bluuebunny/crossref_metadata_2025_split huggingface dataset:
Access of Antibody Molecules to the Conserved Coreceptor Binding Site on Glycoprotein gp120 Is Sterically Restricted on Primary Human Immunodeficiency Virus Type 1
Authors: Labrijn Aran F. , Poignard Pascal , Raja Aarti , Zwick Michael B. , Delgado Karla , Franti Michael , Binley James , Vivona Veronique , Grundner Christoph , Huang Chih-Chin , Venturi Miro , Petropoulos Christos J. , Wrin Terri , Dimitrov Dimiter S. , Robinson James , Kwong Peter D. , Wyatt Richard T. , Sodroski Joseph , Burton Dennis R. 
Published: September 2003

ABSTRACT
Anti-human immunodeficiency virus type 1 (HIV-1) antibodies whose binding to gp120 is enhanced by CD4 binding (CD4i antibodies) are generally considered nonneutralizing for primary HIV-1 isolates. However, a novel CD4i-specific Fab fragment, X5, has recently been found to neutralize a wide range of primary isolates. To investigate the precise nature of the extraordinary neutralizing ability of Fab X5, we evaluated the abilities of different forms (immunoglobulin G [IgG], Fab, and single-chain Fv) of X5 and other CD4i monoclonal antibodies to neutralize a range of primary HIV-1 isolates. Our results show that, for a number of isolates, the size of the neutralizing agent is inversely correlated with its ability to neutralize. Thus, the poor ability of CD4i-specific antibodies to neutralize primary isolates is due, at least in part, to steric factors that limit antibody access to the gp120 epitopes. Studies of temperature-regulated neutralization or fusion-arrested intermediates suggest that the steric effects are important in limiting the binding of IgG to the viral envelope glycoproteins after HIV-1 has engaged CD4 on the target cell membrane. The results identify hurdles in using CD4i epitopes as targets for antibody-mediated neutralization in vaccine design but also indicate that the CD4i regions could be efficiently targeted by small molecule entry inhibitors.
Exploitation of Nucleic Acid Packaging Signals To Generate a Novel Influenza Virus-Based Vector Stably Expressing Two Foreign Genes
Authors: Watanabe Tokiko , Watanabe Shinji , Noda Takeshi , Fujii Yutaka , Kawaoka Yoshihiro 
Published: September 2003

ABSTRACT

At the final step in viral replication, the viral genome must be incorporated into progeny virions, yet the genomic regions required for this process are largely unknown in RNA viruses, including influenza virus. Recently, it was reported that both ends of the neuraminidase (NA) coding region are critically important for incorporation of this vRNA segment into influenza virions (Y. Fujii, H. Goto, T. Watanabe, T. Yoshida, and Y. Kawaoka, Proc. Natl. Acad. Sci. USA
100:
2002-2007, 2003). To determine the signals in the hemagglutinin (HA) vRNA required for its virion incorporation, we made a series of deletion constructs of this segment. Subsequent analysis showed that 9 nucleotides at the 3′ end of the coding region and 80 nucleotides at the 5′ end are sufficient for efficient virion incorporation of the HA vRNA. The utility of this information for stable expression of foreign genes in influenza viruses was assessed by generating a virus whose HA and NA vRNA coding regions were replaced with those of vesicular stomatitis virus glycoprotein (VSVG) and green fluorescent protein (GFP), respectively, while retaining virion incorporation signals for these segments. Despite the lack of HA and NA proteins, the resultant virus, which possessed only VSVG on the virion surface, was viable and produced GFP-expressing plaques in cells even after repeated passages, demonstrating that two foreign genes can be incorporated and maintained stably in influenza A virus. These findings could serve as a model for the construction of influenza A viruses designed to express and/or deliver foreign genes.
Relationship among Location of T-Antigen-Induced DNA Distortion, Auxiliary Sequences, and DNA Replication Efficiency
Authors: Okuley Susan , Call Mindy , Mitchell Tara , Hu Bugen , Woodworth Mary E. 
Published: September 2003

ABSTRACT

T-antigen-induced DNA distortion was studied in a series of simian virus 40 (SV40) plasmid constructs whose relative replication efficiency ranges from 0.2 to 36. Bending was detected in the wild-type SV40 regulatory region consisting of three copies of the GC-rich 21-bp repeat but not in constructs with only one or two copies of the 21-bp repeat. In a construct with enhanced replication efficiency, bending occurred in a 69-bp cellular sequence located upstream of a single copy of the 21-bp repeat. Bending occurred both upstream of
ori
and in the three 21-bp repeats located downstream of
ori
in a construct with reduced replication efficiency. In a construct with no 21-bp repeats, DNA distortion occurred downstream of
ori
. The results indicate that SV40 DNA replication is enhanced when the structure of the regulatory region allows the DNA to form a bent structure upstream of the initial movement of the replication fork.
Dynamics of Subgenomic Hepatitis C Virus Replicon RNA Levels in Huh-7 Cells after Exposure to Nucleoside Antimetabolites
Authors: Stuyver Lieven J. , McBrayer Tamara R. , Tharnish Phillip M. , Hassan Abdalla E. A. , Chu Chung K. , Pankiewicz Krzysztof W. , Watanabe Kyochi A. , Schinazi Raymond F. , Otto Michael J. 
Published: September 2003

ABSTRACT
Treatment with antimetabolites results in chemically induced low nucleoside triphosphate pools and cell cycle arrest in exponentially growing cells. Since steady-state levels of hepatitis C virus (HCV) replicon RNA were shown to be dependent on exponential growth of Huh-7 cells, the effects of antimetabolites for several nucleoside biosynthesis pathways on cell growth and HCV RNA levels were investigated. A specific anti-HCV replicon effect was defined as (i) minimal interference with the exponential cell growth, (ii) minimal reduction in cellular host RNA levels, and (iii) reduction of the HCV RNA copy number per cell compared to that of the untreated control. While most antimetabolites caused a cytostatic effect on cell growth, only inhibitors of the de novo pyrimidine ribonucleoside biosynthesis mimicked observations seen in confluent replicon cells, i.e., cytostasis combined with a sharp decrease in replicon copy number per cell. These results suggest that high levels of CTP and UTP are critical parameters for maintaining the steady-state level replication of HCV replicon in Huh-7 cells.
New Developments in Transmission Electron Microscopy for Nanotechnology
Authors: Wang Z.L. 
Published: September 2003

AbstractHigh‐resolution transmission electron microscopy (HRTEM) is one of the most powerful tools used for characterizing nanomaterials, and it is indispensable for nanotechnology. This paper reviews some of the most recent developments in electron microscopy techniques for characterizing nanomaterials. The review covers the following areas: in‐situ microscopy for studying dynamic shape transformation of nanocrystals; in‐situ nanoscale property measurements on the mechanical, electrical and field emission properties of nanotubes/nanowires; environmental microscopy for direct observation of surface reactions; aberration‐free angstrom‐resolution imaging of light elements (such as oxygen and lithium); high‐angle annular‐dark‐field scanning transmission electron microscopy (STEM); imaging of atom clusters with atomic resolution chemical information; electron holography of magnetic materials; and high‐spatial resolution electron energy‐loss spectroscopy (EELS) for nanoscale electronic and chemical analysis. It is demonstrated that the picometer‐scale science provided by HRTEM is the foundation of nanometer‐scale technology.
Sex‐specific patterns of galanin, cholecystokinin, and substance P expression in neurons of the principal bed nucleus of the stria terminalis are differentially reflected within three efferent preoptic pathways in the juvenile rat
Authors: Polston Eva K. , Simerly Richard B. 
Published: September 2003

AbstractNeurons in the principal bed nucleus of the stria terminalis (BSTp) integrate hormonal and sensory information associated with reproduction and transmit this information to hypothalamic nuclei that regulate neuroendocrine and behavioral functions. The neuropeptides galanin (GAL), cholecystokinin (CCK), and substance P (SP) are highly expressed in BSTp neurons and are differentially regulated by sex steroids. The current experiments investigated whether developmental or peripubertal hormone‐mediated changes in GAL, CCK, and SP expression are reflected within efferent pathways to the preoptic structures that regulate gonadotropin secretion and sexual behavior. Anterograde labeling of projections from the BSTp of male and female juvenile rats combined with immunohistochemical labeling of GAL‐, CCK‐, and SP‐containing fibers in the anteroventral periventricular preoptic nucleus (AVPV) and the central and medial divisions of the medial preoptic nucleus (MPNc, MPNm, respectively) revealed unique sex differences in each region. In the AVPV, Phaseolus vulgaris leucoagglutinin‐labeled fibers were seen at a greater density in males than in females, and higher percentages of these fibers contained GAL in males than in females. In contrast, fibers projecting from the BSTp to the MPNc were more likely to contain SP in females than in males. Treatment of gonadectomized, peripubertal males and females with exogenous testosterone and estradiol did not alter the densities of GAL‐, CCK‐, or SP‐containing fibers in any of the three brain areas examined. Collectively, these results suggest that patterns of neuropeptide expression in BSTp projections are established during development, resulting in a distinct, stable, and sex‐specific chemoarchitectural profile for each projection pathway. J. Comp. Neurol. 465:551–559, 2003. © 2003 Wiley‐Liss, Inc.
Diversity of glycine receptors in the mouse retina: Localization of the α3 subunit
Authors: Haverkamp Silke , Müller Ulrike , Harvey Kirsten , Harvey Robert J. , Betz Heinrich , Wässle Heinz 
Published: September 2003

AbstractGlycine receptors (GlyRs) and their role in retinal circuitry were analyzed immunocytochemically in wild‐type and GlyR α3 subunit–deficient (Glra3−/−) mouse retinae. GlyRs are localized in the inner plexiform layer in brightly fluorescent puncta, which are likely to represent postsynaptically clustered GlyRs. Approximately one third of the clusters were found to contain the α1 subunit, and half possessed the α3 subunit. However, these two GlyR isoforms were localized at different glycinergic synapses. In the Glra3−/− mouse, α3 subunit clusters were completely eliminated, although the total number of GlyR clusters was only slightly reduced. This finding indicates that other GlyR subunits (such as α2 or α4) may have compensated for the loss of the α3 subunit. Characteristic expression patterns of the α1 and α3 subunits within the synaptic circuits of the retina were revealed by double labeling sections for GlyRs and markers that define specific retinal neurons. The α1 subunit mediates signal transfer in the rod pathway between AII amacrine cells and OFF‐cone bipolar cells. In contrast, the α3 subunit appears to be predominantly involved with the cone pathways. Thus, expression of different GlyR α subunit genes correlates with anatomically defined connectivities. J. Comp. Neurol. 465:524–539, 2003. © 2003 Wiley‐Liss, Inc.
Hypothalamic orexin (hypocretin) neurons express vesicular glutamate transporters VGLUT1 or VGLUT2
Authors: Rosin Diane L. , Weston Matthew C. , Sevigny Charles P. , Stornetta Ruth L. , Guyenet Patrice G. 
Published: September 2003

AbstractInitially recognized for their importance in control of appetite, orexins (also called hypocretins) are neuropeptides that are also involved in regulating sleep, arousal, and cardiovascular function. Loss of orexin appears to be the primary cause of narcolepsy. Cells expressing the orexins are restricted to a discrete region of the hypothalamus, but their terminal projections are widely distributed throughout the brain. With the diversity of function and broad distribution of orexin terminals, it is not known whether the orexin cells constitute a homogeneous population. Because orexins produce neuroexcitatory effects, we hypothesized that orexin‐containing neurons are glutamatergic. In the present study we used digoxigenin‐labeled cRNA probes for the vesicular glutamate transporters, VGLUT1 and VGLUT2, for in situ hybridization studies in combination with immunohistochemical detection of orexin cell bodies in the hypothalamus. In general, cells in the hypothalamus expressed low levels of the vesicular glutamate transporters relative to other areas of the forebrain, such as the cortex and thalamus. Light labeling for VGLUT2 mRNA was detected in about 50% of the orexin‐immunoreactive neurons, and a much smaller percentage (≈13%) of orexin‐immunoreactive cells was found to express VGLUT1. Despite the fact that intense labeling for GAD67 mRNA was found in a large number of cells throughout the hypothalamus, none of the orexin‐immunoreactive cells was found to be GABAergic. These findings, showing that many of the orexin neurons are glutamatergic, are consistent with the neuroexcitatory effects of orexin but suggest that another neurochemical phenotype may define the remaining subset of orexin neurons. J. Comp. Neurol. 465:593–603, 2003. © 2003 Wiley‐Liss, Inc.
Experimental study of the connections of the gustatory system in the rainbow trout, Oncorhynchus mykiss
Authors: Folgueira Mónica , Anadón Ramón , Yáñez Julián 
Published: September 2003

AbstractSalmonids are a group of teleosts with a nonspecialized gustatory system. With the aim of describing the gustatory connections in a member of this group, we carried out tract‐tracing experiments using the lipophilic carbocyanine dye 1,1′‐dioctadecyl 3,3,3′,3′‐tetramethylindocarbocyanine perchlorate (DiI) in fixed brains of the rainbow trout (Oncorhynchus mykiss). The neural tracer was applied to the primary viscerosensory column, secondary gustatory visceral nucleus (SGN), torus lateralis (TL), and tertiary gustatory nucleus (TGN), the dorsal part of the ventral area of the telencephalon (dorsal‐Vv), and the medial area of the dorsal telencephalon (Dm). The primary viscerosensory column projects mainly to the SGN. DiI application to the SGN showed a bilateral and reciprocal connection with the TGN and a rostral portion of the nucleus of the lateral hypothalamic recess. The application of DiI in the dorsal‐Vv and Dm at levels rostral to the anterior commissure led to labeling of a restricted group of diencephalic neurons in the TGN and sending dendrites to the TL. DiI application to the TL/TGN anterogradely labeled fibers that coursed in the medial forebrain bundle innervating the precommissural portion of the dorsal‐Vv and Dm. Caudally, this type of application led to labeling of fibers in the viscerosensory column and perikarya in the SGN. Tract‐tracing results showed direct projections from the diencephalic and rhombencephalic gustatory nuclei to the telencephalon. There was a direct and reciprocal connection between the SGN and the ventral telencephalon. The results showed that the gustatory connections of the trout are similar to those of teleosts, with highly specialized gustatory centers as in cyprinids and ictalurids, and to that observed in the percomorph tilapia, thus demonstrating a basic organization that is shared by most teleosts. J. Comp. Neurol. 465:604–619, 2003. © 2003 Wiley‐Liss, Inc.
New Insights into the Jahn–Teller Effect through ab initio Quantum‐Mechanical/Molecular‐Mechanical Molecular Dynamics Simulations of CuII in Water
Authors: Schwenk Christian F. , Rode Bernd M. 
Published: September 2003

AbstractThe CuII hydration shell structure has been studied by means of classical molecular dynamics (MD) simulations including three‐body corrections and hybrid quantum‐mechanical/molecular‐mechanical (QM/MM) molecular dynamics (MD) simulations at the Hartree–Fock level. The copper(II) ion is found to be six‐fold coordinated and [Cu(H2O)6]2+ exhibits a distorted octahedral structure. The QM/MM MD approach reproduces correctly the experimentally observed Jahn–Teller effect but exhibits faster inversions (<200 fs) and a more complex behaviour than expected from experimental data. The dynamic Jahn–Teller effect causes the high lability of [Cu(H2O)6]2+ with a ligand‐exchange rate constant some orders of magnitude higher than its neighbouring ions NiII and ZnII. Nevertheless, no first‐shell water exchange occurred during a 30‐ps simulation. The structure of the hydrated ion is discussed in terms of radial distribution functions, coordination numbers, and various angular distributions and the dynamical properties as librational and vibrational motions and reorientational times were evaluated, which lead to detailed information about the first hydration shell. Second‐shell water‐exchange processes could be observed within the simulation time scale and yielded a mean ligand residence time of ≈20 ps.
Molecular Spin Clusters: New Synthetic Approaches and Neutron Scattering Studies
Authors: Basler Reto , Boskovic Colette , Chaboussant Grégory , Güdel Hans U. , Murrie Mark , Ochsenbein Stefan T. , Sieber Andreas 
Published: September 2003

AbstractWe review our recent work in the field of molecular spin clusters and single‐molecule magnets, showing how inelastic neutron scattering (INS) can be used to determine magnetic exchange interactions and anisotropy splittings. A general introduction to neutron scattering precedes selected examples, building upon the first determination of exchange coupling in a transition metal complex using INS, through anisotropic exchange in cobalt(II) spin clusters to the determination of exchange interactions in a dodecanuclear nickel(II) wheel. The strength of INS for the accurate determination of anisotropy splittings in single‐molecule magnets is revealed. Not only can one determine the axial zero‐field splitting parameter D, which plays a key role in single‐molecule magnet behavior, but also higher‐order terms important in understanding the quantum tunneling behavior. Finally, we review two of our synthetic approaches towards new single‐molecule magnets based on nickel, manganese, and iron.
Ionic Liquid for in situ Vis/NIR and Raman Spectroelectrochemistry: Doping of Carbon Nanostructures
Authors: Kavan Ladislav , Dunsch Lothar 
Published: September 2003

Abstract1‐butyl‐3‐methylimidazolium tetrafluoroborate (an ionic liquid) is an advantageous electrolyte for the study of charge‐transfer reactions at single‐walled carbon nanotubes (SWCNTs) and fullerene peapods (C60@SWCNT). Compared to traditional electrolyte solutions, this medium offers a broader window of electrochemical potentials to be applied, and favorable optical properties for in situ Vis/NIR and Raman spectroelectrochemistry of nano‐carbon species. The electrochemistry of both nanotubes and peapods is dominated by their capacitive double‐layer charging. Vis/NIR spectroelectrochemistry confirms the charging‐induced bleaching of transitions between Van Hove singularities. At high positive potentials, new optical transitions were activated in partly filled valence band. The bleaching of optical transitions is mirrored by the quenching of resonance Raman scattering in the region of tube‐related modes. The Raman frequency of the tangential displacement mode of SWCNT shifts to blue upon both anodic and cathodic charging in the ionic liquid. The Raman modes of intratubular C60 exhibit a considerable intensity increase upon anodic doping of peapods.
Long‐Range Transport in an Assembly of ZnO Quantum Dots: The Effects of Quantum Confinement, Coulomb Repulsion and Structural Disorder
Authors: Roest Aarnoud L. , Germeau Alexander , Kelly John J. , Vanmaekelbergh Daniël , Allan Guy , Meulenkamp Eric A. 
Published: September 2003

AbstractWe have studied the storage and long‐range transport of electrons in a porous assembly of weakly coupled ZnO quantum dots permeated with an aqueous and a propylene carbonate electrolyte solution. The number of electrons per ZnO quantum dot is controlled by the electrochemical potential of the assembly; the charge of the electrons is compensated by ions present in the pores. We show with optical and electrical measurements that the injected electrons occupy the S, P, and D type conduction electron levels of the quantum dots; electron storage in surface states is not important. With this method of three‐dimensional charge compensation, up to ten electrons per quantum‐dot can be stored if the assembly is permeated with an aqueous electrolyte. The screening of the electron charge is less effective in the case of an assembly permeated with a propylene carbonate electrolyte solution. Long‐range electron transport is studied with a transistor set‐up. In the case of ZnO assemblies permeated with an aqueous electrolyte, two quantum regimes are observed corresponding to multiple tunnelling between the S orbitals (at a low occupation) and P orbitals (at a higher occupation). In a ZnO quantum‐dot assembly permeated with a propylene carbonate electrolyte solution, there is a strong overlap between these two regimes.
Crosslinked Copolyimide Membranes for Phenol Recovery from Process Water by Pervaporation
Authors: Pithan Frankie , Staudt‐Bickel Claudia 
Published: September 2003

AbstractThe effectiveness of different copolyimide membranes in the process of recovering phenol from water by pervaporation has been investigated. The polyimides were obtained by the polycondensation of 6FDA (4,4′‐hexafluoro‐isopropylidene diphthalic anhydride) with different diamines. The diamines 4MPD (2,3,5,6‐tetramethyl‐1,4‐phenylene diamine), 6FpDA (4,4′‐hexafluoro‐isopropylidene dianiline), 6FpODA (4,4′‐bis‐(4′‐aminophenoxyphenyl)hexafluoropropane), and DABA (3,5‐diaminobenzoic acid) as a monomer providing a crosslinkable group, were used. In order to reach chemical stability at high phenol concentrations, the polymer structures were crosslinked with 1,10‐decanediol and OFHD (2,2,3,3,4,4,5,5‐octafluorohexanediol). Pervaporation experiments were performed at 60 °C, covering a concentration range of phenol between 2 and 11 wt. %. The best separation characteristics were obtained with a 6FDA‐6FpDA/DABA 2:1 membrane crosslinked with 1,10‐decanediol. Using a 7.8 wt. % phenol feed mixture, a total flux of 14 kg μm m−2 h−1 was reached with an enrichment of 40 wt. % phenol in the permeate. It was found that conditioning the membrane using high phenol concentrations (between 8 and 11 wt. %) is a necessary pretreatment in order to enhance the flux and improve enrichment, especially if process water with low phenol concentrations is to be treated. In addition to the experimental results, a comparison with rubbery membrane materials is presented in the discussion.
Electrochemical Studies of Vitamin K1Microdroplets: Electrocatalytic Hydrogen Evolution
Authors: Wain Andrew J. , Wadhawan Jay D. , Compton Richard G. 
Published: September 2003

AbstractThe voltammetry of a basal‐plane pyrolytic graphite electrode modified with a random ensemble of unsupported microdroplets of vitamin K1is investigated when the electrode is immersed in aqueous electrolytes. It is shown that in dilute acidic solutions, electroreduction occurs in a single two‐electron two‐proton process to yield the corresponding hydroquinone at the electrode|vitamin K1microdroplet|aqueous‐electrolyte three‐phase boundary. On addition of ionic alkali‐metal salts to the aqueous acidic phase, the electrochemical reduction of vitamin K1to the quinol is accompanied by catalytic hydrogen evolution within and alkali‐metal‐cation insertion into the organic microdroplets. In strongly alkaline solutions, electrochemical reduction of vitamin K1at the triple‐phase junction is proposed as being a single two‐electron process with concomitant uptake of alkali‐metal cations in order to maintain electroneutrality within the oil phase. Surprisingly, the relative ease of cation insertion into the oil phase is demonstrated to be governed by the degree of ion‐pair formation rather than by the Gibbs transfer energy of the cation across the liquid|liquid interface.