bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and evaluation of poly(L‐lactide‐co‐glycolide) (PLGA) microbubbles as a contrast agent for myocardial contrast echocardiography
Authors: Cui Wenjin , Bei Jianzhong , Wang Shenguo , Zhi Guang , Zhao Yuying , Zhou Xiaoshu , Zhang Hanwei , Xu Yong 
Published: January 2005

AbstractA kind of absorbable PLGA microbubble‐based contrast agent (PLGA microspheres with porous or hollow inner structure) was fabricated by an improved double emulsion‐solvent evaporation method. The contrast efficiency was evaluated and proved both in vitro and in vivo. By adjusting the polymer concentration and volume of the inner aqueous phase during the fabrication of microbubbles, the inner structure of the microbubbles could be controlled. Both air‐filled and perfluoropropane‐filled microbubbles can opacify the left ventricle. However, when compared with air‐filled microbubbles, perfluoropropane‐filled microbubbles can produce significantly longer enhancement in left ventricle in the dog model due to the lower diffusivity and lower solubility of perfluoropropane in blood. A suspension of perfluoropropane‐filled PLGA microbubbles (1.8 μm average microbubbles size, 2 × 108 microbubbles/mL concentration) has successfully and safely achieved myocardial opacification in closed‐chest dogs. A perfusion defect was observed in both of the two dogs with acute myocardial infarction with Power Contrast Imaging (PCI) triggered technology. In the examination of contrast in both ventricular and myocardial opacification, the high mechanical index (MI) was found to have superior contrast sensitivity over the low MI for PLGA‐based contrast agents. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 73B: 171–178, 2005
Quartz‐crystal microbalance‐dissipation technique for the study of initial adsorption of fibronectin onto tresyl chloride‐activated titanium
Authors: Hayakawa T. , Yoshinari M. , Nemoto K. 
Published: January 2005

AbstractThe immobilization of cell‐adhesive proteins onto titanium implants improves biological response at the implant–tissue interface. Previous studies demonstrated the easy and direct attachment of fibronectin onto titanium with the use of a 2,2,2‐trifluoroethanesulfonyl chloride (tresyl chloride) activation technique. The present study investigated the initial adsorption behavior of fibronectin on tresyl chloride‐activated titanium by the quartz‐crystal microbalance‐dissipation (QCM‐D) technique. The crystal resonant frequency and the dissipation shift of the oscillator were simultaneously measured by the injection of fibronectin/phosphate‐buffered saline solution (pH = 7.4). The tresyl chloride‐activated titanium surface showed a faster and greater decrease in frequency than that of untreated titanium, indicating that a greater amount of fibronectin was adsorbed in the former case during a 120‐min adsorption. The dissipation‐frequency plots revealed that, during the initial stage of adsorption, the bond between fibronectin and tresyl chloride‐activated titanium is stronger than that between fibronectin and untreated titanium. The QCM‐D technique can provide new insights into the adsorption mechanism of fibronectin. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater
Gentamicin‐loaded calcium carbonate materials: Comparison of two drug‐loading modes
Authors: Lucas‐Girot Anita , Verdier Marie‐Clémence , Tribut Olivier , Sangleboeuf Jean‐Christophe , Allain Hervé , Oudadesse Hassane 
Published: January 2005

AbstractSynthetic aragonite‐based porous materials were drug loaded with gentamicin sulphate, an antibiotic active on Staphylococcus aureus responsible for osteomyelitis. Drug loading was accomplished by two different ways: by integration of gentamicin in material during processing or by soaking material into gentamicin solutions. We first investigated the influence of drug loading on compressive strength of materials. Results indicate that soaked materials presented the same compressive strength than unloaded materials with the same porosity. By contrast, the integration of gentamicin during processing increased significantly the compressive strength of materials. The materials drug content before elution was a least 10 times higher when gentamicin was integrated during processing comparatively to soaked materials. The study of in vitro gentamicin release showed that for materials with gentamicin integrated during material processing, high concentrations of gentamicin were released up to 8 or 12 days, against 4 days for soaked materials. The transport coefficients calculation, for the first step of release, indicated that the rate of release was higher for materials with integrated gentamicin because of the higher gentamicin content. The porosity rate influenced the rate of release for materials positively with gentamicin integrated during processing contrary to soaked materials for which a higher porosity rate allowed a deeper penetration of gentamicin during drug loading and then a slightly slower release. Results indicate that aragonite‐based material with gentamicin integrated during material processing may be used either as resorbable device for release of high concentrations of gentamicin or as biomaterial for combined therapy: bone substitution and prevention or treatment of osteomyelitis. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 73B: 164–170, 2005
Nanoleakage within the hybrid layer: A correlative FEISEM/TEM investigation
Authors: Suppa Pietro , Breschi Lorenzo , Ruggeri Alessandra , Mazzotti Giovanni , Prati Carlo , Chersoni Stefano , Di Lenarda Roberto , Pashley David H. , Tay Franklin R. 
Published: January 2005

AbstractThe aim of this study was to compare the nanoleakage patterns of the resin–dentin interfaces of three dentin bonding systems at both TEM and field emission in lens SEM (FEI‐SEM) levels. A standardized smear layer was created with 180‐grit silicon carbide paper (SiC) on dentin disks obtained from 18 noncarious human third molars. Specimens were randomly divided into three groups and bonded with a two‐step total etching adhesive (Single Bond, SB), a two‐step, self‐etching adhesive (Clearfil SE BOND, SEB), and a one‐step, self‐etching adhesive (XENO III, XEIII). Nanoleakage was evaluated by using an ammoniacal silver‐nitrate solution. Specimens were processed for TEM and FEI‐SEM observation. The TEM of SB revealed silver deposits in adhesive and hybrid layers (HL). High‐magnification FEI‐SEM micrographs clearly identified these deposits as spherical clusters mainly associated with nonembedded collagen fibrils. TEM and FEI‐SEM examination of SEB revealed some clusters of silver deposits within porosities and small channels of the HL. Additional silver deposits were observed between the peritubular dentin walls and the resin tags. XEIII revealed very fine and diffuse silver grains throughout the entire HL. SEM visualization of nanoleakage at a high level of resolution has not been previously described. FEI‐SEM technology supported the TEM visualization with three‐dimensional morphological data of the relations between the HL constituents and nanoleakage. The results of the present study confirm the hypothesis that both total‐ and self‐etch adhesives are not able to fully infiltrate the dentin substrate. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 73B: 7–14, 2005
Distribution of sympathetic tissue plasminogen activator (tPA) to a distant microvasculature
Authors: O'Rourke James , Jiang Xi , Hao Zhifang , Cone Robert E. , Hand Arthur R. 
Published: January 2005

AbstractTissue plasminogen activator (tPA) is the predominant plasminogen activator present in the vascular and nervous systems. Prior studies of the two have emphasized different tPA sources; respectively, endothelium and neurons. A closer relationship is now suggested by evidence that the peripheral sympathetic nervous system synthesizes and infuses enzymatically active tPA into small artery walls and the microcirculation. TPA may thus be the only known neural product able to effect degradation of the artery wall extracellular matrix. This brief review considers historical and current indications for the existence of such an autonomically controlled system and some physiologic implications. Immunohistochemical tPA expression in small arteries and arterioles is more prominent in the outer wall sympathetic axon plexus than in endothelium. Its presence in nerve filaments beneath the seldom‐studied adventitia was obscured in earlier localizations. The systemic impact of a neural distribution is suggested by a 60% reduction of blood tPA activity after chemical sympathectomy. TPA‐bearing axons extend outward from ganglion neuron cell bodies to reach even thin‐walled vasa vasora and uveal microvessels. Ganglion cell bodies synthesize and package tPA in vesicles for the long axoplasmic transport. Densely innervated intact vessels release much greater amounts of tPA in vitro than do larger vessels, indicating a high neuron tPA production capacity and a large storage reservoir available within axon networks. The influence of an autonomically controlled plasmin production within small artery walls on regulation of blood pressure and capillary perfusion awaits further investigation. Its possible role in the pathogenesis of vessel wall matrix degradations in aging, hypertension, and diabetes may also merit further consideration. © 2005 Wiley‐Liss, Inc.
Influence of LIF and BMP‐2 on differentiation and development of glial cells in primary cultures of embryonic rat cerebral hemisphere
Authors: Adachi Tatsumi , Takanaga Hiromi , Kunimoto Manabu , Asou Hiroaki 
Published: January 2005

AbstractCells prepared from the cerebral hemisphere of embryonic Day 18 rats were maintained for 2 days in serum‐free modified Bottenstein‐Sato (mBS) medium containing thyroid hormone (TH), with or without leukemia inhibitory factor (LIF) or bone morphogenetic protein (BMP)‐2, and these influences on the differentiation and development of glial cells were investigated using the cells maintained in mBS medium containing TH as controls. The levels of glial fibrillary acidic protein (GFAP) expression and the number of GFAP‐positive astrocytes increased markedly with the addition of LIF or BMP‐2, and were enhanced further with the addition of both LIF and BMP‐2. The number of O1‐positive oligodendrocytes increased with the addition of LIF, whereas it decreased with the addition of BMP‐2. The number did not change with the addition of both cytokines. Using antibody against platelet‐derived growth factor (PDGF), we then excluded indirect effects of these cytokines through PDGF, which would increase by accelerated astrocyte development. When PDGF was neutralized, the number of oligodendrocytes increased under all conditions examined. As a result of the neutralization, the effect of BMP‐2 on oligodendrocyte differentiation was eliminated, although LIF remained effective. These results suggest that the differentiation of oligodendrocytes was delayed partially by PDGF even in control cultures. It is also suggested that LIF and BMP‐2, each of which accelerates the differentiation and development of astrocytes, would seem to have different effects on oligodendrocyte differentiation, i.e., LIF would directly affect oligodendrocyte differentiation, whereas BMP‐2 would affect it mainly through PDGF. © 2005 Wiley‐Liss, Inc.
Developmental profile of ErbB receptors in murine central nervous system: Implications for functional interactions
Authors: Fox Irina J. , Kornblum Harley I. 
Published: January 2005

AbstractThe ErbB family, ErbB1 (also known as the epidermal growth factor receptor EGFR), ErbB2, ErbB3, and ErbB4 comprise a group of receptor tyrosine kinases that interact with ligands from the epidermal growth factor (EGF) superfamily, subsequently dimerize, catalytically activate each other by cross‐phosphorylation, and then stimulate various signaling pathways. To gain a better understanding of in vivo functions of ErbB receptors in the central nervous system, the current study examined their mRNA expression throughout development in the mouse brain via in situ hybridization. EGFR, ErbB2, and ErbB4 exhibited distinct but sometimes overlapping distributions in multiple cell types within germinal zones, cortex, striatum, and hippocampus in prenatal and postnatal development. In addition, a subpopulation of cells positive for ErbB4 mRNA in postnatal cortex and striatum coexpressed mRNA for either EGFR or GAD67, a marker for γ‐aminobutyric acid (GABA)ergic interneurons, suggesting that both ErbB4 and EGFR are coexpressed in GABAergic interneurons. In contrast, ErbB3 mRNA was not detected within the brain during development and only appeared in white matter tracts in adulthood. Together, these findings suggest that ErbB receptors might mediate multiple functions in central nervous system development, some of which may be initiated by EGFR/ErbB4 heterodimers in vivo. © 2005 Wiley‐Liss, Inc.
Optical Spectra of Unfolded Proteins: A Partially Ordered Polymer Problem
Authors: Keiderling Timothy A. , Xu Qi 
Published: January 2005

AbstractProteins are hetero‐sequence polypeptides with complex folded structures whose topology and structural details are vital to their biological function. In this paper, uses of electronic circular dichroism (ECD) in the uv, infrared (IR) absorption and its chiroptical variant, vibrational circular dichroism (VCD) for study of residual structure in peptide models and unfolded proteins under various conditions are addressed. The complementary information gained from analysis of the short range vibrational coupling (with IR and VCD) vs. long range dipole coupling (from ECD) allow detection of partial ordering. The vibrational techniques show an ability to detect local order often missed by ECD (or fluorescence). Perturbation with thermal and solvent variation can then probe stabilities. Furthermore the rapid timescales allow such spectra to follow dynamic changes. Examples from protein folding of cytochrome c and various beta containing proteins are given.
Infrared Spectroscopy and X‐Ray Diffraction Studies on the Structure and Thermal Behavior of Biodegradable Polyhydroxyalkanoates
Authors: Sato Harumi , Padermshoke Adchara , Nakamura Masayuki , Murakami Rumi , Hirose Fuminobu , Senda Kenichi , Terauchi Hikaru , Ekgasit Sanong , Noda Isao , Ozaki Yukihiro 
Published: January 2005

AbstractThe structure and thermal behavior of new types of bacterial copolyester, poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate); P(HB‐co‐HHx) (HHx=2.5, 3.4, and 12 mol %) have been explored by means of wide‐angle x‐ray diffraction (WAXD), differential scanning calorimetry (DSC), and infrared (IR) spectroscopy. The WAXD pattern of P(HB‐co‐HHx) (HHx=12 mol %) copolymer measured at room temperature has revealed that it has an orthorhombic system (α=β=γ=90°) with a=5.76Å, b=13.20Å, c=5.96Å (fiber repeat), which is identical to that of poly(3‐hydroxybutyrate) (PHB). It has been found from the temperature‐dependent variations of the WAXD pattern that only the a lattice parameter shows the thermal expansion, while the b lattice parameter changes little with temperature in the crystalline P(HB‐co‐HHx) (HHx=12 mol %). This observation suggests that there are inter and intramolecular interactions between C=O groups and alkyl groups along the a axis and that interactions are broken little by little with temperature. IR spectra were measured for the four kinds of polymers over a temperature range from 30°C to high temperatures (200°C; PHB, 180°C; P(HB‐co‐HHx) (HHx=2.5 mol %), 180°C; P(HB‐co‐HHx) (HHx=3.4 mol %), 150°C; P(HB‐co‐HHx) (HHx=12 mol %)). Temperature‐dependent IR spectral variations were analyzed for the CH, C=O, and C‐O‐C stretching band regions, and bands characteristic of crystalline and amorphous parts were identified in each region. It has been found from the IR study that the strength of interaction between the C=O group and the CH3 (or CH2) group is similar among the four polymers and that the population of C=O groups that are not involved in the interaction becomes higher with the increase in HHx. Both WAXD and IR studies have revealed that the crystallinity of P(HB‐co‐HHx) (HHx=12 mol %) decreases gradually starting from relatively low temperature (about 60°C) while that of PHB remains high up to 170°C.
Theory of Intrachain Relaxation Spectra for Polymer Networks Possessing a Short‐ or Long‐Scale Ordering. Effects of the Nematic Ordering on the Relaxation Spectrum of a Polymer Network with Included Rods
Authors: Toshchevikov Vladimir P. , Gotlib Yuli Ya. , Torchinskii Isaak A. , Shevelev Vladimir A. 
Published: January 2005

AbstractWe discuss the relaxation properties of polymer networks possessing either short‐scale ordering caused by rigidity of network strands or long‐scale liquid crystalline order. The main topics of the paper are the equilibrium and local dynamic properties of a polymer network ordered due to nematic‐like interactions of the network segments with included rod‐like particles. A simplified three chain network model is used. Lagrange multipliers in the equations of motion of hard rods are replaced by their averaged values. This approximation corresponds to modelling the rod‐like particles by elastic Gaussian springs, their mean‐square lengths independent of the ordering. Nematic‐like interactions between network segments and rods are taken into account in terms of the Maier‐Saupe mean‐field approximation. Nematic ordering of rods induces ordering of the network segments. Relaxation spectrum of the ordered network splits into two main branches for the parallel and perpendicular components of the chain segments with respect to the director. We calculate the relaxation times of a polymer network as functions of the wave number. The relaxation spectrum of an isotropic network and that of the ordered network with included rods are compared.
NMR Spectroscopy and Atomic Force Microscopy Characterization of Hybrid Organic – Inorganic Coatings
Authors: Brus Jiří , Špírková Milena 
Published: January 2005

AbstractHybrid organic–inorganic (O‐I) epoxide‐based products made from functionalized organosilicon precursors, oligomeric di‐ and triamines and in some cases colloidal silica particles were characterized by NMR spectroscopy and atomic force microscopy (AFM). The kinetics and reaction mechanism of condensation reactions, structure and segmental dynamics of final films, as well as homogeneity and partial ordering were studied by solid‐state NMR spectroscopy (2D CRAMPS, 2D 1H‐13C WISE, relaxation experiments); the surface morphology and other surface characteristics were determined by AFM.
Schiff bases of gossypol: an NMR and DFT study
Authors: That Quang Ton , Nguyen Kim Phi Phung , Hansen Poul Erik 
Published: January 2005

AbstractSchiff bases of gossypol with benzylamine, methylamine, 4‐aminoacetophenone and 4‐fluoroaniline have been synthesized and characterized by NMR spectroscopy. All the Schiff bases of gossypol are in the enamine form according to 3J(HC,NH) and 1J(N,H) coupling constants. The spectra are basically unchanged by change of solvent (CD2Cl2, THF‐d8 and CD3OD) and by variation of temperature. For the derivative of benzylamine, deuterium isotope effects on 13C chemical shifts are determined. They support strongly the enamine form and serve as a reference for other tautomeric Schiff bases. Structures and NMR nuclear shieldings of model compounds (the second monomer is replaced by a 2‐hydroxybenzene ring) have been calculated by density functional theory (DFT) methods. A good correlation is observed between calculated 13C nuclear shieldings of the enamine form and observed 13C chemical shifts. Copyright © 2005 John Wiley & Sons, Ltd.
NMR investigation into the dynamic behaviour of a novel C2‐symmetric macrocyclic ligand
Authors: Scheuermann J. Erik W. , Bento Edson S. , Hawkes Geoffrey E. , Watkinson Michael 
Published: January 2005

AbstractThe variable‐temperature 1H NMR spectra of a tosylated triazacyclononane are reported. The spectra show a dynamic process which is assigned to hindered rotation about the amide‐like NS bonds, and a value for the free energy of activation for the rotations is derived, ΔG* = 50.2 kJ mol−1 at 273 K. Steric and electronic factors which influence the barrier are discussed. Copyright © 2005 John Wiley & Sons, Ltd.
Analysis and calculation of the 31P and 19F NMR spectra of hexafluorocyclotriphosphazene
Authors: Kapička Libor , Dastych Dalibor , Richterová Valerie , Alberti Milan , Kubáček Pavel 
Published: January 2005

AbstractThe higher order high‐resolution 31P and 19F NMR spectra of hexafluorocyclotriphosphazene (F2PN)3 were measured at 183 K and interpreted using subspectral analysis and iterative fitting computation. (F2PN)3 forms a rigid nine‐spin system [A[X]2]3 with D3h symmetry. Two complete and very similar sets of six experimental spin–spin coupling constants, 1J(P,F), 2J(P,P), 2J(F,F), 3J(P,F), 4J(F,F)cis and 4J(F,F)trans, were determined for the first time. Theoretical DFT calculations of chemical shifts and coupling constants were performed to assess their predictive value. The PP/aug‐cc‐pVDZ treatment rendered the best agreement with experimental data. Copyright © 2005 John Wiley & Sons, Ltd.
A new dihydroflavonol from Pinus sylvestris L.
Authors: Sinkkonen Jari , Liimatainen Jaana , Karonen Maarit , Pihlaja Kalevi 
Published: January 2005

AbstractA novel dihydroflavonol, C‐6,O‐7‐dimethylaromadendrin, was isolated from a 70% aqueous acetone extract of pine (Pinus sylvestris L.) bark. Its structure was determined by high‐resolution negative fast atom bombardment mass spectrometry and NMR spectroscopy. The complete assignment of proton and carbon signals was achieved by 2D NMR experiments: HSQC, HMBC, DQF‐COSY and NOESY. Copyright © 2005 John Wiley & Sons, Ltd.
Transmit and receive transmission line arrays for 7 Tesla parallel imaging
Authors: Adriany Gregor , Van de Moortele Pierre‐Francois , Wiesinger Florian , Moeller Steen , Strupp John P. , Andersen Peter , Snyder Carl , Zhang Xiaoliang , Chen Wei , Pruessmann Klaas P. , Boesiger Peter , Vaughan Tommy , Uğurbil Kāmil 
Published: January 2005

AbstractTransceive array coils, capable of RF transmission and independent signal reception, were developed for parallel, 1H imaging applications in the human head at 7 T (300 MHz). The coils combine the advantages of high‐frequency properties of transmission lines with classic MR coil design. Because of the short wavelength at the 1H frequency at 300 MHz, these coils were straightforward to build and decouple. The sensitivity profiles of individual coils were highly asymmetric, as expected at this high frequency; however, the summed images from all coils were relatively uniform over the whole brain. Data were obtained with four‐ and eight‐channel transceive arrays built using a loop configuration and compared to arrays built from straight stripline transmission lines. With both the four‐ and the eight‐channel arrays, parallel imaging with sensitivity encoding with high reduction numbers was feasible at 7 T in the human head. A one‐dimensional reduction factor of 4 was robustly achieved with an average g value of 1.25 with the eight‐channel transmit/receive coils. Magn Reson Med 53:434–445, 2005. © 2005 Wiley‐Liss, Inc.