bluuebunny/crossref_metadata_2025_split huggingface dataset:
High‐Temperature Split‐Hopkinson Pressure Bar with a Momentum Trap for Obtaining Flow Stress Behaviour and Dynamic Recrystallisation
Authors: Kajberg J. , Sundin K.G. 
Published: October 2014

ABSTRACTIn hot forming processes at elevated temperatures like wire rolling, microstructural changes such as repeated dynamic recrystallisation and grain growth occur. An experimental method to obtain the flow stress behaviour and to capture the recrystallised microstructure for materials subjected to large deformations, high temperatures between 900 and 1200 °C and high strain rates around 5000 s− 1 is presented. The method is based on the split‐Hopkinson pressure bar arrangement complemented with an inductive heat source. Furthermore, a momentum trap is added to ensure that the specimen is loaded only once. By quenching the specimen directly after the single loading, the dynamically recrystallised microstructure is preserved. The quenching is performed within 0.1 s of loading by dropping the specimen into a water bath. By applying the momentum trap technique, the compressive loading of the specimen could be interrupted at a strain level slightly above the strain level corresponding to the peak stress, which is a good estimation for the onset of dynamic recrystallisation.
Hepatitis C virus acquisition among Egyptians: analysis of a 10‐year surveillance of acute hepatitis C
Authors: Mohsen Amira , Bernier Adeline , LeFouler Lenaig , Delarocque‐Astagneau Elisabeth , El‐Daly Mai , El‐Kafrawy Sherif , El‐Mango Salwa , Abdel‐Hamid Mohamed , Gadallah Mohsen , Esmat Gamal , Mohamed Mostafa K. , Fontanet Arnaud 
Published: October 2014

AbstractObjectiveTo identify current risk factors for hepatitis C virus (HCV) acquisition among Egyptians.MethodsPatients with acute HCV were identified through a surveillance system of acute hepatitis in four fever hospitals in Egypt between 2002 and 2012. Case–control analysis was conducted, cases being incident acute symptomatic HCV and controls being acute hepatitis A identified at the same hospitals. The questionnaire covered iatrogenic, community and household exposures to HCV in the 1–6 months prior to onset of symptoms. Multivariate models were built to identify risk factors associated with HCV acquisition among non‐drug users and drug users separately.ResultsAmong non‐drug users, hospital admission was independently associated with acute HCV infection (OR = 4.2, 95% CI = 1.7–10.5). Several iatrogenic procedures, for example admission in a surgery unit, sutures, IV injections and IV infusions, highly correlated with hospital admission, were also associated with acute HCV infection and could have been used in the final model instead of hospital admission. Among drug users, identified risk factors were multiple sexual relations (OR = 4.0, 95% CI = 1.1–14.7), intravenous drug use (OR = 3.9, 95% CI = 1.2–13.0) and shaving at the barbershops (OR = 8.7, 95% CI = 2.4–31.4). Illiteracy and marriage were significant risk factors in both groups.ConclusionInvasive medical procedures are still a major risk for acquiring new HCV infections in Egypt, as is illicit drug use in spreading HCV infection.
Genetic variation of the invasive Campuloclinium macrocephalum, Asteraceae in South Africa, inferred from molecular markers
Authors: Gitonga L , Cron G V , McConnachie A , Byrne M J 
Published: October 2014

SummaryCampuloclinium macrocephalum is native to Central and South America, but is a highly invasive weed in South Africa, where it is commonly known as the ‘pompom weed’. It is targeted for biological control, the success of which will depend on host specificity and biotype compatibility to its full genetic diversity in South Africa. We investigated the genetic diversity and phylogeography of 52 specimens from across South Africa, 14 from Argentina and three from Brazil using nuclear ribosomal ITS regions. We further explored the AFLP marker diversity in 54 South African, 25 Argentine and three Brazilian specimens. Maximum parsimony analysis of the ITS sequence data produced an unresolved phylogeny. However, three haplotypes were recognised via network analysis. All South African, one Brazilian and all bar one of the Argentine individuals shared a single haplotype. AFLP analyses generated two genetic clusters with a low net nucleotide distance of 0.115 and further revealed that most plants were a mixture of alleles from these two genetic clusters. Although there was a significant genetic variation among the populations, genetic differentiation and mean heterozygosity were low, suggesting that clonal reproduction may be occurring. The current South African populations may therefore be clonal products with different proportions of genetic admixture introduced more than once. The original point of entry appears to be Gauteng, South Africa. Long‐distance dispersal appears to have played a major role in its spread across South Africa. Candidate Argentine biological control agents should therefore be effective on C. macrocephalum in South Africa.
Spatial variation of dosimetric leaf gap and its impact on dose delivery
Authors: Kumaraswamy Lalith K. , Schmitt Jonathan D. , Bailey Daniel W. , Xu Zheng Zheng , Podgorsak Matthew B. 
Published: October 2014

Purpose:During dose calculation, the Eclipse treatment planning system (TPS) retracts the multileaf collimator (MLC) leaf positions by half of the dosimetric leaf gap (DLG) value (measured at central axis) for all leaf positions in a dynamic MLC plan to accurately model the rounded leaf ends. The aim of this study is to map the variation of DLG along the travel path of each MLC leaf pair and quantify how this variation impacts delivered dose.Methods:6 MV DLG values were measured for all MLC leaf pairs in increments of 1.0 cm (from the line intersecting the CAX and perpendicular to MLC motion) to 13.0 cm off axis distance at dmax. The measurements were performed on two Varian linear accelerators, both employing the Millennium 120‐leaf MLCs. The measurements were performed at several locations in the beam with both a Sun Nuclear MapCHECK device and a PTW pinpoint ion chamber.Results:The measured DLGs for the middle 40 MLC leaf pairs (each 0.5 cm width) at positions along a line through the CAX and perpendicular to MLC leaf travel direction were very similar, varying maximally by only 0.2 mm. The outer 20 MLC leaf pairs (each 1.0 cm width) have much lower DLG values, about 0.3–0.5 mm lower than the central MLC leaf pair, at their respective central line position. Overall, the mean and the maximum variation between the 0.5 cm width leaves and the 1.0 cm width leaf pairs are 0.32 and 0.65 mm, respectively.Conclusions:The spatial variation in DLG is caused by the variation of intraleaf transmission through MLC leaves. Fluences centered on the CAX would not be affected since DLG does not vary; but any fluences residing significantly off axis with narrow sweeping leaves may exhibit significant dose differences. This is due to the fact that there are differences in DLG between the true DLG exhibited by the 1.0 cm width outer leaves and the constant DLG value utilized by the TPS for dose calculation. Since there are large differences in DLG between the 0.5 cm width leaf pairs and 1.0 cm width leaf pairs, there is a need to correct the TPS plans, especially those with high modulation (narrow dynamic MLC gap), with 2D variation of DLG.
Quality assurance for the clinical implementation of kilovoltage intrafraction monitoring for prostate cancer VMAT
Authors: Ng J. A. , Booth J. T. , O'Brien R. T. , Colvill E. , Huang C.‐Y. , Poulsen P. R. , Keall P. J. 
Published: October 2014

Purpose:Kilovoltage intrafraction monitoring (KIM) is a real‐time 3D tumor monitoring system for cancer radiotherapy. KIM uses the commonly available gantry‐mounted x‐ray imager as input, making this method potentially more widely available than dedicated real‐time 3D tumor monitoring systems. KIM is being piloted in a clinical trial for prostate cancer patients treated with VMAT (NCT01742403). The purpose of this work was to develop clinical process and quality assurance (QA) practices for the clinical implementation of KIM.Methods:Informed by and adapting existing guideline documents from other real‐time monitoring systems, KIM‐specific QA practices were developed. The following five KIM‐specific QA tests were included: (1) static localization accuracy, (2) dynamic localization accuracy, (3) treatment interruption accuracy, (4) latency measurement, and (5) clinical conditions accuracy. Tests (1)–(4) were performed using KIM to measure static and representative patient‐derived prostate motion trajectories using a 3D programmable motion stage supporting an anthropomorphic phantom with implanted gold markers to represent the clinical treatment scenario. The threshold for system tolerable latency is <1 s. The tolerances for all other tests are that both the mean and standard deviation of the difference between the programmed trajectory and the measured data are <1 mm. The (5) clinical conditions accuracy test compared the KIM measured positions with those measured by kV/megavoltage (MV) triangulation from five treatment fractions acquired in a previous pilot study.Results:For the (1) static localization, (2) dynamic localization, and (3) treatment interruption accuracy tests, the mean and standard deviation of the difference are <1.0 mm. (4) The measured latency is 350 ms. (5) For the tests with previously acquired patient data, the mean and standard deviation of the difference between KIM and kV/MV triangulation are <1.0 mm.Conclusions:Clinical process and QA practices for the safe clinical implementation of KIM, a novel real‐time monitoring system using commonly available equipment, have been developed and implemented for prostate cancer VMAT.
Radiation dose calculations for CT scans with tube current modulation using the approach to equilibrium function
Authors: Li Xinhua , Zhang Da , Liu Bob 
Published: October 2014

Purpose:The approach to equilibrium function has been used previously to calculate the radiation dose to a shift‐invariant medium undergoing CT scans with constant tube current [Li, Zhang, and Liu, Med. Phys. 39, 5347–5352 (2012)]. The authors have adapted this method to CT scans with tube current modulation (TCM).Methods:For a scan with variable tube current, the scan range was divided into multiple subscan ranges, each with a nearly constant tube current. Then the dose calculation algorithm presented previously was applied. For a clinical CT scan series that presented tube current per slice, the authors adopted an efficient approach that computed the longitudinal dose distribution for one scan length equal to the slice thickness, which center was at z = 0. The cumulative dose at a specific point was a summation of the contributions from all slices and the overscan.Results:The dose calculations performed for a total of four constant and variable tube current distributions agreed with the published results of Dixon and Boone [Med. Phys. 40, 111920 (14pp.) (2013)]. For an abdomen/pelvis scan of an anthropomorphic phantom (model ATOM 701‐B, CIRS, Inc., VA) on a GE Lightspeed Pro 16 scanner with 120 kV, N × T = 20 mm, pitch = 1.375, z axis current modulation (auto mA), and angular current modulation (smart mA), dose measurements were performed using two lines of optically stimulated luminescence dosimeters, one of which was placed near the phantom center and the other on the surface. Dose calculations were performed on the central and peripheral axes of a cylinder containing water, whose cross‐sectional mass was about equal to that of the ATOM phantom in its abdominal region, and the results agreed with the measurements within 28.4%.Conclusions:The described method provides an effective approach that takes into account subject size, scan length, and constant or variable tube current to evaluate CT dose to a shift‐invariant medium. For a clinical CT scan, dose calculations may be performed with a water‐containing cylinder whose cross‐sectional mass is equal to that of the subject. This method has the potential to substantially improve evaluations of patient dose from clinical CT scans, compared to CTDIvol, size‐specific dose estimate (SSDE), or the dose evaluated for a TCM scan with a constant tube current equal to the average tube current of the TCM scan.
Origin in Acinetobacter guillouiae and Dissemination of the Aminoglycoside-Modifying Enzyme Aph(3′)-VI
Authors: Yoon Eun-Jeong , Goussard Sylvie , Touchon Marie , Krizova Lenka , Cerqueira Gustavo , Murphy Cheryl , Lambert Thierry , Grillot-Courvalin Catherine , Nemec Alexandr , Courvalin Patrice 
Published: October 2014

ABSTRACT

The amikacin resistance gene
aphA6
was first detected in the nosocomial pathogen
Acinetobacter baumannii
and subsequently in other genera. Analysis of 133 whole-genome sequences covering the taxonomic diversity of
Acinetobacter
spp. detected
aphA6
in the chromosome of 2 isolates of
A. guillouiae
, which is an environmental species, 1 of 8
A. parvus
isolates, and 5 of 34
A. baumannii
isolates. The gene was also present in 29 out of 36
A. guillouiae
isolates screened by PCR, indicating that it is ancestral to this species. The
P
native
promoter for
aphA6
in
A. guillouiae
and
A. parvus
was replaced in
A. baumannii
by
P

aphA6

, which was generated by use of the insertion sequence IS
Aba125
, which brought a −35 sequence. Study of promoter strength in
Escherichia coli
and
A. baumannii
indicated that
P

aphA6

was four times more potent than
P
native
. There was a good correlation between aminoglycoside MICs and
aphA6
transcription in
A. guillouiae
isolates that remained susceptible to amikacin. The marked topology differences of the phylogenetic trees of
aphA6
and of the hosts strongly support its recent direct transfer within
Acinetobacter
spp. and also to evolutionarily remote bacterial genera. Concomitant expression of
aphA6
must have occurred because, contrary to the donors, it can confer resistance to the new hosts. Mobilization and expression of
aphA6
via composite transposons and the upstream IS-generating hybrid
P

aphA6

, followed by conjugation, seems the most plausible mechanism. This is in agreement with the observation that, in the recipients,
aphA6
is carried by conjugative plasmids and flanked by IS that are common in
Acinetobacter
spp. Our data indicate that resistance genes can also be found in susceptible environmental bacteria.

IMPORTANCE
We speculated that the
aphA6
gene for an enzyme that confers resistance to amikacin, the most active aminoglycoside for the treatment of nosocomial infections due to
Acinetobacter
spp., originated in this genus before disseminating to phylogenetically distant genera pathogenic for humans. Using a combination of whole-genome sequencing of a collection of
Acinetobacter
spp. covering the breadth of the known taxonomic diversity of the genus, gene cloning, detailed promoter analysis, study of heterologous gene expression, and comparative analysis of the phylogenetic trees of
aphA6
and of the bacterial hosts, we found that
aphA6
originated in
Acinetobacter guillouiae
, an amikacin-susceptible environmental species. The gene conferred, upon mobilization, high-level resistance to the new hosts. This work stresses that nonpathogenic bacteria can act as reservoirs of resistance determinants, and it provides an example of the use of a genomic library to study the origin and dissemination of an antibiotic resistance gene to human pathogens.
Emergence of a New Epidemic Neisseria meningitidis Serogroup A Clone in the African Meningitis Belt: High-Resolution Picture of Genomic Changes That Mediate Immune Evasion
Authors: Lamelas Araceli , Harris Simon R. , Röltgen Katharina , Dangy Jean-Pierre , Hauser Julia , Kingsley Robert A. , Connor Thomas R. , Sie Ali , Hodgson Abraham , Dougan Gordon , Parkhill Julian , Bentley Stephen D. , Pluschke Gerd 
Published: October 2014

ABSTRACT

In the African “meningitis belt,” outbreaks of meningococcal meningitis occur in cycles, representing a model for the role of host-pathogen interactions in epidemic processes. The periodicity of the epidemics is not well understood, nor is it currently possible to predict them. In our longitudinal colonization and disease surveys, we have observed waves of clonal replacement with the same serogroup, suggesting that immunity to noncapsular antigens plays a significant role in natural herd immunity. Here, through comparative genomic analysis of 100 meningococcal isolates, we provide a high-resolution view of the evolutionary changes that occurred during clonal replacement of a hypervirulent meningococcal clone (ST-7) by a descendant clone (ST-2859). We show that the majority of genetic changes are due to homologous recombination of laterally acquired DNA, with more than 20% of these events involving acquisition of DNA from other species. Signals of adaptation to evade herd immunity were indicated by genomic hot spots of recombination. Most striking is the high frequency of changes involving the
pgl
locus, which determines the glycosylation patterns of major protein antigens. High-frequency changes were also observed for genes involved in the regulation of pilus expression and the synthesis of Maf3 adhesins, highlighting the importance of these surface features in host-pathogen interaction and immune evasion.

IMPORTANCE
While established meningococcal capsule polysaccharide vaccines are protective through the induction of anticapsular antibodies, findings of our longitudinal studies in the African meningitis belt have indicated that immunity to noncapsular antigens plays a significant role in natural herd immunity. Our results show that meningococci evade herd immunity through the rapid homologous replacement of just a few key genomic loci that affect noncapsular cell surface components. Identification of recombination hot spots thus represents an eminent approach to gain insight into targets of protective natural immune responses. Moreover, our results highlight the role of the dynamics of the protein glycosylation repertoire in immune evasion by
Neisseria meningitidis
. These results have major implications for the design of next-generation protein-based subunit vaccines.
Proteolytic Processing and Activation of Clostridium perfringens Epsilon Toxin by Caprine Small Intestinal Contents
Authors: Freedman John C. , Li Jihong , Uzal Francisco A. , McClane Bruce A. 
Published: October 2014

ABSTRACT

Epsilon toxin (ETX), a pore-forming toxin produced by type B and D strains of
Clostridium perfringens
, mediates severe enterotoxemia in livestock and possibly plays a role in human disease. During enterotoxemia, the nearly inactive ETX prototoxin is produced in the intestines but then must be activated by proteolytic processing. The current study sought to examine ETX prototoxin processing and activation
ex vivo
using the intestinal contents of a goat, a natural host species for ETX-mediated disease. First, this study showed that the prototoxin has a KEIS N-terminal sequence with a molecular mass of 33,054 Da. When the activation of ETX prototoxin
ex vivo
by goat small intestinal contents was assessed by SDS-PAGE, the prototoxin was processed in a stepwise fashion into an ~27-kDa band or higher-molecular-mass material that could be toxin oligomers. Purified ETX corresponding to the ~27-kDa band was cytotoxic. When it was biochemically characterized by mass spectrometry, the copresence of three ETX species, each with different C-terminal residues, was identified in the purified ~27-kDa ETX preparation. Cytotoxicity of each of the three ETX species was then demonstrated using recombinant DNA approaches. Serine protease inhibitors blocked the initial proteotoxin processing, while carboxypeptidase inhibitors blocked further processing events. Taken together, this study provides important new insights indicating that, in the intestinal lumen, serine protease (including trypsin and possibly chymotrypsin) initiates the processing of the prototoxin but other proteases, including carboxypeptidases, then process the prototoxin into multiple active and stable species.

IMPORTANCE
Processing and activation by intestinal proteases is a prerequisite for ETX-induced toxicity. Previous studies had characterized the activation of ETX using only arbitrarily chosen amounts of purified trypsin and/or chymotrypsin. Therefore, the current study examined ETX activation
ex vivo
by natural host intestinal contents. These analyses demonstrated that (i) ETX processing in host intestinal contents occurs in an ordered, stepwise fashion, (ii) processing of prototoxin by host intestinal contents results in higher-molecular-mass material and 3 distinct ~27-kDa ETX species, and (iii) serine proteases, such as trypsin, chymotrypsin, and other proteases, including carboxypeptidases, play a role in the activation of ETX by intestinal contents. These studies provide new insights into the activation and processing of ETX and demonstrate that this process is more complicated than previously appreciated.
The Effect of Electroacupuncture on Tendon Repair in a Rat Achilles Tendon Rupture Model
Authors: Inoue Motohiro , Nakajima Miwa , Oi Yuki , Hojo Tatsuya , Itoi Megumi , Kitakoji Hiroshi 
Published: October 2014

Objective To examine the effect of electroacupuncture (EA) on early post-rupture tendon repair in a rat model of Achilles tendon rupture using histological and mechanical evaluation. Methods An Achilles tendon rupture model was prepared in 90 Wistar rats, which were randomly assigned to EA, manual acupuncture or control groups. Rats in the EA group received EA (pulse width 5 ms; stimulation frequency 50 Hz; stimulation strength 20 μA; stimulation time 20 min) daily from 1 day following model preparation until the day of assessment (either 7 or 10 days after model preparation), when the region of interest was sampled to assess tendon repair using in vitro methods. Total cell count and the number of cells staining positive for transforming growth factor-β1 (TGF-β1) and basic fibroblast growth factor (b-FGF) were measured. Tension tests were performed 10 days after model preparation to measure the maximum breaking strength of the repaired tendon. Results Both the total cell count and the number of cells positive for b-FGF were significantly higher in the EA group (p<0.05). In the EA group only, immunostaining showed strong expression of TGF-β1 7 days after model preparation (p<0.05). Maximum breaking strength of the repaired tendon 10 days after model preparation was significantly higher in the EA group (p<0.01). Conclusions The marked increase in cell count and growth factor expression as well as increased tendon strength in the EA group suggest that EA may be a useful method for promoting tendon repair.