bluuebunny/crossref_metadata_2025 huggingface dataset:
Neuronal generation, migration, and differentiation in the mouse hippocampal primoridium as revealed by enhanced green fluorescent protein gene transfer by means of in utero electroporation
Authors: Nakahira Eiko , Yuasa Shigeki
Published: January 2005

Neuronal migration defects in the hippocampus during development are thought to be involved in various mental disorders. Studies of neural cell migration in the developing cerebrum have focused mainly on the neocortex, but those that have been performed on the developing hippocampal formation have not been adequately carried out. In the present study, the morphological differentiation of immature neurons that form the laminar structure of the hippocampus was investigated by labeling ventricular surface cells with the expression vector of the enhanced‐green‐fluorescent‐protein (EGFP) gene. Vector DNA was transfected into spatially and temporally restricted neuroepithelium of the hippocampal primordium by in utero electroporation, and the morphology of EGFP‐labeled migratory neurons and their interrelationships with the radial glial arrangement were observed. Pyramidal cells of Ammon's horn began to migrate radially along glial processes from a broad area of neuroepithelium on embryonic day (E)14. Large numbers of multipolar cells were found in the intermediate zone in the initial stage and stratified pyramidal cells appeared later. Dentate granule cells were labeled later than (E)16 and originated from a restricted area of neuroepithelium adjacent to the fimbria. Their initial migration was rapid and independent of radial glial fibers. Subsequent tangential migration in the subpial space and their ultimate settling into the forming dentate gyrus were closely associated with the radial glia. These findings indicate that distinct cellular mechanisms are involved in the development of the cortical layer of Ammon's horn and dentate gyrus. J. Comp. Neurol. 483:329–340, 2005. © 2005 Wiley‐Liss, Inc.
Preparation and Coordination Chemistry of n‐Allylaminophosphane
Authors: Slawin Alexandra M. Z. , Wheatley Joanne , Woollins J. Derek
Published: January 2005

Reaction of allylamine with 1 equiv. of Ph2PCl in the presence of NEt3, proceeds in THF to give (allylamino)phosphane 1. 1 has been coordinated as a monodentate P ligand with Au, Pd, Pt, Ru, Rh, Ir and as a bidentate P,allyl ligand to Pt. Reaction of KOtBu with [PtCl2{Ph2PNH(C3H5)}2] in methanol gives [Pt{Ph2PNH(C3H8O)}2]. The X‐ray structures of 1.Se and four demonstrative monodentate complexes all reveal intramolecular N–H···Cl hydrogen bonding. The structure of [Pt{Ph2PNH(C3H8O)}2] consists of an N–H···O hydrogen‐bonded dimer in the solid state. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
First Examples of β‐Diketonate Platinum(II) Complexes with Sulfoxide Ligands
Authors: De Pascali Sandra A. , Papadia Paride , Ciccarese Antonella , Pacifico Concetta , Fanizzi Francesco P.
Published: January 2005

New platinum(II) complexes have been prepared as models for explaining the coordination of multiple β‐diketonate li‐gands to give [Pt(O,O′‐acac)(γ‐acac)L] species. The new com‐pounds containing both an O,O′‐chelated acetylacetonate ligand and a sulfoxide in the platinum coordination sphere, [PtCl(O,O′‐acac)(DMSO)] (1) and [Pt(O,O′‐acac)(γ‐acac)(DMSO)] (2), have been synthesised and characterised by 1H, 13C, 195Pt 1‐D and 2‐D NMR heteronuclear correlation spectroscopy and, in the case of 2, by X‐ray crystal structure analysis also. Moreover, a new synthetic pathway to obtain the previously reported complex K[Pt(O,O′‐acac)(γ‐acac)2] (3) has been developed. The data presented herein are consistent with a reaction mechanism which explains the subsequent steps of the coordination of multiple β‐diketonate li‐gands to platinum(II) complexes, where the first species formed contains one O,O′‐chelated acac group. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Carbon‐Rich Ruthenium Complexes Containing Bis(allenylidene) and Mixed Alkynyl−Allenylidene Bridges (Eur. J. Inorg. Chem. 3/2005)
Authors: Rigaut Stéphane , Perruchon Johann , Guesmi Salaheddine , Fave Claire , Touchard Daniel , Dixneuf Pierre H.
Published: January 2005

The cover picture shows two examples of stable polynuclear ruthenium systems containing delocalized carbon‐rich bridges with unusual topologies. In this work, the synthesis, the spectroscopic and voltammetric studies of a new family of bis(allenylidene) and mixed allenylidene−acetylide complexes are presented. The nature of the reduced species, which are mainly ligand‐centered, is pointed out by means of ESR and IR spectroscopy. The UV/Vis and electrochemical studies show the large influence of the bridge on the electronic interaction between the redox centers and the fine tuning of this property. These new conjugated molecules appear to be promising alternatives to the classical bis(acetylide) systems for the construction of metal‐containing unsaturated oligomers or polymers to mediate electron‐transfer processes. Details are discussed in the article by S. Rigaut, D. Touchard et al. on p. 447 ff.
Mercury Detection in Seawater Using a Mercaptoacetic Acid Modified Gold Microwire Electrode
Authors: Widmann Antje , van den Berg Constant M. G.
Published: January 2005

It is demonstrated here that it is possible to determine mercury in chloride containing media like seawater by anodic stripping voltammetry using a modified electrode. A gold microwire electrode is modified using mercaptoacetic acid (MAA) to eliminate the problem of calomel formation, allowing the mercury to become fully removed from the electrode surface after each scan. In a synthetic salt solution of KNO3 the sensitivity for mercury was found to be improved by the surface modification. In seawater the sensitivity was not significantly improved possibly because of complexation of the mercury by the abundant chloride; however, the MAA coating prevented the formation of calomel causing the background scan to be free of mercury. Measurements in seawater at various pH values demonstrated that mercury detection is possible at natural pH (around 8); however, best sensitivity was attained at pH 4.8 with a deposition time of 3 min. A peak for copper occurred at more negative potential but did not interfere at this pH. The calibration was linear between 0 and 37 nM mercury with a limit of detection of 1 nM mercury.
Improved Resolution of Local Metal Deposition by Means of Constant Distance Mode Scanning Electrochemical Microscopy
Authors: Turyan Iva , Etienne Mathieu , Mandler Daniel , Schuhmann Wolfgang
Published: January 2005

The potential assisted ion‐transfer between two immiscible electrolyte solutions has been implemented in scanning electrochemical microscopy (SECM) for depositing metal microstructures on conducting surfaces. An improved approach for local metal deposition is presented, taking advantage from a recently described non‐optical shear‐force detection system integrated in the SECM, which provided a current‐independent tip‐surface distance positioning. This allowed positioning of the micropipette in very close proximity to the surface without applying a potential during the approach, and hence, resulted in an improved resolution for metal deposition. Moreover, it allowed the use of potential pulses for a discontinuous delivery of metal ions over the liquid‐liquid interface. The advantages of this approach and its applicability for creating micro‐ and nanostructures are discussed.
Efficient preconditioning of the discrete adjoint equations for the incompressible Navier–Stokes equations
Authors: Schneider René , Jimack Peter K.
Published: January 2005

Preconditioning of the discrete adjoint equations is closely related to preconditioning the linear systems arising in the Newton linearization of the discretized flow equations. We investigate the use of an optimal preconditioner for both problems on the example of a finite element discretization of the steady state incompressible Navier–Stokes equations. It is demonstrated that complications arising from the use of a zero mean pressure condition in the problem formulation can be overcome by modifying the preconditioner suitably. Copyright © 2005 John Wiley & Sons, Ltd.
Adjoint sensitivity analysis for fluid flow with free surface
Authors: Gejadze I. Y. , Copeland G. J. M.
Published: January 2005

This paper develops the adjoint sensitivities to the free surface incompressible barotropic Euler equations in order to allow for the assimilation of measurements of currents and free surface elevations into an unsteady flow solution by boundary control. To calculate a variation in a surface variable, a mapping is used in the vertical to shift the problem into a fixed domain. Then a variation is evaluated from the Jacobian matrix of the mapping. After calculating a variation in the surface variable and applying the inverse transformation, the tangent linear model is considered in the original space where the adjoint equations are then derived. The method is demonstrated by application to an unsteady flow in an open channel (a 2D vertical section model). A wider application is to the construction of a fully three‐dimensional coastal ocean model that allows assimilation of tidal elevation and current data. Copyright © 2005 John Wiley & Sons, Ltd.
Numerical assessment of thermo‐acoustic instabilities in gas turbines
Authors: Benoit L. , Nicoud F.
Published: January 2005

A new methodology to assess the effect of the flame/acoustics coupling on the stability of the modes without combustion is presented. An asymptotic method is used to account for the acoustic flame transfer function. The efficiency and accuracy of the approach is demonstrated on an academic case similar to a Rijke tube configuration. Copyright © 2005 John Wiley & Sons, Ltd.
A predictor–corrector formulation for rigorous streamline simulation
Authors: King Michael J. , Osako Ichiro , Datta‐Gupta Akhil
Published: January 2005

Streamline simulators have received increased attention in the petroleum industry because of their ability to effectively handle multimillion cell detailed geologic models and large simulation models. The efficiency of streamline simulation has relied primarily on their ability to take large time steps with fewer pressure solutions within an IMPES formulation. However, unlike conventional finite difference simulators, no clear guidelines have been available for the choice of time step for pressure and velocity updates. This has remained largely an uncontrolled approximation, either managed by engineering judgment, or by potentially time‐consuming time step size sensitivity studies early in a project. This is clearly related to the lack of theoretical understanding of numerical stability and convergence for this solution method. Our results demonstrate a new ability to predict numerical stability for streamline simulation. The analysis of numerical convergence is beyond our current scope. Clearly, both stability and convergence are required for numerical solutions.

We will review the predictor–corrector streamline formulation recently introduced (SPE 79688, presented at the SPE Reservoir Simulation Symposium, Houston, TX, 3–5 February 2003). This formulation includes the treatment of transverse flux between streamlines, and for the first time provides a rigorous foundation for discussions of numerical stability. We extend those discussions to include the treatment of capillarity and of gravity. In all instances, we will recognize the limits of stability of the calculations through the use of a CFL number, or in the instance of capillarity, a diffusion number. Although the worked examples will all utilize explicit numerical techniques, in most instances, the use of implicit techniques will be obvious.

We demonstrate the validity and utility of our approach using a series of numerical experiments in homogeneous and heterogeneous ¼ five‐spot patterns at various mobility ratios. For the discussions of capillarity and of gravity we also provide one‐dimensional calculations to better understand our options for their treatment using operator splitting. For these numerical experiments, we pay particular attention to favourable mobility ratio displacements, as they are known to be challenging to streamline simulation. Our results clearly demonstrate the impact of the transverse flux correction on the accuracy of the solution and on the appropriate choice of time step, across a range of mobility ratios. The proposed approach eliminates much of the subjectivity associated with time step selection in streamline simulation, and provides a basis for automatic control of pressure time step within full field streamline applications. Copyright © 2005 John Wiley & Sons, Ltd.
Numerical modelling of solid particle motion using a new penalty method
Authors: Randrianarivelo T. N. , Pianet G. , Vincent S. , Caltagirone J. P.
Published: January 2005

The present article reports on an original implicit tensorial penalty method (ITPM) for modelling solid particle motion in an incompressible flow. The basic idea is to decompose the viscous stress tensor of Navier–Stokes equation into contributions representing elongation, pure shearing and rotation. An artificial viscosity is associated to each stress contribution. The penalty method is used to impose different stress components thanks to a generalized augmented Lagrangian method implemented by introducing four Lagrange multipliers. An iterative Uzawa algorithm is finally used to achieve the numerical solution. The classical problems of Couette's flow between two coaxial cylinders and the settling of a particle in a tank filled with a viscous fluid have been chosen to demonstrate the capability of the new method. Copyright © 2005 John Wiley & Sons, Ltd.
Is silence golden? A test of the incorporation of the effects of ill‐health on income and leisure in health state valuations
Authors: Sendi Pedram , Brouwer Werner B. F.
Published: January 2005

The objective of the present study was to evaluate whether people include the effects of ill‐health on income and leisure in quality of life valuation when the measure is silent on both. A convenience sample of 20 health professionals had to rate a health status on a visual analogue scale (VAS) without being explicitly asked to consider the effects of ill‐health on income and leisure. A majority of respondents (60%) does not consider income effects and 75% does consider the effects on leisure. Explicitly asking respondents to incorporate these effects lowers the valuation. Our results indicate that whatever separation between costs and effects is preferred, using quality of life measures which are silent on income and leisure, leads to either double‐counting or ignoring real costs or effects. Copyright © 2005 John Wiley & Sons, Ltd.
Effect of load cycling and in vitro degradation on resin‐dentin bonds using a self‐etching primer
Authors: Osorio R. , Toledano M. , Osorio E. , Aguilera F. S. , Tay F. R.
Published: January 2005

The objective of this study was to evaluate the effect of in vitro degradation and mechanical loading on microtensile bond strength (MTBS) and microleakage (ML) of a resin composite to dentin using a self‐etching primer adhesive [Clearfil SE Bond (SEB)] under two hydration statuses. Twenty‐four flat dentin surfaces were divided in groups: 1) blot‐dried, 2) air‐dried. SEB was applied and resin buildups were performed with Tetric Ceram. Specimens were divided in four subgroups: a) sectioned into beams, b) load cycled, c) beams were immersed in NaOCl for 5 h, d) load cycled and immersed in NaOCl. Beams were tested in tension. For ML testing, 80 Class V cavities were prepared and molars divided in subgroups as described above (in group c and d, specimens were kept in distilled water for 1 year, instead of the 5‐h NaOCl immersion). ML was assessed by dye penetration. Analysis of variance and multiple comparisons tests were used for MTBS. For ML, Mann‐Whitney U and Wilcoxon matched pairs signed ranked were used (p < 0.05). SEB applied to completely dehydrated dentin produced the highest MTBS, at 24‐h evaluation. In vitro degradation always decreased MTBS, and fatigue loading only diminished MTBS on dehydrated dentin. Load cycling increased dye penetration on dentin margins. Degradation always increased ML in both enamel and dentin margins. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res 72A: 399–408, 2005
Adhesiveness of dental resin‐based restorative materials investigated with atomic force microscopy
Authors: Fano L. , Fano V. , Ma W. Y. , Wang X. G. , Zhu F.
Published: January 2005

This study aimed to show that the polymerization contraction of dental methacrylate‐based materials, when used as adhesives on hard substrate, produces voids at the material‐substrate interface. This phenomenology is closely related with the nanoleakage and the sealing ability of these materials. One prime/bond system, three restorative composite resins, and one orthodontic bonding system were cured by using mirror‐like glass slides as a compliance‐free reference substrate. The adhesive surface was analyzed by atomic force microscopy, and the polymerization contraction of bulk material was tested by laser beam‐scanning method. Nanoperiodic structure of three‐dimensional (3D) images, section analysis, and roughness characteristics (Ra and Rz) indicated that polymerization contraction produced voids at the interface. When the adhesive surface was exposed to oral simulating fluids (water, ethanol, and lactic acid solutions), hydrolytic degradation involved some hundreds of nanometers in depth. In visible light‐cured (VLC) materials, the interface porosity decreased when an irradiation pause (∼2 min) was carried out during gelation. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 73B: 35–42, 2005
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

A 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

The 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

Synthetic 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

The 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

Tissue 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

Cells 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

The 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

Proteins 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

The 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

We 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

Hybrid 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

Schiff 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

The 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

The 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

A 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

Transceive 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.
Effect of intravascular‐to‐extravascular water exchange on the determination of blood‐to‐tissue transfer constant by magnetic resonance imaging
Authors: Cao Y. , Brown S. L. , Knight R. A. , Fenstermacher J. D. , Ewing J. R.
Published: January 2005

Water exchange across capillary walls couples intra‐ and extravascular (IV‐EV) protons and their magnetization. A bolus i.v. injection of an extracellular MRI contrast agent (MRCA) causes a large increase in the spin‐lattice relaxation rate, R1, of water protons in the plasma and blood cells within the capillaries and changes the effective relaxation rate R1eff in tissue via IV‐EV water exchange. An analysis of the effect of plasma‐red cell and IV‐EV water exchange on the MRI‐measured influx and permeability of capillaries to the MRCA is presented and focused on the brain and the blood–brain barrier. The effect of arrival of a bolus of an MRCA in the capillary on the relaxation rate R1eff in tissue via IV‐EV water exchange occurs more rapidly than the MRCA uptake in tissue and can dominate the initial time curve of the R1eff change before the MRCA uptake in tissue becomes significant. This raises the possibility that (tissue dependent) IV‐EV rate of exchange of water molecules can affect estimates of MRCA transfer constant. We demonstrate that an approach that considers IV‐EV water exchange and uses the theoretical model of blood–brain tracer distribution developed by Patlak et al. (J Cereb Blood Flow Metab 1983;3:1–7) can lead to an accurate estimate of the MRI‐determined influx rate constant of the MRCA and to an underestimation of the tissue blood volume. Magn Reson Med 53:282–293, 2005. © 2005 Wiley‐Liss, Inc.
MRI‐based technique for determining nonuniform deformations throughout the volume of articular cartilage explants
Authors: Neu C.P. , Hull M.L. , Walton J.H. , Buonocore M.H.
Published: January 2005

Articular cartilage is critical to the normal function of diarthrodial joints. Despite the importance of the tissue and the prevalence of cartilage degeneration (e.g., osteoarthritis), the technology required to noninvasively describe nonuniform deformations throughout the volume of the tissue has not been available until recently. The objectives of the work reported in this paper were to 1) describe a noninvasive technique (termed the cartilage deformation by tag registration (CDTR) technique) to determine nonuniform deformations in articular cartilage explants with the use of specialized MRI tagging and image processing methods, 2) evaluate the strain error of the CDTR technique using a custom MRI‐compatible phantom material, and 3) demonstrate the applicability of the CDTR technique to articular cartilage by determining 3D strain fields throughout the volume of a bovine articular cartilage explant. A custom MRI pulse sequence was designed to tag and image articular cartilage explants at 7 Tesla in undeformed and deformed states during the application of multiple load cycles. The custom pulse sequence incorporated the “delays alternating with nutations for tailored excitation” (DANTE) pulse sequence to apply tags. This was followed by a “fast spin echo” (FSE) pulse sequence to create images of the tags. The error analysis using the phantom material indicated that deformations can be determined with an error, defined as the strain precision, better than 0.83% strain. When this technique was applied to a single articular cartilage explant loaded in unconfined compression, hetereogeneous deformations throughout the volume of the tissue were evident. This technique potentially can be applied to determine normal cartilage deformations, analyze degenerated cartilage, and evaluate cartilage surgical repair and treatment methodologies. In addition, this technique may be applied to other soft tissues that can be appropriately imaged by MR. Magn Reson Med 53:321–328, 2005. © 2005 Wiley‐Liss, Inc.
Ultrashort TE chemical shift imaging (UTE‐CSI)
Authors: Robson Matthew D. , Tyler Damian J. , Neubauer Stefan
Published: January 2005

A fundamental modification to the conventional chemical shift imaging (CSI) method is described that improves the imaging of species with short T2's (i.e., less than ∼2 ms). This approach minimizes the delay before each k‐space point is collected. This results in different time delays, Td, for different free induction decay (FID) acquisitions in k‐space. On a clinical 1.5T system this yields an effective delay due to transmit/receive switching of 70 μs and an echo time (TE) from the center of the excitation pulse to the center of k‐space of 170 μs, as compared with 1–2 ms for conventional CSI techniques. Using this method, the signal decay before acquisition is greatly reduced, thus enabling imaging of species with very short T2 (e.g., 200 μs) and increasing the signal‐to‐noise ratio (SNR) of species with intermediate T2. Increases in the SNR of the short T2 components of 23Na in the heart, and 31P acquisitions of bone are about 27% and 400%, respectively, compared to an optimized conventional CSI approach. The imperfections of this approach are also described, and the magnitude of the resultant image artifacts is quantified for different practical imaging situations. These artifacts were not found to be significant in the described applications. This new method allows us to obtain information on short T2 components without degrading the image quality from long T2 components. Magn Reson Med 53:267–274, 2005. © 2005 Wiley‐Liss, Inc.
Noninvasive MR thermometry using paramagnetic lanthanide complexes of 1,4,7,10‐tetraazacyclodoecane‐α,α′,α″,α‴‐tetramethyl‐1,4,7,10‐tetraacetic acid (DOTMA4–)
Authors: Hekmatyar S.K. , Hopewell Paige , Pakin Sait Kubilay , Babsky Andriy , Bansal Navin
Published: January 2005

Noninvasive techniques to monitor temperature have numerous useful biomedical applications. However, MR thermometry techniques based on the chemical shift, relaxation rates, and molecular diffusion rate of the water 1H signal suffer from poor thermal resolution. The feasibility of MR thermometry based on the strong temperature dependence of the hyperfine‐shifted 1H signal from the paramagnetic lanthanide complex thulium‐1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetate (TmDOTA–) was recently demonstrated. The use of paramagnetic lanthanide complexes for MR thermometry can be further enhanced by improving the signal‐to‐noise ratio (SNR) of the observed signal. In this study, the use of lanthanide complexes of a methyl‐substituted analog of DOTA4–, 1,4,7,10‐tetramethyl 1,4,7,10‐tetra azacyclodoecane‐1,4,7,10‐tetraacetic acetate (DOTMA4–) was evaluated. DOTMA4– complexes have 12 magnetically equivalent methyl protons, which provide an intense and sharper resonance compared to the corresponding DOTA– complexes. Experiments with paramagnetic Pr3+, Yb3+, Tb3+, Dy3+, and Tm3+ complexes of DOTMA4– showed that the Tm3+ complex is most favorable for MR thermometery because of the high temperature dependence of its chemical shift and its relatively narrow linewidth. The chemical shift of the methyl 1H signal from TmDOTMA– was ∼60 times more sensitive to temperature than the water 1H shift and was insensitive to changes in concentration, pH, [Ca2+], or the presence of other ions and macromolecules. The application of TmDOTMA– for measuring temperature in a subcutaneously implanted tumor model was demonstrated. Lastly, the feasibility of obtaining 3D images from the methyl 1H resonance of TmDOTMA– was demonstrated in phantom and live animal experiments. Overall, TmDOTMA– appears to be a promising probe for MR thermometry in vivo. Magn Reson Med 53:294–303, 2005. © 2005 Wiley‐Liss, Inc.