Role of Pyocyanin and Extracellular DNA in Facilitating Pseudomonas aeruginosa Biofilm Formation

Pseudomonas aeruginosa is an opportunistic Gram‐negative bacterium that is primarily responsible for infections related to cystic fibrosis (CF) airways, burn wounds, urinary tract infections, surgery‐associated infections, and HIV‐related illness. Pyocyanin and extracellular DNA (eDNA) are the major factors dictating the progression of biofilm formation and infection. Pyocyanin is a potent virulence factor causing cell death in infected CF patients and is associated with high mortality. eDNA is a key player in P. aeruginosa biofilm formation and is also responsible for the high viscosity of CF sputum that blocks the respiratory airway passages. In this chapter, we summarize our recent findings on the role of pyocyanin in facilitating P. aeruginosa biofilm formation. Pyocyanin promotes eDNA release in P. aeruginosa by inducing cell lysis mediated via hydrogen peroxide (H2O2) production. Pyocyanin intercalates with the nitrogenous bases of DNA and creates structural perturbation on the double‐helix structure. Pyocyanin‐eDNA binding significantly influences P. aeruginosa cell surface hydrophobicity and influences the physicochemical interactions facilitating bacterial cell‐to‐cell interaction (aggregation) and ultimately facilitates robust biofilm formation. A pyocyanin knockout (ΔphzA‐G) mutant is shown to have significantly reduced eDNA release and biofilm formation in comparison to its wild‐type. To this end, we discover that antioxidant glutathione directly binds to pyocyanin and modulates pyocyanin structure and function, thus inhibiting pyocyanin‐eDNA binding and consequently hampering biofilm development

9286 Stars: An Agglomeration of Stellar Polarization Catalogs

This is a revision. The revisions are minor. The new version of the catalog should be used in preference to the old. The most serious error in the older version was that $\theta_diff$ was incorrect, being sometimes far too large, for Reiz and Franco entries; the correct values are all zero for that reference. We present an agglomeration of stellar polarization catalogs with results for 9286 stars. We have endeavored to eliminate errors, provide accurate (arcsecond) positions, sensibly weight multiple observations of the same star, and provide reasonable distances. This catalog is included as an ASCII file (catalog.txt) in the source of this submission.Comment: The most serious error in the older version was that $\theta_diff$ was incorrect, being sometimes far too large, for Reiz and Franco entries; the correct values are all zero for that reference. 11 pages, no figures. Accepted for Astronomical Journal. Catalog also available as an ASCII file by anonymous FTP from ftp://vermi.berkeley.edu/pub/polcat/p14.ou

IS element IS16 as a molecular screening tool to identify hospital-associated strains of Enterococcus faecium

<p>Abstract</p> <p>Background</p> <p>Hospital strains of <it>Enterococcus faecium </it>could be characterized and typed by various molecular methods (MLST, AFLP, MLVA) and allocated to a distinct clonal complex known as MLST CC17. However, these techniques are laborious, time-consuming and cost-intensive. Our aim was to identify hospital <it>E. faecium </it>strains and differentiate them from colonizing and animal variants by a simple, inexpensive and reliable PCR-based screening assay. We describe here performance and predictive value of a single PCR detecting the insertion element, IS<it>16</it>, to identify hospital <it>E. faecium </it>isolates within a collection of 260 strains of hospital, animal and human commensal origins.</p> <p>Methods</p> <p>Specific primers were selected amplifying a 547-bp fragment of IS<it>16</it>. Presence of IS<it>16 </it>was determined by PCR screenings among the 260 <it>E. faecium </it>isolates. Distribution of IS<it>16 </it>was compared with a prevalence of commonly used markers for hospital strains, <it>esp </it>and <it>hyl</it>_<it>Efm</it>. All isolates were typed by MLST and partly by PFGE. Location of IS<it>16 </it>was analysed by Southern hybridization of plasmid and chromosomal DNA.</p> <p>Results</p> <p>IS<it>16 </it>was exclusively distributed only among 155 invasive strains belonging to the clonal complex of hospital-associated strains ("CC17"; 28 MLST types) and various vancomycin resistance genotypes (<it>van</it>A/B/negative). The five invasive IS<it>16</it>-negative strains did not belong to the clonal complex of hospital-associated strains (CC17). IS<it>16 </it>was absent in all but three isolates from 100 livestock, food-associated and human commensal strains ("non-CC17"; 64 MLST types). The three IS<it>16</it>-positive human commensal isolates revealed MLST types belonging to the clonal complex of hospital-associated strains (CC17). The values predicting a hospital-associated strain ("CC17") deduced from presence and absence of IS<it>16 </it>was 100% and thus superior to screening for the presence of <it>esp </it>(66%) and/or <it>hyl</it>_{<it>Efm </it>}(46%). Southern hybridizations revealed chromosomal as well as plasmid localization of IS<it>16</it>.</p> <p>Conclusions</p> <p>This simple screening assay for insertion element IS<it>16 </it>is capable of differentiating hospital-associated from human commensal, livestock- and food-associated <it>E. faecium </it>strains and thus allows predicting the epidemic strengths or supposed pathogenic potential of a given <it>E. faecium </it>isolate identified within the nosocomial setting.</p

IS element IS16 as a molecular screening tool to identify hospital-associated strains of Enterococcus faecium

<p>Abstract</p> <p>Background</p> <p>Hospital strains of <it>Enterococcus faecium </it>could be characterized and typed by various molecular methods (MLST, AFLP, MLVA) and allocated to a distinct clonal complex known as MLST CC17. However, these techniques are laborious, time-consuming and cost-intensive. Our aim was to identify hospital <it>E. faecium </it>strains and differentiate them from colonizing and animal variants by a simple, inexpensive and reliable PCR-based screening assay. We describe here performance and predictive value of a single PCR detecting the insertion element, IS<it>16</it>, to identify hospital <it>E. faecium </it>isolates within a collection of 260 strains of hospital, animal and human commensal origins.</p> <p>Methods</p> <p>Specific primers were selected amplifying a 547-bp fragment of IS<it>16</it>. Presence of IS<it>16 </it>was determined by PCR screenings among the 260 <it>E. faecium </it>isolates. Distribution of IS<it>16 </it>was compared with a prevalence of commonly used markers for hospital strains, <it>esp </it>and <it>hyl</it>_<it>Efm</it>. All isolates were typed by MLST and partly by PFGE. Location of IS<it>16 </it>was analysed by Southern hybridization of plasmid and chromosomal DNA.</p> <p>Results</p> <p>IS<it>16 </it>was exclusively distributed only among 155 invasive strains belonging to the clonal complex of hospital-associated strains ("CC17"; 28 MLST types) and various vancomycin resistance genotypes (<it>van</it>A/B/negative). The five invasive IS<it>16</it>-negative strains did not belong to the clonal complex of hospital-associated strains (CC17). IS<it>16 </it>was absent in all but three isolates from 100 livestock, food-associated and human commensal strains ("non-CC17"; 64 MLST types). The three IS<it>16</it>-positive human commensal isolates revealed MLST types belonging to the clonal complex of hospital-associated strains (CC17). The values predicting a hospital-associated strain ("CC17") deduced from presence and absence of IS<it>16 </it>was 100% and thus superior to screening for the presence of <it>esp </it>(66%) and/or <it>hyl</it>_{<it>Efm </it>}(46%). Southern hybridizations revealed chromosomal as well as plasmid localization of IS<it>16</it>.</p> <p>Conclusions</p> <p>This simple screening assay for insertion element IS<it>16 </it>is capable of differentiating hospital-associated from human commensal, livestock- and food-associated <it>E. faecium </it>strains and thus allows predicting the epidemic strengths or supposed pathogenic potential of a given <it>E. faecium </it>isolate identified within the nosocomial setting.</p

Dynamics of Line-Driven Winds from Disks in Cataclysmic Variables. I. Solution Topology and Wind Geometry

We analyze the dynamics of 2-D stationary, line-driven winds from accretion disks in cataclysmic variable stars. The driving force is that of line radiation pressure, in the formalism developed by Castor, Abbott & Klein for O stars. Our main assumption is that wind helical streamlines lie on straight cones. We find that the Euler equation for the disk wind has two eigenvalues, the mass loss rate and the flow tilt angle with the disk. Both are calculated self-consistently. The wind is characterized by two distinct regions, an outer wind launched beyond four white dwarf radii from the rotation axis, and an inner wind launched within this radius. The inner wind is very steep, up to 80 degrees with the disk plane, while the outer wind has a typical tilt of 60 degrees. In both cases the ray dispersion is small. We, therefore, confirm the bi-conical geometry of disk winds as suggested by observations and kinematical modeling. The wind collimation angle appears to be robust and depends only on the disk temperature stratification. The flow critical points lie high above the disk for the inner wind, but close to the disk photosphere for the outer wind. Comparison with existing kinematical and dynamical models is provided. Mass loss rates from the disk as well as wind velocity laws are discussed in a subsequent paper.Comment: 21 pages, 10 Postscript figures; available also from http://www.pa.uky.edu/~shlosman/publ.html. Astrophysical Journal, submitte

A Possible Periodicity in the Radio Lightcurves of 3C454.3

During the period 1966.5 - 2006.2 the 15GHz and 8GHz lightcurves of 3C454.3 (z=0.859) show a qsasi-periodicity of ~12.8 yr (~6.9 yr in the rest frame of the source) with a double-bump structure. This periodic behaviour is interpreted in terms of a rotating double-jet model in which the two jets are created from the black holes in a binary system and rotate with the period of the orbital motion. The periodic variations in the radio fluxes of 3C454.3 are suggested to be mainly due to the lighthouse effects (or the variation in Doppler boosting) of the precessing jets which are caused by the orbital motion. In addition, variations in the mass-flow rates accreting onto the black holes may be also involved.Comment: 15 pages, 11 figure

An investigation of the impact of data breach severity on the readability of mandatory data breach notification letters: evidence from U.S. firms

The aim of this article is to investigate the impact of data breach severity on the readability of mandatory data breach notification letters. Using a content analysis approach to determine data breach severity attributes (measured by the total number of breached records, type of data accessed, the source of the data breach, and how the data were used), in conjunction with readability measures (reading complexity, numerical intensity, length of letter, word size, and unique words), 512 data breach incidents from 281 U.S. firms across the 2012–2015 period were examined. The results indicate that data breach severity has a positive impact on reading complexity, length of letter, word size, and unique words, and a negative impact on numerical terms. Interpreting the results collectively through the lens of impression management, it can be inferred that business managers may be attempting to obfuscate bad news associated with high data breach severity incidents by manipulating syntactical features of the data breach notification letters in a way that makes the message difficult for individuals to comprehend. The study contributes to the information studies and impression management behavior literatures by analyzing linguistic cues in notifications following a data breach incident

All solutions of the localization equations for N=2 quantum black hole entropy

We find the most general bosonic solution to the localization equations describing the contributions to the quantum entropy of supersymmetric black holes in four-dimensional N=2 supergravity coupled to n_v vector multiplets. This requires the analysis of the BPS equations of the corresponding off-shell supergravity (including fluctuations of the auxiliary fields) with AdS2 \times S2 attractor boundary conditions. Our work completes and extends the results of arXiv:1012.0265 that were obtained for the vector multiplet sector, to include the fluctuations of all the fields of the off-shell supergravity. We find that, when the auxiliary SU(2) gauge field strength vanishes, the most general supersymmetric configuration preserving four supercharges is labelled by n_v+1 real parameters corresponding to the excitations of the conformal mode of the graviton and the scalars of the n_v vector multiplets. In the general case, the localization manifold is labelled by an additional SU(2) triplet of one-forms and a scalar function.Comment: 27 page

Holographic renormalization and supersymmetry

Holographic renormalization is a systematic procedure for regulating divergences in observables in asymptotically locally AdS spacetimes. For dual boundary field theories which are supersymmetric it is natural to ask whether this defines a supersymmetric renormalization scheme. Recent results in localization have brought this question into sharp focus: rigid supersymmetry on a curved boundary requires specific geometric structures, and general arguments imply that BPS observables, such as the partition function, are invariant under certain deformations of these structures. One can then ask if the dual holographic observables are similarly invariant. We study this question in minimal N = 2 gauged supergravity in four and five dimensions. In four dimensions we show that holographic renormalization precisely reproduces the expected field theory results. In five dimensions we find that no choice of standard holographic counterterms is compatible with supersymmetry, which leads us to introduce novel finite boundary terms. For a class of solutions satisfying certain topological assumptions we provide some independent tests of these new boundary terms, in particular showing that they reproduce the expected VEVs of conserved charges.Comment: 70 pages; corrected typo

Energy security and shifting modes of governance

The concept of energy security fits uneasily into contemporary security debates. It is neither a clearly traditional nor a fully ‘non-traditional’ security issue. There are also limits to the social constructedness of the concept. This article argues that, while it is important to identify the differing securitizations of energy, these must be contextualized within the material realities and the differing historical modes of governance of the political economy of resources. This is essential for understanding the differing meanings accorded to energy security, the shifting modes through which energy is governed, and the extent to which energy security concerns drive international politics. In this context, contemporary concerns over energy security have both material and ideological dimensions: anxiety over the dual shift of power from West to East and from resource-importing to resource-exporting countries; and concern over the normative weakening of the neo-liberal mode of energy governance