bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Rcs phosphorelay system is specific to enteric pathogens/commensals and activates ydeI, a gene important for persistent Salmonella infection of mice
Authors: Erickson Kimberly D. , Detweiler Corrella S. 
Published: September 2006

SummaryBacteria utilize phosphorelay systems to respond to environmental or intracellular stimuli. Salmonella enterica encodes a four‐step phosphorelay system that involves two sensor kinase proteins, RcsC and RcsD, and a response regulator, RcsB. The physiological stimulus for Rcs phosphorelay activation is unknown; however, Rcs‐regulated genes can be induced in vitro by osmotic shock, low temperature and antimicrobial peptide exposure. In this report we investigate the role of the Rcs pathway using phylogenetic analysis and experimental techniques. Phylogenetic analysis determined that full‐length RcsC‐ and RcsD‐like proteins are generally restricted to Enterobacteriaceae species that have an enteric pathogenic or commensal relationship with the host. Experimental data show that RcsD and RcsB, in addition to RcsC, are important for systemic infection in mice and polymyxin B resistance in vitro. To identify Rcs‐regulated genes that confer these phenotypes, we took advantage of our observation that RcsA, a transcription factor and binding partner of RcsB, is not required for polymyxin B resistance or survival in mice. S. enterica serovar Typhimurium oligonucleotide microarrays were used to identify 18 loci that are activated by RcsC, RcsD and RcsB but not RcsA. Five of the 18 loci encode genes that contribute to polymyxin B resistance. One of these genes, ydeI, was shown by quantitative real‐time PCR to be regulated by the Rcs pathway independently of RcsA. Additionally, the stationary‐phase sigma factor, RpoS (sigmaS), regulates ydeI transcription. In vivo infections show that ydeI mutants are out‐competed by wild type 10‐ to 100‐fold after oral inoculation, but are only modestly attenuated after intraperitoneal inoculation. These data indicate that ydeI is an Rcs‐activated gene that plays an important role in persistent infection of mice, possibly by increasing bacterial resistance to antimicrobial peptides.
Competition of bacteriophage polypeptides with native replicase proteins for binding to the DNA sliding clamp reveals a novel mechanism for DNA replication arrest in Staphylococcus aureus
Authors: Belley Adam , Callejo Mario , Arhin Francis , Dehbi Mohammed , Fadhil Ibtihal , Liu Jing , McKay Geoffrey , Srikumar Ramakrishnan , Bauda Pascale , Ha Nhuan , DuBow Michael , Gros Philippe , Pelletier Jerry , Moeck Greg 
Published: September 2006

SummaryBacteriophages have evolved specific mechanisms that redirect bacterial metabolic pathways to the bacteriophage reproduction cycle. In this study, we characterized the bactericidal mechanism of two polypeptides from bacteriophages Twort and G1 that target the DNA sliding clamp of Staphylococcus aureus. The DNA sliding clamp, which tethers DNA polymerase to its template and thereby confers processivity upon the enzyme, was found to be essential for the viability of S. aureus. Expression of polypeptides TwortORF168 and G1ORF240 in S. aureus selectively inhibited DNA replication which in turn resulted in cell death. Both polypeptides specifically inhibited the S. aureus DNA replicase that was reconstituted in vitro but not the corresponding replicase of Streptococcus pyogenes. We demonstrated that inhibition of DNA synthesis is multifaceted and occurs via binding the DNA sliding clamp: TwortORF168 and G1ORF240 bound tightly to the DNA sliding clamp and prevented both its loading onto DNA and its interaction with DNA polymerase C. These results elucidate the impact of bacteriophage polypeptide expression upon DNA replication in the growing cell.
A loss‐of‐function mutation in AtYSL1 reveals its role in iron and nicotianamine seed loading
Authors: Jean Marie Le , Schikora Adam , Mari Stéphane , Briat Jean‐François , Curie Catherine 
Published: September 2006

SummaryThe Arabidopsis Yellow Stripe 1‐Like (YSL) proteins have been identified by homology with the maize (Zea mays) Yellow Stripe 1 (YS1) transporter which is responsible for iron–phytosiderophore (PS) uptake by roots in response to iron shortage. Although dicotyledonous plants do not synthesize PS, they do synthesize the PS precursor nicotianamine, a strong metal chelator essential for maintenance of iron homeostasis and copper translocation. Furthermore, ZmYS1 and the rice (Oryza sativa) protein OsYSL2 have metal‐nicotianamine transport activities in heterologous expression systems. In this work, we have characterized the function of AtYSL1 in planta. Two insertional loss‐of‐function ysl1 mutants of Arabidopsis were found to exhibit increased nicotianamine accumulation in shoots. More importantly, seeds of both ysl1 knockouts contained less iron and nicotianamine than wild‐type seeds, even when produced by plants grown in the presence of an excess of iron. This phenotype could be reverted by expressing the wild‐type AtYSL1 gene in ysl1 plants. ysl1 seeds germinated slowly, but this defect was rescued by an iron supply. AtYSL1 was expressed in the xylem parenchyma of leaves, where it was upregulated in response to iron excess, as well as in pollen and in young silique parts. This pattern is consistent with long‐distance circulation of iron and nicotianamine and their delivery to the seed. Taken together, our work provides strong physiological evidence that iron and nicotianamine levels in seeds rely in part on AtYSL1 function.
Inactivation of a European strain of West Nile virus in single‐ donor platelet concentrate using the INTERCEPT blood system
Authors: Gallian P. , Vignoli C. , Dombey A. M. , Mayaudon V. , Lin L. , Galichet V. , Cantaloube J. F. , De Micco P. 
Published: September 2006

Background and Objective  In order to prevent West Nile virus (WNV) contaminations by transfusion, the French National Blood Service decided to evaluate the INTERCEPT Blood System's efficiency on a European strain.Materials and Methods  Culture supernatant of WNV was used to infect six platelets concentrates. Viral titre was determined by plaque reduction neutralization test before and after viral inactivation using the INTERCEPT Blood System.Results  In all assays, the absence of plaque forming unit was observed after viral inactivation. The log reduction observed ranged between > 5·1 logs to > 5·2 logs.Conclusion  INTERCEPT Blood System is a commercially viral inactivation method potentially useful in order to prevent WNV transmission by blood products in France during re‐emerging outbreaks.
Keratomykose durchCylindrocarpon lichenicola
Authors: Kaben Ursula , Beck Ria , Tintelnot Kathrin 
Published: September 2006

ZusammenfassungWir berichten über zwei immunkompetente Männer, die im Abstand von wenigen Monaten an einer Keratomykose erkrankten. Als Erreger wurdeCylindrocarpon lichenicola(C. Massal.) D. Hawksworth angezüchtet. Als Infektionsquelle wurde bei einem der PatientenClematis‐Pflanzen in Erwägung gezogen. Von den Pflanzen konnte der Pilz nicht isoliert werden. Ein Trauma war nicht erinnerlich. Beide Patienten hatten keinen Kontakt miteinander und wohnten räumlich weit auseinander. Ein Patient erhielt während 12 Wochen Voriconazol (lokal und systemisch), der andere wurde lokal 6 Wochen mit Amphotericin B erfolgreich behandelt.Cylindrocarpon lichenicolabesitzt keratinolytische Eigenschaften und wurde kürzlich auf der Grundlage molekulargenetischer Untersuchungen alsFusarium lichenicolareklassifiziert.
Aldosterone breakthrough during therapy with angiotensin‐converting enzyme inhibitors and angiotensin II receptor blockers in proteinuric patients with immunoglobulin A nephropathy
Authors: HORITA YOSHIO , TAURA KOUICHI , TAGUCHI TAKASHI , FURUSU AKIRA , KOHNO SHIGERU 
Published: September 2006

SUMMARY:Background:  We are investigating whether aldosterone breakthrough negatively impacts on the antiproteinuric effects of angiotensin‐converting enzyme (ACE) inhibitors and/or angiotensin II receptor blockers (ARB).Methods:  We examine the role of aldosterone breakthrough in 43 normotensive, proteinuric (0.7 ± 0.3 g/day) outpatients (aged 41.5 ± 10.9 years) with immunoglobulin A nephropathy (IgAN) accompanied by stable renal function (creatinine clearance >50 mL/min). The patients were treated with temocapril (1 mg; n = 14), losartan (12.5 mg; n = 16), or a combination therapy (n = 13) for 12 months. We prospectively evaluated blood pressure (BP), urinary protein excretion (UPE), biochemical parameters and the renin‐angiotensin‐aldosterone system before and after 12 months of treatment.Results:  Although the overall plasma aldosterone concentrations values did not change after any of the treatments administered for 12 months, they eventually increased in 23 (temocapril, seven patients; losartan, eight patients; combination, seven patients) of the 43 patients (53.4%; aldosterone breakthrough), and fell in the remainder (46.6%). Blood pressure and renal function did not differ among the three groups at 12 months. In contrast, UPE was significantly higher in patients with, than without aldosterone breakthrough during temocapril and losartan administration. However, combination therapy induced a more remarkable reduction in UPE regardless of aldosterone breakthrough.Conclusions:  A combination of ACE inhibitors and ARB in normotensive patients with IgAN produces a more profound decrease in proteinuria than either monotherapy. This additive antiproteinuric effect is not dependent on aldosterone breakthrough. Additional larger, prospective, randomized studies will be needed for general acceptance of this strategy.
Can acidosis and hyperphosphataemia result in increased erythropoietin dosing in haemodialysis patients?
Authors: DISKIN CHARLES J , STOKES THOMAS J , DANSBY LINDA M , RADCLIFF LAUTREC , CARTER THOMAS B 
Published: September 2006

SUMMARY:Aim:  To evaluate whether factors such as acidosis and hyperphosphataemia that might cause an increased oxygen delivery to tissues could result in increased dosing requirements for intravenous erythropoietin (EPO) administration given to haemodialysis patients.Methods:  The clinical records of the patients seen at the Hypertension, Nephrology, Dialysis and Transplantation Clinic from December, 2004 through August, 2005 were reviewed to identify patients who had taken intravenous erythropoietin. Two‐tailed, Pearson’s correlation was performed to determine correlations between any of the parameters. Analysis of variance and stepwise regression for covariance were used to evaluate the relations of demographic and clinical characteristics and laboratory variables. Analysis of covariance and K means cluster analyses were also performed to examine linkage between variables. Kendall’s Tau correlation was used for correlations of non‐parametric data.Results:  There was a significant direct or positive correlation at the 0.01 levels between dry weight, age, intact parathyroid hormone level (PTH), and serum phosphorus and EPO dose. There was an inverse or negative correlation at that level between the serum bicarbonate and urea reduction ratio (URR) with the EPO dose at the same level while there was a weaker correlation but direct correlation between the white blood count (WBC) and EPO dose. There was significant colinearity between serum phosphorus and PTH but serum phosphorus showed a more significant correlation with EPO overall. Stepwise regression analysis for covariance revealed that phosphorus remained significantly correlated with EPO resistance after the removal of the effect of PTH while PTH lost its significance after the effect of phosphorus was removed.Conclusion:  Acidosis and hyperphosphataemia are associated with apparent increased erythropoietin dosing requirements. While this study did not evaluate the mechanism of such requirements and indeed many mechanisms might be possible, a rightward shift in the oxygen‐haemoglobin dissociation curve resulting in down‐regulation of erythropoietin receptors is considered consistent with the data and present knowledge.
RSI in pediatric anesthesia – is it used by nonpediatric anesthetists? A survey from south‐west England
Authors: STEDEFORD JUDITH , STODDART PETER 
Published: September 2006

SummaryBackground:  Rapid sequence induction (RSI) is the ‘gold standard’ technique for preventing aspiration of gastric contents during induction of anesthesia in unfasted patients. We conducted a survey to discover whether the conduct of RSI in children varies amongst anesthetists and if practice alters in relation to the time since training or degree of ongoing experience.Methods:  Six hundred and fifteen questionnaires were sent to anesthetists in the south‐west of England.Results:  The response rate was 61%. Preoxygenation was utilized by 83% of anesthetists for infants whereas 94% preoxygenated schoolchildren, P < 0.001. Only 59% of respondents used cricoid pressure in infants, compared with 96% in schoolchildren, P < 0.001. Propofol was the induction agent of choice for all anesthetists, although thiopentone was used more in infants (35%) than schoolchildren (9%), P < 0.001. Suxamethonium was widely used in all children. All anesthetists intubated patients for pyloromyotomy, 50% using cricoid pressure. RSI was performed by 86% of anesthetists for appendicectomy, with consultants most likely to deviate from a standard RSI. Sixty percent of anesthetists intubated for manipulation of forearm, 72% performing an RSI, 53% intubated for scrotal exploration, but only 42% performed an RSI.Conclusions:  Classical RSI is used for children by most anesthetists in south‐west England. RSI is modified for infants especially by more recently trained consultants. Suxamethonium is used less by consultant anesthetists. Whilst RSI is performed for appendicectomy there is a large variation in techniques for anesthetizing children for MUA and scrotal exploration which is independent of the grade of anesthetist.
Endosymbiosis in statu nascendi: close phylogenetic relationship between obligately endosymbiotic and obligately free‐living Polynucleobacter strains (Betaproteobacteria)
Authors: Vannini Claudia , Pöckl Matthias , Petroni Giulio , Wu Qinglong L. , Lang Elke , Stackebrandt Erko , Schrallhammer Martina , Richardson Paul M. , Hahn Martin W. 
Published: September 2006

SummaryBacterial strains affiliated to the phylogenetically shallow subcluster C (PnecC) of the Polynucleobacter cluster, which is characterized by a minimal 16S rRNA gene sequence similarity of approximately 98.5%, have been reported to occur as obligate endosymbionts of ciliates (Euplotes spp.), as well as to occur as free‐living cells in the pelagic zone of freshwater habitats. We investigated if these two groups of closely related bacteria represent strains fundamentally differing in lifestyle, or if they simply represent different stages of a facultative endosymbiotic lifestyle. The phylogenetic analysis of 16S rRNA gene and 16S‐23S ITS sequences of five endosymbiont strains from two different Euplotes species and 40 pure culture strains demonstrated host‐species‐specific clustering of the endosymbiont sequences within the PnecC subcluster. The sequences of the endosymbionts showed characteristics indicating an obligate endosymbiotic lifestyle. Cultivation experiments revealed fundamental differences in physiological adaptations, and determination of the genome sizes indicated a slight size reduction in endosymbiotic strains. We conclude that the two groups of PnecC bacteria represent obligately free‐living and obligately endosymbiotic strains, respectively, and do not represent different stages of the same complex life cycle. These closely related strains occupy completely separated ecological niches. To our best knowledge, this is the closest phylogenetic relationship between obligate endosymbionts and obligately free‐living bacteria ever revealed.
Rapid detection and enumeration of trh‐carrying Vibrio parahaemolyticus with the alkaline phosphatase‐labelled oligonucleotide probe
Authors: Raghunath Pendru , Pradeep Balakrishnan , Karunasagar Indrani , Karunasagar Iddya 
Published: September 2006

SummaryAn alkaline phosphatase (AP)‐labelled oligonucleotide probe was developed to detect and enumerate trh+Vibrio parahaemolyticus in seafood. The probe was evaluated using 40 isolates of V. parahaemolyticus, 45 isolates of other vibrios and 55 non‐vibrio isolates. The probe reacted specifically with V. parahaemolyticus possessing either the trh1 or trh2 variant of the trh gene and was found to be 100% specific for trh+V. parahaemolyticus. Using the trh probe, V. parahaemolyticus carrying trh gene was targeted in 34 seafood samples by direct plating and colony hybridization procedure. The trh+V. parahaemolyticus could be detected in five of 34 (14.7%) samples and the levels ranged from 5.0 × 102 to 3.4 × 103 cfu g−1. Colonies of trh+V.parahaemolyticus were isolated from the five positive samples. Forty seafood samples were analysed for trh+V. parahaemolyticus by colony hybridization following enrichment in alkaline peptone water. 16 samples (40%) were positive for trh gene and trh+V. parahaemolyticus was isolated from 15 samples (37.5%). To assess the sensitivity of the trh probe, seafood homogenates spiked with known concentrations of trh‐positive V. parahaemolyticus were plated and hybridized. Counts obtained using the probe were similar to those of inocula. The results suggest that the AP‐labelled trh probe is useful for the detection and enumeration of trh+V. parahaemolyticus in seafood.
Synchronization of cell death in a dinoflagellate population is mediated by an excreted thiol protease
Authors: Vardi Assaf , Eisenstadt Doron , Murik Omer , Berman‐Frank Ilana , Zohary Tamar , Levine Alex , Kaplan Aaron 
Published: September 2006

SummaryRegulated programmed cell death (PCD) processes have been documented in several phytoplankton species and are hypothesized to play a role in population dynamics. However, the mechanisms leading to the coordinated collapse of phytoplankton blooms are poorly understood. We showed that the collapse of the annual bloom of Peridinium gatunense, an abundant dinoflagellate in Lake Kinneret, Israel, is initiated by CO2 limitation followed by oxidative stress that triggers a PCD‐like cascade.We provide evidences that a protease excreted by senescing P. gatunense cells sensitizes younger cells to oxidative stress and may consequently trigger synchronized cell death of the population. Ageing of the P. gatunense cultures was characterized by a remarkable rise in DNA fragmentation and enhanced sensitivity to H2O2. Exposure of logarithmic phase (young) cultures to conditioning media from stationary phase (old) cells sensitized them to H2O2 and led to premature massive cell death. We detected the induction of specific extracellular protease activity, leupeptin‐sensitive, in ageing cultures and in lake waters during the succession of the P. gatunense bloom. Partial purification of the conditioned media revealed that this protease activity is responsible for the higher susceptibility of young cells to oxidative stress. Inhibition of the protease activity lowered the sensitivity to oxidative stress, whereas application of papain to logarithmic phase P. gatunense cultures mimicked the effect of the spent media and enhanced cell death. We propose a novel mechanistic framework by which a population of unicellular phytoplankton orchestrates a coordinated response to stress, thereby determine the fate of its individuals.
Vibrio anguillarum colonization of rainbow trout integument requires a DNA locus involved in exopolysaccharide transport and biosynthesis
Authors: Croxatto Antony , Lauritz Johan , Chen Chang , Milton Debra L. 
Published: September 2006

Summary Vibrio anguillarum, part of the normal flora of the aquatic milieu, causes a fatal haemorrhagic septicaemia in marine fish. In this study, a rainbow trout model was used to characterize the colonization of fish skin by V. anguillarum. Within 5 h after infection, the bacterium penetrated the skin mucosal layer, attached to the scales within 12 h, and formed a biofilm by 24–48 h. Two divergently transcribed putative operons, orf1‐wbfD‐wbfC‐wbfB and wza‐wzb‐wzc, were shown to play a role in skin colonization and virulence. The first operon encodes proteins of unknown function. The wza‐wzb‐wzc genes encode a secretin, tyrosine kinase and tyrosine phosphatase, respectively, which are similar to proteins in polysaccharide transport complexes. Compared with the wild type, polar mutations in wza, orf1 and wbfD caused a decrease in exopolysaccharide biosynthesis but not lipopolysaccharide biosynthesis. The wza and orf1 mutants did not attach to fish scales; whereas, the wbfD mutant had a wild‐type phenotype. Moreover, the wza and orf1 mutants had decreased exoprotease activity, in particular the extracellular metalloprotease EmpA, as well as mucinase activity suggesting that these mutations also affect exoenzyme secretion. Thus, the exopolysaccharide transport system in V. anguillarum is required for attachment to fish skin, possibly preventing mechanical removal of bacteria via natural sloughing of mucus.
DETECTING INFLUENTIAL OBSERVATIONS IN SLICED INVERSE REGRESSION ANALYSIS
Authors: Prendergast Luke A. 
Published: September 2006

SummaryThe detection of influential observations on the estimation of the dimension reduction subspace returned by Sliced Inverse Regression (SIR) is considered. Although there are many measures to detect influential observations in related methods such as multiple linear regression, there has been little development in this area with respect to dimension reduction. One particular influence measure for a version of SIR is examined and it is shown, via simulation and example, how this may be used to detect influential observations in practice.
AN EXCLUSIVE REGRESSORS BINARY MIXTURE MODEL WITH AN APPLICATION TO LABOUR SUPPLY
Authors: Lu Zeng‐Hua , Brown Bruce M. 
Published: September 2006

SummaryThis paper suggests a new type of mixture regression model, in which each mixture component is explained by its own regressors. Thus, the dependent variable can be driven by one of several unobservable explanatory mechanisms, each of which has its own distinct variables. An extension of the simulated annealing algorithm is introduced to fit this general mixture model. The paper also suggests a new technique for estimating the covariance matrix of estimators in a mixture model. Finally, empirical studies of a labour supply example show that our proposed model can perform much better than conventional logistic or mixture models.
AN ADAPTIVE TRIMMED LIKELIHOOD ALGORITHM FOR IDENTIFICATION OF MULTIVARIATE OUTLIERS
Authors: Clarke Brenton R. , Schubert Daniel D. 
Published: September 2006

SummaryThis article describes an algorithm for the identification of outliers in multivariate data based on the asymptotic theory for location estimation as described typically for the trimmed likelihood estimator and in particular for the minimum covariance determinant estimator. The strategy is to choose a subset of the data which minimizes an appropriate measure of the asymptotic variance of the multivariate location estimator. Observations not belonging to this subset are considered potential outliers which should be trimmed. For α less than about 0.5, the correct trimming proportion is taken to be thatα >  0for which the minimum of any minima of this measure of the asymptotic variance occurs. If no minima occur for anα > 0then the data set will be considered outlier free.