bluuebunny/crossref_metadata_2025 huggingface dataset:
Free lines for homeomorphisms of the open annulus
Authors: Guillou Lucien
Published: December 2007

Let

H
H

be a homeomorphism of the open annulus

S
1

×

R

S^1 \times \textbf {R}

isotopic to the identity and let

h
h

be a lift of

H
H

to the universal cover

R

×

R

\textbf {R} \times \textbf {R}

without fixed point. Then we show that

h
h

admits a Brouwer line which is a lift of a properly imbedded line joining one end to the other in the annulus or

H
H

admits a free essential simple closed curve.
Constructing tilting modules
Authors: Kerner Otto , Trlifaj Jan
Published: December 2007

We investigate the structure of (infinite dimensional) tilting modules over hereditary artin algebras. For connected algebras of infinite representation type with Grothendieck group of rank

n
n

, we prove that for each

0
≤
i
>
n
−
1

0 \leq i > n-1

, there is an infinite dimensional tilting module

T
i

T_i

with exactly

i
i

pairwise non-isomorphic indecomposable finite dimensional direct summands. We also show that any stone is a direct summand in a tilting module. In the final section, we give explicit constructions of infinite dimensional tilting modules over iterated one-point extensions.
Equilibriums of some non-Hölder potentials
Authors: Hu Huyi
Published: December 2007

We consider one-sided subshifts

σ
\sigma

with some potential functions

φ
\varphi

which satisfy the Hölder condition everywhere except at a fixed point and its preimages. We prove that the systems have conformal measures

ν
\nu

and invariant measures

μ
\mu

absolutely continuous with respect to

ν
\nu

, where

μ
\mu

may be finite or infinite. We show that the systems

(
σ
,
μ
)

(\sigma , \mu )

are exact, and

μ
\mu

are weak Gibbs measures and equilibriums for

φ
\varphi

. We also discuss uniqueness of equilibriums and phase transition. These results can be applied to some expanding dynamical systems with an indifferent fixed point.
Zeta functions for analytic mappings, log-principalization of ideals, and Newton polyhedra
Authors: Veys Willem , Zúñiga-Galindo W.
Published: December 2007

In this paper we provide a geometric description of the possible poles of the Igusa local zeta function

Z

Φ

(
s
,

f

)

Z_{\Phi }(s,\mathbf {f})

associated to an analytic mapping

f

=

\mathbf {f}=

(

f

1

,
…
,

f

l

)

:
U
(
⊆

K

n

)
→

K

l

\left (f_{1},\ldots ,f_{l}\right ) :U(\subseteq K^{n})\rightarrow K^{l}

, and a locally constant function

Φ
\Phi

, with support in

U
U

, in terms of a log-principalizaton of the

K

[
x
]

−

K\left [x \right ] -

ideal

I

f

=

(

f

1

,
…
,

f

l

)

\mathcal {I}_{\mathbf {f}}=\left (f_{1},\ldots ,f_{l}\right )

. Typically our new method provides a much shorter list of possible poles compared with the previous methods. We determine the largest real part of the poles of the Igusa zeta function, and then as a corollary, we obtain an asymptotic estimation for the number of solutions of an arbitrary system of polynomial congruences in terms of the log-canonical threshold of the subscheme given by

I

f

\mathcal {I}_{\mathbf {f}}

. We associate to an analytic mapping

f
\boldsymbol {f}

=
=

(

f

1

,
…
,

f

l

)

\left (f_{1},\ldots ,f_{l}\right )

a Newton polyhedron

Γ

(
f
)

\Gamma \left (\boldsymbol {f}\right )

and a new notion of non-degeneracy with respect to

Γ

(
f
)

\Gamma \left (\boldsymbol {f}\right )

. The novelty of this notion resides in the fact that it depends on one Newton polyhedron, and Khovanskii’s non-degeneracy notion depends on the Newton polyhedra of

f

1

,
…
,

f

l

f_{1},\ldots ,f_{l}

. By constructing a log-principalization, we give an explicit list for the possible poles of

Z

Φ

(
s
,

f

)

Z_{\Phi }(s,\mathbf {f})

,

l
≥
1

l\geq 1

, in the case in which

f

\mathbf {f}

is non-degenerate with respect to

Γ

(
f
)

\Gamma \left (\boldsymbol {f}\right )

.
Equivalence of quotient Hilbert modules–II
Authors: Douglas Ronald , Misra Gadadhar
Published: December 2007

For any open, connected and bounded set

Ω
⊆

C

m

\Omega \subseteq \mathbb {C}^m

, let

A

\mathcal A

be a natural function algebra consisting of functions holomorphic on

Ω
\Omega

. Let

M

\mathcal M

be a Hilbert module over the algebra

A

\mathcal A

and let

M

0

⊆

M

\mathcal M_0\subseteq \mathcal M

be the submodule of functions vanishing to order

k
k

on a hypersurface

Z

⊆
Ω

\mathcal Z \subseteq \Omega

. Recently the authors have obtained an explicit complete set of unitary invariants for the quotient module

Q

=

M

⊖

M

0

\mathcal Q=\mathcal M \ominus \mathcal M_0

in the case of

k
=
2

k=2

. In this paper, we relate these invariants to familiar notions from complex geometry. We also find a complete set of unitary invariants for the general case. We discuss many concrete examples in this setting. As an application of our equivalence results, we characterise certain homogeneous Hilbert modules over the bi-disc algebra.
Theory of valuations on manifolds, III. Multiplicative structure in the general case
Authors: Alesker Semyon , Fu Joseph
Published: December 2007

This is the third part of a series of articles where the theory of valuations on manifolds is constructed. In the second part of this series the notion of a smooth valuation on a manifold was introduced. The goal of this article is to put a canonical multiplicative structure on the space of smooth valuations on general manifolds, thus extending some of the affine constructions from the first author’s 2004 paper and, from the first part of this series.
Profinite and pro-𝑝 completions of Poincaré duality groups of dimension 3
Authors: Kochloukova Dessislava , Zalesskii Pavel
Published: December 2007

We establish some sufficient conditions for the profinite and pro-ppcompletions of an abstract groupGGof typeFPmFP_m(resp. of finite cohomological dimension, of finite Euler characteristic) to be of typeFPmFP_mover the fieldFp\mathbb {F}_pfor a fixed natural primepp(resp. of finite cohomologicalpp-dimension, of finite Eulerpp-characteristic). We apply our methods for orientable Poincaré duality groupsGGof dimension 3 and show that the pro-ppcompletionG^p\widehat {G}_pofGGis a pro-ppPoincaré duality group of dimension 3 if and only if every subgroup of finite index inG^p\widehat {G}_phas deficiency 0 andG^p\widehat {G}_pis infinite. Furthermore ifG^p\widehat {G}_pis infinite but not a Poincaré duality pro-ppgroup, then either there is a subgroup of finite index inG^p\widehat {G}_pof arbitrary large deficiency orG^p\widehat {G}_pis virtuallyZp\mathbb {Z}_p. Finally we show that if every normal subgroup of finite index inGGhas finite abelianization and the profinite completionG^\widehat {G}ofGGhas an infinite Sylowpp-subgroup, thenG^\widehat {G}is a profinite Poincaré duality group of dimension 3 at the primepp.
Approximation theorems for the propagators of higher order abstract Cauchy problems
Authors: Liang Jin , Nagel Rainer , Xiao Ti-Jun
Published: December 2007

In this paper, we present two quite general approximation theorems for the propagators of higher order (in time) abstract Cauchy problems, which extend largely the classical Trotter-Kato type approximation theorems for strongly continuous operator semigroups and cosine operator functions. Then, we apply the approximation theorems to deal with the second order dynamical boundary value problems.
Frobenius distributions of Drinfeld modules over finite fields
Authors: Gekeler Ernst-Ulrich
Published: December 2007

We express the weighted class number of Drinfeld

A
A

-modules of rank two with given characteristic polynomial over the finite field

F

p

=
A

/

p

{\mathbb {F}} _{\mathfrak {p}}=A/{\mathfrak {p}}

(

p

∈
Spec
⁡
A

({\mathfrak {p}} \in \operatorname {Spec}A

, where

A
=

F

q

[
T
]
)

A=\mathbb {F} _q[T])

as an infinite product of local terms. Some auxiliary results of independent interest about characteristic polynomials of Drinfeld modules are given.
Caveolin-1 and -2 Interact with Connexin43 and Regulate Gap Junctional Intercellular Communication in Keratinocytes
Authors: Langlois Stéphanie , Cowan Kyle N. , Shao Qing , Cowan Bryce J. , Laird Dale W.
Published: December 2007

Connexin43 (Cx43) has been reported to interact with caveolin (Cav)-1, but the role of this association and whether other members of the caveolin family bind Cx43 had yet to be established. In this study, we show that Cx43 coimmunoprecipitates and colocalizes with Cav-1 and Cav-2 in rat epidermal keratinocytes. The colocalization of Cx43 with Cav-1 was confirmed in keratinocytes from human epidermis in vivo. Our mutation and Far Western analyses revealed that the C-terminal tail of Cx43 is required for its association with Cavs and that the Cx43/Cav-1 interaction is direct. Our results indicate that newly synthesized Cx43 interacts with Cavs in the Golgi apparatus and that the Cx43/Cavs complex also exists at the plasma membrane in lipid rafts. Using overexpression and small interfering RNA approaches, we demonstrated that caveolins regulate gap junctional intercellular communication (GJIC) and that the presence of Cx43 in lipid raft domains may contribute to the mechanism modulating GJIC. Our results suggest that the Cx43/Cavs association occurs during exocytic transport, and they clearly indicate that caveolin regulates GJIC.
Fitness of
Streptococcus pneumoniae
Fluoroquinolone-Resistant Strains with Topoisomerase IV Recombinant Genes
Authors: Balsalobre Luz , de la Campa Adela G.
Published: December 2007

The low prevalence of ciprofloxacin-resistant (Cp
r
)
Streptococcus pneumoniae
isolates carrying recombinant topoisomerase IV genes could be attributed to a fitness cost imposed by the horizontal transfer, which often implies the acquisition of larger-than-normal
parE
-
parC
intergenic regions. A study of the transcription of these genes and of the fitness cost for 24 isogenic Cp
r
strains was performed. Six first-level transformants were obtained either with PCR products containing the
parC
quinolone resistance-determining regions (QRDRs) of
S. pneumoniae
Cp
r
mutants with point mutations or with a PCR product that includes
parE
-QRDR-
ant
-
parC
-QRDR from a Cp
r
Streptococcus mitis
isolate. The latter yielded two strains, T6 and T11, carrying
parC
-QRDR and
parE
-QRDR-
ant
-
parC
-QRDR, respectively. These first-level transformants were used as recipients in further transformations with the
gyrA
-QRDR PCR products to obtain 18 second-level transformants. In addition, strain Tr7 (which contains the GyrA E85K change) was used. Reverse transcription-PCR experiments showed that
parE
and
parC
were cotranscribed in R6, T6, and T11; and a single promoter located upstream of
parE
was identified in R6 by primer extension. The fitness of the transformants was estimated by pairwise competition with R6 in both one-cycle and two-cycle experiments. In the one-cycle experiments, most strains carrying the GyrA E85K change showed a fitness cost; the exception was recombinant T14. In the two-cycle experiments, a fitness cost was observed in most first-level transformants carrying the ParC changes S79F, S79Y, and D83Y and the GyrA E85K change; the exceptions were recombinants T6 and T11. The results suggest that there is no impediment due to a fitness cost for the spread of recombinant Cp
r
S. pneumoniae
isolates, since some recombinants (T6, T11, and T14) exhibited an ability to compensate for the cost.
Treatment of Experimental Anthrax with Recombinant Capsule Depolymerase
Authors: Scorpio Angelo , Tobery Steven A. , Ribot Wilson J. , Friedlander Arthur M.
Published: December 2007

Bacillus anthracis
produces an antiphagocytic gamma-linked poly-
d
-glutamic acid capsule that is required for virulence. Capsule depolymerase (CapD) is a membrane-associated poly-γ-glutamate-specific depolymerase encoded on the
B. anthracis
capsule plasmid, pX02, that is reported to contribute to virulence by anchoring the capsule to the peptidoglycan and partially degrading high-molecular-weight capsule from the bacterial surface. We previously demonstrated that treatment with CapD effectively removes the capsule from anthrax bacilli, rendering them susceptible to phagocytic killing in vitro. Here we report that CapD promoted in vivo phagocytic killing of
B. anthracis
bacilli by mouse peritoneal neutrophils and that parenteral administration of CapD protected mice in two models of anthrax infection. CapD conferred significant protection compared with controls when coinjected with encapsulated bacilli from fully virulent
B. anthracis
Ames or the nontoxigenic encapsulated strain ΔAmes and when injected 10 min after infection with encapsulated bacilli from
B. anthracis
Ames. Protection was also observed when CapD was administered 30 h after infection with
B. anthracis
ΔAmes spores, while significant protection could not be demonstrated following challenge with
B. anthracis
Ames spores. These data support the proposed role of capsule in
B. anthracis
virulence and suggest that strategies to target anthrax bacilli for neutrophil killing may lead to novel postexposure therapies.
Fluoroquinolone-Resistant Mutants ofBurkholderia cepacia
Authors: Pope C. F. , Gillespie S. H. , Pratten J. R. , McHugh T. D.
Published: December 2007

Fluoroquinolone-resistantBurkholderia cepaciamutants were selected on ciprofloxacin. The rate of mutation ingyrAwas estimated to be 9.6 × 10−11mutations per division. Mutations ingyrAconferred 12- to 64-fold increases in MIC, and an additionalparCmutation conferred a large increase in MIC (>256-fold). Growth rate, biofilm formation, and survival in water and during drying were not impaired in strains containing singlegyrAmutations. Double mutants were impaired only in growth rate (0.85, relative to the susceptible parent).
Tipranavir (TPV) Genotypic Inhibitory Quotient Predicts Virological Response at 48 Weeks to TPV-Based Salvage Regimens
Authors: de Requena Daniel Gonzalez , Bonora Stefano , Calcagno Andrea , D'Avolio Antonio , Siccardi Marco , Fontana Silvia , Milia Maria Grazia , Sciandra Mauro , Garazzino Silvia , Di Garbo Antonio , Baietto Lorena , Trentini Laura , Di Perri Giovanni
Published: December 2007

The virological response (VR) to a tipranavir-ritonavir (TPV-RTV)-based regimen had been shown to be associated with a number of mutations in the protease gene, the use of enfuvirtide (T20), and the TPV phenotypic inhibitory quotient (IQ). The role of the TPV genotypic IQ (gIQ) has not yet been fully investigated. The aim of our study was to evaluate the relationship between the TPV gIQ and the VR at 48 weeks to TPV-based salvage regimens. Patients placed on regimens containing two nucleoside reverse transcriptase inhibitors plus TPV-RTV 500/200 mg twice a day with or without T20 were prospectively studied. Regular follow-up was performed over the study period. VR, considered a viral load (VL) decrease of ≥1 log unit and/or the achievement of <50 copies/ml with no VL rebound of >0.5 log unit compared to the maximal VL decrease at week 48, was assessed. Thirty-eight patients who had received multiple drugs were included. At week 48 the VL decrease was −1.48 (interquartile range [IQR], −2.88 to −0.48), 15 patients (39.5%) had VLs of <50 copies/ml, and the CD4+cell count increase was 37 cells/mm3(IQR, −30 to +175). Twenty subjects (52.6%) achieved VRs. The TPV gIQ and optimized background score (OBS) were independently associated with higher VL decreases. The TPV gIQ and OBS were also independent predictors of a VR at week 48. TPV gIQ and OBS cutoff values of 14,500 and 2, respectively, were associated with a higher rate of VR. The TPV gIQ was shown to be able to predict the VR at 48 weeks to TPV-containing salvage regimens better than the TPV trough concentration or TPV-associated mutations alone. A possible TPV gIQ cutoff value of 14,500 for reaching a VR at week 48 was suggested. Further studies are needed in order to evaluate the calculation of TPV gIQ as a new tool for the optimization of TPV-based salvage therapy.
Highly Variable Penicillin Resistance Determinants PBP 2x, PBP 2b, and PBP 1a in Isolates of Two
Streptococcus pneumoniae
Clonal Groups, Poland
23F
-16 and Poland
6B
-20
Authors: Izdebski Radosław , Rutschmann Jens , Fiett Janusz , Sadowy Ewa , Gniadkowski Marek , Hryniewicz Waleria , Hakenbeck Regine
Published: December 2007

Penicillin-binding proteins (PBPs) in representatives of two
Streptococcus pneumoniae
clonal groups that are prevalent in Poland, Poland
23F
-16 and Poland
6B
-20, were investigated by PBP profile analysis, antibody reactivity pattern analysis, and DNA sequence analysis of the transpeptidase (TP) domain-encoding regions of the
pbp2x
,
pbp2b
, and
pbp1a
genes. The isolates differed in their MICs of β-lactam antibiotics. The majority of the 6B isolates were intermediately susceptible to penicillin (penicillin MICs, 0.12 to 0.5 μg/ml), whereas all 23F isolates were penicillin resistant (MICs, ≥2 μg/ml). The 6B isolates investigated had the same sequence type (ST), determined by multilocus sequence typing, as the Poland
6B
-20 reference strain (ST315), but in the 23F group, isolates with three distinct single-locus variants (SLVs) in the
ddl
gene (ST173, ST272, and ST1506) were included. None of the isolates showed an identical PBP profile after labeling with Bocillin FL and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and only one pair of 6B isolates and one pair of 23F isolates (ST173 and ST272) each contained an identical combination of PBP 2x, PBP 2b, and PBP 1a TP domains. Some 23F isolates contained PBP 3 with an apparently higher electrophoretic mobility, and this feature also did not correlate with their STs. The data document a highly variable pool of PBP genes as a result of multiple gene transfer and recombination events within and between different clonal groups.
Microbicidal Properties and Cytocidal Selectivity of Rhesus Macaque Theta Defensins
Authors: Tran Dat , Tran Patti , Roberts Kevin , Ösapay George , Schaal Justin , Ouellette Andre , Selsted Michael E.
Published: December 2007

Rhesus macaque θ-defensins (RTDs) are unique macrocyclic antimicrobial peptides. The three RTDs (RTD 1-3), isolated from macaque leukocytes, have broad-spectrum antimicrobial activities in vitro and share certain structural features with acyclic porcine protegrins, which are microbicidal peptides of the cathelicidin family. To understand the structural features that confer the respective cytocidal properties to θ-defensins and protegrins, we determined and compared the biological properties of RTD 1-3 and protegrin 1 (PG-1) in assays for antimicrobial activity, bacterial membrane permeabilization, and toxicity to human cells. RTD 1-3 and PG-1 had similar microbicidal potencies againstEscherichia coli,Staphylococcus aureus, andCandida albicansin low-ionic-strength (10 mM) buffers at pH 7.4. The inclusion of physiologic sodium chloride partially inhibited the microbicidal activities of the RTDs, and the degree of inhibition depended on the buffer used in the assay. Similarly, the inclusion of 10% normal human serum partially antagonized the bactericidal activities of all four peptides. In contrast, the microbicidal activities of PG-1 and RTD 1-3 againstE. coliwere unaffected by physiologic concentrations of calcium chloride and magnesium chloride. Treatment ofE. coliML35 cells with RTD 1-3 or PG-1 rapidly rendered the bacteria permeable toο-nitrophenyl-β-d-galactopyranoside, and this was accompanied by the rapid entry of the RTDs. Finally, although PG-1 was toxic to human fibroblasts and caused a marked lysis of erythrocytes, the RTDs were not cytotoxic or hemolytic. Thus, compared to PG-1, RTD 1-3 possess substantially greater cytocidal selectivity against microbes. Surprisingly, the low cytotoxicity of the RTDs did not depend on the peptides’ cyclic conformation.
The Naphthyridinone GSK364735 Is a Novel, Potent Human Immunodeficiency Virus Type 1 Integrase Inhibitor and Antiretroviral
Authors: Garvey Edward P. , Johns Brian A. , Gartland Margaret J. , Foster Scott A. , Miller Wayne H. , Ferris Robert G. , Hazen Richard J. , Underwood Mark R. , Boros Eric E. , Thompson James B. , Weatherhead Jason G. , Koble Cecilia S. , Allen Scott H. , Schaller Lee T. , Sherrill Ronald G. , Yoshinaga Tomokazu , Kobayashi Masanori , Wakasa-Morimoto Chiaki , Miki Shigeru , Nakahara Koichiro , Noshi Takeshi , Sato Akihiko , Fujiwara Tamio
Published: December 2007

The naphthyridinone GSK364735 potently inhibited recombinant human immunodeficiency virus type 1 (HIV-1) integrase in a strand transfer assay (mean 50% inhibitory concentration ± standard deviation, 8 ± 2 nM). As expected based on the structure of the drug, it bound competitively with another two-metal binding inhibitor (
K

d

[binding constant], 6 ± 4 nM). In a number of different cellular assays, GSK364735 inhibited HIV replication with potency at nanomolar concentrations (e.g., in peripheral blood mononuclear cells and MT-4 cells, 50% effective concentrations were 1.2 ± 0.4 and 5 ± 1 nM, respectively), with selectivity indexes of antiviral activity versus in-assay cytotoxicity of at least 2,200. When human serum was added, the antiviral potency decreased (e.g., a 35-fold decrease in the presence of 100% human serum was calculated by extrapolation from the results of the MT-4 cell assay). In cellular assays, GSK364735 blocked viral DNA integration, with a concomitant increase in two-long-terminal-repeat circles. As expected, this integrase inhibitor was equally active against wild-type viruses and mutant viruses resistant to approved drugs targeting either reverse transcriptase or protease. In contrast, some but not all viruses resistant to other integrase inhibitors were resistant to GSK364735. When virus was passaged in the presence of the inhibitor, we identified resistance mutations within the integrase active site that were the same as or similar to mutations arising in response to other two-metal binding inhibitors. Finally, either additive or synergistic effects were observed when GSK364735 was tested in combination with approved antiretrovirals (i.e., no antagonistic effects were seen). Thus, based on all the data, GSK364735 exerted potent antiviral activity through the inhibition of viral DNA integration by interacting at the two-metal binding site within the catalytic center of HIV integrase.
Urine Bactericidal Activity against
Escherichia coli
Isolates Exhibiting Different Resistance Phenotypes/Genotypes in an In Vitro Pharmacodynamic Model Simulating Urine Concentrations Obtained after Oral Administration of a 400-Milligram Single Dose of Cefditoren-Pivoxil
Authors: Sevillano David , Aguilar Lorenzo , Alou Luis , Giménez María-José , Torrico Martha , González Natalia , Cafini Fabio , Relaño María-Teresa , Coronel Pilar , Prieto José
Published: December 2007

Activity of simulated cefditoren urinary concentrations was determined against seven
Escherichia coli
isolates. Bactericidal activity was obtained from 4 to 24 h against TEM-1 (penicillinase production/hyperproduction), TEM-34 (IRT-6), and TEM-116 (extended-spectrum beta-lactamase [ESBL]) and from 6 to 8 h against SHV/TEM-116 (ESBL) but never against SHV/TEM-1 (ESBL). Extension of bactericidal activity depended on the resistance genotype/phenotype tested.
Enhanced Production of Phospholipase C and Perfringolysin O (Alpha and Theta Toxins) in a Gatifloxacin-Resistant Strain of
Clostridium perfringens
Authors: Rafii Fatemeh , Park Miseon , Bryant Amy E. , Johnson Shemedia J. , Wagner Robert D.
Published: December 2007

Clostridium perfringens
-induced gas gangrene is mediated by potent extracellular toxins, especially alpha toxin (a phospholipase C [PLC]) and theta toxin (perfringolysin O [PFO], a thiol-activated cytolysin); and antibiotic-induced suppression of toxin synthesis is an important clinical goal. The production of PLC and PFO by a gatifloxacin-induced, fluoroquinolone-resistant mutant strain of
C. perfringens
, strain 10G, carrying a stable mutation in DNA gyrase was compared with that of the wild-type (WT) parent strain. Zymography (with sheep red blood cell and egg yolk overlays) and time course analysis [with hydrolysis of egg yolk lecithin and
O
-(4 nitrophenyl-phosphoryl)choline] demonstrated that strain 10G produced more PLC and PFO than the WT strain. Increased toxin production in strain 10G was not related either to differences in growth characteristics between the wild-type and the mutant strain or to nonsynonymous polymorphisms in PLC, PFO, or their known regulatory proteins. Increased PLC and PFO production by strain 10G was associated with increased cytotoxic activity for HT-29 human adenocarcinoma cells and with increased platelet-neutrophil aggregate formation. Four other gatifloxacin-induced gyrase mutants did not show increased toxin production, suggesting that gatifloxacin resistance was not always associated with increased toxin production in all strains of
C. perfringens
. This is the first report of increased toxin production in a fluoroquinolone-resistant strain of
C. perfringens
.
Assessment of Serum (1→3)-β-
d
-Glucan Concentration as a Measure of Disease Burden in a Murine Model of Invasive Pulmonary Aspergillosis
Authors: Wiederhold Nathan P. , Najvar Laura K. , Vallor Ana C. , Kirkpatrick William R. , Bocanegra Rosie , Molina Destiny , Olivo Marcos , Graybill John R. , Patterson Thomas F.
Published: December 2007

Serum (1→3)-β-
d
-glucan concentrations were serially measured in the presence and absence of antifungal therapy in a murine model of invasive pulmonary aspergillosis. Serum (1→3)-β-
d
-glucan was detected early during the course of infection, and reductions in this biomarker were associated with improved survival in animals treated with antifungal agents.
Monoclonal Antibodies That Bind to Common Epitopes on the Dengue Virus Type 2 Nonstructural-1 and Envelope Glycoproteins Display Weak Neutralizing Activity and Differentiated Responses to Virulent Strains: Implications for Pathogenesis and Vaccines
Authors: Falconar Andrew K. I.
Published: December 2007

The abilities of monoclonal antibodies (MAbs) that bind to defined sequential epitopes on the dengue virus (DENV) nonstructural-1 (NS1) glycoproteins to cross-react with epitopes on the DENV envelope (E) glycoproteins were investigated. In this study, some of these MAbs cross-reacted with the DENV type 2 (DENV-2) E glycoprotein and with synthetic peptides representing X-ray crystallographically confirmed surface-exposed regions on this glycoprotein. MAb 1G5.3 cross-reacted with the flavivirus-conserved 101-WGNGCGLFG-109 fusion sequence, the 273-SSGNL-277 DENV-2 hinge region sequence, and the 156-GKHGKEIKIT-165 sequence of virulent DENV-2 strains. MAb 1G5.4-A1-C3 cross-reacted with the 67-NTTTESRCPT-76 and 156-GKHGKEIKIT-165 sequences of virulent DENV-2 strains, the 338-EIMDLDNRHV-347 sequence from a highly virulent DENV-2 (M2) strain, and two epitopes on a virulent DENV-3 strain (288-KMDKLELKG-296 and 323-RVEYRGEDAP-332), which all contained target ELK/KLE-type motifs (underlined). These MAbs showed reduced cross-reactions with the corresponding sequences from weakly pathogenic strains of all four DENV serotypes and had either no (MAb 1G5.4-A1-C3) or weak (MAb 1G5.3) neutralizing activity against them. MAb 1G5.3 more strongly neutralized DENV-2 strains with higher pathogenic capacities, while MAb 1G5.4-A1-C3 showed increasing neutralizing titers against the virulent DENV-3 strain and the moderately virulent and highly virulent (M2) DENV-2 strains. These cross-reactions with the E glycoprotein accord with the observation that MAb 1G5.3 caused dramatic and lethal antibody-enhanced replication (AER) of a DENV-2 strain in vivo. Together with in vivo AER studies of these DENV strains using MAb 1G5.4-A1-C3, these results may account for the increased pathogenic capacities of such strains, which is likely to have important implications for pathogenesis and vaccines.
Reduction of Chemokine Secretion in Response to Mycobacteria in Infliximab-Treated Patients
Authors: Newton Sandra M. , Mackie Sarah L. , Martineau Adrian R. , Wilkinson Katalin A. , Kampmann Beate , Fisher Corinne , Dutta Shouma , Levin Michael , Wilkinson Robert J. , Pasvol Geoffrey
Published: December 2007

The use of anti-tumor necrosis factor (TNF) agents as a treatment for chronic inflammatory conditions has been shown to be associated with an increased risk of developing tuberculosis. We studied the effect of the anti-TNF antibody infliximab on antimycobacterial immunity in 26 patients with rheumatoid arthritis or ankylosing spondylitis by use of an in vitro whole-blood model employing a reporter mycobacterium. Blood samples taken before and 30 min and 7 days after a 2-hour infliximab infusion were compared in terms of their abilities both to suppress luminescence ofMycobacterium bovisbacillus Calmette-Guérinluxand to secrete chemokines and cytokines 24 and 96 h after infection. No immediate effect of infliximab on mycobacterial luminescence was detected using this bioassay, irrespective of whether patients were receiving their first (n= 14) or maintenance (n= 12) doses of infliximab. Moreover, no effect on mycobacterial luminescence was detected when blood was taken 7 days after infliximab treatment (n= 7). By contrast, there was a significant reduction in the chemokines implicated in cellular trafficking, namely, interleukin-8, macrophage-inhibitory protein-1α (MIP-1α), MIP-1β (24 h and 96 h), and monocyte chemoattractant protein-1 (MCP-1) (24 h) following BCGluxstrain infection in the 30-minute post-infliximab-infusion blood samples (P< 0.05). This effect was sustained by MIP-1β and MCP-1 (24 h;P< 0.05) at 7 days after infusion. Our results suggest that the development of tuberculosis in infliximab-treated patients is not directly related to the mycobactericidal effects of TNF but may be due to inhibition of TNF-dependent chemokine gradients disrupting cellular migration necessary to maintain the integrity of the granuloma.
Borrelia burgdorferiComplement Regulator-Acquiring Surface Protein 2 (CspZ) as a Serological Marker of Human Lyme Disease
Authors: Kraiczy Peter , Seling Annekatrin , Brissette Catherine A. , Rossmann Evelyn , Hunfeld Klaus-Peter , Bykowski Tomasz , Burns Logan H. , Troese Matthew J. , Cooley Anne E. , Miller Jennifer C. , Brade Volker , Wallich Reinhard , Casjens Sherwood , Stevenson Brian
Published: December 2007

Serological diagnosis of Lyme disease may be complicated by antigenic differences between infecting organisms and those used as test references. Accordingly, it would be helpful to include antigens whose sequences are well conserved by a broad range of Lyme disease spirochetes. In the present study, line blot analyses were performed using recombinant complement regulator-acquiring surface protein 2 (BbCRASP-2) fromBorrelia burgdorferisensu stricto strain B31 and serum samples from human Lyme disease patients from throughout the United States and Germany. The results indicated that a large proportion of the patients had produced antibodies recognizing recombinant BbCRASP-2. In addition, Lyme disease spirochetes isolated from across North America and Europe were found to contain genes encoding proteins with high degrees of similarity to theB. burgdorferitype strain B31 BbCRASP-2, consistent with the high percentage of serologically positive patients. These data indicate that BbCRASP-2 may be valuable for use in a widely effective serological assay.
Evaluation of the Antigenic Relationships among Canine Parvovirus Type 2 Variants
Authors: Cavalli Alessandra , Martella Vito , Desario Costantina , Camero Michele , Bellacicco Anna Lucia , De Palo Pasquale , Decaro Nicola , Elia Gabriella , Buonavoglia Canio
Published: December 2007

The antigenic relationships among the original canine parvovirus type 2 (CPV-2) and the variants CPV-2a, -2b, and -2c were evaluated. Cross-antigenic evaluation revealed clear differences among the CPV variants, which were more appreciable by serum neutralization (SN) than by hemagglutination inhibition. Antigenic differences were found mostly between the original CPV-2 and the variants, but they were also observed among the variants CPV-2a, -2b, and -2c. The variant CPV-2c exhibited a unique antigenic pattern, since it was poorly recognized by the sera of animals immunized with CPV-2, CPV-2a, and CPV-2b. However, animals immunized with CPV-2c exhibited higher SN titers to CPV-2b than to the homologous virus CPV-2c. The observed antigenic differences might drive selection of CPV strains by generating differential immune pressure in the canine population, which raises concerns about vaccine efficacy.
Class II-Restricted Protective Immunity Induced by Malaria Sporozoites
Authors: Oliveira Giane A. , Kumar Kota Arun , Calvo-Calle J. Mauricio , Othoro Caroline , Altszuler David , Nussenzweig Victor , Nardin Elizabeth H.
Published: December 2007

The irradiated-sporozoite vaccine elicits sterile immunity againstPlasmodiumparasites in experimental rodent hosts and human volunteers. Based on rodent malaria models, it has been proposed that CD8+T cells are the key protective effector mechanism required in sporozoite-induced immunity. To investigate the role of class II-restricted immunity in protective immunity, we immunized β2-microglobulin knockout (β2M−/−) mice with irradiatedPlasmodium yoeliiorP. bergheisporozoites. Sterile immunity was obtained in the CD8+-T-cell-deficient mice immunized with eitherP. bergheiorP. yoeliisporozoites. β2M−/−mice with the BALB/c (H-2d) genetic background as well as those with the C57BL (H-2b) genetic background were protected. Effector mechanisms included CD4+T cells, mediated in part through the production of gamma interferon, and neutralizing antibodies that targeted the extracellular sporozoites. We conclude that in the absence of class I-restricted CD8+T cells, sporozoite-induced protective immunity can be effectively mediated by class II-restricted immune effector mechanisms. These results support efforts to develop subunit vaccines that effectively elicit high levels of antibody and CD4+T cells to targetPlasmodiumpreerythrocytic stages.
Peritoneal Challenge Modulates Expression of Pneumococcal Surface Protein C during Bacteremia in Mice
Authors: Quin Lisa R. , Moore Quincy C. , Thornton Justin A. , McDaniel Larry S.
Published: December 2007

Differential expression of pneumococcal virulence proteins has been demonstrated. We previously demonstrated challenge route-dependent differences in pneumococcal surface protein C (PspC) expression during bacteremia. In this study, we investigated differences in PspC expression during the transition of pneumococci from the peritoneum to the blood. Time course analysis of PspC expression using flow cytometry demonstrated that
Streptococcus pneumoniae
D39 collected from blood expressed significantly more PspC than did D39 collected from the peritoneum of intraperitoneally (i.p.)-infected mice. Various challenge models were then used to determine whether host responses originating from the peritoneum can influence PspC expressed by pneumococci in the blood. Using heat-inactivated D39 (HI-D39) and sterile peritoneal dialysis fluid (PDF), we investigated whether stimulation of peritoneal responses can influence PspC expression. Injection of mice i.p. with HI-D39 or PDF immediately prior to intravenous (i.v.) infection with D39 caused a significant increase in PspC expressed by D39 in the blood. Finally, we used cytokine array analysis to investigate specific inflammatory mediators that may result in differential PspC expression. Of the 96 inflammatory cytokines assayed, D39 i.p. challenge led to increased expression of 33 cytokines in serum; whereas D39 i.v. challenge led to increased expression of 15 and decreased expression of 11 cytokines relative to serum of the uninfected control. These results indicate that PspC is differentially regulated during growth in vivo and that the level of expression varies depending on the host environment.
The Proteasome Immunosubunit Multicatalytic Endopeptidase Complex-Like 1 Is a T-Cell-Intrinsic Factor Influencing Homeostatic Expansion
Authors: Zaiss Dietmar M. W. , de Graaf Natascha , Sijts Alice J. A. M.
Published: December 2007

Homeostatic regulatory mechanisms maintain the constant ratios between different lymphocyte subsets in the secondary lymphoid organs. How this dynamic equilibrium is achieved, in particular following the clonal expansion and subsequent contraction of different cells after infection, remains poorly understood. Expression of the proteasome immunosubunits has been shown to influence not only major histocompatibility complex class I (MHC-I) antigen processing and thereby T-cell responses, but also the CD4/CD8 T-cell ratios in lymphoid organs. We examined the relationships between these different immunosubunit-mediated effects in mice of various proteasome subunit compositions during infection with
Listeria monocytogenes
. Mice that lacked the immunosubunit multicatalytic endopeptidase complex-like 1 (MECL-1) maintained enhanced CD4/CD8 T-cell ratios during infection, while MHC-I surface levels resembled those in wild-type (wt) mice. LMP7 gene-deficient mice, on the other hand, showed reduced MHC-I expression, while their splenic CD4/CD8 ratios were similar to those in wt mice. Remarkably, analysis of bone marrow-chimeric immunosubunit gene-deficient mice, reconstituted with a mixture of wt and LMP7- plus MECL-1-deficient bone marrow, revealed that the LMP7- plus MECL-1-deficient T-cell population maintained a higher CD4/CD8 T-cell ratio than the wt T-cell population before, during, and after infection and T-cell memory formation. Since in these mice the immunosubunit-positive and immunosubunit-negative T-cell populations were selected in the same thymus and expanded in the same lymphoid environments, our findings indicate that MECL-1 influences the homeostatic equilibrium between T-cell subsets, not through indirect extracellular signals, such as MHC-I expression or the cytokine milieu, but through direct effects on T-cell-intrinsic processes.
Expression of Cathelicidin LL-37 duringMycobacterium tuberculosisInfection in Human Alveolar Macrophages, Monocytes, Neutrophils, and Epithelial Cells
Authors: Rivas-Santiago Bruno , Hernandez-Pando Rogelio , Carranza Claudia , Juarez Esmeralda , Contreras Juan Leon , Aguilar-Leon Diana , Torres Martha , Sada Eduardo
Published: December 2007

The innate immune response in human tuberculosis is not completely understood. To improve our knowledge regarding the role of cathelicidin hCAP-18/LL37 in the innate immune response to tuberculosis infection, we used immunohistochemistry, immunoelectron microscopy, and gene expression to study the induction and production of the antimicrobial peptide in A549 epithelial cells, alveolar macrophages (AM), neutrophils, and monocyte-derived macrophages (MDM) after infection withMycobacterium tuberculosis. We demonstrated that mycobacterial infection induced the expression and production of LL-37 in all cells studied, with AM being the most efficient. We did not detect peptide expression in tuberculous granulomas, suggesting that LL-37 participates only during early infection. Through the study of Toll-like receptors (TLR) in MDM, we showed that LL-37 can be induced by stimulation through TLR-2, TLR-4, and TLR-9. This last TLR was strongly stimulated byM. tuberculosisDNA. We concluded that LL-37 may have an important role in the innate immune response againstM. tuberculosis.
Coordinate Regulation of
Salmonella
Pathogenicity Island 1 (SPI1) and SPI4 in
Salmonella enterica
Serovar Typhimurium
Authors: Main-Hester Kara L. , Colpitts Katherine M. , Thomas Gracie A. , Fang Ferric C. , Libby Stephen J.
Published: December 2007

Salmonella enterica
serovar Typhimurium harbors five pathogenicity islands (SPI) required for infection in vertebrate hosts. Although the role of SPI1 in promoting epithelial invasion and proinflammatory cell death has been amply documented, SPI4 has only more recently been implicated in
Salmonella
virulence. SPI4 is a 24-kb pathogenicity island containing six open reading frames,
siiA
to
siiF
. Secretion of the 595-kDa SiiE protein requires a type I secretory system encoded by
siiC
,
siiD
, and
siiF
. An operon polarity suppressor (
ops
) sequence within the 5′ untranslated region upstream of
siiA
is required for optimal SPI4 expression and predicted to bind the antiterminator RfaH. SiiE concentrations are decreased in a SPI1 mutant strain, suggesting that SPI1 and SPI4 may have common regulatory inputs. SPI1 gene expression is positively regulated by the transcriptional activators HilA, HilC, and HilD, encoded within SPI1, and negatively regulated by the regulators HilE and PhoP. Here, we show that mutations in
hilA
,
hilC
, or
hilD
similarly reduce expression of
siiE
, and mutations in
hilE
or
phoP
enhance
siiE
expression. Individual overexpression of HilA, HilC, or HilD in the absence of SPI1 cannot activate
siiE
expression, suggesting that these transcriptional regulators act in concert or in combination with additional SPI1-encoded regulatory loci to activate SPI4. HilA is no longer required for
siiE
expression in an
hns
mutant strain, suggesting that HilA promotes SPI4 expression by antagonizing the global transcriptional silencer H-NS. Coordinate regulation suggests that SPI1 and SPI4 play complementary roles in the interaction of
S. enterica
serovar Typhimurium with the host intestinal mucosa.
The Hek Outer Membrane Protein of
Escherichia coli
Strain RS218 Binds to Proteoglycan and Utilizes a Single Extracellular Loop for Adherence, Invasion, and Autoaggregation
Authors: Fagan Robert P. , Lambert Matthew A. , Smith Stephen G. J.
Published: December 2007

Escherichia coli
is the principal gram-negative causative agent of sepsis and meningitis in neonates. The pathogenesis of meningitis due to
E. coli
K1 involves mucosal colonization, transcytosis of epithelial cells, survival in the bloodstream, and eventually invasion of the meninges. The last two aspects have been well characterized at a molecular level. Less is known about the early stages of pathogenesis, i.e., adhesion to and invasion of epithelial cells. We have previously reported that the Hek protein causes autoaggregation and can mediate adherence to and invasion of epithelial cells. Here, we report that Hek-mediated adherence is dependent on binding to glycosoaminoglycan, in particular, heparin. The ability to hemagglutinate, autoaggregate, adhere, and invade is contingent on a putative 25-amino-acid loop that is exposed to the outside of the bacterial cells.
C-Terminal Repeats ofClostridium difficileToxin A Induce Production of Chemokine and Adhesion Molecules in Endothelial Cells and Promote Migration of Leukocytes
Authors: Yeh Chiou-Yueh , Lin Chun-Nan , Chang Chuan-Fa , Lin Chun-Hung , Lien Huei-Ting , Chen Jen-Yang , Chia Jean-San
Published: December 2007

The C-terminal repeating sequences ofClostridium difficiletoxin A (designated ARU) are homologous to the carbohydrate-binding domain of streptococcal glucosyltransferases (GTFs) that were recently identified as potent modulins. To test the hypothesis that ARU might exert a similar biological activity on endothelial cells, recombinant ARU (rARU), which was noncytotoxic to cell cultures, was analyzed using human umbilical vein endothelial cells. The rARU could bind directly to endothelial cells in a serum- and calcium-dependent manner and induce the production of interleukin-6 (IL-6), IL-8, and monocyte chemoattractant protein 1 in a dose-dependent manner. An oligosaccharide binding assay indicated that rARU, but not GTFC, binds preferentially to Lewis antigens and 3′HSO3-containing oligosaccharides. Binding of rARU to human endothelial or intestinal cells correlated directly with the expression of Lewis Y antigen. Bound rARU directly activated mitogen-activated protein kinases and the NF-κB signaling pathway in endothelial cells to release biologically active chemokines and adhesion molecules that promoted migration in a transwell assay and the adherence of polymorphonuclear and mononuclear cells to the endothelial cells. These results suggest that ARU may bind to multiple carbohydrate motifs to exert its biological activity on human endothelial cells.
Differential Uptake and Processing of a
Haemophilus influenzae
P5-Derived Immunogen by Chinchilla Dendritic Cells
Authors: Novotny Laura A. , Partida-Sánchez Santiago , Munson Robert S. , Bakaletz Lauren O.
Published: December 2007

Dendritic cells (DCs) are potent antigen-presenting cells involved in the initiation and modulation of immune responses after immunization via their ability to process and present antigen to naive T cells. We wanted to examine the role of DCs in the development of protective immunity against nontypeable
Haemophilus influenzae
(NTHI)-induced experimental otitis media (OM) after intranasal immunization of chinchillas with an NTHI P5-derived synthetic peptide immunogen called LB1. As chinchilla DCs have not been described, we adapted well-established protocols to induce the differentiation of chinchilla bone marrow precursor cells into DCs, which resulted in cells that were morphologically and phenotypically similar to DCs of other species. In vitro, chinchilla DCs readily internalized LB1, upregulated expression of the maturation markers CD80 and major histocompatibility complex class II, and presented processed LB1 to primed CD3
+
T cells, which resulted in antigen-specific T-cell proliferation. In vivo, LB1-activated DCs trafficked from the chinchilla nasal cavity primarily to the nasal-associated lymphoid tissues and were detected in close proximity to CD3
+
T cells within this lymphoid aggregate. These data are the first to characterize chinchilla DCs and their functional properties. Furthermore, they suggest an important role for chinchilla DCs in the development of protective immunity against experimental NTHI-induced OM after intranasal immunization.
Enteric Salmonellosis Disrupts the Microbial Ecology of the Murine Gastrointestinal Tract
Authors: Barman Melissa , Unold David , Shifley Kathleen , Amir Elad , Hung Kueichun , Bos Nicolaas , Salzman Nita
Published: December 2007

The commensal microbiota protects the murine host from enteric pathogens. Nevertheless, specific pathogens are able to colonize the intestinal tract and invade, despite the presence of an intact biota. Possibly, effective pathogens disrupt the indigenous microbiota, either directly through pathogen-commensal interaction, indirectly via the host mucosal immune response to the pathogen, or by a combination of these factors. This study investigates the effect of peroral
Salmonella enterica
serovar Typhimurium infection on the intestinal microbiota. Since the majority of the intestinal microbiota cannot be cultured by conventional techniques, molecular approaches using 16S rRNA sequences were applied. Several major bacterial groups were assayed using quantitative PCR. Administration of either the 50% lethal dose (LD
50
) or 10× LD
50
of
Salmonella enterica
serovar Typhimurium caused changes in the microbiota throughout the intestinal tract over the time course of infection. A 95% decrease in total bacterial number was noted in the cecum and large intestine with 10× LD
50
S. enterica
serovar Typhimurium challenge at 7 days postinfection, concurrent with gross evidence of diarrhea. In addition, alterations in microbiota composition preceded the onset of diarrhea, suggesting the involvement of pathogen-commensal interactions and/or host responses unrelated to diarrhea. Microbiota alterations were not permanent and reverted to the microbiota of uninfected mice by 1 month postinfection. Infection with a
Salmonella
pathogenicity island 1 (SPI1) mutant did not result in microbiota alterations, while SPI2 mutant infections triggered partial changes. Neither mutant was capable of prolonged colonization or induction of mucosal inflammation. These data suggest that several
Salmonella
virulence factors, particularly those involved in the local mucosal host response, are required for disruption of the intestinal ecosystem.