bluuebunny/crossref_metadata_2025 huggingface dataset:
Viremia and Nasal and Rectal Shedding of Rotavirus in Gnotobiotic Pigs Inoculated with Wa Human Rotavirus
Authors: Azevedo M. S. , Yuan L. , Jeong K.-I. , Gonzalez A. , Nguyen T. V. , Pouly S. , Gochnauer M. , Zhang W. , Azevedo A. , Saif L. J.
Published: April 2005

Respiratory symptoms with rotavirus shedding in nasopharyngeal secretions have been reported in children with and without gastrointestinal symptoms (Zheng et al., 1991, J. Med. Virol.
34:
29-37). To investigate if attenuated and virulent human rotavirus (HRV) strains cause upper respiratory tract infections or viremia in gnotobiotic pigs, we inoculated them with attenuated or virulent HRV intranasally, intravenously, or orally or via feeding tube (gavage) and assayed virus shedding. After oral or intranasal inoculation with attenuated HRV, the pigs remained asymptomatic, but 79 to 95% shed virus nasally and 5 to 17% shed virus rectally. After inoculation by gavage, no pigs shed virus nasally or rectally, but all pigs seroconverted with antibodies to HRV. No viremia was detected through postinoculation day 10. Controls inoculated intranasally with nonreplicating rotavirus-like particles or mock inoculated did not shed virus. In contrast, 100% of pigs inoculated with virulent HRV (oral, intranasal, or gavage) developed diarrhea, shed virus nasally and rectally, and had viremia. The infectivity of sera from the viremic virulent HRV-inoculated pigs was confirmed by inoculating gnotobiotic pigs orally with pooled HRV-positive serum. Serum-inoculated pigs developed diarrhea and fecal and nasal virus shedding and seroconverted with serum and intestinal HRV antibodies. Pigs inoculated intravenously with serum or intestinal contents from the viremic virulent HRV-inoculated pigs developed diarrhea, virus shedding, and viremia, similar to the orally inoculated pigs. This study provides new evidence that virulent HRV causes transient viremia and upper respiratory tract infection in addition to gastrointestinal infection in gnotobiotic pigs, confirming previous reports of rotavirus antigenemia (Blutt et al., Lancet
362:
1445-1449, 2003). Our data also suggest that intestinal infection might be initiated from the basolateral side of the epithelial cells via viremia. Additionally, virus shedding patterns indicate a different pathogenesis for attenuated versus virulent HRV.
Characterization of Prototype Foamy Virus Gag Late Assembly Domain Motifs and Their Role in Particle Egress and Infectivity
Authors: Stange Annett , Mannigel Ingrid , Peters Katrin , Heinkelein Martin , Stanke Nicole , Cartellieri Marc , Göttlinger Heinrich , Rethwilm Axel , Zentgraf Hanswalter , Lindemann Dirk
Published: April 2005

Foamy viruses (FV) are unusual among retroviruses since they require both Gag and Env structural proteins for particle egress. Recently significant progress has been made towards the mechanistic understanding of the viral release process, in particular that of retroviruses, and the viral domains and cellular pathways involved. However little is currently known about domains of FV structural proteins and cellular proteins engaged in this process. By mutational analysis of sequence motifs in prototype FV (PFV) Gag, bearing homology to known late assembly (L) domains, a PSAP motif with L domain function that was functionally interchangeable by heterologous L domains was identified. In contrast the inactivation of a PPPI motif had no significant influence on PFV particle release, although mutant viral particles displayed reduced infectivity. Similarly mutation of an evolutionary conserved YXXL motif revealed no classical L-domain function but resulted in release of noninfectious viruslike particles. Biochemical and electron microscopy analysis demonstrated that these mutant particles incorporated all viral structural proteins but contained aberrantly capsid structures, suggesting a role in capsid assembly for this PFV Gag sequence motif. In line with the mutational analysis, overexpression of dominant negative (DN) mutants and wild-type TSG101 but not the DN mutant of AIP-1/ALIX reduced PFV particle release and infectivity. Furthermore, DN mutants of Vps4A, Vps4B, and CHMP3 inhibited PFV egress and infectivity. Taken together these results demonstrate that PFV, like other viruses, requires components of the vacuolar protein sorting (VPS) machinery for egress and enters the VPS pathway through interaction with TSG101.
Pseudovirion Particle Production by Live Poxvirus Human Immunodeficiency Virus Vaccine Vector Enhances Humoral and Cellular Immune Responses
Authors: Chen Xuemin , Rock Michael T. , Hammonds Jason , Tartaglia James , Shintani Ayumi , Currier Jeff , Slike Bonnie , Crowe James E. , Marovich Mary , Spearman Paul
Published: April 2005

Live-vector-based human immunodeficiency virus (HIV) vaccines are an integral part of a number of HIV vaccine regimens currently under evaluation. Live vectors that carry an intactgaggene are capable of eliciting HIV pseudovirion particle formation from infected host cells. The impact of pseudovirion particle formation on the immune response generated by live HIV vaccine vectors has not been established. In this study, a canarypox HIV vaccine candidate vector expressing HIVgagandenvgenes, vCP205, was modified by the introduction of a glycine-to-alanine coding change in the N-terminal myristylation site ofgagto create Myr−vCP205. This substitution effectively eliminated particle formation without altering the level of protein production. vCP205 and Myr−vCP205 were then directly compared for the ability to induce HIV-specific immune responses in mice. The particle-competent vector vCP205 elicited higher levels of CD8+T-cell responses, as indicated by gamma interferon enzyme-linked immunospot (ELISPOT) assay and intracellular cytokine staining. Humoral responses to Gag and Env were also markedly higher from animals immunized with the particle-competent vector. Furthermore, HIV-specific CD4+T-cell responses were greater among animals immunized with the particle-competent vector. Using a human dendritic cell model of antigen presentation in vitro, vCP205 generated greater ELISPOT responses than Myr−vCP205. These results demonstrate that pseudovirion particle production by live-vector HIV vaccines enhances HIV-specific cellular and humoral immune responses.
An Unrelated Monoclonal Antibody Neutralizes Human Immunodeficiency Virus Type 1 by Binding to an Artificial Epitope Engineered in a Functionally Neutral Region of the Viral Envelope Glycoproteins
Authors: Ren Xinping , Sodroski Joseph , Yang Xinzhen
Published: April 2005

Neutralizing antibodies often recognize regions of viral envelope glycoproteins that play a role in receptor binding or other aspects of virus entry. To address whether this is a necessary feature of a neutralizing antibody, we identified the V4 region of the gp120 envelope glycoprotein of human immunodeficiency virus type 1 (HIV-1) as a sequence that is tolerant of drastic change and thus appears to play a negligible role in envelope glycoprotein function. An artificial epitope tag was inserted into the V4 region without a significant effect on virus entry or neutralization by antibodies that recognize HIV-1 envelope glycoprotein sequences. An antibody directed against the artificial epitope tag was able to neutralize the modified, but not the wild-type, HIV-1. Thus, the specific target of a neutralizing antibody need not contribute functionally to the process of virus entry.
Kaposi's Sarcoma-Associated Herpesvirus/Human Herpesvirus 8 Replication and Transcription Activator Regulates Viral and Cellular Genes via Interferon-Stimulated Response Elements
Authors: Zhang Jun , Wang Jinzhong , Wood Charles , Xu Dongsheng , Zhang Luwen
Published: April 2005

Kaposi's sarcoma-associated herpesvirus (also called human herpesvirus 8 [HHV-8]) replication and transcription activator (RTA) is apparently necessary and sufficient for the switch from viral latency to lytic replication. RTA may regulate open reading frame (ORF) K14 (viral OX-2 homologue) and ORF74 (viral G-protein-coupled receptor homologue) genes through an interferon-stimulated response element (ISRE)-like sequence (K14 ISRE) in the promoter region. RTA strongly activated a K14 ISRE-containing K14-ORF74 promoter reporter construct and a heterologous promoter reporter construct containing K14 ISRE. RTA could bind to K14 ISRE and other ISREs, activate promoter reporter constructs from interferon-simulated genes (ISGs), and selectively induce three endogenous ISGs in primary endothelial cells: ISG-54, myxovirus resistance protein 1 (MxA), and stimulated
trans
-acting factor of 50 kDa. In addition, a region in the RTA DNA-binding domain has been identified with certain sequence similarity to the DNA-binding domains of the interferon regulatory factor (IRF) family. Mutation in one conserved amino acid within this region reduced the ability of RTA to bind to ISRE as well as other RTA response elements. Furthermore, the mutant failed to activate RTA-responsive promoters and to induce viral lytic gene expression. The mutation at the same conserved amino acid residue in IRF-7 drastically reduced its ability to bind to DNA and to activate the beta interferon promoter. The sequence and functional similarities between RTA and IRFs suggest that the HHV-8 RTA may usurp the cellular IRF pathway.
Evolution of the Equine Infectious Anemia Virus Long Terminal Repeat during the Alteration of Cell Tropism
Authors: Maury Wendy , Thompson Robert J. , Jones Quentin , Bradley Sarahann , Denke Tara , Baccam Prasith , Smazik Matthew , Oaks J. Lindsay
Published: April 2005

Equine infectious anemia virus (EIAV) is a lentivirus with in vivo cell tropism primarily for tissue macrophages; however, in vitro the virus can be adapted to fibroblasts and other cell types. Tropism adaptation is associated with both envelope and long terminal repeat (LTR) changes, and findings strongly suggest that these regions of the genome influence cell tropism and virulence. Furthermore, high levels of genetic variation have been well documented in both of these genomic regions. However, specific EIAV nucleotide or amino acid changes that are responsible for cell tropism changes have not been identified. A study was undertaken with the highly virulent, macrophage-tropic strain of virus EIAV
wyo
to identify LTR changes associated with alterations in cell tropism. We found the stepwise generation of a new transcription factor binding motif within the enhancer that was associated with adaptation of EIAV to endothelial cells and fibroblasts. An LTR that contained the new motif had enhanced transcriptional activity in fibroblasts, whereas the new site did not alter LTR activity in a macrophage cell line. This finding supports a previous prediction that selection for new LTR genetic variants may be a consequence of cell-specific selective pressures. Additional investigations of the EIAV
wyo
LTR were performed in vivo to determine if LTR evolution could be detected over the course of a 3-year infection. Consistent with previous in vivo findings, we observed no changes in the enhancer region of the LTR over that time period, indicating that the EIAV
wyo
LTR was evolutionarily stable in vivo.
T-Cell Growth Transformation by Herpesvirus Saimiri Is Independent of STAT3 Activation
Authors: Heck Elke , Lengenfelder Doris , Schmidt Monika , Müller-Fleckenstein Ingrid , Fleckenstein Bernhard , Biesinger Brigitte , Ensser Armin
Published: April 2005

Herpesvirus saimiri (saimirine herpesvirus 2) (HVS), a T-lymphotropic tumor virus, induces lymphoproliferative disease in several species of New World primates. In addition, strains of HVS subgroup C are able to transform T cells of Old World primates, including humans, to permanently growing T-cell lines. In concert with the Stp oncoprotein, the tyrosine kinase-interacting protein (Tip) of HVS C488 is required for T-cell transformation in vitro and lymphoma induction in vivo. Tip was previously shown to interact with the protein tyrosine kinase Lck. Constitutive activation of signal transducers and activators of transcription (STATs) has been associated with oncogenesis and has also been detected in HVS-transformed T-cell lines. Furthermore, Tip contains a putative consensus YXPQ binding motif for the SH2 (srchomology 2) domains of STAT1 and STAT3. Tip tyrosine phosphorylation at this site was required for binding of STATs and induction of STAT-dependent transcription. Here we sought to address the relevance of STAT activation for transformation of human T cells by introducing a tyrosine-to-phenylalanine mutation in the YXPQ motif of Tip of HVS C488. Unexpectedly, the recombinant virus was still able to transform human T lymphocytes, but it had lost its capability to activate STAT3 as well as STAT1. This demonstrates that growth transformation by HVS is independent of STAT3 activation.
Rapid Viral Escape at an Immunodominant Simian-Human Immunodeficiency Virus Cytotoxic T-Lymphocyte Epitope Exacts a Dramatic Fitness Cost
Authors: Fernandez Caroline S. , Stratov Ivan , De Rose Robert , Walsh Katrina , Dale C. Jane , Smith Miranda Z. , Agy Michael B. , Hu Shiu-lok , Krebs Kendall , Watkins David I. , O'Connor David H. , Davenport Miles P. , Kent Stephen J.
Published: April 2005

Escape from specific T-cell responses contributes to the progression of human immunodeficiency virus type 1 (HIV-1) infection. T-cell escape viral variants are retained following HIV-1 transmission between major histocompatibility complex (MHC)-matched individuals. However, reversion to wild type can occur following transmission to MHC-mismatched hosts in the absence of cytotoxic T-lymphocyte (CTL) pressure, due to the reduced fitness of the escape mutant virus. We estimated both the strength of immune selection and the fitness cost of escape variants by studying the rates of T-cell escape and reversion in pigtail macaques. Near-complete replacement of wild-type with T-cell escape viral variants at an immunodominant simian immunodeficiency virus Gag epitope KP9 occurred rapidly (over 7 days) following infection of pigtail macaques with SHIV
SF162P3
. Another challenge virus, SHIV
mn229
, previously serially passaged through pigtail macaques, contained a KP9 escape mutation in 40/44 clones sequenced from the challenge stock. When six KP9-responding animals were infected with this virus, the escape mutation was maintained. By contrast, in animals not responding to KP9, rapid reversion of the K165R mutation occurred over 2 weeks after infection. The rapidity of reversion to the wild-type sequence suggests a significant fitness cost of the T-cell escape mutant. Quantifying both the selection pressure exerted by CTL and the fitness costs of escape mutation has important implications for the development of CTL-based vaccine strategies.
Tumorigenic Poxviruses Up-Regulate Intracellular Superoxide To Inhibit Apoptosis and Promote Cell Proliferation
Authors: Teoh Melissa L. T. , Turner Patricia V. , Evans David H.
Published: April 2005

Tumorigenic leporipoxviruses encode catalytically inactive homologs of cellular Cu-Zn superoxide dismutase (SOD1). The function of the orthologous myxoma virus M131R and Shope fibroma virus S131R gene products is uncertain, but they inhibit SOD1 activity by a process linked to binding its copper chaperone. Using a superoxide-sensitive dye (hydroethidine), we observed that virus infection increased intracellular superoxide levels in an M/S131R-dependent manner. To see whether this effect promotes infection, we deleted the Shope fibroma virus S131R gene and compared the clinical manifestations of wild-type and mutant virus infections in rabbits. S131RΔ virus produced significantly smaller fibroxanthosarcoma-like growths in vivo and, at a point where these growths were already receding, wild-type infections still showed extensive leukocyte infiltration, necrosis, and fibromatous cell proliferation. Coincidentally, whereas Jurkat cells are protected from mitochondria- and Fas-mediated apoptosis by wild-type myxoma virus in vitro, M131RΔ virus could not block Fas-initiated apoptosis as judged by DNA laddering, terminal deoxynucleotidyltransferase-mediated dUTP-fluorescein nick end labeling, and caspase 3 cleavage assays. These data suggest that tumorigenic poxviruses can modulate intracellular redox status to their advantage to stimulate infected cell growth and inhibit programmed cell death.
PHASE SHIFT ANALYSIS OF PT-SYMMETRIC NONHERMITIAN EXTENSION OF AN-1 CALOGERO MODEL WITHOUT CONFINING INTERACTION
Authors: BASU-MALLICK B. , BHATTACHARYYA TANAYA , MANDAL BHABANI PRASAD
Published: April 2005

We discuss a manyparticle quantum system, which is obtained by adding some nonhermitian but PT (i.e. combined parity and time reversal) invariant interaction to the AN-1 rational Calogero model without confining potential. This model gives rise to scattering states with continuous real spectrum. The scattering phase shift is determined through the exchange statistics parameter. We find that, unlike the case of the usual Calogero model, the exclusion and exchange statistics parameter differ from each other in the presence of PT invariant interaction.
PHOTO-EXCITED ZERO-RESISTANCE STATES IN THE GaAs/AlGaAs SYSTEM
Authors: MANI R. G.
Published: April 2005

The microwave-excited high mobility two-dimensional electron system exhibits, at liquid helium temperatures, vanishing resistance in the vicinity of B=[4/(4j+1)]Bf, where Bf=2πfm*/e, m* is an effective mass, e is the charge, and f is the microwave frequency. Here, we summarize some experimental results.
THE EFFECT OF THE MICROSCOPIC STATE OF A BALLISTIC RING ON THE AHARONOV-BOHM OSCILLATIONS TEMPERATURE DEPENDENCE
Authors: OLSHANETSKY E. B. , KVON Z. D. , SHEGLOV D. V. , LATYSHEV A. V. , TOROPOV A. I. , RENARD V. , PORTAL J. C.
Published: April 2005

In the present work we study the electron transport properties of small (≈ 100 nm) ring interferometers fabricated by the local anodic oxidation of a AlGaAs / GaAs heterostructures containing 2D electron gas. Owing to the small size of the rings the Aharonov-Bohm (AB) oscillations in them can be observed at temperatures as high as 9 K. It has been found that the temperature dependence of AB oscillations amplitude in these rings is sensitive to the modification of the microscopic potential realization resulting from thermal recycling of the structure.
BREAKDOWN OF THE QUANTUM HALL EFFECTS IN HOLE SYSTEMS AT HIGH INDUCED CURRENTS
Authors: GETHING J. D. , MATTHEWS A. J. , USHER A. , PORTNOI M. E. , KAVOKIN K. V. , HENINI M.
Published: April 2005

The magnetisation of two dimensional hole systems in the quantum Hall regime has been studied using a highly-sensitive torsion balance magnetometer. In a time varying magnetic field eddy currents are induced which become large around integer and fractional filling factors where ρxx takes a very low value. The sweep rate and temperature dependence of these induced currents are in good agreement with the model of quantum Hall effect breakdown proposed recently by Matthews et al. This model also allows comparison between the energy gap at different filling factors and so provides a measurement of the fractional quantum Hall effect energy gap, Δ1/3, and the spin split energy gap, g*μ B B.
SUPPRESSION OF BACKSCATTERING IN QUANTUM HALL NARROW CHANNEL UNDER TRANSVERSALLY MODULATED MAGNETIC FIELD
Authors: HARA MASAHIRO , ENDO AKIRA , KATSUMOTO SHINGO , IYE YASUHIRO
Published: April 2005

We have studied transport in a narrow Hall bar subjected to a transversally modulated magnetic field in quantum Hall regime. Landau level spatially varies across the channel and suppresses back scattering between oppositely directed edge channels. The resistance suppressed by the "magnetic barrier" recovers with increasing temperature, showing thermally activated temperature dependence.
MAGNETIC FIELD ENHANCED BACKSCATTERING OF FOCUSED ELECTRONS IN MESOSCOPIC METALLIC BRIDGES
Authors: DE JONGE J. , ZEITLER U. , MAAN J. C. , MIKHAILOV G. M. , APARSHINA L. I. , CHERNYKH A. V. , MALIKOV I. V. , VINNICHENKO V. Y.
Published: April 2005

We have observed an increase in the longitudinal magnetoresistance of mesoscopic tungsten bridges at low temperatures. We propose this effect to be caused by backscattering of electrons through spiralling orbits with radius smaller than the film thickness. When tilting the field direction slightly away from the bridge-axis, additional surface scattering leads to an abrupt destruction of this backscattering.
HYSTERESIS IN THE QUANTUM HALL REGIMES IN ELECTRON DOUBLE-QUANTUM-WELL STRUCTURES
Authors: PAN W. , RENO J. L. , SIMMONS J. A.
Published: April 2005

We present in this paper the experimental results of transport hysteresis in an extremely imbalanced electron double-quantum-well (DQW) structure. The ratio of the top layer density (ntop) to bottom layer density (nbot) is continuously tuned by applying voltage to a front gate. Under a condition when the top layer is nearly depleted (ntop~3×1010 cm -2) while the bottom layer remains at nbot=1.9×1011 cm -2, the hysteresis is absent in the B sweeps as long as the total Landau level filling ν<1 and the 2D electron systems are in the fractional quantum Hall effect regime. Surprisingly, a large hysteresis is observed during the gate sweeps at the same values of B and ntop. We attribute this unexpected hysteresis to the formation of an insulating state, probably a weakly pinned Wigner solid state, in the top layer.
HIGH-FIELD MAGNETOTRANSPORT STUDIES OF FERROMAGNETIC GaAs/Mn DIGITAL ALLOYS
Authors: KIM G. B. , NA M. , ACBAS G. , MCCOMBE B. D. , WANG S. , CHEON M. , LUO H. , LIU X. , SASAKI Y. , FURDYNA J. K.
Published: April 2005

Magnetotransport properties of ferromagnetic GaAs / Mn digital alloys have been investigated in fields up to 33 T. A series of four GaAs / Mn digital alloys with different Mn coverages (0.15 ML - 0.5 ML) at fixed GaAs spacer thickness (9 ML), with Curie temperatures, TC, between 20 and 40 K shows hopping conduction behavior in the zero-field sheet resistance below TC. Analysis of the high field magnetotransport measurements on these samples reveals hole densities between 0.45×1013 and 1.8×1013 cm -2/ Mn layer at 5 K. In contrast, a GaAs / Mn digital alloy with slightly different parameters (0.5 ML Mn and 14 ML GaAs spacer layers) and growth conditions shows essentially metallic behavior and much higher TC (60 K). The zero-field sheet resistance, although decreasing weakly with T at low temperatures, cannot be fit by a hopping expression. From analysis of Shubnikov-de Haas oscillations observed in this sample, an effective mass of ≈0.31m0 was determined, close to the heavy hole mass of GaAs . The hole density extracted from fits to RHall at high fields is comparable to that of the insulating GaAs / Ma digital alloys at the same Mn coverage. This suggests that the increased metallicity is the most important factor in significantly enhancing TC.
EFFECT OF THE VOIGT MAGNETIC FIELD ON THE EXCITON COMPLEXES IN ZnSe/BeTe TYPE-II SINGLE QUANTUM WELLS
Authors: YAMAMOTO HIROAKI , JI ZIWU , MINO HIROFUMI , AKIMOTO RYOICHI , TAKEYAMA SHOJIRO
Published: April 2005

We have performed the magneto-photoluminescence (PL) measurements on ZnSe / BeTe quantum well (QW) structures with a type-II band alignment in a Voigt configuration. The PL spectra were composed of two components. The lower energy PL peak energy shows red-shifts applying magnetic field. A model of the energy dispersion shift of the spatially indirect exciton complexes probably explains these results.
HIGH FIELD RESONANT TUNING OF THE NUCLEAR SPIN-QUBIT RELAXATION RATE IN 2DES WITH MAGNETIC IMPURITIES: STRONG SCATTERING LIMIT
Authors: DAHAN PINCHAS , VAGNER ISRAEL
Published: April 2005

The strong scattering limit of the magnetic field dependence of the local phonon-assisted nuclear spin relaxation rate, (NSRR), in two dimensional electron systems, (2DES) with magnetic impurities is calculated. It is shown that the NSRR can be tuned resonantly, by external magnetic field, due to the possibility of matching the electron Zeeman splitting with the energy spacing between the localized vibrational modes created by the lattice distortion around the impurity. This new resonance phenomenon could be used to manipulate, with high precision, the relaxation and decoherence times of nuclear spin based quantum information processing devices.
CRITICAL REVIEW OF THE ARMITAGE AND BROSS SEQUENTIAL PROCEDURES IN CLINICAL REHABILITATION TRIALS
Authors: Jones Troy , Hussein Abdulkadir A. , Kumar Shrawan
Published: April 2005

The use of sequential analysis in clinical rehabilitation research allows a spectrum of analyses in the comparison of two or more treatment protocols. Researchers in rehabilitation medicine are increasingly making use of sequential designs in their clinical investigations. This review serves to highlight the optimal use of the classical sequential designs presented by Armitage and Bross in the mid-twentieth century. A discussion of the limitations of this most basic sequential analysis is presented for the information of clinical researchers considering this study design. Examples of the use of classical and group sequential designs addressing both continuous and dichotomous outcomes are provided, and the advantages and disadvantages of classical and group sequential procedures as compared to fixed sample designs are illustrated with rehabilitation examples. As little literature has been published regarding the application of sequential analysis in clinical rehabilitation trials, clinical pharmacological, and medical trials in addition to medical statistical sources were used in this review.
HOUSEHOLD-USE VERSUS BUSINESS-USE DEMAND DIFFUSION OF TELEPHONE AND INTERNET ACCESS SERVICE IN KOREA
Authors: KIM MOON-SOO
Published: April 2005

It is well known that the diffusion of the Internet over society has been faster than that of the traditional telecommunication service such as the telephone. There are some differences between the demand diffusion patterns of telephone services and the Internet as well as among the demand attributes, thus we focus on these differences. With each service, demand attributes comprise of business-use and household-use. In particular, Loglet analysis is used for comparing the diffusion pattern demand-attributes for the services. Firstly, from the analysis, during the overall reference period, the diffusion rate of the Internet is larger than that of telephone. Secondly, the gap between the diffusion rates of household-use and business-use in the Internet is much larger than it is for the telephone. Thirdly, the estimated potential demands of the Internet household-use are surprisingly similar to the present number of telephone users. We also examine country-specific factors underlying the diffusion of Internet access service in Korea.
Petrology and geochemistry of the Shuiquangou syenitic complex, northern margin of the North China Craton
Authors: Jiang Neng
Published: April 2005

The Palaeozoic Shuiquangou complex is a major syenitic intrusion along the northern margin of the North China Craton that hosts a number of gold deposits. Despite the heterogeneity of the complex in terms of texture and modal mineralogy, mineral compositions, whole-rock chemistry as well as radiogenic isotope compositions show a well-constrained magmatic evolutionary trend. The whole-rock major element and REE trends are broadly consistent with fractional crystallization dominated by clinopyroxene, amphibole and accessory minerals. Initial Nd–Sr isotopic compositions suggest that the parent magmas to the complex were ultimately derived from an enriched mantle with relatively high initial
87
Sr/
86
Sr ratios and negative ϵ
Nd
values. The enrichment of the mantle source was probably inherited from an older lithospheric mantle beneath the North China Craton. Sr isotopic data indicate that the Rb–Sr system was disturbed by later alteration processes, whereas Nd isotopes are essentially unaffected and exhibit a broad trend consistent with simultaneous fractional crystallization and country-rock assimilation (AFC). Quantitative modelling indicates that a very high bulk distribution coefficient for Nd and low ratios of assimilation to crystallization are needed to produce the observed Nd isotope evolutionary trend.
Grampian and late Grenville events recorded by mineral geochronology near a basement–cover contact in north Mayo, Ireland
Authors: Daly J. Stephen , Flowerdew Michael J.
Published: April 2005

The Palaeoproterozoic to early Neoproterozoic Annagh Gneiss Complex structurally underlies the Dalradian sequence in north Mayo, Ireland, and has been proposed as the depositional basement to Dalradian metasediments. The Annagh Gneiss Complex was deformed, metamorphosed and migmatized during the Grenville Orogeny and later reworked under amphibolite-facies conditions. This paper focuses on the timing of the post-Grenville events and particularly on the possible presence of post-Grenville, pre-Grampian deformation that could be attributed to the Knoydartian Orogeny. Seven U–Pb titanite analyses from Annagh Gneiss Complex gneisses have a weighted mean
207
Pb/
206
Pb age of 963 ± 8 Ma, which dates cooling after the main Grenville metamorphism. Locally, a later phase of titanite growth at 943 ± 8 Ma post-dates the last phase of Grenville deformation. The weak discordance of the titanite data suggests that post-Grenville events had little effect on the U–Pb system in titanite. If the discordance was caused by a tectonic event, this is likely to have occurred during the early Ordovician Grampian Orogeny rather than in the Neoproterozoic. Within the Annagh Gneiss Complex, cross-cutting metadolerites provide a structural marker allowing post-Grenville deformation to be distinguished. In contrast, correlative metadolerites cutting the adjacent Dalradian metasediments share all Grampian deformation events affecting their host. Ar–Ar hornblende ages from the post-Grenville metadolerites indicate that reworking of the Annagh Gneiss Complex and the first episodes of Dalradian deformation occurred during the Grampian Orogeny in this part of Ireland. One sample yields a 475 ± 4 Ma Ar–Ar plateau age, which is interpreted to date Grampian deformation. Younger Ar–Ar hornblende and Rb–Sr mica ages record post-Grampian cooling. Neither field nor isotopic evidence for the Knoydartian Orogeny has been found in this part of Ireland.
Bolus transit patterns in healthy subjects: a study using simultaneous impedance monitoring, videoesophagram, and esophageal manometry
Authors: Imam Hala , Shay Steven , Ali Aman , Baker Mark
Published: April 2005

Impedance monitoring (Imp) measures bolus transit. Combining Imp with manometry (EM) allows the effect of contractile patterns on transit to be assessed. The objective of this study is to identify bolus transit patterns in normal subjects, correlate Imp findings with the gold standard barium esophagram (Ba), and compare bolus transit with concomitant EM findings. Simultaneous Ba-Imp-EM was performed for 2 min in 15 normal volunteers (women, 11; age, 43 yr). Combined impedance-pressure sites were 5, 10, 15, 20 cm above the lower esophageal sphincter (LES). Boluses (10 ml) of 45% barium mixed with 0.9% NaCl were swallowed at ≥20-s intervals (5–6 swallows/subject). Imp and Ba showed three bolus transit patterns, and the two methods were in agreement on the pattern type in 97% (83/86) of swallows. Normal bolus transit was found in 73% (61/83), and each had normal peristalsis and contraction amplitude. Stasis in the proximal esophagus occurred in 7 of 83 swallows despite normal manometric parameters in 4 of 7 swallows. Retrograde escape of a residue of incompletely cleared bolus from just above the LES to the site 5 cm above occurred in 14 of 83 swallows. Retrograde escape was triggered by the next swallow, occurred despite normal manometric parameters, and did not occur if the swallow interval was >30 s. In 55% (47/86) of swallows, air accumulated in the distal esophagus and persisted there for a mean of 3.6 s until cleared into the stomach. We conclude that impedance monitoring is a valid transit test and describe bolus transit patterns in normal subjects for comparison with patients with esophageal motility disorders.
Pulmonary Hypertension in a GTP-Cyclohydrolase 1–Deficient Mouse
Authors: Nandi Manasi , Miller Alyson , Stidwill Raymond , Jacques Thomas S. , Lam Amanda A.J. , Haworth Sheila , Heales Simon , Vallance Patrick
Published: April 2005

Background—

GTP-cyclohydrolase 1 (GTP-CH1) catalyzes the first step for the de novo production of tetrahydrobiopterin (BH
4
), a cofactor for nitric oxide synthase (NOS). The hyperphenylalaninemic mutant mouse (hph-1) displays a 90% reduction in GTP-CH1 activity. Reduced BH
4
decreases NOS activity and may lead to endothelial dysfunction, and there is increasing evidence that a dysfunction of the NOS pathway may be implicated in pulmonary hypertension. The aim of the study was to investigate whether reduced BH
4
in the hph-1 mouse results in a pulmonary hypertensive phenotype.

Methods and Results—

Morphological characterization of the heart, lung, and kidney and measurements of systemic and right ventricular blood pressures were performed in both hph-1 and wild-type mice. BH
4
and NO
x
levels were also measured. Hph-1 mice had significantly lower NO
x
and BH
4
levels, consistent with previous findings. Both morphological and in vivo data were indicative of a pulmonary but not systemic hypertensive phenotype. We observed increased right ventricle–left ventricle plus septum ratios attributable only to an increase in right ventricular mass, increased smooth muscle medial area in pulmonary resistance vessels, and significantly higher right ventricular pressures in vivo. There were no significant differences between left ventricular masses and systemic pressures, and there was no observed evidence of systemic hypertension in kidney sections between wild-type and hph-1.

Conclusions—

This study demonstrates that mice deficient in GTP-CH1/BH
4
display a pulmonary hypertensive but not systemic hypertensive phenotype.
Global Biomass Variation and Its Geodynamic Effects: 1982–98
Authors: Rodell M. , Chao B. F. , Au A. Y. , Kimball J. S. , McDonald K. C.
Published: April 2005

Redistribution of mass near Earth’s surface alters its rotation, gravity field, and geocenter location. Advanced techniques for measuring these geodetic variations now exist, but the ability to attribute the observed modes to individual Earth system processes has been hampered by a shortage of reliable global data on such processes, especially hydrospheric processes. To address one aspect of this deficiency, 17 yr of monthly, global maps of vegetation biomass were produced by applying field-based relationships to satellite-derived vegetation type and leaf area index. The seasonal variability of biomass was estimated to be as large as 5 kg m−2. Of this amount, approximately 4 kg m−2 is due to vegetation water storage variations. The time series of maps was used to compute geodetic anomalies, which were then compared with existing geodetic observations as well as the estimated measurement sensitivity of the Gravity Recovery and Climate Experiment (GRACE). For gravity, the seasonal amplitude of biomass variations may be just within GRACE’s limits of detectability, but it is still an order of magnitude smaller than current observation uncertainty using the satellite-laser-ranging technique. The contribution of total biomass variations to seasonal polar motion amplitude is detectable in today’s measurement, but it is obscured by contributions from various other sources, some of which are two orders of magnitude larger. The influence on the length of day is below current limits of detectability. Although the nonseasonal geodynamic signals show clear interannual variability, they are too small to be detected.
Indian Monsoon Onset and the Americas Midsummer Drought: Out-of-Equilibrium Responses to Smooth Seasonal Forcing
Authors: Mapes Brian E. , Liu Ping , Buenning Nikolaus
Published: April 2005

Two dominant high-frequency features of Northern Hemisphere summer climatology are examined in an atmosphere–land general circulation model (AGCM): the sudden onset of rains in south Asia, and the midsummer rainfall minimum in the tropical Americas. A control simulation succeeds in capturing these observed features fairly well. A slowed-calendar experiment is performed, to see whether these features are close to equilibrium with seasonally evolving forcings (orbital geometry and SST). The results indicate that some lag (disequilbrium) within the AGCM delays south Asian onset by about a month, from May in the experiment when seasonal forcing evolves extremely slowly to June in the normal, full-speed seasonal cycle. Disequilibrium also acts to delay and limit the amplitude of the Americas midsummer drought, and the associated intrusion of the Atlantic subtropical high into the Intra-Americas Seas’ region. It is hypothesized that early summer (centered on the solstice) temperature over mid- and high-latitude continents, which differs greatly between experiment and control, drives the low-latitude rainfall differences. A more mysterious pole-to-pole, annual-mean, zonal wave-1 difference is also found in the slowed-calendar experiment.
New Vibrio cholerae O1 Biotype ElTor bacteriophages
Authors: Sen Anindito , Ghosh Amar N
Published: April 2005

We report the presence of three new O1 ElTor vibriophages named AS1, AS2 and AS3, isolated from the sewage and pond waters of the outskirts of Kolkata. A few phages, named AS4, with hexagonal heads and abnormally long tails with typical curly projections were also found in the water samples.
Is obesity a risk factor for low back pain? An example of using the evidence to answer a clinical question
Authors: Mirtz Timothy A , Greene Leon
Published: April 2005

Background

Obesity as a causal factor for low back pain has been controversial with no definitive answer to this date. The objective of this study was to determine whether obesity is associated with low back pain. In addition this paper aims to provide a step-by-step guide for chiropractors and osteopaths on how to ask and answer a clinical question using the literature.

Methods

A literature review using the MEDLINE search engine using the keywords "obesity", "low back pain", "body mass index" "BMI" and "osteoarthritis" from years 1990 to 2004 was utilised. The method employed is similar to that utilised by evidence-based practice advocates.

Results

The available data at this time is controversial with no clear-cut evidence connecting low back pain with obesity.

Conclusion

There is a lack of a clear dose-response relationship between body mass index (BMI) and low back pain. Further, studies on the relationship between obesity and related lumbar osteoarthritis, knee pain, and disc herniation are also problematic.There is little doubt that future studies with controlled variables are needed to determine the existence of an unambiguous link, if any.
Vestibular Cortical Area in the Periarcuate Cortex
Authors: SUGIUCHI YURIKO , IZAWA YOSHIKO , EBATA SHIGETO , SHINODA YOSHIKAZKU
Published: April 2005

Abstract: Vestibular input to the periarcuate cortex in the Japanese monkey was examined by analyzing laminar field potentials evoked by electrical stimulation of the vestibular nerve. Vestibular‐evoked potentials consisted of early‐positive and late‐negative potentials and early‐negative and late‐positive potentials in the superficial and deep layers of the cortex, respectively. They were distributed bilaterally in the periarcuate cortex around the junction of the spur and the arcuate sulcus. This vestibular‐projecting area corresponded to the periarcuate area where retrogradely‐labeled corticovestibular neurons were distributed after the injection of a tracer into the vestibular nuclei. Comparison of the vestibular‐projection area with the distribution of smooth pursuit‐related neurons in the same monkey revealed that such neurons existed in the vestibular‐projecting area of the periarcuate cortex.
Context‐Specific Adaptation of Saccade Gain Is Enhanced with Rest Intervals Between Changes in Context State
Authors: SHELHAMER MARK , ABOUKHALIL ANTON , CLENDANIEL RICHARD
Published: April 2005

Abstract: Dual‐state adaptation of motor responses has been known for some time. A more recent development is a form of dual‐state adaptation known as “context‐specific adaptation,” which was explored through the use of saccade gain adaptation. In this model, two different adapted saccade gains are associated with two different states of a context cue, and the gain switches between the two adapted states when the context cue changes state. Such adaptation is imposed by alternating context/adaptation states over the course of an adaptation session. Here, vertical eye position as a context cue for adaptation of horizontal saccade gain is used: gain increase is induced with the eyes up 10°, and gain decrease with the eyes down 10°. This context cue is not very effective: there is interference between context/adaptation conditions such that gain‐decrease adaptation with eyes down transfers to the eyes‐up (gain‐increase) context. It was hypothesized that the juxtaposition in time of the alternating adaptation states exacerbated this interference. In order to test this, one‐minute rest breaks were inserted between each change in context/adaptation state. The resulting context‐specific adaptation improved dramatically: gain‐increase and gain‐decrease adaptations were more rapid and more complete. This resembles consolidation of motor learning, which, however, occurs over much longer time spans (hours rather than minutes). Thus, the results may reflect the operation of a novel “short‐term” motor consolidation process.
Readout of Higher‐Level Processing in the Discharge of Superior Colliculus Neurons
Authors: KELLER EDWARD L. , LEE KYOUNG‐MIN , MCPEEK ROBERT M.
Published: April 2005

Abstract: The discharge of neurons in the deeper layers of the superior colliculus (SC) was studied while monkeys performed two visual discrimination tasks that required different amounts of cognitive processing. In a search paradigm the animal's task was to saccade to the location of an odd‐colored stimulus located in an array of distractors of uniform color (pop‐out visual search). The visual stimuli remained on the screen as the discrimination process distinguished target from distractors. In a choice response task the color of a central cue signaled which stimulus from a previously presented array of colored stimuli was to be the target of a saccade. The stimulus array was turned off well before the central cue was presented. Most neurons showed activity aligned on both the visual input and the motor response in single‐target tasks. Many of these same neurons showed additional discharge that was correlated with the required higher‐level decision processes in both of these more natural visual tasks. In the case of pop‐out search the SC has been shown to be functionally involved in the decision processes. The cue‐aligned activity in SC in the choice response task is surprising because no transient visual stimulus appeared in the response field of the neuron.
Synaptic Inputs and Their Pathways from Fixation and Saccade Zones of the Superior Colliculus to Inhibitory Burst Neurons and Pause Neurons
Authors: TAKAHASHI MAYU , SUGIUCHI YURIKO , IZAWA YOSHIKO , SHINODA YOSHIKAZU
Published: April 2005

Abstract: The caudal part of the superior colliculus (SC) plays an important role in the generation of saccades, whereas the rostral part of the SC is considered to be involved in visual fixation. The present study was performed to determine neural connections from the rostral and caudal parts of the SC to inhibitory burst neurons (IBNs) and pause neurons (PNs) in the nucleus raphe interpositus in the anesthetized cat, and to reveal the functional role of the rostral SC on eye movements. The intracellular potentials from IBNs and PNs were recorded, and the effects of stimulation of the SC on these neurons were analyzed. The results show that IBNs receive monosynaptic excitation from the contralateral caudal SC, and disynaptic inhibition from the ipsilateral caudal SC via contralateral IBNs. In addition, IBNs receive disynaptic inhibition from the rostral part of the SC on either side via inhibitory interneurons other than IBNs. Intracellular recording from PNs revealed that they receive convergent excitation from the rostral parts of the bilateral superior colliculi and that the rostral SC inhibits IBNs on both sides via PNs. The neural connections determined in this study support the functional independence of the rostral SC and are consistent with the notion that the “fixation zone” is localized in the rostral SC. These results show that the fixation zone in the rostral SC may suppress the initiation of bilateral saccades via pause neurons.
Initiation and Suppression of Saccades by the Frontal Eye Field in the Monkey
Authors: IZAWA YOSHIKO , SUZUKI HISAO , SHINODA YOSHIKAZU
Published: April 2005

Abstract: After a saccadic eye movement occurs to an interesting object appearing in the visual field, visual fixation holds its image on the fovea and suppresses saccades to other objects appearing in the visual field. To understand the neural mechanism of visual fixation, the effects of electrical stimulation of the frontal eye field (FEF) on the generation of electrically evoked saccades (Esacs) and the suppression of saccades in trained monkeys were investigated. When the properties of the electrically evoked suppression of visually guided (Vsacs) and memory‐guided saccades (Msacs) were examined, two types of suppression were found. Stimulation of a wide area of the FEF suppressed only ipsiversive Vsacs and Msacs at stimulus intensities lower than those for eliciting Esacs, whereas stimulation of a localized area of the FEF suppressed the initiation of both Vsacs and Msacs in any direction during and ∼50 ms after stimulation. However, neither stimulation affected the vector of these saccades. The thresholds for suppression were usually less than 50 μA. The most effective stimulation timing for the suppression of ipsiversive and contraversive Vsacs was ∼40 to 50 ms before saccade onset. Therefore, suppression occurred in the efferent pathway for Vsacs at the premotor rather than the motoneuronal level, most likely in the superior colliculus and/or the paramedian pontine reticular formation. The results suggest that the suppression in the FEF may play a role in maintaining visual fixation by suppressing the generation of saccades.