bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Tip Clearance on the Thermal and Hydrodynamic Performance
of a Shrouded Pin Fin Array
Authors: Moores Kevin A. , Joshi Yogendra K.
Published: November 2003

The effect of introducing tip clearance to a liquid cooled array of shrouded pins fins is examined. Three arrays of height to diameter ratio ranging from 0.5 to 1.1 were evaluated experimentally. The arrays were exposed to a uniform heat flux of 0.02 to 0.26 W/mm2 and cooled with water through a nominal Reynolds number range of 200 to 10,000. Tip clearance of 0 to 25% of pin height was assessed. Mean heat transfer rates and adiabatic pressure drop across the array were determined and empirical correlations are proposed. The introduction of clearance was seen to increase overall heat transfer in some cases.
Nanoparticles Formed in Picosecond Laser Argon Crystal Interaction
Authors: Wang Xinwei , Xu Xianfan
Published: November 2003

In this work, Molecular Dynamics simulations are conducted to attain thermal and mechanical characteristics of nanoparticles formed in laser materials interaction. It reveals that nanoparticles originate from intense vapor phase explosion. A gas-like structure is observed in nanoparticles in the initial stage of formation. After a short time of evolution, a typical liquid structure is revealed in particles. As a direct consequence of atoms escaping from the particle surface, the temperature of nanoparticles reduces to an under-cooling point from the initial super-heating state. Furthermore, it indicates that movements of nanoparticles are dominated by those normal to the target surface.
Ultra High Critical Heat Flux During Forced Flow Boiling Heat
Transfer With an Impinging Jet
Authors: Mitsutake Yuichi , Monde Masanori
Published: November 2003

An ultra high critical heat flux (CHF) was attempted using a highly subcooled liquid jet impinging on a small rectangular heated surface of length 5∼10mm and width 4 mm. Experiments were carried out at jet velocities of 5∼60m/s, a jet temperature of 20°C and system pressures of 0.1∼1.3MPa. The degree of subcooling was varied from 80 to 170 K with increasing system pressure. The general correlation for CHF is shown to be applicable for such a small heated surface under a certain range of conditions. The maximum CHF achieved in these experiments was 211.9 MW/m2, recorded at system pressure of 0.7 MPa, jet velocity of 35 m/s and jet subcooling of 151 K, and corresponds to 48% of the theoretical maximum heat flux proposed by Gambill and Lienhard.
The Optimum Height of Winglet Vortex Generators Mounted on Three-Row
Flat Tube Bank Fin
Authors: Gao S. D. , Wang L. B. , Zhang Y. H. , Ke F.
Published: November 2003

Winglet vortex generators can be used to enhance the heat transfer performance of finned flat tube bank fin. The effects of the height of vortex generators (VG) on local heat transfer were studied using the naphthalene sublimation method and the optimum height of winglet VG are screened by using JF, a dimensionless factor of the larger the better characteristics. In order to get JF, the local heat transfer coefficient obtained in experiments and a numerical method were used to get the heat transferred from the fin. For the configurations studied in this paper: for local characteristic, as increasing height of VG, heat transfer is enhanced, but the mostly enhanced region moves away from the tube wall; with increasing height of VG to certain degree, the width of enhanced region does not increase significantly; the effects of VG’s height on span-average Nusselt number (Nu) are more mixed on fin surface mounted with VGs and its back surface, with increasing height of VG, in some region heat transfer is worsened, and in other region heat transfer is enhanced; in real working condition, the heat transferred from fin surface mounted with VGs is larger than the heat transferred from the other surface of the fin; increasing the height of VG (H) increases average Nu and friction factor (f ), but with considering the fin efficiency, there is an optimum H to get best heat transfer performance; the optimum height of VG is dependent on the thickness of fin and its heat conductivity, for mostly used fin thickness and material, the optimum height of VG is 0.8 times of net fin spacing.
Investigation of Decisive Mixture Effects in Nucleate Boiling of
Binary Mixtures Using a Theoretical Model
Authors: Kern Jürgen , Stephan Peter
Published: November 2003

In the present paper an attempt is made to clarify the influence of mixture effects upon heat transfer in nucleate boiling of binary mixtures. The studies are based on a theoretical model that is briefly summarized. Evaluating heat and mass transfer around a single vapor bubble emphasizes a strong influence of the so-called micro region where the liquid-vapor phase interface approaches the wall. Due to the preferential evaporation of one component of the mixture, strong concentration gradients occur in the micro region. These microscale composition effects cause diffusive mass transfer, Marangoni convection, and a variation of the liquid-vapor phase equilibrium as well as a variation of the thermophysical properties. From a macroscopic point of view the bubble site density and the departure diameter vary with the composition of the liquid. By means of parameter studies decisive mixture effects are identified and their relevance in the nucleate boiling process is stated. The heat transfer coefficient crucially depends on the bubble site density and departure diameter. For increasing bubble site density, the influence of microscopic concentration gradients increases. But only the variation of liquid-vapor phase equilibrium becomes important, while diffusive mass transfer and Marangoni convection can be neglected.
Theoretical Model for Nucleate Boiling Heat and Mass Transfer of
Binary Mixtures
Authors: Kern Jürgen , Stephan Peter
Published: November 2003

A model is presented to calculate nucleate boiling heat transfer coefficients of binary mixtures. The model includes the governing physical phenomena, such as the variation of the phase interface curvature, the adhesion pressure between wall and liquid, the interfacial thermal resistance as well as the local variation of composition and liquid-vapor equilibrium. Marangoni convection is considered, too. The theoretical background of these phenomena is described and their implementation is explained. The model is verified by comparing calculated heat transfer coefficients of hydrocarbon mixtures with experimental data. Computational and experimental data are in good agreement. In the examples a considerable amount of the total heat flow passes through a tiny thin film area, called micro region, where the liquid-vapor phase interface is attached to the wall. Very high spatial gradients of heat flux and mixture concentration occur interacting with overall heat transfer performance.
Phonon Transport in Anisotropic Scattering Particulate Media
Authors: Prasher Ravi
Published: November 2003

Equation of phonon radiative transport (EPRT) is rewritten to include anisotropic scattering by a particulate media by including an acoustic phase function and an inscattering term which makes EPRT exactly same as equation of radiative transport (ERT). This formulation of EPRT is called generalized EPRT (GEPRT). It is shown that GEPRT reduces to EPRT for isotropic scattering and is totally consistent with phonon transport theory, showing that transport cross section is different from the scattering cross section. GEPRT leads to same formulation for transport cross section as given by phonon transport theory. However GEPRT shows that transport cross section formulations as described by phonon transport theory are only valid for acoustically thick medium. Transport cross section is different for the acoustically thin medium leading to the conclusion that mean free path (m.f.p) is size dependant. Finally calculations are performed for two types of scatterers for acoustic waves without mode conversion: (1) acoustically hard Rayleigh sphere; and (2) large sphere in the geometrical scattering regime. Results show that the scattering from these particles is highly anisotropic. It is also shown that for geometrical scattering case isotropic scattering leads to the conclusion of total internal reflection at the particle/medium interface.
An Improved Quasi-Steady Analysis for Solving Freezing Problems in a Plate, a Cylinder and a Sphere
Authors: Lin Sui , Jiang Zheng
Published: November 2003

Freezing processes taking place in a plate, a cylinder and a sphere are investigated by using the improved quasi-steady analysis model developed in the present study. In the improved quasi-steady analysis, an additional term is added to the temperature profile to simulate the transient effect on the temperature distribution in the solid phase. This additional term is based on the ratio of the heat flux at the phase boundary to that at the cooling surface, and physically, presents the thermal capacity effect in the frozen region. The maximum relative error of the moving phase front location obtained from the improved quasi-steady analysis is about 3% in comparison with that obtained from the exact solution of the freezing process in a plate. Since there is no exact solution available for the freezing process taking place in a cylinder or a sphere, the results obtained from the improved quasi-steady analysis are compared with results from references. The maximum relative errors of the improved quasi-steady analysis for the cylindrical and spherical cases are less than 4% while the maximum relative errors of the quasi-steady approximation are higher than 42%. It is evident that the improved quasi-steady analysis developed in the present study maintains the simplicity of the quasi-steady approximation while greatly increasing its accuracy.
Minimum Fuel Consumption and CO Emission and Optimum Speed of the Motorcycle with a CVT
Authors: Huang Yuan Mao , Hu Bi Shyang
Published: November 2003

The simulated annealing algorithm with the Bessel method for curve fitting and the tensor product method for surface fitting is used to transform engine discrete experimental data into a form that enables these data to be incorporated in the optimization process. Optimum curves of the engine torque versus the engine rotational speed and the engine rotational speed versus the motorcycle speed for the fuel consumption and the carbon monoxide (CO) emission are obtained for a motorcycle with a continuously variable transmission (CVT). The engine rotational speed at which a motorcycle begins to move for the specific engine data is obtained. From design parameters, engine rotational speeds corresponding to the maximum and minimum CVT speed ratio change, the minimum fuel consumption and CO emission, and optimum design variables can be determined.
One-Way Control of
FWA
Imprinting in
Arabidopsis
Endosperm by DNA Methylation
Authors: Kinoshita Tetsu , Miura Asuka , Choi Yeonhee , Kinoshita Yuki , Cao Xiaofeng , Jacobsen Steven E. , Fischer Robert L. , Kakutani Tetsuji
Published: November 2003

The
Arabidopsis FWA
gene was initially identified from late-flowering epigenetic mutants that show ectopic
FWA
expression associated with heritable hypomethylation of repeats around transcription starting sites. Here, we show that wild-type
FWA
displays imprinted (maternal origin–specific) expression in endosperm. The
FWA
imprint depends on the maintenance DNA methyltransferase MET1, as is the case in mammals. Unlike mammals, however, the
FWA
imprint is not established by allele-specific de novo methylation. It is established by maternal gametophyte–specific gene activation, which depends on a DNA glycosylase gene,
DEMETER
. Because endosperm does not contribute to the next generation, the activated
FWA
gene need not be silenced again. Double fertilization enables plants to use such “one-way” control of imprinting and DNA methylation in endosperm.
Plasmodium falciparum
Is Able To InvadeErythrocytes through a Trypsin-Resistant Pathway Independent ofGlycophorinB
Authors: Gaur Deepak , Storry Jill R. , Reid Marion E. , Barnwell John W. , Miller Louis H.
Published: November 2003

Plasmodium
falciparum
invades erythrocytes through multiple ligand-receptor
interactions, with redundancies in each pathway. One such alternate
pathway is the trypsin-resistant pathway that enables
P.
falciparum
to invade trypsin-treated erythrocytes. Previous
studies have shown that this trypsin-resistant pathway is dependent on
glycophorin B, as
P. falciparum
strains invade
trypsin-digested glycophorin B-deficient erythrocytes at a highly
reduced efficiency. Furthermore, in a recent study, the
P.
falciparum
7G8 strain did not invade glycophorin B-deficient
erythrocytes, a finding that was not confirmed in the present study. To
analyze the degree of dependence on glycophorin B for invasion by
P. falciparum
through the trypsin-resistant pathway, we have
studied the invasion phenotypes of five parasite strains, 3D7, HB3,
Dd2, 7G8, and Indochina I, on trypsin-treated normal and glycophorin
B-deficient erythrocytes. Invasion was variably reduced in glycophorin
B-deficient erythrocytes. Four strains, 3D7, HB3, Dd2, and Indochina I,
invaded trypsin-treated erythrocytes, while invasion by the 7G8 strain
was reduced by 90%. Among the four strains, invasion by 3D7,
HB3, and Dd2 of trypsin-digested glycophorin B-deficient erythrocytes
was further reduced. However, Indochina I invaded trypsin-digested
glycophorin B-deficient erythrocytes at the same efficiency as its
invasion of trypsin-digested normal erythrocytes. This strongly
suggests that the Indochina I strain of
P. falciparum
is not
dependent on glycophorin B to invade through a trypsin-resistant
pathway as are the strains 3D7, HB3, and Dd2. Thus,
P.
falciparum
is able to invade erythrocytes through a glycophorin
B-independent, trypsin-resistant
pathway.
Listeria monocytogenesMutants That Fail To Compartmentalize Listerolysin O Activity Are Cytotoxic, Avirulent, and Unable To Evade Host Extracellular Defenses
Authors: Glomski Ian J. , Decatur Amy L. , Portnoy Daniel A.
Published: November 2003

Listeria monocytogenesis a facultative intracellular bacterial pathogen that escapes from a phagosome and grows in the host cell cytosol. Escape of the bacterium from the phagosome to the cytosol is mediated by the bacterial pore-forming protein listeriolysin O (LLO). LLO has multiple mechanisms that optimize activity in the phagosome and minimize activity in the host cytosol. Mutants that fail to compartmentalize LLO activity are cytotoxic and have reduced virulence. We sought to determine why cytotoxic bacteria have attenuated virulence in the mouse model of listeriosis. In this study, we constructed a series of strains with mutations in LLO and with various degrees of cytotoxicity. We found that the more cytotoxic the strain in cell culture, the less virulent it was in mice. Induction of neutropenia increased the relative virulence of the cytotoxic strains 100-fold in the spleen and 10-fold in the liver. The virulence defect was partially restored in neutropenic mice by adding gentamicin, an antibiotic that kills extracellular bacteria. Additionally,L. monocytogenesgrew more slowly in extracellular fluid (mouse serum) than within tissue culture cells. We concluded thatL. monocytogenescontrols the cytolytic activity of LLO to maintain its nutritionally rich intracellular niche and avoid extracellular defenses of the host.
Modulation of Polymorphonuclear Cell Interleukin-8 Secretion by Human Monoclonal Antibodies to Type 8 Pneumococcal Capsular Polysaccharide
Authors: Burns Tamika , Zhong Zhaojing , Steinitz Michael , Pirofski Liise-anne
Published: November 2003

Pneumococcal capsular polysaccharide (PS) vaccines induce type-specific immunoglobulin M (IgM), IgG, and IgA. Type-specific IgG to the PS is sufficient to confer protection against the homologous serotype of the pneumococcus, but the efficacies of type-specific IgM and IgA are less well understood. We examined the in vitro activities and efficacies in mice of two human monoclonal antibodies (MAbs) to type 8 PS, NAD (IgA) and D11 (IgM). MAb-mediated opsonophagocytic killing was evaluated after coculture of type 8 pneumococci with human polymorphonuclear cells (PMNs), type-specific or control MAbs, and human complement sources. The effects of the MAbs on PMN interleukin-8 (IL-8) and IL-6 secretion were determined in supernatants from cocultures containing pneumococci and PMNs by enzyme-linked immunosorbent assay. MAb efficacy was determined in an intratracheal model of type 8 infection in mice with classical complement pathway deficiency. Both MAbs were protective in 100% of infected mice. Neither MAb promoted a significant amount of killing of type 8 pneumococci compared to its isotype control MAb. Both type-specific MAbs mediated complement-dependent modulation of PMN IL-8 secretion, with increased secretion at effector/target (E:T) ratios of 500:1 and 50:1 and reduced secretion at 1:5. Trypan blue staining revealed that PMNs cocultured with D11 were less viable at an E:T ratio of 1:5 than PMNs cocultured with the control MAb. PMN IL-6 secretion was increased by both type-specific and control MAbs. These results suggest that certain type-specific IgM and IgAs might contribute to host defense by modulation of the inflammatory response to pneumococci.
Functional Analysis of the
Mycobacterium tuberculosis
MprAB Two-Component SignalTransductionSystem
Authors: Zahrt Thomas C. , Wozniak Christopher , Jones Denise , Trevett Andrea
Published: November 2003

The
mechanisms utilized by
Mycobacterium tuberculosis
to
establish, maintain, or reactivate from latent infection in the host
are largely unknown but likely include genes that mediate adaptation to
conditions encountered during persistence. Previously, a two-component
signal transduction system,
mprAB
, was found to be required in
M. tuberculosis
for establishment and maintenance of
persistent infection in a tissue- and stage-specific fashion. To begin
to characterize the role of this system in
M. tuberculosis
physiology and virulence, a functional analysis of the
mprA
and
mprB
gene products was initiated. Here, evidence is
presented demonstrating that sensor kinase MprB and response regulator
MprA function as an intact signal-transducing pair in vitro and in
vivo. Sensor kinase MprB can be autophosphorylated, can donate
phosphate to MprA, and can act as a phospho-MprA phosphatase in vitro.
Correspondingly, response regulator MprA can accept phosphate from MprB
or from small phosphodonors including acetyl phosphate. Mutagenesis of
residues His249 in MprB and Asp48 in MprA abolished the
ability of these proteins to be phosphorylated in vitro. Introduction
of these alleles into
Mycobacterium bovis
BCGattenuated virulence in macrophages in vivo. Together, these results
support a role for the
mprAB
two-component system in
M.
tuberculosis
physiology and pathogenesis. Characterization of
two-component signal transduction systems will enhance our
understanding of processes regulated by
M. tuberculosis
during
acute and/or persistent infection in the
host.
Disruptionof Cell Polarity by Enteropathogenic
Escherichia coli
EnablesBasolateral Membrane Proteins To Migrate Apically and ToPotentiate PhysiologicalConsequences
Authors: Muza-Moons Michelle M. , Koutsouris Athanasia , Hecht Gail
Published: November 2003

Enteropathogenic
Escherichia coli
(EPEC) disrupts the structure and barrier
function of host intestinal epithelial tight junctions (TJs). The
impact of EPEC on TJ “fence function,” i.e.,
maintenance of cell polarity, has not been investigated. In polarized
cells, proteins such as β
1
-integrin and
Na
+
/K
+
ATPase are restricted to
basolateral (BL) membranes. The outer membrane EPEC protein intimin
possesses binding sites for the EPEC translocated intimin receptor
(Tir) and β
1
-integrin. Restriction ofβ
1
-integrin to BL domains, however, precludes
opportunity for interaction. We hypothesize that EPEC perturbs TJ fence
function and frees BL proteins such as β
1
-integrin
to migrate to apical (AP) membranes of host cells, thus allowing
interactions with bacterial adhesins such as intimin. The aim of this
study was to determine whether EPEC alters the polar distribution of BL
proteins, in particular β
1
-integrin, and if such
redistribution contributes to pathogenesis. Human intestinal epithelial
T84 cells and EPEC strain E2348/69 were used. Selective biotinylation
of AP or BL membrane proteins and confocal microscopy showed the
presence of β
1
-integrin and
Na
+
/K
+
ATPase on the AP membrane
following infection. β
1
-Integrin antibody afforded
no protection against the initial EPEC-induced decrease in
transepithelial electrical resistance (TER) but halted the progressive
decrease at later time points. While the effects of EPEC on TJ barrier
and fence function were Tir dependent, disruption of cell polarity by
calcium chelation allowed a
tir
mutant to be nearly as
effective as wild-type EPEC. In contrast, deletion of
espD
,
which renders the type III secretory system ineffective, had no effect
on TER even after calcium chelation, suggesting that the putativeβ
1
-integrin-intimin interaction serves to
provide intimate contact, like that of Tir and intimin, making
translocation of effector molecules more efficient. We conclude that
the initial alterations of TJ barrier and fence function by EPEC are
Tir dependent but that later disruption of cell polarity and
accessibility of EPEC to BL membrane proteins, such asβ
1
-integrin, potentiates the physiological
perturbations.
TheSiderophore Receptor IroN of Extraintestinal Pathogenic
Escherichia coli
Is a Potential VaccineCandidate
Authors: Russo Thomas A. , McFadden Catherine D. , Carlino-MacDonald Ulrike B. , Beanan Janet M. , Olson Ruth , Wilding Gregory E.
Published: November 2003

It
would be medically and economically desirable to prevent the millions
of annual extraintestinal infections and the thousands of associated
deaths due to
Escherichia coli
. Outer membrane
proteins are potential vaccine candidates for the prevention of these
infections. This study tested the hypotheses that the siderophore
receptor IroN is antigenic and that an IroN-specific antibody response
confers protection in vivo. Subcutaneous immunization with denatured
IroN resulted in a significant IroN immunoglobulin G (IgG)-specific
response in serum (
P
< 0.0001) but not a systemic or
mucosal IroN-specific IgA response. In a mouse model of ascending
urinary tract infection, subcutaneous immunization with denatured IroN
conferred significant protection against renal (
P
=
0.0135 and 0.0095 in two independent experiments), but not bladder,
infection. These data, together with the previously demonstrated role
of IroN in virulence, its expression in human biologic fluids, and its
prevalence among extraintestinal pathogenic
E. coli
strains, support further studies on the role of IroN as a vaccine
candidate.
Deletionof
Mycobacterium tuberculosis
Sigma Factor E Results inDelayed Time to Death with Bacterial Persistence in the Lungsof Aerosol-InfectedMice
Authors: Ando Masaru , Yoshimatsu Tetsuyuki , Ko Chiew , Converse Paul J. , Bishai William R.
Published: November 2003

The
stress-induced extracytoplasmic sigma factor E (SigE) of
Mycobacterium tuberculosis
shows increased expression after
heat shock, sodium dodecyl sulfate treatment, and oxidative stress, as
well as after phagocytosis in macrophages. We report that deletion of
sigE
results in delayed lethality in mice without a
significant reduction of bacterial numbers in
lungs.
Functional BvgAS Virulence Control System in
Bordetella bronchiseptica
Is Necessary for Induction of Ca
2+
Transients in Ciliated Tracheal Epithelial Cells
Authors: Groathouse Nathan A. , Heinzen Robert A. , Boitano Scott
Published: November 2003

To study initial
Bordetella bronchiseptica
-tracheal epithelial cell interactions, we coincubated
B. bronchiseptica
with rabbit tracheal explant cultures and assayed bacterial adherence and host cell Ca
2+
signaling. Wild-type
B. bronchiseptica
(RB50) preferentially adhered to cilia and induced ciliated host cell Ca
2+
transients within 2 min of coincubation, whereas coincubation with an avirulent strain (RB57) resulted in limited binding and Ca
2+
signaling. The described cell system allows for assessment of initial
B. bronchiseptica
-host cell interactions that can contribute to pathogenicity or to host cell defense.
Further Evidence that Papillomavirus Capsids Exist inTwo DistinctConformations
Authors: Selinka Hans-Christoph , Giroglou Tzenan , Nowak Thorsten , Christensen Neil D. , Sapp Martin
Published: November 2003

Cell
surface heparan sulfate proteoglycans (HSPGs) serve as primary
attachment receptors for human papillomaviruses (HPVs). To demonstrate
that a biologically functional HPV-receptor interaction is restricted
to a specific subset of HSPGs, we first explored the role of HSPG
glucosaminoglycan side chain modifications. We demonstrate that HSPG O
sulfation is essential for HPV binding and infection, whereas
de-N-sulfated heparin interfered with VLP binding but not with HPV
pseudoinfection. This points to differences in VLP-HSPG and
pseudovirion-HSPG interactions. Interestingly, internalization kinetics
of VLPs and pseudovirions, as measured by fluorescence-activated cell
sorting analysis, also differ significantly with approximate half times
of 3.5 and 7.5 h, respectively. These data suggest that
differences in HSPG binding significantly influence postbinding events.
We also present evidence that pseudovirions undergo a conformational
change after cell attachment. A monoclonal antibody (H33.J3), which
displays negligible effectiveness in preattachment neutralization
assays, efficiently neutralizes cell-bound virions. However, no
difference in H33.J3 binding to pseudovirions and VLPs was observed in
enzyme-linked immunosorbent assay and virus capture assays. In contrast
to antibody H33.B6, which displays equal efficiencies in pre- and
postattachment neutralization assays, H33.J3 does not block VLP binding
to heparin, demonstrating that it interferes with steps subsequent to
virus binding. Our data strongly suggest that H33.J3 recognizes a
conformation-dependent epitope in capsid protein L1, which undergoes a
structural change after cell
attachment.
Changes in Small Intestinal Homeostasis, Morphology,and Gene Expression during Rotavirus Infection of InfantMice
Authors: Boshuizen Jos A. , Reimerink Johan H. J. , Korteland-van Male Anita M. , van Ham Vanessa J. J. , Koopmans Marion P. G. , Büller Hans A. , Dekker Jan , Einerhand Alexandra W. C.
Published: November 2003

Rotavirus is the most important cause of infantile gastroenteritis. Since in vivo mucosal responses to a rotavirus infection thus far have not been extensively studied, we related viral replication in the murine small intestine to alterations in mucosal structure, epithelial cell homeostasis, cellular kinetics, and differentiation. Seven-day-old suckling BALB/c mice were inoculated with 2 × 104focus-forming units of murine rotavirus and were compared to mock-infected controls. Diarrheal illness and viral shedding were recorded, and small intestinal tissue was evaluated for rotavirus (NSP4 and structural proteins)- and enterocyte-specific (lactase, SGLT1, and L-FABP) mRNA and protein expression. Morphology, apoptosis, proliferation, and migration were evaluated (immuno)histochemically. Diarrhea was observed from days 1 to 5 postinfection, and viral shedding was observed from days 1 to 10. Two peaks of rotavirus replication were observed at 1 and 4 days postinfection. Histological changes were characterized by the accumulation of vacuolated enterocytes. Strikingly, the number of vacuolated cells exceeded the number of cells in which viral replication was detectable. Apoptosis and proliferation were increased from days 1 to 7, resulting in villous atrophy. Epithelial cell turnover was significantly higher (<4 days) than that observed in controls (7 days). Since epithelial renewal occurred within 4 days, the second peak of viral replication was most likely caused by infection of newly synthesized cells. Expression of enterocyte-specific genes was downregulated in infected cells at mRNA and protein levels starting as early as 6 h after infection. In conclusion, we show for the first time that rotavirus infection induces apoptosis in vivo, an increase in epithelial cell turnover, and a shutoff of gene expression in enterocytes showing viral replication. The shutoff of enterocyte-specific gene expression, together with the loss of mature enterocytes through apoptosis and the replacement of these cells by less differentiated dividing cells, likely leads to a defective absorptive function of the intestinal epithelium, which contributes to rotavirus pathogenesis.
TheCentral Region of Human T-Cell Leukemia Virus Type 1 TaxProtein Contains Distinct Domains Involved inSubunitDimerization
Authors: Basbous Jihane , Bazarbachi Ali , Granier Claude , Devaux Christian , Mesnard Jean-Michel
Published: November 2003

The
Tax protein of human T-cell leukemia virus type 1 (HTLV-1) can form
homodimers. Tax dimerization contributes to optimal Tax activity
involved in transactivation of the HTLV-1 promoter. The mechanisms used
to form specific Tax dimers are poorly understood because the domains
that mediate such interactions have not been clearly characterized.
Here we have used different approaches (the two-hybrid assay in yeast,
the glutathione
S
-transferase pull-down assay, and the Spot
method) to study Tax-Tax interactions. Our results indicate that the
integrity of the sequence of Tax, except for the last 16 amino acids
(residues 338 to 353), is critical, suggesting that Tax dimerization is
dictated more by secondary structure than by primary structure. We
were, however, able to delimit a central region involved in Tax
self-association that encompasses the residues 127 to 228. This region
can be divided into three subdomains of dimerization: DD1 (residues 127
to 146), DD2 (residues 181 to 194), and DD3 (residues 213 to 228).
Moreover, the Tax mutants M22 (T130A and L131S) and M29 (K189A and
R190S), with amino acid substitutions located in DD1 and DD2,
respectively, were found to be impaired in Tax
self-association.
Comparison of the Structures of Three Circoviruses:
Chicken Anemia Virus
,
Porcine
Circovirus Type 2
, and
Beak
and Feather Disease
Virus
Authors: Crowther R. A. , Berriman J. A. , Curran W. L. , Allan G. M. , Todd D.
Published: November 2003

Circoviruses
are small, nonenveloped icosahedral animal viruses characterized by
circular single-stranded DNA genomes. Their genomes are the smallest
possessed by animal viruses. Infections with circoviruses, which can
lead to economically important diseases, frequently result in
virus-induced damage to lymphoid tissue and immunosuppression. Within
the family
Circoviridae
, different genera are distinguished by
differences in genomic organization. Thus,
Chicken
anemia virus
is in the genus
Gyrovirus
,
while porcine circoviruses and
Beak and
feather disease virus
belong to the genus
Circovirus
. Little is known about the structures of
circoviruses. Accordingly, we investigated the structures of these
three viruses with a view to determining whether they are related.
Three-dimensional maps computed from electron micrographs showed that
all three viruses have a T=1 organization with capsids formed
from 60 subunits. Porcine circovirus type 2 and beak and feather
disease virus show similar capsid structures with flat pentameric
morphological units, whereas chicken anemia virus has stikingly
different protruding pentagonal trumpet-shaped units. It thus appears
that the structures of viruses in the same genus are related but that
those of viruses in different genera are
unrelated.
Infection and Injury of Neurons by West NileEncephalitisVirus
Authors: Shrestha Bimmi , Gottlieb David , Diamond Michael S.
Published: November 2003

West Nile virus (WNV) infects neurons and leads to encephalitis, paralysis, and death in humans, animals, and birds. We investigated the mechanism by which neuronal injury occurs after WNV infection. Neurons in the anterior horn of the spinal cords of paralyzed mice exhibited a high degree of WNV infection, leukocyte infiltration, and degeneration. Because it was difficult to distinguish whether neuronal injury was caused by viral infection or by the immune system response, a novel tissue culture model for WNV infection was established in neurons derived from embryonic stem (ES) cells. Undifferentiated ES cells were relatively resistant to WNV infection. After differentiation, ES cells expressed neural antigens, acquired a neuronal phenotype, and became permissive for WNV infection. Within 48 h of exposure to an exceedingly low multiplicity of infection (5 × 10−4), 50% of ES cell-derived neurons became infected, producing nearly 107PFU of infectious virus per ml, and began to die by an apoptotic mechanism. The establishment of a tractable virus infection model in ES cell-derived neurons facilitates the study of the molecular basis of neurotropism and the mechanisms of viral and immune-mediated neuronal injury after infection by WNV or other neurotropic pathogens.
Multispecific Vaccine-Induced Mucosal Cytotoxic TLymphocytes Reduce Acute-Phase Viral Replication but Fail inLong-Term Control of Simian Immunodeficiency VirusSIVmac239
Authors: Vogel Thorsten U. , Reynolds Matthew R. , Fuller Deborah H. , Vielhuber Kathy , Shipley Tim , Fuller James T. , Kunstman Kevin J. , Sutter Gerd , Marthas Marta L. , Erfle Volker , Wolinsky Steven M. , Wang Chenxi , Allison David B. , Rud Erling W. , Wilson Nancy , Montefiori David , Altman John D. , Watkins David I.
Published: November 2003

Given the current difficulties generating vaccine-induced neutralizing antibodies to human immunodeficiency virus (HIV), the focus of the vaccine community has shifted toward creating cytotoxic-T-lymphocyte (CTL)-based vaccines. Recent reports of CTL-based vaccine trials in macaques challenged with simian/human immunodeficiency virus SHIV-89.6P have supported the notion that such vaccines can ameliorate the course of disease. However, almost all of these studies included Env as an immunogen and since SHIV-89.6P is sensitive to neutralizing antibodies it is difficult to determine the mechanism(s) of protection. Consequently, SHIV-89.6P challenge of macaques may be a poor model for determining vaccine efficacy in humans. To ascertain the effect of vaccine-induced multispecific mucosal CTL, in the absence of Env-specific antibody, on the control of an immunodeficiency virus challenge, we vaccinated Mamu-A*01+macaques with constructs encoding a combination of CTL epitopes and full-length proteins (Tat, Rev, and Nef) by using a DNA prime/recombinant modified vaccinia virus Ankara (rMVA) boost regimen. The vaccination induced virus-specific CTL and CD4+helper T lymphocytes with CTL frequencies as high as 20,000/million peripheral blood mononuclear cells. The final rMVA vaccination, delivered intravenously, engendered long-lived mucosal CTL. At 16 weeks after the final rMVA vaccination, the vaccinees and naive, Mamu-A*01+controls were challenged intrarectally with SIVmac239. Massive early anamnestic cellular immune responses controlled acute-phase viral replication; however, the three vaccinees were unable to control virus replication in the chronic phase. The present study suggests that multispecific mucosal CTL, in the absence of neutralizing antibodies, can achieve a modicum of control over early viral replication but are unable to control chronic-phase viral replication after a high-dose mucosal challenge with a pathogenic simian immunodeficiency virus.
AlphaInterferon Inhibits Human T-Cell Leukemia Virus Type 1 Assembly byPreventing Gag Interaction withRafts
Authors: Feng Xuan , Vander Heyden Nancy , Ratner Lee
Published: November 2003

Alpha-2a
interferon (IFN-α2a) has beneficial clinical effects on human
T-cell leukemia virus type 1 (HTLV-1) infection, but its antiviral
mechanism of action is unknown. Antiviral effects of IFN-α2a
were studied in 293T cells expressing HTLV-1 proviral DNA and in
HTLV-1-infected cells (HOS/PL, MT2, and HUT102). In 293T cells, an
50% inhibitory concentration of 10 U of
IFN-α2a/ml was determined by p19 antigen ELISA. Analysis of
IFN-treated cells demonstrated no defect in viral protein synthesis but
did show a decrease in the level of released virus, as determined by
immunoblot assays. Electron microscopy studies of IFN-treated cells
revealed neither a defect in the site of virus budding nor tethering of
virus particles at the plasma membrane, thus arguing against an effect
on virus release. Cell fractionation studies and confocal microscopy
showed no effect of IFN on Gag association with membranes. However, the
level of Gag association with lipid rafts was decreased, suggesting a
role of IFN in inhibiting HTLV-1
assembly.
DeNovo Infection with Rhesus Monkey Rhadinovirus Leads to theAccumulation of Multiple Intranuclear Capsid Species during LyticReplication but Favors the Release of Genome-ContainingVirions
Authors: O'Connor Christine M. , Damania Blossom , Kedes Dean H.
Published: November 2003

Rhesus
monkey rhadinovirus (RRV) is one of the closest phylogenetic relatives
to the human pathogen Kaposi's sarcoma-associated herpesvirus
(KSHV), yet it has the distinct experimental advantage of entering
efficiently into lytic replication and growing to high titers in
culture. RRV therefore holds promise as a potentially attractive model
with which to study gammaherpesvirus structure and assembly. We have
isolated RRV capsids, determined their molecular composition, and
identified the genes encoding five of the main capsid structural
proteins. Our data indicate that, as with other herpesviruses, lytic
infection with RRV leads to the synthesis of three distinct
intranuclear capsid species. However, in contrast to the inefficiency
of KSHV maturation following reactivation from latently infected B-cell
lines (K. Nealon, W. W. Newcomb, T. R. Pray,
C. S. Craik, J. C. Brown, and D. H.
Kedes, J. Virol. 75:2866-2878, 2001), de novo infection of
immortalized rhesus fibroblasts with RRV results in the release of high
levels of infectious virions with genome-containing C capsids at their
center. Together, our findings argue for the use of RRV as a powerful
model with which to study the structure and assembly of
gammaherpesviruses and, specifically, the human
rhadinovirus,KSHV.
Long-Term Follow-Up of Incomplete Stent Apposition in Patients Who Received Sirolimus-Eluting Stent for De Novo Coronary Lesions
Authors: Degertekin Muzaffer , Serruys Patrick W. , Tanabe Kengo , Lee Chi Hang , Sousa J. Edouardo , Colombo Antonio , Morice Marie-Claude , Ligthart Jurgen M.R. , de Feyter Pim J.
Published: November 2003

Background—

Incomplete stent apposition (ISA) has been previously documented after sirolimus-eluting stent (SES) implantation. The aim of this study was to investigate the long-term intravascular ultrasound (IVUS) findings of ISA in patients who received SES.

Methods and Results—

A total of 13 patients who received SES and showed ISA at follow-up IVUS (follow-up I) were investigated. IVUS was performed on all of these patients 12 months later (follow-up II). Quantitative ISA area measurement was also performed at follow-up I and II. No vascular remodeling was observed in the vessel segment with ISA; external elastic membrane area was 19.4±6.6 versus 19.5±6.4 mm
2
at follow-up I and II, respectively. There was also no significant change in external elastic membrane area between vessel segment with ISA and without ISA (+1.5% versus −3.0%, respectively;
P
=0.27) at late follow-up. The ISA area, either including (2.5±1.7 versus 3.8±6.3 mm
2
;
P
=NS) or excluding (2.5±1.8 versus 2.4±1.7 mm
2
;
P
=NS) a single patient with aneurysm formation, was not significantly different between follow-up I and II. One patient manifested a coronary aneurysm in the stented segment at late follow-up that was probably present at the initial follow-up but masked by thrombus. It was successfully treated with a covered stent. All patients were asymptomatic, and no patient experienced late thrombotic occlusion.

Conclusions—

Vessel dimensions and area of ISA did not change over time, except for 1 coronary aneurysm that became apparent. ISA after implantation of a SES was not associated with adverse events at late follow-up.
Replacement of Connexin40 by Connexin45 in the Mouse
Authors: Alcoléa Sébastien , Jarry-Guichard Thérèse , de Bakker Jacques , Gonzàlez Daniel , Lamers Wouter , Coppen Steven , Barrio Luis , Jongsma Habo , Gros Daniel , van Rijen Harold
Published: November 2003

Gap junction channels, required for the propagation of cardiac impulse, are intercellular structures composed of connexins (Cx). Cx43, Cx40, and Cx45 are synthesized in the cardiomyocytes, and each of them has a unique cardiac expression pattern. Cx40 knock-in Cx45 mice were generated to explore the ability of Cx45 to replace Cx40, and to assess the functional equivalence of these two Cxs that are both expressed in the conduction system. ECGs revealed that the consequences resulting from the biallelic replacement of Cx40 by Cx45 were an increased duration of the P wave, and a prolonged and fractionated QRS complex. Epicardial mapping indicated that the conduction velocities (CV) in the right atrium and the ventricular myocardium, as well as conduction through the AV node, were unaffected. The significant reduction of the CV in the left atrium would be the most likely cause of the P-wave lengthening. In the right ventricle, a changed and prolonged activation in sinus rhythm was found in homozygous mutant mice, which may explain the prolongation and splitting of the QRS complex. Electrical mapping of the His bundle branches revealed that this was due to slow conduction measured in the right branch. The CV in the left branch was unchanged. Therefore, in the absence of Cx40, the upregulation of Cx45 in the heart results in a normal impulse propagation in the right atrium, the AV node, and the left His bundle branch only.
Adenosine A
3
Receptor Activation Modulates the Capillary Endothelial Glycocalyx
Authors: Platts Steven H. , Duling Brian R.
Published: November 2003

The endothelial glycocalyx is a dynamic extracellular matrix composed of cell surface proteoglycans, glycoproteins, and adsorbed serum proteins that has been implicated in the regulation and modulation of capillary tube hematocrit, permeability, and hemostasis. High tissue adenosine levels have been shown to adversely affect microvascular function and tissue survival after an ischemic episode, and previous work in this laboratory has shown that adenosine causes arteriolar constriction and degranulation of mast cells via the A
3
receptor (A3AR). We hypothesized that adenosine exerts at least part of its effect through modification of the glycocalyx via the A3AR. We used an in vivo cremaster model (hamster and mouse) in which circulating plasma was labeled with a 70-kDa FITC-dextran, and the capillaries were examined before and after superfusion with varying concentrations of adenosine (or other vasoactive molecules). Measurements of the dextran exclusion from an endothelial cell surface layer and red cell separation from the endothelial cell surface were made for up to 30 minutes. Our data indicate that adenosine causes a rapid and profound decrease in the ability of the glycocalyx to exclude dextran but only affects red blood cell exclusion at pharmacological levels. Knockout mice deficient in the A3AR were completely protected from glycocalyx changes attributable to adenosine. These data show a potential link between a known vasoactive tissue metabolite, adenosine, and regulation of the glycocalyx, which may be important during (patho)physiological changes in microvascular function during inflammatory insults.
Side of Brain Infarction and Long-Term Risk of Sudden Death in Patients With Symptomatic Carotid Disease
Authors: Algra Ale , Gates Peter C. , Fox Allan J. , Hachinski Vladimir , Barnett Henry J.M.
Published: November 2003

Background and Purpose—

Current publications suggest increased risk of sudden death in experimental animals with acute right insular lesions and in patients with recent right-sided brain infarction, particularly if the insula is involved.

Methods—

Using 3 different time definitions, we related long-term risk of sudden death to presence and side of brain infarction on the baseline brain scan and handedness in 2885 patients with symptomatic carotid disease.

Results—

In 1295 patients without brain infarction, 5-year risk of sudden death was 5.3% (24-hour definition); in those with left-sided infarction (n=471), 8.8%; in those with right-sided infarction (n=477), 6.0%; and in those with bilateral infarction (n=535), 9.7%. After accounting for differences of other risk factors (eg, previous myocardial infarction) in Cox regression, adjusted hazard ratios (HRs) compared with no infarction were as follows: left-sided HR, 1.45 (95% confidence interval [CI], 1.00 to 2.10); right-sided HR, 0.96 (95% CI, 0.62 to 1.47); and bilateral HR, 1.40 (95% CI, 0.98 to 2.00). Insular infarction occurred in 41 patients; none died suddenly. Left-handed or ambidextrous patients (n=183) had a lower risk of sudden death than right-handers; the adjusted HR for left-handed or ambidextrous patients was 0.24 (95% Cl, 0.07 to 0.70). These results were essentially the same for the 10- and 60-minute definitions of sudden death.

Conclusions—

In the long-term, left-sided, not right-sided, brain infarction is associated with increased risk of sudden death. Left-handed or ambidextrous patients have a lower risk of sudden death than right-handed patients, suggesting a role for the brain.
Leviticus 16 Als Mitte Der Tora
Authors: Rendtorff Rolf
Published: November 2003

In jüngster Zeit ist das Buch Leviticus in den Blickpunkt des exegetischen Interesses gerückt. Vielfach wird es innerhalb des Pentateuch als dessen Mitte betrachtet. Dabei richtet sich das besondere Interesse auf das Kapitel 16, das in formaler und inhaltlicher Hinsicht eine Sonderstellung einnimmt. Die Opfergesetzgebung kommt erst mit der jährlichen Sühnehandlung am jom hakkippurim zu ihrem entscheidenden Abschluß. Aber auch von den "Unreinheiten" oder "Verunreinigungen," von denen in Kapp. 11–15 vielfältig die Rede ist, werden die Israeliten durch die Riten dieses Tages gereinigt. So kann man Leviticus 16 geradezu als "Mitte der Tora" bezeichnen.
Seeing Solomon's Palanquin (Song of Songs 3:6-11)
Authors: Exum J. Cheryl
Published: November 2003

Song 3:6-11 shares distinctive poetic features with the rest of the Song of Songs, such as the impression of immediacy, the conjuring up of the loved one, the blurring of distinctions between past and present, and the address to an audience that includes the reader. This pericope is constructed in such a way as to bring a luxurious conveyance bearing Solomon (the male lover in his royal guise) from the furthest imaginable horizon, the wilderness, closer and closer to the speaker who describes the procession, and through whose eyes we perceive the sight in greater and greater detail. The poetic analysis sheds light on three debated questions in Song of Songs interpretation: (1) who is the speaker in these verses?, (2) who or what is coming up from the wilderness—a person or an object?, (3) do these verses describe a moving means of transport or a fixed structure?