bluuebunny/crossref_metadata_2025 huggingface dataset:
Prevalence of Fluoroquinolone Resistance among Tuberculosis Patients in Shanghai, China
Authors: Xu Peng , Li Xia , Zhao Ming , Gui Xiaohong , DeRiemer Kathryn , Gagneux Sebastien , Mei Jian , Gao Qian
Published: April 2009

We determined the prevalence of fluoroquinolone resistance among the isolates of
Mycobacterium tuberculosis
from 605 pulmonary tuberculosis patients in Shanghai, China. Mutations in
gyrA
were found in 81.5% of phenotypically fluoroquinolone-resistant isolates and were used as a molecular marker of fluoroquinolone resistance.
gyrA
mutations were detected in 1.9% of strains pan-susceptible to first-line drugs and 25.1% of multidrug-resistant strains. Fluoroquinolone resistance was independently associated with resistance to at least one first-line drug and prior tuberculosis treatment.
Combination of Daptomycin plus Ceftriaxone Is More Active than Vancomycin plus Ceftriaxone in Experimental Meningitis after Addition of Dexamethasone
Authors: Egermann U. , Stanga Z. , Ramin A. , Acosta F. , Stucki A. , Gerber P. , Cottagnoud M. , Cottagnoud P.
Published: April 2009

We examined the cerebrospinal fluid penetration of daptomycin after the addition of dexamethasone and its bactericidal efficacy with and without ceftriaxone in an experimental rabbit model of pneumococcal meningitis. The combination of daptomycin with ceftriaxone was the most efficacious regimen for pneumococcal meningitis. The previous addition of dexamethasone affected the antibacterial activity of daptomycin only marginally, either as monotherapy or combined with ceftriaxone, although the penetration of daptomycin into inflamed meninges was significantly reduced from 6 to 2%. Daptomycin with ceftriaxone might be a potential candidate for the empirical therapy of bacterial meningitis, although the activity of this regimen against
Listeria monocytogenes
remains to be demonstrated.
Early- and Late-Onset Pneumonia: Is This Still a Useful Classification?
Authors: Gastmeier Petra , Sohr Dorit , Geffers Christine , Rüden Henning , Vonberg Ralf-Peter , Welte Tobias
Published: April 2009

The choice of empirical treatment of nosocomial pneumonia in the intensive-care unit (ICU) used to rely on the interval after the start of mechanical ventilation. Nowadays, however, the question of whether in fact there is a difference in the distribution of causative pathogens is under debate. Data from 308 ICUs from the German National Nosocomial Infection Surveillance System, including information on relevant pathogens isolated in 11,285 cases of nosocomial pneumonia from 1997 to 2004, were used for our evaluation. Each individual pneumonia case was allocated either to early- or to late-onset pneumonia, with three differentiation criteria: onset on the 4th day, the 5th day, or the 7th day in the ICU. The frequency of pathogens was evaluated according to these categories. A total of 5,066 additional cases of pneumonia were reported from 2005 to 2006, after the CDC criteria had been modified. From 1997 to 2004, the most frequent microorganisms were
Staphylococcus aureus
(2,718 cases, including 720 with methicillin [meticillin]-resistant
S. aureus
), followed by
Pseudomonas aeruginosa
(1,837 cases),
Klebsiella pneumoniae
(1,305 cases),
Escherichia coli
(1,137 cases),
Enterobacter
spp. (937 cases), streptococci (671 cases),
Haemophilus influenzae
(509 cases),
Acinetobacter
spp. (493 cases), and
Stenotrophomonas maltophilia
(308 cases). The order of the four most frequent pathogens (accounting for 53.7% of all pathogens) was the same in both groups and was independent of the cutoff categories applied:
S. aureus
was first, followed by
P. aeruginosa
,
K. pneumoniae
, and
E. coli
. Thus, the predictabilities of the occurrence of pathogens were similar for the earlier (1997-to-2004) and later (2005-to-2006) time frames. This classification is no longer helpful for empirical antibiotic therapy, since the pathogens are the same for both groups.
Prevalence and Risk Factors for Aminoglycoside Nephrotoxicity in Intensive Care Units
Authors: Oliveira João F. P. , Silva Carolina A. , Barbieri Camila D. , Oliveira Giselle M. , Zanetta Dirce M. T. , Burdmann Emmanuel A.
Published: April 2009

In order to assess the prevalence of and risk factors for aminoglycoside-associated nephrotoxicity in intensive care units (ICUs), we evaluated 360 consecutive patients starting aminoglycoside therapy in an ICU. The patients had a baseline calculated glomerular filtration rate (cGFR) of ≥30 ml/min/1.73 m2. Among these patients, 209 (58%) developed aminoglycoside-associated nephrotoxicity (the acute kidney injury [AKI] group, which consisted of individuals with a decrease in cGFR of >20% from the baseline cGFR), while 151 did not (non-AKI group). Both groups had similar baseline cGFRs. The AKI group developed a lower cGFR nadir (45 ± 27 versus 79 ± 39 ml/min/1.73 m2for the non-AKI group;P< 0.001); was older (56 ± 18 years versus 52 ± 19 years for the non-AKI group;P= 0.033); had a higher prevalence of diabetes (19.6% versus 9.3% for the non-AKI group;P= 0.007); was more frequently treated with other nephrotoxic drugs (51% versus 38% for the non-AKI group;P= 0.024); used iodinated contrast more frequently (18% versus 8% for the non-AKI group;P= 0.0054); and showed a higher prevalence of hypotension (63% versus 44% for the non-AKI group;P= 0.0003), shock (56% versus 31% for the non-AKI group;P< 0.0001), and jaundice (19% versus 8% for the non-AKI group;P= 0.0036). The mortality rate was 44.5% for the AKI group and 29.1% for the non-AKI group (P= 0.0031). A logistic regression model identified as significant (P< 0.05) the following independent factors that affected aminoglycoside-associated nephrotoxicity: a baseline cGFR of <60 ml/min/1.73 m2(odds ratio [OR], 0.42), diabetes (OR, 2.13), treatment with other nephrotoxins (OR, 1.61) or iodinated contrast (OR, 2.13), and hypotension (OR, 1.83). In conclusion, AKI was frequent among ICU patients receiving an aminoglycoside, and it was associated with a high rate of mortality. The presence of diabetes or hypotension and the use of other nephrotoxic drugs and iodinated contrast were independent risk factors for the development of aminoglycoside-associated nephrotoxicity.
Farnesol-Induced Apoptosis in
Candida albicans
Authors: Shirtliff Mark E. , Krom Bastiaan P. , Meijering Roelien A. M. , Peters Brian M. , Zhu Jingsong , Scheper Mark A. , Harris Megan L. , Jabra-Rizk Mary Ann
Published: April 2009

Farnesol, a precursor in the isoprenoid/sterol pathway, was recently identified as a quorum-sensing molecule produced by the fungal pathogen
Candida albicans
. Farnesol is involved in the inhibition of germination and biofilm formation by
C. albicans
and can be cytotoxic at certain concentrations. In addition, we have shown that farnesol can trigger apoptosis in mammalian cells via the classical apoptotic pathways. In order to elucidate the mechanism behind farnesol cytotoxicity in
C. albicans
, the response to farnesol was investigated, using proteomic analysis. Global protein expression profiles demonstrated significant changes in protein expression resulting from farnesol exposure. Among the downregulated proteins were those involved in metabolism, glycolysis, protein synthesis, and mitochondrial electron transport and the respiratory chain, whereas proteins involved in folding, protection against environmental and oxidative stress, actin cytoskeleton reorganization, and apoptosis were upregulated. Cellular changes that accompany apoptosis (regulated cell death) were further analyzed using fluorescent microscopy and gene expression analysis. The results indicated reactive oxygen species accumulation, mitochondrial degradation, and positive terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL) in the farnesol-exposed cells concurrent with increased expression of antioxidant-encoding and drug response genes. More importantly, the results demonstrated farnesol-induced upregulation of the caspase gene
MCA1
and the intracellular presence of activated caspases. In conclusion, this study demonstrated that farnesol promotes apoptosis in
C. albicans
through caspase activation, implying an important physiological role for farnesol in the fungal cell life cycle with important implications for adaptation and survival.
Antibacterial Efficacy of Phages against
Pseudomonas aeruginosa
Infections in Mice and
Drosophila melanogaster
Authors: Heo Yun-Jeong , Lee Yu-Rim , Jung Hyun-Hee , Lee JungEun , Ko GwangPyo , Cho You-Hee
Published: April 2009

Phage therapy against
Pseudomonas aeruginosa
infections has received renewed attention owing to the increasing prevalence of antibiotic resistance in this bacterium. Here, we isolated and characterized two new potentially lytic bacteriophages (MPK1 and MPK6), which produced large and clear plaques on
P. aeruginosa
strain PAO1. Based on their morphology, MPK1 belongs to the
Myoviridae
, while MPK6 belongs to the
Podoviridae
. The group B polysaccharide of lipopolysaccharide was required for infection, suggesting that their host spectra are associated with the serotypes of
P. aeruginosa
strains. Intramuscular and intraperitoneal administration of MPK1 and, to a lesser extent, MPK6 significantly protected mice from mortality caused by PAO1-induced peritonitis-sepsis (
P
< 0.01). Mice treated with either phage also had lower bacterial burdens in their livers, lungs, and spleens. The antibacterial efficacy of MPK1 and MPK6 was also evaluated based on
Drosophila melanogaster
systemic infection caused by
P. aeruginosa
, for which phages were administered by feeding. Both phages significantly delayed the PAO1-induced killing of
D. melanogaster
(
P
< 0.001), although MPK1 persisted longer than MPK6 in uninfected
D. melanogaster
tissue samples. These results suggest that a mini-scale experiment using
D. melanogaster
infection is valid for evaluating the antibacterial efficacy of phage therapy against
P. aeruginosa
infections.
In Vivo Pharmacodynamic Profile of Tigecycline against Phenotypically Diverse
Escherichia coli
and
Klebsiella pneumoniae
Isolates
Authors: Nicasio Anthony M. , Crandon Jared L. , Nicolau David P.
Published: April 2009

Tigecycline is a glycylcycline with activity against
Enterobacteriaceae
, including multidrug-resistant isolates of
Klebsiella pneumoniae
and
Escherichia coli
producing extended-spectrum beta-lactamase (ESBL) and carbapenemases. Herein, we used an in vivo murine thigh model to characterize the pharmacodynamic profile of tigecycline against genotypically and phenotypically diverse
K. pneumoniae
and
E. coli
isolates. Doses of 3.125 to 300 mg/kg, divided 1 to 6 times daily, were administered subcutaneously against six (two nonresistant, one carbapenemase, and three ESBL producing)
K. pneumoniae
strains and five (two nonresistant and three ESBL producing)
E. coli
strains. The phenotypic profile (reported tigecycline MIC) for all isolates ranged from 0.125 to 2 μg/ml. Mean correlation coefficients of free (
f
) drug exposures (percentage of the dosing interval that free drug concentration remained above the MIC [
fT
>MIC], the ratio of the free drug area under the concentration-time curve/MIC [
f
AUC/MIC], and the ratio of maximum concentration of free drug in serum/MIC) for all 11 isolates were 0.595, 0.969, and 0.897, respectively. The
f
AUC/MIC was the pharmacodynamic parameter that best described the efficacy of tigecycline against both
E. coli
and
K. pneumoniae
. Interestingly, reductions in the number of CFU were noted even though doses achieved an
fT
>MIC of 0%. With respect to
f
AUC/MIC in the neutropenic model, the cumulative 80% and 50% effective pharmacodynamic indexes (EI
80
and EI
50
) for all 11 isolates were 8.4 and 4.7, respectively. An experiment in nonneutropenic mice infected with an ESBL-producing
E. coli
and
K. pneumoniae
isolate resulted in the lowest tigecycline
f
AUC/MIC EI
80
and EI
50
values at 1.8 and 1.0 for
E. coli
and 1.7 and 1.6 for
K. pneumoniae
. While the phenotypic profile of tigecycline appeared to drive efficacy irrespective of ESBL or carbapenemase production, the presence of a competent immune system markedly reduced this required exposure.
Dermcidin-Derived Peptides Show a Different Mode of Action than the Cathelicidin LL-37 against
Staphylococcus aureus
Authors: Senyürek Ilknur , Paulmann Maren , Sinnberg Tobias , Kalbacher Hubert , Deeg Martin , Gutsmann Thomas , Hermes Marina , Kohler Thomas , Götz Fritz , Wolz Christiane , Peschel Andreas , Schittek Birgit
Published: April 2009

Dermcidin (DCD) is an antimicrobial peptide which is constitutively expressed in eccrine sweat glands. By postsecretory proteolytic processing in sweat, the DCD protein gives rise to anionic and cationic DCD peptides with a broad spectrum of antimicrobial activity. Many antimicrobial peptides induce membrane permeabilization as part of their killing mechanism, which is accompanied by a loss of the bacterial membrane potential. In this study we show that there is a time-dependent bactericidal activity of anionic and cationic DCD-derived peptides which is followed by bacterial membrane depolarization. However, DCD-derived peptides do not induce pore formation in the membranes of gram-negative and gram-positive bacteria. This is in contrast to the mode of action of the cathelicidin LL-37. Interestingly, LL-37 as well as DCD-derived peptides inhibit bacterial macromolecular synthesis, especially RNA and protein synthesis, without binding to microbial DNA or RNA. Binding studies with components of the cell envelope of gram-positive and gram-negative bacteria and with model membranes indicated that DCD-derived peptides bind to the bacterial envelope but show only a weak binding to lipopolysaccharide (LPS) from gram-negative bacteria or to peptidoglycan, lipoteichoic acid, and wall teichoic acid, isolated from
Staphylococcus aureus
. In contrast, LL-37 binds strongly in a dose-dependent fashion to these components. Altogether, these data indicate that the mode of action of DCD-derived peptides is different from that of the cathelicidin LL-37 and that components of the bacterial cell envelope play a role in the antimicrobial activity of DCD.
Infectious Complications Associated with Monoclonal Antibodies and Related Small Molecules
Authors: Salvana Edsel Maurice T. , Salata Robert A.
Published: April 2009

Biologics are increasingly becoming part of routine disease management. As more agents are developed, the challenge of keeping track of indications and side effects is growing. While biologics represent a milestone in targeted and specific therapy, they are not without drawbacks, and the judicious use of these “magic bullets” is essential if their full potential is to be realized. Infectious complications in particular are not an uncommon side effect of therapy, whether as a direct consequence of the agent or because of the underlying disease process. With this in mind, we have reviewed and summarized the risks of infection and the infectious disease-related complications for all FDA-approved monoclonal antibodies and some related small molecules, and we discuss the probable mechanisms involved in immunosuppression as well as recommendations for prophylaxis and treatment of specific disease entities.
Gastric Helicobacters in Domestic Animals and Nonhuman Primates and Their Significance for Human Health
Authors: Haesebrouck Freddy , Pasmans Frank , Flahou Bram , Chiers Koen , Baele Margo , Meyns Tom , Decostere Annemie , Ducatelle Richard
Published: April 2009

Helicobacters other thanHelicobacter pylorihave been associated with gastritis, gastric ulcers, and gastric mucosa-associated lymphoid tissue lymphoma in humans. These very fastidious microorganisms with a typical large spiral-shaped morphology were provisionally designated “H. heilmannii,” but in fact they comprise at least five differentHelicobacterspecies, all of which are known to colonize the gastric mucosa of animals.H. suis, which has been isolated from the stomachs of pigs, is the most prevalent gastric non-H. pylori Helicobacterspecies in humans. Other gastric non-H. pylorihelicobacters colonizing the human stomach areH. felis, H. salomonis, H. bizzozeronii, and the still-uncultivable “CandidatusHelicobacter heilmannii.” These microorganisms are often detected in the stomachs of dogs and cats. “CandidatusHelicobacter bovis” is highly prevalent in the abomasums of cattle but has only occasionally been detected in the stomachs of humans. There are clear indications that gastric non-H. pylori Helicobacterinfections in humans originate from animals, and it is likely that transmission to humans occurs through direct contact. Little is known about the virulence factors of these microorganisms. The recent successes with in vitro isolation of non-H. pylorihelicobacters from domestic animals open new perspectives for studying these microorganisms and their interactions with the host.
Update on Eosinophilic Meningoencephalitis and Its Clinical Relevance
Authors: Graeff-Teixeira Carlos , da Silva Ana Cristina Arámburu , Yoshimura Kentaro
Published: April 2009

Eosinophilic meningoencephalitis is caused by a variety of helminthic infections. These worm-specific infections are named after the causative worm genera, the most common being angiostrongyliasis, gnathostomiasis, toxocariasis, cysticercosis, schistosomiasis, baylisascariasis, and paragonimiasis. Worm parasites enter an organism through ingestion of contaminated water or an intermediate host and can eventually affect the central nervous system (CNS). These infections are potentially serious events leading to sequelae or death, and diagnosis depends on currently limited molecular methods. Identification of parasites in fluids and tissues is rarely possible, while images and clinical examinations do not lead to a definitive diagnosis. Treatment usually requires the concomitant administration of corticoids and anthelminthic drugs, yet new compounds and their extensive and detailed clinical evaluation are much needed. Eosinophilia in fluids may be detected in other infectious and noninfectious conditions, such as neoplastic disease, drug use, and prosthesis reactions. Thus, distinctive identification of eosinophils in fluids is a necessary component in the etiologic diagnosis of CNS infections.
Pathogen Recognition and Inflammatory Signaling in Innate Immune Defenses
Authors: Mogensen Trine H.
Published: April 2009

The innate immune system constitutes the first line of defense against invading microbial pathogens and relies on a large family of pattern recognition receptors (PRRs), which detect distinct evolutionarily conserved structures on pathogens, termed pathogen-associated molecular patterns (PAMPs). Among the PRRs, the Toll-like receptors have been studied most extensively. Upon PAMP engagement, PRRs trigger intracellular signaling cascades ultimately culminating in the expression of a variety of proinflammatory molecules, which together orchestrate the early host response to infection, and also is a prerequisite for the subsequent activation and shaping of adaptive immunity. In order to avoid immunopathology, this system is tightly regulated by a number of endogenous molecules that limit the magnitude and duration of the inflammatory response. Moreover, pathogenic microbes have developed sophisticated molecular strategies to subvert host defenses by interfering with molecules involved in inflammatory signaling. This review presents current knowledge on pathogen recognition through different families of PRRs and the increasingly complex signaling pathways responsible for activation of an inflammatory and antimicrobial response. Moreover, medical implications are discussed, including the role of PRRs in primary immunodeficiencies and in the pathogenesis of infectious and autoimmune diseases, as well as the possibilities for translation into clinical and therapeutic applications.
EnterotoxigenicBacteroides fragilis: a Rogue among Symbiotes
Authors: Sears Cynthia L.
Published: April 2009

EnterotoxigenicBacteroides fragilis(ETBF) strains are strains ofB. fragilisthat secrete a 20-kDa heat-labile zinc-dependent metalloprotease toxin termed theB. fragilistoxin (BFT). BFT is the only recognized virulence factor specific for ETBF. ETBF strains are associated with inflammatory diarrheal disease in children older than 1 year of age and in adults; limited data suggest an association of ETBF colonization with inflammatory bowel disease flare-ups and colorectal cancer. ETBF secretes one of three highly related BFT isoforms. The relationship between BFT isoform and disease expression is unknown. Although the mechanism of action of BFT is incompletely understood, available data suggest that BFT binds to a specific intestinal epithelial cell receptor, stimulating intestinal cell signal transduction pathways that result in cell morphology changes, cleavage of E-cadherin, reduced colonic barrier function, and increased epithelial cell proliferation and cytokine expression (such as the proinflammatory chemokine interleukin-8). Together, the data suggest that in some hosts, ETBF acts via secretion of BFT to induce colitis. However, the full spectrum of clinical disease related to ETBF and the impact of chronic ETBF colonization on the host remain to be defined.
Identification of a Novel Lipopolysaccharide Core Biosynthesis Gene Cluster in
Bordetella pertussis
, and Influence of Core Structure and Lipid A Glucosamine Substitution on Endotoxic Activity
Authors: Geurtsen Jeroen , Dzieciatkowska Monika , Steeghs Liana , Hamstra Hendrik-Jan , Boleij Johanna , Broen Kelly , Akkerman Grietsje , el Hassan Hassan , Li Jianjun , Richards James C. , Tommassen Jan , van der Ley Peter
Published: April 2009

Lipopolysaccharide (LPS), also known as endotoxin, is one of the main constituents of the gram-negative bacterial outer membrane. Whereas the lipid A portion of LPS is generally considered the main determinant for endotoxic activity, the oligosaccharide moiety plays an important role in immune evasion and the interaction with professional antigen-presenting cells. Here we describe a novel four-gene cluster involved in the biosynthesis of the
Bordetella pertussis
core oligosaccharide. By insertionally inactivating these genes and studying the resulting LPS structures, we show that at least two of the genes encode active glycosyltransferases, while a third gene encodes a deacetylase also required for biosynthesis of full-length oligosaccharide. In addition, we demonstrate that mutations in the locus differentially affect LPS and whole-cell endotoxic activities. Furthermore, while analyzing the mutant LPS structures, we confirmed a novel modification of the lipid A phosphate with glucosamine and found that inactivation of the responsible glycosyltransferase reduces the endotoxic activity of the LPS.
Salmonella enterica
Serovar Enteritidis Pathogenicity Island 1 Is Not Essential for but Facilitates Rapid Systemic Spread in Chickens
Authors: Desin Taseen S. , Lam Po-King S. , Koch Birgit , Mickael Claudia , Berberov Emil , Wisner Amanda L. S. , Townsend Hugh G. G. , Potter Andrew A. , Köster Wolfgang
Published: April 2009

Salmonella enterica
subsp.
enterica
serovar Enteritidis is a leading cause of human food-borne illness that is mainly associated with the consumption of contaminated poultry meat and eggs. To cause infection,
S.
Enteritidis is known to use two type III secretion systems, which are encoded on two salmonella pathogenicity islands, SPI-1 and SPI-2, the first of which is thought to play a major role in invasion and bacterial uptake. In order to study the role of SPI-1 in the colonization of chicken, we constructed deletion mutants affecting the complete SPI-1 region (40 kb) and the
invG
gene. Both ΔSPI-1 and Δ
invG
mutant strains were impaired in the secretion of SipD, a SPI-1 effector protein. In vitro analysis using polarized human intestinal epithelial cells (Caco-2) revealed that both mutant strains were less invasive than the wild-type strain. A similar observation was made when chicken cecal and small intestinal explants were coinfected with the wild-type and ΔSPI-1 mutant strains. Oral challenge of 1-week-old chicken with the wild-type or ΔSPI-1 strains demonstrated that there was no difference in chicken cecal colonization. However, systemic infection of the liver and spleen was delayed in birds that were challenged with the ΔSPI-1 strain. These data demonstrate that SPI-1 facilitates systemic infection but is not essential for invasion and systemic spread of the organism in chickens.
Precolonized Human Commensal
Escherichia coli
Strains Serve as a Barrier to
E. coli
O157:H7 Growth in the Streptomycin-Treated Mouse Intestine
Authors: Leatham Mary P. , Banerjee Swati , Autieri Steven M. , Mercado-Lubo Regino , Conway Tyrrell , Cohen Paul S.
Published: April 2009

Different
Escherichia coli
strains generally have the same metabolic capacity for growth on sugars in vitro, but they appear to use different sugars in the streptomycin-treated mouse intestine (Fabich et al., Infect. Immun. 76:1143-1152, 2008). Here, mice were precolonized with any of three human commensal strains (
E. coli
MG1655,
E. coli
HS, or
E. coli
Nissle 1917) and 10 days later were fed 10
5
CFU of the same strains. While each precolonized strain nearly eliminated its isogenic strain, confirming that colonization resistance can be modeled in mice, each allowed growth of the other commensal strains to higher numbers, consistent with different commensal
E. coli
strains using different nutrients in the intestine. Mice were also precolonized with any of five commensal
E. coli
strains for 10 days and then were fed 10
5
CFU of
E. coli
EDL933, an O157:H7 pathogen.
E. coli
Nissle 1917 and
E. coli
EFC1 limited growth of
E. coli
EDL933 in the intestine (10
3
to 10
4
CFU/gram of feces), whereas
E. coli
MG1655,
E. coli
HS, and
E. coli
EFC2 allowed growth to higher numbers (10
6
to 10
7
CFU/gram of feces). Importantly, when
E. coli
EDL933 was fed to mice previously co-colonized with three
E. coli
strains (MG1655, HS, and Nissle 1917), it was eliminated from the intestine (<10 CFU/gram of feces). These results confirm that commensal
E. coli
strains can provide a barrier to infection and suggest that it may be possible to construct
E. coli
probiotic strains that prevent growth of pathogenic
E. coli
strains in the intestine.
Salmonella enterica
Serovar Typhimurium Pathogenicity Island 1-Encoded Type III Secretion System Translocases Mediate Intimate Attachment to Nonphagocytic Cells
Authors: Lara-Tejero María , Galán Jorge E.
Published: April 2009

Delivery of bacterial proteins into mammalian cells by type III secretion systems (TTSS) is thought to require the intimate association of bacteria with target cells. The molecular bases of this intimate association appear to be different in different bacteria involving TTSS components, as well as surface determinants not associated with TTSS. We show here that the protein translocases SipB, SipC, and SipD of the
Salmonella enterica
serovar Typhimurium pathogenicity island 1 (SPI-1)-encoded TTSS are required for the intimate association of these bacteria with mammalian cells.
S
. Typhimurium mutant strains lacking any of the translocases were defective for intimate attachment. Immunofluorescence microscopy showed that SipD is present on the bacterial surface prior to bacterial contact with host cells. In contrast, SipB and SipC were detected on the bacterial surface only subsequent to bacterial contact with the target cell. We conclude that the coordinated deployment and interaction between the protein translocases mediate the SPI-1 TTSS-dependent intimate association of
S
. Typhimurium with host cells.
Distinct Roles for MyD88 and Toll-Like Receptor 2 during
Leishmania braziliensis
Infection in Mice
Authors: Vargas-Inchaustegui Diego A. , Tai Wendy , Xin Lijun , Hogg Alison E. , Corry David B. , Soong Lynn
Published: April 2009

We have previously reported that
Leishmania braziliensis
infection can activate murine dendritic cells (DCs) and upregulate signaling pathways that are essential for the initiation of innate immunity. However, it remains unclear whether Toll-like receptors (TLRs) are involved in
L. braziliensis
-mediated DC activation. To address this issue, we generated bone marrow-derived DCs from MyD88
−/−
and TLR2
−/−
mice and examined their responsiveness to parasite infection. While wild-type DCs were efficiently activated to produce cytokines and prime naïve CD4
+
T cells,
L. braziliensis
-infected MyD88
−/−
DCs exhibited less activation and decreased production of interleukin-12 (IL-12) p40. Furthermore, MyD88
−/−
mice were more susceptible to infection in that they developed larger and prolonged lesions compared to those in control mice. In sharp contrast, the lack of TLR2 resulted in an enhanced DC activation and increased IL-12 p40 production after infection. As such,
L. braziliensis
-infected TLR2
−/−
DCs were more competent in priming naïve CD4
+
T cells in vitro than were their controls, findings which correlated with an increased gamma interferon production in vivo and enhanced resistance to infection. Our results suggest that while MyD88 is indispensable for the generation of protective immunity to
L. braziliensis
, TLR2 seems to have a regulatory role during infection.
Proteomics-Based Identification of Anchorless Cell Wall Proteins as Vaccine Candidates againstStaphylococcus aureus
Authors: Glowalla Eva , Tosetti Bettina , Krönke Martin , Krut Oleg
Published: April 2009

Staphylococcus aureusis an important human pathogen with increasing clinical impact due to the extensive spread of antibiotic-resistant strains. Therefore, development of a protective polyvalent vaccine is of great clinical interest. We employed an intravenous immunoglobulin (IVIG) preparation as a source of antibodies directed against anchorlessS. aureussurface proteins for identification of novel vaccine candidates. In order to identify such proteins, subtractive proteome analysis (SUPRA) ofS. aureusanchorless cell wall proteins was performed. Proteins reacting with IVIG but not with IVIG depleted ofS. aureus-specific opsonizing antibodies were considered vaccine candidates. Nearly 40 proteins were identified by this preselection method using matrix-assisted laser desorption ionization—time of flight analysis. Three of these candidate proteins, enolase (Eno), oxoacyl reductase (Oxo), and hypothetical protein hp2160, were expressed as glutathioneS-transferase fusion proteins, purified, and used for enrichment of corresponding immunoglobulin Gs from IVIG by affinity chromatography. Use of affinity-purified anti-Eno, anti-Oxo, and anti-hp2160 antibodies resulted in opsonization, phagocytosis, and killing ofS. aureusby human neutrophils. High specific antibody titers were detected in mice immunized with recombinant antigens. In mice challenged with bioluminescentS. aureus, reduced staphylococcal spread was measured by in vivo imaging. The recovery ofS. aureusCFU from organs of immunized mice was diminished 10- to 100-fold. Finally, mice immunized with hp2160 displayed statistically significant higher survival rates after lethal challenge with clinically relevantS. aureusstrains. Taken together, our data suggest that anchorless cell wall proteins might be promising vaccine candidates and that SUPRA is a valuable tool for their identification.
Natural Antibody Contributes to Host Defense against an AttenuatedBrucella abortus virBMutant
Authors: Rolán Hortensia G. , Xavier Mariana N. , Santos Renato L. , Tsolis Renée M.
Published: April 2009

Brucella abortusis an intracellular pathogen that persists within phagocytic cells of the reticuloendothelial system. To identify in vivo interactions betweenB. abortusand the host that lead to persistent infection, we studied the persistence ofB. abortusand an isogenicvirBmutant deficient in the VirB type IV secretion system (T4SS) in knockout mice. In contrast to control mice, mice lacking B cells (Igh6−/−) were permissive for infection with the attenuatedvirBmutant. To determine the basis for this phenotype, we characterized immune functions ofIgh6−/−mice in the context ofB. abortusinfection.Igh6−/−mice had greater numbers of extracellular bacteria in the spleen and increased early expression of proinflammatory cytokines duringB. abortusinfection. Further, avirBmutant, despite its wild-type level of survival, failed to elicit microgranuloma formation in the spleens ofIgh6−/−mice, suggesting a requirement for the T4SS to elicit this pathological change. Passive transfer of immunoglobulin G from naïve mice restored the ability ofIgh6−/−mice to control the persistence of thevirBmutant by a complement-independent mechanism. Further, adoptive transfer of CD11b+cells from C57BL/6 mice toIgh6−/−mice restored the ability of the knockout mice to limit the replication of thevirBmutant in the spleen, suggesting that theIgh6−/−mutation affects phagocyte function and that phagocyte function can be restored by natural antibody.
Role for Endosomal and Vacuolar GTPases in
Candida albicans
Pathogenesis
Authors: Johnston Douglas A. , Eberle Karen E. , Sturtevant Joy E. , Palmer Glen E.
Published: April 2009

The vacuole has crucial roles in stress resistance and adaptation of the fungal cell. Furthermore, in
Candida albicans
it has been observed to undergo dramatic expansion during the initiation of hyphal growth, to produce highly “vacuolated” subapical compartments. We hypothesized that these functions may be crucial for survival within the host and tissue-invasive hyphal growth. We also considered the role of the late endosome or prevacuole compartment (PVC), a distinct organelle involved in vacuolar and endocytic trafficking. We identified two Rab GTPases, encoded by
VPS21
and
YPT72
, required for trafficking through the PVC and vacuole biogenesis, respectively. Deletion of
VPS21
or
YPT72
led to mild sensitivities to some cellular stresses. However, deletion of both genes resulted in a synthetic phenotype with severe sensitivity to cellular stress and impaired growth. Both the
vps21
Δ and
ypt72
Δ mutants had defects in filamentous growth, while the double mutant was completely deficient in polarized growth. The defects in hyphal growth were not suppressed by an “active”
RIM101
allele or loss of the hyphal repressor encoded by
TUP1
. In addition, both single mutants had significant attenuation in a mouse model of hematogenously disseminated candidiasis, while the double mutant was rapidly cleared. Histological examination confirmed that the
vps21
Δ and
ypt72
Δ mutants are deficient in hyphal growth in vivo. We suggest that the PVC and vacuole are required on two levels during
C. albicans
infection: (i) stress resistance functions required for survival within tissue and (ii) a role in filamentous growth which may aid host tissue invasion.
Rotator cuff tendinopathy: a model for the continuum of pathology and related management
Authors: Lewis Jeremy S
Published: April 2009

Background

Pathology of the soft tissues of the shoulder including the musculotendinous rotator cuff and subacromial bursa are extremely common and are a principal cause of pain and suffering. Competing theories have been proposed to explain the pathoaetiology of rotator cuff pathology at specific stages and presentations of the condition. This review proposes a model to describe the continuum of the rotator cuff pathology from asymptomatic tendon through full thickness rotator cuff tears.

Conclusions

The pathoaetiology of rotator cuff failure is multifactorial and results from a combination of intrinsic, extrinsic and environmental factors. Recently a new and generic model detailing the continuum of tendon pathology has been proposed. This model is relevant for the rotator cuff and provides a framework to stage the continuity of rotator cuff pathology. Furthermore, it provides a structure to identify the substantial deficiencies in our knowledge base and areas where research would improve our understanding of the pathological and repair process, together with assessment and management. The strength of this model adapted for the rotator cuff tendons and subacromial bursa will be tested in its ability to incorporate and adapt to emerging research.
Previous experience influences pacing during 20 km time trial cycling
Authors: Micklewright D , Papadopoulou E , Swart J , Noakes T
Published: April 2009

Objective

To investigate how experience and feedback influence pacing and performance during time trial cycling.

Design

Twenty-nine cyclists performed three 20 km cycling time trials using a Computrainer. The first two time trials (TT1 and TT2) were performed (1) without any performance feedback (n = 10), (2) with accurate performance feedback (n = 10) or (3) with false feedback showing the speed to be 5% greater than the actual speed (n = 9). All participants received full feedback during the third time trial (TT3), and their performance and pacing data were compared against TT2.

Results

Completion time, average power and average speed did not change among the false feedback group, but their pacing strategy did change as indicated by a lower average cadence, 89.2 (SD 5.2) vs 96.4 (6.8) rpm, p<0.05, and higher power during the first 5 km (SMD = 39, 36, 36, 27 and 27 W for 1–5 km respectively). Pacing changed among the blind feedback group indicated by a faster completion time, 35.9 (3.1) vs 36.8 (4.4) min, p<0.05, and power increases during the final 5 km (SMD = 14, 13, 18, 23 and 53 W for 16–20 km respectively). No performance or pacing changes were observed among the accurate feedback group.

Conclusions

Pacing is influenced by an interaction between feedback and previous experience. Conscious cognitive processes that lead to ratings of perceived exertion and pacing appear to be influenced by previous experience.
Criterion-related validity of field-based fitness tests in youth: a systematic review
Authors: Castro-Piñero J , Artero E G , España-Romero V , Ortega F B , Sjöström M , Suni J , Ruiz J R
Published: April 2009

The objective of this systematic review was to comprehensively study the criterion-related validity of the existing field-based fitness tests used in children and adolescents. The studies were scored according to the number of subjects, description of the study population and statistical analysis. Each study was classified as high, low and very low quality. Three levels of evidence were constructed: strong evidence, when consistent findings were observed in three or more high quality studies; moderate evidence, when consistent findings were observed in two high quality studies; and limited evidence when consistency of findings and/or the number of studies did not achieve the criteria for moderate. The results of 73 studies (50 of high quality) addressing the criterion-related validity of field-based fitness tests in children and adolescents indicate the following: that there is strong evidence indicating that the 20 m shuttle run test is a valid test to estimate cardiorespiratory fitness, that the hand-grip strength test is a valid measure of musculoskeletal fitness, that skin fold thickness and body mass index are good estimates of body composition, and that waist circumference is a valid measure to estimate central body fat. Moderate evidence was found that the 1-mile run/walk test is a valid test to estimate cardiorespiratory fitness. A large number of other field-based fitness tests presented limited evidence, mainly due to a limited number of studies (one for each test). The results of the present systematic review should be interpreted with caution due to the substantial lack of consistency in reporting and designing the existing validity studies.
A one-megabase physical map provides insights on gene organization in the enormous mitochondrial genome of cucumber
Authors: Bartoszewski Grzegorz , Gawronski Piotr , Szklarczyk Marek , Verbakel Henk , Havey Michael J.
Published: April 2009

Cucumber ( Cucumis sativus ) has one of the largest mitochondrial genomes known among all eukaryotes, due in part to the accumulation of short 20 to 60 bp repetitive DNA motifs. Recombination among these repetitive DNAs produces rearrangements affecting organization and expression of mitochondrial genes. To more efficiently identify rearrangements in the cucumber mitochondrial DNA, we built two nonoverlapping 800 and 220 kb BAC contigs and assigned major mitochondrial genes to these BACs. Polymorphism carried on the largest BAC contig was used to confirm paternal transmission. Mitochondrial genes were distributed across BACs and physically distant, although occasional clustering was observed. Introns in the nad1, nad4, and nad7 genes were larger than those reported in other plants, due in part to accumulation of short repetitive DNAs and indicating that increased intron sizes contributed to mitochondrial genome expansion in cucumber. Mitochondrial genes atp6 and atp9 are physically close to each other and cotranscribed. These physical contigs will be useful for eventual sequencing of the cucumber mitochondrial DNA, which can be exploited to more efficiently screen for unique rearrangements affecting mitochondrial gene expression.
The complete mitochondrial genome ofDiadegma semiclausum(Hymenoptera: Ichneumonidae) indicates extensive independent evolutionary events
Authors: Wei Shu-jun , Shi Min , He Jun-hua , Sharkey M. , Chen Xue-xin
Published: April 2009

Few complete mitochondrial genomes representing limited families in the order Hymenoptera have been sequenced. Here, we sequenced the complete mitochondrial genome of Diadegma semiclausum (Hymenoptera: Ichneumonidae). This genome is 18 728 bp long, the second largest hexapod mitochondrial genome sequenced in its entirety and that with the highest A+T content at 87.4%. Four tRNAs are rearranged compared with the ancestral arrangement. Gene rearrangement mechanisms are different among all three rearranged regions. Six tRNAs have a large variable loop, which is not found in other metazoan mitochondrial genomes. trnS(AGY)uses the abnormal anticodon TCT but trnK uses the normal CTT. The A+T-rich region is very long (2161 bp). An extremely A+T-rich (99.1%) 1515 bp tandem repeat region with three types of repeat elements is located between cox1 and cox2, and the most likely ancestral element originated from the 3′ end of cox1. Independent tandem duplications followed by mutation–insertion–deletion is the best model to explain the formation of this region. These results indicate that independent evolutionary events occurred extensively, such as gene rearrangement events, gene rearrangement mechanisms, derivation of tRNA variable loops, and tandem repeat region evolutionary processes, all of which likely contribute to the diversified features of hymenopteran mitochondrial genomes.
Karyotype variation in the albino rainbow trout (Oncorhynchus mykiss(Walbaum))
Authors: Ocalewicz K. , Dobosz S.
Published: April 2009

A Robertsonian polymorphism resulting in diploid chromosome number ranging from 59 to 61 and constant chromosome arm number (fundamental number = 104) was observed in the albino rainbow trout ( Oncorhynchus mykiss (Walbaum)) from the yellow color strain. In one individual, 90 mitotic chromosomes and 156 chromosome arms were counted, indicating the fish as a triploid. Morphology of the chromosomes, DAPI staining, and the cytogenetic location of 5S rDNA sequences showed sex-related chromosomal heteromorphism in the specimens. Additionally, length polymorphism of the X chromosome was detected in the studied individuals and two morphs of the X chromosome were described, XLand XS, according to the size of its short arm (p). The XSwas observed in the female as well as male albino rainbow trout; however, among females, no XSXSgenotype was found. After primed in situ labeling with 5S rDNA primers, the p-arms of both types of the X chromosome showed similar hybridization signals. On the other hand, fluorescence in situ hybridization with telomeric PNA (peptide nucleic acid) probe exhibited weak hybridization spots on the p-arm of the XSchromosome compared with the distinct hybridization spots observed on the XLp-arm. This could reflect a different telomere length on the p-arm of the XSand XLchromosomes. Partial translocation and deletion of the X chromosome p-arm are considered to be responsible for the p-arm length difference between the two morphological variants of X chromosome.
Molecular cytogenetic and agronomic characterization of advanced generations of wheat × triticale hybrids resistant toDiuraphis noxia(Mordvilko): application of GISH and microsatellite markers
Authors: Nkongolo K. K. , Haley S. D. , Kim N. S. , Michael P. , Fedak G. , Quick J. S. , Peairs F. B.
Published: April 2009

The PI 386148 triticale from Russia is among the highest resistant line to the Russian wheat aphid (RWA) ( Diuraphis noxia (Mordvilko)). This triticale line was used as the male parent in crosses with Lamar wheat ( Triticum aestivum L.). The F1plants were backcrossed to Lamar wheat. The progenies were tested for RWA biotype 1 reaction for at least eight backcross and selfing generations. Five lines from these selections were identified for their resistance to the RWA and their seeds were increased for agronomic and other characterizations. Molecular and cytological analyses of these lines were performed using genomic in situ hybridization and rye chromosome-specific microsatellites markers. Three lines were cytologically stable and carried a pair of rye ( Secale strictum (C. Presl) C. Presl) chromosomes as disomic addition lines of 1R. One line was unstable and showed a moderate level of mixoploidy with monosomic additions of 1R. Duplication of rye chromosome 1R was also identified. No wheat–rye chromosome interchange was detected, suggesting little homology between S. strictum and T. aestivum chromosomes. Specific microsatellite primers were used to identify the rye chromosomes present in each line. One rye chromosome, 1R, from the donor species contains genes for RWA resistance. Grain yield and test weight of three of the lines were similar to some adapted released wheat varieties under stress conditions.
Assignment of Aegilops variabilis Eig chromosomes and translocations carrying resistance to nematodes in wheat
Authors: Coriton Olivier , Barloy Dominique , Huteau Virginie , Lemoine Jocelyne , Tanguy Anne-Marie , Jahier Joseph
Published: April 2009

The allotetraploid species Aegilops variabilis Eig (2n = 28, UUSvSv) belongs to the tribe Triticeae and is closely related to wheat. One accession, Ae. variabilis No. 1, was found to be resistant to the cereal cyst nematode (CCN) and the root-knot nematode (RKN). As the genetic variability for resistance to those two pests is limited within wheat, this accession was crossed to bread wheat. Previous work enabled the development of two addition lines and two translocation lines carrying resistance. Here, we demonstrate, using genomic in situ hybridization, that there is no U–Sv interchange in the parental accession of Ae. variabilis. However, there are multiple rearrangements in the Sv chromosomes. The Ae. variabilis chromosome carrying the CreX gene for resistance to CCN combined segments with homoeology to wheat groups 1, 2, 4, and 6. The CreX gene belongs to the group 1 part and it was likely to have been introduced into chromosome 1BL at a similar location as the previously found QTL QCre.srd-1B for CCN resistance. The second Ae. variabilis chromosome carrying CreY and Rkn2 combined segments with homoeology to wheat groups 2, 4, and 7 on its short arm and group 3 on its long arm. It was designated as 3Sv. The two genes for resistance are carried by its long arm and have been transferred to wheat chromosome 3BL through homoeologous and genetically balanced recombination. Different SSR markers present in the introgressed segments could be used in marker-assisted selection.