchon Ginette , Plamondon Philippe , L'Espérance Gilles , Chevalier Gaston , Mazer Bruce
Published: November 2008

Beryllium is used in a wide variety of industries. Chronic beryllium disease is the most common occupational disease among workers following exposure to Be. The objective of this study was to determine the immunologic effects of two different particle sizes of Be metal, <2.5 µm (fine Be or Be‐F) and <10 µm (inhalable Be or Be‐I) on C3H/HeJ mice following 3 weeks of nose‐only inhalation exposure at a target concentration of 250 µg m−3. Mice were sacrificed either on day 28 or day 42 (Be‐F group only) after exposure. The mass median aerodynamic diameter obtained in the inhalation chamber was 1.5 ± 0.1 µm for Be‐F and 4.1 ± 0.6 µm for Be‐I. Results showed peri‐bronchial inflammation with early granulomatous changes in exposed mice. The extent of the inflammation appeared more severe for mice sacrificed at day 42. Splenocyte proliferation was higher for mice exposed to fine particles compared with Be‐I and control animals. Flow‐cytometric analysis indicated a significantly greater expression of CD4+, CD8+ and intracellular IFN‐γ expression for both Be particle sizes, particularly for fine particles. Cytokine assays of bronchoalveolar lavage revealed significantly greater levels of IL‐12, TNF‐α and IFN‐γ for mice exposed to fine particles. Our findings suggest that exposure to fine particles may induce more pronounced immunological effects than inhalable particles. Copyright © 2008 John Wiley & Sons, Ltd.
Metabolic significance of bisphenol A‐induced oxidative stress in rat urine measured by liquid chromatography–mass spectrometry
Authors: Cho Sung‐Hee , Choi Man Ho , Kwon Oh Seung , Lee Won‐Yong , Chung Bong Chul
Published: November 2008

Modified nucleosides are formed by DNA repair as a result of oxidative DNA damage and post‐transcriptionally modified tRNA in cells. In the present study, profiling of 14 nucleoside was investigated in rat urine to evaluate bisphenol A (BPA)‐induced oxidative stress after intraperitoneally injecting rats with 0, 10 or 50 mg kg−1 per day of BPA for four consecutive days. The urinary concentrations of individual nucleosides were measured by liquid chromatography–tandem mass spectrometry combined with column switching on‐line extraction. Increased levels of 5‐hydroxymethyl‐2′‐deoxyuridine (P <0.01 on first, P <0.005 on second, P <0.001 on third and P <0.01 on fourth day) and 8‐hydroxy‐2′‐deoxyguanosine (P <0.005 on second, P <0.001 on third and P <0.001 on fourth day) were found. Also, the patterns of urinary nucleosides in three dosage groups (control, BPA1, BPA2) were significantly different. Statistical significance was observed between BPA1 (5‐hydroxymethyl‐2′‐deoxyuridine, P <0.05; 8‐hydroxy‐2′‐deoxyguanosine, P <0.005) and BPA2 (5‐hydroxymethyl‐2′‐deoxyurindine, P <0.005; 8‐hydroxy‐2′‐deoxyguanosine, P <0.001) during the treatment period. Supervised analysis with partial least‐squares‐discrimination analysis led to discrimination between the three dosage groups. Quantitative alterations showed the metabolic trajectories responsible for physiological responses. The described methods could be used to evaluate and monitor BPA‐induced oxidative stress early after exposure. Copyright © 2008 John Wiley & Sons, Ltd.
Bioinspired superhydrophobic poly(L‐lactic acid) surfaces control bone marrow derived cells adhesion and proliferation
Authors: Alves Natália M. , Shi Jun , Oramas Elena , Santos José L. , Tomás Helena , Mano João F.
Published: November 2008

The aptitude of a cell to adhere, migrate, and differentiate on a compact substrate or scaffold is important in the field of tissue engineering and biomaterials. It is well known that cell behavior can be controlled and guided through the change in micro‐ and nano‐scale topographic features. In this work, we intend to demonstrate that special topographic features that control wettability may also have an important role in the biological performance of biodegradable substrates. Poly(L‐lactic acid) surfaces with superhydrophobic characteristics were produced, based on the so‐called Lotus effect, exhibiting dual micro‐ and nano‐scale roughness. The water contact angle could be higher than 150° and a value of that order could be kept even upon immersion in a simulated body fluid solution for more than 20 days. Such water repellent surfaces were found to prevent adhesion and proliferation of bone marrow derived cells previously isolated from the femurs of 6‐week‐old male Wistar rats, when compared with smoother surfaces prepared by simple solvent casting. Such results demonstrate that these superhydrophobic surfaces may be used to control cell behavior onto biodegradable substrates. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Methods to promote Notch signaling at the biomaterial interface and evaluation in a rafted organ culture model
Authors: Beckstead Benjamin L. , Tung Jason C. , Liang Katharine J. , Tavakkol Zarry , Usui Marcia L. , Olerud John E. , Giachelli Cecilia M.
Published: November 2008

The Notch signaling pathway is a promising target for controlling cell fate choices at the biomaterial‐tissue interface. Building on our previous work in developing Notch‐signaling biomaterials, we evaluated various immobilization schemes for Notch ligands, and their effect on human foreskin keratinocytes. A peptide sequence derived from the Jagged‐1 DSL‐region and immobilized to poly(2‐hydroxyethyl methacrylate) (polyHEMA) showed no bioactivity in relation to the Notch‐CSL pathway. The full‐length Jagged‐1 protein immobilized directly to the polyHEMA surface showed activity in signaling the Notch‐CSL pathway. However, an indirect affinity immobilization approach yielded a stronger signal. Human keratinocytes plated on bound Jagged‐1 showed upregulated involucrin, keratin 10, and loricrin protein expression, with this expression being cell density‐dependent. Utilizing a human foreskin rafted organ culture model as a bridge between in vitro and in vivo studies, Jagged‐1‐modified or control polyHEMA rods were implanted in human foreskin and cultured at the air‐medium interface. Keratinocyte proliferation was suppressed and intermediate‐stage differentiation promoted in Jagged‐1‐modified rods compared with control rods. Thus, Notch‐signaling biomaterials provide a robust approach to control keratinocyte differentiation and may find application to other progenitor and stem cells. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res 2009
Preparation and characterization of alginate/gelatin blend films for cardiac tissue engineering
Authors: Rosellini Elisabetta , Cristallini Caterina , Barbani Niccoletta , Vozzi Giovanni , Giusti Paolo
Published: November 2008

The aim of this work was the preparation of blends based on alginate and gelatin, with different weight ratio, to combine the advantages of these two natural polymers for application in cardiac tissue engineering. The physicochemical characterization, performed by Fourier transform infrared spectroscopy, differential scanning calorimetry and thermogravimetric analysis, revealed a good miscibility and the presence of interactions among the functional groups of pure biopolymers. Concerning the swelling and degradation tests, performed in different solutions simulating body fluids, both swelling degree and weight losses were higher in phosphate buffer saline (PBS) and for the blends with a higher content of gelatin. These results indicated a better stability of the blends in cell culture medium than in PBS and suggested a mainly hydrolytic degradation process. Cell culture tests, carried out using C2C12 myoblasts, showed a good cell proliferation for all the blends containing more than 60% of gelatin, with the alginate/gelatin 20:80 showing the best response. The same blend was the only one on which cell differentiation was observed. The results obtained in the biological characterization allow to select the alginate/gelatin 20:80 blend as a suitable material to prepare scaffolds for myocardial tissue engineering. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Addition of TPGS to folate‐conjugated polymer micelles for selective tumor targeting
Authors: Zhao Haizheng , Yung Lin Yue Lanry
Published: November 2008

Folate‐conjugated polymer micelles poly(D,L‐lactide‐co‐glycolide)‐poly(ethylene glycol)‐folate (PLGA‐PEG‐FOL) was fabricated to encapsulate anticancer drug doxorubicin for targeting delivery to cancer cells with overexpression of folate receptors. To increase therapeutic effect, D‐α‐tocopheryl polyethylene glycol succinate (TPGS) was added during the micelles preparation. The physicochemical study showed that the mixed micelles of PLGA‐PEG‐FOL and TPGS formed a homogeneous population. The addition of TPGS did not result in much variation in the micellar size, surface charge, and drug encapsulation efficiency. The cellular uptake study showed that mixed micelles with TPGS had higher cellular uptake compared with the ones without TPGS to drug‐resistant cancer cells. These mixed micelles also selectively increased the cytotoxicity of drug on cancer cells but exhibited minimal cytotoxic enhancement on normal fibroblasts. Furthermore, the accumulation of rhodamine study showed that the mixed micelles with TPGS increased the cellular uptake of drugs on Caco‐2 cells. This indicates that TPGS in the mixed micelles may act as P‐glycoprotein inhibitor to reduce drug efflux. This new formulation with TPGS may have dual functions of folate‐mediated targeting and multidrug resistance inhibition and can be promising in improving the therapeutic efficacy of polymer micellar targeting delivery system. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Melt‐based compression‐molded scaffolds from chitosan–polyester blends and composites: Morphology and mechanical properties
Authors: Correlo V. M. , Boesel L. F. , Pinho E. , Costa‐Pinto A. R. , Alves da Silva M. L. , Bhattacharya M. , Mano J. F. , Neves N. M. , Reis R. L.
Published: November 2008

Blends of chitosan and synthetic aliphatic polyesters (polybutylene succinate, polybutylene succinate adipate, polycaprolactone, and polybutylene terepthalate adipate) were compounded with and without hydroxyapatite, a bioactive mineral filler known to enhance osteoconduction. The blends and composites were compression molded with two different granulometric salt sizes (63–125 μm and 250–500 μm) having different levels of salt content (60, 70, and 80%) by weight. By leaching the salt particles, it was possible to produce porous scaffolds with distinct morphologies. The relationship between scaffold morphology and mechanical properties was evaluated using scanning electron microscopy, microcomputed tomography, compression testing, differential scanning calorimetry, small‐angle X‐ray scattering (SAXS), and wide‐angle X‐ray scattering. The produced scaffolds are characterized by having different morphologies depending on the average particle size and the amount of NaCl used. Specimens with higher porosity level have a less organized pore structure but increased interconnectivity of the pores. The stress–strain curve under compression displayed a linear elasticity followed by a plateau whose characteristics depend on the scaffold polymer composition. A decrease in the salt particle size used to create the porosity caused in general a decrease in the mechanical properties of the foams. Composites with hydroxyapatite had a sharp reduction in yield stress, modulus, and strain at break. The melting temperature decreased with increased chitosan content. SAXS results indicate no preferential crystalline orientation in the scaffolds. Cytotoxicity evaluation were carried out using standard tests (accordingly to ISO/EN 10993 part 5 guidelines), namely MTS test with a 24‐h extraction period, revealing that L929 cells had comparable metabolic activities to that obtained for the negative control. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Assessment of novel chemical strategies for covalent attachment of adhesive peptides to rough titanium surfaces: XPS analysis and biological evaluation
Authors: Dettin Monica , Herath Thushari , Gambaretto Roberta , Iucci Giovanna , Battocchio Chiara , Bagno Andrea , Ghezzo Francesca , Di Bello Carlo , Polzonetti Giovanni , Di Silvio Lucy
Published: November 2008

Bioactive molecules have been proposed to promote beneficial interactions at bone‐implant interfaces for enhancing integration. The main objective of this study was to develop novel methods to functionalize oxidized titanium surfaces by the covalent immobilization of bioactive peptides, through selective reaction involving single functional groups. In the first protocol, an aminoalkylsilane was covalently linked to the Ti oxide layer, followed by covalent binding of glutaric anhydride to the free NH2 groups. The carboxylic group of glutaric anhydride was used to condense the free N‐terminal group of the side‐chain protected peptide sequence. Finally, the surface was treated with trifluoroacetic acid to deprotect side‐chain groups. In the second protocol, the peptide was directly anchored to the Ti oxide surface via UV activation of an arylazide peptide analogue. X‐ray photoelectron spectroscopy analyses confirmed that modifications induced onto surface composition were in agreement with the reactions performed. The peptide density of each biomimetic surface was determined on the basis of radiolabeling and XPS derived reaction yields. The in vitro cellular response of the biomimetic surfaces was evaluated using a primary human osteoblast cell model. Cell adhesion, proliferation, differentiation, and mineralization were examined at initial‐, short‐, and long‐time periods. In was shown that the biomimetic surface obtained through photoprobe‐marked analogue that combines an easily‐performed modification provides a favorable surface for an enhanced cellular response. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Distinct extracellular matrix microenvironments of progenitor and carotid endothelial cells
Authors: Vartanian Keri B. , Kirkpatrick Sean J. , McCarty Owen J. T. , Vu Tania Q. , Hanson Stephen R. , Hinds Monica T.
Published: November 2008

Endothelial cells (ECs) produce and maintain the local extracellular matrix (ECM), a critical function that contributes to EC and blood vessel health. This function is also crucial to vascular tissue engineering, where endothelialization of vascular constructs require a cell source that readily produces and maintains ECM. In this study, baboon endothelial progenitor cell (EPC) deposition of ECM (laminin, collagen IV, and fibronectin) was characterized and compared to mature carotid ECs, evaluated in both elongated and cobblestone morphologies typically found in vivo. Microfluidic micropatterning was used to create 15‐μm wide adhesive lanes with 45‐μm spacing to reproduce the elongated EC morphology without the influence of external forces. Both EPCs and ECs elongated on micropatterned lanes had aligned actin cytoskeleton and readily deposited ECM. EPCs deposited and remodeled the ECM to a greater extent than ECs. Since a readily produced ECM can improve graft patency, EPCs are an advantageous cell source for endothelializing vascular constructs. Furthermore, EC deposition of ECM was dependent on cell morphology, where elongated ECs deposited more collagen IV and less fibronectin compared to matched cobblestone controls. Thus micropatterned surfaces controlled EC shape and ECM deposition, which ultimately has implications for the design of tissue‐engineered vascular constructs. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Three‐dimensional conductive constructs for nerve regeneration
Authors: George Paul M. , Saigal Rajiv , Lawlor Michael W. , Moore Michael J. , LaVan David A. , Marini Robert P. , Selig Martin , Makhni Melvin , Burdick Jason A. , Langer Robert , Kohane Daniel S.
Published: November 2008

The unique electrochemical properties of conductive polymers can be utilized to form stand‐alone polymeric tubes and arrays of tubes that are suitable for guides to promote peripheral nerve regeneration. Noncomposite, polypyrrole (PPy) tubes ranging in inner diameter from 25 μm to 1.6 mm as well as multichannel tubes were fabricated by electrodeposition. While oxidation of the pyrrole monomer causes growth of the film, brief subsequent reduction allowed mechanical dissociation from the electrode mold, creating a stand‐alone, conductive PPy tube. Conductive polymer nerve guides made in this manner were placed in transected rat sciatic nerves and shown to support nerve regeneration over an 8‐week time period. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Orthopedic nano diamond coatings: Control of surface properties and their impact on osteoblast adhesion and proliferation
Authors: Yang Lei , Sheldon Brian W. , Webster Thomas J.
Published: November 2008

The superior mechanical and tribological properties of diamond coatings suggest their promise for improving current orthopedic implants. Therefore, understanding and controlling biological responses on diamond coatings are important and necessary for their advancement in orthopedics. For this reason, the objective of the present study was to correlate surface properties of diamond coatings with osteoblast (OB) adhesion and proliferation. Diamond coatings on silicon of variable surface features (specifically, grain size, surface roughness and surface chemistry) were fabricated by microwave plasma enhanced chemical‐vapor‐deposition (MPCVD). Scanning electron microscopy (SEM) as well as atomic force microscopy (AFM) was applied for topographical characterization and contact angles were measured to assess surface wettability. Results revealed that the grain size, surface roughness and wettability of diamond coatings can be controlled by adjusting H2 plasma in the MPCVD process. Further, results showed enhanced OB adhesion on nanocrystalline diamond (ND) with grain sizes less than 100 nm whereas nanostructured diamond/amorphous carbon coatings (NDp) and microcrystalline diamond (MD) inhibited OB adhesion. H2 plasma treated ND (NDH) also promoted OB adhesion. Similarly, OB proliferated to a greater extent on ND and NDH compared with MD and uncoated silicon controls. In summary, surface properties (including topography and chemistry) of diamond coatings can be controlled to either promote or inhibit OB functions, which implies that various forms of diamond coatings can be used to either support or inhibit bone growth in different regions of an orthopedic implant. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Calcium phosphate surface treatment of bioactive glass causes a delay in early osteogenic differentiation of adipose stem cells
Authors: Haimi Suvi , Moimas Loredana , Pirhonen Eija , Lindroos Bettina , Huhtala Heini , Räty Sari , Kuokkanen Hannu , Sándor George K. , Miettinen Susanna , Suuronen Riitta
Published: November 2008

Human adipose stem cells (ASCs) combined with osteostimulative material provide an attractive approach for clinical bone regeneration. The effect of calcium phosphate (Ca‐P) surface treatment of three‐dimensional bioactive glass scaffolds on the attachment, proliferation, and osteogenic differentiation of ASCs was studied. Three types of bioactive glass scaffolds (nontreated, thick and thin Ca‐P treated) were compared. All scaffold types supported ASC attachment, spreading, and proliferation equally as detected by scanning electron microscopy, fluorescence staining, and DNA measurement. Indices of osteogenic differentiation including the expression of osteopontin and alkaline phosphatise (ALP) were consistently higher in the nontreated and thin Ca‐P‐treated scaffolds when compared with thick Ca‐P‐treated scaffolds at 2 weeks. ASCs cultured on nontreated bioactive glass scaffolds showed significantly higher ALP activity when compared with both thin and thick Ca‐P‐treated scaffolds after 1 week in culture, but these differences equalized between the three scaffolds by the 2‐week time point. In conclusion, osteogenic differentiation appears to be delayed on the Ca‐P surface‐treated scaffolds. This delay is more pronounced with thick Ca‐P treatment of the scaffolds. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res 2009
In vivoanalysis of biocompatibility and vascularization of the synthetic bone grafting substitute NanoBone®
Authors: Abshagen K. , Schrodi I. , Gerber T. , Vollmar B.
Published: November 2008

One of the major challenges in the application of bone substitutes is adequate vascularization and biocompatibility of the implant. Thus, the temporal course of neovascularization and the microvascular inflammatory response of implants of NanoBone® (fully synthetic nanocrystalline bone grafting material) were studiedin vivoby using the mouse dorsal skinfold chamber model. Angiogenesis, microhemodynamics, and leukocyte‐endothelial cell interaction were analyzed repetitively after implantation in the center and in the border zone of the implant up to 15 days. Both NanoBone® granules and plates exhibited high biocompatibility comparable to that of cancellous bone, as indicated by a lack of venular leukocyte activation after implantation. In both synthetic NanoBone® groups, signs of angiogenesis could be observed even at day 5 after implantation, whereas granules showed higher functional vessel density compared with NanoBone® plates. The angiogenic response of the cancellous bone was markedly accelerated in the center of the implant tissue. Histologically, implant tissue showed an ingrowth of vascularized fibrous tissue into the material combined with an increased number of foreign‐body giant cells. In conclusion, NanoBone®, particularly in granular form, showed high biocompatibility and high angiogenic response, thus improving the healing of bone defects. Our results underline that, beside the composition and nanostructure, the macrostructure is also of importance for the incorporation of the biomaterial by the host tissue. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res 2009
Soluble factors from neocortical astrocytes enhance neuronal differentiation of neural progenitor cells from adult rat hippocampus on micropatterned polymer substrates
Authors: Oh Jisun , Recknor Jennifer B. , Recknor Justin C. , Mallapragada Surya K. , Sakaguchi Donald S.
Published: November 2008

Rat adult hippocampal progenitor cells (AHPCs) are self‐renewing, multipotent neural progenitors that have the ability to differentiate into neurons and glia. Previously, we demonstrated that coculture of AHPCs with postnatal day 2, type 1 cortical astrocytes on laminin‐coated micropatterned polymer substrates facilitates selective neuronal differentiation of the AHPCs (Recknor et al., Biomaterials 2006;27:4098–4108). Under this condition, multidimensional cell–cell and/or cell–extracellular matrix interactions, as well as possible soluble factors released from astrocytes provided spatial and temporal control selectively enhancing neuronal differentiation and neurite alignment on topographically different regions of the same substrate. To investigate the potential role of astrocyte‐derived soluble factors as cues involved in neuronal differentiation, a noncontact coculture system was used. Under control conditions, ∼14% of the AHPCs were immunoreactive (IR) for the neuronal marker, class III β‐tubulin (TUJ1‐IR). When cocultured in physical contact with astrocytes, neuronal differentiation increased significantly to about 25%, consistent with our previous results. Moreover, under noncontact coculture conditions using Transwell® insert cultures, neuronal differentiation was dramatically increased to ∼64%. Furthermore, neurite outgrowth from neuronal cell bodies was considerably greater on the patterned substrate when compared with the nonpatterned planar substrate under noncontact coculture conditions. Taken together, our results demonstrate that astrocyte‐derived soluble factors provide cues for specific neuronal differentiation of AHPCs cultured on micropatterned substrates. In addition, a suppressive influence on neuronal differentiation appears to be mediated by contact with cocultured astrocytes. These results provide important insights into mechanisms for controlling neural progenitor/stem cell differentiation and facilitate development of strategies for CNS repair. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res 2009
Self‐setting collagen‐calcium phosphate bone cement: Mechanical and cellular properties
Authors: Moreau Jennifer L. , Weir Michael D. , Xu Hockin H. K.
Published: November 2008

Calcium phosphate cement (CPC) can conform to complex bone cavities and set in‐situ to form bioresorbable hydroxyapatite. The aim of this study was to develop a CPC‐collagen composite with improved fracture resistance, and to investigate the effects of collagen on mechanical and cellular properties. A type‐I bovine‐collagen was incorporated into CPC. MC3T3‐E1 osteoblasts were cultured. At CPC powder/liquid mass ratio of 3, the work‐of‐fracture (mean ± sd; n = 6) was increased from (22 ± 4) J/m2 at 0% collagen, to (381 ± 119) J/m2 at 5% collagen (p ≤ 0.05). At 2.5–5% of collagen, the flexural strength at powder/liquid ratios of 3 and 3.5 was 8–10 MPa. They matched the previously reported 2–11 MPa of sintered porous hydroxyapatite implants. SEM revealed that the collagen fibers were covered with nano‐apatite crystals and bonded to the CPC matrix. Higher collagen content increased the osteoblast cell attachment (p ≤ 0.05). The number of live cells per specimen area was (382 ± 99) cells/mm2 on CPC containing 5% collagen, higher than (173 ± 42) cells/mm2 at 0% collagen (p ≤ 0.05). The cytoplasmic extensions of the cells anchored to the nano‐apatite crystals of the CPC matrix. In summary, collagen was incorporated into in situ‐setting, nano‐apatitic CPC, achieving a 10‐fold increase in work‐of‐fracture (toughness) and two‐fold increase in osteoblast cell attachment. This moldable/injectable, mechanically strong, nano‐apatite‐collagen composite may enhance bone regeneration in moderate stress‐bearing applications. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res 2009
Bone augmentation by bone marrow mesenchymal stem cells cultured in three‐dimensional biodegradable polymer scaffolds
Authors: Tanaka Toshimitsu , Hirose Motohiro , Kotobuki Noriko , Tadokoro Mika , Ohgushi Hajime , Fukuchi Takeshi , Sato Junichi , Seto Kanichi
Published: November 2008

Poly‐lactic‐glycolic acid (PLGA) is a biocompatible as well as biodegradable polymer and used in various medical applications. In this study, we evaluated efficiency of the specially designed three‐dimensional porous PLGA as a scaffold for bone augmentation. First, cell attachment/proliferation, differentiation, and mineralization of Fisher 344 rat marrow mesenchymal stem cells (MSCs) cultured on the PLGA scaffold were analyzed. Viable MSCs were impregnated into pore areas of the scaffold and a moderate increase of DNA contents was seen. High alkaline phosphatase, osteocalcin content, and calcium content of MSCs in PLGA scaffolds under osteogenic differentiation conditions were seen after 14 or 21 days of culture. Subsequently, we implanted the PLGA/MSCs composites on rat calvaria bone for 30 days. Newly formed bone was seen in only the composite PLGA/MSCs implantation group, which had been precultured under osteogenic condition. We also demonstrated that the newly formed bone originated from the donor composites. These results demonstrate that the three‐dimensional PLGA scaffold can support osteogenic differentiation of MSCs, and the scaffold combined with osteogenic MSCs can be used for in vivo bone tissue augmentation. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res 2009
Assessing the binding selectivity of molecularly imprinted polymer artificial antibodies by mass spectrometry‐based profiling system
Authors: Liao Pao‐Chi , Tyan Yu‐Chang , Wang Chung‐Yao , Hsu Jing‐Fang , Chou Tse‐Chuan , Lin Hsin‐Yi
Published: November 2008

Molecularly imprinted polymer (MIP) is a technique for generating polymer‐bearing biomimetic receptors. It offers several advantages to the research such as analysis, sensors, extraction, or preconcentration of components. Myoglobin is known to be an important biological index for the diagnosis of cardiac diseases. The purpose of this research was to optimize the formation of myoglobin‐imprinted polymer (Myo‐MIP) and develop a mass spectrometry‐based profiling system for assessing the binding selectivity of artificial antibodies formed by Myo‐MIP. Experimental results showed that myoglobin and albumin were bound/absorbed onto Myo‐MIP chips and not to nonimprinted polymer (NIP) chips. Other proteins, such as histidine‐rich glycoprotein, immunoglobulins, proapolipoprotein, and leech‐derived tryptase inhibitor, were also observed but with less reproducibility from the chips. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res 2009
In vitro growth factor release from injectable calcium phosphate cements containing gelatin microspheres
Authors: Habraken W. J. E. M. , Boerman O. C. , Wolke J. G. C. , Mikos A. G. , Jansen J. A.
Published: November 2008

To improve the in vivo resorption of an injectable calcium phosphate cement (CPC) for bone tissue engineering purposes, in previous experiments macroporosity was introduced by the in situ degradation of incorporated gelatin microspheres. Gelatin microspheres are also suitable carriers for osteoinductive drugs/growth factors, where release occurs concomitantly with degradation of the hydrogel. Introduction of these microspheres into CPC can alter the release pattern of the cement, which usually shows a marginal release of incorporated drugs. The goal of this study was to determine the in vitro release characteristics of gelatin microsphere CPC. For this, recombinant human TGF‐β1, bFGF, and BMP‐2 were labeled with 125I and loaded onto gelatin type A (porcine, pI = 7.0–9.0)/type B (bovine, pI = 4.5–5.0) microspheres for a short (instant) and longer (prolonged) time before mixing them with the cement. Radioactivity of the resulting 5 or 10 wt % gelatin microsphere CPC composites was monitored for 6 weeks when subjected to proteolytic medium. Drug‐loaded CPC was used as control. Results showed that release pattern/efficiency of gelatin microsphere CPCs and CPC controls was highly dependent on the type of growth factor but unaffected by the amount of growth factor. With gelatin microsphere CPC, release was also dependent on the type of gelatin, total volume of incorporated microspheres, and loading method. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res 2009