bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanisms of in vivo muscle fatigue in humans: investigating age‐related fatigue resistance with a computational model
Authors: Callahan Damien M. , Umberger Brian R. , Kent Jane A.
Published: January 2016

Key points

Muscle fatigue can be defined as the transient decrease in maximal force that occurs in response to muscle use. Fatigue develops because of a complex set of changes within the neuromuscular system that are difficult to evaluate simultaneously in humans.

The skeletal muscle of older adults fatigues less than that of young adults during static contractions. The potential sources of this difference are multiple and intertwined.

To evaluate the individual mechanisms of fatigue, we developed an integrative computational model based on neural, biochemical, morphological and physiological properties of human skeletal muscle.

Our results indicate first that the model provides accurate predictions of fatigue and second that the age‐related resistance to fatigue is due largely to a lower reliance on glycolytic metabolism during contraction.

This model should prove useful for generating hypotheses for future experimental studies into the mechanisms of muscle fatigue.

During repeated or sustained muscle activation, force‐generating capacity becomes limited in a process referred to as fatigue. Multiple factors, including motor unit activation patterns, muscle fibre contractile properties and bioenergetic function, can impact force‐generating capacity and thus the potential to resist fatigue. Given that neuromuscular fatigue depends on interrelated factors, quantifying their independent effects on force‐generating capacity is not possible in vivo. Computational models can provide insight into complex systems in which multiple inputs determine discrete outputs. However, few computational models to date have investigated neuromuscular fatigue by incorporating the multiple levels of neuromuscular function known to impact human in vivo function. To address this limitation, we present a computational model that predicts neural activation, biomechanical forces, intracellular metabolic perturbations and, ultimately, fatigue during repeated isometric contractions. This model was compared with metabolic and contractile responses to repeated activation using values reported in the literature. Once validated in this way, the model was modified to reflect age‐related changes in neuromuscular function. Comparisons between initial and age‐modified simulations indicated that the age‐modified model predicted less fatigue during repeated isometric contractions, consistent with reports in the literature. Together, our simulations suggest that reduced glycolytic flux is the greatest contributor to the phenomenon of age‐related fatigue resistance. In contrast, oxidative resynthesis of phosphocreatine between intermittent contractions and inherent buffering capacity had minimal impact on predicted fatigue during isometric contractions. The insights gained from these simulations cannot be achieved through traditional in vivo or in vitro experimentation alone.
Repair versus shaving of partial-thickness articular-sided tears of the upper subscapularis tendon. A prospective randomized controlled trial
Authors: Randelli Pietro , Arrigoni Paolo , Aliprandi Alberto , Sdao Silvana , Ragone Vincenza , D’Ambrosi Riccardo , Randelli Filippo , Cabitza Paolo , Banfi Giuseppe
Published: January 2016

Purpose:the purpose of this study was to evaluate whether treating partial-thickness articular-sided tears of the upper subscapularis (SSC) tendon with a dedicated suture anchor would result in an internal rotation strength improvement compared with simple shaving of the SSC tendon and footprint.

Methods: twenty-six patients with a limited SSC tendon tear (equal or inferior to the most superior centimeter) in association with a posterosuperior cuff lesion were prospectively randomized to two treatments: repair with a dedicated suture anchor versus shaving of the tendon and footprint. The patients also underwent long head of the biceps (LHB) treatment and posterosuperior cuff tear repair. In each patient the following parameters were measured both preoperatively and at a minimum follow-up of 2.5 years: strength in internal rotation in the bear-hug testing position (using a digital tensiometer), DASH score and Constant scores. MRI assessment of tendon healing was performed at the final follow-up.

Results: twenty of the 26 patients (76%) were reviewed after a mean follow-up time of 42 months: 11 patients had undergone SSC tendon repair and nine simple shaving. At final follow-up no significant differences were found between the repaired and shaving group in strength in internal rotation (9.5 ± 3.8 kg versus 10.3±5.4 kg; p=0.7). the DASH score and Constant score also failed to show significant differences between the two groups. Furthermore, no significant difference in SSC tendon healing rate was observed on MRI evaluation.

Conclusions: partial-thickness articular-sided tear of the upper SSC tendon in association with a posterosuperior rotator cuff repair and LHB treatment, when limited to the superior centimeter of the SSC tendon, shows a comparable performance in terms of strength in internal rotation either after simple shaving or a tendon-to-bone repair.

Level of evidence: Level II, prospective comparative study.
The management of chronic osteoarticular pain in the outpatient setting: results of an ASON audit
Authors: Mammucari Massimo , Gigliotti Sergio , Pucino Angelo , Capezza Maria , Santé Giuseppe ,   On Behalf of the ASON Study Group
Published: January 2016

The management of patients with chronic osteoarticular pain requires a comprehensive clinical evaluation and a multidisciplinary approach. Thirty specialists (orthopedic specialists, rheumatologists, physiatrists), members of the National Association of Osteoarticular Specialists (ASON), attended a specific training course in the use of a standardized medical record designed for the management of osteoarticular pain in outpatients. An audit on 888 medical records was later conducted and it showed that use of this instrument led to an improvement in the diagnostic-therapeutic
approach.

A complete and accurate medical record compilation process may also promote collaborative interaction among the healthcare practitioners involved and this can result in greater efficiency and continuity of care. ASON recommends expediting the use of electronic tools to facilitate information-sharing among pain care specialists. This study shows that the use of electronic tools facilitates the exchange of information between healthcare providers. ASON supports the adoption of similar instruments in order to improve the management of chronic pain.

Level of evidence: Level III, cross-sectional survey.
A Novel Method for Optical High Spatiotemporal Strain Analysis for Transcatheter Aortic Valves In Vitro
Authors: Heide-Jørgensen Simon , Kumaran Krishna Sellaswasmy , Taborsky Jonas , Bechsgaard Tommy , Zegdi Rachid , Johansen Peter
Published: January 2016

The transcatheter aortic valve implantation (TAVI) valve is a bioprosthetic valve within a metal stent frame. Like traditional surgical bioprosthetic valves, the TAVI valve leaflet tissue is expected to calcify and degrade over time. However, clinical studies of TAVI valve longevity are still limited. In order to indirectly assess the longevity of TAVI valves, an estimate of the mechanical wear and tear in terms of valvular deformation and strain of the leaflets under various conditions is warranted. The aim of this study was, therefore, to develop a platform for noncontact TAVI valve deformation analysis with both high temporal and spatial resolutions based on stereophotogrammetry and digital image correlation (DIC). A left-heart pulsatile in vitro flow loop system for mounting of TAVI valves was designed. The system enabled high-resolution imaging of all three TAVI valve leaflets simultaneously for up to 2000 frames per second through two high-speed cameras allowing three-dimensional analyses. A coating technique for applying a stochastic pattern on the leaflets of the TAVI valve was developed. The technique allowed a pattern recognition software to apply frame-by-frame cross correlation based deformation measurements from which the leaflet motions and the strain fields were derived. The spatiotemporal development of a very detailed strain field was obtained with a 0.5 ms time resolution and a spatial resolution of 72 μm/pixel. Hence, a platform offering a new and enhanced supplementary experimental evaluation of tissue valves during various conditions in vitro is presented.
The Heat Transfer Characteristics of Rolling Wheel and the Characteristic Length Determining Them
Authors: Wang Liangbi , Zhang Yongheng , Wu Yuan , Wang Qiuwang , Yin Zhihui
Published: January 2016

The convective heat transfer characteristics on the surface of a rolling wheel are investigated using the naphthalene sublimation technique. Five sizes of rolling wheel are selected in the experiments. The local and average Nusselt numbers are obtained. The results reveal that if the wheel radius is used as the characteristic length, the relationship between Nusselt number and Reynolds number is dependent on the wheel radius. This indicates that the wheel radius is not the characteristic length to determine the dimensionless convective heat transfer characteristics of the rolling wheel. Thus, a newly defined characteristic length is provided. For different radii of the wheel, the relationships between Nusselt number and Reynolds number based on this length collapse into one reasonable correlation. The correlation not only enriches the insight of convective heat transfer on rolling wheel but also extends the applicability of the present experimental data.
Combined Effects of Magnetic Field and Thermal Radiation on Fluid Flow and Heat Transfer of Mixed Convection in a Vertical Cylindrical Annulus
Authors: Li Ben-Wen , Wang Wei , Zhang Jing-Kui
Published: January 2016

Magnetohydrodynamic (MHD, also for magnetohydrodynamics) mixed convection of electrically conducting and radiative participating fluid is studied in a differentially heated vertical annulus. The outer cylinder is stationary, and the inner cylinder is rotating at a constant angular speed around its axis. The temperature difference between the two cylindrical walls creates buoyancy force, due to the density variation. A constant axial magnetic field is also imposed to resist the fluid motion. The nonlinear integro-differential equation, which characterizes the radiation transfer, is solved by the discrete ordinates method (DOM). The MHD equations, which describe the magnetic and transport phenomena, are solved by the collocation spectral method (CSM). Detailed numerical results of heat transfer rate, velocity, and temperature fields are presented for 0≤Ha≤100, 0.1≤τL≤10, 0≤ω≤1, and 0.2≤εW≤1. The computational results reveal that the fluid flow and heat transfer are effectively suppressed by the magnetic field as expected. Substantial changes occur in flow patterns as well as in isotherms, when the optical thickness and emissivity of the walls vary in the specified ranges. However, the flow structure and the temperature distribution change slightly when the scattering albedo increases from 0 to 0.5, but a substantial change is observed when it increases to 1.
Numerical Solution of Heat Conduction in a Heterogeneous Multiscale Material With Temperature-Dependent Properties
Authors: White James
Published: January 2016

Numerical solution of heat conduction in a heterogeneous material with small spatial and time scales can lead to excessive compute times due to the dense computational grids required. This problem is avoided by averaging the energy equation over the small-scales, which removes the appearance of the short spatial and time scales while retaining their effect on the average temperature. Averaging does, however, increase the complexity of the resulting thermal energy equation by introducing mixed spatial derivatives and six different averaged conductivity terms for three-dimensional analysis. There is a need for a numerical method that efficiently and accurately handles these complexities as well as the other details of the averaged thermal energy equation. That is the topic of this paper as it describes a numerical solution for the averaged thermal energy equation based on Fourier conduction reported recently in the literature. The solution, based on finite difference techniques that are second-order time-accurate and noniterative, is appropriate for three-dimensional time-dependent and steady-state analysis. Speed of solution is obtained by spatially factoring the scheme into an alternating direction sequence at each time level. Numerical stability is enhanced by implicit algorithms that make use of the properties of tightly banded matrices. While accurately accounting for the nonlinearity introduced into the energy equation by temperature-dependent properties, the numerical solution algorithm requires only the consideration of linear systems of algebraic equations in advancing the solution from one time level to the next. Computed examples are included and compared with those for a homogeneous material.
Cooling Optimization Theory—Part I: Optimum Wall Temperature, Coolant Exit Temperature, and the Effect of Wall/Film Properties on Performance
Authors: Kirollos Benjamin , Povey Thomas
Published: January 2016

Gas turbine cooling system design is constrained by a maximum allowable wall temperature (dictated by the material and the life requirements of the component), minimum coolant mass flow rate (the requirement to minimize cycle-efficiency cost), and uniform wall temperature (to reduce thermal stresses). These three design requirements form the basis of an iterative design process. The relationship between the requirements has received little discussion in the literature, despite being of interest from both a theoretical and a practical viewpoint. In this paper, we consider the optimum cooling system for parts with both internal and film cooling. We show analytically that the coolant mass flow rate is minimized when the wall temperature is uniform and equal to the maximum allowable wall temperature. Thus, we show that achieving uniform wall temperature achieves minimum coolant flow rate, and vice versa. The purpose is to clarify the interplay between two design requirements that are often discussed separately in the literature. The penalty (in terms of coolant mass flow) associated with cooling nonisothermal components is quantified. We show that a typical high pressure nozzle guide vane (HPNGV) operating isothermally at the maximum allowable wall temperature requires two-thirds the coolant of a typical nonisothermal vane. The optimum coolant exit temperature is also considered. It is shown analytically that the optimum coolant exit temperature depends on the balance between the mean adiabatic film cooling effectiveness, the nondimensional mass flow rate, and the Biot number of the thermal barrier coating (TBC). For the large majority of gas turbine cooling systems (e.g., a typical HPNGV) it is shown that the optimum coolant exit temperature is equal to the local wall temperature at the point of injection. For a small minority of systems (e.g., long effusion cooling systems operating at low mass flow rates), it is shown that the coolant exit temperature should be minimized. An approximation relating the wall/film properties, the nondimensional mass flow, and the overall cooling effectiveness is derived. It is used to estimate the effect of Biot number (TBC and metal), heat transfer coefficient (HTC) ratio, and film properties on the performance of a typical HPNGV and effusion cooling system. In Part II, we show that designs which achieve uniform wall temperature have a particular corresponding internal HTC distribution.
Soft Analyzer for Monitoring NOx Emissions From a Gas Turbine Combustor
Authors: Al-Malak Ali , Elshafei Moustafa , Habib Mohamed A. , Al-Zaharnah Iyad
Published: January 2016

Many industrial sectors built cogeneration plants to secure their power supplies reliably and to efficiently produce the plant demand of steam through the associated heat. Due to the rise of fuel cost and tightening environmental regulations, the number of cogeneration plants will increase in lieu to individual boilers and steam turbine generators. Most of the recent cogeneration plants are equipped with hardware-based analyzer which is a continuous emission monitoring system (CEMS) to monitor the NOx emissions from the plant stack as per U.S. Environmental Protection Agency (EPA) regulations. The CEMS is unreliable due to high failure rates and requires high capital cost, high maintenance cost, high operational cost in addition to being subject to long lag time and having slow response. In this work, a software-based analyzer is designed by applying artificial neural networks (ANNs) on process data collected from cogeneration plant (156 MW X 2 combustion gas turbine generators (CGTGs)) equipped with CEMS for NOx monitoring. The developed soft analyzer will be used to verify the existing CEMS readings and used as a reliable tool to monitor the NOx emissions that will eventually replace the CEMS. By providing a relationship between the process and the emissions, the soft analyzer will also assist in understanding the NOx behavior in reference to the process variations and thus enables better emission control.
Development of a Stiffness-Based Chemistry Load Balancing Scheme, and Optimization of Input/Output and Communication, to Enable Massively Parallel High-Fidelity Internal Combustion Engine Simulations
Authors: Kodavasal Janardhan , Harms Kevin , Srivastava Priyesh , Som Sibendu , Quan Shaoping , Richards Keith , García Marta
Published: January 2016

A closed-cycle gasoline compression ignition (GCI) engine simulation near top dead center (TDC) was used to profile the performance of a parallel commercial engine computational fluid dynamics (CFD) code, as it was scaled on up to 4096 cores of an IBM Blue Gene/Q (BG/Q) supercomputer. The test case has 9 × 106 cells near TDC, with a fixed mesh size of 0.15 mm, and was run on configurations ranging from 128 to 4096 cores. Profiling was done for a small duration of 0.11 crank angle degrees near TDC during ignition. Optimization of input/output (I/O) performance resulted in a significant speedup in reading restart files, and in an over 100-times speedup in writing restart files and files for postprocessing. Improvements to communication resulted in a 1400-times speedup in the mesh load balancing operation during initialization, on 4096 cores. An improved, “stiffness-based” algorithm for load balancing chemical kinetics calculations was developed, which results in an over three-times faster runtime near ignition on 4096 cores relative to the original load balancing scheme. With this improvement to load balancing, the code achieves over 78% scaling efficiency on 2048 cores, and over 65% scaling efficiency on 4096 cores, relative to 256 cores.
Mass spectrometry of oligopeptides in the presence of large amounts of alkali halides using desorption/ionization induced by neutral cluster impact
Authors: Portz André , Baur Markus , Gebhardt Christoph R. , Dürr Michael
Published: January 2016

Oligopeptides in the presence of large amounts of salt were desorbed and ionized using desorption/ionization induced by neutral clusters (DINeC) for further analysis by means of mass spectrometry (MS). Using oligopeptides in alkali halide solutions as a model system, DINeC was shown to yield clear and fragmentation free mass spectra of the biomolecules even from environments with a large excess of salt. The results were traced back to a phase separation between salt and biomolecules during sample preparation. The ratio between alkali metal complexes [M+A]+ and bare biomolecules [M+H]+ was controlled using different preparation schemes. DINeC was applied to the products of a tryptic digest of bovine serum albumin in the presence of sodium chloride; the results of a mass fingerprint analysis did not show a major difference for the spectra with and without salt in the original solution. The metal-ion/peptide interaction was further investigated by means of tandem-MS.
Matrix effects in biological SIMS using cluster ion beams of different chemical composition
Authors: Alnajeebi Afnan M. , Vickerman John C. , Lockyer Nicholas P.
Published: January 2016

The influence of the matrix effect on secondary ion yield presents a very significant challenge in quantitative secondary ion mass spectrometry (SIMS) analysis, for example, in determining the relative concentrations of metabolites that characterize normal biological activities or disease progression. Not only the sample itself but also the choice of primary ion beam may influence the extent of ionization suppression/enhancement due to the local chemical environment. In this study, an assessment of ionization matrix effects was carried out on model systems using C60+, Arn+, and (H2O)n+ cluster ion beams. The analytes are pure and binary mixtures of amino acids arginine and histidine biological standards. Ion beams of 20 keV were compared with a range of cluster sizes n = 1000–10 000. The component secondary ion yields were assessed for matrix effects using different primary ion beams and sample composition. The presence of water in the cluster beam is associated with a reduction in the observed matrix effects, suggesting that chemically reactive ion beams may provide a route to more quantitative SIMS analysis of complex biological systems.
Local propagation speed constrained estimation of the slowness vector from non-planar array observations
Authors: Nouvellet Adrien , Roueff François , Le Pichon Alexis , Charbit Maurice , Vergoz Julien , Kallel Mohamed , Mejri Chourouq
Published: January 2016

The estimation of the slowness vector of infrasound waves propagating across an array is a critical process leading to the determination of parameters of interest such as the direction of arrival. The sensors of an array are often considered to be located in a horizontal plane. However, due to topography, the altitudes of the sensors are not identical and introduce a bias on the estimate if neglected. However, the unbiased 3D estimation procedure, while suppressing the bias, leads to an increase of the variance. Accounting for an a priori constraint on the slowness vector significantly reduces the variance and could therefore improve the performance of the estimation if the introduced bias by incorrect a priori information remains negligible. This study focuses on measuring the benefits of this approach with a thorough investigation of the bias and variance of the constrained 3D estimator, which is not available in the existing literature. This contribution provides such computations based on an asymptotic Gaussian approximation. Simulations are carried out to assess the theoretical results both with synthetic and real data. Thus, a constrained 3D estimator is proposed yielding the best bias/variance compromise if good knowledge of the propagation wave speed is accessible.
Dietary antigens limit mucosal immunity by inducing regulatory T cells in the small intestine
Authors: Kim Kwang Soon , Hong Sung-Wook , Han Daehee , Yi Jaeu , Jung Jisun , Yang Bo-Gie , Lee Jun Young , Lee Minji , Surh Charles D.
Published: January 2016

Keeping immune cells quiet on a diet

Over thousands of years, our immune systems has evolved to distinguish self from foreign, perpetrating attacks on microbes but not ourselves. Given this, why do we fail to mount an immune response against most of the food we eat? Kim
et al.
compared normal mice, mice lacking microbes, and mice lacking microbes that were fed an elemental diet devoid of dietary antigens (see the Perspective by Kuhn and Weiner). Dietary antigens normally induced a population of suppressive immune cells called regulatory T cells in the small intestine. The cells were distinct from regulatory T cells induced by microbial antigens and prevented strong reactions against food.

Science
, this issue p.
858
; see also p.
810
2.3 Å resolution cryo-EM structure of human p97 and mechanism of allosteric inhibition
Authors: Banerjee Soojay , Bartesaghi Alberto , Merk Alan , Rao Prashant , Bulfer Stacie L. , Yan Yongzhao , Green Neal , Mroczkowski Barbara , Neitz R. Jeffrey , Wipf Peter , Falconieri Veronica , Deshaies Raymond J. , Milne Jacqueline L. S. , Huryn Donna , Arkin Michelle , Subramaniam Sriram
Published: January 2016

AAA ATPase conformational high jinks

The protein p97 is an AAA adenosine triphosphatase (ATPase) that uses energy from ATP hydrolysis to regulate substrates involved in intracellular protein quality control. Its role in this central process makes it a target for cancer chemotherapy. Banerjee
et al.
used cryo-electron microscopy to determine high-resolution structures for multiple conformational states of this dynamic macromolecular machine. They also determined the structure of the ADP-bound state bound to an inhibitor. The structures give insight into nucleotide-driven structural changes that drive function and show how inhibitor binding prevents these conformational changes

Science
, this issue p.
871
Genome Sequence of
Janthinobacterium
sp. CG23_2, a Violacein-Producing Isolate from an Antarctic Supraglacial Stream
Authors: Smith Heidi J. , Foreman Christine M. , Akiyama Tatsuya , Franklin Michael J. , Devitt Nicolas P. , Ramaraj Thiruvarangan
Published: January 2016

Here, we present the draft genome sequence for the violacein-producing
Janthinobacterium
sp. CG23_2 isolated from an Antarctic supraglacial stream. The genome is ~7.85 Mb, with a G+C content of 63.5%. The genome includes 7,247 candidate protein coding genes, which may provide insight into UV tolerance mechanisms.
Complete Genome Sequence of Fish Pathogen Aeromonas hydrophila JBN2301
Authors: Yang Wuming , Li Ningqiu , Li Ming , Zhang Defeng , An Guannan
Published: January 2016

Aeromonas hydrophila
is one of the most important fish pathogens in China. Here, we report complete genome sequence of a virulent strain,
A. hydrophila
JBN2301, which was isolated from diseased crucian carp.
Complete Genome Sequence of the Proteorhodopsin-Containing Marine Bacterium
Sediminicola
sp. YIK13
Authors: Kwon Yong Min , Kim Sang-Jin
Published: January 2016

Sediminicola
sp. YIK13 is a marine flavobacterium, isolated from tidal flat sediment. Here, we present the first complete genome sequence of this genus, which consists of 3,569,807 bp with 39.4% GC content. This strain contains proteorhodopsin, as well as retinal biosynthesis genes, allowing it to utilize sunlight as an energy source.
Genome Sequences of Five Arboviruses in Field-Captured Mosquitoes in a Unique Rural Environment of South Korea
Authors: Hang Jun , Klein Terry A. , Kim Heung-Chul , Yang Yu , Jima Dereje D. , Richardson Jason H. , Jarman Richard G.
Published: January 2016

Here, we present the genome sequences of one mesonivirus and four novel arboviruses observed in
Culex bitaeniorhynchus
and
Culex pipiens
, captured in and near the demilitarized zone, Republic of Korea. Results suggest the ubiquitous presence of mesoniviruses and the discovery of a potentially new species of arboviruses in field-captured mosquitoes.
Complete Genome Sequence of KPC-Producing Klebsiella pneumoniae Strain CAV1193
Authors: Sheppard Anna E. , Stoesser Nicole , Sebra Robert , Kasarskis Andrew , Deikus Gintaras , Anson Luke , Walker A. Sarah , Peto Tim E. , Crook Derrick W. , Mathers Amy J.
Published: January 2016

Carbapenem resistance in
Klebsiella pneumoniae
, frequently conferred by the
bla
KPC
gene, is a major public health threat. We sequenced a
bla
KPC
-containing strain of
K. pneumoniae
belonging to the emergent lineage ST941, in order to better understand the evolution of
bla
KPC
within this species.
Genome Sequence of Highly Virulent Pseudomonas aeruginosa Strain VA-134, Isolated from a Burn Patient
Authors: Miller Christine L. , Chen Tsute , Chen Ping , Leung Kai P.
Published: January 2016

Infection with
Pseudomonas aeruginosa
leads to impairment of healing and many deaths in severe burn patients. The phenotypic diversity of
P. aeruginosa
strains makes it difficult to define a therapeutic strategy. Here we report the genome sequence of a highly virulent strain of
P. aeruginosa
, VA-134, isolated from a burn patient.
Draft Genome Sequence of Bacillus amyloliquefaciens Strain RHNK22, Isolated from Rhizosphere with Biosurfactant (Surfactin, Iturin, and Fengycin) and Antifungal Activity
Authors: Narendra Kumar Papathoti , Swapna T. H. , Sathi Reddy Koppula , Archana K. , Nageshwar Lingampalli , Nalini S. , Khan Mohamed Yahya , Hameeda Bee
Published: January 2016

Bacillus amyloliquefaciens
strain RHNK22 isolated from groundnut rhizosphere showed direct and indirect plant growth-promoting traits along with biosurfactant activity and reduction in surface tension of water. Biosurfactants were identified as lipopeptides (surfactin, iturin, and fengycin) by molecular and biochemical analysis in our studies.
Improved Diagnosis of Prosthetic Joint Infection by Culturing Periprosthetic Tissue Specimens in Blood Culture Bottles
Authors: Peel Trisha N. , Dylla Brenda L. , Hughes John G. , Lynch David T. , Greenwood-Quaintance Kerryl E. , Cheng Allen C. , Mandrekar Jayawant N. , Patel Robin
Published: January 2016

Despite known low sensitivity, culture of periprosthetic tissue specimens on agars and in broths is routine. Culture of periprosthetic tissue samples in blood culture bottles (BCBs) is potentially more convenient, but it has been evaluated in a limited way and has not been widely adopted. The aim of this study was to compare the sensitivity and specificity of inoculation of periprosthetic tissue specimens into blood culture bottles with standard agar and thioglycolate broth culture, applying Bayesian latent class modeling (LCM) in addition to applying the Infectious Diseases Society of America (IDSA) criteria for prosthetic joint infection. This prospective cohort study was conducted over a 9-month period (August 2013 to April 2014) at the Mayo Clinic, Rochester, MN, and included all consecutive patients undergoing revision arthroplasty. Overall, 369 subjects were studied; 117 (32%) met IDSA criteria for prosthetic joint infection, and 82% had late chronic infection. Applying LCM, inoculation of tissues into BCBs was associated with a 47% improvement in sensitivity compared to the sensitivity of conventional agar and broth cultures (92.1 versus 62.6%, respectively); this magnitude of change was similar when IDSA criteria were applied (60.7 versus 44.4%, respectively;
P
= 0.003). The time to microorganism detection was shorter with BCBs than with standard media (
P
< 0.0001), with aerobic and anaerobic BCBs yielding positive results within a median of 21 and 23 h, respectively. Results of our study demonstrate that the semiautomated method of periprosthetic tissue culture in blood culture bottles is more sensitive than and as specific as agar and thioglycolate broth cultures and yields results faster.

IMPORTANCE
Prosthetic joint infections are a devastating complication of arthroplasty surgery. Despite this, current microbiological techniques to detect and diagnose infections are imperfect. This study examined a new approach to diagnosing infections, through the inoculation of tissue samples from around the prosthetic joint into blood culture bottles. This study demonstrated that, compared to current laboratory practices, this new technique increased the detection of infection. These findings are important for patient care to allow timely and accurate diagnosis of infection.
An Unexpected Route to an Essential Cofactor: Escherichia coli Relies on Threonine for Thiamine Biosynthesis
Authors: Bazurto Jannell V. , Farley Kristen R. , Downs Diana M.
Published: January 2016

Metabolism consists of biochemical reactions that are combined to generate a robust metabolic network that can respond to perturbations and also adapt to changing environmental conditions.
Escherichia coli
and
Salmonella enterica
are closely related enterobacteria that share metabolic components, pathway structures, and regulatory strategies. The synthesis of thiamine in
S. enterica
has been used to define a node of the metabolic network by analyzing alternative inputs to thiamine synthesis from diverse metabolic pathways. To assess the conservation of metabolic networks in organisms with highly conserved components, metabolic contributions to thiamine synthesis in
E. coli
were investigated. Unexpectedly, we found that, unlike
S. enterica
,
E. coli
does not use the phosphoribosylpyrophosphate (PRPP) amidotransferase (PurF) as the primary enzyme for synthesis of phosphoribosylamine (PRA)
.
In fact, our data showed that up to 50% of the PRA used by
E. coli
to make thiamine requires the activities of threonine dehydratase (IlvA) and anthranilate synthase component II (TrpD). Significantly, the IlvA- and TrpD-dependent pathway to PRA functions in
S. enterica
only in the absence of a functional
r
eactive
i
ntermediate
d
eaminase (RidA) enzyme, bringing into focus how these closely related bacteria have distinct metabolic networks.

IMPORTANCE
In most bacteria, including
Salmonella
strains and
Escherichia coli
, synthesis of the pyrimidine moiety of the essential coenzyme, thiamine pyrophosphate (TPP), shares enzymes with the purine biosynthetic pathway. Phosphoribosylpyrophosphate amidotransferase, encoded by the
purF
gene, generates phosphoribosylamine (PRA) and is considered the first enzyme in the biosynthesis of purines and the pyrimidine moiety of TPP. We show here that, unlike
Salmonella
,
E. coli
synthesizes significant thiamine from PRA derived from threonine using enzymes from the isoleucine and tryptophan biosynthetic pathways. These data show that two closely related organisms can have distinct metabolic network structures despite having similar enzyme components, thus emphasizing caveats associated with predicting metabolic potential from genome content.
Coagulase and Efb of Staphylococcus aureus Have a Common Fibrinogen Binding Motif
Authors: Ko Ya-Ping , Kang Mingsong , Ganesh Vannakambadi K. , Ravirajan Dharmanand , Li Bin , Höök Magnus
Published: January 2016

Coagulase (Coa) and Efb, secreted
Staphylococcus aureus
proteins, are important virulence factors in staphylococcal infections. Coa interacts with fibrinogen (Fg) and induces the formation of fibrin(ogen) clots through activation of prothrombin. Efb attracts Fg to the bacterial surface and forms a shield to protect the bacteria from phagocytic clearance. This communication describes the use of an array of synthetic peptides to identify variants of a linear Fg binding motif present in Coa and Efb which are responsible for the Fg binding activities of these proteins. This motif represents the first Fg binding motif identified for any microbial protein. We initially located the Fg binding sites to Coa’s C-terminal disordered segment containing tandem repeats by using recombinant fragments of Coa in enzyme-linked immunosorbent assay-type binding experiments. Sequence analyses revealed that this Coa region contained shorter segments with sequences similar to the Fg binding segments in Efb. An alanine scanning approach allowed us to identify the residues in Coa and Efb that are critical for Fg binding and to define the Fg binding motifs in the two proteins. In these motifs, the residues required for Fg binding are largely conserved, and they therefore constitute variants of a common Fg binding motif which binds to Fg with high affinity. Defining a specific motif also allowed us to identify a functional Fg binding register for the Coa repeats that is different from the repeat unit previously proposed.

IMPORTANCE
Staphylococcus aureus
infections are a major health problem that affects an estimated 50 million people globally and causes the death of about 20,000 Americans each year. A number of experimental vaccines have been developed during the past years. However, these vaccines have all failed in clinical trials. The ability of
S. aureus
to form an Fg shield surrounding and protecting bacterial cells from clearance may explain why the vaccines are failing. Furthermore,
S. aureus
coagulase can induce the formation of a fibrin(ogen) shield in experimental abscess models which surrounds and protects bacteria in the microcolony from clearance. In this study, we identified for the first time a microbial Fg binding motif. Variants of this motif are present in coagulase and Efb. Our results provide a molecular basis for the rational design of inhibitors that could potentially prevent the formation of the obstructing Fg shield.
Steroids, drugs and stuttering priapism; the rock-and-roll lifestyle of a 24-year-old man
Authors: Evans Lloyd , Larsen Matt , Cox Adam , Skyrme Rob
Published: January 2016

The authors present a case of a 24-year-old, poorly controlled insulin-dependent type 1 diabetic Caucasian man who presented to the emergency department, with a painful erection of 36 h duration that had failed to resolve with conservative management. This was the patient's seventh priapism, with his most recent attendance 1 week previously for which he underwent a distal cavernosal shunt. He admitted to taking several recreational drugs, including marijuana and cocaine, during the preceding few days, in addition to the long-term use of the oral anabolic steroid oxandrolone. He had no family history of sickle cell disease or trait. On examination, a tensely erect penis was noted. A diagnosis of stuttering priapism was made and 750 mL of blood subsequently drained via a distal corporoglandular shunt resulting in successful detumescence.
Successful pregnancy with autoimmune cirrhosis
Authors: Braga António , Braga Jorge
Published: January 2016

Pregnancy with liver cirrhosis is a rare and dangerous event that exposes mother and fetus to potentially lethal risks. During pregnancy, hepatic decompensation could suffice and the development of hepatic failure and encephalopathy could occur. The incidence of obstetric complications is also increased with a high rate of pre-eclampsia, postpartum bleeding, preterm delivery and stillbirth. We report a case of a 27-year-old woman with autoimmune hepatitis and liver cirrhosis complicated by splenomegaly, oesophageal varices and severe thrombocytopaenia. During pregnancy, close clinical and analytical surveillance was performed. She was medicated with corticosteroids, azathioprine and propranolol. At the 25th week of gestation, an upper gastrointestinal endoscopy was performed to control oesophageal varices. This patient had an uneventful pregnancy until 37 weeks. At 37th week of gestation, after spontaneous rupture of membranes, signs of acute fetal distress were observed, and an urgent caesarean was performed. Good neonatal and maternal outcomes were achieved.
Lipoprotein lipase deficiency presenting with neonatal perianal abscesses
Authors: Akesson Lauren S , Burnett John R , Mehta Divyesh K , Martin Andrew C
Published: January 2016

Lipoprotein lipase (LPL), a member of the triglyceride lipase gene family, is synthesised by parenchymal cells of the heart, skeletal muscle and adipose tissues before being transported to luminal surfaces of vascular endothelial cells to exert its main physiological function to hydrolyse plasma lipoproteins. LPL deficiency is a rare autosomal recessive disorder, resulting in severe hypertriglyceridaemia from birth. The effect of marked hypertriglyceridaemia on the immune function in children has not been described. We present a case of a neonate with LPL deficiency and grossly elevated plasma triglyceride levels, presenting with recurrent and recalcitrant perianal abscesses suggestive of underlying immunodeficiency. With reduced levels of plasma triglycerides, the recurrent perianal infections resolved. This case report reviews evidence for potential deleterious effects of hypertriglyceridaemia on immune function, however, underlying mechanisms are poorly understood. Whether hypertriglyceridaemia contributes to immune dysfunction in this context is unknown. If there is a pathophysiological link, this may have implications for hypertriglyceridaemia management.
Ureteric lymphoma as a rare cause of right lower ureteric obstruction
Authors: Sreenivas Jayaram , Mallya Ashwin , Karthikeyan Vilvapathy Senguttuvan , Amirtham Usha
Published: January 2016

Primary lymphoid neoplasms of the urinary tract are exceedingly rare, with only 21 cases being reported and comprising less than 5% of all primary extranodal lymphomas. We report a case of a 45-year-old man who presented with right flank pain and weight loss, and who was found to have a stricture in the right lower ureter causing ureteral obstruction. Histopathology revealed lower ureteric non-Hodgkin lymphoma, which, on further evaluation, was found to be isolated ureteric lymphoma. The patient was doing well after six cycles of R-CHOP chemotherapy. This case is being reported as a rare cause of distal ureteric obstruction.
Palliative care research centre's move into social media: constructing a framework for ethical research, a consensus paper
Authors: Hopewell-Kelly Noreen , Baillie Jessica , Sivell Stephanie , Harrop Emily , Bowyer Anna , Taylor Sophia , Thomas Kristen , Newman Alisha , Prout Hayley , Byrne Anthony , Taubert Mark , Nelson Annmarie
Published: January 2016

Background

Social media (SM) have altered the way we live and, for many, the way we die. The information available on even the rarest conditions is vast. Free from restrictions of mobility, time and distance, SM provides a space for people to share experiences of illness, death and dying, and potentially benefit from the emotional and practical support of others n similar positions. The communications that take place in these spaces also create large amounts of ‘data’ which, for any research centre, cannot be ignored. However, for a palliative care research centre the use of this ‘data’ comes with specific ethical dilemmas.

Methods

This paper details the process that we, as a research, went through in constructing a set of ethical guidelines by which to work. This involved conducting two consensus days; one with researchers from within the centre, and one with the inclusion of external researchers with a specific interest in SM.

Results

The primary themes that emerged from the consensus meetings includes; SM as a public or private space; the status of open and closed groups; the use of historical data; recruiting participants and obtaining informed consent and problems of anonymity associated with dissemination.

Conclusions

These are the themes that this paper will focus on prior to setting out the guidelines that we subsequently constructed.
The relationship between oxidised LDL, endothelial progenitor cells and coronary endothelial function in patients with CHD
Authors: Watt Jonathan , Kennedy Simon , Ahmed Nadeem , Hayhurst James , McClure John D , Berry Colin , Wadsworth Roger M , Oldroyd Keith G
Published: January 2016

Objective

The balance between coronary endothelial dysfunction and repair is influenced by many protective and deleterious factors circulating in the blood. We studied the relationship between oxidised low-density lipoprotein (oxLDL), circulating endothelial progenitor cells (EPCs) and coronary endothelial function in patients with stable coronary heart disease (CHD).

Methods

33 patients with stable CHD were studied. Plasma oxLDL was measured using ELISA, coronary endothelial function was assessed using intracoronary acetylcholine infusion and EPCs were quantified using flow cytometry for CD34+/KDR+cells.

Results

Plasma oxLDL correlated positively with the number of EPCs in the blood (r=0.46, p=0.02). There was a positive correlation between the number of circulating EPCs and coronary endothelial function (r=0.42, p=0.04). There was no significant correlation between oxLDL and coronary endothelial function.

Conclusions

Plasma levels of oxLDL are associated with increased circulating EPCs in the blood of patients with CHD, which may reflect a host-repair response to endothelial injury. Patients with stable CHD had a high prevalence of coronary endothelial dysfunction, which was associated with lower numbers of circulating EPCs, suggesting a mechanistic link between endothelial dysfunction and the pathogenesis of atherosclerosis.
Field hydrological monitoring of a sloping shallow pyroclastic deposit
Authors: Comegna Luca , Damiano Emilia , Greco Roberto , Guida Andrea , Olivares Lucio , Picarelli Luciano
Published: January 2016

Many mountainous areas in Campania, southern Italy, are characterized by steep slopes covered by unsaturated volcanic deposits. Shallow landslides are frequently triggered by intense and persistent rainfall events, often turning into debris flows that cause huge damage and casualties. Field hydrological monitoring is a useful tool to develop consistent models of slope response to rainfall, in terms of soil suction and moisture, and to define landslide triggering conditions. This is one of the reasons why since 2002 field monitoring is being carried out in Cervinara, around 50 km northeast of Naples. Since October 2009, rainfall height, soil suction and water content at several locations and depths along the slope are automatically being monitored. The data collected help to demonstrate the effectiveness of such a system for better understanding the hydrological processes occurring in similar slopes of Campania, allowing to distinguish between seasonal suction fluctuations, related to long-term meteorological forcing, and short-term response to rainstorms.
Geochemical characterization and dating of R tephra, a postglacial marker bed in Mount Rainier National Park, Washington, USA
Authors: Samolczyk Mary A. , Vallance James W. , Cubley Joel F. , Osborn Gerald D. , Clark Douglas H.
Published: January 2016

The oldest postglacial lapilli–ash tephra recognized in sedimentary records surrounding Mount Rainier (Washington State, USA) is R tephra, a very early Holocene deposit that acts as an important stratigraphic and geochronologic marker bed. This multidisciplinary study incorporates tephrostratigraphy, radiocarbon dating, petrography, and electron microprobe analysis to characterize R tephra. Tephra samples were collected from Tipsoo Lake and a stream-cut exposure in the Cowlitz Divide area of Mount Rainier National Park. Field evidence from 25 new sites suggests that R tephra locally contains internal bedding and has a wider distribution than previously reported. Herein, we provide the first robust suite of geochemical data that characterize the tephra. Glass compositions are heterogeneous, predominantly ranging from andesite to rhyolite in ash- to lapilli-sized clasts. The mineral assemblage consists of plagioclase, orthopyroxene, clinopyroxene, and magnetite with trace apatite and ilmenite. Subaerial R tephra deposits appear more weathered in hand sample than subaqueous deposits, but weathering indices suggest negligible chemical weathering in both deposits. Statistical analysis of radiocarbon ages provides a median age for R tephra of ∼10 050 cal years BP, and a 2σ error range between 9960 and 10 130 cal years BP.