bluuebunny/crossref_metadata_2025_split huggingface dataset:
Direct correlation between adsorption‐induced changes in protein structure and platelet adhesion
Authors: Hylton Donna M. , Shalaby Shalaby W. , Latour Robert A. 
Published: April 2005

AbstractIt is widely recognized that adsorbed proteins on biomaterial surfaces tend to initiate thrombus formation, although the specific mechanisms involved are still not well understood. In attempts to decrease the conformational change of adsorbed proteins, surface treatments that reduce surface hydrophobicity have been considered, such as the sulfonation of low‐density polyethylene and isotactic polypropylene. The objectives of this present research were to study how changes in surface chemistry influence the degree of conformational change of adsorbing proteins and to investigate the correlation between the change in adsorbed protein structure and platelet response. Adsorbed porcine serum albumin and porcine fibrinogen were used as the model proteins for determining the effects of sulfonation on protein conformational change. Circular dichroism spectroscopy studies showed that the proteins were less altered structurally on the sulfonated surfaces. Platelet adhesion studies were used to correlate the number of adhered platelets with the amount of conformational change in adsorbed proteins on the polymer surface. The results of these studies show a linear correlation between platelet adhesion and the degree of adsorption‐induced protein conformational change. These findings suggest that the degree of protein conformational change after adsorption is a dominant mechanism governing platelet interactions with biomaterial surfaces. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res 73A: 349–358, 2005
The viability and function of primary rat hepatocytes cultured on polymeric membranes developed for hybrid artificial liver devices
Authors: Grant M. Helen , Morgan Caroline , Henderson Catherine , Malsch Günther , Seifert Barbara , Albrecht Wolfgang , Groth Thomas 
Published: April 2005

AbstractBioartificial liver devices require membranes to support the function and viability of hepatocytes because they are anchorage‐dependent cells. This study investigated the ability of several polymeric membranes to support the functions of primary hepatocyte cultures. Tailor‐made membranes were sought by synthesizing acrylonitrile copolymers with different comonomers resulting in ionic, hydrophilic, or reactive functional groups on the polymer surface. Hepatocyte morphology and viability were assessed by confocal microscopy, and function by the content and activities of cytochrome P450, and the expression of glutathione S‐transferases. Hydrophilic membranes (polyacrylonitrile and acrylonitrile copolymerized with 2‐acrylamino‐2‐methyl‐propane sulfonic acid) were more biocompatible than hydrophobic membranes such as polysulfone. The chemistry of the hydrophilic group was important; amine groups had a deleterious effect on maintenance of the primary hepatocytes. The biocompatibility of hydrophobic membranes was improved by collagen coating. Improving the chemistry of membranes for artificial liver devices will enhance the phenotypic stability of the cells, enabling us to prolong treatment times for patients. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res 73A: 367–375, 2005
Importance of accurate charges in molecular docking: Quantum mechanical/molecular mechanical (QM/MM) approach
Authors: Cho Art E. , Guallar Victor , Berne Bruce J. , Friesner Richard 
Published: April 2005

AbstractThe extent to which accuracy of electric charges plays a role in protein‐ligand docking is investigated through development of a docking algorithm, which incorporates quantum mechanical/molecular mechanical (QM/MM) calculations. In this algorithm, fixed charges of ligands obtained from force field parameterization are replaced by QM/MM calculations in the protein environment, treating only the ligands as the quantum region. The algorithm is tested on a set of 40 cocrystallized structures taken from the Protein Data Bank (PDB) and provides strong evidence that use of nonfixed charges is important. An algorithm, dubbed “Survival of the Fittest” (SOF) algorithm, is implemented to incorporate QM/MM charge calculations without any prior knowledge of native structures of the complexes. Using an iterative protocol, this algorithm is able in many cases to converge to a nativelike structure in systems where redocking of the ligand using a standard fixed charge force field exhibits nontrivial errors. The results demonstrate that polarization effects can play a significant role in determining the structures of protein‐ligand complexes, and provide a promising start towards the development of more accurate docking methods for lead optimization applications. © 2005 Wiley Periodicals, Inc. J Comput Chem 26: 915–931, 2005
Measuring human cardiac tissue sodium concentrations using surface coils, adiabatic excitation, and twisted projection imaging with minimal T2 losses
Authors: Ouwerkerk Ronald , Weiss Robert G. , Bottomley Paul A. 
Published: April 2005

AbstractPurposeTo measure tissue sodium concentrations in the human heart with 23Na MRI using a surface coil, thereby eliminating the effects of inhomogeneous excitation by surface coils and minimizing T1 and T2 relaxation.Materials and MethodsWe combined fully relaxed, very short‐echo, 23Na twisted projection imaging (TPI) with adiabatic half passage (AHP) excitation and external referencing on subjects and comparing with a concentration reference phantom scan to quantify TSC with surface coils. 23Na signal losses during hard (square), composite, and tanh/tan amplitude/frequency‐modulated AHP excitation pulses were analyzed over a wide range of RF field strengths and T2short values.ResultsAHP excitation yielded a homogeneous excitation flip angle and negligible losses compared to a 90° hard pulse wherever the B1 field exceeded the adiabatic threshold, rendering this sequence suitable for applications that use surface coil excitation. An AHP 23Na TPI sequence was used with a surface coil at 1.5 T to noninvasively quantify myocardial TSC in 10 normal volunteers. The mean TSC was 43 ± 4, 53 ± 12, and 17 ± 4 μmol/g in the left ventricular (LV) free wall, septum, and adipose tissue, respectively, consistent with prior invasive measurements on biopsy and autopsy specimens.ConclusionIt is now possible to noninvasively quantify TSC in the human heart with surface coil 23Na MRI. J. Magn. Reson. Imaging 2005;21:546–555. © 2005 Wiley‐Liss, Inc.
Effect of inversion time on delayed‐enhancement magnetic resonance imaging with and without phase‐sensitive reconstruction
Authors: Setser Randolph M. , Chung Yiu Cho , Weaver Joan A. , Stillman Arthur E. , Simonetti Orlando P. , White Richard D. 
Published: April 2005

AbstractPurposeTo evaluate the consistency and inversion time (TI) independence of phase‐sensitive reconstruction (PSIR) delayed‐enhancement (DE) MRI in a clinical setting.Materials and MethodsMid‐ventricular short‐axis DE images were acquired in 25 patients using three TIs: 1) optimized to null viable myocardium, 2) 50 msec less than optimal TI, and 3) 50 msec greater than optimal TI. At each TI, images were acquired with PSIR and without magIR. In each image, percent scar was computed as the ratio of nonviable to total pixels in the left ventricle (LV).ResultsIn the magIR images, percent scar was 23% ± 15% (optimal), 11% ± 11% (short), and 22% ± 15% (long). In PSIR images, percent scar was 25% ± 15% (optimal), 22% ± 15% (short), and 22% ± 14% (long). Percent scar was significantly underestimated in magIR images with short TI, but no statistically significant difference in percent scar was observed at the optimal or long TIs.ConclusionDE‐MRI is a robust imaging technique for clinical use. PSIR provided consistent image quality independently of TI, at least over the range of TIs evaluated in this study. However, neither image quality nor scar appearance in the PSIR images was significantly different from that in the magIR images when TI was at or above the null point of viable myocardium. J. Magn. Reson. Imaging 2005;21:650–655. © 2005 Wiley‐Liss, Inc.
Recombinant protein‐based ELISA and immuno‐cytochemical assay for the diagnosis of SARS
Authors: Carattoli Alessandra , Bonito Paola Di , Grasso Felicia , Giorgi Colomba , Blasi Francesco , Niedrig Matthias , Cassone Antonio 
Published: April 2005

AbstractA new Coronavirus (SARS‐CoV) is the aetiological agent of the severe acute respiratory syndrome (SARS). Because of the critical role played by serological assays for SARS diagnosis, an in‐house ELISA based on SARS‐CoV recombinant antigens was developed. The SARS‐CoV nucleocapsid protein (N), three N fragments (N1, N2, and N3) and the intraviral domain of the membrane protein (M2) were cloned and expressed in Escherichia coli as histidine‐tagged proteins. Six reference sera from SARS patients were used to detect virus‐specific IgG in an ELISA using each recombinant protein as coating antigen. High‐titre positive reactions were detected in all SARS positive sera. The specificity of the assay appears to be high as no positive reaction was detected in the sera of 20 healthy subjects and 73 patients with non‐SARS, low‐tract respiratory infections. Specific hyper‐immune sera to SARS‐CoV and the recombinant proteins, N, N1, N2, N3, and M2 were also generated in mice and rabbits. The specificity of these sera was confirmed by an immunocytochemical assay on biochips of SARS‐CoV infected and uninfected cells. J. Med. Virol. 76:137–142, 2005. © 2005 Wiley‐Liss, Inc.
Oligonucleotide array for simultaneous detection of respiratory viruses using a reverse‐line blot hybridization assay
Authors: Coiras M.T. , López‐Huertas M.R. , López‐Campos G. , Aguilar J.C. , Pérez‐Breña P. 
Published: April 2005

AbstractThe interest in developing new diagnostic methods based on arrays of multiple probes to detect and type simultaneously a wide range of different infectious agents is increasing. This becomes a necessity in the case of infectious agents such as respiratory viruses that cause diseases with very similar signs and symptoms. Such tools will permit rapid and accurate diagnosis of different agents causing respiratory infection leading to the most adequate prevention and/or treatment measures. In this article a reverse‐line blot hybridization (RLB) assay for the detection of a wide range of respiratory viruses is presented and evaluated for its usefulness in routine diagnosis. This assay employs an array of 18 oligonucleotide probes immobilized on a nylon membrane. Biotin‐labeled PCR products obtained with two multiplex reverse transcription (RT)‐polymerase chain reaction (PCR) assays described previously, which allow for the detection of fourteen different groups of respiratory viruses, were hybridized to the oligonucleotide array. Detection was performed using a chemiluminescent method. The standardization of the method showed that the RLB assay could be an alternative to the nested PCR assay for enhancing the sensitivity in the detection of the amplified products, avoiding the problem of cross‐over contamination, increasing the specificity, and therefore simplifying the method. This is of main interest in laboratories with few facilities. The feasibility and accuracy of the RT‐PCR‐RLB assay for detecting respiratory viruses proves that such approach could be a first stage to develop a microarray assay for routine diagnosis of infectious diseases. J. Med. Virol. 76:256–264, 2005. © 2005 Wiley‐Liss, Inc.
Non‐planar heme deformations and excited state displacements in horseradish peroxidase detected by Raman spectroscopy at Soret excitation
Authors: Huang Qing , Schweitzer‐Stenner Reinhard 
Published: April 2005

AbstractWe studied the out‐of‐plane modes of horseradish peroxidase (HRP) in different spin, oxidation and ligation states by measuring the respective resonance Raman spectra with (near) Soret excitation. The non‐planar modes of the heme are Raman inactive for planar macrocycles, but become resonance Raman active in the presence of out‐of‐plane deformations. The thus induced Raman scattering results mostly from Franck–Condon type coupling. We observed bands from a variety of out‐of‐plane modes such as γ5, γ6, γ7(A2u) modes, γ21 and γ22(Eg), γ15(B2u) and γ11(B1u). The appearance of these bands is clearly indicative of non‐planar deformations of the same symmetry. We determined the relative intensities of all sufficiently intense Raman modes of ferric pentacoordinated, quantum mixed and hexacoordinated low‐spin as well as of ferrous pentacoordinated high‐spin HRP C. The apparent vibronic coupling parameters were obtained from a self‐consistent analysis of the Raman intensities and the respective optical absorption spectrum. They revealed significantly reduced displacements of the excited B‐state for the ferrous, deoxy‐like state compared with the resting ferric state. An analysis of the obtained coupling strengths of out‐of‐plane modes revealed that they are predominantly induced by static non‐planar deformations along the normal coordinates of the lowest wavenumber modes of a given symmetry type. We used the deformations of the heme in resting HRP C to determine the vibronic coupling strength of the experimentally detectable out‐of‐plane modes and subsequently employed this information to obtain the non‐planar deformations for the investigated ferric hexacoordinated low‐spin state. This yielded a substantial reduction of the ruffling distortion, whereas the doming deformation remained mostly unaffected by the change of the iron's spin and ligation state. Copyright © 2005 John Wiley & Sons, Ltd.
Temperature and Pressure Dependence of α‐Relaxation and Free Volume in Poly(vinyl acetate)
Authors: Dlubek Günter , Kilburn Duncan , Alam M. Ashraf 
Published: April 2005

AbstractSummary: We analysed reported specific volume V from pressure‐volume‐temperature (PVT) experiments for poly(vinyl acetate) (PVAc) using the Simha‐Somcynsky equation of state (S‐S eos) and calculated the specific occupied volume, Vocc, and hole free volume, Vfh We found that Vocc shows almost no thermal expansion but is distinctly compressible (T > Tg). Due to this, Vfh = V − Vocc is not a unique function of V but can depend on the specific values of P and T giving rise to the particular value for V. We observed that with decreasing temperature the α‐relaxation detected via dielectric measurements slows down faster than the shrinkage of hole free volume Vfh would predict on the basis of the free volume theory of Cohen and Turnbull. Vfh becomes zero at approximately 65 K below the Vogel temperature T0, $T'_0 = T_0 - 65\,{\rm K}$. Plots of the α‐relaxation frequency log ωα versus 1/Vfh can be linearised when taking into account this discrepancy by substituting 1/Vfh by 1/(Vfh − ΔV) with $\Delta V = E_{{\rm fh}} (T_0 - T'_0 )$, or by including an energy term of the type exp[−E′/R(T − T0)] in the pre‐exponential factor of the frequency‐volume equation. Our results indicate that the α‐relaxation in PVAc operates via the Cohen‐Turnbull mechanism only when liquid‐like clusters of cells of the S‐S lattice appear which contain a hole free volume of three or more empty S‐S cells. For regions with a smaller number of empty cells an activation energy is required for allowing segmental motion via the cooperative rearranging of cells. The β‐(Johari‐Goldstein) relaxation which is a non‐cooperative, more local, process follows completely the free volume theory. The same seems to be true for the primitive (uncoupled) relaxation of the coupling model.
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Temperature Dependence of Free Volume in Pure and Silica‐Filled Poly(dimethyl siloxane) from Positron Lifetime and PVT Experiments
Authors: Dlubek Günter , De Udayan , Pionteck Jürgen , Arutyunov Nikolai Yu. , Edelmann Matthias , Krause‐Rehberg Reinhard 
Published: April 2005

AbstractSummary:The microstructure of the free volume and its temperature dependence in two poly(dimethyl siloxane)s (PDMS), one in the pure state and the other filled with 35 wt.‐% of an in situ hydrophobized fumed silica with a specific surface area of 200–300 m2 · g−1, were studied by pressure‐volume‐temperature experiments (PVT, T = 22–156 °C, P = 10–200 MPa) and positron annihilation lifetime spectroscopy (PALS, T = −173–100 °C, P = 10−5 MPa). The Simha‐Somcynsky equation of state was used to estimate the hole free volume fraction, h, and free and occupied volumes, Vf = hV and Vocc = (1 − h)V, from the specific total volume, V. The PALS spectra were analyzed with the routine LT9.0, which allowed for a dispersion, σi, in all three of the lifetimes: the para‐positronium (p‐Ps, τ1), positron (e+, τ2), and ortho‐positronium (o‐Ps) lifetime (τ3). This kind of analysis delivered correct p‐Ps lifetime parameters, τ1, σ1, and I1. It was speculated that e+, like o‐Ps, undergoes Anderson localization at empty sites of the, static or dynamic, disordered structure. The hole size distribution, its mean value, 〈vh〉, and dispersion, σh, were calculated from the o‐Ps lifetimes. A comparison of 〈vh〉 with Vf was used to estimate the specific hole number, $N'_{\rm h}$. During melting of the semicrystalline samples at−38 °C (Tm), 〈vh〉 increased abruptly, and σh suddenly decreased. Both effects are explained by the disappearance of the rigid‐amorphous fraction (RAF) and, thus, a reduction in the dynamic heterogeneity. The following leveling‐off in 〈vh〉 and the low value of σh are attributed to the fast segmental relaxation in the PDMS melts which leads to a smearing of the molecule density distribution around a hole during the o‐Ps lifetime.
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Glutathione‐S‐transferase‐1 and interleukin‐1β gene polymorphisms in Japanese patients with Parkinson's disease
Authors: Nishimura Masataka , Kuno Sadako , Kaji Ryuji , Yasuno Katsuhito , Kawakami Hideshi 
Published: April 2005

AbstractWe studied genetic polymorphisms in the glutathione‐S‐transferase‐1 (GST‐1) gene region and the interleukin‐1β (IL‐1β) promoter region in patients with Parkinson's disease (PD, n = 361), as well as controls (n = 257). Although we have confirmed the previous results, in a larger sample, that the IL‐1β genotype has affected the age at onset of PD patients, no contribution of the GST‐1 gene polymorphism was observed in the allele frequency or the onset age of the disease in Japanese persons. © 2005 Movement Disorder Society
Synthesis of poly(vinyl chloride)‐b‐poly(2‐ethylhexyl acrylate)‐b‐poly(vinyl chloride) by the competitive single‐electron‐transfer/degenerative‐chain‐transfer mediated living radical polymerization of vinyl chloride initiated from α,ω‐di(iodo)poly(2‐ethylhexyl acrylate) and catalyzed with sodium dithionite in water
Authors: Percec Virgil , Popov Anatoliy V. , Ramirez‐Castillo Ernesto , Hinojosa‐Falcon Luis A. 
Published: April 2005

Abstractα,ω‐Di(iodo)poly(2‐ethylhexyl acrylate)s [α,ω‐di(iodo)P2EHAs] with number‐average molecular weights of 13,700 and 20,400 were synthesized by the single‐electron‐transfer/degenerative‐chain‐transfer mediated living radical polymerization (SET–DTLRP) of 2‐ethylhexyl acrylate initiated with iodoform and catalyzed by sodium dithionite in water at 23 and 30 °C. These α,ω‐di(iodo)P2EHAs were used as macroinitiators for the SET–DTLRP of vinyl chloride, which was carried out under similar reaction conditions to synthesize ABA block copolymers containing poly(vinyl chloride) in the A blocks and poly(2‐ethylhexyl acrylate) in the B block. Poly(vinyl chloride)‐b‐poly(2‐ethylhexyl acrylate)‐b‐poly(vinyl chloride) was synthesized with 100% initiator efficiency. This synthetic method provides for the first time access to a diversity of block copolymers and other complex architectures based on combinations of thermoplastic poly(vinyl chloride)and elastomeric polyacrylates. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2276–2280, 2005
New fluorinated thermoplastic elastomers. III. Novel method of synthesis and characterization of alternating fluorinated polyimide/fluorinated polyhybridsiloxane block copolymers via polycondensation
Authors: Andre S. , Guida‐Pietrasanta F. , Rousseau A. , Boutevin B. , Caporiccio G. 
Published: April 2005

AbstractThe synthesis of fluorinated polyimide/fluorinated polyhybridsiloxane (FPI–FPHSX) block copolymers was achieved through the polycondensation of α,ω‐dichlorosilane fluorinated polyimides and α,ω‐disilanol fluorinated polyhybridsiloxanes. Three FPI–FPHSX block copolymers with 41, 50, and 76 wt % polyimide were synthesized and characterized by the tuning of the number‐average molecular weight of the soft polyhybridsiloxane segments. The influence of the soft‐segment length on the behavior of the thermoplastic elastomer material was studied, including the surface tension and thermal properties. The thermomechanical properties of the FPI–FPHSX block copolymers were also examined. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2237–2247, 2005
Methods of preparation of novel composites of poly(ϵ‐caprolactone) and a modified Mg/Al hydrotalcite
Authors: Tammaro Loredana , Tortora Mariarosaria , Vittoria Vittoria , Costantino Umberto , Marmottini Fabio 
Published: April 2005

Abstract12‐Hydroxydodecanoate (HD) anions were intercalated, via an ion‐exchange procedure, onto a Mg/Al hydrotalcite‐like compound with the formula [Mg0.65Al0.35(OH)2](NO3)0.35·0.56H2O. The obtained intercalate, characterized by chemical and thermal analyses, X‐ray powder diffraction, and Fourier transform infrared spectroscopy, had the formula [Mg0.65Al0.35(OH)2](NO3)0.08(HD)0.28·0.56H2O and an interlayer distance of 2.27 nm. Structural considerations indicated that the charge‐balancing HO(CH2)11COO− anions were accommodated in the interlayer region as a monofilm of partially interdigitated alkyl chains in a trans planar conformation and bearing the alcoholic group. The organically modified hydrotalcite was used to prepare novel composites based on poly(ϵ‐caprolactone) (PCL) with different procedures: (1) solvent casting, (2) ring‐opening polymerization of ϵ‐caprolactone, and (3) blending of precursors consisting of a PCL intercalated oligomer with a high‐molecular‐weight PCL. Microcomposites were obtained by the solvent casting of a mixture of a high‐molecular‐weight PCL and the modified hydrotalcite. The ring‐opening polymerization of ϵ‐caprolactone initiated by the OH groups of the alkyl chains intercalated in the hydrotalcite led to hybrid materials in which a low‐molecular‐weight PCL was in part intercalated into the modified hydrotalcite. Nanocomposites containing exfoliated hydrotalcite were obtained through the mixing, in different weight ratios, of hybrids consisting of PCL oligomers and modified hydrotalcite with a commercial high‐molecular‐weight PCL. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2281–2290, 2005
Crystalline morphology evolution in PCL thin films
Authors: Qiao Congde , Zhao Junchai , Jiang Shichun , Ji Xiangling , An Lijia , Jiang Bingzheng 
Published: April 2005

AbstractThe transition of crystalline morphology is revealed in poly(ϵ‐caprolactone) (PCL) thin films as the polymer film thickness changes from hundreds of nanometers to several nanometers. The PCL can crystallize into spherulites, dense‐branching morphology (DBM), or dendrites, depending on the polymer film thickness. It was found that when the polymer film thickness approaches 2Rg (radius of gyration of polymer), there is a remarkable change in crystalline morphology. Under this condition, the polymer crystallization is a diffusion‐controlled process. When the value of polymer film thickness closes to Rg, PCL cannot crystallize, and a dewetting phenomenon will take place. Moreover, polymer morphology can be controlled by varying supercooling. The effect of molecular weight on polymer morphology has been investigated. The main factors that affected pattern formation in nonequilibrium crystallization are also discussed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1303–1309, 2005