bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Botulinum-A Toxin Injection into Bulbospongiosus Muscle on Ejaculation Latency in Male Rats
Authors: Serefoglu Ege C. , Hawley Wayne R. , Lasker George F. , Grissom Elin M. , Mandava Sree H. , Sikka Suresh C. , Dohanich Gary P. , Hellstrom Wayne J.G.
Published: April 2014

Introduction

Premature ejaculation (PE) is the most common male sexual dysfunction. A variety of pharmacotherapeutic strategies have been employed to treat men suffering with lifelong PE. However, there are currently no pharmaceuticals approved by the U.S. Food and Drug Administration specifically designed for PE treatment.

Aim

Given that the bulbospongiosus muscle is involved in the ejaculatory reflex in both humans and rodents and that local administration of botulinum-A can abolish muscle contractions, the current study examined the effect of injection of botulinum-A toxin into the bulbospongiosus muscle on the ejaculatory latency of male rats.

Methods

After screening for normal sexual activity with sexually receptive female rats, 33 sexually experienced male Long-Evans rats (Harlan Laboratories, Indianapolis, IN, USA) underwent an additional four pretreatment sexual exposures over the course of the following week, during which all components of sexual behavior were video recorded by trained observers. On the day after their fourth experience, rats were anesthetized and received a single injection of either 0.5 unit (n = 11) or 1 unit (n = 11) of botulinum-A toxin or saline vehicle (n = 11). Botulinum-A toxin was dissolved in 0.1 mL of saline vehicle and injected bilaterally into the bulbospongiosus muscle by the percutaneous route. Beginning 2 days after treatment, sexual behaviors were reexamined over the course of the following week on four separate occasions.

Main Outcome Measures

The latency to achieve ejaculation, and the frequencies and latencies of mounts and intromissions were video recorded by trained observers in a blinded fashion.

Results

Relative to pretreatment measurements, bilateral injection of saline vehicle into the bulbospongiosus muscle did not affect ejaculation latencies. However, rats treated with either 0.5 or 1 unit of botulinum-A toxin exhibited significantly longer latencies to achieve ejaculation relative to pretreatment performance. Of note, botulinum-A toxin did not affect the ability to achieve mounts, intromissions, or ejaculation.

Conclusions

These results demonstrate that botulinum-A toxin injection into the bulbospongiosus muscle is a safe and effective treatment that extends ejaculatory latency in rats without affecting the ability to engage in sexual activity or achieve ejaculation. Further studies are required to evaluate this therapeutic concept in PE patients.
3‐D laser images of splash‐form tektites and their use in aerodynamic numerical simulations of tektite formation
Authors: Samson C. , Butler S. , Fry C. , McCausland P. J. A. , Herd R. K. , Sharomi O. , Spiteri R. J. , Ralchenko M.
Published: April 2014

Ten splash‐form tektites from the Australasian strewn field, with masses ranging from 21.20 to 175.00 g and exhibiting a variety of shapes (teardrop, ellipsoid, dumbbell, disk), have been imaged using a high‐resolution laser digitizer. Despite challenges due to the samples’ rounded shapes and pitted surfaces, the images were combined to create 3‐D tektite models, which captured surface features with a high fidelity (≈30 voxel mm−2) and from which volume could be measured noninvasively. The laser‐derived density for the tektites averaged 2.41 ± 0.11 g cm−3. Corresponding densities obtained via the Archimedean bead method averaged 2.36 ± 0.05 g cm−3. In addition to their curational value, the 3‐D models can be used to calculate the tektites’ moments of inertia and rotation periods while in flight, as a probe of their formation environment. Typical tektite rotation periods are estimated to be on the order of 1 s. Numerical simulations of air flow around the models at Reynolds numbers ranging from 1 to 106 suggest that the relative velocity of the tektites with respect to the air must have been <10 m s−1 during viscous deformation. This low relative velocity is consistent with tektite material being carried along by expanding gases in the early time following the impact.
Correlated accretion ages and ε54Cr of meteorite parent bodies and the evolution of the solar nebula
Authors: Sugiura Naoji , Fujiya Wataru
Published: April 2014

We look at the relationship between the value of ε54Cr in bulk meteorites and the time (after calcium‐aluminum‐rich inclusion, CAI) when their parent bodies accreted. To obtain accretion ages of chondrite parent bodies, we estimated the maximum temperature reached in the insulated interior of each parent body, and estimated the initial 26Al/27Al for this temperature to be achieved. This initial 26Al/27Al corresponds to the time (after CAI formation) when cold accretion of the parent body would have occurred, assuming 26Al/27Al throughout the solar system began with the canonical value of 5.2 × 10−5. In cases of iron meteorite parent bodies, achondrite parent bodies, and carbonaceous chondrite parent bodies, we use published isotopic ages of events (such as core formation, magma crystallization, and growth of secondary minerals) in each body's history to obtain the probable time of accretion. We find that ε54Cr correlates with accretion age: the oldest accretion ages (1 ± 0.5 Ma) are for iron and certain other differentiated meteorites with ε54Cr of −0.75 ± 0.5, and the youngest ages (3.5 ± 0.5 Ma) are for hydrated carbonaceous chondrites with ε54Cr values of 1.5 ± 0.5. Despite some outliers (notably Northwest Africa [NWA] 011 and Tafassasset), we feel that the correlation is significant and we suggest that it resulted from late, localized injection of dust with extremely high ε54Cr.
The Bow City structure, southern Alberta, Canada: The deep roots of a complex impact structure?
Authors: Glombick Paul , Schmitt Douglas R. , Xie Wei , Bown Todd , Hathway Ben , Banks Christopher
Published: April 2014

Geological and geophysical evidence is presented for a newly discovered, probable remnant complex impact structure. The structure, located near Bow City, southern Alberta, has no obvious morphological expression at surface. The geometry of the structure in the shallow subsurface, mapped using downhole geophysical well logs, is a semicircular structural depression approximately 8 km in diameter with a semicircular uplifted central region. Detailed subsurface mapping revealed evidence of localized duplication of stratigraphic section in the central uplift area and omission of strata within the surrounding annular region. Field mapping of outcrop confirmed an inlier of older rocks present within the center of the structure. Evidence of deformation along the eastern margin of the central uplift includes thrust faulting, folding, and steeply dipping bedding. Normal faults were mapped along the northern margin of the annular region. Isopach maps reveal that structural thickening and thinning were accommodated primarily within the Belly River Group. Evidence from legacy 2‐D seismic data is consistent with the subsurface mapping and reveals additional insight into the geometry of the structure, including a series of listric normal faults in the annular region and complex faulting within the central uplift. The absence of any ejecta blanket, breccia, suevite, or melt sheet (based on available data) is consistent with the Bow City structure being the remnant of a deeply eroded, complex impact structure. Accordingly, the Bow City structure may provide rare access and insight into zones of deformation remaining beneath an excavated transient crater in stratified siliciclastic target rocks.
Differences in predator composition alter the direction of structure‐mediated predation risk in macrophyte communities
Authors: Farina Simone , Arthur Rohan , Pagès Jordi F. , Prado Patricia , Romero Javier , Vergés Adriana , Hyndes Glenn , Heck Ken L. , Glenos Sybil , Alcoverro Teresa
Published: April 2014

Structural complexity strongly influences the outcome of predator–prey interactions in benthic marine communities affecting both prey concealment and predator hunting efficacy. How habitat structure interacts with species‐specific differences in predatory style and antipredatory strategies may therefore be critical in determining higher trophic functions. We examined the role of structural complexity in mediating predator–prey interactions across several macrophyte habitats along a gradient of structural complexity in three different bioregions: western Mediterranean Sea (WMS), eastern Indian Ocean (EIO) and northern Gulf of Mexico (NGM). Using sea urchins as model prey, we measured survival rates of small (juveniles) and medium (young adults) size classes in different habitat zones: within the macrophyte habitat, along the edge and in bare sandy spaces. At each site we also measured structural variables and predator abundance. Generalised linear models identified biomass and predatory fish abundance as the main determinants of predation intensity but the efficiency of predation was also influenced by urchin size class. Interestingly though, the direction of structure‐mediated effects on predation risk was markedly different between habitats and bioregions. In WMS and NGM, where predation by roving fish was relatively high, structure served as a critical prey refuge, particularly for juvenile urchins. In contrast, in EIO, where roving fish predation was low, predation was generally higher inside structurally complex environments where sea stars were responsible for much of the predation. Larger prey were generally less affected by predation in all habitats, probably due to the absence of large predators. Overall, our results indicate that, while the structural complexity of habitats is critical in mediating predator–prey interactions, the direction of this mediation is strongly influenced by differences in predator composition. Whether the regional pool of predators is dominated by visual roving species or chemotactic benthic predators may determine if structure dampens or enhances the influence of top–down control in marine macrophyte communities.
Cortical atrophy, reduced integrity of white matter and cognitive impairment in subcortical vascular dementia of Binswanger type
Authors: Jung Won‐Beom , Mun Chi‐Woong , Kim Young‐Hoon , Park Je Min , Lee Byung Dae , Lee Young Min , Moon Eunsoo , Jeong Hee Jeong , Chung Young In
Published: April 2014

Aims

An association between white matter hyperintensities (WMH) and cognitive dysfunction has long been recognized. However, subjects with identically appearing WMH on magnetic resonance imaging present with a wide variance in cognitive function ranging from normal cognition to dementia. The aim of this study was to compare cortical atrophy and integrity of white matter of patients with subcortical vascular dementia of Binswanger type (SVaD‐BT) with those of the normal cognition group with WMH (ncWMH).

Methods

Eleven patients with SVaD‐BT and 11 age‐, sex‐, education‐ and grade of WMH‐matched ncWMH underwent magnetic resonance imaging, including 3‐D volumetric images for cortical atrophy and diffusion tensor imaging for integrity of white matter.

Results

Compared to ncWMH, SVaD‐BT patients showed cortical atrophies in frontal (i.e. frontal pole, precentral gyrus and frontal medial cortex) and occipital areas (i.e. lingual gyrus) followed by atrophies in temporal (i.e. fusiform cortex and middle temporal gyrus) areas. Along with cortical atrophies, reduced integrity with low fractional anisotropy and high mean diffusivity values in genu and splenium of the corpus callosum were detected in SVaD‐BT patients.

Conclusions

Our findings suggest that cognitive decline from ncWMH to SVaD‐BT may be associated with cortical atrophy and reduced integrity of white matter.
The COMT Val158Met polymorphism regulates the effect of a dopamine antagonist on the feedback‐related negativity
Authors: Mueller Erik M. , Burgdorf Christin , Chavanon Mira‐Lynn , Schweiger Desiree , Hennig Jürgen , Wacker Jan , Stemmler Gerhard
Published: April 2014

Consistent with dopamine accounts of internal and external feedback processing, prior work showed that the dopamine D2 receptor antagonist sulpiride modulates the relationship between the dopaminergic COMT Val158Met polymorphism and the error‐related negativity (ERN). Here, we tested in an independent sample whether this Gene × Substance interaction generalizes to the feedback‐related negativity (FRN), which presumably shares underlying dopaminergic mechanisms with the ERN. N = 83 female participants genotyped for COMT Val158Met received 200 mg sulpiride versus placebo and performed a virtual ball‐catching task. The FRN to positive versus negative feedback was modulated by a significant COMT × Substance interaction. Mirroring prior work on the ERN, the tendency of the FRN to be more pronounced for VAL+ versus MET/MET carriers after placebo was reversed by sulpiride. The findings thus provide new evidence for dopaminergic models of feedback processing.
Support and continuity during the first 2 weeks postpartum
Authors: Barimani Mia , Oxelmark Lena , Johansson Sven‐Erik , Hylander Ingrid
Published: April 2014

Objectives

To investigate mothers’ perceived satisfaction with support from antenatal care (AC), postpartum care (PC) and child health care (CHC), respectively, during the first two weeks after childbirth.

Design

Cross‐sectional survey, mixed‐method design.

Ethical issues

The study was approved by the Regional Research and Ethics Committee at the Karolinska Insititutet, Sweden.

Methods

Data were collected using a study‐specific questionnaire that focused on mothers’ satisfaction with support from AC, PC and CHC during the first 2 weeks after childbirth. All mothers in Stockholm County (n = 546) who gave birth to a live infant during a 1‐week period in 2009 were invited to participate. Descriptive and logistic regression analyses and a content analysis were performed.

Results

A large discrepancy was found between levels of satisfaction with AC, PC and CHC. Mothers were satisfied with the support from CHC healthcare nurses, but missed follow‐up contact from AC and PC midwives. Nearly 40% of all mothers commented on insufficient support including that continuity in the chain of care was lacking and support for mothers’ physical and emotional health was insufficient. Delivery at <37 weeks of gestation was associated with reduced satisfaction with both AC and CHC, but not with PC. Mothers who made emergency visits during the first two weeks were more likely to be dissatisfied with support from PC.

Conclusion

All links in the chain of care are important for the support of mothers during the first 2 weeks after childbirth, but continuity needs to be improved to raise the quality of care for mothers.
Children's Observed Interactions With Best Friends: Associations With Friendship Jealousy and Satisfaction
Authors: Deutz Marike H. F. , Lansu Tessa A. M. , Cillessen Antonius H. N.
Published: April 2014

This study examined the role of friendship jealousy and satisfaction in nine‐year‐old children's observed interactions with their best friends. One hundred five dyads (51 female, 54 male) participated in a 30‐min closed‐field observational setting and reported their jealousy and satisfaction within the friendship. The Actor–Partner Interdependence Model was used to estimate the effects of friendship jealousy and satisfaction on children's own and their friends' behavior. Friends were highly similar in observed behavior and friendship characteristics. Many observed dyadic behaviors were associated with overall levels of jealousy within the friendship, but differences in friendship satisfaction were only predictive of conflict resolution in boys. Children's reports of their friendship jealousy were strongly related to their own behavior in the dyad and the behavior of their best friends. Gender differences were discussed. The results further illustrate the importance of a dyadic perspective on friendship interaction.
Sugarcane genome sequencing by methylation filtration provides tools for genomic research in the genus Saccharum
Authors: Grativol Clícia , Regulski Michael , Bertalan Marcelo , McCombie W. Richard , da Silva Felipe Rodrigues , Zerlotini Neto Adhemar , Vicentini Renato , Farinelli Laurent , Hemerly Adriana Silva , Martienssen Robert A. , Ferreira Paulo Cavalcanti Gomes
Published: April 2014

Many economically important crops have large and complex genomes that hamper their sequencing by standard methods such as whole genome shotgun (WGS). Large tracts of methylated repeats occur in plant genomes that are interspersed by hypomethylated gene‐rich regions. Gene‐enrichment strategies based on methylation profiles offer an alternative to sequencing repetitive genomes. Here, we have applied methyl filtration with McrBC endonuclease digestion to enrich for euchromatic regions in the sugarcane genome. To verify the efficiency of methylation filtration and the assembly quality of sequences submitted to gene‐enrichment strategy, we have compared assemblies using methyl‐filtered (MF) and unfiltered (UF) libraries. The use of methy filtration allowed a better assembly by filtering out 35% of the sugarcane genome and by producing 1.5× more scaffolds and 1.7× more assembled Mb in length compared with unfiltered dataset. The coverage of sorghum coding sequences (CDS) by MF scaffolds was at least 36% higher than by the use of UF scaffolds. Using MF technology, we increased by 134× the coverage of gene regions of the monoploid sugarcane genome. The MF reads assembled into scaffolds that covered all genes of the sugarcane bacterial artificial chromosomes (BACs), 97.2% of sugarcane expressed sequence tags (ESTs), 92.7% of sugarcane RNA‐seq reads and 98.4% of sorghum protein sequences. Analysis of MF scaffolds from encoded enzymes of the sucrose/starch pathway discovered 291 single‐nucleotide polymorphisms (SNPs) in the wild sugarcane species, S. spontaneum and S. officinarum. A large number of microRNA genes was also identified in the MF scaffolds. The information achieved by the MF dataset provides a valuable tool for genomic research in the genus Saccharum and for improvement of sugarcane as a biofuel crop.
Staying Home or Moving Away? Restructuring Efforts within Multinational Enterprises
Authors: Abraham Filip , Goesaert Tim , Konings Jozef
Published: April 2014

This paper analyses the impact of geographic dispersion on employment changes within multinationals. Building on earlier work of Landier et al. (2009, Review of Financial Studies 22, 3: 1119), we investigate whether corporate decision‐making within a multinational is affected by the distance between an affiliate and its headquarter. Our findings suggest a detrimental impact of distance on employees, by either an increased likelihood of observing a downsizing event, or by witnessing a larger decrease in the number of employees at distant locations during downsizing events. In addition, our results seem to relate the higher likelihood of observing a downsizing event to the role of social factors on decision making. The more visible a manager is in his community, the less likely he is to downsize proximate divisions.
A New Analytical Approach for Dynamic Modeling of Passive Multicomponent Cooling Systems
Authors: Gholami A. , Ahmadi M. , Bahrami M.
Published: April 2014

A new one-dimensional thermal network modeling approach is proposed that can accurately predict transient/dynamic temperature distribution of passive cooling systems. The present model has applications in variety of electronic, power electronic, photonics, and telecom systems, especially where the system load fluctuates over time. The main components of a cooling system including: heat spreaders, heat pipes, and heat sinks as well as thermal boundary conditions such as natural convection and radiation heat transfer are analyzed, analytically modeled and presented in the form of resistance and capacitance (RC) network blocks. The present model is capable of predicting the transient/dynamic (and steady state) thermal behavior of cooling system with significantly less cost of modeling compared to conventional numerical simulations. Furthermore, the present method takes into account system “thermal inertia” and is capable of capturing thermal lags in various components. The model is presented in two forms: zero-dimensional and one-dimensional which are different in terms of complicacy. A custom-designed test-bed is also built and a comprehensive experimental study is conducted to validate the proposed model. The experimental results show great agreement, less than 4.5% relative difference in comparison with the modeling results.
Predictive Modeling and Uncertainty Quantification of Laser Shock Processing by Bayesian Gaussian Processes With Multiple Outputs
Authors: Hu Yongxiang , Li Zhi , Li Kangmei , Yao Zhenqiang
Published: April 2014

Accurate numerical modeling of laser shock processing, a typical complex physical process, is very difficult because several input parameters in the model are uncertain in a range. And numerical simulation of this high dynamic process is very computational expensive. The Bayesian Gaussian process method dealing with multivariate output is introduced to overcome these difficulties by constructing a predictive model. Experiments are performed to collect the physical data of shock indentation profiles by varying laser power densities and spot sizes. A two-dimensional finite element model combined with an analytical shock pressure model is constructed to obtain the data from numerical simulation. By combining observations from experiments and numerical simulation of laser shock process, Bayesian inference for the Gaussian model is completed by sampling from the posterior distribution using Morkov chain Monte Carlo. Sensitivities of input parameters are analyzed by the hyperparameters of Gaussian process model to understand their relative importance. The calibration of uncertain parameters is provided with posterior distributions to obtain concentration of values. The constructed predictive model can be computed efficiently to provide an accurate prediction with uncertainty quantification for indentation profile by comparing with experimental data.
Propagation of Longitudinal Deformation Wave Along a Hoisting Rope Carrying an Intermediate Concentrated Load
Authors: Razdolsky A. G.
Published: April 2014

Motion of the hoisting rope carrying an intermediate concentrated load is described by the one-dimensional wave equation in the region consisting of two sections separated by a moving boundary condition. The system is moved by the driving force acting at the upper cross section of the rope. Position of the intermediate load and consequently the lengths of the rope sections vary in the time depending on the magnitude of driving force. Solution of the wave equation is represented as a sum of integrals with variable limits of integration. The problem is reduced to solving the sequence of ordinary differential equations which describe a motion of the load in the fixed coordinate system and the paths of the rope ends in the moving coordinate system connected with the load. The argument of functions involved in the right-hand side of these equations lag behind the argument of the derivatives in the left-hand side of equations by a short time interval. A description of the unknown functions in a parametric form makes possible to eliminate retarded arguments from the equations. The problem is solved by using a technique of the sequential continuation of solution for time intervals corresponding to propagation of the deformation wave in the opposite directions. A computer program has been developed for solving the problem. Results of the numerical solution are presented in the case that the driving force is a piecewise linear function of time and is discontinuous at the peak point.
Study on Capillary Instability With Heat and Mass Transfer Through Porous Media: Effect of Irrotational Viscous Pressure
Authors: Kumar Awasthi Mukesh
Published: April 2014

In this paper, we investigate the effect of irrotational, viscous pressure on capillary instability of the interface between two viscous, incompressible, and thermally conducting fluids in a fully saturated porous medium when the phases are enclosed between two horizontal cylindrical surfaces coaxial with the interface and when there is mass and heat transfer across the interface. The analysis extends our earlier work in which the capillary instability of two viscous and thermally conducting fluids in a fully saturated porous medium was studied assuming that the motion and pressure are irrotational and the viscosity enters through the jump in the viscous normal stress in the normal stress balance at the interface. Here, we use another irrotational theory in which the discontinuities in the irrotational tangential velocity and shear stress are eliminated in the global energy balance by taking viscous contributions to the irrotational pressure. We use the Darcy's model, and a quadratic dispersion relation is obtained. It is observed that heat and mass transfer has a stabilizing effect on the stability of the system and this effect enhances in the presence of irrotational viscous pressure.
Dynamic Analysis of Spiral-Groove Rotary Seal Ring for Wet Clutches
Authors: Zhao Yi M. , Hu Ji B. , Wei Chao
Published: April 2014

A tribo-dynamic model of a spiral-groove rotary seal ring is developed through coupling lubrication and dynamic equations. Effects of centrifugation, hydrodynamics, cavitation, and asperity contact are considered. To represent real rough surfaces, asperity contact is described by a statistics-based model. A global time marching scheme is developed to obtain the motion of seal ring and key parameters such as bearing force, friction torque, and leakage rate. Dynamic behaviors and seal characteristics of spiral-groove rotary seal ring under real and step change oil filling conditions are analyzed. The result shows that the rotary seal ring operates steadily under real conditions and has fast and stable step response. It is also indicated that the seal ring can achieve full film lubrication under high speed conditions through the oil filling and dispersing stage. The steady lubrication performance is experimentally validated.
The DEAH-Box RNA Helicase DHX15 Activates NF-κB and MAPK Signaling Downstream of MAVS During Antiviral Responses
Authors: Mosallanejad Kenta , Sekine Yusuke , Ishikura-Kinoshita Seiko , Kumagai Kazuo , Nagano Tetsuo , Matsuzawa Atsushi , Takeda Kohsuke , Naguro Isao , Ichijo Hidenori
Published: April 2014

Different RNA helicases mediate distinct responses in cells infected with RNA viruses.
Screening of Odor-Receptor Pairs in
Caenorhabditis elegans
Reveals Different Receptors for High and Low Odor Concentrations
Authors: Taniguchi Gun , Uozumi Takayuki , Kiriyama Keisuke , Kamizaki Tomoko , Hirotsu Takaaki
Published: April 2014

Distinct receptors and neuronal circuits enable worms to move toward low and away from high concentrations of the same chemical.
Ironing Out Macrophages
Authors: VanHook Annalisa M.
Published: April 2014

Although hypoferremia inhibits the growth of extracellular bacteria, it stimulates the growth of the intracellular pathogen
Salmonella
.
Stiff Path to Malignancy
Authors: Ferrarelli Leslie K.
Published: April 2014

Stiffening in the extracellular matrix inhibits the abundance of tumor suppressor PTEN in breast epithelial cells.
Cycling Akt Activity
Authors: Gough Nancy R.
Published: April 2014

Phosphorylation at C-terminal sites contributes to the increases in Akt activity associated with the cell cycle, growth factor signaling, and DNA damage.
Modifying Mitochondrial Metabolism
Authors: Berndt Jason D.
Published: April 2014

Glutarylation of lysine residues occurs in proteins involved in cellular metabolism and is regulated by diet.
Potent Neutralization of MERS-CoV by Human Neutralizing Monoclonal Antibodies to the Viral Spike Glycoprotein
Authors: Jiang Liwei , Wang Nianshuang , Zuo Teng , Shi Xuanling , Poon Kwok-Man Vincent , Wu Yongkang , Gao Fei , Li Danyang , Wang Ruoke , Guo Jianying , Fu Lili , Yuen Kwok-Yung , Zheng Bo-Jian , Wang Xinquan , Zhang Linqi
Published: April 2014

Human neutralizing monoclonal antibody could serve as a therapeutic intervention against MERS-CoV infection.
Metabolic Compensation of Fitness Costs Associated with Overexpression of the Multidrug Efflux Pump MexEF-OprN in Pseudomonas aeruginosa
Authors: Olivares Jorge , Álvarez-Ortega Carolina , Martinez José Luis
Published: April 2014

The acquisition of antibiotic resistance has been associated with a possible nonspecific, metabolic burden that is reflected in decreased fitness among resistant bacteria. We have recently demonstrated that overexpression of the MexEF-OprN multidrug efflux pump does not produce a metabolic burden when measured by classical competitions tests but rather leads to a number of changes in the organism's physiology. One of these changes is the untimely activation of the nitrate respiratory chain under aerobic conditions. MexEF-OprN is a proton/substrate antiporter. Overexpression of this element should result in a constant influx of protons, which may lead to cytoplasmic acidification. Acidification was not observed in aerobiosis, a situation in which the MexEF-overproducing mutant increases oxygen consumption. This enhanced oxygen uptake serves to eliminate intracellular proton accumulation, preventing the cytoplasmic acidification that was observed exclusively under anaerobic conditions, a situation in which the fitness of the MexEF-OprN-overproducing mutant decreases. Finally, we determined that the early activation of the nitrate respiratory chain under aerobic conditions plays a role in preventing a deleterious effect associated with the overexpression of MexEF-OprN. Our results show that metabolic rewiring may assist in overcoming the potential fitness cost associated with the acquisition of antibiotic resistance. Furthermore, the capability to metabolically compensate for this effect is habitat dependent, as demonstrated by our results under anaerobic conditions. The development of drugs that prevent metabolic compensation of fitness costs may help to reduce the persistence and dissemination of antibiotic resistance.
Crystal Structure of Mox-1, a Unique Plasmid-Mediated Class C β-Lactamase with Hydrolytic Activity towards Moxalactam
Authors: Oguri Takuma , Furuyama Takamitsu , Okuno Takashi , Ishii Yoshikazu , Tateda Kazuhiro , Bonomo Robert A. , Shimizu-Ibuka Akiko
Published: April 2014

Mox-1 is a unique plasmid-mediated class C β-lactamase that hydrolyzes penicillins, cephalothin, and the expanded-spectrum cephalosporins cefepime and moxalactam. In order to understand the unique substrate profile of this enzyme, we determined the X-ray crystallographic structure of Mox-1 β-lactamase at a 1.5-Å resolution. The overall structure of Mox-1 β-lactamase resembles that of other AmpC enzymes, with some notable exceptions. First, comparison with other enzymes whose structures have been solved reveals significant differences in the composition of amino acids that make up the hydrogen-bonding network and the position of structural elements in the substrate-binding cavity. Second, the main-chain electron density is not observed in two regions, one containing amino acid residues 214 to 216 positioned in the Ω loop and the other in the N terminus of the B3 β-strand corresponding to amino acid residues 303 to 306. The last two observations suggest that there is significant structural flexibility of these regions, a property which may impact the recognition and binding of substrates in Mox-1. These important differences allow us to propose that the binding of moxalactam in Mox-1 is facilitated by the avoidance of steric clashes, indicating that a substrate-induced conformational change underlies the basis of the hydrolytic profile of Mox-1 β-lactamase.
Inhibitor-Resistant TEM- and OXA-1-Producing Escherichia coli Isolates Resistant to Amoxicillin-Clavulanate Are More Clonal and Possess Lower Virulence Gene Content than Susceptible Clinical Isolates
Authors: Oteo Jesús , González-López Juan José , Ortega Adriana , Quintero-Zárate J. Natalia , Bou Germán , Cercenado Emilia , Conejo María Carmen , Martínez-Martínez Luis , Navarro Ferran , Oliver Antonio , Bartolomé Rosa M. , Campos José
Published: April 2014

In a previous prospective multicenter study in Spain, we found that OXA-1 and inhibitor-resistant TEM (IRT) β-lactamases constitute the most common plasmid-borne mechanisms of genuine amoxicillin-clavulanate (AMC) resistance in
Escherichia coli
. In the present study, we investigated the population structure and virulence traits of clinical AMC-resistant
E. coli
strains expressing OXA-1 or IRT and compared these traits to those in a control group of clinical AMC-susceptible
E. coli
isolates. All OXA-1-producing (
n
= 67) and IRT-producing (
n
= 45) isolates were matched by geographical and temporal origin to the AMC-susceptible control set (
n
= 56). We performed multilocus sequence typing and phylogenetic group characterization for each isolate and then studied the isolates for the presence of 49 virulence factors (VFs) by PCR and sequencing. The most prevalent clone detected was distinct for each group: group C isolates of sequence type (ST) 88 (C/ST88) were the most common in OXA-1 producers, B2/ST131 isolates were the most common in IRT producers, and B2/ST73 isolates were the most common in AMC-susceptible isolates. The median numbers of isolates per ST were 3.72 in OXA-1 producers, 2.04 in IRT producers, and 1.69 in AMC-susceptible isolates; the proportions of STs represented by one unique isolate in each group were 19.4%, 31.1%, and 48.2%, respectively. The sum of all VFs detected, calculated as a virulence score, was significantly higher in AMC-susceptible isolates than OXA-1 and IRT producers (means, 12.5 versus 8.3 and 8.2, respectively). Our findings suggest that IRT- and OXA-1-producing
E. coli
isolates resistant to AMC have a different and less diverse population structure than AMC-susceptible clinical
E. coli
isolates. The AMC-susceptible population also contains more VFs than AMC-resistant isolates.
Epithelial Microvilli Establish an Electrostatic Barrier to Microbial Adhesion
Authors: Bennett Kaila M. , Walker Sharon L. , Lo David D.
Published: April 2014

Microvilli are membrane extensions on the apical surface of polarized epithelia, such as intestinal enterocytes and tubule and duct epithelia. One notable exception in mucosal epithelia is M cells, which are specialized for capturing luminal microbial particles; M cells display a unique apical membrane lacking microvilli. Based on studies of M cell uptake under different ionic conditions, we hypothesized that microvilli may augment the mucosal barrier by providing an increased surface charge density from the increased membrane surface and associated glycoproteins. Thus, electrostatic charges may repel microbes from epithelial cells bearing microvilli, while M cells are more susceptible to microbial adhesion. To test the role of microvilli in bacterial adhesion and uptake, we developed polarized intestinal epithelial cells with reduced microvilli (“microvillus-minus,” or MVM) but retaining normal tight junctions. When tested for interactions with microbial particles in suspension, MVM cells showed greatly enhanced adhesion and uptake of particles compared to microvillus-positive cells. This preference showed a linear relationship to bacterial surface charge, suggesting that microvilli resist binding of microbes by using electrostatic repulsion. Moreover, this predicts that pathogen modification of electrostatic forces may contribute directly to virulence. Accordingly, the effacement effector protein Tir from enterohemorrhagic
Escherichia coli
O157:H7 expressed in epithelial cells induced a loss of microvilli with consequent enhanced microbial binding. These results provide a new context for microvillus function in the host-pathogen relationship, based on electrostatic interactions.
Characterization of Immunological Cross-Reactivity between Enterotoxigenic Escherichia coli Heat-Stable Toxin and Human Guanylin and Uroguanylin
Authors: Taxt Arne M. , Diaz Yuleima , Bacle Amélie , Grauffel Cédric , Reuter Nathalie , Aasland Rein , Sommerfelt Halvor , Puntervoll Pål
Published: April 2014

Enterotoxigenic
Escherichia coli
(ETEC) expressing the heat-stable toxin (ST) (human-type [STh] and porcine-type [STp] variants) is among the five most important enteric pathogens in young children living in low- and middle-income countries. ST mediates diarrheal disease through activation of the guanylate cyclase C (GC-C) receptor and is an attractive vaccine target with the potential to confer protection against a wide range of ETEC strains. However, immunological cross-reactivity to the endogenous GC-C ligands guanylin and uroguanylin is a major concern because of the similarities to ST in amino acid sequence, structure, and function. We have investigated the presence of similar epitopes on STh, STp, guanylin, and uroguanylin by analyzing these peptides in eight distinct competitive enzyme-linked immunosorbent assays (ELISAs). A fraction (27%) of a polyclonal anti-STh antibody and an anti-STh monoclonal antibody (MAb) cross-reacted with uroguanylin, the latter with a 73-fold-lower affinity. In contrast, none of the antibodies raised against STp, one polyclonal antibody and three MAbs, cross-reacted with the endogenous peptides. Antibodies raised against guanylin and uroguanylin showed partial cross-reactivity with the ST peptides. Our results demonstrate, for the first time, that immunological cross-reactions between ST and the endogenous peptides can occur. However, the partial nature and low affinity of the observed cross-reactions suggest that the risk of adverse effects from a future ST vaccine may be low. Furthermore, our results suggest that this risk may be reduced or eliminated by basing an ST immunogen on STp or a selectively mutated variant of STh.
Origins of a 350-Kilobase Genomic Duplication in Mycobacterium tuberculosis and Its Impact on Virulence
Authors: Domenech Pilar , Rog Anya , Moolji Jalal-ud-din , Radomski Nicolas , Fallow Ashley , Leon-Solis Lizbel , Bowes Julia , Behr Marcel A. , Reed Michael B.
Published: April 2014

In the present study, we have investigated the evolution and impact on virulence of a 350-kb genomic duplication present in the most recently evolved members of theMycobacterium tuberculosisEast Asian lineage. In a mouse model of infection, comparing HN878 subclones HN878-27 (no duplication) and HN878-45 (with the 350-kb duplication) revealed that the latter is impaired forin vivogrowth during the initial 3 weeks of infection. Furthermore, the median survival time of mice infected with isolate HN878-45 is significantly longer (77 days) than that of mice infected with HN878-27. Whole-genome sequencing of both isolates failed to reveal any mutational events other than the duplication that could account for such a substantial difference in virulence. Although we and others had previously speculated that the 350-kb duplication arose in response to some form of host-applied selective pressure (P. Domenech, G. S. Kolly, L. Leon-Solis, A. Fallow, M. B. Reed, J. Bacteriol.192:4562–4570, 2010, and B. Weiner, J. Gomez, T. C. Victor, R. M. Warren, A. Sloutsky, B. B. Plikaytis, J. E. Posey, P. D. van Helden, N. C. Gey van Pittius, M. Koehrsen, P. Sisk, C. Stolte, J. White, S. Gagneux, B. Birren, D. Hung, M. Murray, J. Galagan, PLoS One7:e26038, 2012), here we show that this large chromosomal amplification event is very rapidly selected within standardin vitrobroth cultures in a range of isolates. Indeed, subclones harboring the duplication were detectable after just five rounds ofin vitropassage. In contrast, the duplication appears to be highly unstablein vivoand is negatively selected during the later stages of infection in mice. We believe that the rapidin vitroevolution ofM. tuberculosisis an underappreciated aspect of its biology that is often ignored, despite the fact that it has the potential to confound the data and conclusions arising from comparative studies of isolates at both the genotypic and phenotypic levels.
Night blindness due to vitamin A deficiency associated with copper deficiency myelopathy secondary to bowel bypass surgery
Authors: Abdul Jabbar AlHassany Ali
Published: April 2014

We present an interesting case of combined vitamin A and copper deficiency after a history of gastric bypass surgery where symptoms improved after parenteral copper and vitamin A treatment. Gastric bypass surgery as a cause of fat soluble vitamin deficiency is generally under-reported. Copper deficiency has been reported after gastric bypass surgery. Vitamin A deficiency after gastric bypass surgery has also been reported in the literature, but the reported cases again fall below the actual figures. B12and folate deficiencies can produce a type of myelopathy similar to that produced by copper deficiency, and differentiation on the basis of laboratory tests, neurophysiology and improvement of symptoms after replacement therapy might be the hallmark of diagnosis. Combinations of vitamin deficiencies were previously reported, but no cases of combined vitamin A and copper deficiency could be found in the literature.
Haemoptysis or haematemesis? The not so bleeding obvious
Authors: Baumer Thomas Edward
Published: April 2014

An aortobronchial fistula is a rare but important diagnosis, which if missed is potentially fatal. We describe a case of a man who presented with severe, spontaneous per oral bleeding. The patient believed the bleeding occurred on coughing not vomiting. Despite denying haematemesis, initial investigations were focused on excluding an upper gastrointestinal bleed because of multiple risk factors (previous alcohol dependence, recent gastritis and heavy smoking). Two urgent oesophagogastroduodenoscopys were unremarkable. A plain chest film demonstrated left-sided perihilar shadowing of possible neoplastic origin. Two days later following sudden torrential haemoptysis, an emergency CT angiogram demonstrated a descending aortic aneurysm and associated aorto-bronchial fistula. The case helps reaffirm the old aphorism that “the patient is telling you the diagnosis”— this was indeed haemoptysis not haematemesis. Despite the power of hindsight, it is a reminder that accurate history-taking is essential in selecting the best first-line investigation, particularly in cases of diagnostic uncertainty.
A retrospective cohort study identifying the principal pathological features useful in the diagnosis of inclusion body myositis
Authors: Brady Stefen , Squier Waney , Sewry Caroline , Hanna Michael , Hilton-Jones David , Holton Janice L
Published: April 2014

Objective

The current pathological diagnostic criteria for sporadic inclusion body myositis (IBM) lack sensitivity. Using immunohistochemical techniques abnormal protein aggregates have been identified in IBM, including some associated with neurodegenerative disorders. Our objective was to investigate the diagnostic utility of a number of markers of protein aggregates together with mitochondrial and inflammatory changes in IBM.

Design

Retrospective cohort study. The sensitivity of pathological features was evaluated in cases of Griggs definite IBM. The diagnostic potential of the most reliable features was then assessed in clinically typical IBM with rimmed vacuoles (n=15), clinically typical IBM without rimmed vacuoles (n=9) and IBM mimics—protein accumulation myopathies containing rimmed vacuoles (n=7) and steroid-responsive inflammatory myopathies (n=11).

Setting

Specialist muscle services at the John Radcliffe Hospital, Oxford and the National Hospital for Neurology and Neurosurgery, London.

Results

Individual pathological features, in isolation, lacked sensitivity and specificity. However, the morphology and distribution of p62 aggregates in IBM were characteristic and in a myopathy with rimmed vacuoles, the combination of characteristic p62 aggregates and increased sarcolemmal and internal major histocompatibility complex class I expression or endomysial T cells were diagnostic for IBM with a sensitivity of 93% and specificity of 100%. In an inflammatory myopathy lacking rimmed vacuoles, the presence of mitochondrial changes was 100% sensitive and 73% specific for IBM; characteristic p62 aggregates were specific (91%), but lacked sensitivity (44%).

Conclusions

We propose an easily applied diagnostic algorithm for the pathological diagnosis of IBM. Additionally our findings support the hypothesis that many of the pathological features considered typical of IBM develop later in the disease, explaining their poor sensitivity at disease presentation and emphasising the need for revised pathological criteria to supplement the clinical criteria in the diagnosis of IBM.
Development of evidence-based Australian medication-related indicators of potentially preventable hospitalisations: a modified RAND appropriateness method
Authors: Caughey Gillian E , Kalisch Ellett Lisa M , Wong Te Ying
Published: April 2014

Objective

Indicators of potentially preventable hospitalisations have been adopted internationally as a measure of health system performance; however, few assess appropriate processes of care around medication use, that if followed may prevent hospitalisation. The aim of this study was to develop and validate evidence-based medication-related indicators of potentially preventable hospitalisations.

Setting

Australian primary healthcare.

Participants

Medical specialists, general practitioners and pharmacists. A modified RAND appropriateness method was used for the development of medication-related indicators of potentially preventable hospitalisations, which included a literature review, assessment of the strength of the supporting evidence base, an initial face and content validity by an expert panel, followed by an independent assessment of indicators by an expert clinical panel across various disciplines, using an online survey.

Primary outcome measure

Analysis of ratings was performed on the four key elements of preventability; the medication-related problem must be recognisable, the adverse outcomes foreseeable and the causes and outcomes identifiable and controllable.

Results

A total of 48 potential indicators across all major disease groupings were developed based on level III evidence or greater, that were independently assessed by 78 expert clinicians (22.1% response rate). The expert panel considered 29 of these (60.4%) sufficiently valid. Of these, 21 (72.4%) were based on level I evidence.

Conclusions

This study provides a set of face and content validated indicators of medication-related potentially preventable hospitalisations, linking suboptimal processes of care and medication use with subsequent hospitalisation. Further analysis is required to establish operational validity in a population-based sample, using an administrative health database. Implementation of these indicators within routine monitoring of healthcare systems will highlight those conditions where hospitalisations could potentially be avoided through improved medication management.