Detection of Iss and Bor on the surface of Escherichia coli

AIMS: To confirm the presence of Iss and Bor on the outer membrane of Escherichia coli using Western blots of outer membrane protein (OMP) preparations and fluorescence microscopy, and explore the use of fluorescence microscopy for the detection of avian pathogenic E. coli (APEC) and diagnosis of avian colibacillosis. METHODS AND RESULTS: Knockout mutants of iss and bor were created using a one-step recombination of target genes with PCR-generated antibiotic resistance cassettes. Anti-Iss monoclonal antibodies (Mabs) that cross-react with Bor protein were used to study the mutants relative to the wild-type organism. These Mabs were used as reagents to study OMP preparations of the mutants with Western blotting and intact E. coli cells with fluorescence microscopy. Iss and Bor were detected in Western blots of OMP preparations of the wild type. Also, Iss was detected on Deltabor mutants, and Bor was detected on Deltaiss mutants. Iss and Bor were also detected on the surface of the intact, wild-type cells and mutants using fluorescence microscopy. CONCLUSIONS: These results demonstrate that Bor and Iss are exposed on E. coli's outer membrane where they may be recognized by the host's immune system. SIGNIFICANCE AND IMPACT OF THE STUDY: To our knowledge, this is the first report confirming Iss' location in the outer membrane of an E. coli isolate. Such surface exposure has implications for the use of these Mabs for APEC detection and colibacillosis control.     

Identification of a novel two-partner secretion system from<Emphasis Type="Italic"> Burkholderia pseudomallei</Emphasis>

Two adjacent genes, bpaA and bpaB, whose products display significant similarity to a number of two-partner secretion (TPS) systems have been identified in Burkholderia pseudomallei strain 08, but are absent from the closely related avirulent species B. thailandensis. They possess a number of sequence features characteristic of TPS systems, including the presence of an NPNGI motif in a region of BpaA which strongly resembles a TPS secretion domain. BpaA is a very large protein (~530 kDa) and contains three repeats, each 600–800-amino acids long. Putative membrane-spanning regions in BpaB were identified through alignment with TpsB family members, and this also revealed an N-terminal extension not found in other TpsB proteins. The bpaA gene was found to be absent from the majority of B. pseudomallei strains. It appears that bpaAB are located within a putative genomic island that is inserted in close proximity to a methionine tRNA^CAT-encoding gene. Expression of BpaA was undetectable in cells grown in laboratory media. However, owing to the similarity of BpaA to known adhesin molecules, a potential role of BpaA in virulence was investigated in cell culture and in an animal model, but no evidence for such a role was found in these test systems.Communicated by W. Goebel     

Calculation of multipoint likelihoods using flanking marker data: a simulation study

The calculation of multipoint likelihoods is computationally challenging, with the exact calculation of multipoint probabilities only possible on small pedigrees with many markers or large pedigrees with few markers. This paper explores the utility of calculating multipoint likelihoods using data on markers flanking a hypothesized position of the trait locus. The calculation of such likelihoods is often feasible, even on large pedigrees with missing data and complex structures. Performance characteristics of the flanking marker procedure are assessed through the calculation of multipoint heterogeneity LOD scores on data simulated for Genetic Analysis Workshop 14 (GAW14). Analysis is restricted to data on the Aipotu population on chromosomes 1, 3, and 4, where chromosomes 1 and 3 are known to contain disease loci. The flanking marker procedure performs well, even when missing data and genotyping errors are introduced.     

Use of total lymphoid irradiation (TLI) in studies of the T cell-dependence of autoantibody production in rheumatoid arthritis

The effect of total lymphoid irradiation (TLI) on T cell-dependent and -independent humoral immune responses was studied in patients with intractable rheumatoid arthritis (RA). The serum levels of several autoantibodies and of antibodies to diphtheria (DT) and tetanus (TT) toxoids and to pneumococcal polysaccharide (PPS; 12 antigenic types) were studied before and after TLI. In addition, the patients were given a booster injection of DT and TT and a single injection of pneumococcal vaccine after radiotherapy. Antibody levels to DT and TT decreased about twofold after TLI and did not rise significantly (p greater than 0.05) after a booster injection. However, there was no reduction in antibody levels to PPS after TLI, and a significant rise in titers was observed after a single vaccination (p less than 0.01). The serum levels of rheumatoid factor (RF), anti-nuclear antibody (ANA), and granulocyte associated IgG rose slightly after TLI. Thus, the autoantibodies and antibodies to polysaccharides appear to be relatively independent of helper T cell function, which is markedly reduced after TLI. On the other hand, antibodies to protein antigens such as DT and TT appear to be more closely dependent upon T helper function in man, as has been reported in rodents. The findings suggest that T cell-independent autoantibody responses alone do not maintain the joint disease activity in RA, because improvement in joint disease after TLI has been reported.     

Constrained performance in a communication network: implications for the function of song-type matching and for the evolution of multiple ornaments

Many species of territorial songbirds exhibit a behavior known as song-type matching, in which a male sings the same song type that his neighbor is singing. Song-type matching is associated with increased aggression, but researchers have not come to a consensus on its adaptive function. Building on studies that identify singing performance as a variable relevant to sexual selection, we hypothesize that higher-performance singers benefit from matching their opponent's song type because matching improves eavesdroppers' ability to compare the two males' performances. We present a model of song-type choice that predicts that males that can outperform their rivals benefit by matching. In contrast, lower-performance males should avoid both matching and being matched. Our hypothesis is compatible with some existing hypotheses of song-matching function, but it is not compatible with the hypothesis that song matching is a conventional signal of aggression. We offer unique predictions that could be used to test our idea. We speculate that lower-performance individuals might have driven the evolution of repertoire complexity because they stand to benefit from novel, unmatchable songs. The phenomenon that dissimilar signals are less accurately compared than similar signals may favor the evolution of multiple ornaments and of plastic signal development (e.g., song learning) in general.     

Studies of steam decontamination of beef inoculated with Escherichia coli O157:H7 and its effect on subsequent storage

AIM: This study was carried out to determine the survival of Escherichia coli O157:H7 and subsequent shelf life of beef subjected to subatmospheric steam at differing temperatures. METHODS AND RESULTS: A specifically built, laboratory scale decontamination apparatus was used in decontamination trials to examine the effect of condensing steam at differing subatmospheric pressures on the survival of E. coli O157:H7 on meat. Beef slices were inoculated with a nontoxigenic E. coli O157:H7 strain and subjected to condensing steam at temperatures of 55, 65 and 75 degrees C. Following treatment, the decontaminated meat was packaged and stored in air or under vacuum at temperatures of 10 or 0 degrees C for up to 42 days. Microbiological analysis of the decontaminated and a control product (not subjected to any heat treatment) was carried out at regular intervals over the storage time of the product. Overall, significant reductions (ca 1.5 log(10) CFU cm(-2)) in pathogen numbers were observed at a steam treatment temperature of 75 degrees C, however, postprocess storage conditions were important in ensuring no re-growth of the pathogen and this was best achieved by storage under vacuum at 0 degrees C. CONCLUSIONS: Steam had a significant impact in reducing E. coli O157:H7 populations, but storage conditions post-treatment were important for ensuring inhibition of the pathogen. SIGNIFICANCE AND IMPACT OF THE STUDY: This study indicated that subatmospheric steam could have significant application in the decontamination of meat primals postfabrication, immediately prior to packaging thus ensuring a safer product for consumers.     

Shape based virtual screening and molecular docking towards designing novel pancreatic lipase inhibitors

Increase in obesity rates and obesity associated health issues became one of the greatest health concerns in the present world population. With alarming increase in obese percentage there is a need to design new drugs related to the obesity targets. Among the various targets linked to obesity, pancreatic lipase was one of the promising targets for obesity treatment. Using the in silico methods like structure based virtual screening, QikProp, docking studies and binding energy calculations three molecules namely zinc85531017, zinc95919096 and zinc33963788 from the natural database were reported as the potential inhibitors for the pancreatic lipase. Among them zinc95919096 presented all the interactions matching to both standard and crystal ligand and hence it can be further proceeded to drug discovery process.     

Ultrasound or near-infrared vascular imaging to guide peripheral intravenous catheterization in children: a pragmatic randomized controlled trial

Background:Peripheral intravenous catheterization in children is challenging, and success rates vary greatly. We conducted a pragmatic randomized controlled trial to determine whether the use of ultrasound or near-infrared vascular imaging to guide catheterization would be more effective than the standard approach in achieving successful catheter placement on the first attempt.Methods:We enrolled a convenience sample of 418 children in a pediatric emergency department who required peripheral intravenous catheterization between June 2010 to August 2012. We stratified them by age (≤ 3 yr and > 3 yr) and randomly assigned them to undergo the procedure with the standard approach, or with the help of either ultrasound or near-infrared vascular imaging. The primary outcome was the proportion of patients who had successful placement of a catheter on the first attempt.Results:The rate of successful first attempts did not differ significantly between either of the 2 intervention groups and the standard approach group (differences in proportions −3.9%, 95% confidence interval [CI] −14.2% to 6.5%, for ultrasound imaging; −8.7%, 95% CI −19.4% to 1.9%, for near-infrared imaging). Among children 3 years and younger, the difference in success rates relative to standard care was also not significant for ultrasound imaging (−9.6%, 95% CI −29.8% to 10.6%), but it was significantly worse for near-infrared imaging (−20.1%, 95% CI −40.1% to −0.2%). Among children older than 3 years, the differences in success rates relative to standard care were smaller but not significant (−2.3%, 95% CI −13.6% to 9.0%, for ultrasound imaging; −4.1%, 95% CI −15.7% to 7.5%, for near-infrared imaging). None of the pairwise comparisons were statistically significant in any of the outcomes.Interpretation:Neither technology improved first-attempt success rates of peripheral intravenous catheterization in children, even in the younger group. These findings do not support investment in these technologies for routine peripheral intravenous catheterization in children. Trial registration: ClinicalTrials.gov, no. {"type":"clinical-trial","attrs":{"text":"NCT01133652","term_id":"NCT01133652"}}NCT01133652.When painful procedures such as peripheral intraveneous catheterization are necessary for the medical care of children, the patients and their families want the first attempt to be successful.¹ Success rates of first attempt at intravenous catheter placement in children vary greatly, from 40%–76%, with up to 15 attempts reported in one case.^2–9 Failed procedures ensure further painful skin punctures, significant delays in urgent treatment, decreased efficiency and increased costs to the health care system.^10,11The standard procedure for peripheral intravenous catheterization involves placement of the needle in a location considered most likely to contain a vein, with the choice based on visualization and palpation of the vessel, knowledge of anatomy and experience of the practitioner, most often a nurse. Venous access in children can be challenging. Sick children may have low circulating blood volumes and may be cold or in shock, all of which can lead to peripheral vasoconstriction. Furthermore, young infants and toddlers have small vessels, often obscured by subcutaneous fat, and are less able to cooperate with painful procedures. The stress from struggling, crying and fear results in additional peripheral vasoconstriction of already small vessels due to sympathetic overdrive.Two adjunct technologies to facilitate intravenous catheterization in children have looked promising. Ultrasonography offers visual information about the size and depth of blood vessels, potentially facilitating intravenous placement of the needle in real time. Two small randomized trials of ultrasound imaging for intravenous placement in a pediatric emergency department setting have been published, but both had physicians as the ultrasonographers.^12,13 Near-infrared imaging devices project near-infrared light onto the skin, which is absorbed by deoxygenated hemoglobin. The invisible image of the underlying vascular pattern is captured by the device, processed and projected, in real time, back onto the patient’s skin using visible green light. This technology allows hands-free visualization of a vascular map to guide catheter placement.We performed a pragmatic randomized controlled trial to determine whether the use of either ultrasound or near-infrared vascular imaging would significantly improve the success rate of peripheral intravenous catheterization in children on first attempt by nurses compared with the standard approach.