bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heating and Loading Paths to Optimize the Performance of Trained Shape Memory Alloy Torsional Actuators
Authors: Nicholson Douglas E. , Bass Micheal A. , Mabe James H. , Benafan Othmane , Padula Santo A. , Vaidyanathan Raj 
Published: November 2016

Near-equiatomic NiTi shape memory alloy (SMA) torsional tube actuators were trained for two-way shape memory effect (TWSME) by repeated thermal cycling under an isobaric load. Performance of the trained actuators was assessed by thermally cycling through a complete phase transformation under a range of isobaric loads that varied from negative to positive and included loads near zero. To assess the actuation performance of the trained SMA components, extended isobaric thermal cycling and cycling under varying loads to constant strain limits was performed. Additionally, isothermal loading was applied in the fully martensitic state prior to and following training.
Results show stable TWSME when cycling under significant isobaric loading in the trained direction, however at low or negative loads (loads applied opposite to the training direction) a degradation of TWSME occurred during thermal cycling. Isothermal loading showed that martensite variant reorientation and detwinning was redistributed in the trained actuator when compared to an untrained actuator. Thermal cycling against constant strain limits was shown to have a negligible effect on the stability of the TWSME and overall performance of the trained actuator. Various combinations of isothermal and isobaric loading were shown to expand the operating range at low and negative loads. Additionally, load paths were identified which limit the degradation of TWSME over extended cycling.
The aforementioned results are discussed in the context of the correlation between uniaxial isobaric and isothermal loading and texture measurements obtained by in-situ neutron diffraction at stress and temperature. These results show various thermomechanical combinations of heating and loading sequences that yield the same final martensite texture in SMA, which highlights the ability to take different paths yet still obtain the desired actuator response while minimizing irrecoverable deformation mechanisms. The implications of extending these uniaxial results to the design and fabrication and ultimately improving the performance of torsional SMA actuators are discussed.
Equivalent Electromechanical Circuit Analysis for Electrical Tuning of Magnetostrictive Unimorph System Dynamics
Authors: Germer M. , Marschner U. , Yoo J. H. , Flatau A. B. 
Published: November 2016

Equivalent electromechanical circuit analysis models provide efficient tools for analysis of power flow across multiple physical domains. In this work, we use this tool to develop a model of the power flow through mechanical, magnetic and electrical domains for analysis of magnetostrictive material-based devices. The magnetostrictive unimorph system in this study consists of a magnetostrictive galfenol (Fe-Ga alloy) layer bonded to a non-magnetic flexible metal layer, a pickup coil wound around the bimetallic strip and an electrical load. Permanent magnets are used to set a magnetic bias field and to provide a tip mass load at the free end of the cantilevered unimorph. The electrical load is connected to the pickup coil, such that vibration in the magnetostrictive alloy layer caused by the vibrating structure generates electrical energy that is dissipated by the electrical load, thereby damping the vibrations in the structure. The pickup coil output voltage varies with fluctuation in the magnetic flux density due to vibration of the beam.
The electrical load discussed in this paper includes an inductance and a resistor (work that also includes capacitance is on-going). An electromechanical circuit model of the electrically loaded magnetostrictive unimorph system is used to study system dynamics. For this purpose the circuit description is simplified by a transformation of the electrical and magnetic elements into the mechanical domain. The network model of this system and simulations of its dynamic behavior are presented.
Stiffness Tuning of NiTi Implants Through Aging
Authors: Shayesteh Moghaddam Narges , Amerinatanzi Amirhesam , Saedi Soheil , Turabi Ali Sadi , Karaca Haluk , Elahinia Mohammad 
Published: November 2016

NiTi alloys are interesting materials for biomedical implants since they offer unique characteristics such as superelastic behavior, low stiffness (I.e., modulus of elasticity) close to that of the cortical bone, and shock absorption. Thermal treatments are the most common and practical ways to improve the superelasticity of these alloys. In addition to the superelastic behavior of the metallic implants, it is important for the implants to have a stiffness similar to that of cortical bone in order to reduce the risk of failure caused by stress shielding. The cortical bone has a stiffness ranging from 12 to 31 GPa for different patients (e.g., sex, age, mechanical behavior of bone) and various bone locations (e.g., jaw implant, hip implant), while the untreated Ni-rich NiTi has the stiffness equal to 41.37 GPa. One recently used technique to lower the stiffness of NiTi implant is to introduce porosity into the implant. The major problem associated with the imposed porosity is stress concentration on the pore walls and the subsequent implant failure. In this work, the purpose is to tune the stiffness via changing the post-heat treatment conditions, i.e., aging time and aging temperature.
In this study, several bulk specimens of Ni-rich NiTi (SLM Ni50.8Ti49.2) were additively manufactured using selective laser melting (SLM) technique. The samples were solution annealed (950 °C, 5.5 h) and subsequently water quenched to provide equilibrium state in the samples. Subsequently, different aging conditions (350 °C and 450 °C for 5 to 18 hours) were applied to the samples. Mechanical testing (compression) was conducted on the samples and the stiffness of each sample was defined to investigate the effect of aging on the stiffness.
Our results indicate that the range of 29.9 to 43.7 GPa for stiffness can be achieved through the implant via different time period and temperatures for aging. The modulus of 43.7 GPa is attributed to 10 hours heat treatment under 450 °C and the modulus of 29.9 GPa is attributed to 18 hours heat treatment under 350 °C.
Protective Effects of Human and Mouse Soluble Scavenger-Like CD6 Lymphocyte Receptor in a Lethal Model of Polymicrobial Sepsis
Authors: Martínez-Florensa Mario , Consuegra-Fernández Marta , Aranda Fernando , Armiger-Borràs Noelia , Di Scala Marianna , Carrasco Esther , Pachón Jerónimo , Vila Jordi , González-Aseguinolaza Gloria , Lozano Francisco 
Published: November 2016

ABSTRACT
Sepsis still constitutes an unmet clinical need, which could benefit from novel adjunctive strategies to conventional antibiotic therapy. The soluble form of the scavenger-like human CD6 lymphocyte receptor (shCD6) binds to key pathogenic components from Gram-positive and -negative bacteria and shows time- and dose-dependent efficacy in mouse models of monobacterial sepsis. The objective of the present work was to demonstrate the effectiveness of infusing mouse and human sCD6 by different systemic routes, either alone or as adjunctive therapy to gold standard antibiotics, in a lethal model of polymicrobial sepsis. To this end, C57BL/6 mice undergoing high-grade septic shock induced by cecal ligation and puncture (CLP; ≥90% lethality) were infused via the intraperitoneal (i.p.) or intravenous (i.v.) route with shCD6 at different doses and time points, either alone or in combination with imipenem/cilastatin (I/C) at a dose of 33 mg/kg of body weight every 8 h. Significantly reduced mortality and proinflammatory cytokine levels were observed by i.p. infusion of a single shCD6 dose (1.25 mg/kg) 1 h pre- or post-CLP. When using the i.v. route, mice survival was significantly extended by starting shCD6 infusion at later time points post-CLP (up to 6 h after CLP). Significant adjunctive effects on mouse survival were observed by i.p. or i.v. infusion of shCD6 in combination with i.p. I/C post-CLP. Similar results were obtained in mice expressing high sustained levels (5 to 10 μg/ml) of mouse sCD6 in serum by means of transduction with hepatotropic adeno-associated virus (AAV). Taken together, the data support the conserved antibacterial effects of human and mouse sCD6 and their use as adjunctive therapy in experimental models of complex and severe polymicrobial sepsis.
A Naturally Occurring Single Nucleotide Polymorphism in a Multicopy Plasmid Produces a Reversible Increase in Antibiotic Resistance
Authors: Santos-Lopez Alfonso , Bernabe-Balas Cristina , Ares-Arroyo Manuel , Ortega-Huedo Rafael , Hoefer Andreas , San Millan Alvaro , Gonzalez-Zorn Bruno 
Published: November 2016

ABSTRACT

ColE1 plasmids are small mobilizable replicons that play an important role in the spread of antibiotic resistance in
Pasteurellaceae
. In this study, we describe how a natural single nucleotide polymorphism (SNP) near the origin of replication of the ColE1-type plasmid pB1000 found in a
Pasteurella multocida
clinical isolate generates two independent plasmid variants able to coexist in the same cell simultaneously. Using the
Haemophilus influenzae
Rd KW20 strain as a model system, we combined antibiotic susceptibility tests, quantitative PCRs, competition assays, and experimental evolution to characterize the consequences of the coexistence of the pB1000 plasmid variants. This coexistence produced an increase of the total plasmid copy number (PCN) in the host bacteria, leading to a rise in both the antibiotic resistance level and the metabolic burden produced by pB1000. Using experimental evolution, we showed that in the presence of ampicillin, the bacteria maintained both plasmid variants for 300 generations. In the absence of antibiotics, on the other hand, the bacteria are capable of reverting to the single-plasmid genotype via the loss of one of the plasmid variants. Our results revealed how a single mutation in plasmid pB1000 provides the bacterial host with a mechanism to increase the PCN and, consequently, the ampicillin resistance level. Crucially, this mechanism can be rapidly reversed to avoid the extra cost entailed by the increased PCN in the absence of antibiotics.
Ceftazidime-Avibactam as Salvage Therapy for Infections Caused by Carbapenem-Resistant Organisms
Authors: Temkin Elizabeth , Torre-Cisneros Julian , Beovic Bojana , Benito Natividad , Giannella Maddalena , Gilarranz Raúl , Jeremiah Cameron , Loeches Belén , Machuca Isabel , Jiménez-Martín María José , Martínez José Antonio , Mora-Rillo Marta , Navas Enrique , Osthoff Michael , Pozo Juan Carlos , Ramos Ramos Juan Carlos , Rodriguez Marina , Sánchez-García Miguel , Viale Pierluigi , Wolff Michel , Carmeli Yehuda 
Published: November 2016

ABSTRACT

Ceftazidime-avibactam (CAZ-AVI) is a recently approved β-lactam–β-lactamase inhibitor combination with the potential to treat serious infections caused by carbapenem-resistant organisms. Few patients with such infections were included in the CAZ-AVI clinical trials, and clinical experience is lacking. We present a case series of patients with infections caused by carbapenem-resistant
Enterobacteriaceae
(CRE) or
Pseudomonas aeruginosa
(CRPa) who were treated with CAZ-AVI salvage therapy on a compassionate-use basis. Physicians who had prescribed CAZ-AVI completed a case report form. We used descriptive statistics to summarize patient characteristics and treatment outcomes. We used the Wilcoxon rank sum test and Fisher's exact test to compare patients by treatment outcome. The sample included 36 patients infected with CRE and two with CRPa. The most common infections were intra-abdominal. Physicians categorized 60.5% of patients as having life-threatening infections. All but two patients received other antibiotics before CAZ-AVI, for a median of 13 days. The median duration of CAZ-AVI treatment was 16 days. Twenty-five patients (65.8%) concurrently received other antibiotics to which their pathogen was nonresistant
in vitro
. Twenty-eight patients (73.7%, 95% confidence interval [CI], 56.9 to 86.6%) experienced clinical and/or microbiological cure. Five patients (20.8%) with documented microbiological cure died, whereas 10 patients (71.4%) with no documented microbiological cure died (
P
= 0.01). In three-quarters of cases, CAZ-AVI (alone or combined with other antibiotics) cured infections caused by carbapenem-resistant organisms, 95% of which had failed previous therapy. Microbiological cure was associated with improved survival. CAZ-AVI shows promising clinical results for infections for which treatment options are limited.
Occurrence of Diverse AbGRI1-Type Genomic Islands in Acinetobacter baumannii Global Clone 2 Isolates from South Korea
Authors: Kim Dae Hun , Jung Sook-In , Kwon Ki Tae , Ko Kwan Soo 
Published: November 2016

ABSTRACT

In this study, we analyzed the frequency of the AbGRI1-type genomic island (GI) and its association with genotypes. We obtained 130
Acinetobacter baumannii
isolates causing bloodstream infections from patients in South Korea. Antimicrobial susceptibility testing and multilocus sequence typing were performed. The presence of AbGRI1-type GIs and their structures were determined by sequential PCR and sequencing. Ninety-eight isolates (75.3%) representing 14 sequence types (STs) belonged to clonal complex 208 (CC208), corresponding to global clone 2 (GC2). AbGRI1-type GIs interrupted the
comM
gene in 107 isolates (82.4%). Four types of GIs were identified: Tn
6022
(50 isolates; 46.7%), AbaR4 (23 isolates; 21.5%), Tn
6166
(10 isolates; 9.3%), and Tn
6166
/Tn
2006
(24 isolates; 22.4%). In the 50 isolates with Tn
6022
, Tn
2006
or Tn
2008B
, both containing IS
Aba1-bla
OXA-23
, was present in sites other than GIs in 3 or 28 isolates, respectively. In the 10 isolates with Tn
6166
, Tn
2008B
was identified in one isolate. AbGRI1-type GIs were identified nearly exclusively in CC208 isolates, with the exception of nine non-CC208 isolates (AbaR4 in eight ST229 isolates and Tn
6022
in one ST1244 isolate). Within CC208 isolates, there was evidence of frequent recombination events, in both housekeeping genes and AbGRI1-type GIs, contributing to genotype diversification and the emergence of carbapenem resistance.
Mutations Associated with Decreased Susceptibility to Seven Antimicrobial Families in Field and Laboratory-Derived Mycoplasma bovis Strains
Authors: Sulyok Kinga M. , Kreizinger Zsuzsa , Wehmann Enikő , Lysnyansky Inna , Bányai Krisztián , Marton Szilvia , Jerzsele Ákos , Rónai Zsuzsanna , Turcsányi Ibolya , Makrai László , Jánosi Szilárd , Nagy Sára Ágnes , Gyuranecz Miklós 
Published: November 2016

ABSTRACT

The molecular mechanisms of resistance to fluoroquinolones, tetracyclines, an aminocyclitol, macrolides, a lincosamide, a phenicol, and pleuromutilins were investigated in
Mycoplasma bovis
. For the identification of mutations responsible for the high MICs of certain antibiotics, whole-genome sequencing of 35
M. bovis
field isolates and 36 laboratory-derived antibiotic-resistant mutants was performed.
In vitro
resistant mutants were selected by serial passages of
M. bovis
in broth medium containing subinhibitory concentrations of the antibiotics. Mutations associated with high fluoroquinolones MICs were found at positions 244 to 260 and at positions 232 to 250 (according to
Escherichia coli
numbering) of the quinolone resistance-determining regions of the
gyrA
and
parC
genes, respectively. Alterations related to elevated tetracycline MICs were described at positions 962 to 967, 1058, 1195, 1196, and 1199 of genes encoding the 16S rRNA and forming the primary tetracycline binding site. Single transversion at position 1192 of the
rrs1
gene resulted in a spectinomycin MIC of 256 μg/ml. Mutations responsible for high macrolide, lincomycin, florfenicol, and pleuromutilin antibiotic MICs were identified in genes encoding 23S rRNA. Understanding antibiotic resistance mechanisms is an important tool for future developments of genetic-based diagnostic assays for the rapid detection of resistant
M. bovis
strains.
Multicenter Observational Study of Ceftaroline Fosamil for Methicillin-Resistant Staphylococcus aureus Bloodstream Infections
Authors: Zasowski Evan J. , Trinh Trang D. , Claeys Kimberly C. , Casapao Anthony M. , Sabagha Noor , Lagnf Abdalhamid M. , Klinker Kenneth P. , Davis Susan L. , Rybak Michael J. 
Published: November 2016

ABSTRACT

Novel therapies for methicillin-resistant
Staphylococcus aureus
(MRSA) bloodstream infection (BSI) are needed in the setting of reduced antibiotic susceptibilities and therapeutic failure. Ceftaroline is a cephalosporin antibiotic with MRSA activity. Although not FDA approved for MRSA BSI, ceftaroline has generated much interest as a potential treatment option. However, detailed descriptions of its use in this setting remain limited. To address this, we conducted a retrospective, multicenter, observational study of adult patients with MRSA BSI treated with at least 72 h of ceftaroline from 2011 to 2015. Safety outcomes were examined in the overall cohort, while efficacy outcomes were examined among patients who had not cleared their BSI prior to ceftaroline initiation. Data were also stratified by ceftaroline monotherapy or combination therapy. Predictors of clinical failure on ceftaroline treatment were also sought. Overall, 211 patients were included in the safety population;
Clostridium difficile
infection, rash, and neutropenia occurred in 6 patients (2.8%), 7 patients (3.3%), and 3 patients (1.4%), respectively. Clinical success was observed in 86 (68.3%) of the 126 patients included in the efficacy population. The monotherapy and combination therapy subgroups had similar proportions of patients experiencing success (69.7 and 64.9%, respectively). The median BSI durations post-ceftaroline treatment were 2 days (interquartile range, 1 to 4 days) for monotherapy and 3 days (interquartile range, 1.5 to 5 days) for combination therapy. Higher acute physiology and chronic health evaluation II scores and comorbid malignancy independently predicted treatment failure. Ceftaroline appears effective for MRSA BSI as both monotherapy and combination therapy. However, comparative studies are needed to further delineate the role of ceftaroline in MRSA BSI treatment.
Characterization of the Pathogenicity of Streptococcus intermedius TYG1620 Isolated from a Human Brain Abscess Based on the Complete Genome Sequence with Transcriptome Analysis and Transposon Mutagenesis in a Murine Subcutaneous Abscess Model
Authors: Hasegawa Noriko , Sekizuka Tsuyoshi , Sugi Yutaka , Kawakami Nobuhiro , Ogasawara Yumiko , Kato Kengo , Yamashita Akifumi , Takeuchi Fumihiko , Kuroda Makoto 
Published: November 2016

ABSTRACT

Streptococcus intermedius
is known to cause periodontitis and pyogenic infections in the brain and liver. Here we report the complete genome sequence of strain TYG1620 (genome size, 2,006,877 bp; GC content, 37.6%; 2,020 predicted open reading frames [ORFs]) isolated from a brain abscess in an infant. Comparative analysis of
S. intermedius
genome sequences suggested that TYG1620 carries a notable type VII secretion system (T7SS), two long repeat regions, and 19 ORFs for cell wall-anchored proteins (CWAPs). To elucidate the genes responsible for the pathogenicity of TYG1620, transcriptome analysis was performed in a murine subcutaneous abscess model. The results suggest that the levels of expression of small hypothetical proteins similar to phenol-soluble modulin β1 (PSMβ1), a staphylococcal virulence factor, significantly increased in the abscess model. In addition, an experiment in a murine subcutaneous abscess model with random transposon (Tn) mutant attenuation suggested that Tn mutants with mutations in 212 ORFs in the Tn mutant library were attenuated in the murine abscess model (629 ORFs were disrupted in total); the 212 ORFs are putatively essential for abscess formation. Transcriptome analysis identified 37 ORFs, including paralogs of the T7SS and a putative glucan-binding CWAP in long repeat regions, to be upregulated and attenuated
in vivo
. This study provides a comprehensive characterization of
S. intermedius
pathogenicity based on the complete genome sequence and a murine subcutaneous abscess model with transcriptome and Tn mutagenesis, leading to the identification of pivotal targets for vaccines or antimicrobial agents for the control of
S. intermedius
infections.
Characterization of Runella slithyformis HD-Pnk, a Bifunctional DNA/RNA End-Healing Enzyme Composed of an N-Terminal 2′,3′-Phosphoesterase HD Domain and a C-Terminal 5′-OH Polynucleotide Kinase Domain
Authors: Munir Annum , Shuman Stewart 
Published: November 2016

ABSTRACT

5′- and 3′-end-healing reactions are key steps in nucleic acid break repair in which 5′-OH ends are phosphorylated by a polynucleotide kinase (Pnk) and 3′-PO
4
or 2′,3′-cyclic-PO
4
ends are hydrolyzed by a phosphoesterase to generate the 5′-PO
4
and 3′-OH termini required for sealing by classic polynucleotide ligases. End-healing and sealing enzymes are present in diverse bacterial taxa, often organized as modular units within a single multifunctional polypeptide or as subunits of a repair complex. Here we identify and characterize
Runella slithyformis
HD-Pnk as a novel bifunctional end-healing enzyme composed of an N-terminal 2′,3′-phosphoesterase HD domain and a C-terminal 5′-OH polynucleotide kinase P-loop domain. HD-Pnk phosphorylates 5′-OH polynucleotides (9-mers or longer) in the presence of magnesium and any nucleoside triphosphate donor. HD-Pnk dephosphorylates RNA 2′,3′-cyclic phosphate, RNA 3′-phosphate, RNA 2′-phosphate, and DNA 3′-phosphate ends in the presence of a transition metal cofactor, which can be nickel, copper, or cobalt. HD-Pnk homologs are present in genera from 11 bacterial phyla and are often encoded in an operon with a putative ATP-dependent polynucleotide ligase.

IMPORTANCE
The present study provides insights regarding the diversity of nucleic acid repair strategies via the characterization of
Runella slithyformis
HD-Pnk as the exemplar of a novel clade of dual 5′- and 3′-end-healing enzymes that phosphorylate 5′-OH termini and dephosphorylate 2′,3′-cyclic-PO
4
, 3′-PO
4
, and 2′-PO
4
ends. The distinctive feature of HD-Pnk is its domain composition, i.e., a fusion of an N-terminal HD phosphohydrolase module and a C-terminal P-loop polynucleotide kinase module. Homologs of
Runella
HD-Pnk with the same domain composition, same domain order, and similar polypeptide sizes are distributed widely among genera from 11 bacterial phyla.