bluuebunny/crossref_metadata_2025 huggingface dataset:
Fluorescence quenching by excimer formation: Quenching constant approximations for excimer formation-dissociation by classical potential models
Authors: Naumann Wolfgang
Published: August 2005

Fluorescence quenching by excimer formation is studied on the assumption that the excimer formation and dissociation can be modeled as overdamped motion in an attractive potential (classical potential models). An approach to the zeroth-order, concentration-independent quenching constants is proposed which starts from a mean reaction-time ansatz and reduces the calculation essentially to the solution of the eigenvalue problem for the Smoluchowski operator which describes the excimer equilibration. For a square-well potential model it is shown that a quenching constant expansion in terms of relaxation modes, truncated at the kinetic level, gives a satisfactory approximation of the recently obtained exact zeroth-order result under defined conditions. It is demonstrated how this two-mode approach can be applied for a quenching constant estimation if the excimer formation and dissociation are modeled by more realistic interaction potentials, as for instance, Morse- or Gaussian-type ones.
On the nature of the Møller-Plesset critical point
Authors: Sergeev Alexey V. , Goodson David Z. , Wheeler Steven E. , Allen Wesley D.
Published: August 2005

It has been suggested [F. H. Stillinger, J. Chem. Phys. 112, 9711 (2000)] that the convergence or divergence of Møller-Plesset perturbation theory is determined by a critical point at a negative value of the perturbation parameter z at which an electron cluster dissociates from the nuclei. This conjecture is examined using configuration-interaction computations as a function of z and using a quadratic approximant analysis of the high-order perturbation series. Results are presented for the He, Ne, and Ar atoms and the hydrogen fluoride molecule. The original theoretical analysis used the true Hamiltonian without the approximation of a finite basis set. In practice, the singularity structure depends strongly on the choice of basis set. Standard basis sets cannot model dissociation to an electron cluster, but if the basis includes diffuse functions then it can model another critical point corresponding to complete dissociation of all the valence electrons. This point is farther from the origin of the z plane than is the critical point for the electron cluster, but it is still close enough to cause divergence of the perturbation series. For the hydrogen fluoride molecule a critical point is present even without diffuse functions. The basis functions centered on the H atom are far enough from the F atom to model the escape of electrons away from the fluorine end of the molecule. For the Ar atom a critical point for a one-electron ionization, which was not previously predicted, seems to be present at a positive value of the perturbation parameter. Implications of the existence of critical points for quantum-chemical applications are discussed.
Multidimensional time-dependent discrete variable representations in multiconfiguration Hartree calculations
Authors: van Harrevelt Rob , Manthe Uwe
Published: August 2005

In the multiconfiguration time-dependent Hartree (MCTDH) approach, the wave function is expanded in time-dependent basis functions, called single-particle functions, to increase the efficiency of the wave-packet propagation. The correlation discrete variable representation (CDVR) approach, which is based on a time-dependent discrete variable representation (DVR), can be employed to evaluate matrix elements of the potential energy. The efficiency of the MCTDH method can be further enhanced by using multidimensional single-particle functions. However, up to now the CDVR approach could not be used in MCTDH calculations employing multidimensional single-particle functions, since this would require a general multidimensional non-direct-product DVR scheme. Recently, Dawes and Carrington presented a practical scheme to implement general non-direct-product multidimensional DVRs [R. Dawes and T. Carrington, Jr., J. Chem. Phys. 121, 726 (2004)]. The present work utilizes their scheme in the MCTDH/CDVR approach. The accuracy is tested using the photodissociation of NOCl as example. The results show that the CDVR scheme based on multidimensional time-dependent DVRs allows for an accurate evaluation of the potential in MCTDH calculations with multidimensional single-particle functions.
Light-scattering form factors of asymmetric particle dimers from heteroaggregation experiments
Authors: Galletto Paolo , Lin Wei , Mishchenko Michael I. , Borkovec Michal
Published: August 2005

Measurements of form factors of asymmetric particle dimers composed of oppositely charged polystyrene latex particles are presented. These measurements are based on time-resolved static and dynamic light scattering on dilute aggregating aqueous suspensions. The experimental form factors are compared with independent calculations based on the superposition T-matrix method and Rayleigh-Debye-Gans (RDG) approximation. While the RDG approximation is found to be reliable only up to particle diameters of about 250 nm, the superposition T-matrix method is very accurate for all types of dimers investigated. The present results show clearly the appropriateness of the superposition T-matrix method to estimate the optical properties of colloidal particles in the micrometer range reliably.
Molecular dynamics simulations of matrix deposition. III. Site structure analysis for porphycene in argon and xenon
Authors: Kyrychenko Alexander , Waluk Jacek
Published: August 2005

Porphycene (1) and porphyrin (2), two constitutional isomers, reveal completely different electronic spectral patterns in argon and xenon matrices. For the former the spectra recorded in the two solidified gases resemble each other, whereas for the latter they are completely different. This difference can be rationalized by molecular-dynamics simulations of the structure of the microenvironment carried out for the two chromophores embedded in argon and xenon hosts. For 1, the structure of the main substitutional site is the same for Ar and Xe and consists of a hexagonal cavity obtained by removing seven host atoms from the {111} crystallographic plane. An analogous structure is obtained for 2 in xenon. However, in argon the porphyrin chromophore environment is shared between several different sites, with the number of replaced host atoms ranging from seven to ten. These results demonstrate that a relatively minor structural alternation may lead to major changes in the spectral pattern of molecules embedded in rare-gas cryogenic matrices.
NMR measurements of hyperpolarized He3 gas diffusion in high porosity silica aerogels
Authors: Tastevin Geneviève , Nacher Pierre-Jean
Published: August 2005

Hyperpolarized He3 is used to nondestructively probe by NMR the structure of custom-made and commercial silica aerogels (97% and 98.5% porous). Large spin-echo signals are obtained at room temperature and very low magnetic field (2mT) even with small amounts of gas. Attenuation induced by applied field gradients results from the combined effects of gas diffusion and confinement by the porous medium on atomic motion. Nitrogen is used as a buffer gas to reach equivalent He3 pressures ranging from 5mbarsto3.5bars. The observed pressure dependence suggests a nonuniform structure of the aerogels on length scales up to tens of micrometers. A description by broad phenomenological distributions of mean free paths is proposed, and quantitatively discussed by comparison to numerical calculations. The investigated aerogel samples exhibit different effective diffusion characteristics despite comparable nominal porosities.
Bounds on localizable information via semidefinite programming
Authors: Synak-Radtke Barbara , Horodecki Karol , Horodecki Michał
Published: August 2005

We investigate the so-called localizable information of bipartite states and a parallel notion of information deficit. Localizable information is defined as the amount of information that can be concentrated by means of classical communication and local operations where only maximally mixed states can be added for free. The information deficit is defined as difference between total information contents of the state and localizable information. We consider a larger class of operations, the so-called PPT operations, which in addition preserve maximally mixed state (PPT-PMM operations). We formulate the related optimization problem as a semidefinite program with suitable constraints. We then provide bound for fidelity of transition of a given state into product pure state on Hilbert space of dimension d. This allows to obtain a general upper bound for localizable information (and also for information deficit). We calculated the bounds exactly for Werner states and isotropic states in any dimension. Surprisingly it turns out that related bounds for information deficit are equal to relative entropy of entanglement (in the case of Werner states, regularized one). We compare the upper bounds with lower bounds based on simple protocol of localization of information.
Direct studies of domain switching dynamics in thin film ferroelectric capacitors
Authors: Gruverman A. , Rodriguez B. J. , Dehoff C. , Waldrep J. D. , Kingon A. I. , Nemanich R. J. , Cross J. S.
Published: August 2005

An experimental approach for direct studies of the polarization reversal mechanism in thin film ferroelectric capacitors based on piezoresponse force microscopy (PFM) in conjunction with pulse switching capabilities is presented. Instant domain configurations developing in a 3×3μm2 capacitor at different stages of the polarization reversal process have been registered using step-by-step switching and subsequent PFM imaging. The developed approach allows direct comparison of experimentally measured microscopic switching behavior with parameters used by phenomenological switching models. It has been found that in the low field regime (just above the threshold value) used in the present study, the mechanism of polarization reversal changes during the switching cycle from the initial nucleation-dominated process to the lateral domain expansion at the later stages. The classical nucleation model of Kolmogorov–Avrami–Ishibashi (KAI) provides reasonable approximation for the nucleation-dominated stage of switching but is inapplicable to the slow switching stage. It has been suggested that the switching dynamics can be approximated by averaging the KAI model over a broad distribution of switching times.
Thermal activation effect on spin transfer switching in magnetic tunnel junctions
Authors: Higo Y. , Yamane K. , Ohba K. , Narisawa H. , Bessho K. , Hosomi M. , Kano H.
Published: August 2005

A calculation of the intrinsic spin transfer switching current Ic0 is realized in the magnetic tunnel junctions (MTJs). Ic0 is determined by the distribution of Ic in repeated measurements, assuming the linear decrease of the thermal stability by increasing the spin-polarized current. The spin transfer torque is found to be proportional to η(I)I with the applied current I and I-dependent spin polarization η(I). Even in case that I is limited less than Ic due to the tunnel barrier breakdown, Ic0 is calculated with an assisting external magnetic field and making better use of the magnetic phase diagram. In our MTJs, the average intrinsic switching current density was 6.4MA∕cm2.
Atomic resolution on MgO(001) by atomic force microscopy using a double quartz tuning fork sensor at low-temperature and ultrahigh vacuum
Authors: Heyde M. , Sterrer M. , Rust H.-P. , Freund H.-J.
Published: August 2005

Atomic resolution with a double quartz tuning fork sensor for low-temperature ultrahigh vacuum atomic force and scanning tunneling microscopy is presented. The new features of the force sensor assembly are discussed. Atomically resolved images of MgO on Ag(001) have been obtained. Images acquired in the attractive and the repulsive regimes controlled to a constant frequency shift are shown, revealing contrast changes.
Magnetron priming by multiple cathodes
Authors: Jones M. C. , Neculaes V. B. , Lau Y. Y. , Gilgenbach R. M. , White W. M. , Hoff B. W. , Jordan N. M.
Published: August 2005

A relativistic magnetron priming technique using multiple cathodes is simulated with a three-dimensional, fully electromagnetic, particle-in-cell code. This technique is based on electron emission from N∕2 individual cathodes in an N-cavity magnetron to prime the π mode. In the case of the six-cavity relativistic magnetron, π-mode start-oscillation times are reduced up to a factor of 4, and mode competition is suppressed. Most significantly, the highest microwave field power is observed by utilizing three cathodes compared to other recently explored priming techniques.
Isothermal relaxation of field-biased barium stannate titanate
Authors: Wei Xiaoyong , Jin Li , Yao Xi
Published: August 2005

The isothermal time dependences of the dielectric constant and the discharging current of barium stannate titanate ceramics after application or removal of a step field were investigated in both ferroelectric and paraelectric temperature regions. The experimental results exhibited a substantial difference for these two phases. For the ferroelectric phase, the relaxation of the dielectric constant is weak and the discharging current obeys Hammon’s model. While for the paraelectric phase, the relaxation is relatively strong and the discharging current obeys the complex exponential decay model. The relaxation of the field-induced piezoelectric resonance indicated the first relaxation observed in a paraelectric phase sample corresponding to homocharges. The authors proposed that the transportation of homocharges is the microscopic origin of the strong relaxation observed in the paraelectric phase.
Bendable GaAs metal-semiconductor field-effect transistors formed with printed GaAs wire arrays on plastic substrates
Authors: Sun Yugang , Kim Seiyon , Adesida Ilesanmi , Rogers John A.
Published: August 2005

Micro/nanowires of GaAs with integrated ohmic contacts have been prepared from bulk wafers by metal deposition and patterning, high-temperature annealing, and anisotropic chemical etching. These wires provide a unique type of material for high-performance devices that can be built directly on a wide range of unusual device substrates, such as plastic or paper. In particular, transfer printing organized arrays of these wires at low temperatures onto plastic substrates yield high-quality bendable metal-semiconductor field-effect transistors. Electrical and mechanical characterization of devices on poly(ethylene terephthalate) illustrates the level of performance that can be achieved. These results indicate promise for this approach to high-speed flexible circuits for emerging applications in consumer and military electronic systems.
A comparison of field-based and modelled reflectance spectra from damaged Pinus radiata foliage
Authors: Coops Nicholas C. , Stone Christine
Published: August 2005

Accurate and cost-effective monitoring of the health and condition of Australian Pinus radiata D.Don plantations is crucial to predicting the impact of damaging agents on wood yield and, where appropriate, targeting timely intervention. Stressful agents can induce changes in the biochemical, physiological and structural integrity of pine needles and subsequently reduce tree growth and ultimately cause plant death. Three important stressful agents occurring within Australian P. radiata plantations are the aphid Essigella californica, soil nitrogen deficiency and Sphaeropsis sapinea, a fungal pathogen. Within a study site in southern New South Wales, needles were sampled from crowns exhibiting key symptoms at three levels of crown severity. Needle level spectra were measured with a field spectroradiometer and foliage samples taken to extract needle chlorophyll a and b and to determine needle moisture content. A radiative transfer model (LIBERTY) was also used to estimate theoretical needle reflectance, given changes in two of its five input parameters (needle chlorophyll and moisture content). Two specific questions were posed. First, given that most spectral indices are based on a reference or stable wavelength as well as sensitive wavelengths, what is the most effective suite of stable wavelengths for predicting of needle chlorophyll and moisture? Second, which published spectral indices best discriminated the three categories of crown-damage severity for each damaging agent? Analysis of needle samples indicated that the needles affected by E. californica were the least chlorotic compared with the other damaging agents. For all damaging agents, needles showed an increase in reflectance with a lowering of chlorophyll content in the visible region (400–700 nm), associated with increasing severity. Changes in the shape of the spectral curve in the red-edge region of the electromagnetic spectrum were minor for E. californica-affected and nitrogen-deficient needles; however, changes were significant when comparing the S. sapinea severity classes. Correlations with published vegetation indices indicated that needle chlorophyll content was most highly correlated with a number of the recently proposed indices, including the structurally insensitive simple ratio. In general, the best results were obtained with 705 nm as the chlorophyll sensitive wavelength and either 750 or 445 nm as the insensitive wavelengths to account for needle reflectance and surface properties. By varying two of the input parameters of the LIBERTY model, the estimated spectra generally matched the trends and magnitude of actual spectra. This suggests that the application of radiative transfer models, correctly parameterised, can provide important information when estimating discrimination categories of needle damage.
A technique to estimate the pre-fire depth of burial of Grevillea seeds by using seedlings after fire
Authors: Auld Tony D. , Denham Andrew J.
Published: August 2005

In a glasshouse experiment, we used the shrub Grevillea speciosa to examine the reliability of estimating the depth of seed burial based on the distance from the soil surface to the junction of the swollen hypocotyl with the radicle. We then examined the applicability of the technique in the field by using post-fire seedling emergence. We found that the mean length of the swollen hypocotyl in seedlings was a good predictor of the depth of seed burial (R2 = 0.97). Most variation occurred for seeds buried near the surface at 2-cm depth, where the swollen hypocotyl overestimated the depth of seed burial by about 1 cm. There was a decline in the ability of seeds to successfully emerge from soil depths below 2 cm, with seedlings of G. speciosa able to emerge from soil depths up to 8 cm in the glasshouse. This corresponds with the estimated maximum emergence depth based on seed mass. In the field, seedlings were estimated to have emerged from depths of 1–7 cm after an intense wildfire. There was an approximately normal distribution of seedling emergence depths; however, the mode of this distribution varied among locations. The technique gave comparable results to a similar technique developed for Acacia spp., allowing consideration of a greater range of species and post-fire locations. Use of the technique has the potential to provide insights into the impacts of fires below ground, including the nature of post-fire germination, residual soil seed banks, the depth-related action of fire-induced germination cues and small-scale spatial variation.
Genetic diversity and regional identity in the Australian remnant Nothofagus moorei
Authors: Taylor K. J. , Lowe A. J. , Hunter R. J. , Ridgway T. , Gresshoff P. M. , Rossetto M.
Published: August 2005

Nothofagus moorei (F.Muell.) Krasser has a disjunct and narrow distribution in south-eastern Australian cool temperate rainforest. To assess the conservation-genetic priorities for this species, the genetic diversity of 20 populations sampled from the largest remnant patches at northern and southern distributional extremes, the McPherson and Barrington ranges (a total of 146 individuals), was investigated by using inter simple sequence repeats (ISSR). Regeneration in northern regions of N. moorei has been documented to be predominantly by vegetative means, but our results indicate little evidence of clonality outside the multi-stemmed rings of trees. In addition, genetic diversity was considerably higher in the northern (McPherson, h = 0.1613) than in the southern range (Barrington, h = 0.1159), and genetic differentiation was significantly positively correlated with geographic distance in the former region, but not the latter. Total intraspecific variation was moderate, as measured by Shannon’s diversity index, I = 0.2719, and Nei’s gene diversity, h = 0.1672, and is considered at the high end of spectrum for estimates of narrow endemic species. An analysis of molecular variation indicated that the majority of genetic variation is partitioned among individuals within population (60%; P < 0.001), rather than among populations within regions (10%; P < 0.001). However, a large and significant component of the measured diversity was partitioned between northern and southern regions (29%; P < 0.001). Several hypotheses are outlined to explain these differences and management implications are discussed. However, given the narrow range, poor dispersal mechanism and restriction to cool temperate rainforest, the continued existence of N. moorei is most threatened by environmental instability and habitat loss resulting from global climate change. In this context the northern regions of the species are most at risk and extinction of such populations would lead to a significant loss of genetic variation for the species as a whole.
Arrestin-related proteins mediate pH signaling in fungi
Authors: Herranz Silvia , Rodríguez José M. , Bussink Henk-Jan , Sánchez-Ferrero Juan C. , Arst Herbert N. , Peñalva Miguel A. , Vincent Olivier
Published: August 2005

Metazoan arrestins bind to seven-transmembrane (7TM) receptors to regulate function.
Aspergillus nidulans
PalF, a protein involved in the fungal ambient pH signaling pathway, contains arrestin N-terminal and C-terminal domains and binds strongly to two different regions within the C-terminal cytoplasmic tail of the 7TM, putative pH sensor PalH. Upon exposure to alkaline ambient pH, PalF is phosphorylated and, like mammalian β-arrestins, ubiquitinated in a signal-dependent and 7TM protein-dependent manner. Substitution in PalF of a highly conserved arrestin N-terminal domain Ser residue prevents PalF-PalH interaction and pH signaling
in vivo
. Thus, PalF is the first experimentally documented fungal arrestin-related protein, dispelling the notion that arrestins are restricted to animal proteomes. Epistasis analyses demonstrate that PalF posttranslational modification is partially dependent on the 4TM protein PalI but independent of the remaining pH signal transduction pathway proteins PalA, PalB, and PalC, yielding experimental evidence bearing on the order of participation of the six components of the pH signal transduction pathway. Our data strongly implicate PalH as an ambient pH sensor, possibly with the cooperation of PalI.
Duality of Hardy and BMO spaces associated with operators with heat kernel bounds
Authors: Duong Xuan , Yan Lixin
Published: August 2005

Let

L
L

be the infinitesimal generator of an analytic semigroup on

L
2

(

R

n

)

L^2({\mathbb R}^n)

with suitable upper bounds on its heat kernels. Auscher, Duong, and McIntosh defined a Hardy space

H
L
1

H_L^1

by means of an area integral function associated with the operator

L
L

. By using a variant of the maximal function associated with the semigroup

{

e

−
t
L

}

t
≥
0

\{e^{-tL}\}_{t\geq 0}

, a space

BMO

L

\textrm {BMO}_L

of functions of BMO type was defined by Duong and Yan and it generalizes the classical BMO space. In this paper, we show that if

L
L

has a bounded holomorphic functional calculus on

L
2

(

R

n

)

L^2({\mathbb R}^n)

, then the dual space of

H
L
1

H_L^1

is

BMO

L

∗

\textrm {BMO}_{L^{\ast }}

where

L

∗

L^{\ast }

is the adjoint operator of

L
L

. We then obtain a characterization of the space

BMO

L

\textrm {BMO}_L

in terms of the Carleson measure. We also discuss the dimensions of the kernel spaces

K

L

{\mathcal K}_L

of BMO

L

_{ L}

when

L
L

is a second-order elliptic operator of divergence form and when

L
L

is a Schrödinger operator, and study the inclusion between the classical BMO space and

BMO

L

\textrm {BMO}_L

spaces associated with operators.
Applying a Two-Step Strategy to the Analysis of Cross-National Public Opinion Data
Authors: Jusko Karen Long , Shively W. Phillips
Published: August 2005

In recent years, large sets of national surveys with shared content have increasingly been used for cross-national opinion research. But scholars have not yet settled on the most flexible and efficient models for utilizing such data. We present a two-step strategy for such analysis that takes advantage of the fact that in such datasets each “cluster” (i.e., country sample) is large enough to sustain separate analysis of its internal variances and covariances. We illustrate the method by examining a puzzle of comparative electoral behavior—why does turnout decline rather than increase with the number of parties competing in an election (Blais and Dobryzynska 1998, for example)? This discussion demonstrates the ease with which a two-step strategy incorporates confounding variables operating at different levels of analysis. Technical appendices demonstrate that the two-step strategy does not lose efficiency of estimation as compared with a pooling strategy.
Extensive editing of a small fraction of human T-cell leukemia virus type 1 genomes by four APOBEC3 cytidine deaminases
Authors: Mahieux Renaud , Suspène Rodolphe , Delebecque Frédéric , Henry Michel , Schwartz Olivier , Wain-Hobson Simon , Vartanian Jean-Pierre
Published: August 2005

In the absence of the human immunodeficiency virus type 1 (HIV-1) Vif protein, the host-cell cytidine deaminases APOBEC3F and -3G are co-packaged along with virion RNA. Upon infection of target cells, nascent single-stranded DNA can be edited extensively, invariably giving rise to defective genomes called G→A hypermutants. Although human T-cell leukemia virus type 1 (HTLV-1) replicates in the same cell type as HIV-1, it was shown here that HTLV-1 is relatively resistant to the antiviral effects mediated by human APOBEC3B, -3C, -3F and -3G. Nonetheless, a small percentage of genomes (0·1<f<5 %) were edited extensively: up to 97 % of cytidine targets were deaminated. In contrast, hypermutated HTLV-1 genomes were not identified in peripheral blood mononuclear cell DNA from ten patients with non-malignant HTLV-1 infection. Thus, although HTLV-1 DNA can indeed be edited by at least four APOBEC3 cytidine deaminases in vitro, they are conspicuously absent in vivo.
Beta interferon and gamma interferon synergize to block viral DNA and virion synthesis in herpes simplex virus-infected cells
Authors: Pierce Amy T. , DeSalvo Joanna , Foster Timothy P. , Kosinski Athena , Weller Sandra K. , Halford William P.
Published: August 2005

The capacity of herpes simplex virus type 1 (HSV-1) to replicate in vitro decreases tremendously when animal cell cultures are exposed to ligands of both the alpha/beta interferon (IFN-α/β) receptor and IFN-γ receptor prior to inoculation with low m.o.i.s of HSV-1. However, the available evidence provides no insight into the possible mechanisms by which co-activation of the IFN-α/β- and IFN-γ-signalling pathways produces this effect. Therefore, it has not been possible to differentiate between whether these observations represent an important in vitro model of host immunological suppression of HSV-1 infection or an irrelevant laboratory phenomenon. Therefore, the current study was initiated to determine whether co-activation of the host cell's IFN-α/β and IFN-γ pathways either (i) induced death of HSV-1-infected cells such that virus replication was unable to occur; or (ii) disrupted one or more steps in the process of HSV-1 replication. To this end, multiple steps in HSV-1 infection were compared in populations of Vero cells infected with HSV-1 strain KOS (m.o.i. of 2·5) and exposed to ligands of the IFN-α/β receptor, the IFN-γ receptor or both. The results demonstrated that IFN-β and IFN-γ interact in a synergistic manner to block the efficient synthesis of viral DNA and nucleocapsid formation in HSV-1-infected cells and do so without compromising host-cell viability. It was inferred that IFN-mediated suppression of HSV-1 replication may be a central mechanism by which the host immune system limits the spread of HSV-1 infection in vivo.
T1764G1766 core promoter double mutants are restricted to Hepatitis B virus strains with an A1757 and are common in genotype D
Authors: Sendi Hossein , Mehrab-Mohseni Marjan , Zali Mohammad R. , Norder Helene , Magnius Lars O.
Published: August 2005

To investigate the role of pre-core and basal core promoter (BCP) mutants in hepatitis B e antigen (HBeAg)-negative chronic hepatitis B (e-CHB) in Iran, Hepatitis B virus strains from 30 patients and 42 anti-HBe-positive asymptomatic carriers (ASCs) were characterized. G1896A pre-core stop mutants, detected in 77 % of e-CHB patients and 85 % of ASCs, showed no association with virus load or aminotransferase levels. Twenty per cent of e-CHB patients and 31 % of ASCs harboured T1762A1764 mutants. When this double mutation was associated with G1757, it was linked to a higher virus load in patients than when it was associated with A1757 (105·2±1·8 vs 103·2±0·8 copies ml−1; P=0·004). Interestingly, the most common BCP mutations were T1764 and G1766, which were present in 33 % of e-CHB patients and 29 % of ASCs. These were associated with higher virus load and aminotransferase levels compared with patients lacking core promoter mutations, although this was not significant. The T1764G1766 double mutation was only present in strains with A1757 (P<0·001), which is more frequent in strains of genotype D than in those belonging to other genotypes. On the other hand, the T1762A1764 double mutation was found more frequently in association with G1757 than with A1757. The T1762A1764 double mutation forms a binding site for hepatocyte nuclear factor 1 (HNF1), which is constrained by A1757. However, the T1764G1766 double mutant may form a binding site for HNF3. Thus, position 1757 affects the emergence of promoter double mutants and would predict a relative genotypic restriction of both the T1762A1764 and the T1764G1766 double mutants.
In vivo depletion of CD8+ T lymphocytes abrogates protective immunity to African swine fever virus
Authors: Oura C. A. L. , Denyer M. S. , Takamatsu H. , Parkhouse R. M. E.
Published: August 2005

To understand the mechanisms involved in protective immunity to African swine fever virus (ASFV) infection, the observation that infection with the avirulent Portuguese ASFV isolate OUR/T88/3 protects outbred pigs from challenge with the virulent Portuguese ASFV isolate OUR/T88/1 was exploited. It was demonstrated that pigs exposed to OUR/T88/3 and then depleted of CD8+lymphocytes were no longer fully protected from OUR/T88/1 challenge. This indicated that CD8+lymphocytes play an important role in the protective immune response to ASFV infection and that anti-ASFV antibody alone, from OUR/T88/3 infection, was not sufficient to protect pigs from OUR/T88/1 challenge. Inbred pigs of the cc haplotype infected with OUR/T88/3 were not always protected from OUR/T88/1 challenge and developed both viraemia and fever. Such viraemia was always correlated with increased numbers of circulating CD8β+lymphocytes, indicating a specific role for CD8β+lymphocytes in combating viraemia. These experiments indicate an important role for CD8+lymphocytes, particularly CD8β+lymphocytes, in ASF protective immunity.
Construction and characterization of infectious cDNA clones of a chicken strain of hepatitis E virus (HEV), avian HEV
Authors: Huang F. F. , Pierson F. W. , Toth T. E. , Meng X. J.
Published: August 2005

Hepatitis E virus (HEV), the causative agent of hepatitis E, is an important human pathogen. Increasing evidence indicates that hepatitis E is a zoonosis. Avian HEV was recently discovered in chickens with hepatitis–splenomegaly syndrome in the USA. Like swine HEV from pigs, avian HEV is also genetically and antigenically related to human HEV. The objective of this study was to construct and characterize an infectious cDNA clone of avian HEV for future studies of HEV replication and pathogenesis. Three full-length cDNA clones of avian HEV, pT7-aHEV-5, pT7G-aHEV-10 and pT7G-aHEV-6, were constructed and their infectivity was tested by in vitro transfection of leghorn male hepatoma (LMH) chicken liver cells and by direct intrahepatic inoculation of specific-pathogen-free (SPF) chickens with capped RNA transcripts from the three clones. The results showed that the capped RNA transcripts from each of the three clones were replication competent when transfected into LMH cells as demonstrated by detection of viral antigens with avian HEV-specific antibodies. SPF chickens intrahepatically inoculated with the capped RNA transcripts from each of the three clones developed active avian HEV infections as evidenced by seroconversion to avian HEV antibodies, viraemia and faecal virus shedding. The infectivity was further confirmed by successful infection of naïve chickens with the viruses recovered from chickens inoculated with the RNA transcripts. The results indicated that all three cDNA clones of avian HEV are infectious both in vitro and in vivo. The availability of these infectious clones for a chicken strain of HEV now affords an opportunity to study the mechanisms of HEV cross-species infection and tissue tropism by constructing chimeric viruses among human, swine and avian HEVs.
An internal RNA element in the P3 cistron of Wheat streak mosaic virus revealed by synonymous mutations that affect both movement and replication
Authors: Choi Il-Ryong , Horken Kempton M. , Stenger Drake C. , French Roy
Published: August 2005

Multiple synonymous substitution mutations in the Wheat streak mosaic virus P3 cistron did not affect translation in vitro but rendered the virus incapable of systemic infection. Multiple synonymous substitutions in the cylindrical inclusion cistron did not alter infectivity or in vitro translation. To assess replication and movement phenotypes, P3 mutations were placed in context with a GUS reporter gene. GUS activity measured in barley protoplasts 36 h post-transfection indicated that mutants with synonymous substitutions in P3 retained the ability to replicate at 22–80 % of wild-type levels. Almost no GUS activity was detected in protoplasts transfected with a P3 frame-shift mutant. Histochemical GUS assays conducted 3 days post-inoculation (p.i.) revealed genomes with multiple synonymous substitutions in P3, which were able to establish infection foci limited to small clusters of cells that increased in size only slightly by 5 days p.i. Infection foci produced by wild-type Wheat streak mosaic virus-expressing GUS were much larger at 3 days p.i. and had coalesced by 5 days p.i. No GUS activity was detected in plants inoculated with the frame-shift mutant bearing GUS. Three of four mutants, each with a single synonymous substitution in the 3′-proximal half of the P3 cistron, were wild-type with respect to systemic infectivity. A model RNA secondary structure obtained for the region was disrupted by the debilitating single mutation but not by the other three single mutations. Collectively, these results identify an internal RNA sequence element in the P3 cistron that affects both replication and movement of the viral genome.
HcPro, a multifunctional protein encoded by a plant RNA virus, targets the 20S proteasome and affects its enzymic activities
Authors: Ballut Lionel , Drucker Martin , Pugnière Martine , Cambon Florence , Blanc Stéphane , Roquet Françoise , Candresse Thierry , Schmid Hans-Peter , Nicolas Paul , Gall Olivier Le , Badaoui Saloua
Published: August 2005

The proteasome is a multicatalytic complex involved in many cellular processes in eukaryotes, such as protein and RNA turnover, cell division, signal transduction, transcription and translation. Intracellular pathogens are targets of its enzymic activities, and a number of animal viruses are known to interfere with these activities. The first evidence that a plant virus protein, the helper component-proteinase (HcPro) ofLettuce mosaic virus(LMV; genusPotyvirus), interferes with the 20S proteasome ribonuclease is reported here. LMV infection caused an aggregation of the 20S proteasome to high-molecular mass structuresin vivo, and specific binding of HcPro to the proteasome was confirmedin vitrousing two different approaches. HcPro inhibited the 20S endonuclease activityin vitro, while its proteolytic activities were unchanged or slightly stimulated. This ability of HcPro, a pathogenicity regulator of potyviruses, to interfere with some of the catalytic functions of the 20S proteasome suggests the existence of a novel type of defence and counter-defence interplay in the course of interaction between potyviruses and their hosts.
Antiviral effect of dehydroepiandrosterone on Japanese encephalitis virus infection
Authors: Chang Chia-Che , Ou Yen-Chuan , Raung Shue-Ling , Chen Chun-Jung
Published: August 2005

Japanese encephalitis virus(JEV), which causes neurological disorders, completes its life cycle and triggers apoptotic cell death in infected cells. Dehydroepiandrosterone (DHEA), an adrenal-derived steroid, has been implicated in protection against neurotoxicity and protection of animals from viral-induced encephalitis, resulting in an increased survival rate of the animals. Currently, the mechanisms underlying the beneficial effects of DHEA against the virus are largely unknown. In this study, DHEA suppression of JEV replication and virus-induced apoptosis in murine neuroblastoma (N18) cells was investigated. It was found that DHEA suppressed JEV-induced cytopathic effects, JEV-induced apoptotic cell death and JEV propagation in a concentration-dependent manner. Antiviral activity was more efficient in cultures treated with DHEA immediately after viral adsorption compared with that in cultures receiving delayed administration after adsorption or transient exposure before adsorption. JEV-induced cytotoxicity was accompanied by the inactivation of extracellular signal-regulated protein kinase (ERK). Inactivation of ERK by JEV infection was reversed by DHEA. When cells were treated with the ERK inhibitor U0126, DHEA lost its antiviral effect. Activation of ERK by anisomycin mimicked the action of DHEA in suppressing JEV-induced cytotoxicity. DHEA-related compounds, such as its sulfate ester (DHEAS) and pregnenolone, were unable to suppress JEV-induced cytotoxicity and ERK inactivation. The hormone-receptor antagonists ICI 182780 and flutamide failed to abrogate the antiviral effect of DHEA. These findings suggest that the antiviral effect of DHEA is not linked directly to the genomic steroid-receptor pathways and suggest that the signalling pathways of ERK play a role in the antiviral action of DHEA.
Mannose-binding lectin binds to Ebola and Marburg envelope glycoproteins, resulting in blocking of virus interaction with DC-SIGN and complement-mediated virus neutralization
Authors: Ji Xin , Olinger Gene G. , Aris Sheena , Chen Ying , Gewurz Henry , Spear Gregory T.
Published: August 2005

Mannose-binding lectin (MBL), a serum lectin that mediates innate immune functions including activation of the lectin complement pathway, binds to carbohydrates expressed on some viral glycoproteins. In this study, the ability of MBL to bind to virus particles pseudotyped with Ebola and Marburg envelope glycoproteins was evaluated. Virus particles bearing either Ebola (Zaire strain) or Marburg (Musoke strain) envelope glycoproteins bound at significantly higher levels to immobilized MBL compared with virus particles pseudotyped with vesicular stomatitis virus glycoprotein or with no virus glycoprotein. As observed in previous studies, Ebola-pseudotyped virus bound to cells expressing the lectin DC-SIGN (dendritic cell-specific intercellular adhesion molecule 3-grabbing non-integrin). However, pre-incubation of virus with MBL blocked DC-SIGN-mediated binding to cells, suggesting that the two lectins bind at the same or overlapping sites on the Ebola glycoprotein. Neutralization experiments showed that virus pseudotyped with Ebola or Marburg (Musoke) glycoprotein was neutralized by complement, while the Marburg (Ravn strain) glycoprotein-pseudotyped virus was less sensitive to neutralization. Neutralization was partially mediated through the lectin complement pathway, since a complement source deficient in MBL was significantly less effective at neutralizing viruses pseudotyped with filovirus glycoproteins and addition of purified MBL to the MBL-deficient complement increased neutralization. These experiments demonstrated that MBL binds to filovirus envelope glycoproteins resulting in important biological effects and suggest that MBL can interact with filoviruses during infection in humans.
Identification of immunoglobulin superfamily 11 (IGSF11) as a novel target for cancer immunotherapy of gastrointestinal and hepatocellular carcinomas
Authors: Watanabe Takeshi , Suda Takako , Tsunoda Takuya , Uchida Naotaka , Ura Katsuaki , Kato Tatsushi , Hasegawa Suguru , Satoh Seiji , Ohgi Shigetsugu , Tahara Hideaki , Furukawa Yoichi , Nakamura Yusuke
Published: August 2005

We previously performed gene expression profile analyses of 20 intestinal‐type gastric cancers, and identified a set of genes whose expression levels were elevated in cancer tissues compared to their corresponding non‐cancerous tissues. In the present study we focused on the immunoglobulin superfamily 11 gene (IGSF11). Its expression was also elevated in colorectal cancers and hepatocellular carcinomas as well as intestinal‐type gastric cancers. Northern blot analysis showed that it was expressed abundantly in testis and ovary. These data suggest that IGSF11 is a good candidate of cancer‐testis antigen. Furthermore, suppression of IGSF11 by siRNA retarded the growth of gastric cancer cells. To investigate the possibility of clinical application of peptide vaccine to IGSF11, we synthesized candidate epitope peptides for IGSF11 and tested whether the peptides elicit IGSF11‐specific CTL. As a result, we successfully established oligo‐clonal CTL by stimulation with IGSF11‐9‐207 (ALSSGLYQC). In addition, we also established additional CTL using IGSF11‐9V (ALSSGLYQV), anchor‐modified peptides of IGSF11‐9‐207. These peptides showed IGSF11‐specific cytotoxic activity in an HLA‐A*0201‐restricted fashion, suggesting that these peptides may be applicable for cancer immunotherapy. These findings have provided a novel insight into carcinogenesis of the stomach, colon and liver, and will be helpful for the development of novel therapeutic strategies to a wide range of human cancers. (Cancer Sci 2005; 96: 498 –506)
Loss of TSLC1 expression in lung adenocarcinoma: Relationships with histological subtypes, sex and prognostic significance
Authors: Goto Akiteru , Niki Toshiro , Chi‐pin Li , Matsubara Daisuke , Murakami Yoshinori , Funata Nobuaki , Fukayama Masashi
Published: August 2005

The TSLC1 (tumor suppressor in lung cancer 1) gene is a tumor suppressor recently identified through functional complementation in a lung adenocarcinoma cell line A549. In this study we immunohistochemically examined the loss of TSLC1 expression in 93 cases of surgically resected lung adenocarcinoma, and investigated its correlation with clinicopathological parameters, including histological subtypes of tumors. The prognostic significance of loss of TSLC1 expression was analyzed by univariate and multivariate analyses, in parallel with other prognostic markers such as p53, p27, and Ki‐67. In non‐cancerous lung tissue, TSLC1 was weakly positive in bronchial and bronchiolar epithelial cells, type II pneumocytes and bronchial glands. Overall, TSLC1 was negative in 60 of 93 lung adenocarcinomas. TSLC1 was mainly localized in the cytoplasm of the cells, but cell membrane staining was also observed, especially at sites of cell–cell adhesion. TSLC1‐negative tumors were more frequently observed in male cases (41/54 cases, 70.0%) than in female cases (19/39 cases, 48.7%) (P < 0.01). Notably, TSLC1 expression was preserved in a non‐invasive, bronchiolo‐alveolar histological pattern of tumor cells (P < 0.0001). Survival analyses showed that loss of TSLC1 expression was associated with lower patient survival in univariate and multivariate analyses (P < 0.05 and P = 0.059, respectively). Subset analyses further showed that the prognostic impact of loss of TSLC1 was significant for male patients (P = 0.0089), but not for female patients. We conclude that TSLC1 is expressed in a subset of lung adenocarcinomas, especially in those with bronchiolo‐alveolar spread pattern. Loss of TSLC1 is associated with lower patient survival, supporting its role as a tumor suppressor. (Cancer Sci 2005; 96: 480 –486)
Telomerase reverse transcriptase mRNA expression in peripheral lymphocytes of patients with chronic HBV and HCV infections
Authors: Satra M. , Dalekos G. N. , Kollia P. , Vamvakopoulos N. , Tsezou A.
Published: August 2005

Summary.  Telomerase activity is present at low levels in peripheral lymphocytes (PL) and is upregulated upon activation, possibly protecting PL from telomere shortening. As decreased telomere length is considered a sign of cellular senescence, telomerase may, therefore, play an important role on immune function, organ regeneration and carcinogenesis. So far, quantification of human telomerase reverse transcriptase levels (hTERT) in PL, has not been reported. We determined hTERT mRNA levels in PL of hepatitis B virus (HBV) and hepatitis C virus (HCV) patients, in an attempt to address whether hTERT transcripts in PL are altered in these viral diseases, which are characterized by immune dysfunction and increased incidence of hepatocarcinogenesis. hTERT mRNA levels in PL of HBV (n = 17), HCV (n = 24) patients and healthy controls (n = 22) were quantified by real‐time polymerase chain reaction. We observed significantly lower hTERT mRNA levels in HBV and HCV patients compared with healthy individuals (P < 0.05). hTERT mRNA levels were not associated with the patients’ clinical status (inactive, hepatitis and cirrhosis). Also no correlation was observed between hTERT mRNA expression, and HBV and HCV replicative activity. In the inactive group (n = 18) we observed a negative correlation between hTERT mRNA expression and disease duration (rs = −0.52, P < 0.03). We performed for the first time an accurate quantification of hTERT mRNA expression in PL of HBV and HCV patients. The observed low levels of hTERT mRNA expression in the above patients may suggest its involvement in the immunopathogenesis of chronic viral hepatitis.