bluuebunny/crossref_metadata_2025 huggingface dataset:
Pneumolysin-Induced Complement Depletion during Experimental Pneumococcal Bacteremia
Authors: Alcantara Rosemarie B. , Preheim Laurel C. , Gentry-Nielsen Martha J.
Published: July 2002

To quantify complement depletion by pneumolysin during
Streptococcus pneumoniae
bacteremia, cirrhotic and control rats were infected intravenously with one of three isogenic mutant strains of
S. pneumoniae
expressing different forms of pneumolysin. Outcome measures included clearance of the organisms from the bloodstream, alterations in 50% serum hemolytic complement (CH
50
) activity and complement C3 levels during infection, and serum opsonic capacity at 18 h postinfection. Cirrhotic rats had significantly lower CH
50
and C3 levels than control rats, both before and after infection. However, initial complement levels did not predict bacterial load after 18 h of infection. Changes in CH
50
and C3 levels over the 18-h period correlated with numbers of H+C+ but not H+C− or PLY− organisms in the bloodstream at 18 h postinfection. The sera of cirrhotic rats infected with the H+C+ strain had significantly decreased levels of C3 and showed significantly lower opsonizing activity for
S. pneumoniae
than sera from H+C+-infected control rats. These studies suggest that under limiting concentrations of complement, the expression of pneumolysin by pneumococci has a significant, negative effect on serum complement levels and reduces serum opsonic activity.
Relationship of Anti-Lewis x and Anti-Lewis y Antibodies in Serum Samples from Gastric Cancer and Chronic Gastritis Patients toHelicobacter pylori-Mediated Autoimmunity
Authors: Heneghan Michael A. , McCarthy Ciaran F. , Janulaityte Daiva , Moran Anthony P.
Published: July 2002

Lewis (Le) antigens have been implicated in the pathogenesis of atrophic gastritis and gastric cancer in the setting ofHelicobacter pyloriinfection, andH. pylori-induced anti-Le antibodies have been described that cross-react with the gastric mucosa of both mice and humans. The aim of this study was to examine the presence of anti-Le antibodies in patients withH. pyloriinfection and gastric cancer and to examine the relationships between anti-Le antibody production, bacterial Le expression, gastric histopathology, and host Le erythrocyte phenotype. Anti-Le antibody production andH. pyloriLe expression were determined by enzyme-linked immunosorbent assay, erythrocyte Le phenotype was examined by agglutination assays, and histology was scored blindly. Significant levels of anti-Lexantibody (P< 0.0001, T = 76.4, DF = 5) and anti-Leyantibody (P< 0.0001, T = 73.05, DF = 5) were found in the sera of patients with gastric cancer and otherH. pylori-associated pathology compared withH. pylori-negative controls. Following incubation of patient sera with synthetic Le glycoconjugates, anti-Lexand -Leyautoantibody binding was abolished. The degree of the anti-Lexand -Leyantibody response was unrelated to the host Le phenotype but was significantly associated with the bacterial expression of Lex(r= 0.863,r2= 0.745,P< 0.0001) and Ley(r= 0.796,r2= 0.634,P< 0.0001), respectively. Collectively, these data suggest that anti-Le antibodies are present in most patients withH. pyloriinfection, including those with gastric cancer, that variability exists in the strength of the anti-Le response, and that this response is independent of the host Le phenotype but related to the bacterial Le phenotype.
Lymphocyte Adhesion toCandida albicans
Authors: Forsyth Christopher B. , Mathews Herbert L.
Published: July 2002

Adherence of lymphocytes to the fungus is the first step in the direct lymphocyte-mediated antifungal effect againstCandida albicans. In this study we identified macrophage-1 antigen (Mac-1) (CD11b/CD18, αM/β2) as the lymphocyte surface structure responsible for the adhesion of activated lymphocytes to the hyphal form of the fungus. Antibodies specific for epitopes of the α-subunit (CD11b) and the β2-subunit (CD18) of Mac-1 were shown to completely eliminate lymphocyte adhesion toC. albicanshyphae. Lymphocyte adhesion toC. albicanswas also inhibited significantly by known ligands of Mac-1, including the extracellular matrix proteins laminin and fibrinogen, as well as engineered peptides containing arginine-glycine-aspartic acid sequences and the disintegrin echistatin.N-Acetyl-d-glucosamine and β-glucan, which inhibit Mac-1-mediated adhesion to the yeast, blocked lymphocyte adhesion to hyphae. NIH 3T3 fibroblast transfectants expressing human CD11b/CD18 bound toC. albicans, and their binding was inhibited by antibodies specific for CD11b/CD18. Finally, antibodies specific for CD11b/CD18 effectively inhibited the capacity of activated lymphocytes to have an antifungal effect against hyphae. Our results clearly identify Mac-1 (CD11b/CD18) as the lymphocyte surface structure that mediates activated lymphocyte adhesion toC. albicansand the resultant antifungal effect of the lymphocytes.
The Yeast Model for Batten Disease: Mutations in
btn1
,
btn2
, and
hsp30
Alter pH Homeostasis
Authors: Chattopadhyay Subrata , Muzaffar Neda E. , Sherman Fred , Pearce David A.
Published: July 2002

The
BTN1
gene product of the yeast
Saccharomyces cerevisiae
is 39% identical and 59% similar to human CLN3, which is associated with the neurodegenerative disorder Batten disease. Furthermore,
btn1
-Δ strains have an elevated activity of the plasma membrane H
+
-ATPase due to an abnormally high vacuolar acidity during the early phase of growth. Previously, DNA microarray analysis revealed that
btn1
-Δ strains compensate for the altered plasma membrane H
+
-ATPase activity and vacuolar pH by elevating the expression of the two genes
HSP30
and
BTN2
. We now show that deletion of either
HSP30
or
BTN2
in either
BTN1
+
or
btn1
-Δ strains does not alter vacuolar pH but does lead to an increased activity of the vacuolar H
+
-ATPase. Deletion of
BTN1
,
BTN2
, or
HSP30
does not alter cytosolic pH but diminishes pH buffering capacity and causes poor growth at low pH in a medium containing sorbic acid, a condition known to result in disturbed intracellular pH homeostasis. Btn2p was localized to the cytosol, suggesting a role in mediating pH homeostasis between the vacuole and plasma membrane H
+
-ATPase. Increased expression of
HSP30
and
BTN2
in
btn1
-Δ strains and diminished growth of
btn1
-Δ,
hsp30
-Δ, and
btn2
-Δ strains at low pH reinforce our view that altered pH homeostasis is the underlying cause of Batten disease.
CTXφ Infection of
Vibrio cholerae
Requires the
tolQRA
Gene Products
Authors: Heilpern Andrew J. , Waldor Matthew K.
Published: July 2002

CTXφ is a lysogenic filamentous bacteriophage that encodes cholera toxin. Filamentous phages that infect
Escherichia coli
require both a pilus and the products of
tolQRA
in order to enter host cells. We have previously shown that toxin-coregulated pilus (TCP), a type IV pilus that is an essential
Vibrio cholerae
intestinal colonization factor, serves as a receptor for CTXφ. To test whether CTXφ also depends upon
tol
gene products to infect
V. cholerae
, we identified and inactivated the
V. cholerae tolQRAB
orthologues. The predicted amino acid sequences of
V. cholerae
TolQ, TolR, TolA, and TolB showed significant similarity to the corresponding
E. coli
sequences.
V. cholerae
strains with insertion mutations in
tolQ
,
tolR
, or
tolA
were reduced in their efficiency of CTXφ uptake by 4 orders of magnitude, whereas a strain with an insertion mutation in
tolB
showed no reduction in CTXφ entry. We could detect CTXφ infection of TCP
−
V. cholerae
, albeit at very low frequencies. However, strains with mutations in both
tcpA
and either
tolQ
,
tolR
, or
tolA
were completely resistant to CTXφ infection. Thus, CTXφ, like the
E. coli
filamentous phages, uses both a pilus and TolQRA to enter its host. This suggests that the pathway for filamentous phage entry into cells is conserved between host bacterial species.
The Autolytic Enzyme LytA of
Streptococcus pneumoniae
Is Not Responsible for Releasing Pneumolysin
Authors: Balachandran Priya , Hollingshead Susan K. , Paton James C. , Briles David E.
Published: July 2002

It was previously proposed that autolysin's primary role in the virulence of pneumococci was to release pneumolysin to an extracellular location. This interpretation came into question when pneumolysin was observed to be released in significant amounts from some pneumococci during log-phase growth, because autolysis was not believed to occur at this time. We have reexamined this phenomenon in detail for one such strain, WU2. This study found that the extracellular release of pneumolysin from WU2 was not dependent on autolysin action. A mutant lacking autolysin showed the same pattern of pneumolysin release as the wild-type strain. Addition of mitomycin C to a growing WU2 culture did not induce lysis, indicating the absence of resident bacteriophages that could potentially harbor
lytA
-like genes. Furthermore, release of pneumolysin was unaltered by growth in 2% choline, a condition which is reported to inactivate autolysin, as well as most known pneumococcal phage lysins. Profiles of total proteins in the cytoplasm and in the supernatant media supported the hypothesis that release of pneumolysin is independent of pneumococcal lysis. Finally, under some infection conditions, mutations in pneumolysin and autolysin had different effects on virulence.
Identification of the UDP-MurNAc-Pentapeptide:
l
-Alanine Ligase for Synthesis of Branched Peptidoglycan Precursors in
Enterococcus faecalis
Authors: Bouhss Ahmed , Josseaume Nathalie , Allanic David , Crouvoisier Muriel , Gutmann Laurent , Mainardi Jean-Luc , Mengin-Lecreulx Dominique , van Heijenoort Jean , Arthur Michel
Published: July 2002

Many species of gram-positive bacteria produce branched peptidoglycan precursors resulting from the transfer of various
l
-amino acids or glycine from amino acyl-tRNA to the ɛ-amino group of
l
-lysine. The UDP-MurNAc-pentapeptide:
l
-alanine ligase and alanyl-tRNA synthetase genes from
Enterococcus faecalis
were identified, cloned, and overexpressed in
Escherichia coli
. The purified enzymes were necessary and sufficient for tRNA-dependent addition of
l
-alanine to UDP-MurNAc-pentapeptide in vitro. The ligase belonged to the Fem family of proteins, which were initially identified genetically as factors essential for methicillin resistance in
Staphylococcus aureus
.
Membrane Interaction ofEscherichia coliHemolysin: Flotation and Insertion-Dependent Labeling by Phospholipid Vesicles
Authors: Hyland Caroline , Vuillard Laurent , Hughes Colin , Koronakis Vassilis
Published: July 2002

The 1,024-amino-acid acylated hemolysin ofEscherichia colisubverts host cell functions and causes cell lysis. Both activities require insertion of the toxin into target mammalian cell membranes. To identify directly the principal toxin sequences dictating membrane binding and insertion, we assayed the lipid bilayer interaction of native protoxin, stably active toxin, and recombinant peptides. Binding was assessed by flotation of protein-liposome mixtures through density gradients, and insertion was assessed by labeling with a photoactivatable probe incorporated into the target lipid bilayer. Both the active acylated hemolysin and the inactive unacylated protoxin were able to bind and also insert. Ca2+binding, which is required for toxin activity, did not influence the in vitro interaction with liposomes. Three overlapping large peptides were expressed separately. A C-terminal peptide including residues 601 to 1024 did not interact in either assay. An internal peptide spanning residues 496 to 831, including the two acylation sites, bound to phospholipid vesicles and showed a low level of insertion-dependent labeling. In vitro acylation had no effect on the bilayer interaction of either this peptide or the full-length protoxin. An N-terminal peptide comprising residues 1 to 520 also bound to phospholipid vesicles and showed strong insertion-dependent labeling, ca. 5- to 25-fold that of the internal peptide. Generation of five smaller peptides from the N-terminal region identified the principal determinant of lipid insertion as the hydrophobic sequence encompassing residues 177 to 411, which is conserved among hemolysin-related toxins.
Intervening Sequences in
rrl
Genes and Fragmentation of 23S rRNA in Genera of the Family
Enterobacteriaceae
Authors: Pronk Loes M. , Sanderson Kenneth E.
Published: July 2002

Intervening sequences (IVSs) in the
rrl
genes for 23S rRNA are transcribed but later removed by RNase III without religation during RNA processing, leading to fragmented rRNA. We examined about 240 strains of the family
Enterobacteriaceae
for presence of IVSs using PCR. No IVSs were detected in strains belonging to
Escherichia
,
Shigella
,
Enterobacter
,
Erwinia
,
Ewingella
,
Hafnia
,
Kluyvera
,
Morganella
,
Pantoea
, or
Serratia
. Previously unreported IVSs were detected in
Klebsiella oxytoca
,
Citrobacter amalonaticus
, and
Providencia stuartii
; previously reported IVSs are in species of
Salmonella
,
Proteus
,
Providencia
, and
Yersinia
. The sporadic distribution of IVSs indicates lateral genetic transfer of IVSs.
Involvement of H-NS in Transpositional Recombination Mediated by IS
1
Authors: Shiga Yasuyuki , Sekine Yasuhiko , Kano Yasunobu , Ohtsubo Eiichi
Published: July 2002

IS
1
, the smallest active transposable element in bacteria, encodes a transposase that promotes inter- and intramolecular transposition. Host-encoded factors, e.g., histone-like proteins HU and integration host factor (IHF), are involved in the transposition reactions of some bacterial transposable elements. Host factors involved in the IS
1
transposition reaction, however, are not known. We show that a plasmid with an IS
1
derivative that efficiently produces transposase did not generate miniplasmids, the products of intramolecular transposition, in mutants deficient in a nucleoid-associated DNA-binding protein, H-NS, but did generate them in mutants deficient in histone-like proteins HU, IHF, Fis, and StpA. Nor did IS
1
transpose intermolecularly to the target plasmid in the H-NS-deficient mutant. The
hns
mutation did not affect transcription from the indigenous promoter of IS
1
for the expression of the transposase gene. These findings show that transpositional recombination mediated by IS
1
requires H-NS but does not require the HU, IHF, Fis, or StpA protein in vivo. Gel retardation assays of restriction fragments of IS
1
-carrying plasmid DNA showed that no sites were bound preferentially by H-NS within the IS
1
sequence. The central domain of H-NS, which is involved in dimerization and/or oligomerization of the H-NS protein, was important for the intramolecular transposition of IS
1
, but the N- and C-terminal domains, which are involved in the repression of certain genes and DNA binding, respectively, were not. The SOS response induced by the IS
1
transposase was absent in the H-NS-deficient mutant strain but was present in the wild-type strain. We discuss the possibility that H-NS promotes the formation of an active IS
1
DNA-transposase complex in which the IS
1
ends are cleaved to initiate transpositional recombination through interaction with IS
1
transposase.
Transcriptional Response of
Pasteurella multocida
to Nutrient Limitation
Authors: Paustian Michael L. , May Barbara J. , Kapur Vivek
Published: July 2002

Bacteria often encounter environments where nutrient availability is limited, and they must adapt accordingly. To identify
Pasteurella multocida
genes that are differentially expressed during nutrient limitation, we utilized whole-genome microarrays to compare levels of gene expression during growth in rich and minimal media. Our analysis showed that the levels of expression of a total of 669 genes, representing approximately one-third of the genome, were detectably altered over the course of the experiment. A large number (
n
= 439) of genes, including those involved in energy metabolism, transport, protein synthesis, and binding, were expressed at higher levels in rich medium, suggesting that, upon exposure to a rich environment,
P. multocida
immediately begins to turn on many energy-intensive biosynthetic pathways or, conversely, turns these genes off when it is exposed to a nutrient-deficient environment. Genes with increased expression in minimal medium (
n
= 230) included those encoding amino acid biosynthesis and transport systems, outer membrane proteins, and heat shock proteins. Importantly, our analysis also identified a large number (
n
= 164) of genes with unknown functions whose expression was altered during nutrient limitation. Overall, the results of our study show that a wide repertoire of genes, many of which have yet to be functionally classified, undergo transcriptional regulation in
P. multocida
in response to growth in minimal medium and provide a strong foundation to investigate the transcriptional response of this multispecies pathogen to growth in a nutrient-limited environment.
The
tra
Region of the Conjugative Plasmid pIP501 Is Organized in an Operon with the First Gene Encoding the Relaxase
Authors: Kurenbach Brigitta , Grothe Dagmar , Farías María Eugenia , Szewzyk Ulrich , Grohmann Elisabeth
Published: July 2002

The
tra
genes
orf1
to
orf11
of pIP501 were shown to be transcribed as a single operon of 11.3 kb in
Enterococcus faecalis
by reverse transcription-PCR. The transcriptional start site of the
tra
mRNA was mapped at 110 bp upstream from the predicted TTG start codon of the first gene of the operon, the
traA
relaxase. The TraA protein (660 amino acids) and a C-terminally truncated version of the TraA protein (293 amino acids) were purified as fusions with glutathione
S
-transferase.
oriT
cleavage activity of both TraA proteins was demonstrated in vitro on supercoiled plasmid pVA2241 DNA containing

oriT
pIP501

. The activity of the DNA relaxase TraA is strictly dependent on the presence of Mg
2+
or Mn
2+
and is highest at temperatures of between 42 and 45°C.
Newly Identified Cytochrome
c
Oxidase Operon in the Nitrogen-Fixing Cyanobacterium
Anabaena
sp. Strain PCC 7120 Specifically Induced in Heterocysts
Authors: Jones Kathryn M. , Haselkorn Robert
Published: July 2002

Two operons have been cloned from
Anabaena
sp. strain PCC 7120 DNA, each of which encodes the three core subunits of distinct mitochondrial-type cytochrome
c
oxidases. The two operons are only 72 to 85% similar to one another at the nucleotide level in the most conserved subunit. One of these,
coxBACII
, is induced >20-fold in the middle to late stages of heterocyst differentiation. Analysis of green fluorescent protein reporters indicates that this operon is expressed specifically in proheterocysts and heterocysts. The other operon,
coxBACI
, is induced only 2.5-fold following nitrogen step-down and is expressed in all cells. Surprisingly, a disruption mutant of
coxAII
, the gene encoding subunit I of the heterocyst-specific oxidase, grows normally in the absence of combined nitrogen. It is likely that
coxBACI
and/or two other putative terminal oxidases present in the
Anabaena
sp. strain PCC 7120 genome are able to compensate for the loss of the heterocyst-specific oxidase in providing ATP for nitrogen fixation and maintaining a low oxygen level in heterocysts.
Rapid Identification of Yeasts in Positive Blood Cultures by a Multiplex PCR Method
Authors: Chang Hsein Chang , Leaw Shiang Ning , Huang Ay Huey , Wu Tsu Lan , Chang Tsung Chain
Published: July 2002

Yeasts are emerging as important etiological agents of nosocomial bloodstream infections. A multiplex PCR method was developed to rapidly identify clinically important yeasts that cause fungemia. The method amplified the internal transcribed spacer 1 (ITS1) region between the 18S and 5.8S rRNA genes and a specific DNA fragment within the ITS2 region of
Candida
albicans
. With this method,
C
.
albicans
produced two amplicons, whereas other species produced only one. Through sequence analysis, the precise lengths of the PCR products were found to be as follows:
C
.
glabrata
(482 or 483 bp),
C
.
guilliermondii
(248 bp),
C
.
parapsilosis
(229 bp),
C
.
albicans
(218 or 219 and 110 bp),
C
.
tropicalis
(218 bp),
Cryptococcus
neoformans
(201 bp), and
C
.
krusei
(182 bp). The PCR products could be effectively separated by disk polyacrylamide gel electrophoresis. The method was used to test 249 positive blood cultures (255 isolates), from which the following species (strain number) were isolated:
C
.
albicans
(128),
C
.
tropicalis
(51),
C
.
glabrata
(28),
C
.
parapsilosis
(23),
C.
neoformans
(9),
C
.
krusei
(5),
C
.
guilliermondii
(3), and other, minor species (8). The test sensitivity of the method was 96.9% (247 of 255 isolates). The eight minor species were either misidentified (one strain) or not identified (seven strains). From the time at which a positive bottle was found, the multiplex PCR could be completed within 8 h; the present method is simpler than any previously reported molecular method for the identification of blood yeasts.
Comparison of IsoCode STIX and FTA Gene Guard Collection Matrices as Whole-Blood Storage and Processing Devices for Diagnosis of Malaria by PCR
Authors: Zhong Kathleen J. Y. , Salas Carola J. , Shafer Robyn , Gubanov Alex , Gasser Robert A. , Magill Alan J. , Forney J. Russ , Kain Kevin C.
Published: July 2002

We compared two collection devices, IsoCode and FTA, with whole blood for the diagnosis of malaria by PCR (
n
= 100). Using whole blood as the reference standard, both devices were sensitive for the detection of single-species malaria infections by PCR (≥96%). However, the detection of mixed infections was suboptimal (IsoCode was 42% sensitive, and FTA was 63% sensitive).
Patterns of Changes in Human Immunodeficiency Virus Type 1 V3 Sequence Populations Late in Infection
Authors: Nelson Julie A. E. , Baribaud Frédéric , Edwards Terri , Swanstrom Ronald
Published: July 2002

We have used a V3-specific heteroduplex tracking assay (V3-HTA) with probes from two different human immunodeficiency virus type 1 (HIV-1) subtypes to examine the extent and pace of HIV-1 evolution late in infection. Twenty-four subjects with advanced HIV-1 infection (CD4+T-cell count, <100/μl) and stable viral loads were studied using blood plasma samples collected over a study period of approximately 9 months, during which time most of the subjects were treated with reverse transcriptase inhibitors. The V3-HTA patterns from the first and last time points were evaluated initially to determine the amounts of change in V3 sequence populations, which were primarily changes in abundance in preexisting sequence populations. Three of the 24 subjects had major changes (greater than 50% total change in the relative abundance of the sequence populations), 11 subjects had intermediate changes (10 to 50% total change), and 10 subjects had minimal changes (less than 10% total change). The average total amount of change was between two- and threefold greater in subjects with X4-like variants, although there was no correlation between average viral load and the presence of X4-like variants. V3-HTA patterns in monthly samples from 11 of the subjects were also compared. In two subjects, the amount of change exceeded 40% in a 1-month period. Overall, the pace of change in V3 populations varied between subjects and was not constant within a subject over time. Sequence analysis of the V3 variants showed that R5-like variants (not containing any X4-associated substitutions) continued to be maintained in three subjects in the presence of X4-like variants, indicating that X4 variants do not always outgrow R5 variants. The coreceptor usage of the V3 sequences from two subjects was determined using a cell fusion assay. One subject had an X4 variant that was maintained at a low level for at least 9 months, during which time the predominant variants were R5X4 (dualtropic), while in the second subject the reverse situation was observed. One of the dualtropic variants had a novel sequence motif in V3, suggesting another evolutionary pathway to altered tropism. These studies begin to probe the complexities and pace of V3 evolution in vivo, revealing dynamic patterns of change among multiple V3 sequence variants in a subset of subjects.
The Intact Retroviral Env Glycoprotein of Human Foamy Virus Is a Trimer
Authors: Wilk Thomas , de Haas Felix , Wagner Andrea , Rutten Twan , Fuller Stephen , Flügel Rolf M. , Löchelt Martin
Published: July 2002

Electron microscopy of negatively stained human foamy virus particles provides direct evidence for the trimeric nature of intact Env surface glycoproteins. Three-dimensional image reconstruction reveals that the Env trimer is a tapering spike 14 nm in length. The spikes were often arranged in hexagonal rings which shared adjacent Env trimers.
Coadministration of Gamma Interferon with DNA Vaccine Expressing Woodchuck Hepatitis Virus (WHV) Core Antigen Enhances the Specific Immune Response and Protects against WHV Infection
Authors: Siegel Felix , Lu Mengji , Roggendorf Michael
Published: July 2002

DNA vaccinations are able to induce strong cellular immune responses in mice and confer protection against infectious agents. However, DNA vaccination of large animals appears to be less effective and requires repeated injections of large amounts of plasmid DNA. Enhancement of the efficiency of DNA vaccines may be achieved by coapplication of cytokine-expressing plasmids. Here we investigated, with woodchucks, whether coadministration of an expression plasmid for woodchuck gamma interferon (IFN-γ), pWIFN-γ, can improve DNA vaccination with woodchuck hepatitis virus core antigen (WHcAg). Animals were immunized with pWHcIm (a plasmid expressing WHcAg) alone or with a combination of pWHcIm and pWIFN-γ using a gene gun. Six weeks postimmunization, all animals were challenged with 105genome equivalents of woodchuck hepatitis virus (WHV). The antibody and lymphoproliferative immune responses to WHV proteins were determined after immunization and after challenge. Vaccination with pWHcIm and pWIFN-γ led to a pronounced lymphoproliferative response to WHcAg and protected woodchucks against subsequent virus challenge. Two of three animals vaccinated with pWHcIm alone did not show a detectable lymphoproliferative response to WHcAg. A low-level WHV infection occurred in these woodchucks after challenge, as WHV DNA was detectable in the serum by PCR. None of the pWHcIm-vaccinated animals showed an anti-WHcAg antibody response after DNA vaccination or an anamnestic response after virus challenge. Our results indicate that coadministration of the WIFN-γ gene with pWHcIm enhanced the specific cellular immune response and improved the protective efficacy of WHV-specific DNA vaccines.
Adenovirus Type 9 Fiber Knob Binds to the Coxsackie B Virus-Adenovirus Receptor (CAR) with Lower Affinity than Fiber Knobs of Other CAR-Binding Adenovirus Serotypes
Authors: Kirby Ian , Lord Rosemary , Davison Elizabeth , Wickham Thomas J. , Roelvink Peter W. , Kovesdi Imre , Sutton Brian J. , Santis George
Published: July 2002

The coxsackie B virus and adenovirus (Ad) receptor (CAR) functions as an attachment receptor for multiple Ad serotypes. Here we show that the Ad serotype 9 (Ad9) fiber knob binds to CAR with much reduced affinity compared to the binding by Ad5 and Ad12 fiber knobs as well as the knob of the long fiber of Ad41 (Ad41L). Substitution of Asp222 in Ad9 fiber knob with a lysine that is conserved in Ad5, Ad12, and Ad41L substantially improved Ad9 fiber knob binding to CAR, while the corresponding substitution in Ad5 (Lys442Asp) significantly reduced Ad5 binding. The presence of an aspartic acid residue in Ad9 therefore accounts, at least in part, for the reduced CAR binding affinity of the Ad9 fiber knob. Site-directed mutagenesis of CAR revealed that CAR residues Leu73 and Lys121 and/or Lys123 are critical contact residues, with Tyr80 and Tyr83 being peripherally involved in the binding interaction with the Ad5, Ad9, Ad12, and Ad41L fiber knobs. The overall affinities and the association and dissociation rate constants for wild-type CAR as well as Tyr80 and Tyr83 CAR mutants differed between the serotypes, indicating that their binding modes, although similar, are not identical.
The Leader Protein of Theiler's Virus Inhibits Immediate-Early Alpha/Beta Interferon Production
Authors: van Pesch Vincent , van Eyll Olivier , Michiels Thomas
Published: July 2002

Theiler's virus is a picornavirus responsible for a persistent infection of the central nervous system of the mouse, leading to a chronic demyelinating disease considered to be a model for multiple sclerosis. The leader (L) protein encoded by Theiler's virus is a 76-amino-acid-long peptide containing a zinc-binding motif. This motif is conserved in the L proteins of all cardioviruses, including encephalomyocarditis virus. The L protein of Theiler's virus was suggested to interfere with the alpha/beta interferon (IFN-α/β) response (W.-P. Kong, G. D. Ghadge, and R. P. Roos, Proc. Natl. Acad. Sci. USA 91:1796–1800, 1994). We show that expression of the L protein indeed inhibits the production of alpha/beta interferon by infected L929 cells. The L protein specifically inhibits the transcription of the IFN-α4 and IFN-β genes, which are known to be activated early in response to viral infection. Mutation of the zinc finger was sufficient to block the anti-interferon activity, outlining the importance of this motif in the L protein function. In agreement with the anti-interferon role of the L protein, a virus bearing a mutation in the zinc-binding motif was dramatically impaired in its ability to persist in the central nervous system of SJL/J mice.
Contribution of Vascular Endothelial Growth Factor in the Neovascularization Process during the Pathogenesis of Herpetic Stromal Keratitis
Authors: Zheng Mei , Deshpande Shilpa , Lee Sujin , Ferrara Napoleone , Rouse Barry T.
Published: July 2002

This report analyzes the role of vascular endothelial growth factor (VEGF)-induced angiogenesis in the immunoinflammatory lesion stromal keratitis induced by ocular infection with herpes simplex virus (HSV). Our results show that infection with replication-competent, but not mutant, viruses results in the expression of VEGF mRNA and protein in the cornea. This a rapid event, with VEGF mRNA detectable by 12 h postinfection (p.i.) and proteins detectable by 24 h p.i. VEGF production occurred both in the virus-infected corneal epithelium and in the underlying stroma, in which viral antigens were undetectable. In the stroma, VEGF was produced by inflammatory cells; these initially were predominantly polymorphonuclear leukocytes (PMN), but at later time points both PMN and macrophage-like cells were VEGF producers. In the epithelium, the major site of VEGF-expressing cells in early infection, the infected cells themselves were usually negative for VEGF. Similarly, in vitro infection studies indicated that the cells which produced VEGF were not those which expressed virus. Attesting to the possible role of VEGF-induced angiogenesis in the pathogenesis of herpetic stromal keratitis were experiments showing that VEGF inhibition with mFlt(1–3)-immunoglobulin G diminished angiogenesis and the severity of lesions after HSV infection. These observations are the first to evaluate VEGF-induced angiogenesis in the pathogenesis of stromal keratitis. Our results indicate that the control of angiogenesis represents a useful adjunct to therapy of herpetic ocular disease, an important cause of human blindness.
DDB2 Induces Nuclear Accumulation of the Hepatitis B Virus X Protein Independently of Binding to DDB1
Authors: Nag Alo , Datta Abhishek , Yoo Kyung , Bhattacharyya Dibyendu , Chakrabortty Amit , Wang Xinhi , Slagle Betty L. , Costa Robert H. , Raychaudhuri Pradip
Published: July 2002

The hepatitis B virus (HBV) X protein (HBx) is critical for the life cycle of the virus. HBx associates with several host cell proteins including the DDB1 subunit of the damaged-DNA binding protein DDB. Recent studies on the X protein encoded by the woodchuck hepadnavirus have provided correlative evidence indicating that the interaction with DDB1 is important for establishment of infection by the virus. In addition, the interaction with DDB1 has been implicated in the nuclear localization of HBx. Because the DDB2 subunit of DDB is required for the nuclear accumulation of DDB1, we investigated the role of DDB2 in the nuclear accumulation of HBx. Here we show that expression of DDB2 increases the nuclear levels of HBx. Several C-terminal deletion mutants of DDB2 that fail to bind DDB1 are able to associate with HBx, suggesting that DDB2 may associate with HBx independently of binding to DDB1. We also show that DDB2 enhances the nuclear accumulation of HBx independently of binding to DDB1, since a mutant that does not bind DDB1 is able to enhance the nuclear accumulation of HBx. HBV infection is associated with liver pathogenesis. We show that the nuclear levels of DDB1 and DDB2 are tightly regulated in hepatocytes. Studies with regenerating mouse liver indicate that during late G
1
phase the nuclear levels of both subunits of DDB are transiently increased, followed by a sharp decrease in S phase. Taken together, these results suggest that DDB1 and DDB2 would participate in the nuclear functions of HBx effectively only during the late-G
1
phase of the cell cycle.
In Vivo Inhibition of Anti-Hepatitis B Virus Core Antigen (HBcAg) Immunoglobulin G Production by HBcAg-Specific CD4+Th1-Type T-Cell Clones in a hu-PBL-NOD/SCID Mouse Model
Authors: Cao Tinghua , Meuleman Philip , Desombere Isabelle , Sällberg Matti , Leroux-Roels Geert
Published: July 2002

Hepatitis B virus (HBV) core antigen (HBcAg)-specific CD4+T-cell responses are believed to play an important role in the control of human HBV infection. In the present study, HBcAg-specific, HLA-DR13*-restricted CD4+Th1-type T-cell clones were generated which secreted both gamma interferon and tumor necrosis factor alpha after in vitro antigen stimulation. These HBcAg-specific CD4+Th1-type T cells were able to lyse HBc peptide-loaded Epstein-Barr virus-transformed lymphoblastoid target cells in vitro. To examine whether these HLA-DR13*-restricted human CD4+Th1 T cells also display the same cytotoxic effects in vivo, we transferred peripheral blood leukocytes (PBL) derived from HBV-infected donors or an HBV-naı̈ve donor sharing the DR13*, together with the HBcAg-specific CD4+Th1-type T cells and HBcAg, directly into the spleen of optimally conditioned Nod/LtSz-Prkdcscid/Prkdcscid(NOD/SCID) mice. The production of both secondary anti-HBc-immunoglobulin G (anti-HBc-IgG) and primary HBcAg-binding IgM in hu-PBL-NOD/SCID mice was drastically inhibited by HBcAg-specific CD4+Th1-type T cells. No inhibition was observed when CD4+Th1 cells and donor PBL did not share an HLA-DR13. These results suggest that HBcAg-specific CD4+Th1 T cells may be able to lyse HBcAg-binding, or -specific, B cells that have taken up and presented HBcAg in a class II-restricted manner. Thus, HBcAg-specific CD4+Th1-type T cells can modulate the function and exert a regulatory role in deleting HBcAg-binding, or -specific, human B cells in vivo, which may be of importance in controlling the infection.
Synthesis of Ferrocenyl-Substituted Heterocycles: The Beneficial Effect of the Microwave Irradiation
Authors: Puciová Monika , Ertl Peter , Toma Štefan
Published: July 2002

The synthesis of ferrocenyl-substituted thiophenes, furans, pyrroles, pyrimidine and pyrazole has been studied. 2-Ferrocenylpyrroles were prepared from ferrocenyl ketoximes and acetylene in DMSO - KOH mixture whereas 3-chloro-3-ferrocenylacrylaldehydes and thioglycolic or glycolic acids were the starting materials for the synthesis of the thiophene and furan derivatives. The yields were significantly enhanced when the reactions were carried out in a microwave oven. The lower stability of 2-ferrocenylfuran in comparison with 2-ferrocenylthiophene is discussed on the basis of semiempirical quantum chemistry calculations.
Body temperature regulation in the amphisbaenian Trogonophis wiegmanni
Authors: López Pilar , Civantos Emilio , Martín José
Published: July 2002

We studied the thermal ecology of the amphisbaenian Trogonophis wiegmanni at the Chafarinas Islands (North Africa). We aimed to evaluate the extent of thermoregulation in this fossorial amphisbaenian by analyzing the relationships between environmental available operative (Te) and body (Tb) temperatures of active individuals found under stones. Amphisbaenians are typical thigmotherms that obtain heat through contact with soil and, thus, Tb was closely correlated to Te under stones. However, the comparison of Tb with Tes available in the study area indicated that Tb deviated less from the set-point range of preferred temperatures than would result from a random response, which is indicative of behavioral temperature regulation. Measurements of Te under rocks selected by T. wiegmanni deviated significantly less from the range of preferred temperatures than Te beneath available rocks. This suggests that amphisbaenians occupied rocks with or when thermal properties were suitable for maintaining their preferred Tb. We found a bimodal pattern of Tb during the day, with amphisbaenians being active at higher Tb during the afternoon than in the morning. This did not reflect changes in the thermal environment, but was presumably a voluntary selection pattern, as indicated by similar results obtained in thermal gradients in a previous study. Also, juveniles had higher Tb than adults, but this might be a biophysical effect of differences in body size and heating rates. We conclude that amphisbaenians seem capable of regulating body temperature to an extent that comparable with epigeal diurnal lizards.
Egg size as a predictor of nutrient composition of eggs and neonates of Canada Geese (Branta canadensis interior) and Lesser Snow Geese (Chen caerulescens caerulescens)
Authors: Badzinski Shannon S , Ankney C Davison , Leafloor James O , Abraham Kenneth F
Published: July 2002

Fresh and pipped eggs were collected to provide data on nutrient composition of eggs and neonates, respectively, of Canada Geese (Branta canadensis interior) and Lesser Snow Geese (Chen caerulescens caerulescens). We sought to determine how well a commonly used and simple index like estimated egg volume or "egg size" predicted egg composition and neonate characteristics including body composition, structural size, and digestive-organ mass. For both species, egg constituents were positively correlated with egg size, but relations for Canada Geese consistently had higher coefficients of determination than did those for Lesser Snow Geese. These differences suggest that there is more among-female variation in nutrient composition of Lesser Snow goose eggs relative to Canada Goose eggs. Most neonatal nutrient constituents were positively correlated with egg size in both species, but the relations between nutrient constituents and egg size were consistently stronger in Lesser Snow Geese than in Canada Geese. Several measures of structural size of neonates were positively correlated with egg size in both species, but egg size was a better predictor of neonate size for Lesser Snow Geese than for Canada Geese. Egg size was a relatively poor predictor of digestive-organ mass for both species. We hypothesize that the stronger relations between neonate quality and egg size in Lesser Snow Geese are a reflection of greater stabilizing selection for embryonic metabolic rates in species that nest at high latitudes and have a short incubation period. The fact that nutrient constituents of eggs were more strongly related to egg size than were the analogous constituents of neonates suggests that variation in metabolic rates of embryos limits the utility of egg size as an accurate and precise predictor of nutrient constituents in the two study species, but especially in Canada Geese.
SOME RIGOROUS RESULTS ON THE GROUND STATES OF THE FALICOV-KIMBALL MODEL
Authors: KENNEDY TOM
Published: July 2002

The Falicov-Kimball model consists of nuclei which are not allowed to hop and spinless electrons which can hop between nearest neighbor sites. There is an on-site interaction between electrons and nuclei. We consider the model in two dimensions with a large attractive potential. For the neutral model with densities between 1/4 and 1/2 we prove that the configuration of the nuclei in the ground state must consist of parallel lines of lattice sites which are either completely occupied by nuclei or completely free of nuclei. (The angle of the lines with respect to the lattice depends on the density. Some mild assumptions on the ground state are needed for this result.) For densities 1/3, 1/4 and 1/5 we prove that the ground state configuration of the nuclei is indeed that which had been conjectured [8]. For the nonneutral model we show that if the model is close to neutrality in the sense that both the electron and nuclear densities are close to 1/2, 1/3, 1/4 or 1/5 then the configuration of the nuclei in the ground state is close to the nuclear ground state for the neutral model with density 1/2, 1/3, 1/4 or 1/5.
HOLOGRAPHIC ENTROPY AND BRANE FRW DYNAMICS FROM AdS BLACK HOLE IN d5 HIGHER DERIVATIVE GRAVITY
Authors: NOJIRI SHIN'ICHI , ODINTSOV SERGEI D. , OGUSHI SACHIKO
Published: July 2002

Higher derivative bulk gravity (without Riemann tensor square term) admits AdS–Schwarzschild black hole as an exact solution. It is shown that induced brane geometry on such background is open, flat or closed FRW radiation dominated universe. Higher derivative terms contributions appear in the Hawking temperature, entropy and Hubble parameter via the redefinition of five-dimensional gravitational constant and AdS scale parameter. These higher derivative terms do not destroy the AdS-dual description of radiation represented by strongly-coupled CFT. The Cardy–Verlinde formula which expresses cosmological entropy as the square root from other parameters and entropies is derived in R2gravity. The corresponding cosmological entropy bounds are briefly discussed.
TRANSITION FROM BIEXCITONS TO ELECTRON-HOLE PLASMA IN PHOTOLUMINESCENCE PROPERTIES OF A GaAs/AlAs MULTIPLE-QUANTUM-WELL STRUCTURE
Authors: ICHIDA H. , TSUJI K. , MIZOGUCHI K. , NISHIMURA H. , NAKAYAMA M.
Published: July 2002

We report photoluminescence (PL) properties under various excitation-power conditions in a GaAs (15.0 nm)/AlAs(15.0 nm) multiple-quantum-well structure. we have clearly observed the PL bands from the biexciton and electron-hole plasma, and estimated the biexciton binding energy and the band-gap renormalization in the electron-hole plasma. The spectral change of the PL bands as a function of the excitation power demonstrates the transition from the biexciton to the electron-hole plasma under intense excitation conditions.
VESICLE TO MICELLE TRANSITION DRIVEN BY SURFACE SOLID-FLUID TRANSITION
Authors: NARAYANAN JANAKY , MENDES E. , MANOHAR C.
Published: July 2002

This paper reviews the solution behavior of cetyltrimethylammonium hydroxynaphthalene carboxylate (CTAHNC), which has the unique feature of undergoing a transition from vesicle to worm-like micellar phase in three different ways, namely, increase in temperature, addition of a surfactant and on shearing. Fluorescence anisotropy, NMR, rheology, small angle neutron scattering studies etc gave evidence of the vesicle-micelle transition. CTAHNC can be looked upon as a complex formed by two oppositely charged surfactants (CTA+ and HNC-). This ion pair effectively acts as a double-chain lipid and has a tendency to form vesicles. On increasing the temperature, and/or adding single chain surfactants of shearing, the complex dissociates which changes the curvature energy of the surface. This leads to a 'surface melting' that brings forth the vesicle-micelle transition.
BIRTH OF THE UNIVERSE AS ANTITUNNELLING FROM THE STRING PERTURBATIVE VACUUM
Authors: GASPERINI M.
Published: July 2002

The decay of the string perturbative vacuum, if triggered by a suitable, duality-breaking dilaton potential, can efficiently proceed via the parametric amplification of the Wheeler–De Witt wave function in superspace, and can appropriately describe the birth of our Universe as a quantum process of pair production from the vacuum.
BREAKDOWN OF THE FORWARD SCATTERING MODEL IN MgO(001)
Authors: CHASSÉ A. , NIEBERGALL L. , RENNERT P. , UHLIG I. , CHASSÉ T.
Published: July 2002

Typically, enhanced intensities are observed along low-index crystallographic directions of the crystal when Auger or photoelectrons with a kinetic energy of several hundred eV or more are emitted from atoms in a solid. This effect is a result of strong forward scattering of emitted electrons by overlying lattice atoms. Contrary to this image, a strong dip along the [110] direction has been found in the angular distribution curve of O-KLL Auger electrons of the MgO(001) surface, even though the kinetic energy of O-KLL Auger electrons is about 500 eV. The angular dependence of Auger (O-KLL, Mg-KLL) and photoelectrons (O1s) in MgO(001) is discussed and explained within a multiple scattering cluster model, respectively.
SEARCH FOR PATTERNS IN COMPRESSED TIME SERIES
Authors: PRATT KEVIN B. , FINK EUGENE
Published: July 2002

We describe a technique for fast compression of time series, indexing of compressed series, and retrieval of series similar to a given pattern. The compression procedure identifies "important" points of a series and discards the other points. We use the important points not only for compression, but also for indexing a database of time series. Experiments show the effectiveness of this technique for indexing of stock prices, weather data and electroencephalograms.
Power minimization in IC design
Authors: Pedram Massoud
Published: July 2002

Low power has emerged as a principal theme in today's electronics industry. The need for low power has caused a major paradigm shift in which power dissipation is as important as performance and area. This article presents an in-depth survey of CAD methodologies and techniques for designing low power digital CMOS circuits and systems and describes the many issues facing designers at architectural, logical, and physical levels of design abstraction. It reviews some of the techniques and tools that have been proposed to overcome these difficulties and outlines the future challenges that must be met to design low power, high performance systems.
BE VISION, A Package of IBM 7090 FORTRAN Programs to Draw Orthographic Views of Combinations of Plane and Quadric Surfaces
Authors: Weiss Ruth A.
Published: July 2002

BE VISION is a package of FORTRAN programs for drawing orthographic views of combinations of plane and quadric surfaces. As input, the package takes rectangular coordinate equations specifying the surfaces plus a three-angle specification of the viewing direction. Output is a drawing on the Stromberg Carlson 4020 Microfilm Recorder. Many views of one scene may be obtained simply by changing the viewpoint.

The various subroutines of the package and their functions are described in this paper. It also gives numerous examples of pictures that were produced by BE VISION. The package has been in use since April 1964.