bluuebunny/crossref_metadata_2025 huggingface dataset:
Upper limb joint kinetic analysis during tennis serve: Assessment of competitive level on efficiency and injury risks
Authors: Martin C. , Bideau B. , Ropars M. , Delamarche P. , Kulpa R.
Published: January 2013

The aim of this work was to compare the joint kinetics and stroke production efficiency for the shoulder, elbow, and wrist during the serve between professionals and advanced tennis players and to discuss their potential relationship with given overuse injuries. Eleven professional and seven advanced tennis players were studied with an optoelectronic motion analysis system while performing serves. Normalized peak kinetic values of the shoulder, elbow, and wrist joints were calculated using inverse dynamics. To measure serve efficiency, all normalized peak kinetic values were divided by ball velocity. t‐tests were used to determine significant differences between the resultant joint kinetics and efficiency values in both groups (advanced vs professional). Shoulder inferior force, shoulder anterior force, shoulder horizontal abduction torque, and elbow medial force were significantly higher in advanced players. Professional players were more efficient than advanced players, as they maximize ball velocity with lower joint kinetics. Since advanced players are subjected to higher joint kinetics, the results suggest that they appeared more susceptible to high risk of shoulder and elbow injuries than professionals, especially during the cocking and deceleration phases of the serve.
Using Online Reviews in Social Care
Authors: Trigg Lisa
Published: January 2013

The emphasis placed on choice of social care provider means that there is an increasing need to furnish service users with reliable and up‐to‐date information on provider quality. In England, encouraging users to leave online feedback on providers is seen as one of the ways of improving the supply of information. However, using these channels for social care raises a number of issues, for example, the challenge of generating enough content to be of value, and the need to protect the anonymity of potentially vulnerable users. This article aims to summarize these issues, by drawing upon the experience of an established ratings site (TripAdvisor), and of heath service rating systems, as well as literature on decision‐making and behaviour across social care and related sectors. The article concludes that online ratings can assist users to choose providers, however, they will need to be supported by carefully designed processes to maximize their usefulness.
Immunoprofiling reveals unique cell‐specific patterns of wall epitopes in the expanding Arabidopsis stem
Authors: Hall Hardy C. , Cheung Jingling , Ellis Brian E.
Published: January 2013

The Arabidopsis inflorescence stem undergoes rapid directional growth, requiring massive axial cell‐wall extension in all its tissues, but, at maturity, these tissues are composed of cell types that exhibit markedly different cell‐wall structures. It is not clear whether the cell‐wall compositions of these cell types diverge rapidly following axial growth cessation, or whether compositional divergence occurs at earlier stages in differentiation, despite the common requirement for cell‐wall extensibility. To examine this question, seven cell types were assayed for the abundance and distribution of 18 major cell‐wall glycan classes at three developmental stages along the developing inflorescence stem, using a high‐throughput immunolabelling strategy. These stages represent a phase of juvenile growth, a phase displaying the maximum rate of stem extension, and a phase in which extension growth is ceasing. The immunolabelling patterns detected demonstrate that the cell‐wall composition of most stem tissues undergoes pronounced changes both during and after rapid extension growth. Hierarchical clustering of the immunolabelling signals identified cell‐specific binding patterns for some antibodies, including a sub‐group of arabinogalactan side chain‐directed antibodies whose epitope targets are specifically associated with the inter‐fascicular fibre region during the rapid cell expansion phase. The data reveal dynamic, cell type‐specific changes in cell‐wall chemistry across diverse cell types during cell‐wall expansion and maturation in the Arabidopsis inflorescence stem, and highlight the paradox between this structural diversity and the uniform anisotropic cell expansion taking place across all tissues during stem growth.
Coagulopathy after traumatic brain injury: incidence, pathogenesis, and treatment options
Authors: Maegele Marc
Published: January 2013

Coagulopathy after traumatic brain injury (TBI) is frequent and represents a powerful predictor related to outcome and prognosis. The complex pathophysiological mechanisms of the coagulopathy of TBI are multifactorial and remain still undefined. The nature of the coagulation abnormalities differs between severe TBI and non‐TBI with somatic injuries. The current hypothesis for the development of coagulopathy after TBI includes combinations of both hypo‐ and hypercoagulable states promoted by the magnitude and the extent of the injury resulting in a variable degree of secondary injury via subsequent ischemic and hemorrhagic lesioning. The proposed underlying mechanisms may comprise the release of tissue factor (TF), hyperfibrinolysis, shock, and hypoperfusion thus triggering the protein C pathway, disseminated intravascular coagulation, and platelet dysfunction. Hemocoagulative disorders after TBI may be amenable to treatment, and adequate and timely management may protect from secondary injury and poor outcomes. Functional assays such as viscoelastic tests may be supportive in early detection, diagnosis, and guidance of treatment. This review summarizes the current understanding with regard to frequency, pathogenesis, diagnosis, and treatment of the coagulopathy after TBI.
International Climate Finance and Its Influence on Fairness and Policy
Authors: Pittel Karen , Rübbelke Dirk
Published: January 2013

Besides costs and benefits, fairness aspects tend to influence negotiating parties’ willingness to join an international agreement on climate change mitigation. Fairness is largely considered to improve the prospects of success of international negotiations and hence measures raising fairness perception might – in turn – help to bring about effective cooperative international climate change mitigation. We consider the influences present international support of climate policy in developing countries exerts on fairness perception and how this again might affect international negotiations. In doing so we distinguish between fairness perception that is based on historical experiences and perception that is based on conjectures about opponents’ intentions. By identifying beneficial components of current support schemes lessons can be learnt for designing new schemes like the Green Climate Fund.
Association between plasma transfusions and clinical outcome in critically ill children: a prospective observational study
Authors: Karam O. , Lacroix J. , Robitaille N. , Rimensberger P. C. , Tucci M.
Published: January 2013

Background and Objectives

Plasma transfusions are commonly used in adult and paediatric intensive care units. Recent data suggest an association between plasma transfusions and worse clinical outcome in adult trauma patients. To date, no prospective paediatric study has addressed this issue. Our objective was to prospectively analyse the association between plasma transfusions and clinical outcome of critically ill children.

Materials and Methods

Prospective, observational and single centre study that includes all consecutive admissions to a tertiary level multidisciplinary paediatric critical care unit over a 1‐year period. The primary outcome measure was the incidence after transfusion of new or progressive multiple organ dysfunction syndrome. Secondary outcome measures included nosocomial infections, intensive care unit length of stay and 28‐day mortality. Odds ratios were adjusted for weight, severity of illness, coagulopathy, plasma transfusions prior to admission, need for extracorporeal life support and transfusion of other labile blood products.

Results

A total of 831 patients were enrolled, among which 94 (11%) received at least one plasma transfusion. In the latter group of patients, the adjusted odds ratio for an increased incidence of new or progressive multiple organ dysfunction syndrome was 3·2 (P = 0·002). There was also a significant difference in the occurrence of nosocomial infections and intensive care unit length of stay, but no significant difference in the 28‐day mortality.

Conclusions

In critically ill children, plasma transfusions seem to be independently associated with an increased occurrence of new or progressive multiple organ dysfunction syndrome, nosocomial infections and prolonged length of stay.
Mechanisms underlying regional differences in the Ca2+ sensitivity of BKCa current in arteriolar smooth muscle
Authors: Yang Yan , Sohma Yoshiro , Nourian Zahra , Ella Srikanth R. , Li Min , Stupica Aaron , Korthuis Ronald J. , Davis Michael J. , Braun Andrew P. , Hill Michael A.
Published: January 2013

Key points

The plasma membrane large‐conductance Ca2+‐activated, K+ channel (BKCa) is a major ion channel contributing to the regulation of membrane potential.

Activation of large‐conductance Ca2+‐activated K+ channel by both depolarization and increased intracellular Ca2+ results in hyperpolarization that acts to limit agonist and mechanically induced vasoconstriction in small arteries.

Using patch‐clamp techniques we demonstrate that regional differences exist in how BKCa is regulated, particularly with respect to its Ca2+ sensitivity.

Using single‐channel recordings and siRNA to manipulate protein subunit expression, it is argued that the β1‐subunit plays a more dominant role in cerebral blood vessels as compared with small arteries from skeletal muscle.

Subtle differences in the regulation of membrane potential in different vascular beds allow local blood flow and pressure to be closely adapted to the tissue's metabolic needs.

Abstract  β1‐Subunits enhance the gating properties of large‐conductance Ca2+‐activated K+ channels (BKCa) formed by α‐subunits. In arterial vascular smooth muscle cells (VSMCs), β1‐subunits are vital in coupling SR‐generated Ca2+ sparks to BKCa activation, affecting contractility and blood pressure. Studies in cremaster and cerebral VSMCs show heterogeneity of BKCa activity due to apparent differences in the functional β1‐subunit:α‐subunit ratio. To define these differences, studies were conducted at the single‐channel level while siRNA was used to manipulate specific subunit expression. β1 modulation of the α‐subunit Ca2+ sensitivity was studied using patch‐clamp techniques. BKCa channel normalized open probability (NPo) versus membrane potential (Vm) curves were more left‐shifted in cerebral versus cremaster VSMCs as cytoplasmic Ca2+ was raised from 0.5 to 100 μm. Calculated V1/2 values of channel activation decreased from 72.0 ± 6.1 at 0.5 μm Ca2+i to −89 ± 9 mV at 100 μm Ca2+i in cerebral compared with 101 ± 10 to −63 ± 7 mV in cremaster VSMCs. Cremaster BKCa channels thus demonstrated an ∼2.5‐fold weaker apparent Ca2+ sensitivity such that at a value of Vm of −30 mV, a mean value of [Ca2+]i of 39 μm was required to open half of the channels in cremaster versus 16 μm[Ca2+]i in cerebral VSMCs. Further, shortened mean open and longer mean closed times were evident in BKCa channel events from cremaster VSMCs at either −30 or 30 mV at any given [Ca2+]. β1‐Subunit‐directed siRNA decreased both the apparent Ca2+ sensitivity of BKCa in cerebral VSMCs and the appearance of spontaneous transient outward currents. The data are consistent with a higher ratio of β1‐subunit:α‐subunit of BKCa channels in cerebral compared with cremaster VSMCs. Functionally, this leads both to higher Ca2+ sensitivity and NPo for BKCa channels in the cerebral vasculature relative to that of skeletal muscle.
AMP‐activated protein kinase is required for exercise‐induced peroxisome proliferator‐activated receptor γ co‐activator 1α translocation to subsarcolemmal mitochondria in skeletal muscle
Authors: Smith Brennan K. , Mukai Kazutaka , Lally James S. , Maher Amy C. , Gurd Brendon J. , Heigenhauser George J. F. , Spriet Lawrence L. , Holloway Graham P.
Published: January 2013

Key points

The transcriptional co‐activator peroxisome proliferator‐activated receptor γ co‐activator 1α (PGC‐1α), in concert with mitochondrial transcription factor A (Tfam), has been implicated in the direct regulation of the mitochondrial genome.

In humans, rats and mice, acute exercise was found to promote PGC‐1α translocation to subsarcolemmal (SS) mitochondria.

In rats, treatment with 5‐aminoimidazole‐4‐carboxamide‐1‐β‐ribofuranoside induced both PGC‐1α and Tfam translocation and in addition PGC‐1α and Tfam were found to co‐locolize with α‐tubulin.

In mice, rendering AMP‐activated protein kinase (AMPK) inactive prevented PGC‐1α translocation.

These data suggest that exercise causes translocation of PGC‐1α preferentially to SS mitochondria in an AMPK‐dependent manner.

Abstract  In skeletal muscle, mitochondria exist as two subcellular populations known as subsarcolemmal (SS) and intermyofibrillar (IMF) mitochondria. SS mitochondria preferentially respond to exercise training, suggesting divergent transcriptional control of the mitochondrial genomes. The transcriptional co‐activator peroxisome proliferator‐activated receptor γ co‐activator 1α (PGC‐1α) and mitochondrial transcription factor A (Tfam) have been implicated in the direct regulation of the mitochondrial genome in mice, although SS and IMF differences may exist, and the potential signalling events regulating the mitochondrial content of these proteins have not been elucidated. Therefore, we examined the potential for PGC‐1α and Tfam to translocate to SS and IMF mitochondria in human subjects, and performed experiments in rodents to identify signalling mechanisms regulating these translocation events. Acute exercise in humans and rats increased PGC‐1α content in SS but not IMF mitochondria. Acute exposure to 5‐aminoimidazole‐4‐carboxamide‐1‐β‐ribofuranoside in rats recapitulated the exercise effect of increased PGC‐1α protein within SS mitochondria only, suggesting that AMP‐activated protein kinase (AMPK) signalling is involved. In addition, rendering AMPK inactive (AMPK kinase dead mice) prevented exercise‐induced PGC‐1α translocation to SS mitochondria, further suggesting that AMPK plays an integral role in these translocation events. In contrast to the conserved PGC‐1α translocation to SS mitochondria across species (humans, rats and mice), acute exercise only increased mitochondrial Tfam in rats. Nevertheless, in rat resting muscle PGC‐1α and Tfam co‐immunoprecipate with α‐tubulin, suggesting a common cytosolic localization. These data suggest that exercise causes translocation of PGC‐1α preferentially to SS mitochondria in an AMPK‐dependent manner.
The Mechanisms of Material Removal in the Fluidized Bed Machining of Polyvinyl Chloride Substrates
Authors: Barletta M. , Tagliaferri V. , Trovalusci F. , Veniali F. , Gisario A.
Published: January 2013

In this paper, the mechanisms of material removal during the fluidized bed machining (FBM) of polymeric substrates are analyzed. Cylindrical components composed of polyvinyl chloride (PVC) were exposed to the impact of abrasives while rotating at high speed within a fluidization column. The interaction between the Al2O3 abrasive media and the PVC surfaces was studied to identify the effect of the main process parameters, such as the machining time, the abrasive mesh size, and the rotational speed. The change in the surface morphology as a function of the process parameters was evaluated using field emission gun—scanning electron microscopy (FEG-SEM) and contact gauge profilometry. An improvement in the finishing of the processed surfaces was achieved, and the related mechanisms were identified. The roles of the impact speed and the contact conditions between the abrading particles and the substrate were also investigated.
The Knee Loading Apparatus: Axial, Anterior, and Compressive Loading With Magnetic Resonance Imaging
Authors: Küpper Jessica C. , Robu Ion , Frayne Richard , Ronsky Janet L.
Published: January 2013

When magnetic resonance (MR) images are collected while applying a load to the knee joint, additional information about the joint response to loading can be acquired such as cartilage deformation, whole joint and ligament stiffness, or physiological estimates of weight-bearing joint positions. To allow load application and controlled lower limb movement in supine MR imaging, the knee loading apparatus (KLA) was designed to apply safe and physiologically relevant controlled loads to the knee joint, position the knee through a range of flexion angles, and operate successfully in a magnetic environment. The KLA is composed of three main components: a remotely operated custom hydraulic loading system, a logic system that interfaces with the user, and modular non ferromagnetic positioning frames. Three positioning frames are presented for application to anterior tibial loading, tibiofemoral compression, and patellofemoral compression at multiple knee flexion angles. This system design makes improvements over current devices. Safe remotely applied loads (hydraulic loading system) can be applied by either subject or tester and in multiple locations simultaneously. Additionally, loads can be altered at any time in a continuous manner without electrical interference. Transportability was improved due to a smaller footprint. The KLA has the flexibility to attach any positioning frame with many possible loading scenarios without changing the loading mechanism or logic systems, and allows force values over time to be output rather than estimated. An evaluation of the load repeatability (within 7% of applied load) and accuracy (0.5–14.9%) demonstrates the feasibility of this design for investigations into in vivo knee joint responses to loading.
Assembly-Free Large-Scale Modal Analysis on the Graphics-Programmable Unit
Authors: Yadav Praveen , Suresh Krishnan
Published: January 2013

Popular eigensolvers such as block-Lanczos require repeated inversion of an eigenmatrix. This is a bottleneck in large-scale modal problems with millions of degrees of freedom. On the other hand, the classic Rayleigh–Ritz conjugate gradient method only requires a matrix-vector multiplication, and is therefore potentially scalable to such problems. However, as is well-known, the Rayleigh–Ritz has serious numerical deficiencies, and has largely been abandoned by the finite-element community. In this paper, we address these deficiencies through subspace augmentation, and consider a subspace augmented Rayleigh–Ritz conjugate gradient method (SaRCG). SaRCG is numerically stable and does not entail explicit inversion. As a specific application, we consider the modal analysis of geometrically complex structures discretized via nonconforming voxels. The resulting large-scale eigenproblems are then solved via SaRCG. The voxelization structure is also exploited to render the underlying matrix-vector multiplication assembly-free. The implementation of SaRCG on multicore central processing units (CPUs) and graphics-programmable units (GPUs) is discussed, followed by numerical experiments and case-studies.
Co-Evolutionary Optimization for Multi-Objective Design Under Uncertainty
Authors: Filomeno Coelho Rajan
Published: January 2013

This paper focuses on multi-objective optimization under uncertainty for mechanical design, through a reliability-based formulation referring to the concept of probabilistic nondominance. To address this problem, the implementation of a co-evolutionary strategy is advocated, consisting of the concurrent evolution of two intertwined populations optimized according to coupled subproblems: the upper level optimizer handles the design variables, whereas the corresponding values of the probabilistic thresholds for the objectives (namely the reliable nondominated front) are retrieved at the lower stage. The proposed methodology is successfully applied to six analytical test cases, as well as to the sizing optimization of two truss structures, demonstrating an improved capacity to cover wider ranges of the reliable nondominated front in comparison with all-at-once strategies tackling all types of variables simultaneously.
Interior Ballistic Modeling and Simulation for Different Charge Zones in Modular Charge System
Authors: Ma Changjun , Zhang Xiaobing
Published: January 2013

The modular charge is developed to replace the conventional bagged charge systems for many advantages. In the interior ballistic cycle of a modular charge system, the nonsimultaneous ignition of propellant in different cases results in an increasing pressure wave, and can cause a launch safety problem of the gun. Because the charge structure is complicated, it is hard to simulate the interior ballistics process for the modular charge system currently. To simulate the interior ballistic of the modular charge system more accurately, an improved interior ballistic one-dimensional two phase flow model for modular charge system is established. The improvement of this model lies in that it takes account of the discontinuity of the propelling charge bed, the block of the cartridge wall to the flame spreading in propelling charge bed, effects of modular cartridge movement to the interior ballistic performance, the nonsimultaneous breakup of the modular charge cartridges, the ignition of the propelling charge in different cartridges, and flame spreading through the cap of the core tubes. Simulation for a full charge and three lower charge cases with different charge position were carried out based on the model. The simulation results proved that the model is reliable, and can be used to study the effects of cartridge mechanical properties, charge position, different charge zones on interior ballistic performance of modular charges.
Performance Calculation of Shaped Charges With Shear-Formed Liners
Authors: Rassokha S. S. , Ladov S. V. , Kubyshkina G. A. , Babkin A. V.
Published: January 2013

Production of shear-formed liners for rotating shaped charges is of interest since it causes the jet self-spinning effect, which drastically affects the penetration process. A novel four-part methodology for calculating the performance parameters of such charges is suggested. First, the liner strained state is related to the feed rate and mandrel angular velocity during the shear-forming process. Second, based on the polycrystal plasticity theory, a methodology for determining the liner's plastic anisotropy parameters depending on its strained state is realized. Third, a general dependence of the jet angular velocity on the liner plastic anisotropy parameters is obtained. The fourth part presents the methodology of shaped charge performance calculation with respect to spinning effects. The results of calculations performed according to the suggested methodology are in good agreement with experimental data. Calculations also show that the penetration depth increases 9% to 15% compared to a spinning shaped charge with a drawn liner (i.e., without the self-spinning effect) when the self-spinning jet rotates oppositely to the shaped charge. When they rotate in the same direction, penetration depth decreases critically (more than 50%).
Metal contact printing photolithography for fabrication of submicrometer patterned sapphire substrates for light-emitting diodes
Authors: Hsieh Yi-Ta , Lee Yung-Chun
Published: January 2013

This paper reports an improved method that combines a metal film contact printing method with traditional photolithography for fabrication of submicrometer-scale patterned sapphire substrates (PSSs) used for high-brightness light-emitting diodes (LEDs). First, a patterned metal thin film is transferred from the surface of a mold onto a photoresist (PR) layer deposited on top of the sapphire substrate. The transferred metal pattern acts as a photomask for subsequent photolithographic processes. PR structures with a high aspect ratio of 5 and a small line width of 500 nm are fabricated on 2 and 4 in. sapphire wafers. Finally, inductively coupled plasma etching is performed on the sapphire substrates to obtain PSSs by using the patterned PR microstructures as an etching mask. Experiments have been performed and both 2 and 4 in. PSSs with submicrometer-scaled and cone-shaped surface features were successfully obtained. These PSSs can be used in the LED industry to obtain high-brightness LEDs.
Quantum Back-Action of an Individual Variable-Strength Measurement
Authors: Hatridge M. , Shankar S. , Mirrahimi M. , Schackert F. , Geerlings K. , Brecht T. , Sliwa K. M. , Abdo B. , Frunzio L. , Girvin S. M. , Schoelkopf R. J. , Devoret M. H.
Published: January 2013

Tracking Quantum Evolution

The actual process of measuring a quantum system has an effect on the result making the outcome unpredictable. Using a superconducting qubit placed in a microwave cavity,

Hatridge
et al.

(p.
178
) found that a series of partial measurements on a quantum system left the system in a pure state. Looking at the record of the actual measurements allowed the final state of a superconducting-based quantum system to be determined accurately. Such control is crucial for achieving full feedback control of a general quantum system.
Multiple Fitness Peaks on the Adaptive Landscape Drive Adaptive Radiation in the Wild
Authors: Martin Christopher H. , Wainwright Peter C.
Published: January 2013

Pupfish Speciation

Evolution moves along phenotypic trajectories that can be visualized as a topographic landscape of multiple peaks of relatively high-fitness and low-fitness valleys.
Martin and Wainwright
(p.
208
) examined the adaptive landscape of three species of
Cyprinodon
pupfishes. These species represent a recent adaptive radiation, each having moved into a difference niche within their specialized environment. Examining replicate hybrid transplants relative to parental types in high- and low-density enclosures, the authors recovered the specialist parental phenotypes and observed higher survival and growth. Thus, high density can drive multiple fitness peaks during the early stages of adaptive radiation.
Inoculum Effects of Ceftobiprole, Daptomycin, Linezolid, and Vancomycin with Staphylococcus aureus and Streptococcus pneumoniae at Inocula of 105and 107CFU Injected into Opposite Thighs of Neutropenic Mice
Authors: Lee Dong-Gun , Murakami Yoichi , Andes David R. , Craig William A.
Published: January 2013

Reduced bactericidal efficacy at a high inoculum is known as the inoculum effect (IE). We used neutropenic mice to compare the IEs of ceftobiprole (CFB), daptomycin (DAP), linezolid (LZD), and vancomycin (VAN) against 6 to 9 strains ofStaphylococcus aureusand 4 strains ofStreptococcus pneumoniaeat 2 inocula in opposite thighs of the same mice. Neutropenic mice had 104.5to 105.7CFU/thigh (low inoculum [LI]) in one thigh and 106.4to 107.2CFU/thigh (high inoculum [HI]) in the opposite thigh when treated for 24 h with subcutaneous (s.c.) doses every 12 h of DAP at 0.024 to 100 mg/kg of body weight and LZD at 0.313 to 320 mg/kg and s.c. doses every 6 h of CFB at 0.003 to 160 mg/kg and VAN at 0.049 to 800 mg/kg. Dose-response data were analyzed by a maximum effect (Emax) model using nonlinear regression. Static doses for each drug and at each inoculum were calculated, and the difference between HI and LI (IE index) gave the magnitude of IE for each drug-organism combination. Mean (range) IE indexes ofS. aureuswere 2.9 (1.7 to 4.6) for CFB, 4.1 (2.6 to 9.3) for DAP, 4.6 (1.7 to 7.1) for LZD, and 10.1 (6.3 to 20.3) for VAN. InS. pneumoniae, the IE indexes were 2.5 (1.3 to 3.3) for CFB, 2.0 (1.6 to 2.8) for DAP, 1.9 (1.7 to 2.2) for LZD, and 1.5 (0.8 to 3.2) for VAN; these values were similar for all drugs. InS. aureus, the IE was much larger with VAN than with CFB, DAM, and LZD (P< 0.05). Anin vivotime course of vancomycin activity showed initiation of killing at 4- to 16-fold-higher doses at HI than at LI despite similar initial growth of controls.
Direct and Indirect Anti-Inflammatory Effects of Tulathromycin in Bovine Macrophages: Inhibition of CXCL-8 Secretion, Induction of Apoptosis, and Promotion of Efferocytosis
Authors: Fischer Carrie D. , Beatty Jennifer K. , Duquette Stephanie C. , Morck Douglas W. , Lucas Merlyn J. , Buret André G.
Published: January 2013

Recent evidence indicates that immunomodulation by antibiotics may enhance their clinical efficacy. Specifically, drug-induced leukocyte apoptosis and macrophage efferocytosis have been shown to promote the resolution of inflammation in a variety of disease settings. Tulathromycin is a new macrolide antibiotic for the treatment of bovine respiratory disease. The direct antimicrobial effects of the drug alone do not fully justify its superior clinical efficacy, and we hypothesize that tulathromycin may have immunomodulating properties. We recently reported that tulathromycin promotes apoptosis and inhibits proinflammatory NF-κB signaling in bovine neutrophils. In this study, we investigated the direct and indirect anti-inflammatory effects of tulathromycin in bovine macrophages. The findings indicate that bovine monocyte-derived macrophages and alveolar macrophages readily phagocytose tulathromycin-induced apoptotic neutrophils bothin vitroand in the airways ofMannheimia haemolytica-infected calves. Moreover, tulathromycin promotes delayed, concentration-dependent apoptosis, but not necrosis, in bovine macrophagesin vitro. Activation of caspase-3 and detection of mono- and oligonucleosomes in bovine monocyte-derived macrophages treated with tulathromycin was observed 12 h posttreatment; pretreatment with a pan-caspase inhibitor (ZVAD) blocked the proapoptotic effects of the drug. Lastly, tulathromycin inhibited the secretion of proinflammatory CXCL-8 in lipopolysaccharide (LPS)-stimulated bovine macrophages; this effect was independent of caspase activation or programmed cell death. Taken together, these immunomodulating effects observed in bovine macrophages help further elucidate the mechanisms through which tulathromycin confers anti-inflammatory and proresolution benefits. Furthermore, these findings offer novel insights on how antibiotics may offer anti-inflammatory benefits by modulating macrophage-mediated events that play a key role in inflammation.
Activities of Fosfomycin, Tigecycline, Colistin, and Gentamicin against Extended-Spectrum-β-Lactamase-Producing Escherichia coli in a Foreign-Body Infection Model
Authors: Corvec Stéphane , Furustrand Tafin Ulrika , Betrisey Bertrand , Borens Olivier , Trampuz Andrej
Published: January 2013

Limited antimicrobial agents are available for the treatment of implant-associated infections caused by fluoroquinolone-resistant Gram-negative bacilli. We compared the activities of fosfomycin, tigecycline, colistin, and gentamicin (alone and in combination) against a CTX-M15-producing strain of
Escherichia coli
(Bj HDE-1)
in vitro
and in a foreign-body infection model. The MIC and the minimal bactericidal concentration in logarithmic phase (MBC
log
) and stationary phase (MBC
stat
) were 0.12, 0.12, and 8 μg/ml for fosfomycin, 0.25, 32, and 32 μg/ml for tigecycline, 0.25, 0.5, and 2 μg/ml for colistin, and 2, 8, and 16 μg/ml for gentamicin, respectively. In time-kill studies, colistin showed concentration-dependent activity, but regrowth occurred after 24 h. Fosfomycin demonstrated rapid bactericidal activity at the MIC, and no regrowth occurred. Synergistic activity between fosfomycin and colistin
in vitro
was observed, with no detectable bacterial counts after 6 h. In animal studies, fosfomycin reduced planktonic counts by 4 log
10
CFU/ml, whereas in combination with colistin, tigecycline, or gentamicin, it reduced counts by >6 log
10
CFU/ml. Fosfomycin was the only single agent which was able to eradicate
E. coli
biofilms (cure rate, 17% of implanted, infected cages). In combination, colistin plus tigecycline (50%) and fosfomycin plus gentamicin (42%) cured significantly more infected cages than colistin plus gentamicin (33%) or fosfomycin plus tigecycline (25%) (
P
< 0.05). The combination of fosfomycin plus colistin showed the highest cure rate (67%), which was significantly better than that of fosfomycin alone (
P
< 0.05). In conclusion, the combination of fosfomycin plus colistin is a promising treatment option for implant-associated infections caused by fluoroquinolone-resistant Gram-negative bacilli.
Placental Transfer of Maraviroc in an
Ex Vivo
Human Cotyledon Perfusion Model and Influence of ABC Transporter Expression
Authors: Vinot C. , Gavard L. , Tréluyer J. M. , Manceau S. , Courbon E. , Scherrmann J. M. , Declèves X. , Duro D. , Peytavin G. , Mandelbrot L. , Giraud C.
Published: January 2013

Nowadays, antiretroviral therapy is recommended during pregnancy to prevent mother-to-child transmission of HIV. However, for many antiretroviral drugs, including maraviroc, a CCR5 antagonist, very little data exist regarding placental transfer. Besides, various factors may modulate this transfer, including efflux transporters belonging to the ATP-binding cassette (ABC) transporter superfamily. We investigated maraviroc placental transfer and the influence of ABC transporter expression on this transfer using the human cotyledon perfusion model. Term placentas were perfused
ex vivo
for 90 min with maraviroc (600 ng/ml) either in the maternal-to-fetal (
n
= 10 placentas) or fetal-to-maternal (
n
= 6 placentas) direction. Plasma concentrations were determined by ultra performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). Fetal transfer rates (FTR) and clearance indexes (CLI) were calculated as ratios of fetal to maternal concentrations at steady state (mean values between 30 and 90 min) and ratios of FTR of maraviroc to that of antipyrine, respectively. ABC transporter gene expression levels were determined by quantitative reverse transcription (RT)-PCR and ABCB1 protein expression by Western blotting. For the maternal-to-fetal direction, the mean FTR and CLI were 8.0% ± 3.0 and 0.26 ± 0.07, respectively, whereas the mean CLI was 0.52 ± 0.23 for the fetal-to-maternal direction. We showed a significant inverse correlation between maraviroc CLI and
ABCC2
,
ABCC10
, and
ABCC11
placental gene expression levels (
P
< 0.05). To conclude, we report a low maraviroc placental transfer probably involving ABC efflux transporters and thus in all likelihood associated with a limited fetal exposition. Nevertheless, these results would need to be supported by
in vivo
data obtained from paired maternal and cord blood samples.
Reduced Vancomycin Susceptibility in anIn VitroCatheter-Related Biofilm Model Correlates with Poor Therapeutic Outcomes in Experimental Endocarditis Due to Methicillin-Resistant Staphylococcus aureus
Authors: Abdelhady Wessam , Bayer Arnold S. , Seidl Kati , Nast Cynthia C. , Kiedrowski Megan R. , Horswill Alexander R. , Yeaman Michael R. , Xiong Yan Q.
Published: January 2013

Staphylococcus aureusis the most common cause of endovascular infections, including catheter sepsis and infective endocarditis (IE). Vancomycin (VAN) is the primary choice for treatment of methicillin-resistantS. aureus(MRSA) infections. However, high rates of VAN treatment failure in MRSA infections caused by VAN-susceptible strains have been increasingly reported. Biofilm-associated MRSA infections are especially prone to clinical antibiotic failure. The present studies examined potential relationships between MRSA susceptibility to VAN in biofilmsin vitroand nonsusceptibility to VAN in endovascular infectionin vivo. Using 10 “VAN-susceptible” MRSA bloodstream isolates previously investigated for VAN responsiveness in experimental IE, we studied the mechanism(s) of suchin vivoVAN resistance, including: (i) VAN binding to MRSA organisms; (ii) the impact of VAN on biofilm formation and biofilm composition; (iii) VAN efficacy in anin vitrocatheter-related biofilm model; (iv) effects on cell wall thickness. As a group, the five strains previously categorized as VAN nonresponders (non-Rsp) in the experimental IE model differed from the five responders (Rsp) in terms of lower VAN binding, increased biofilm formation, higher survival in the presence of VAN within biofilms in the presence or absence of catheters, and greater biofilm reduction upon proteinase K treatment. Interestingly, sub-MICs of VAN significantly promoted biofilm formation only in the non-Rsp isolates. Cell wall thickness was similar among all MRSA strains. These results suggest that sublethal VAN levels that induce biofilm formation and reduce efficacy of VAN in thein vitrocatheter-associated biofilms may contribute to suboptimal treatment outcomes for endovascular infections caused by “VAN-susceptible” MRSA strains.
Single- and Multiple-Dose Study To Determine the Safety, Tolerability, and Pharmacokinetics of Ceftaroline Fosamil in Combination with Avibactam in Healthy Subjects
Authors: Riccobene Todd A. , Su Sheng Fang , Rank Douglas
Published: January 2013

This study was conducted to determine the safety, tolerability, and pharmacokinetics of intravenous doses of ceftaroline fosamil administered in combination with the novel non-β-lactam β-lactamase inhibitor avibactam in healthy adults. In the single-dose, open-label arm, 12 subjects received single 1-h intravenous infusions of ceftaroline fosamil alone (600 mg), avibactam alone (600 mg), and ceftaroline fosamil in combination with avibactam (600/600 mg) separated by 5-day washout periods. In the multiple-dose, placebo-controlled, double-blind arm, 48 subjects received intravenous infusions of ceftaroline fosamil/avibactam at 600/600 mg every 12 h (q12h), 400/400 mg q8h, 900/900 mg q12h, 600/600 mg q8h, or placebo for 10 days. Ceftaroline and avibactam levels in plasma and urine were measured by liquid chromatography coupled with tandem mass spectrometry. No significant differences in systemic exposure of ceftaroline or avibactam were observed when the drugs were administered alone versus concomitantly, indicating that there was no apparent pharmacokinetic interaction between ceftaroline fosamil and avibactam administered as a single dose. No appreciable accumulation of either drug occurred with multiple intravenous doses of ceftaroline fosamil/avibactam, and pharmacokinetic parameters for ceftaroline and avibactam were similar on days 1 and 10. Infusions of ceftaroline fosamil/avibactam were well tolerated at total daily doses of up to 1,800 mg of each compound, and all adverse events (AEs) were mild to moderate in severity. Infusion-site reactions were the most common AEs reported with multiple dosing. The pharmacokinetic and safety profiles of ceftaroline fosamil/avibactam demonstrate that the 2 drugs can be administered concomitantly to provide an important broad-spectrum antimicrobial treatment option.
Activities of Drug Combinations against Mycobacterium tuberculosis Grown in Aerobic and Hypoxic Acidic Conditions
Authors: Piccaro Giovanni , Giannoni Federico , Filippini Perla , Mustazzolu Alessandro , Fattorini Lanfranco
Published: January 2013

Mycobacterium tuberculosis
is exposed to hypoxia and acidity within granulomatous lesions. In this study, an acidic culture model of
M. tuberculosis
was used to test drug activity against aerobic 5-day-old (A5) and hypoxic 5-, 12-, and 19-day-old (H5, H12, and H19, respectively) bacilli after 7, 14, and 21 days of exposure. In A cultures, CFU and pH rapidly increased, while in H cultures growth stopped and pH increased slightly. Ten drugs were tested: rifampin (R), isoniazid (I), pyrazinamide (Z), ethambutol (E), moxifloxacin (MX), amikacin (AK), metronidazole (MZ), nitazoxanide (NZ), niclosamide (NC), and PA-824 (PA). Rifampin was the most active against A5, H5, H12, and H19 bacilli. Moxifloxacin and AK efficiently killed A5 and H5 cells, I was active mostly against A5 cells, Z was most active against H12 and H19 cells, and E showed low activity. Among nitrocompounds, NZ, NC, and PA were effective against A5, H5, H12, and H19 cells, while MZ was active against H12 and H19 cells. To kill all A and H cells, A5- and H5-active agents R, MX, and AK were used in combination with MZ, NZ, NC, or PA, in comparison with R-I-Z-E, currently used for human therapy. Mycobacterial viability was determined by CFU and a sensitive test in broth (day to positivity, MGIT 960 system). As shown by lack of regrowth in MGIT, the most potent combination was R-MX-AK-PA, which killed all A5, H5, H12, and H19 cells in 14 days. These observations demonstrate the sterilizing effect of drug combinations against cells of different
M. tuberculosis
stages grown in aerobic and hypoxic acidic conditions.
Microbial Translocation in the Pathogenesis of HIV Infection and AIDS
Authors: Marchetti Giulia , Tincati Camilla , Silvestri Guido
Published: January 2013

In pathogenic simian immunodeficiency virus (SIV) and human immunodeficiency virus (HIV) infections, the translocation of microbial products from the gastrointestinal (GI) tract to portal and systemic circulation has been proposed as a major driver of the chronic immune activation that is associated with disease progression. Consistently, microbial translocation is not present in nonpathogenic SIV infections of natural host species.
In vivo
studies demonstrated that HIV/SIV-associated microbial translocation results from a series of immunopathological events occurring at the GI mucosa: (i) early and severe mucosal CD4
+
depletion, (ii) mucosal immune hyperactivation/persistent inflammation; (iii) damage to the integrity of the intestinal epithelium with enterocyte apoptosis and tight junction disruption; and (iv) subverted the gut microbiome, with a predominance of opportunistic bacteria. Direct
in situ
evidence of microbial translocation has been provided for SIV-infected rhesus macaques showing translocated microbial products in the intestinal lamina propria and distant sites. While the mechanisms by which microbial translocation causes immune activation remain controversial, a key pathogenic event appears to be innate immunity activation via Toll-like receptors and other pathogen recognition receptors. Accumulating clinical observations suggest that microbial translocation might affect HIV disease progression, response to therapy, and non-AIDS comorbidities. Given its detrimental effect on overall immunity, several interventions to prevent/block microbial translocation are currently under investigation as novel therapeutic agents for HIV/AIDS.
Human Rhinoviruses
Authors: Jacobs Samantha E. , Lamson Daryl M. , St. George Kirsten , Walsh Thomas J.
Published: January 2013

Human rhinoviruses (HRVs), first discovered in the 1950s, are responsible for more than one-half of cold-like illnesses and cost billions of dollars annually in medical visits and missed days of work. Advances in molecular methods have enhanced our understanding of the genomic structure of HRV and have led to the characterization of three genetically distinct HRV groups, designated groups A, B, and C, within the genusEnterovirusand the familyPicornaviridae. HRVs are traditionally associated with upper respiratory tract infection, otitis media, and sinusitis. In recent years, the increasing implementation of PCR assays for respiratory virus detection in clinical laboratories has facilitated the recognition of HRV as a lower respiratory tract pathogen, particularly in patients with asthma, infants, elderly patients, and immunocompromised hosts. Cultured isolates of HRV remain important for studies of viral characteristics and disease pathogenesis. Indeed, whether the clinical manifestations of HRV are related directly to viral pathogenicity or secondary to the host immune response is the subject of ongoing research. There are currently no approved antiviral therapies for HRVs, and treatment remains primarily supportive. This review provides a comprehensive, up-to-date assessment of the basic virology, pathogenesis, clinical epidemiology, and laboratory features of and treatment and prevention strategies for HRVs.
Genome-Wide Identification of Genes Required for Fitness of Group A Streptococcus in Human Blood
Authors: Le Breton Yoann , Mistry Pragnesh , Valdes Kayla M. , Quigley Jeffrey , Kumar Nikhil , Tettelin Hervé , McIver Kevin S.
Published: January 2013

The group A streptococcus (GAS) is a strict human pathogen responsible for a wide spectrum of diseases. Although GAS genome sequences are available, functional genomic analyses have been limited. We developed a
mariner
-based transposon,
osKaR
, designed to perform Transposon-Site Hybridization (TraSH) in GAS and successfully tested its use in several invasive serotypes. A complex
osKaR
mutant library in M1T1 GAS strain 5448 was subjected to negative selection in human blood to identify genes important for GAS fitness in this clinically relevant environment. Mutants underrepresented after growth in blood (output pool) compared to growth in rich media (input pool) were identified using DNA microarray hybridization of transposon-specific tags
en masse
. Using blood from three different donors, we identified 81 genes that met our criteria for reduced fitness in blood from at least two individuals. Genes known to play a role in survival of GAS in blood were found, including those encoding the virulence regulator Mga (
mga
), the peroxide response regulator PerR (
perR
), and the RofA-like regulator Ralp-3 (
ralp3
). We also identified genes previously reported for their contribution to sepsis in other pathogens, such as
de novo
nucleotide synthesis (
purD
,
purA
,
pyrB
,
carA
,
carB
,
guaB
), sugar metabolism (
scrB
,
fruA
), zinc uptake (
adcC
), and transcriptional regulation (
cpsY
). To validate our findings, independent mutants with mutations in 10 different genes identified in our screen were confirmed to be defective for survival in blood bactericidal assays. Overall, this work represents the first use of TraSH in GAS to identify potential virulence genes.
ToxR Recognizes a Direct Repeat Element in the
toxT
,
ompU
,
ompT
, and
ctxA
Promoters of Vibrio cholerae To Regulate Transcription
Authors: Goss Thomas J. , Morgan Sarah J. , French Emily L. , Krukonis Eric S.
Published: January 2013

ToxR facilitates TcpP-mediated activation of the
toxT
promoter in
Vibrio cholerae
, initiating a regulatory cascade that culminates in cholera toxin secretion and toxin coregulated pilus expression. ToxR binds a region from −104 to −68 of the
toxT
promoter, from which ToxR recruits TcpP to the TcpP-binding site from −53 to −38. To precisely define the ToxR-binding site within the
toxT
promoter, promoter derivatives with single-base-pair transversions spanning the ToxR-footprinted region were tested for transcription activation and DNA binding. Nine transversions between −96 to −83 reduced
toxT
promoter activity 3-fold or greater, and all nine reduced the relative affinity of the
toxT
promoter for ToxR at least 2-fold, indicating that activation defects were due largely to reduced binding of ToxR to the
toxT
promoter. Nucleotides important for ToxR-dependent
toxT
activation revealed a consensus sequence of TNAAA-N
5
-TNAAA extending from −96 to −83, also present in other ToxR-regulated promoters. When these consensus nucleotides were mutated in the
ompU
,
ompT
, or
ctxA
promoters, ToxR-mediated regulation was disrupted. Thus, we have defined the core ToxR-binding site present in numerous ToxR-dependent promoters and we have precisely mapped the binding site for ToxR to a position three helical turns upstream of TcpP in the
toxT
promoter.