bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genetic Context and Biochemical Characterization of the IMP-18 Metallo-β-Lactamase Identified in a
Pseudomonas aeruginosa
Isolate from the United States
Authors: Borgianni Luisa , Prandi Silvia , Salden Laurie , Santella Gisela , Hanson Nancy D. , Rossolini Gian Maria , Docquier Jean-Denis 
Published: November 2010

ABSTRACT

The production of metallo-β-lactamase (MBL) is an important mechanism of resistance to β-lactam antibiotics, including carbapenems. Despite the discovery and emergence of many acquired metallo-β-lactamases, IMP-type determinants (now counting at least 27 variants) remain the most prevalent in some geographical areas. In Asian countries, and notably Japan, IMP-1 and its closely related variants are most widespread. Some other variants have been detected in other countries and show either an endemic (e.g., IMP-13 in Italy) or sporadic (e.g., IMP-12 in Italy or IMP-18 in the United States) occurrence. The IMP-18-producing
Pseudomonas aeruginosa
strain PS 297 from the southwestern United States carried at least two class 1 integrons. One was identical to In
51
, while the other, named In
133
and carrying the
bla
IMP-18
gene cassette in the third position, showed an original array of five gene cassettes, including
aacA7
,
qacF
,
aadA1
, and an unknown open reading frame (ORF). Interestingly. In
133
differed significantly from In
96
, the
bla
IMP-18
-carrying integron identified in a
P. aeruginosa
isolate from Mexico. The meropenem and ertapenem MIC values were much lower for
Escherichia coli
strains producing IMP-18 (0.06 and 0.12 μg/ml, respectively) than for strains producing IMP-1 (2 μg/ml for each). Kinetic data obtained with the purified enzyme revealed lower turnover rates of IMP-18 than of other IMP-type enzymes with most substrates.
Polymyxin-Resistant Clinical Isolates of
Escherichia
coli
Authors: Urban Carl , Tiruvury Hemavarna , Mariano Noriel , Colon-Urban Rita , Rahal James J. 
Published: November 2010

ABSTRACT

A surveillance study to identify patients from the community with
Escherichia
coli
resistant to broad-spectrum cephalosporins discovered two isolates that were also resistant to polymyxin B and colistin. One isolate from a patient in the community and a second from a patient who received multiple courses of polymyxin B also possessed a CTX-M-15 enzyme. Resistance to cationic peptides in
E
.
coli
is unusual, and testing for susceptibility to these agents should be performed.
Simultaneous Presence of PrtH and PrtH2 Proteinases in
Lactobacillus helveticus
Strains Improves Breakdown of the Pure α
s1
-Casein
Authors: Sadat-Mekmene L. , Jardin J. , Corre C. , Mollé D. , Richoux R. , Delage M.-M. , Lortal S. , Gagnaire V. 
Published: October 2010

ABSTRACT

Lactobacillus helveticus
can possess one or two cell envelope proteinases (CEPs), called PrtH2 and PrtH. The aim of this work was to explore the diversity of 15 strains of
L. helveticus
, isolated from various origins, in terms of their proteolytic activities and specificities on pure caseins or on milk casein micelles. CEP activity differed 14-fold when the strains were assayed on a synthetic substrate, but no significant differences were detected between strains possessing one or two CEPs. No correlation was observed between the proteolytic activities of the strains and their rates of acidification in milk. The kinetics of hydrolysis of purified α
s1
- and β-casein by
L. helveticus
whole cells was monitored using Tris-Tricine sodium dodecyl sulfate (SDS) electrophoresis, and for four strains, the peptides released were identified using mass spectrometry. While rapid hydrolysis of pure β-casein was observed for all strains, the hydrolysis kinetics of α
s1
-casein was the only criterion capable of distinguishing between the strains based on the number of CEPs. Fifty-four to 74 peptides were identified for each strain. When only PrtH2 was present, 22 to 30% of the peptides originated from α
s1
-casein. The percentage increased to 41 to 49% for strains in which both CEPs were expressed. The peptide size ranged from 6 to 33 amino acids, revealing a broad range of cleavage specificities, involving all classes of amino acids (Leu, Val, Ala, Ile, Glu, Gln, Lys, Arg, Met, and Pro). Regions resistant to proteolysis were identified in both caseins. When strains were grown in milk, a drastic reduction in the number of peptides was observed, reflecting changes in accessibility and/or peptide assimilation during growth.
Development of an Efficient Real-Time Quantitative PCR Protocol for Detection ofXanthomonas arboricolapv. pruni inPrunusSpecies
Authors: Palacio-Bielsa Ana , Cubero Jaime , Cambra Miguel A. , Collados Raquel , Berruete Isabel M. , López María M. 
Published: October 2010

ABSTRACTXanthomonas arboricolapv. pruni, the causal agent of bacterial spot disease of stone fruit, is considered a quarantine organism by the European Union and the European and Mediterranean Plant Protection Organization (EPPO). The bacterium can undergo an epiphytic phase and/or be latent and can be transmitted by plant material, but currently, only visual inspections are used to certify plants as beingX. arboricolapv. pruni free. A novel and highly sensitive real-time TaqMan PCR detection protocol was designed based on a sequence of a gene for a putative protein related to an ABC transporter ATP-binding system inX. arboricolapv. pruni. Pathogen detection can be completed within a few hours with a sensitivity of 102CFU ml−1, thus surpassing the sensitivity of the existing conventional PCR. Specificity was assessed forX. arboricolapv. pruni strains from different origins as well as for closely relatedXanthomonasspecies, non-Xanthomonasspecies, saprophytic bacteria, and healthyPrunussamples. The efficiency of the developed protocol was evaluated with field samples of 14Prunusspecies and rootstocks. For symptomatic leaf samples, the protocol was very efficient even when washed tissues of the leaves were directly amplified without any previous DNA extraction. For samples of 117 asymptomatic leaves and 285 buds, the protocol was more efficient after a simple DNA extraction, andX. arboricolapv. pruni was detected in 9.4% and 9.1% of the 402 samples analyzed, respectively, demonstrating its frequent epiphytic or endophytic phase. This newly developed real-time PCR protocol can be used as a quantitative assay, offers a reliable and sensitive test forX. arboricolapv. pruni, and is suitable as a screening test for symptomatic as well as asymptomatic plant material.
Cadherin, Alkaline Phosphatase, and Aminopeptidase N as Receptors of Cry11Ba Toxin from
Bacillus thuringiensis
subsp.
jegathesan
in
Aedes aegypti
Authors: Likitvivatanavong Supaporn , Chen Jianwu , Bravo Alejandra , Soberón Mario , Gill Sarjeet S. 
Published: October 2010

ABSTRACT

Cry11Ba is one of the most toxic proteins to mosquito larvae produced by
Bacillus thuringiensis
. It binds
Aedes aegypti
brush border membrane vesicles (BBMV) with high affinity, showing an apparent dissociation constant (

K
d

) of 8.2 nM. We previously reported that an anticadherin antibody competes with Cry11Ba binding to BBMV, suggesting a possible role of cadherin as a toxin receptor. Here we provide evidence of specific cadherin repeat regions involved in this interaction. Using cadherin fragments as competitors, a C-terminal fragment which contains cadherin repeat 7 (CR7) to CR11 competed with Cry11Ba binding to BBMV. This binding was also efficiently competed by the CR9, CR10, and CR11 peptide fragments. Moreover, we show CR11 to be an important region of interaction with Cry11Ba toxin. An alkaline phosphatase (AaeALP1) and an aminopeptidase-N (AaeAPN1) also competed with Cry11Ba binding to
Ae. aegypti
BBMV. Finally, we found that Cry11Ba and Cry4Ba share binding sites. Synthetic peptides corresponding to loops α8, β2-β3 (loop 1), β8-β9, and β10-β11 (loop 3) of Cry4Ba compete with Cry11Ba binding to BBMV, suggesting Cry11Ba and Cry4Ba have common sites involved in binding
Ae. aegypti
BBMV. The data suggest that three different
Ae. aegypti
midgut proteins, i.e., cadherin, AaeALP1, and AaeAPN1, are involved in Cry11Ba binding to
Ae. aegypti
midgut brush border membranes.
Detection of Clonal Group A
Escherichia coli
Isolates from Broiler Chickens, Broiler Chicken Meat, Community-Dwelling Humans, and Urinary Tract Infection (UTI) Patients and Their Virulence in a Mouse UTI Model
Authors: Jakobsen Lotte , Hammerum Anette M. , Frimodt-Møller Niels 
Published: October 2010

ABSTRACT

Escherichia coli
clonal group A isolates cause infections in people. We investigated 158 phylogroup D
E. coli
isolates from animals, meat, and humans. Twenty-five of these isolates were of clonal group A, and 15 isolates were shown to cause infection in a mouse urinary tract infection (UTI) model. We conclude that clonal group A isolates are found in both broiler chickens and broiler chicken meat and may cause UTI in humans.
Structural Dissection and
In Vivo
Effectiveness of a Peptide Inhibitor of
Porphyromonas gingivalis
Adherence to
Streptococcus gordonii
Authors: Daep Carlo Amorin , Novak Elizabeth A. , Lamont Richard J. , Demuth Donald R. 
Published: November 2010

ABSTRACT

The interaction of the minor fimbrial antigen (Mfa) with streptococcal antigen I/II (e.g., SspB) facilitates colonization of the dental biofilm by
Porphyromonas gingivalis.
We previously showed that a 27-mer peptide derived from SspB (designated BAR) resembles the nuclear receptor (NR) box protein-protein interacting domain and potently inhibits this interaction
in vitro
. Here, we show that the EXXP motif upstream of the NR core α-helix contributes to the Mfa-SspB interaction and that BAR reduces
P. gingivalis
colonization and alveolar bone loss
in vivo
in a murine model of periodontitis. Substitution of Gln for Pro
1171
or Glu
1168
increased the α-helicity of BAR and reduced its inhibitory activity
in vitro
by 10-fold and 2-fold, respectively. To determine if BAR prevents
P. gingivalis
infection
in vivo
, mice were first infected with
Streptococcus gordonii
and then challenged with
P. gingivalis
in the absence and presence of BAR. Animals that were infected with either 10
9
CFU of
S. gordonii
DL-1 or 10
7
CFU of
P. gingivalis
33277 did not show a statistically significant increase in alveolar bone resorption over sham-infected controls. However, infection with 10
9
CFU of
S. gordonii
followed by 10
7
CFU of
P. gingivalis
induced significantly greater bone loss (
P
< 0.01) than sham infection or infection of mice with either organism alone.
S. gordonii
-infected mice that were subsequently challenged with 10
7
CFU of
P. gingivalis
in the presence of BAR exhibited levels of bone resorption similar to those of sham-infected animals. Together, these results indicate that both EXXP and the NR box are important for the Mfa-SspB interaction and that BAR peptide represents a potential therapeutic that may limit colonization of the oral cavity by
P. gingivalis
.
Modifications to the Peptidoglycan Backbone Help Bacteria To Establish Infection
Authors: Davis Kimberly M. , Weiser Jeffrey N. 
Published: November 2010

ABSTRACT
Bacterial pathogens that colonize mucosal surfaces have acquired resistance to antimicrobials that are abundant at these sites. One of the main antimicrobials present on mucosal surfaces is lysozyme, a muramidase that hydrolyzes the peptidoglycan backbone of bacteria. Cleavage of the peptidoglycan backbone leads to bacterial cell death and lysis, which releases bacterial fragments, including peptidoglycan, at the site of infection. Peptidoglycan fragments can be recognized by host receptors and initiate an immune response that will aid in clearing infection. Many mucosal pathogens modify the peptidoglycan residues surrounding the cleavage site for lysozyme to avoid peptidoglycan degradation and the release of these proinflammatory fragments. This review will focus specifically on peptidoglycan modifications, their role in lysozyme resistance, and downstream effects on the host immune response to infection.
A
fadD
mutant of
Vibrio cholerae
Is Impaired in the Production of Virulence Factors and Membrane Localization of the Virulence Regulatory Protein TcpP
Authors: Ray Sreejana , Chatterjee Epshita , Chatterjee Arpita , Paul Kalidas , Chowdhury Rukhsana 
Published: November 2010

ABSTRACT

In the enteric pathogen
Vibrio cholerae
, expression of the major virulence factors is controlled by the hierarchical expression of several regulatory proteins comprising the ToxR regulon. In this study, we demonstrate that disruption of the
fadD
gene encoding a long-chain fatty acyl coenzyme A ligase has marked effects on expression of the ToxR virulence regulon, motility, and
in vivo
lethality of
V. cholerae
. In the
V. cholerae fadD
mutant, expression of the major virulence genes
ctxAB
and
tcpA
, encoding cholera toxin (CT), and the major subunit of the toxin-coregulated pilus (TCP) was drastically repressed and a growth-phase-dependent reduction in the expression of
toxT
, encoding the transcriptional activator of
ctxAB
and
tcpA
, was observed. Expression of
toxT
from an inducible promoter completely restored CT to wild-type levels in the
V. cholerae fadD
mutant, suggesting that FadD probably acts upstream of
toxT
expression. Expression of
toxT
is activated by the synergistic effect of two transcriptional regulators, TcpP and ToxR. Reverse transcription-PCR and Western blot analysis indicated that although gene expression and production of both TcpP and ToxR are unaffected in the
fadD
mutant strain, membrane localization of TcpP, but not ToxR, is severely impaired in the
fadD
mutant strain from the mid-logarithmic phase of growth. Since the decrease in
toxT
expression occurred concomitantly with the reduction in membrane localization of TcpP, a direct correlation between the defect in membrane localization of TcpP and reduced
toxT
expression in the
fadD
mutant strain is suggested.
Strain-Specific Polymorphisms in Paneth Cell α-Defensins of C57BL/6 Mice and Evidence of Vestigial Myeloid α-Defensin Pseudogenes
Authors: Shanahan Michael T. , Tanabe Hiroki , Ouellette André J. 
Published: November 2010

ABSTRACTPaneth cells at the base of small intestinal crypts secrete microbicidal α-defensins, termed cryptdins (Crps) in mice, as mediators of innate immunity. Proteomic studies show that five abundant Paneth cell α-defensins in C57BL/6 mice are strain specific in that they have not been identified in other inbred strains of mice. Two C57BL/6-specific peptides are coded for by theDefcr20and -21genes evident in the NIH C57BL/6 genome but absent from the Celera mixed-strain assembly, which excludes C57BL/6 data and differs from the NIH build with respect to the organization of the α-defensin gene locus. Conversely, C57BL/6 mice lack the Crp1, -2, -4, and -6 peptides and their correspondingDefcr1, -2, -4, and -6genes, which are common to several mouse strains, including those of the Celera assembly. In C57BL/6 mice, α-defensin gene diversification appears to have occurred by tandem duplication of a multigene cassette that was not found in the mixed-strain assembly. Both mouse genome assemblies contain conserved α-defensin pseudogenes that are closely related to functional myeloid α-defensin genes in the rat, suggesting that the neutrophil α-defensin defect in mice resulted from progressive gene loss. Given the role of α-defensins in shaping the composition of the enteric microflora, such polymorphisms may influence outcomes in mouse models of disease or infection.
Cooperation between LepA and PlcH Contributes to theIn VivoVirulence and Growth ofPseudomonas aeruginosain Mice
Authors: Kida Yutaka , Shimizu Takashi , Kuwano Koichi 
Published: November 2010

ABSTRACTPseudomonas aeruginosa-derived large extracellular protease (LepA) and hemolytic phospholipase C (PlcH) are considered to play an important role in the pathogenicity of this organism. Although bacterial growth appears to be closely related to virulence, little is known about whether LepA and PlcH participate in the growth and virulence ofP. aeruginosa. In this study, we investigated whether LepA and PlcH contribute to the virulence and growth ofP. aeruginosausing a wild-type strain and mutants. The growth rate of the isogeniclepAsingle mutant was lower than that of the wild-type strain in a minimal medium containing serum albumin or hemoglobin as the sole carbon and nitrogen source. Furthermore, the growth rate of thelepA plcHdouble mutant decreased greatly compared with that of the wild-type strain in a minimal medium containing erythrocytes as a sole nutrient source for growth. Thus, these results indicate that cooperation between LepA and PlcH would contribute to the utilization of erythrocytes as a sole nutrient source for the growth ofP. aeruginosa. In addition, mouse infection experiments demonstrated that the virulence of thelepAandplcHsingle mutants was attenuated, and the numbers of the mutants were lower than the numbers of the wild-type strain in peritoneal lavage fluid and whole-blood specimens. In particular, the virulence and growth rate of thelepA plcHdouble mutant were markedly lower than those of the wild-type strain. Collectively, these results suggest that LepA and PlcH contribute to thein vivovirulence and growth ofP. aeruginosa.
Parallel Evolution in Pseudomonas aeruginosa over 39,000 Generations
In Vivo
Authors: Huse Holly K. , Kwon Taejoon , Zlosnik James E. A. , Speert David P. , Marcotte Edward M. , Whiteley Marvin 
Published: November 2010

ABSTRACT

The Gram-negative bacterium
Pseudomonas aeruginosa
is a common cause of chronic airway infections in individuals with the heritable disease cystic fibrosis (CF). After prolonged colonization of the CF lung,
P. aeruginosa
becomes highly resistant to host clearance and antibiotic treatment; therefore, understanding how this bacterium evolves during chronic infection is important for identifying beneficial adaptations that could be targeted therapeutically. To identify potential adaptive traits of
P. aeruginosa
during chronic infection, we carried out global transcriptomic profiling of chronological clonal isolates obtained from 3 individuals with CF. Isolates were collected sequentially over periods ranging from 3 months to 8 years, representing up to 39,000
in vivo
generations. We identified 24 genes that were commonly regulated by all 3
P. aeruginosa
lineages, including several genes encoding traits previously shown to be important for
in vivo
growth. Our results reveal that parallel evolution occurs in the CF lung and that at least a proportion of the traits identified are beneficial for
P. aeruginosa
chronic colonization of the CF lung.

IMPORTANCE
Deadly diseases like AIDS, malaria, and tuberculosis are the result of long-term chronic infections. Pathogens that cause chronic infections adapt to the host environment, avoiding the immune response and resisting antimicrobial agents. Studies of pathogen adaptation are therefore important for understanding how the efficacy of current therapeutics may change upon prolonged infection. One notorious chronic pathogen is
Pseudomonas aeruginosa
, a bacterium that causes long-term infections in individuals with the heritable disease cystic fibrosis (CF). We used gene expression profiles to identify 24 genes that commonly changed expression over time in 3
P. aeruginosa
lineages, indicating that these changes occur in parallel in the lungs of individuals with CF. Several of these genes have previously been shown to encode traits critical for
in vivo
-relevant processes, suggesting that they are likely beneficial adaptations important for chronic colonization of the CF lung.
Resveratrol: Challenges in Translation to the Clinic — A Critical Discussion
Authors: Subramanian Lalita , Youssef Sherry , Bhattacharya Saswati , Kenealey Jason , Polans Arthur S. , van Ginkel Paul R. 
Published: November 2010

AbstractLow cancer survival rates and the serious side effects often associated with current chemotherapeutics highlight the need for new and effective nontoxic anticancer agents. Since 1997 when Jang and colleagues first described resveratrol's ability to inhibit carcinogenesis, it has consistently proven effective at tumor inhibition in diverse human cancer models. This finding has raised the hope that resveratrol would pioneer a novel class of nontoxic chemotherapeutics. As a consequence of initial basic and preclinical studies, resveratrol is now being extensively promoted in the unregulated nutraceutical sector. However, some fundamental aspects of resveratrol's action need to be understood before it can be developed into a clinically viable anticancer drug. These areas pertain to the key mechanism(s) by which resveratrol potentiates its antitumor effects. Current research suggests that these mechanisms might be through novel pathways, requiring an understanding of cellular uptake, sentinel targets, and in vivo biological networks. The metabolism of resveratrol and its bioavailablity also warrant further consideration in light of recent in vitro and in vivo studies. Finally, we need to appreciate the sorts of information about resveratrol that may translate between different disease entities. We present a critical discussion of these issues and suggest important experiments that could pave the way to the successful translation of resveratrol to the clinic.Clin Cancer Res; 16(24); 5942–8. ©2010 AACR.
MS-275 Sensitizes TRAIL-Resistant Breast Cancer Cells, Inhibits Angiogenesis and Metastasis, and Reverses Epithelial-Mesenchymal Transition In vivo
Authors: Srivastava Rakesh K. , Kurzrock Razelle , Shankar Sharmila 
Published: November 2010

Abstract
Histone deacetylase (HDAC) inhibitors and tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) show promise for the treatment of cancers. The purpose of this study was to examine the molecular mechanisms by which HDAC inhibitor MS-275 sensitizes TRAIL-resistant breast cancer cells in vivo, inhibits angiogenesis and metastasis, and reverses epithelial-mesenchymal transition (EMT). BALB/c nude mice were orthotopically implanted with TRAIL-resistant invasive breast cancer MDA-MB-468 cells and treated intravenously with MS-275, TRAIL, or MS-275 followed by TRAIL, 4 times during first 3 weeks. Treatment of mice with TRAIL alone had no effect on tumor growth, metastasis, angiogenesis, and EMT. In comparison, MS-275 sensitized TRAIL-resistant xenografts by inducing apoptosis, inhibiting tumor cell proliferation, angiogenesis, metastasis, and reversing EMT. Treatment of nude mice with MS-275 resulted in downregulation of NF-κB and its gene products (cyclin D1, Bcl-2, Bcl-XL, VEGF, HIF-1α, IL-6, IL-8, MMP-2, and MMP-9) and upregulation of DR4, DR5, Bax, Bak, and p21/CIP1 in tumor cells. Furthermore, MS-275-treated mice showed significantly reduced tumor growth and decreased circulating vascular VEGFR2-positive endothelial cells, CD31-positive or von Willebrand factor–positive blood vessels, and lung metastasis compared with control mice. Interestingly, MS-275 caused “cadherin switch” and reversed EMT as shown by the upregulation of E-cadherin and downregulation of N-cadherin and transcription factors Snail, Slug, and ZEB1. In conclusion, sequential treatments of mice with MS-275 followed by TRAIL may target multiple pathways to reverse EMT and inhibit tumor progression, angiogenesis, and metastasis and represent a novel therapeutic approach to treat cancer. Mol Cancer Ther; 9(12); 3254–66. ©2010 AACR.