bluuebunny/crossref_metadata_2025_split huggingface dataset:
EspJ Is a Prophage-Carried Type III Effector Protein of Attaching and Effacing Pathogens That Modulates Infection Dynamics
Authors: Dahan Sivan , Wiles Siouxsie , La Ragione Roberto M. , Best Angus , Woodward Martin J. , Stevens Mark P. , Shaw Robert K. , Chong Yuwen , Knutton Stuart , Phillips Alan , Frankel Gad 
Published: January 2005

ABSTRACT

Enterohemorrhagic
Escherichia coli
, enteropathogenic
E. coli
, and
Citrobacter rodentium
are highly adapted enteropathogens that successfully colonize their host's gastrointestinal tract via the formation of attaching and effacing (A/E) lesions. These pathogens utilize a type III secretion system (TTSS) apparatus, encoded by the locus of enterocyte effacement, to translocate bacterial effector proteins into epithelial cells. Here, we report the identification of EspJ (
E. coli
-secreted protein J), a translocated TTSS effector that is carried on the 5′ end of the cryptic prophage CP-933U. Infection of epithelial cells in culture revealed that EspJ is not required for A/E lesion activity in vivo and ex vivo. However, in vivo studies performed with mice demonstrated that EspJ possesses properties that influence the dynamics of clearance of the pathogen from the host's intestinal tract, suggesting a role in host survival and pathogen transmission.
Identification of an Iron-Regulated Hemin-Binding Outer Membrane Protein, HupO, in
Vibrio fluvialis
: Effects on Hemolytic Activity and the Oxidative Stress Response
Authors: Ahn Sun-Hee , Han Jeong-Hyun , Lee Jong-Hee , Park Kee-Jai , Kong In-Soo 
Published: January 2005

ABSTRACT

In pathogenic bacteria, iron acquisition is important for colonization and proliferation in the host under iron-limited conditions. The ability of
Vibrio
spp. to acquire iron is often critical to their virulence, causing gastroenteritis or excessive watery diarrhea in humans. In the study described here, we cloned the 2,100-bp heme utilization protein gene
hupO
in
Vibrio fluvialis
. HupO had high homology to iron-regulated outer membrane receptor proteins in
Vibrio
sp. and contained motifs that are common to bacterial heme receptors, including a consensus TonB box, a FRAP domain, and an NPNL domain. To characterize the hemin-binding activity of HupO, we purified the recombinant HupO protein (rHupO) from
Escherichia coli
by using an overexpression system. HupO was found to bind to hemin but not to hemoglobin. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting demonstrated that the 77-kDa outer membrane protein HupO of
V. fluvialis
was induced under iron-restricted conditions. We constructed a
hupO
mutant, HP1, to investigate the biochemical function of HupO in
V. fluvialis
. The hemolytic activity of HP1 was reduced compared to that of wild-type cells and, when exposed to hydrogen peroxide, significantly lower numbers of HP1 survived than was the case in the wild type. These results suggest that HupO is associated with virulence expression in
V. fluvialis
through stimulation of hemolysin production and resistance to oxidative stress. In experimentally infected mice, the 50% lethal dose value of the wild-type was lower than that of the mutant, HP1.
Monoacyl Lipoteichoic Acid from Pneumococci Stimulates Human Cells but Not Mouse Cells
Authors: Kim Je Hak , Seo Hoseong , Han Seung Hyun , Lin Jisheng , Park Moon-Kook , Sorensen Uffe B. S. , Nahm Moon H. 
Published: January 2005

ABSTRACTWe have developed a method for obtaining pneumococcal lipoteichoic acid (LTA) with none, one, or two acyl chains. Anion-exchange chromatography at pH 9.5 yields pneumococcal LTA (labeled LTA-9.5) that has a mass spectrum identical to that of pre-ion-exchange LTA and loses 500 mass units after deacylation by alkali hydrolysis. Anion exchange at pH 10.5 produces LTA (labeled LTA-10.5) with mass peaks that are 264 mass units lower than those of pre-ion-exchange LTA, and deacylation of LTA-10.5 by alkali hydrolysis reduces the mass by only 239 mass units. This result indicates that LTA-10.5 has lost one of the two acyl chains, whereas LTA-9.5 has both acyl chains. When the biological properties of LTA-9.5 and LTA-10.5 are examined with mouse cells, only LTA-9.5 (and not LTA-10.5) is able to stimulate mouse cells to produce tumor necrosis factor alpha, interleukin-1β, and nitric oxide. In contrast, both LTA-9.5 and LTA-10.5 can stimulate human cells. LTA became inactive when both acyl chains were removed. Thus, acyl chains are critical for LTA function, and small variations in acyl chains can alter biological properties of LTA.
Staphylococcus aureus
Virulence Factors Identified by Using a High-Throughput
Caenorhabditis elegans-
Killing Model
Authors: Begun Jakob , Sifri Costi D. , Goldman Samuel , Calderwood Stephen B. , Ausubel Frederick M. 
Published: January 2005

ABSTRACT

Staphylococcus aureus
is an important human pathogen that is also able to kill the model nematode
Caenorhabditis elegans
. We constructed a 2,950-member Tn
917
transposon insertion library in
S. aureus
strain NCTC 8325. Twenty-one of these insertions exhibited attenuated
C. elegans
killing, and of these, 12 contained insertions in different genes or chromosomal locations. Ten of these 12 insertions showed attenuated killing phenotypes when transduced into two different
S. aureus
strains, and 5 of the 10 mutants correspond to genes that have not been previously identified in signature-tagged mutagenesis studies. These latter five mutants were tested in a murine renal abscess model, and one mutant harboring an insertion in
nagD
exhibited attenuated virulence. Interestingly, Tn
917
was shown to have a very strong bias for insertions near the terminus of DNA replication.
Meningococcal Transferrin-Binding Proteins A and B Show Cooperation in Their Binding Kinetics for Human Transferrin
Authors: Stokes Russell H. , Oakhill Jonathan S. , Joannou Christopher L. , Gorringe Andrew R. , Evans Robert W. 
Published: January 2005

ABSTRACT

Neisseria meningitidis
, a causative agent of bacterial meningitis and septicemia, obtains transferrin-bound iron by expressing two outer membrane-located transferrin-binding proteins, TbpA and TbpB. A novel system was developed to investigate the interaction between Tbps and human transferrin. Copurified TbpA-TbpB, recombined TbpA-TbpB, and individual TbpA and TbpB were reconstituted into liposomes and fused onto an HPA chip (BIAcore). All preparations formed stable monolayers, which, with the exception of TbpB, could be regenerated by removing bound transferrin. The ligand binding properties of these monolayers were characterized with surface plasmon resonance and shown to be specific for human transferrin. Kinetic data for diferric human transferrin binding showed that recombined TbpA-TbpB had

K
a

and

K
d

values similar to those of copurified TbpA-TbpB. Individual TbpA and TbpB also displayed

K
a

values similar to those of copurified TbpA-TbpB, but their

K
d

values were one order of magnitude higher. Chemical cross-linking studies revealed that TbpA and TbpB, in the absence of human transferrin, formed large complexes with TbpA as the predominant species. Upon human transferrin binding, a complex was formed with a molecular mass corresponding to that of a TbpB-human transferrin heterodimer as well as a higher-molecular-mass complex of this heterodimer cross-linked to TbpA. This indicates that TbpA and TbpB form a functional meningococcal receptor complex in which there is cooperativity in the human transferrin binding kinetics. However, iron loss from the diferric human transferrin-TbpA-TbpB complex was not greater than that from human transferrin alone, suggesting that additional meningococcal transport components are involved in the process of iron removal.
Protective Levels of Polysaccharide-Specific Maternal Antibodies May Enhance the Immune Response Elicited by Pneumococcal Conjugates in Neonatal and Infant Mice
Authors: Richter Margret Y. , Jakobsen Havard , Haeuw Jean-François , Power Ultan F. , Jonsdottir Ingileif 
Published: January 2005

ABSTRACTMaternal antibodies (MatAbs) may protect the offspring against infections but may also interfere with their immune responses to vaccination. We have previously shown that maternal immunization with pneumococcal polysaccharides (PPS) conjugated to tetanus protein (Pnc-TT) protected the offspring against infections caused by three important pediatric serotypes. To study the influence of MatAb on the immune response to Pnc-TT early in life, adult female mice were immunized twice with Pnc-TT of serotype 1 (Pnc1-TT), and their offspring received Pnc1-TT subcutaneously three times at 3-week intervals starting at 1 week (neonatal) or 3 weeks (infant) of age. High levels of PPS-1-specific MatAb (>3 log) in offspring of Pnc1-TT-immunized dams completely inhibited their anti-PPS-1 response elicited by Pnc1-TT. In contrast, low or moderate (∼1 to 2 log) levels of MatAb did not interfere with and even enhanced the immune response of the offspring, and a booster response to a second Pnc1-TT dose was observed. Carrier-specific MatAbs had little effect on the response of offspring to the conjugate. All Pnc1-TT-immunized offspring were protected against pneumococcal bacteremia and had reduced lung infection. These results demonstrate that in the presence of MatAb, Pnc1-TT may elicit a protective PPS-1-specific antibody response and prime for PPS-1-specific memory in young offspring. Importantly, low or moderate levels of PPS-1-specific MatAb not only provided protection against pneumococcal infections but also enhanced the immune response elicited by Pnc1-TT in neonatal and infant mice. This murine model will be used to develop novel strategies combining maternal and neonatal immunization to protect against infections caused by encapsulated bacteria in early life.
Second-Generation Recombination-Based In Vivo Expression Technology for Large-Scale Screening for
Vibrio cholerae
Genes Induced during Infection of the Mouse Small Intestine
Authors: Osorio C. G. , Crawford J. A. , Michalski J. , Martinez-Wilson H. , Kaper J. B. , Camilli A. 
Published: January 2005

ABSTRACT

We have constructed an improved recombination-based in vivo expression technology (RIVET) and used it as a screening method to identify
Vibrio cholerae
genes that are transcriptionally induced during infection of infant mice. The improvements include the introduction of modified substrate cassettes for resolvase that can be positively and negatively selected for, allowing selection of resolved strains from intestinal homogenates, and three different
tnpR
alleles that cover a range of translation initiation efficiencies, allowing identification of infection-induced genes that have low-to-moderate basal levels of transcription during growth in vitro. A transcriptional fusion library of 8,734 isolates of a
V. cholerae
El Tor strain that remain unresolved when the vibrios are grown in vitro was passed through infant mice, and 40 infection-induced genes were identified. Nine of these genes were inactivated by in-frame deletions, and their roles in growth in vitro and fitness during infection were measured by competition assays. Four mutant strains were attenuated >10-fold in vivo compared with the parental strain, demonstrating that infection-induced genes are enriched in genes essential for virulence.
Role of σ
B
in the Expression of
Staphylococcus aureus
Cell Wall Adhesins ClfA and FnbA and Contribution to Infectivity in a Rat Model of Experimental Endocarditis
Authors: Entenza Jose-Manuel , Moreillon Philippe , Senn Maria Magdalena , Kormanec Jan , Dunman Paul M. , Berger-Bächi Brigitte , Projan Steven , Bischoff Markus 
Published: January 2005

ABSTRACT

Isogenic
Staphylococcus aureus
strains with different capacities to produce σ
B
activity were analyzed for their ability to attach to fibrinogen- or fibronectin-coated surfaces or platelet-fibrin clots and to cause endocarditis in rats. In comparison to the σ
B
-deficient strain, BB255, which harbors an
rsbU
mutation, both
rsbU
-complemented and σ
B
-overproducing derivatives exhibited at least five times greater attachment to fibrinogen- and fibronectin-coated surfaces and showed increased adherence to platelet-fibrin clots. No differences in adherence were seen between BB255 and a Δ
rsbUVWsigB
isogen. Northern blotting analyses revealed that transcription of
clfA
, encoding fibrinogen-binding protein clumping factor A, and
fnbA
, encoding fibronectin-binding protein A, were positively influenced by σ
B
. σ
B
overproduction resulted in a statistically significant increase in positive spleen cultures and enhanced bacterial densities in both the aortic vegetations and spleens at 16 h postinoculation. In contrast, at 72 h postinoculation, tissues infected with the σ
B
overproducer had lower bacterial densities than did those infected with BB255. These results suggest that although σ
B
appears to increase the adhesion of
S. aureus
to various host cell-matrix proteins in vitro, it has limited effect on pathogenesis in the rat endocarditis model. σ
B
appears to have a transient enhancing effect on bacterial density in the early stages of infection that is lost during progression.
Vaccination with Recombinant N-Terminal Domain of Als1p Improves Survival during Murine Disseminated Candidiasis by Enhancing Cell-Mediated, Not Humoral, Immunity
Authors: Ibrahim Ashraf S. , Spellberg Brad J. , Avenissian Valentina , Fu Yue , Filler Scott G. , Edwards John E. 
Published: January 2005

ABSTRACTCandidaspp. are opportunistic fungal pathogens that are among the most common causes of nosocomial bloodstream infections. The mortality attributable to disseminated candidiasis is 40 to 50% despite antifungal therapy. Clearly, new strategies are needed to prevent this life-threatening infection. Because risk factors for disseminated candidiasis are well defined and frequently of limited duration, vaccination is an appealing prophylactic strategy. We have identified a cell surface protein, Als1p, that mediates adherence ofCandida albicansto a variety of human substrates and plastic. Here we report that immunizing BALB/c mice with the recombinant N-terminal domain of Als1p (rAls1p-N) improved survival during a subsequent challenge with a lethal inoculum ofC. albicans. The protective 20-μg dose of rAls1p-N significantly increasedCandidastimulation of Th1 splenocytes and increased in vivo delayed-type hypersensitivity. In contrast, antibody titers did not correlate with protection. Finally, the vaccine was not protective in T-cell-deficient mice but was protective in B-cell-deficient mice. These data indicate that the mechanism of action of the rAls1p-N vaccine is stimulation of cell-mediated, rather than humoral, immunity againstC. albicans. The majority of efforts to date have focused on the development of passive immunization strategies to prevent or treat disseminated candidiasis. In contrast, our results provide proof of principle for vaccination with an adhesin ofC. albicansand emphasize the potential for cell-mediated immune modulation as a prophylactic or therapeutic strategy against disseminated candidiasis.
Cost effectiveness of adding magnetic resonance imaging to the usual management of suspected scaphoid fractures
Authors: Brooks S , Cicuttini F M , Lim S , Taylor D , Stuckey S L , Wluka A E 
Published: January 2005

Objective:To determine the cost effectiveness of a magnetic resonance imaging scan (MRI) within 5 days of injury compared with the usual management of occult scaphoid fracture.Methods:All patients with suspected scaphoid fractures in five hospitals were invited to participate in a randomised controlled trial of usual treatment with or without an MRI scan. Healthcare costs were compared, and a cost effectiveness analysis of the use of MRI in this scenario was performed.Results:Twenty eight of the 37 patients identified were randomised: 17 in the control group, 11 in the MRI group. The groups were similar at baseline and follow up in terms of number of scaphoid fractures, other injuries, pain, and function. Of the patients without fracture, the MRI group had significantly fewer days immobilised: a median of 3.0 (interquartile range 3.0–3.0)v10.0 (7–12) in the control group (p  =  0.006). The MRI group used fewer healthcare units (median 3.0, interquartile range 2.0–4.25) than the control group (5.0, 3.0–6.5) (p  =  0.03 for the difference). However, the median cost of health care in the MRI group ($594.35 AUD, $551.35–667.23) was slightly higher than in the control group ($428.15, $124.40–702.65) (p  =  0.19 for the difference). The mean incremental cost effectiveness ratio derived from this simulation was that MRI costs $44.37 per day saved from unnecessary immobilisation (95% confidence interval $4.29 to $101.02). An illustrative willingness to pay was calculated using a combination of the trials measure of the subjects’ individual productivity losses and the average daily earnings.Conclusions:Use of MRI in the management of occult scaphoid fracture reduces the number of days of unnecessary immobilisation and use of healthcare units. Healthcare costs increased non-significantly in relation to the use of MRI in this setting. However, when productivity losses are considered, MRI may be considered cost effective, depending on the individual case.
Effect of dry needling of gluteal muscles on straight leg raise: a randomised, placebo controlled, double blind trial
Authors: Huguenin L , Brukner P D , McCrory P , Smith P , Wajswelner H , Bennell K 
Published: January 2005

Objectives:To use a randomised, double blind, placebo controlled trial to establish the effect on straight leg raise, hip internal rotation, and muscle pain of dry needling treatment to the gluteal muscles in athletes with posterior thigh pain referred from gluteal trigger points.Methods:A randomised, double blind, placebo controlled trial of 59 male runners was performed during the 2002 Australian Rules football season. Subjects were thoroughly screened and had magnetic resonance imaging of their hamstring muscles to exclude local pathology. The inclusion criterion was reproduction of recognisable posterior thigh pain with the application of digital pressure to the gluteal trigger points. Subjects randomly received either therapeutic or placebo needle treatment on one occasion at their gluteal trigger points. Range of motion and visual analogue scale data were collected immediately before, immediately after, 24 hours after, and 72 hours after the intervention. Range of motion was measured with passive straight leg raise and hip internal rotation. Visual analogue scales were completed for hamstring and gluteal pain and tightness at rest and during a running task.Results:Magnetic resonance imaging scans revealed normal hamstring musculature in most subjects. Straight leg raise and hip internal rotation remained unchanged in both groups at all times. Visual analogue scale assessment of hamstring pain and tightness and gluteal tightness after running showed improvements immediately after the intervention in both groups (p  =  0.001), which were maintained at 24 and 72 hours. The magnitude of this improvement was the same for therapeutic and placebo interventions. Resting muscle pain and tightness were unaffected.Conclusions:Neither dry needling nor placebo needling of the gluteal muscles resulted in any change in straight leg raise or hip internal rotation. Both interventions resulted in subjective improvement in activity related muscle pain and tightness. Despite being commonly used clinical tests in this situation, straight leg raise and hip internal rotation are not likely to help the therapist assess response to treatment. Patient reports of response to such treatment are better indicators of its success. The mechanisms by which these responses occur and the reasons for the success of the placebo needling treatment are areas for further investigation.
Effects of training period on haemorheological variables in regularly trained footballers
Authors: Karakoc Y , Duzova H , Polat A , Emre M H , Arabaci I 
Published: January 2005

Objective:To investigate the effects of one football training period on haemorheological variables in regularly trained footballers.Method:Ten subjects were randomly selected from the reserve team of a football club in the Turkish Premier League. During the last week of the football season, one day before a standard training session and two days after the previous league match, venous blood samples were taken (pre-exercise). After 90 minutes of standard training, further blood samples were taken (post-exercise). Blood lactate, blood viscosity, plasma fibrinogen, blood clotting time, acid-base variables, and plasma Na+, K+, and Ca2+were determined.Results:Haemoglobin, packed cell volume, and mean corpuscular volume were all significantly decreased, whereas white blood cells and platelets were both increased after training. Blood viscosity decreased but the reduction was not significant. Blood lactate, plasma glucose, and Na+content were significantly increased, but standard bicarbonate, actual bicarbonate, and Ca2+were significantly decreased. Blood clotting time had shortened significantly after training. Blood viscosity was inversely correlated with plasma glucose concentration (r =  −0.48 and p  =  0.032).Conclusions:The results show that blood viscosity tends to decrease as the result of this type of training. This is due to a reduction in packed cell volume and mean corpuscular volume. The increased blood lactate does not have an adverse effect on the blood viscosity of these subjects because protective mechanisms develop with regular training throughout the season.
Gender differences in the association of age with physical workload and functioning
Authors: Aittomäki A , Lahelma E , Roos E , Leino-Arjas P , Martikainen P 
Published: January 2005

Aims:To test whether (1) physically demanding work is less frequent for older than younger employees, and whether (2) the association of physically demanding work with decline of physical functioning is stronger for older employees than their younger counterparts. The gender differences in these associations were examined.Methods:Subjects of the study were 40–60 year old employees of the City of Helsinki. Data (n = 5802) were collected with mail questionnaires in 2000 and 2001. Functioning was measured with the Role Limitations due to Physical Health Problems scale of the SF36 health questionnaire. Logistic regression models were used to analyse the data.Results:There was a linear trend of less physically demanding work in older than in younger age groups. This trend was more marked for men than women. Age and physically demanding work were associated with poor functioning. In women the association of physically demanding work with poor functioning tended to be stronger for older than for younger age groups, while the opposite was observed in men.Conclusions:Results suggest that physically demanding work causes more ailments in women of high age than men. It is possible that less men than women are still employed in physically demanding occupations at high age, even though direct evidence of exit from physically demanding work cannot be obtained from cross-sectional data. In these data the physically demanding occupations for men and women were largely different. High physical workload among women working in social and health care is likely to contribute to the gender differences.