bluuebunny/crossref_metadata_2025 huggingface dataset:
A Novel Gene Cassette,
aacA43
, in a Plasmid-Borne Class 1 Integron
Authors: Partridge Sally R. , Thomas Lee C. , Ginn Andrew N. , Wiklendt Agnieszka M. , Kyme Pierre , Iredell Jonathan R.
Published: March 2011

A novel gene cassette,
aacA43
, was identified in the
aadB-aacA43-oxa10-smr2
cassette array in a class 1 integron. Like related aminoglycoside-(6′)-acetyltransferases, AacA43 confers clinically relevant resistance to kanamycin, tobramycin, and some less-used aminoglycosides but not to gentamicin. Although transferable on an IncL/M plasmid,
aacA43
was identified in only two different
Klebsiella pneumoniae
strains (14 isolates), one
Escherichia coli
strain (2 isolates), and one
Enterobacter cloacae
strain in a survey of patients in a Sydney intensive care unit in 2004-2005.
Saturability of Granulocyte Kill of Pseudomonas aeruginosa in a Murine Model of Pneumonia
Authors: Drusano G. L. , VanScoy B. , Liu W. , Fikes S. , Brown D. , Louie A.
Published: March 2011

Outcomes for patients with dense bacterial burdens, such as ventilator-associated pneumonia (VAP) patients, are often critically influenced by the adequacy of antimicrobial chemotherapy and by the response of the immune system, particularly the granulocytes. Little information is available about the quantitation of kill of organisms over time by granulocytes. In this investigation, we examined the impact of the baseline bacterial burden on the ability of granulocytes alone (without chemotherapy) to keep the number of organisms in check or to kill them over a 24-h period.
Pseudomonas aeruginosa
ATCC 27853 was the study organism, and we employed a murine pneumonia model (granulocyte replete) for the study. We found that the ability of the immune system to kill
P. aeruginosa
was saturable. The burden at which the system was half saturated was 2.15 × 10
6
± 2.66 × 10
6
CFU/g. Burdens greater than 10
7
CFU/g demonstrated net growth over 24 h. These findings suggest the need for aggressive chemotherapy early in the treatment of VAP to keep the burden from saturating the granulocytes. This should optimize the outcome for these seriously infected patients.
In Vitro Activity of Ceftazidime Combined with NXL104 versus Pseudomonas aeruginosa Isolates Obtained from Patients in Canadian Hospitals (CANWARD 2009 Study)
Authors: Walkty A. , DeCorby M. , Lagacé-Wiens P. R. S. , Karlowsky J. A. , Hoban D. J. , Zhanel G. G.
Published: March 2011

The
in vitro
activity of ceftazidime in combination with NXL104 versus 470
Pseudomonas aeruginosa
clinical isolates was evaluated using Clinical and Laboratory Standards Institute (CLSI) broth microdilution methods. Ceftazidime had MIC
90
s of 8 μg/ml and 32 μg/ml in the presence and absence of NXL104, respectively. Of 25 multidrug-resistant
P. aeruginosa
isolates, the percentages with a ceftazidime MIC of ≤8 μg/ml with and without NXL104 were 60% and 4%, respectively. These data suggest that the ceftazidime-NXL104 combination may prove useful for treating many
P. aeruginosa
infections.
Combinatorial Effect of Two Framework Mutations (E119V and I222L) in the Neuraminidase Active Site of H3N2 Influenza Virus on Resistance to Oseltamivir
Authors: Richard Mathilde , Ferraris Olivier , Erny Alexandra , Barthélémy Mendy , Traversier Aurélien , Sabatier Murielle , Hay Alan , Lin Yi Pu , Russell Rupert J. , Lina Bruno
Published: March 2011

Neuraminidase (NA) inhibitors (NIs) are the first line of defense against influenza virus. Reverse genetics experiments allow the study of resistance mechanisms by anticipating the impacts of mutations to the virus. To look at the possibility of an increased effect on the resistance phenotype of a combination of framework mutations, known to confer resistance to oseltamivir or zanamivir, with limited effect on virus fitness, we constructed 4 viruses by reverse genetics in the A/Moscow/10/99 H3N2 background containing double mutations in their neuraminidase genes: E119D+I222L, E119V+I222L, D198N+I222L, and H274Y+I222L (N2 numbering). Among the viruses produced, the E119D+I222L mutant virus was not able to grow without bacterial NA complementation and the D198N+I222L mutant and H274Y+I222L mutant were not stable after passages in MDCK cells. The E119V+I222L mutant was stable after five passages in MDCK cells. This E119V-and-I222L combination had a combinatorial effect on oseltamivir resistance. The total NA activity of the E119V+I222L mutant was low (5% compared to that of the wild-type virus). This drop in NA activity resulted from a decreased NA quantity in the virion in comparison to that of the wild-type virus (1.4% of that of the wild type). In MDCK-SIAT1 cells, the E119V+I222L mutant virus did not present a replicative advantage over the wild-type virus, even in the presence of oseltamivir. Double mutations combining two framework mutations in the NA gene still have to be monitored, as they could induce a high level of resistance to NIs, without impairing the NA affinity. Our study allows a better understanding of the diversity of the mechanisms of resistance to NIs.
Wild-Type MIC Distributions and Epidemiological Cutoff Values for Caspofungin and Aspergillus spp. for the CLSI Broth Microdilution Method (M38-A2 Document)
Authors: Espinel-Ingroff A. , Fothergill A. , Fuller J. , Johnson E. , Pelaez T. , Turnidge J.
Published: March 2011

Clinical breakpoints have not been established for mold testing. Epidemiologic cutoff values (ECVs) are available for six
Aspergillus
spp. and the triazoles, but not for caspofungin. Wild-type (WT) minimal effective concentration (MEC) distributions (organisms in a species-drug combination with no acquired resistance mechanisms) were defined in order to establish ECVs for six
Aspergillus
spp. and caspofungin. The number of available isolates was as follows: 1,691
A. fumigatus
, 432
A. flavus
, 192
A. nidulans
, 440
A. niger
, 385
A. terreus
, and 75
A. versicolor
isolates. CLSI broth microdilution MEC data gathered in five independent laboratories in Canada, Europe, and the United States were aggregated for the analyses. ECVs expressed in μg/ml that captured 95% and 99% of the modeled wild-type population were for
A. fumigatus
0.5 and 1,
A. flavus
0.25 and 0.5,
A. nidulans
0.5 and 0.5,
A. niger
0.25 and 0.25,
A. terreus
0.25 and 0.5, and
A. versicolor
0.25 and 0.5. Although caspofungin ECVs are not designed to predict the outcome of therapy, they may aid in the detection of strains with reduced antifungal susceptibility to this agent and acquired resistance mechanisms.
Dynamics of the Action of Biocides in Pseudomonas aeruginosa Biofilms
Authors: Bridier A. , Dubois-Brissonnet F. , Greub G. , Thomas V. , Briandet R.
Published: March 2011

The biocidal activity of peracetic acid (PAA) and benzalkonium chloride (BAC) on
Pseudomonas aeruginosa
biofilms was investigated by using a recently developed confocal laser scanning microscopy (CLSM) method that enables the direct and real-time visualization of cell inactivation within the structure. This technique is based on monitoring the loss of fluorescence that corresponds to the leakage of a fluorophore out of cells due to membrane permeabilization by the biocides. Although this approach has previously been used with success with various Gram-positive species, it is not directly applicable to the visualization of Gram-negative strains such as
P. aeruginosa
, particularly because of limitations regarding fluorescence staining. After adapting the staining procedure to
P. aeruginosa
, the action of PAA and BAC on the biofilm formed by strain ATCC 15442 was investigated. The results revealed specific inactivation patterns as a function of the mode of action of the biocides. While PAA treatment triggered a uniform loss of fluorescence in the structure, the action of BAC was first localized at the periphery of cell clusters and then gradually spread throughout the biofilm. Visualization of the action of BAC in biofilms formed by three clinical isolates then confirmed the presence of a delay in penetration, showing that diffusion-reaction limitations could provide a major explanation for the resistance of
P. aeruginosa
biofilms to this biocide. Biochemical analysis suggested a key role for extracellular matrix characteristics in these processes.
Bacteriophages LIMElight and LIMEzero of Pantoea agglomerans, Belonging to the “phiKMV-Like Viruses”
Authors: Adriaenssens Evelien M. , Ceyssens Pieter-Jan , Dunon Vincent , Ackermann Hans-Wolfgang , Van Vaerenbergh Johan , Maes Martine , De Proft Maurice , Lavigne Rob
Published: March 2011

Pantoea agglomeransis a common soil bacterium used in the biocontrol of fungi and bacteria but is also an opportunistic human pathogen. It has been described extensively in this context, but knowledge of bacteriophages infecting this species is limited. Bacteriophages LIMEzero and LIMElight ofP. agglomeransare lytic phages, isolated from soil samples, belonging to thePodoviridaeand are the firstPantoeaphages of this family to be described. The double-stranded DNA (dsDNA) genomes (43,032 bp and 44,546 bp, respectively) encode 57 and 55 open reading frames (ORFs). Based on the presence of an RNA polymerase in their genomes and their overall genome architecture, these phages should be classified in the subfamily of theAutographivirinae, within the genus of the “phiKMV-like viruses.” Phylogenetic analysis of all the sequenced members of theAutographivirinaesupports the classification of phages LIMElight and LIMEzero as members of the “phiKMV-like viruses” and corroborates the subdivision into the different genera. These data expand the knowledge ofPantoeaphages and illustrate the wide host diversity of phages within the “phiKMV-like viruses.”
Targeted Allele Replacement Mutagenesis of Corynebacterium pseudotuberculosis
Authors: Walker Caray A. , Donachie Willie , Smith David G. E. , Fontaine Michael C.
Published: March 2011

A two-step allele replacement mutagenesis procedure, using a conditionally replicating plasmid, was developed to allow the creation of targeted, marker-free mutations in
Corynebacterium pseudotuberculosis
. The relationship between homologous sequence length and recombination frequency was determined, and enhanced plasmid excision was observed due to the rolling-circle replication of the mutagenesis vector. Furthermore, an antibiotic enrichment procedure was applied to improve the recovery of mutants. Subsequently, as proof of concept, a marker-free,
cp40
-deficient mutant of
C. pseudotuberculosis
was constructed.
Functional Analysis of the
Trichoderma harzianum nox1
Gene, Encoding an NADPH Oxidase, Relates Production of Reactive Oxygen Species to Specific Biocontrol Activity against Pythium ultimum
Authors: Montero-Barrientos M. , Hermosa R. , Cardoza R. E. , Gutiérrez S. , Monte E.
Published: March 2011

The synthesis of reactive oxygen species (ROS) is one of the first events following pathogenic interactions in eukaryotic cells, and NADPH oxidases are involved in the formation of such ROS. The
nox1
gene of
Trichoderma harzianum
was cloned, and its role in antagonism against phytopathogens was analyzed in
nox1
-overexpressed transformants. The increased levels of
nox1
expression in these transformants were accompanied by an increase in ROS production during their direct confrontation with
Pythium ultimum
. The transformants displayed an increased hydrolytic pattern, as determined by comparing protease, cellulase, and chitinase activities with those for the wild type. In confrontation assays against
P. ultimum
the
nox1
-overexpressed transformants were more effective than the wild type, but not in assays against
Botrytis cinerea
or
Rhizoctonia solani
. A transcriptomic analysis using a
Trichoderma
high-density oligonucleotide (HDO) microarray also showed that, compared to gene expression for the interaction of wild-type
T. harzianum
and
P. ultimum
, genes related to protease, cellulase, and chitinase activities were differentially upregulated in the interaction of a
nox1
-overexpressed transformant with this pathogen. Our results show that
nox1
is involved in
T. harzianum
ROS production and antagonism against
P. ultimum
.
Genome Signatures of Escherichia coli O157:H7 Isolates from the Bovine Host Reservoir
Authors: Eppinger Mark , Mammel Mark K. , LeClerc Joseph E. , Ravel Jacques , Cebula Thomas A.
Published: March 2011

Cattle comprise a main reservoir of Shiga toxin-producing
Escherichia coli
O157:H7 (STEC). The significant differences in host prevalence, transmissibility, and virulence phenotypes among strains from bovine and human sources are of major interest to the public health community and livestock industry. Genomic analysis revealed divergence into three lineages: lineage I and lineage I/II strains are commonly associated with human disease, while lineage II strains are overrepresented in the asymptomatic bovine host reservoir. Growing evidence suggests that genotypic differences between these lineages, such as polymorphisms in Shiga toxin subtypes and synergistically acting virulence factors, are correlated with phenotypic differences in virulence, host ecology, and epidemiology. To assess the genomic plasticity on a genome-wide scale, we have sequenced the whole genome of strain EC869, a bovine-associated
E. coli
O157:H7 isolate. Comparative phylogenomic analysis of this key isolate enabled us to place accurately bovine lineage II strains within the genetically homogenous
E. coli
O157:H7 clade. Identification of polymorphic loci that are anchored both in the chromosomal backbone and horizontally acquired regions allowed us to associate bovine genotypes with altered virulence phenotypes and host prevalence. This study catalogued numerous novel lineage II-specific genome signatures, some of which appear to be associated intimately with the altered pathogenic potential and niche adaptation within the bovine rumen. The presented extended list of polymorphic markers is valuable in the development of a robust typing system critical for forensic, diagnostic, and epidemiological studies of this emerging human pathogen.
Grx4 Monothiol Glutaredoxin Is Required for Iron Limitation-Dependent Inhibition of Fep1
Authors: Jbel Mehdi , Mercier Alexandre , Labbé Simon
Published: March 2011

The expression of iron transport genes inSchizosaccharomyces pombeis controlled by the Fep1 transcription factor. When iron levels exceed those needed by the cells, Fep1 represses iron transport genes. In contrast, Fep1 is unable to bind chromatin under low-iron conditions, and that results in activation of genes involved in iron acquisition. Studies of fungi have revealed that monothiol glutaredoxins are required to inhibit iron-dependent transcription factors in response to high levels of iron. Here, we show that the monothiol glutaredoxin Grx4 plays an important role in the negative regulation of Fep1 activity in response to iron deficiency. Deletion of thegrx4+gene led to constitutive promoter occupancy by Fep1 and caused an invariable repression of iron transport genes. We found that Grx4 and Fep1 physically interact with each other. Grx4 contains an N-terminal thioredoxin (TRX)-like domain and a C-terminal glutaredoxin (GRX)-like domain. Deletion mapping analysis revealed that the TRX domain interacts strongly and constitutively with the C-terminal region of Fep1. As opposed to the TRX domain, the GRX domain associates weakly and in an iron-dependent manner with the N-terminal region of Fep1. Further analysis showed that Cys35 of Grx4 is required for the interaction between the Fep1 C terminus and the TRX domain, whereas Grx4 Cys172 is necessary for the association between the Fep1 N terminus and the GRX domain. Our results describe the first example of a monothiol glutaredoxin that acts as an inhibitory partner for an iron-regulated transcription factor under conditions of low iron levels.
A Chlamydia trachomatis OmcB C-Terminal Fragment Is Released into the Host Cell Cytoplasm and Is Immunogenic in Humans
Authors: Qi Manli , Gong Siqi , Lei Lei , Liu Quanzhong , Zhong Guangming
Published: March 2011

The
Chlamydia trachomatis
outer membrane complex protein B (OmcB) is an antigen with diagnostic and vaccine relevance. To further characterize OmcB, we generated antibodies against OmcB C-terminal (OmcBc) and N-terminal (OmcBn) fragments. Surprisingly, the anti-OmcBc antibody detected dominant signals in the host cell cytosol, while the anti-OmcBn antibody exclusively labeled intrainclusion signals in
C. trachomatis
-infected cells permeabilized with saponin. Western blot analyses revealed that OmcB was partially processed into OmcBc and OmcBn fragments. The processed OmcBc was released into host cell cytosol, while the OmcBn and remaining full-length OmcB were retained within the chlamydial inclusions. The organism-associated OmcB epitopes became detectable only after the
C. trachomatis
-infected cells were permeabilized with strong detergents such as SDS. However, the harsh permeabilization conditions also led to the leakage of the already secreted OmcBc and chlamydia-secreted protease (CPAF) out of the host cells. The OmcBc processing and release occurred in all biovars of
C. trachomatis
. Moreover, the released OmcBc but not the retained OmcBn was highly immunogenic in
C. trachomatis
-infected women, which is consistent with the concept that exposure of chlamydial proteins to host cell cytosol is accompanied by increased immunogenicity. These observations have provided important information for further exploring/optimizing OmcB as a target for the development of diagnosis methods and vaccines.
Vitamin D-Mediated Induction of Innate Immunity in Gingival Epithelial Cells
Authors: McMahon Laura , Schwartz Kyell , Yilmaz Ozlem , Brown Eleith , Ryan Lisa K. , Diamond Gill
Published: March 2011

Human gingival epithelial cells (GEC) produce peptides, such as β-defensins and the cathelicidin LL-37, that are both antimicrobial and that modulate the innate immune response. In myeloid and airway epithelial cells, the active form of vitamin D3[1,25(OH)2D3] increases the expression and antibacterial activity of LL-37. To examine the activity of vitamin D on the innate immune defense of the gingival epithelium, cultured epithelial cells were treated with either 10−8M 1,25(OH)2D3or ethanol for up to 24 h. A time-dependent induction of LL-37 mRNA up to 13-fold at 24 h in both standard monolayer and three-dimensional cultures was observed. Induction of the vitamin D receptor and the 1-α-hydroxylase genes was also observed. The hydroxylase was functional, as LL-37 induction was observed in response to stimulation by 25(OH)D3. Through microarray analysis of other innate immune genes, CD14 expression increased 4-fold, and triggering receptor expressed on myeloid cells-1 (TREM-1) was upregulated 16-fold after 24 h of treatment with 1,25(OH)2D3. TREM-1 is a pivotal amplifier of the innate immune response in macrophages, leading to increased production by inflammatory response genes. Activation of TREM-1 on the GEC led to an increase in interleukin-8 (IL-8) mRNA levels. Incubation of three-dimensional cultures with 1,25(OH)2D3led to an increase in antibacterial activity against the periodontal pathogenAggregatibacter actinomycetemcomitanswhen the bacteria were added to the apical surface. This study is the first to demonstrate the effect of vitamin D on antibacterial defense of oral epithelial cells, suggesting that vitamin D3could be utilized to enhance the innate immune defense in the oral cavity.
Role of Fibronectin-Binding Proteins A and B inIn VitroCellular Infections andIn VivoSeptic Infections by Staphylococcus aureus
Authors: Shinji Hitomi , Yosizawa Yukio , Tajima Akiko , Iwase Tadayuki , Sugimoto Shinya , Seki Keiko , Mizunoe Yoshimitsu
Published: March 2011

Fibronectin-binding protein A (FnBPA) and FnBPB are important adhesins forStaphylococcus aureusinfection. We constructedfnbAand/orfnbBmutant strains fromS. aureusSH1000, which possesses intactrsbU, and studied the role of these adhesins inin vitroandin vivoinfections. In intravenous infection, allfnbmutants caused a remarkable reduction in the colonization rate in kidneys and the mortality rate of mice.fnbBmutant caused a more severe decrease in body weight than that caused byfnbAmutant. Serum levels of interleukin-6 and nuclear factor κB (NF-κB) activation in spleen cells were remarkably reduced infnbAorfnbA fnbBmutant infections; however, there was no significant reduction infnbBmutant infections. Inin vitrocellular infection, FnBPA was shown to be indispensable for adhesion to and internalization by nonprofessional phagocytic cells upon ingestion by inflammatory macrophages and NF-κB activation. However, both FnBPs were required for efficient cellular responses. The results showed that FnBPA is more important forin vitroandin vivoinfections; however, cooperation between FnBPA and FnBPB is indispensable for the induction of severe infection resulting in septic death.
MyD88 Signaling Is Required for Efficient Innate and Adaptive Immune Responses to Paracoccidioides brasiliensis Infection
Authors: Loures Flávio V. , Pina Adriana , Felonato Maíra , Feriotti Claudia , de Araújo Eliseu F. , Calich Vera L. G.
Published: March 2011

The mechanisms that govern the initial interaction betweenParacoccidioides brasiliensis, a primary dimorphic fungal pathogen, and cells of the innate immunity need to be clarified. Our previous studies showed that Toll-like receptor 2 (TLR2) and TLR4 regulate the initial interaction of fungal cells with macrophages and the pattern of adaptive immunity that further develops. The aim of the present investigation was to assess the role of MyD88, an adaptor molecule used by TLRs to activate genes of the inflammatory response in pulmonary paracoccidioidomycosis. Studies were performed with normal and MyD88−/−C57BL/6 mice intratracheally infected withP. brasiliensisyeast cells. MyD88−/−macrophages displayed impaired interaction with fungal yeast cells and produced low levels of IL-12, MCP-1, and nitric oxide, thus allowing increased fungal growth. Compared with wild-type (WT) mice, MyD88−/−mice developed a more severe infection of the lungs and had marked dissemination of fungal cells to the liver and spleen. MyD88−/−mice presented low levels of Th1, Th2, and Th17 cytokines, suppressed lymphoproliferation, and impaired influx of inflammatory cells to the lungs, and this group of cells comprised lower numbers of neutrophils, activated macrophages, and T cells. Nonorganized, coalescent granulomas, which contained high numbers of fungal cells, characterized the severe lesions of MyD88−/−mice; the lesions replaced extensive areas of several organs. Therefore, MyD88−/−mice were unable to control fungal growth and showed a significantly decreased survival time. In conclusion, our findings demonstrate that MyD88 signaling is important in the activation of fungicidal mechanisms and the induction of protective innate and adaptive immune responses againstP. brasiliensis.
Serine Protease PrtA from Streptococcus pneumoniae Plays a Role in the Killing of S. pneumoniae by Apolactoferrin
Authors: Mirza Shaper , Wilson Landon , Benjamin William H. , Novak Jan , Barnes Stephen , Hollingshead Susan K. , Briles David E.
Published: March 2011

It is known that apolactoferrin, the iron-free form of human lactoferrin, can kill many species of bacteria, including
Streptococcus pneumoniae
. Lactoferricin, an N-terminal peptide of apolactoferrin, and fragments of it are even more bactericidal than apolactoferrin. In this study we found that apolactoferrin must be cleaved by a serine protease in order for it to kill pneumococci. The serine protease inhibitors were able to block killing by apolactoferrin but did not block killing by a lactoferrin-derived peptide. Thus, the killing of pneumococci by apolactoferrin appears to require a protease to release a lactoferricin-like peptide(s). Incubation of apolactoferrin with growing pneumococci resulted in a 12-kDa reduction in its molecular mass, of which about 7 to 8 kDa of the reduction was protease dependent. Capsular type 2 and 19F strains with mutations in the gene encoding the major cell wall-associated serine protease,
prtA
, lost much of their ability to degrade apolactoferrin and were relatively resistant to killing by apolactoferrin (
P
< 0.001). Recombinant PrtA was also able to cleave apolactoferrin, reducing its mass by about 8 kDa, and greatly enhance the killing activity of the solution containing the apolactoferrin and its cleavage products. Mass spectroscopy revealed that PrtA makes a major cut between amino acids 78 and 79 of human lactoferrin, removing the N-terminal end of the molecule (about 8.6 kDa). The simplest interpretation of these data is that the mechanism by which apolactoferrin kills
Streptococcus pneumoniae
requires the release of a lactoferricin-like peptide(s) and that it is this peptide(s), and not the intact apolactoferrin, which kills pneumococci.
The Collagen-Binding Protein Cnm Is Required for Streptococcus mutans Adherence to and Intracellular Invasion of Human Coronary Artery Endothelial Cells
Authors: Abranches Jacqueline , Miller James H. , Martinez Alaina R. , Simpson-Haidaris Patricia J. , Burne Robert A. , Lemos José A.
Published: March 2011

Streptococcus mutans
is considered the primary etiologic agent of dental caries, a global health problem that affects 60 to 90% of the population, and a leading causative agent of infective endocarditis. It can be divided into four different serotypes (
c
,
e
,
f
, and
k
), with serotype
c
strains being the most common in the oral cavity. In this study, we demonstrate that in addition to OMZ175 and B14, three other strains (NCTC11060, LM7, and OM50E) of the less prevalent serotypes
e
and
f
are able to invade primary human coronary artery endothelial cells (HCAEC). Invasive strains were also significantly more virulent than noninvasive strains in the
Galleria mellonella
(greater wax worm) model of systemic disease. Interestingly, the invasive strains carried an additional gene,
cnm
, which was previously shown to bind to collagen and laminin
in vitro
. Inactivation of
cnm
rendered the organisms unable to invade HCAEC and attenuated their virulence in
G. mellonella
. Notably, the
cnm
knockout strains did not adhere to HCAEC as efficiently as the parental strains did, indicating that the loss of the invasion phenotype observed for the mutants was linked to an adhesion defect. Comparisons of the invasive strains and their respective
cnm
mutants did not support a correlation between biofilm formation and invasion. Thus, Cnm is required for
S. mutans
invasion of endothelial cells and possibly represents an important virulence factor of
S. mutans
that may contribute to cardiovascular infections and pathologies.
Differential MicroRNA Expression in Experimental Cerebral and Noncerebral Malaria
Authors: El-Assaad Fatima , Hempel Casper , Combes Valéry , Mitchell Andrew J. , Ball Helen J. , Kurtzhals Jørgen A. L. , Hunt Nicholas H. , Mathys Jean-Marie , Grau Georges E. R.
Published: March 2011

MicroRNAs (miRNAs) are posttranscriptional regulatory molecules that have been implicated in the regulation of immune responses, but their role in the immune response toPlasmodiuminfection is unknown. We studied the expression of selected miRNAs following infection of CBA mice withPlasmodium bergheiANKA (PbA), which causes cerebral malaria (CM), orPlasmodium bergheiK173 (PbK), which causes severe malaria but without cerebral complications, termed non-CM. The differential expression profiles of selected miRNAs (let-7i, miR-27a, miR-150, miR-126, miR-210, and miR-155) were analyzed in mouse brain and heart tissue by quantitative reverse transcription-PCR (qRT-PCR). We identified three miRNAs that were differentially expressed in the brain of PbA-infected CBA mice: let7i, miR-27a, and miR-150. In contrast, no miRNA changes were detected in the heart, an organ with no known pathology during acute malaria. To investigate the involvement of let-7i, miR-27a, and miR-150 in CM-resistant mice, we assessed the expression levels in gamma interferon knockout (IFN-γ−/−) mice on a C57BL/6 genetic background. The expression of let-7i, miR-27a, and miR-150 was unchanged in both wild-type (WT) and IFN-γ−/−mice following infection. Overexpression of these three miRNAs during PbA, but not PbK, infection in WT mice may be critical for the triggering of the neurological syndrome via regulation of their potential downstream targets. Our data suggest that in the CBA mouse at least, miRNA may have a regulatory role in the pathogenesis of severe malaria.
SpyA, a C3-Like ADP-Ribosyltransferase, Contributes to Virulence in a Mouse Subcutaneous Model of Streptococcus pyogenes Infection
Authors: Hoff Jessica S. , DeWald Mark , Moseley Steve L. , Collins Carleen M. , Voyich Jovanka M.
Published: March 2011

Streptococcus pyogenesis an important human pathogen with an expansive repertoire of verified and putative virulence factors. Here we demonstrate that a mutant deficient in the production of the streptococcal ADP-ribosyltransferase SpyA generates lesions of reduced size in a subcutaneous mouse infection model. At early stages of infection, when the difference in lesion size is first established, inflamed tissue isolated from lesions of mice infected withspyAmutant bacteria has higher levels of mRNA encoding the chemokines CXCL1 and CCL2 than does tissue isolated from mice infected with wild-type bacteria. In addition, at these early times, the mRNA levels for the gene encoding the intermediate filament vimentin are higher in the mutant-infected tissue. As wound resolution progresses, mRNA levels of the gene encoding matrix metallopeptidase 2 are lower in mutant-infected tissue. Furthermore, we demonstrate that thespyAmutant is internalized more efficiently than wild-type bacteria by HeLa cells. We conclude that SpyA contributes to streptococcal pathogenesis in the mouse subcutaneous infection model. Our observations suggest that the presence of SpyA delays wound healing in this model.
Lcl of Legionella pneumophila Is an Immunogenic GAG Binding Adhesin That Promotes Interactions with Lung Epithelial Cells and Plays a Crucial Role in Biofilm Formation
Authors: Duncan Carla , Prashar Akriti , So Jannice , Tang Patrick , Low Donald E. , Terebiznik Mauricio , Guyard Cyril
Published: March 2011

Legionellosis is mostly caused byLegionella pneumophilaand is defined by a severe respiratory illness with a case fatality rate ranging from 5 to 80%.In vitroandin vivo, interactions ofL. pneumophilawith lung epithelial cells are mediated by the sulfated glycosaminoglycans (GAGs) of the host extracellular matrix. In this study, we have identified severalLegionellaheparin binding proteins. We have shown that one of these proteins, designated Lcl, is a polymorphic adhesin ofL. pneumophilathat is produced during legionellosis. Homologues of Lcl are ubiquitous inL. pneumophilaserogroups but are undetected in otherLegionellaspecies. Recombinant Lcl binds to GAGs, and a Δlpg2644mutant demonstrated reduced binding to GAGs and human lung epithelial cells. Importantly, we showed that the Δlpg2644strain is dramatically impaired in biofilm formation. These data delineate the role of Lcl in the GAG binding properties ofL. pneumophilaand provide molecular evidence regarding its role inL. pneumophilaadherence and biofilm formation.
CD4+T Cells Mediate the Protective Effect of the Recombinant Asp f3-Based Anti-Aspergillosis Vaccine
Authors: Diaz-Arevalo Diana , Bagramyan Karine , Hong Teresa B. , Ito James I. , Kalkum Markus
Published: March 2011

The mortality and morbidity caused by invasive aspergillosis present a major obstacle to the successful treatment of blood cancers with hematopoietic cell transplants. Patients who receive hematopoietic cell transplants are usually immunosuppressed for extended periods, and infection with the ubiquitous moldAspergillus fumigatusis responsible for most cases of aspergillosis. Previously, we demonstrated that vaccination with recombinant forms of theA. fumigatusprotein Asp f3 protected cortisone acetate-immunosuppressed mice from experimentally induced pulmonary aspergillosis. Here, we investigated the vaccine's protective mechanism and evaluated in particular the roles of antibodies and T cells. After vaccination, Asp f3-specific preinfection IgG titers did not significantly differ between surviving and nonsurviving mice, and passive transfer of anti-Asp f3 antibodies did not protect immunosuppressed recipients from aspergillosis. We experimentally confirmed Asp f3's predicted peroxisomal localization inA. fumigatushyphae. We found that fungal Asp f3 is inaccessible to antibodies, unless both cell walls and membranes have been permeabilized. Antibody-induced depletion of CD4+T cells reduced the survival of recombinant Asp f3 (rAsp f3)-vaccinated mice to nonimmune levels, and transplantation of purified CD4+T cells from rAsp f3-vaccinated mice into nonimmunized recipients transferred antifungal protection. In addition, residues 60 to 79 and 75 to 94 of Asp f3 contain epitopes that induce proliferation of T cells from vaccinated survivors. Vaccine-primed CD4+T cells are not expected to clear the fungal pathogen directly; however, they may locally activate immunosuppressed phagocytes that elicit the antifungal effect.
Methodological Issues in Evaluating Auricular Acupuncture Therapy for Problems Arising from the Use of Drugs and Alcohol
Authors: Cowan David
Published: March 2011

Auricular acupuncture is an accessible, non-confrontational therapy that appears to be effective when used in drug and alcohol treatment facilities, hospitals and prisons in the UK, Europe and the USA. Despite being popular, research evidence on its effectiveness is lacking, and as a result services are underfunded and risk being withdrawn.

There are methodological problems in researching auricular acupuncture. In these days of evidence-based medicine, most studies in this area are explanatory randomised controlled trials, which is limited in capturing the complete benefits of the intervention. Furthermore, there is lack of consensus over definitions of the concept of ‘addiction’ and whether or not this should be perceived as a ‘disease’ that can be ‘cured’ by an intervention such as auricular acupuncture. Basic concepts such as these need to inform development of outcome measures, which should include retention of clients in treatment as an indicator of success.

It is argued here that the best approach will integrate research on physical effects with research on subjective experience of those with drug and alcohol problems. The challenge is to design large scale, high quality, pragmatic randomised controlled trials to assess the effectiveness of auricular acupuncture over the longer term in settings that mimic the delivery of treatment in practice and are informed by acupuncture's own diagnostic traditions, using a combination of objective, quantitative methods and subjective, qualitative methods.
Inter-endoscopist agreement in diagnosis of Barrett's oesophagus
Authors: Doherty Glen A , Cheriyan Danny G , Leyden Jan E , O'Dowd John F , Murray Frank E , Patchett Stephen E
Published: March 2011

Objective

To assess how interpretation of abnormalities at the oesophago-gastric junction (OGJ) when making a diagnosis of Barrett's oesophagus (BO) varies between endoscopists and to examine the impact of the endoscopy experience on these decisions.

Design/setting

Members of the Irish Society of Gastroenterology who regularly perform gastroscopy were invited to participate in a web based image assessment study.

Interventions

Questions were posed to ascertain level of endoscopy experience, and participants were asked to indicate the presence or absence of BO in 12 endoscopic images of the OGJ.

Outcome measures

Primary outcome was overall level of agreement in responses and relationship to endoscopy experience.

Results

The responses of 65 clinicians regularly performing gastroscopy were analysed. In 3/12 images, showing typical long segment BO, there was a strong consensus on the endoscopic diagnosis (>95% agreement). However, agreement was fair to poor (κ for multiple raters, 0.31) on the presence or absence of short BO segments at endoscopy. Minimal differences were observed between experienced endoscopists (individuals with >10 years' endoscopy experience) and less experienced counterparts in the threshold for BO diagnosis. Inter-endoscopist agreement overall was not significantly better within the more experienced group.

Conclusion

The study demonstrates low interobserver agreement in endoscopic diagnosis of (short segment) BO, even among experienced endoscopists. Given the costs associated with endoscopic surveillance of BO, prompt efforts to promote consensus diagnosis and improve agreement are required as an important quality improvement measure in this area.
Observed use of tethers in forward-facing child restraint systems
Authors: Jermakian Jessica S , Wells JoAnn K
Published: March 2011

Background

Use of top tethers with forward-facing child restraints is a simple way for parents to keep their children safer when travelling in passenger vehicles, but tether use remains low.

Objectives

To obtain an updated estimate of top tether use.

Methods

Data on forward-facing child restraints were collected through an observational survey in the Washington DC metropolitan area during July–August 2010. The study sample included all forward-facing restraints that were installed in parked passenger vehicles and visible such that tether use could be observed. For each restraint, certified child passenger safety technicians collected information on the vehicle, seat row, restraint position, and tether.

Results

A total of 1321 cars, minivans, pickups, and sport utility vehicles, with a total of 1543 forward-facing child restraints, were observed. Tethers were used with 43.0% of all forward-facing child restraints. Tether use was similar (42.7–45.4%) among cars, minivans, and sport utility vehicles but lower (17.2%) for pickups. Tether use was higher (47.5%) for 2001 and newer vehicles, but dropped to 43.0% when only taut installations were considered.

Conclusions

Despite LATCH education campaigns and the increased availability of tether anchors, observed tether use was less than 50%. Tether use was even lower in older vehicles, yet many children continue to travel in these vehicles. If tether anchors are unavailable, parents should be encouraged to retrofit vehicle seating positions. Because many child restraints are still installed with vehicle seat belts, efforts to educate parents on the importance of tether use regardless of installation method may be warranted.
The reference interval of thyroid-stimulating hormone in Hong Kong Chinese
Authors: Chan Angel O K , Iu Y P , Shek C C
Published: March 2011

Aim

The upper reference limit of thyroid-stimulating hormone (TSH) is critical for defining patients with subclinical hypothyroidism, a condition which carries a higher risk of progression to overt hypothyroidism and adverse cardiovascular events. Yet, there is a lack of consensus on its absolute value, and data in non-pregnant adult Chinese are lacking.

Methods

Apparently healthy and drug-free local adult Chinese were recruited by completing health questionnaires. Their serum samples were tested for TSH, free thyroxine (FT4), thyroglobulin antibody and thyroid peroxidase antibody levels. After excluding subjects with thyroid antibodies, the TSH level was log-transformed, and the reference limits were defined as mean±1.96SD. The 2.5th and 97.5th percentiles of FT4 were also calculated.

Results

Serum samples from 212 subjects were used in this study. 51 subjects were seropositive to thyroglobulin antibody, 31 were seropositive to thyroid peroxidase antibody, and 27 were seropositive to both. The reference intervals after excluding subjects seropositive to thyroid antibodies were: TSH: 0.68–3.70 mIU/l; FT4: 13.5–21.3 pmol/l (male) and 12.6–19.7 pmol/l (female). Including subjects with thyroid antibodies only minimally changed the reference intervals of these hormones.

Conclusion

The authors have set up the reference interval of TSH for the local population, and their findings also suggest that the importance of excluding subjects with thyroid antibodies in the reference population should not be overemphasised. Moreover, the international authorities should consider recommending percentile-equivalent action limits instead of an absolute cut-off on TSH for categorisation of different types of thyroid dysfunction.
Risk factors for chlamydial infection in chlamydia contacts: a questionnaire-based study
Authors: Schembri Gabriel , Schober Paul
Published: March 2011

Background and methodology

Treatment of individuals with chlamydial infection and their sexual partners is an important aspect of reproductive health care. Partners of infected individuals are currently offered ‘epidemiological treatment’, which means that they are offered antibiotic treatment at their first visit without waiting for the result of their chlamydia test. We carried out a study to identify the risk factors for chlamydial infection in partners of infected individuals. Individuals attending a genitourinary clinic as chlamydia contacts were identified and asked to complete a questionnaire about their relationship with the index case and their prior sexual history. The result of their chlamydia test was then analysed against those variables.

Results

A total of 115 chlamydia contacts were analysed in this study; 60 (52%) were found to be positive for chlamydial infection. In a multivariate analysis, young age, more than one episode of sexual intercourse with the infected partner and a greater total number of sexual partners were associated with a positive chlamydia result. A prediction model for chlamydial infection using these risk factors had a discriminatory ability quantified by an area under the curve (AUC) of 0.76 (95% CI 0.66–0.85).

Discussion and conclusions

The risk factors identified can be used when discussing epidemiological treatment with individuals who attend sexual health services as chlamydia contacts, or to target clinic resources to a higher-risk group. Larger studies will be necessary to assess the benefits and risks of changing to a policy of offering epidemiologic treatment to ‘high-risk’ contacts only, identified using a predictive model such as the one described here.
Women in Cairo, Egypt and their risk factors for unmet contraceptive need: a community-based study
Authors: Kotb Mohammed Mahmoud , Bakr Iman , Ismail Nanees A , Arafa Naglaa , El-Gewaily Mohamed
Published: March 2011

Background and methodology

Although modern family planning methods are readily available in Egypt at low cost, a considerable proportion of women still have an unmet contraceptive need. The aim of this study was to detect the risk factors of unmet contraceptive need among married women in the childbearing period in an underprivileged area in Cairo with high population density. A survey of 2340 women in the Marg district of Eastern Cairo was conducted by means of home interviews. For every woman identified as having an unmet contraceptive need (n=174), the next two women identified with met contraceptive need were selected as controls (n=348).

Results

The prevalence of unmet need was 7.4%. Risk factors identified were: belief that contraception is religiously prohibited (OR 2.08, 95% CI 1.06–4.09); poor interspousal communication about the desired number of children (OR 2.59, 95% CI 1.40–4.79); husband opposition to contraceptive use (OR 2.96, 95% CI 1.47–5.97); a previous history of unwanted pregnancy (OR 2.98, 95% CI 1.73–5.14); and experiencing side effects from previous contraceptive use (OR 5.69, 95% CI 3.46–9.37).

Conclusions

The authors propose training physicians to identify and counsel women who experience contraceptive side effects and/or a previous unwanted pregnancy, as well as the transmission of clear media messages on the religious acceptability of contraceptive use.
Premature ovarian failure
Authors: Maclaran Kate , Panay Nick
Published: March 2011

Premature ovarian failure (POF) is the occurrence of amenorrhoea, elevated gonadotrophins and hypoestrogenism in women under 40 years of age. It has important physical and psychological consequences and is increasingly common due to improved survival following treatment for malignancy. Despite this, it remains a poorly understood condition. Here we review the presentation and investigation of POF, discuss recent advances in the management of affected women, and suggest how our knowledge of the condition could be improved.
Knowledge and attitudes of 52 UK pet rabbit owners at the point of sale
Authors: Edgar J. L. , Mullan S. M.
Published: March 2011

The aim of this study was to determine the knowledge and attitudes of pet rabbit owners at the time of buying their rabbit(s) and to investigate factors influencing the planned husbandry and housing of their rabbit(s). A questionnaire was used to assess the impact of demographics, knowledge and attitudes on the likelihood that respondents would neuter their rabbit(s), feed them an appropriate diet, house them in appropriately sized housing and provide them with an appropriate companion. Knowledge and attitudes were significant factors in whether respondents planned to neuter their rabbit(s) and provide them with an appropriate companion. The attribution of secondary emotions to rabbits was associated with plans to feed a mix‐type diet. The majority of owners had carried out prior research into pet rabbits, but owners had a limited knowledge of the needs of rabbits, particularly with respect to their diet and social needs. Respondents who had decided to purchase a rabbit on the day were less likely to intend to get their rabbit neutered than those who had taken more time to decide to buy a rabbit.
Assessment of feline blood for transfusion purposes in the Dublin area of Ireland
Authors: Juvet F. , Brennan S. , Mooney C. T.
Published: March 2011

The prevalence of A, B and AB blood types and of feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV) infection was determined in cats in Ireland, in order to determine risk factors for blood taken for transfusion purposes. EDTA blood samples were available from 137 non‐pedigree cats and 39 pedigree cats (91 females and 85 males, aged four months to 15.0 years) in the Dublin area of Ireland. Of the 176 EDTA blood samples obtained, 112 (from 92 healthy cats and 20 sick cats) were tested for the presence of both FIV antibodies and FeLV antigens. Blood typing was performed using an immunochromatographic cartridge (CHROM; Alvedia). Testing for FIV and FeLV was performed by ELISA (SNAP FIV/FeLV Combo Test; Idexx Laboratories). Of the 39 pedigree cats, the majority (38 [97.4 per cent]) was type A, and only one (2.6 per cent) was type B. Of the 137 non‐pedigree cats, the majority (116 [84.7 per cent]) was type A, 20 (14.6 per cent) were type B, and one (0.7 per cent) was type AB. Of the 92 healthy cats tested, the prevalence of FIV and FeLV positivity was 4.35 and 1.09 per cent, respectively. None of the 20 sick cats tested was FIV‐positive; two (10 per cent) of the 20 sick cats were FeLV‐positive.
BIONIC FACE RECOGNITION USING GABOR TRANSFORMATION
Authors: HE GUANGHUI , TANG YUANYAN , FANG BIN , WANG Patrick S. P.
Published: March 2011

In this paper, we propose a bionic face recognition method based on Gabor feature. First, Gabor features are extracted from face images, followed by dimensionality reduction using 2DPCA algorithm, which serves as the feature vectors of the proposed method. Finally, the bionic classifier is trained for classification. The experiment on AR and PIE face database is reported to show the effectiveness of the proposed method and compare it with Gabor-2DPCA algorithm and Gabor-PCA algorithm.