bluuebunny/crossref_metadata_2025 huggingface dataset:
Crosslinking reaction mechanism of diisopropyl xanthogen polysulfide accelerator in bromobutyl elastomer for medical device applications
Authors: Ohbi D. S. , Purewal T. S. , Shah T. , Siores E.
Published: December 2007

The use of an accelerator based on diisopropyl xanthogen polysulfide (DIXP) to formulate bromobutyl elastomer (BIIR‐DIXP) compositions for sealing medical devices was published in the Journal of Applied Polymer Science (Ohbi, D. S.; Pureval, T. S.; Shah, T.; Siores, E. 2007, 106, 526). In this publication, a reaction scheme for the DIXP accelerator in situ with BIIR is proposed. It is based on the evolved volatile chemical species determined during the curing reaction of BIIR‐DIXP composition, and is formulated in the light of generally accepted mechanism of crosslinking elastomers using sulfur‐based accelerators. The volatile chemical species were determined using coupled thermogravimetric infrared analysis (TGA‐IR) and head space gas chromatography mass spectroscopy (GC‐MS) analysis. The main volatiles evolved during the curing reaction were carbonyl sulfide, carbon disulfide, and isopropyl bromide. These are considered to be associated with the formation of the active rubber‐bound DIXP sulfurating species required for the crosslinking reaction. Analysis of the acetone extract of cured BIIR‐DIXP also showed that the DIXP is totally consumed during the cure reaction, and the formulation is largely free of cure reaction byproducts. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Structure and metal type effects on cure kinetics of DGEBA with benzil bisthiosemicarbazone complexes
Authors: Ghaemy Mousa , Behmadi Hossein
Published: December 2007

The curing reaction kinetics of the diglycidyl ether of bisphenol A‐ (DGEBA) based epoxy was investigated according to the change of curing agents. Complex curing agents based on Ni(II) and Cu(II) chelates with benzil bisthiosemicarbazone (LH6) as a ligand was studied using differential scanning calorimetry. The curing reaction was characterized by high‐activation energies (Ea), cure onset (Ti), and peak maximum (Tp) temperatures. Dynamic kinetic parameters were calculated by using Kissinger and Ozawa methods. For the NiLH6Cl2, CuLH6Cl2, and LH6 the average values of Ea were calculated to be 165.16, 165.92, and 115.75 kJ/mol, respectively. For the NiLH6Cl2 systems, their activation energies at 40 and 30 phr are equal. The Ti and Tp of the DGEBA/NiLH6Cl2 system are lower than those of DGEBA/CuLH6Cl2 system. These results indicate that NiLH6Cl2 has a higher reactivity toward epoxy resin at the beginning of the curing reaction. The effect of hardener concentration, heating rate, and type of metal ion on the cure kinetic parameters and the shape of DSC thermograms were investigated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Synthesis and characterization of fullerene grafted poly(ε‐caprolactone)
Authors: Kai Weihua , Hua Lei , Dong Tungalag , Pan Pengju , Zhu Bo , Inoue Yoshio
Published: December 2007

The fullerene grafted poly(ε‐caprolactone) (PCL) was successfully synthesized with a graft efficiency of 80%. The fullerene moieties grafted onto the PCL chain aggregate into 1–2 μm particles so that a physical pseudo‐network is formed. Because of the existence of the network structure, the fullerene grafted PCL film can retain its shape at much higher temperatures than that of pure PCL film, as observed in dynamic mechanical tests. It shows a hydrophobic gelling behavior in chloroform solution. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Organocatalytic Enantioselective One‐Pot Synthesis and Application of Substituted 1,4‐Dihydropyridines—Hantzsch Ester Analogues
Authors: Franke Patrick T. , Johansen Rasmus L. , Bertelsen Søren , Jørgensen Karl Anker
Published: December 2007

An easy and simple one‐pot approach for the formation of optically active substituted 1,4‐dihydropyridines by using asymmetric organocatalysis is presented. The one‐pot reaction of α,β‐unsaturated aldehydes with β‐diketones or β‐ketoesters and primary amines gives optically active 2,3‐substituted 1,4‐dihydropyridines in moderate yields and with enantioselectivities up to 95 % ee. It is also demonstrated that the optically active 1,4‐dihydropyridines can be used in situ for the direct enantioselective reduction of, for example, α‐ketoesters with high enantioselectivity.
Conformational Preference and Potential Templates ofN‐Methylated Cyclic Pentaalanine Peptides
Authors: Chatterjee Jayanta , Mierke Dale F. , Kessler Horst
Published: December 2007

SystematicN‐methylation of all peptide bonds in the cyclic pentapeptide cyclo(‐D‐Ala‐Ala4‐) has been performed yielding 30 differentN‐methylated derivatives, of which only seven displayed a single conformation on the NMR time scale. The conformation of these differentiallyN‐methylated peptides was recently reported by us (J. Am. Chem. Soc.2006,128, 15 164–15 172). Here we present the conformational characterization of nine additionalN‐methylated peptides from the previous library which are not homogeneous but exist as a mixture in which at least one conformation is preferred by over 80 %. The structures of these peptides are investigated employing various 2D‐NMR techniques, distance geometry calculations and further refined by molecular dynamics simulations in explicit DMSO. The comparison of the conformation of these nine peptides and the seven conformationally homogeneous peptides allow us to draw conclusions regarding the influence ofN‐methylation on the peptide backbone of cyclic pentapeptide of the class cyclo(‐D‐Ala‐Ala4‐). Here we present the different conformational classes of the peptides arising from the definitive pattern ofN‐methylation which can eventually serve as templates for the design of bioactive peptides.
Pd PEPPSI‐IPr‐Mediated Reactions in Metal‐Coated Capillaries Under MACOS: The Synthesis of Indoles by Sequential Aryl Amination/ Heck Coupling
Authors: Shore Gjergji , Morin Sylvie , Mallik Debasis , Organ Michael G.
Published: December 2007

A method has been devised for the microwave‐assisted, continuous‐flow preparation of indole alkaloids by a two‐step aryl amination/cross‐coupling sequence of bromoalkenes and 2‐bromoanilines. This process requires both the presence of a metal‐lined flow tube (a 1180 micron capillary) and the Pd PEPPSI‐IPr catalyst; without either, the catalyst or the film, there is zero turnover of this catalytic process. A silver film has been shown to provide some conversion (48–62 %), but optimal results (quantitative) across a variety of bromoalkenes and bromoanilines were achieved by using a highly porous palladium film. Possible roles for the Pd film are considered, as is the interplay of the catalyst and the film.
A class of methods and algorithms for the analysis of successive origination of holes in a pre‐stressed viscoelastic body. Finite strains
Authors: Levin V. A. , Zingerman K. M.
Published: December 2007

A class of methods and algorithms for the solution of two‐dimensional quasi‐static problems of stress distribution near holes is considered for finite strains. It is assumed that the holes have originated successively in a previously loaded body made of incompressible viscoelastic material. The problem is formulated on the basis of the theory of repeated superposition of large deformations. The mechanical properties of the material are described by convolution integral relations with the kernel of weak singularity. The solution is obtained using the approximate analytical methods (Signorini's technique, Laplace transform, and Muskhelishvili's technique). A special‐purpose software for analytical calculations is used for the solution. Some numerical results are presented. Copyright © 2007 John Wiley & Sons, Ltd.
Self‐Assembling Nanoparticles at Surfaces and Interfaces
Authors: Kinge Sachin , Crego‐Calama Mercedes , Reinhoudt David N.
Published: December 2007

Nanoparticles are the focus of much attention due to their astonishing properties and numerous possibilities for applications in nanotechnology. For realising versatile functions, assembly of nanoparticles in regular patterns on surfaces and at interfaces is required. Assembling nanoparticles generates new nanostructures, which have unforeseen collective, intrinsic physical properties. These properties can be exploited for multipurpose applications in nanoelectronics, spintronics, sensors, etc. This review surveys different techniques, currently employed and being developed, for assembling nanoparticles in to ordered nanostructures. In this endeavour, the principles and methods involved in the development of assemblies are discussed. Subsequently, different possibilities of nanoparticle‐based nanostructures, obtained in multi‐dimensions, are presented.
Visualizing the Frontier Orbitals of a Conformationally Adapted Metalloporphyrin
Authors: Weber‐Bargioni Alexander , Auwärter Willi , Klappenberger Florian , Reichert Joachim , Lefrançois Simon , Strunskus Thomas , Wöll Christof , Schiffrin Agustin , Pennec Yan , Barth Johannes V.
Published: December 2007

We present a molecular‐level study of the geometric and electronic properties of CoII tetraphenylporphyrin molecules adsorbed on the Cu(111) surface. A combination of low‐temperature scanning tunneling microscopy and near‐edge X‐ray absorption fine structure observations reveals how the metal substrate induces a conformational adaptation into a distorted saddle‐shaped geometry. By scanning tunneling spectroscopy we identified the discrete energy levels of the molecule and mapped their spatial electron‐density distributions. These results, along with a simple theoretical description, provide a direct correlation between the shape of frontier molecular orbitals and intramolecular structural features.
Environmental quality and the cost of environmental regulation: a comparison of Scotland with the international community
Authors: Le Roux Jean , Williams Evan , Staines Andrew , Bergmann Ariel
Published: December 2007

In today's global economy, assessing costs of compliance is crucial to understand how environmental regulations influence firms' behaviour and in particular their ability to compete at an international level. A three step methodology is used to conduct a comparison of Scotland's industry with the international community. The first step compares environmental protection expenditures among the European Community. The second step uses the Environmental Regulatory Regime Index developed by Porter and Esty to compare regulatory quality among 71 nations. The final step compares Scotland's environmental quality with the international community based on three criteria: SO2, PM10 and energy efficiency. Relative to the countries used in this research, Scotland is found to have a high quality regulatory regime, low costs of compliance for industry and a mixture of moderate to high environmental quality. Because significant deficiencies exist in the data, some uncertainties remain in the results. Published in 2007 with the permission of the Controller of Her Majesty's Stationery Office and the Queen's Printer for Scotland.
A Chemoenzymatic, Preparative Synthesis of the Isomeric Forms of p‐Menth‐1‐en‐9‐ol: Application to the Synthesis of the Isomeric Forms of the Cooling Agent 1‐Hydroxy‐2,9‐cineole
Authors: Serra Stefano , Fuganti Claudio , Gatti Francesco G.
Published: December 2007

A preparative‐scale synthesis of the four p‐menth‐1‐en‐9‐ol isomers 2a–5a has been achieved by means of two chemoenzymatic processes. Both synthetic pathways start from the enantiomeric forms of limonene that are converted into p‐mentha‐1,8‐dien‐9‐al isomers 12 and 15. The baker's yeast mediated reduction of the latter aldehydes afforded compounds 3a and 5a, respectively, with very high enantioselectivity. Moreover, chemical reduction of 12 and 15 gives the mixtures of enantiopure diastereoisomers 2a/3a and 4a/5a, respectively. PPL (Porcine pancreas lipase) mediated resolution of the latter mixtures followed by fractionating crystallization of derivatives 2b–5b allowed the enantio‐ and diastereoisomerically pure alcohols 2a–5a to be obtained. Compounds 2a–5a have then been used as starting materials for the preparation of four isomers of the cooling agent 1‐hydroxy‐2,9‐cineole (6–9). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Metrological Aspects of Activity Measurements in Mixed Electrolytes by Ion‐Selective Electrodes
Authors: Wunderli Samuel , Andres Hanspeter
Published: December 2007

Based on the model equation for the measurand analyte activity, all significant sources of uncertainty are identified, their magnitude estimated from published and experimental data and finally combined to give the uncertainty in the reported value of the analyte activity. It is found that the combined uncertainty is dominated by the uncertainties in the diffusion potential EJ and the time‐dependent response behavior κ of the sensor. Using Henderson's approach EJ is calculated not to vary more than 150 μV for physiological analytes in contact with a 3 M KCl reference solution. The stability of the reference electrode as well as the flow characteristics in the vicinity of the sensing element greatly influence the response time of the sensor. By minimizing the mentioned contributions of EJ and κ in the uncertainty budget, combined uncertainties for activity values in the range of 2% are feasible for univalent ions.
Mathematical Model of Current‐Polarized Ionophore‐Based Ion‐Selective Membranes: Large Current Chronopotentiometry
Authors: Zook Justin M. , Buck Richard P. , Gyurcsányi Róbert E. , Lindner Ernő
Published: December 2007

The properties of ionophore‐based ion‐selective membranes were investigated theoretically and experimentally for the first time in large‐current chronopotentiometric experiments. In these experiments, when either the free ionophore or the ion‐ionophore complex concentration drops to zero at one of the membrane boundaries, a characteristic drop in voltage (breakpoint) appears in the chronopotentiometric transients at a transition time τ. Based on a mathematical model of current polarized membranes, theoretical equations were derived and tested. These equations describe the correlation between the transition time τ and the concentration of free ionophore, the concentration of ion‐ionophore complex, and the diffusion coefficients of species in the membrane. The simulated concentration profiles correlated well with concentration profiles recorded experimentally prior to the transition time using spectroelectrochemical microscopy (SpECM). Diffusion coefficients calculated from (i) the transition times, (ii) curve fitting, and (iii) the initial ohmic resistance of the studied membranes were also compared.
Amperometric Nitrosothiol Sensor Using Immobilized Organoditelluride Species as Selective Catalytic Layer
Authors: Hwang Sangyeul , Cha Wansik , Meyerhoff Mark E.
Published: December 2007

A new amperometric sensor capable of responding to various biological S‐nitrosothiol species (RSNOs) is described. The sensor is prepared using an organoditelluride‐tethered poly(allyamine hydrochloride) (PAH) polymer crosslinked within a dialysis membrane support mounted at the distal surface of an amperometric NO probe. The surface immobilized organoditelluride layer serves as a selective catalyst to decompose various RSNO species to NO in the presence of a thiol reducing agent added to the sample. The proposed sensor responds directly and reversibly to various low molecular weight (LMW) RSNOs in the range of 0.1 μM to 10 μM with nearly equal sensitivity. The main advantage of this sensor over previously reported Cu(II/I) and organodiselenium‐based RSNO sensors is its long operational life‐time (at least one month). A discussion regarding solution phase transnitrosation reactions potentially allowing the measurement of higher molecular weight S‐nitrosoproteins is provided, along with data showing preliminary results in this direction. Further, the direct detection of endogenous RSNO species in diluted fresh whole sheep blood is also demonstrated using this new sensor.
Voltammetric (Micro)Electrodes for the In Situ Study of Fe2+ Oxidation Kinetics in Hot Springs and S2O$\rm{ _3^{2 - } }$ Production at Hydrothermal Vents
Authors: Mullaugh Katherine M. , Luther George W. , Ma Shufen , Moore Tommy S. , Yücel Mustafa , Becker Erin L. , Podowski Elizabeth L. , Fisher Charles R. , Trouwborst Robert E. , Pierson Beverly K.
Published: December 2007

We have used solid‐state Au/Hg voltammetric electrodes to understand redox and biogeochemical processes in hot spring and deep sea hydrothermal environments. These electrodes are non‐specific and have the capability of measuring simultaneously a suite of chemical species including several of the principal redox species involved in early diagenesis (O2, Mn2+, Fe2+, H2S/HS−, and I−) as well as some Fe species (FeS and Fe3+) and sulfur species (Sx2− and S2O$\rm{ _3^{2 - } )}$. Here we demonstrate how in situ data obtained in complex environments can be used to study specific iron and sulfur reactions and processes at (sub)millimeter to centimeter resolution and over short time scales. Examples include the oxidation of Fe2+ by O2 produced by cyanobacterial mats in Yellowstone National Park hot springs and the formation of S2O$\rm{ _3^{2 - } }$ in diffuse flow waters from the hydrothermal vents at Lau Basin. In one example, profiles of redox species in cyanobacterial mats from Yellowstone National Park hot springs show that in the light dissolved Fe2+ is completely removed from the source waters as cyanobacterial mats produce O2 and oxidize the Fe2+. Performing kinetic experiments in the dark and light at the depth of maximum O2 production indicates that the decay of Fe2+ follows a zero order rate law consistent with photosynthesis as the source of O2. These dynamic environments show how kinetic data can be obtained in situ and be used to understand the interactions between biology and chemistry. We know of no other analytical technique that can provide this information in both clear and turbid waters on the time scales (seconds) observed.
Amperometric Enzyme‐Based Biosensor for Direct Detection of Formaldehyde in the Gas Phase: Dependence on Electrolyte Composition
Authors: Achmann Sabine , Hämmerle Martin , Moos Ralf
Published: December 2007

An enzymatic sensor detecting the analyte formaldehyde directly from the gas phase is under investigation. In contrast to existing systems, it enables the quantification of the analyte without prior sampling or accumulation and thus can be used as an online system to monitor the formaldehyde concentration in ambient air. The amperometric sensor depends on the enzymatic conversion of the analyte using formaldehyde dehydrogenase from P. putida [EC. 1.2.1.46] as the recognition element. It shows a linear response curve up to 15 ppm, with a detection limit of 0.03 pm (S/N=3). In order to optimize the sensor performance the electrolyte composition within the sensor was varied with respect to pH value, buffer concentration and the addition of Ca2+ and Mg2+ ions. To elucidate the influence of the mediator and the enzyme on the sensor performance the stability and activity of the electrochemical mediator and the enzyme alone was examined separately in these different electrolytes.
On‐line concentration of proteins by SDS‐CGE with LIF detection
Authors: Yu Cheng‐Ju , Chang Hui‐Chiu , Tseng Wei‐Lung
Published: December 2007

We present a simple approach for on‐line concentration of SDS‐protein complexes by using poly(vinyl alcohol) (PVA) solution in CGE. In comparison to the coated capillary, the presence of EOF in CGE omitted the need to fill the capillaries with polymer solutions prior to the analysis. More importantly, we found that highly reproducible separation of eight proteins by 3.5% PVA was achieved between runs and without the regeneration of high bulk EOF; the RSD of migration times was less than 0.7%. To further improve the concentration sensitivity, neutral PVA was introduced into the capillary with the help of EOF to act as sieving matrix. The occurrence of stacking at the boundary between the PVA and the sample zone is mainly due to the retardation of proteins by PVA. As a result, the LODs at an S/N of 3 for SDS–protein complexes are of the order of sub‐nM to several nM. For example, the LOD for BSA is 0.78 nM, which is a 91‐fold sensitivity enhancement over the normal injection. In addition, our stacking method has been applied to the analyses of proteins in Escherichia coli cells. The peak for β‐galactosidase (E. coli) was observed after 0.1 μM β‐galactosidase was spiked into the E. coli samples.
Two‐color electrophoretic immunoassay for simultaneous measurement of insulin and glucagon content in islets of Langerhans
Authors: Guillo Christelle , Roper Michael G.
Published: December 2007

A multianalyte CE competitive immunoassay using two‐color detection was developed to measure insulin and glucagon in islets of Langerhans. Insulin was quantified with FITC‐insulin (Ins*) and anti‐insulin antibodies (Ins Ab) and glucagon was quantified with Cy5‐glucagon (Glu*) and anti‐glucagon antibodies (Glu Ab). A 3 mW Ar+ laser at 488 nm and a 25 mW laser diode at 635 nm were used to excite FITC and Cy5, respectively. Fluorescence was split with a half‐silvered mirror and passed through a 520 ± 20 nm bandpass filter or a 663 nm longpass filter for the detection of insulin and glucagon, respectively. The two‐color detection format enabled independent quantitation of both analytes even with concentrations of insulin immunoassay reagents 20‐fold higher than glucagon reagents. Simultaneous calibration curves were generated and used to determine insulin and glucagon content in islets of Langerhans. Amounts of insulin and glucagon were 56.6 ± 3.2 and 1.0 ± 0.5 ng/islet, respectively. LODs were 7 nM insulin and 3 nM glucagon. The assay will be applicable to fast monitoring of multiple peptides secreted from islets of Langerhans and can be applied to other systems for the quantitation of multiple analytes with large differences in concentrations.
Determination of sulfophenyl carboxylic acids in agricultural groundwater samples by CE with ultraviolet absorption detection
Authors: Jiménez‐Díaz Inmaculada , Ballesteros Oscar , Vílchez José Luis , Navalón Alberto
Published: December 2007

An analytical method for the determination of six sulfophenyl carboxylic acids, namely (p‐sulfophenyl)acetic, 2‐(p‐sulfophenyl)propionic, 2‐(p‐sulfophenyl)butyric, 3‐(p‐sulfophenyl)butyric, 4‐(p‐sulfophenyl)butyric, and 5‐(p‐sulfophenyl)valerianic acid, in agricultural irrigation water samples was developed. It involves an SPE procedure, an on‐line preconcentration normal stacking mode and subsequent separation and determination using CE with UV detection (CE‐UV). p‐Sulfobenzoic acid was used as internal standard. The compounds were separated with an uncoated capillary and a 25 mM ammonium acetate/acetic acid buffer solution (pH 5.5) with 2‐propanol (30% v/v) and 0.75 mM CTAB. Analyses were run at −25 kV, 25°C, and 100 s of hydrodynamic injection with UV detection at 225 nm. Quantification limits found ranged between 4 and 6 ng/mL. The proposed method was validated using a recovery assay. It was satisfactorily used for the determination of these compounds in groundwater samples to track down the biodegradation of linear alkylbenzene sulfonates in an agricultural soil from the fertile plain of Granada (Spain).
CE combined with rolling circle amplification for sensitive DNA detection
Authors: Li Ni , Li Jishan , Zhong Wenwan
Published: December 2007

Here we describe an assay which combines CE with rolling circle amplification (RCA) for sensitive DNA detection and quantification. RCA is an isothermal DNA replication technique that generates a long ssDNA with tandem repeats. It requires simpler temperature control in reaction and offers higher sequence specificity and greater quantitation capability compared to other amplification technologies. In this study, RCA amplified the DNA target via a circular template, and the product was digested into monomers for CE analysis. Less than 2 fmol of the DNA target could easily be detected using this RCA‐CE assay and the assay has a dynamic range of two orders of magnitudes. Moreover, simultaneous detection of both the target DNA and the internal standard was achieved by designing two padlock probes with different sizes, which could significantly improve the quantification accuracy. The RCA‐CE assay is easy to perform, readily adaptable for detection of multiple targets because of the high resolution power of CE, and is compatible with other applications employing RCA as a signal amplification tool. Additionally, this assay can be used with a capillary array system to perform sensitive, high‐throughput genetic screening.
Nanofibrous matrices of poly(lactic acid) and gelatin polymeric blends for the improvement of cellular responses
Authors: Kim Hae‐Won , Yu Hye‐Sun , Lee Hae‐Hyoung
Published: December 2007

Substrates with a nanofibrous morphology are considered as a prospective matrix to populate and support cells in the tissue regeneration area. Although the nanofibers made of synthetic degradable polymers, including poly(lactic acid) (PLA), have been well studied, their poor cell affinity has restricted wider applications. Herein, we produced blending nanofibers made of PLA and gelatin to improve the cellular responses of PLA. For this, both PLA and gelatin were dissolved in an organic solvent, varying the compositions of PLA:gelatin at 1:3 and 1:1 by weight, and the solutions were electrospun into nanofibers. At all compositions, nanofibers could be successfully generated with diameters of approximately hundreds of nanometers. The addition of gelatin into PLA markedly improved the wettability of the nanofibrous substrate. The osteoblastic cells attached and spread well on all the blending nanofibers and pure PLA. In particular, the cellular growth was significantly higher on the gelatin‐blended PLA than on the pure PLA nanofiber. On the basis of this study, the PLA/gelatin blending polymeric nanofibers are considered to be useful as a bone cell supporting matrix in the tissue regeneration area. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Porous β‐tricalcium phosphate/collagen composites prepared in an alkaline condition
Authors: Zou Chao , Weng Wenjian , Cheng Kui , Du Piyi , Shen Ge , Han Gaorong , Guan Binggang , Yan Weiqi
Published: December 2007

Bone substitute materials with natural bone‐like structure are considered to be favorable for bone regeneration. In this work, porous β‐tricalcium phosphate (β‐TCP)/collagen composite consisting of bone‐like microstructural units was prepared using nanosized β‐TCP particles and alkaline‐disassembled collagen. The resulting composite showed a good interconnecting porous structure with ∼90% porosity and 100 ∼ 300 μm pore size. The pore walls were dense, and the combination status of collagen and nanosized β‐TCP particles demonstrated that nanosized β‐TCP particles tightly connected collagen microfibrils as a bone‐like microstructural unit. MTT and alkaline phosphatase (ALP) assays showed that the porous composite had enhanced effects on cellular proliferation and activity of osteoblast compared with a control of pure collagen. It is suggested that the adoption of nanosized β‐TCP particles is a main contribution to the formation of the composite with a bone‐like microstructural unit, and the unique microstructure could be a main role for the composite to have the positive influence on osteoblast cell proliferation. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Mechanism of calcium disilicide‐induced calcification of crystalline silicon surfaces in simulated body fluid under zero bias
Authors: Seregin Vladimir V. , Coffer Jeffery L.
Published: December 2007

A dry‐etch spark ablation method was used to produce calcium disilicide (CaSi2/Si) layers on silicon surfaces, and their biomineralization under zero bias was followed by means of scanning electron microscopy, X‐ray energy dispersive analysis, and Raman spectroscopy. CaSi2/Si wafers are bioinert at 25°C and bioactive at 37°C. Mechanistic insights regarding biomineralization were derived from an analysis of film growth morphology and chemical composition after various soaking periods in standard simulated body fluid (SBF). Changes in CaSi2 calcification behavior as a function of reaction temperature and pH, SBF concentration, and various surface modification processes were also employed for this purpose. During CaSi2/Si calcification under zero bias, calcium phosphate (CaP) growth is strongly dependent on the structural degradation of CaSi2 grains. Surface silanol groups, initially present on the as‐prepared material, cannot induce CaP nucleation, which begins only upon delamination of CaSi2 layers. The calcium phosphate phases, which are present during various growth stages, possibly include a combination of Mg‐substituted whitlockite, monetite, and tricalcium phosphate. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Biodegradable and thermoreversible hydrogels of poly(ethylene glycol)‐poly(ε‐caprolactone‐co‐glycolide)‐poly(ethylene glycol) aqueous solutions
Authors: Jiang Zhiqiang , Hao Jianyuan , You YuJing , Liu Yan , Wang Zhenhong , Deng Xianmo
Published: December 2007

The aqueous solutions of triblock copolymers of poly(ethylene glycol)–poly(ϵ‐caprolactone‐co‐glycolide)–poly(ethylene glycol) [PEG–P(CL‐GA)–PEG] undergoing sol–gel transition as the temperature increases from 20 to 60°C were successfully prepared. The thermogelling block copolymers were synthesized by subtle control of the hydrophilic/hydrophobic balance and the chain microstructures. The amphiphilic block copolymer formed micelles in aqueous solution, and the micelle aggregated as the temperature increased. The sol–gel transition of the copolymer aqueous solutions was studied focusing on the structure–property relationship. GA was incorporated into the polymer chain to prevent crystallization of PCL component and increase the polymer degradation. It is expected to be a promising long‐term delivery system for pH‐sensitive drugs, proteins, and genes. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Adhesion of protein residues to substituted (111) diamond surfaces: An insight from density functional theory and classical molecular dynamics simulations
Authors: Borisenko Konstantin B. , Reavy Helen J. , Zhao Qi , Abel Eric W.
Published: December 2007

Protein‐repellent diamond coatings have great potential value for surface coatings on implants and surgical instruments. The design of these coatings relies on a fundamental understanding of the intermolecular interactions involved in the adhesion of proteins to surfaces. To get insight into these interactions, adhesion energies of glycine to pure and Si and N‐doped (111) diamond surfaces represented as clusters were calculated in the gas phase, using density functional theory (DFT) at the B3LYP/6‐31G* level. The computed adhesion energies indicated that adhesion of glycine to diamond surface may be modified by introducing additional elements into the surface. The adhesion was also found to induce considerable change in the conformation of glycine when compared with the lowest‐energy conformer of the free molecule. In the Si and N‐substituted diamond clusters, notable changes in the structures involving the substituents atoms when compared with smaller parent molecules, such as 1‐methyl‐1‐silaadamantane and 1‐azaadamantane, were detected. Adhesion free energy differences were estimated for a series of representative peptides (hydrophobic Phe‐Gly‐Phe, amphiphilic Arg‐Gly‐Phe, and hydrophilic Arg‐Gly‐Arg) to a (111) diamond surface substituted with different amounts of N, Si, or F, using molecular dynamics simulations in an explicit water environment employing a Dreiding force field. The calculations were in agreement with the DFT results in that adsorption of the studied peptides to diamond surface is influenced by introducing additional elements to the surface. It has been shown that, in general, substitution will enhance electrostatic interactions between a surface and surrounding water, leading to a weaker adhesion of the studied peptides. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 86A: 1113–1121, 2008
Mechanical and chemical characteristics of an autologous glue
Authors: De Somer Filip , Delanghe Joris , Somers Pamela , Debrouwere Maarten , Van Nooten Guido
Published: December 2007

The study evaluates the mechanical and chemical characteristics of autologous surgical glue made by mixing ultrafiltered plasma with glutaraldehyde (GTA). Human albumin 200 g/L mixed with different concentrations of GTA (25, 50, 75, or 100 g/L) was used as a single protein set‐up for testing tensile strength, elasticity, and rate of crosslinking. Subsequently, ultrafiltered canine or human plasma to obtain autologous glue replaced human albumin. BioGlue, a surgical glue, and Tissucol Duo, a fibrin sealant, were used as controls. Tensile strength of human albumin 200 g/L mixed with 75 g/L GTA is 825 ± 109 N versus 672 ± 167 N for BioGlue. Ultrafiltered canine plasma showed a maximum tensile strength of 634 ± 137 N when mixed with GTA 75 g/L. For human plasma, the maximum tensile strength of 436 ± 69 N was reached after mixing with GTA 25 g/L. Autologous glue had a higher elasticity of 144 ± 66 N versus 322 ± 104 N for BioGlue at maximum load. Autologous glues for vascular repair can be easily prepared out of the patient's plasma. The optimal characteristics, compared to BioGlue, are obtained for ultrafiltered canine and human plasma by mixing with a GTA concentration of 50–75 g/L and 25–50 g/L, respectively. The autologous glue will exert less tensile strength than BioGlue but has a better compliance. In case where no plasma can obtained from the patient, mixing human albumin 200 g/L with GTA 75 g/L can be an alternative to BioGlue. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Paclitaxel release from single and double‐layered poly(DL‐lactide‐co‐glycolide)/poly(L‐lactide) film for biodegradable coronary stent application
Authors: Lao Luciana Lisa , Venkatraman Subbu S.
Published: December 2007

Our laboratory has been developing a completely biodegradable coronary stent which is made of bilayers of biodegradable polyesters. This article presents the preliminary work done to exploit the drug delivery potential of such a polymeric stent. An antiproliferative drug (paclitaxel) was added either only to the top layer or to both layers and the in vitro release profiles were monitored for up to 90 days. Within 90 days, the measured paclitaxel release was almost entirely from the P(DL)LGA layer. In general, the release profiles show three distinct stages: (a) extremely slow diffusional release, (b) accelerated diffusion‐degradation release, and (c) saturation. Separate degradation studies (water absorption, molecular weight reduction, weight loss, and surface topography) were also conducted to better understand the observed release behavior. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Therapeutic plasma exchange performed in parallel with extra corporeal membrane oxygenation for antibody mediated rejection after heart transplantation
Authors: Jhang Jeffrey , Middlesworth William , Shaw Rose , Charette Kevin , Papa Joey , Jefferson Rashida , Torloni Antonio S. , Schwartz Joseph
Published: December 2007

We report on the feasibility, safety, and efficacy of performing therapeutic plasmapheresis (TPE) in parallel with extracorporeal membrane oxygenation (ECMO) to alleviate antibody mediated rejection (AMR) after heart transplantation. Two pediatric and one adult patient presented with severe congestive heart failure and respiratory distress after heart transplantation and required ECMO support. TPE was initiated to treat AMR while patients remained on ECMO. Each patient received three to five procedures either every day or every other day. One equivalent total plasma volume (TPV) was processed for each procedure (patient TPV + ECMO extracorporeal TPV). A total of 13 TPE procedures were performed with 12 procedures completed without complications or adverse events; one procedure was terminated before completion because of cardiac arrhythmia. Anti‐HLA antibody titers decreased after TPE in all three patients. Ventricular function improved and ECMO was discontinued in 2 of 3 patients. Performing large volume TPE with a processed volume up to 2.5 times the patient's TPV is well tolerated in both pediatric (≤ 10 kg) and adult patients. TPE in parallel with ECMO is feasible, safe, and may be measurably effective at reducing anti‐HLA antibodies and should be considered as part of the treatment for patients with early AMR after heart transplantation. J. Clin. Apheresis, 2007. © 2007 Wiley‐Liss, Inc.
Performance of a new separator system for routine autologous hematopoietic progenitor cell collection in small children
Authors: Witt Volker , Beiglböck Elisabeth , Ritter Robert , Würth Marianne , Peters Christine , Ladenstein Ruth , Gadner Helmut , Fritsch Gerhard
Published: December 2007

The AMICUS™ system was recently introduced for peripheral blood stem cell (PBSC) aphereses in adults. We conducted a single center field evaluation to obtain data about the performance of this system in children with a body weight (bw) < 25 kg. Results of blood priming procedures were compared to historical data obtained with the Fenwal CS3000+ (CS 3000). From August, 2001 to February, 2007, 47/178 (26%) PBSC aphereses procedures were performed in our institution with the AMICUS™ system in 35 small patients (median bw 13.9 kg; range 6.7–24; age 2.78 years; range 0.97–7.06). The patients suffered from various malignant primary diseases or recurrences. We primed the system with packed RBC in case of >30% dilution of the RBC volume (n = 31) or with saline (n = 16). Compared to the CS3000, the AMICUS™ revealed comparable collection efficiencies (CE) for CD34+ cells (median 67%, range 26–120), lymphocytes (75%, 25–138), monocytes (54%, 23–173), and granulocytes (10%, 1.5–36), MNC (57% 24–125), but a significantly higher erythrocyte and granulocyte, and a lower platelet CE. There was a significant negative correlation between total leukocyte count and CE for MNC (r = −0.566; P < 0.001) and CD34+ cells (r = −0.517; P < 0.001). There was no significant statistical or clinical difference between the CE in blood‐primed procedures and saline‐primed procedures. With the AMICUS™ we saw statistically less citrate reactions compared to the CS 3000. We conclude that the AMICUS™ system is safe and efficient to harvest PBSC on a routine basis in pediatric patients, even in children ≤10 kg bw. J. Clin. Apheresis, 2007. © 2007 Wiley‐Liss, Inc.
Tyrosine phosphorylation controls nuclear localization and transcriptional activity of Ssdp1 in mammalian cells
Authors: Dey‐Guha Ipsita , Malik Nasir , Lesourne Renaud , Love Paul E. , Westphal Heiner
Published: December 2007

The LIM‐HD proteins interact with different cofactors, including Ssdp1 to regulate development in a diverse range of species. The single stranded DNA binding protein (Ssdp1) is a member of an evolutionarily conserved family of proteins that regulate critical transcriptional processes during embryonic development. Ssdp1 is localized predominantly in the cytoplasm of 293T cells but is translocated to the nucleus when co‐transfected with Lck, a member of the Src family of non‐receptor tyrosine kinases. The Src tyrosine kinase inhibitor PP2 blocked the nuclear translocation of Ssdp1. Western blot analysis showed that co‐expression of Ssdp1 and Lck in 293T cells induces Ssdp1 phosphorylation. Mutation of the Ssdp1 N terminal tyrosine residues 23 and 25 markedly reduced both the phosphorylation and the nuclear localization of Ssdp1. Lck enhanced the transcriptional activity of Ssdp1 in the context of known components of a LIM‐homeodomain (LIM‐HD)/cofactor complex. We propose that phosphorylation involving N‐terminal tyrosine residues of Ssdp1 is a means of regulating its nuclear localization and subsequent transcriptional activation of LIM‐HD complexes. J. Cell. Biochem. 103: 1856–1865, 2007. © 2007 Wiley‐Liss, Inc.
Disease‐modifying effects of Glucosamine HCl involving regulation of metalloproteinases and chemokines activated by interleukin‐1β in human primary synovial fibroblasts
Authors: Lu Hsien‐Tsung , Liang Yu‐Chih , Sheu Ming‐Thau , Ho Hsiu‐O , Lin Ya‐Ting , Hsieh Ming‐Shium , Chen Chien‐Ho
Published: December 2007

The purpose of this study was to investigate the possible involvement of synovium in cartilage destruction in osteoarthritis (OA) patients. Using human primary synovial fibroblasts (HPSFs), we examined the effects of glucosamine (GLN) on the regulation of the expression of matrix metalloproteinases (MMP‐1, ‐2, and ‐13) and chemokines (IL‐8, MCP‐1, and RANTES) as well as the involvement of MAPK signal pathways (JNK, ERK, and p‐38) and the transcription factor of NF‐κB on the present or absence of interleukin (IL)‐1β. Our experiments showed that protein production and mRNA expressions of MMP‐1, MMP‐3, MMP‐13, IL‐8, MCP‐1, and RANTES were downregulated by treatment with glucosamine in HPSFs. The results further showed that GLN could inhibit IκBα phosphorylation and IκBα degradation leading to inhibition of the translocation of NF‐κB to nuclei. However, GLN upregulated MAPKs pathways in HPSFs cells with or without IL‐1β. The results suggest that the inhibition of MMP‐1, ‐3, and ‐13 expressions as well as IL‐8, MCP‐1, and RANTES productions by GLN might mediate suppression of NF‐κB signal pathways, and HPSFs seem to have a potential functions as an alternative source of MMPs and chemokines for inducing the degradation of cartilage in OA. J. Cell. Biochem. 104: 38–50, 2008. © 2007 Wiley‐Liss, Inc.
On the application of ‘seeding’ techniques in the primary separation of plasmid DNA from neutralised E. coli lysates
Authors: Theodosiou Eirini , Thomas Owen RT
Published: December 2007

BACKGROUND: Initial extraction of plasmid DNA from Escherichia coli and its separation from host‐derived contaminants is a difficult task to perform. Here, we examine the application of particle ‘seeding’ solid–liquid separation methods for primary recovery of plasmid DNA from neutralised alkaline cell lysates.

RESULTS: Planting magnetic particle ‘seeds’ during cell lysis resulted in enhanced phase separation, facile magnetic separation of the floc, slight improvements in plasmid purity, but diminished plasmid recoveries. When CaCO3‐coated low‐density microspheres were seeded into flocs, phase separation was impaired, shear‐induced floc damage and contamination of the plasmid liquor with genomic DNA and cell debris occurred, but plasmid DNA recovery was improved. Introduction of hydrophobic low‐density microspheres into the floc dramatically improved floc stiffness, phase separation and flotation efficiency, and reduced the solids content in the plasmid liquor 10‐fold. However, strong reinforcement of the cell debris lattice by these microspheres hindered plasmid release into the liquor beneath.

CONCLUSION: By incorporating magnetic or buoyant seeds during cell lysis we have identified new routes for separation of shear‐sensitive cell debris solids from crude plasmid‐containing liquors. Effective use of seeding approaches for difficult solid–liquid separation tasks will require evaluation of a wide range of seeds of varying architecture, size, shape, density and chemistry. Copyright © 2007 Society of Chemical Industry
Protective vaccination with hepatitis C virus NS3 but not core antigen in a novel mouse challenge model
Authors: El‐Gogo Susanne , Staib Caroline , Lasarte Juan José , Sutter Gerd , Adler Heiko
Published: December 2007

Background

Efficient vaccines against hepatitis C virus (HCV) infection are urgently needed. Vaccine development has been hampered by the lack of suitable small animal models to reliably test the protective capacity of immmunization.

Methods

We used recombinant murine gammaherpesvirus 68 (MHV‐68) as a novel challenge virus in mice and tested the efficacy of heterologous candidate human vaccines based on modified vaccinia virus Ankara or adenovirus, both delivering HCV non‐structural NS3 or core proteins.

Results

Recombinant MHV‐68 expressing NS3 (MHV‐68‐NS3) or core (MHV‐68‐core) were constructed and characterized in vitro and in vivo. Mice immunized with NS3‐specific vector vaccines and challenged with MHV‐68‐NS3 were infected but showed significantly reduced viral loads in the acute and latent phase of infection. NS3‐specific CD8+ T cells were amplified in immunized mice after challenge with MHV‐68‐NS3. By contrast, we did neither detect a reduction of viral load nor an induction of core‐specific CD8+ T cells after core‐specific immunization.

Conclusions

Our data suggest that the challenge system using recombinant MHV‐68 is a highly suitable model to test the immunogenicity and protective capacity of HCV candidate vaccine antigens. Using this system, we demonstrated the usefulness of NS3‐specific immunization. By contrast, our analysis rather discarded core as a vaccine antigen. Copyright © 2007 John Wiley & Sons, Ltd.
Suppression of immune responses to β‐lactoglobulin in mice by the oral administration of peptides representing dominant T cell epitopes
Authors: Mizumachi Koko , Tsuji Noriko M , Kurisaki Jun‐ichi
Published: December 2007

BACKGROUND: The significance of oral tolerance in the treatment of adverse immune reactions such as allergic and autoimmune diseases has been noted. In the present study, peptides that could effectively induce oral tolerance to bovine β‐lactoglobulin (BLG), a milk allergen, were investigated in a murine model.

RESULTS: The oral administration of peptides corresponding to the T cell epitope regions of BLG, i.e. p42–56, p62–76 and p139–154, apparently down‐regulated T cell proliferation to BLG. The in vitro cytokine production by the lymph node cells from the peptide‐fed mice cultured in the presence of the antigen was also analysed. It was found that p62–76 and p139–154 feeding suppressed the production of both Th1 and Th2 types. Interestingly, p139–154 feeding suppressed both T cell and antibody responses to BLG. Additionally, p139–154 feeding diminished BLG‐specific IgE and IgG1 antibody responses.

CONCLUSION: The unique tolerogen peptide p139–154 that could suppress both T and B cell responses to BLG in a murine model was identified. These findings can be useful for the selection of an optimum tolerogenic peptide to prevent and treat milk and other food allergies. Copyright © 2007 Society of Chemical Industry
Comparison of in vitro starch digestibility methods for predicting the glycaemic index of grain foods
Authors: Germaine Kirsty A , Samman Samir , Fryirs Catherine G , Griffiths Patricia J , Johnson Stuart K , Quail Kenneth J
Published: December 2007

BACKGROUND: In vitro starch digestibility tests are useful for the prediction of glycaemic index (GI). However, there are no internationally recognised methods and no one method has been found to be suitable for all food types. This study compared six in vitro methods, using four grain foods, including those with a varied particle size and soluble fibre content. Method variations included using chewing or mincing, mincing with or without amylase and incubation in a restricted versus non‐restricted system. Hydrolysis index (HI) values, calculated from the starch digestibility curves and GI prediction equations were used to compare the in vitro results to GI.

RESULTS: HI values for five of the six methods ranked all foods in the same order as the GI values. Using a GI prediction equation (predicted GIHI) the mincing (without amylase) non‐restricted method had the smallest standard error of prediction between the predicted GIHI and GI values. This method was then validated using 14 grain foods and demonstrated a significant correlation (r = 0.93, P < 0.01) between the in vitro starch digestibility and reported GI responses.

CONCLUSIONS: The non‐restricted mincing method showed good potential as a new in vitro starch digestibility method for predicting GI in grain foods. Copyright © 2007 Society of Chemical Industry