bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of halogen elements on the opening of an icosahedral B12 framework
Authors: Gong Liang-Fa , Li Wei , Osorio Edison , Wu Xin-Min , Heine Thomas , Liu Lei
Published: October 2017

The fully halogenated or hydrogenated B12X122− (X = H, F, Cl, Br and I) clusters are confirmed to be icosahedral. On the other hand, the bare B12 cluster is shown to have a planar structure. A previous study showed that a transformation from an icosahedron to a plane happens when 5 to 7 iodine atoms are remained [P. Farràs et al., Chem. - Eur. J. 18, 13208–13212 (2012)]. Later, the transition was confirmed to be seven iodine atoms based on an infrared spectroscopy study [M. R. Fagiania et al., Chem. Phys. Lett. 625, 48–52 (2015)]. In this study, we investigated the effects of different halogen atoms on the opening of the B12 icosahedral cage by means of density functional theory calculations. We found that the halogen elements do not have significant effects on the geometries of the clusters. The computed infrared (IR) spectra show similar representative peaks for all halogen doped clusters. Interestingly, we found a blue-shift in the IR spectra with the increase in the mass of the halogen atoms. Further, we compared the Gibbs free energies at different temperatures for different halogen atoms. The results show that the Gibbs free energy differences between open and close structures of B12X7− become larger when heavier halogen atoms are presented. This interesting finding was subsequently investigated by the energy decomposition analysis.
The effect of positively chirped laser pulse on energy enhancement of proton acceleration in combinational radiation pressure and bubble regime
Authors: Vosoughian H. , Sarri G. , Borghesi M. , Hajiesmaeilbaigi F. , Afarideh H.
Published: October 2017

Proton energy enhancement in a combinational radiation pressure and bubble regime by applying a positively chirped laser pulse has been studied using a series of two-dimensional particle-in-cell simulations. In this regime, the proton injection in the half-first period of an excited plasma wave in an under-dense plasma plays the main role in the acceleration process. Moreover, exciting as high as large-amplitude plasma waves can significantly increase the conversion efficiency of laser energy into kinetic energy of the trapped protons. Here, the utilization of the positively chirped laser pulse is proposed as an effective approach to excite the higher amplitude wake in the combinational regime. Our studies indicate that in the positively chirped combinational regime, the plasma wake with approximately two-fold enhancement is produced that results in the generation of the proton bunch with the narrower energy spread and also the peak enhancement by a factor of two, compared with the un-chirped one. This improvement in proton energy reveals that the chirped laser pulse can be introduced as a tool to tune the energy of generated protons in the combinational radiation pressure and bubble regime.
MoS2 nanosheet photodetectors with ultrafast response
Authors: Tang Weiwei , Liu Changlong , Wang Lin , Chen Xiaoshuang , Luo Man , Guo Wanlong , Wang Shao-Wei , Lu Wei
Published: October 2017

Two-dimensional layered materials, such as molybdenum disulfide, are emerging as an exciting material system for future electronics due to their unique electronic properties and atomically thin geometry. In this work, MoS2-based FETs are fabricated using mechanical cleavage and standard photolithographic and metal evaporation techniques, and the detector exhibits a good ohmic contact. We show that the multilayer molybdenum disulfide photodetector has a fast photoresponse as short as 42 μs. The fast photodetector response is due to the decrease in the trap states in MoS2 flakes compared to monolayer MoS2, making its photoresponse time close to its intrinsic response. The large photocurrent with the responsivity and external quantum efficiency of 59 A/W and 13 800% for the wavelength of 532 nm was also measured. The fast response time, high responsivity, and the ease of fabrication of these devices make them important components for future optoelectronic devices.
Coherence resonance in a network of FitzHugh-Nagumo systems: Interplay of noise, time-delay, and topology
Authors: Masoliver Maria , Malik Nishant , Schöll Eckehard , Zakharova Anna
Published: October 2017

We systematically investigate the phenomena of coherence resonance in time-delay coupled networks of FitzHugh-Nagumo elements in the excitable regime. Using numerical simulations, we examine the interplay of noise, time-delayed coupling, and network topology in the generation of coherence resonance. In the deterministic case, we show that the delay-induced dynamics is independent of the number of nearest neighbors and the system size. In the presence of noise, we demonstrate the possibility of controlling coherence resonance by varying the time-delay and the number of nearest neighbors. For a locally coupled ring, we show that the time-delay weakens coherence resonance. For nonlocal coupling with appropriate time-delays, both enhancement and weakening of coherence resonance are possible.
An evaluation of irreversible electroporation thresholds in human prostate cancer and potential correlations to physiological measurements
Authors: Campelo Sabrina , Valerio Massimo , Ahmed Hashim U. , Hu Yipeng , Arena Sara L. , Neal Robert E. , Emberton Mark , Arena Christopher B.
Published: October 2017

Irreversible electroporation (IRE) is an emerging cancer treatment that utilizes non-thermal electric pulses for tumor ablation. The pulses are delivered through minimally invasive needle electrodes inserted into the target tissue and lead to cell death through the creation of nanoscale membrane defects. IRE has been shown to be safe and effective when performed on tumors in the brain, liver, kidneys, pancreas, and prostate that are located near critical blood vessels and nerves. Accurate treatment planning and prediction of the ablation volume require a priori knowledge of the tissue-specific electric field threshold for cell death. This study addresses the challenge of defining an electric field threshold for human prostate cancer tissue. Three-dimensional reconstructions of the ablation volumes were created from one week post-treatment magnetic resonance imaging (MRIs) of ten patients who completed a clinical trial. The ablation volumes were incorporated into a finite element modeling software that was used to simulate patient-specific treatments, and the electric field threshold was calculated by matching the ablation volume to the field contour encompassing the equivalent volume. Solutions were obtained for static tissue electrical properties and dynamic properties that accounted for electroporation. According to the dynamic model, the electric field threshold was 506 ± 66 V/cm. Additionally, a potentially strong correlation (r = −0.624) was discovered between the electric field threshold and pre-treatment prostate-specific antigen levels, which needs to be validated in higher enrollment studies. Taken together, these findings can be used to guide the development of future IRE protocols.
Flexible and disposable paper- and plastic-based gel micropads for nematode handling, imaging, and chemical testing
Authors: Njus Zach , Kong Taejoon , Kalwa Upender , Legner Christopher , Weinstein Matthew , Flanigan Shawn , Saldanha Jenifer , Pandey Santosh
Published: October 2017

Today, the area of point-of-care diagnostics is synonymous with paper microfluidics where cheap, disposable, and on-the-spot detection toolkits are being developed for a variety of chemical tests. In this work, we present a novel application of microfluidic paper-based analytical devices (μPADs) to study the behavior of a small model nematode, Caenorhabditis elegans. We describe schemes of μPAD fabrication on paper and plastic substrates where membranes are created in agarose and Pluronic gel. Methods are demonstrated for loading, visualizing, and transferring single and multiple nematodes. Using an anthelmintic drug, levamisole, we show that chemical testing on C. elegans is easily performed because of the open device structure. A custom program is written to automatically recognize individual worms on the μPADs and extract locomotion parameters in real-time. The combination of μPADs and the nematode tracking program provides a relatively low-cost, simple-to-fabricate imaging and screening assay (compared to standard agarose plates or polymeric microfluidic devices) for non-microfluidic, nematode laboratories.
Observing propagating jet meanders in a numerical simulation of large-scale oceanic and atmospheric dynamics
Authors: Hendricks-Sturrup Rachele
Published: October 2017

Theoretical physicists investigate wavenumber-frequency spectra of various flow regimes using a simple numerical simulation model.
Influence of the on-line ELF-EMF stimulation on the electrophysiological properties of the rat hippocampal CA1 neurons in vitro
Authors: Zheng Yu , Ma Wei , Dong Lei , Dou Jun-rong , Gao Yang , Xue Jing
Published: October 2017

The extremely low frequency electromagnetic fields (ELF-EMFs) have been shown to have an environmentally negative effect on humans’ health; however, its treatment effect is beneficial for patients suffering from neurological disorders. Despite this success, the application of ELF-EMF has exceeded in the understanding of its internal mechanism. Recently, it was found that on-line magnetic stimulation may offer advantages over off-line magnetic exposure and has proven to be effective in activating the prefrontal cortex pyramidal neurons in vitro. Here, we perform computational simulations of the stimulation coils in COMSOL modeling to describe the uniformity of the distribution of the on-line magnetic field. Interestingly, the modeling data and actual measurements showed that the densities of the magnetic flux that was generated by the on-line stimulation coils were similar. The on-line magnetic stimulator induced sodium channel currents as well as field excitatory postsynaptic potentials of the rat hippocampal CA1 neurons and successfully demonstrated its extensive applications to activate neuronal tissue. These findings further raise the possibility that the instrument of on-line magnetic stimulation may be an effective alternative for studies in the field of bioelectromagnetics.
Calculation of thermodynamic properties and transport coefficients of C5F10O-CO2 thermal plasmas
Authors: Li Xingwen , Guo Xiaoxue , Murphy Anthony B. , Zhao Hu , Wu Jian , Guo Ze
Published: October 2017

The thermodynamic properties and transport coefficients of C5F10O-CO2 gas mixtures, which are being considered as substitutes for SF6 in circuit breaker applications, are calculated for the temperature range from 300 K to 30 000 K and the pressure range from 0.05 MPa to 1.6 MPa. Special attention is paid on investigating the evolution of thermophysical properties of C5F10O-CO2 mixtures with different mixing ratios and with different pressures; both the mixing ratio and pressure significantly affect the properties. This is explained mainly in terms of the changes in the temperatures at which the dissociation and ionization reactions take place. Comparisons of different thermophysical properties of C5F10O-CO2 mixtures with those of SF6 are also carried out. It is found that most of the thermophysical properties of the C5F10O-CO2 mixtures, such as thermal conductivity, viscosity, and electrical conductivity, become closer to those of SF6 as the C5F10O concentration increases. The composition and thermophysical properties of pure C5F10O in the temperature range from 300 K to 2000 K based on the decomposition pathway are also given. The calculation results provide a basis for further study of the insulation and arc-quenching capability of C5F10O-CO2 gas mixtures as substitutes for SF6.
Researchers use acoustic levitation to study charged liquid droplets splitting
Authors: Kim Meeri
Published: October 2017

German chemists combine field-induced drop ionization and acoustic levitation to expand research on charged liquid droplets.
Geometric confinement is required for recovery and maintenance of chondrocyte phenotype in alginate
Authors: Cooke Megan E. , Pearson Mark J. , Moakes Richard J. A. , Weston Christopher J. , Davis Edward T. , Jones Simon W. , Grover Liam M.
Published: October 2017

Human articular chondrocytes lose their native phenotype when expanded in traditional monolayer cultures. As a consequence, hydrogel encapsulation has been investigated as a means to maintain the natural phenotype. Alginate has been widely used for cartilage engineering as it has been shown to enable the recovery of a native collagen type II expressing chondrocyte phenotype. This study has evaluated whether the capacity of the materials to maintain/revert the phenotype is due to the composition of the material or the physical entrapment provided by the gel. To achieve this, an alginate “fluid gel” (a shear-thinning structured gel system) was produced of identical chemistry to a traditionally gelled alginate structure. Both were seeded with passaged primary human articular chondrocytes. Chondrocytes in quiescent alginate showed the recovery of the native phenotype and a spherical morphology. Chondrocytes in alginate fluid gel were unable to maintain the recovered phenotype despite having a spherical morphology and were shown to have a lower level of entrapment than those in quiescent alginate. These findings indicate that geometric entrapment is essential for the maintenance of a recovered chondrocyte phenotype in alginate.
Combining a topological insulator with a perpendicular magnetized ferromagnetic thin film
Authors: Cockbill Louisa
Published: October 2017

Researchers have demonstrated the successful growth of a BiSb/MnGa bilayer on GaAs despite crystal structure differences and lattice mismatches.
Evidence of evolutionary selection for cotranslational folding
Authors: Jacobs William M. , Shakhnovich Eugene I.
Published: October 2017

Significance

The mechanisms that affect protein production are crucially important but incompletely understood. In particular, the speed at which a polypeptide chain is synthesized can affect whether it folds to its native state. We propose that the optimal rate of translation depends on the sequence of stable conformations that are sampled by a nascent chain as it is being synthesized. Using optimal and rare synonymous codons as a proxy for translation speed, we find that transient pauses in synthesis are associated with specific intermediate conformations that appear during cotranslational folding and that this behavior is conserved across hundreds of genes and multiple prokaryotic genomes. These results provide striking evidence of evolutionary selection for efficient protein folding in vivo.
Configurational entropy measurements in extremely supercooled liquids that break the glass ceiling
Authors: Berthier Ludovic , Charbonneau Patrick , Coslovich Daniele , Ninarello Andrea , Ozawa Misaki , Yaida Sho
Published: October 2017

Significance

Computer simulations give precious insight into the microscopic behavior of disordered and amorphous materials, but the timescales they cover are orders of magnitude shorter than in experiments. For instance, simulations of glass-forming liquids cover at most 4–5 decades of viscous slowing down, which fall far short of the 12–13 decades commonly accessible in experimental studies. We here close this enormous gap for some realistic liquid models, and even equilibrate beyond experimental timescales by means of the swap Monte Carlo algorithm. We show that the approach to the glass phase is accompanied by a precipitous decrease of the configurational entropy as well as by growing spatial correlations, which we visualize in real space under experimentally relevant conditions.
Resistivity bound for hydrodynamic bad metals
Authors: Lucas Andrew , Hartnoll Sean A.
Published: October 2017

Significance

In conventional metals, momentum-relaxing scattering determines the electrical resistivity. In contrast, the resistivity of many strongly correlated metals, across multiple portions of their phase diagrams, is controlled by the electronic mean free path for momentum-conserving interactions

ρ

∝

1
/

ℓ
ee

. We propose that this universality arises in a hydrodynamic limit, where

ℓ
ee

is short. In this limit, we prove that the resistivity can be bounded by incoherent diffusion constants associated with momentum-conserving collisions. In the presence of a nonthermal incoherent diffusive mode—such as an imbalance mode for the charge in different Fermi bands—we find that saturation of our diffusion-limited transport bound implies

ρ

∝

1
/

ℓ
ee

, as observed in experiments.
The flexibility of the noun/verb distinction in the lexicon of Mandinka
Authors: Creissels Denis
Published: October 2017

In Mandinka, a Mande language, it is easy to identify words fulfilling the function of verbal head of a clause or nominal head of a noun phrase, but the division of lexemes into a class of nominal lexemes and a class of verbal lexemes is problematic, due to their categorial flexibility. This article argues that three major classes or lexemes must be distinguished: verbal lexemes (whose nominal use is fully predictable and can conveniently be analyzed as morphologically unmarked nominalization), nominal lexemes (whose verbal use is limited to the expression of ‘provide someone with X’), and verbo-nominal lexemes (whose nominal and verbal uses are equally productive, and at the same time cannot be related to each other by any general rule).
Polycategoriality and zero derivation
Authors: Mithun Marianne
Published: October 2017

The possibility of polycategorial lexical items, unspecified for category, raises interesting issues. One is the predictability of semantic relationships between polycategorial forms in predicating and referring uses. Another is the language-internal generality of the phenomenon, whether it necessarily holds of all units at a particular level. A third is its cross-linguistic generality and potential association with certain typological features. These issues are examined with examples from a language exhibiting striking similarities to the Mayan languages for which polycategoriality has recently been argued. Central Alaskan Yup’ik Eskimo appears to show robust polycategoriality at the root, stem, word, and clause level. A closer look indicates that the story is actually more interesting, and that the universality of polycategoriality remains an open question.
What determines constraints on the relationships between roots and lexical categories?
Authors: Haag Marcia
Published: October 2017

Evidence from Amerindian languages suggests that there are roots that have no inherent lexical category and roots that do. Both can co-exist in a single language. Acategorial roots, typical of Cherokee, have semantic content, but lexical category does not emerge until the level of the grammatical word. Words that share lexical roots are not predictable in their relationships. A different type of root, exemplified in Choctaw, places robust restrictions on its derivations. These roots predict not only a verb-noun correspondence, but also the semantic type of derivation. Nouns derived from verbs utilize the argument structure of the related verb to determine semantic type. Predicative roots with no argument structure have no predictable correspondences; those derivations are simply examples of conversion.
Lexical and syntactic categories in Nêlêmwa (New Caledonia) and some other Austronesian languages
Authors: Bril Isabelle
Published: October 2017

In contrast with various Austronesian languages (especially Formosan, Philippine, Polynesian) for which lexical roots are claimed to be functionally unspecified or precategorial, lexical bases in Nêlêmwa (New Caledonia) evidence a clear noun/verb opposition, identifiable by distinctive morphosyntactic features, except for some 5% fluid bases which can be nouns or verbs without any derivation. Beyond their prototypical functions, nouns, verbs and their subcategories display some functional flexibility in Nêlêmwa; it thus stands midway between flexible and rigid languages. Yet categorial flexibility is asymmetrical, nouns are the most flexible and may be recategorised in relation to their propositional operation and syntactic function, giving rise to hybrid lexico-syntactic words. Nêlêmwa data will be compared and put into perspective with data from other Austronesian languages.
Two classes of verbs in Northern Australian languages
Authors: Schultze-Berndt Eva
Published: October 2017

This paper discusses some of the implications for the typology of parts of speech – including the notion of polycategoriality – of the existence, in some Australian languages, of two clearly distinct lexical categories which meet the common definition of “verb”. Both appear exclusively in predicative function, but only one of them can form independent predicates, while the other is restricted to dependent predication. It is argued that the commonly assumed set of universal major parts of speech, even if conceived of as prototypes, is eurocentric and should be replaced by a more fine-grained set of syntacto-pragmatic functions which are better suited to identifying categorial overlap, and allow us to give proper consideration to more specialised parts of speech.
Word class distinctiveness versus polycategoriality in Modern Hebrew
Authors: Berman Ruth A.
Published: October 2017

The paper deals with word-formation devices in Modern Hebrew as reflecting word-class distinctiveness rather than polycategoriality, defined here as characterizing lexical items that share the same surface morpho-phonological form, yet function in different lexico-grammatical categories. Relevant typological features of the Modern Hebrew lexicon are outlined in terms of: the two major derivational processes of interdigitation of consonantal roots with affixal patterns and linear affixation to a stem; the relative morpho-phonological distinctiveness of the categories of N, V, and A; and the special status of benoni ‘intermediate’ participial forms as allowing polycategoriality in the shape of form-function shifts between these three lexical categories. Empirical evidence is then reviewed concerning preferred patterns of new-word formation in current Hebrew usage, and findings from structured elicitations and naturalistic speech samples are detailed for acquisition of word-class distinctions by pre-school Hebrew-speaking children, including the relatively minor role played by benoni polycategoriality in early child language. The concluding section discusses these findings in terms of the impact of linguistic typology and the lengthy developmental route in this, as in other domains, from initial non-analysis via morphological decomposition of lexical items and on to proficient, literacy-based construal of the elements constituting the mental lexicon.
Effect of a High Dosage Opioid Prior Authorization Policy on Prescription Opioid Use, Misuse, and Overdose Outcomes
Authors: Hartung Daniel M. , Kim Hyunjee , Ahmed Sharia M. , Middleton Luke , Keast Shellie , Deyo Richard A. , Zhang Kun , McConnell K. John
Published: October 2017

Background

High dosage opioid use is a risk factor for opioid-related overdose commonly cited in guidelines, recommendations, and policies. In 2012, the Oregon Medicaid program developed a prior authorization policy for opioid prescriptions above 120 mg per day morphine equivalent dose (MED). This study aimed to evaluate the effects of that policy on utilization, prescribing patterns, and health outcomes.

Methods

Using administrative claims data from Oregon and a control state (Colorado) between 2011 and 2013, we used difference-in-differences analyses to examine changes in utilization, measures of high risk opioid use, and overdose after introduction of the policy. We also evaluated opioid utilization in a cohort of individuals who were high dosage opioid users before the policy.

Results

Following implementation of Oregon's high dosage policy, the monthly probability of an opioid fill over 120 mg MED declined significantly by 1.7 percentage points (95% confidence interval [CI]; -2.0% to -1.4%), whereas it increased significantly by 1.0 percentage points (95% CI 0.4% to 1.7%) for opioid fills < 61 mg MED. Fills of medications used to treat neuropathic pain also increased by 1.2 percentage points (95% CI 0.7% to 1.8%). The monthly probability of multiple pharmacy use declined by 0.1 percentage points (-0.2% to -0.0) following the prior authorization, but there were no significant changes in ED encounters or hospitalizations for opioid overdose. Among individuals who were using a high dosage opioid before the policy, there was a 20.3 percentage point (95% CI -15.3% to -25.3%) decline in estimated probability of having a high dosage fill after the policy.

Conclusions

Oregon's prior authorization policy was effective at reducing high dosage opioid prescriptions. While multiple pharmacy use also declined, we found no impact on opioid overdose were observed.
MATAM: reconstruction of phylogenetic marker genes from short sequencing reads in metagenomes
Authors: Pericard Pierre , Dufresne Yoann , Couderc Loïc , Blanquart Samuel , Touzet Hélène
Published: October 2017

Motivation

Advances in the sequencing of uncultured environmental samples, dubbed metagenomics, raise a growing need for accurate taxonomic assignment. Accurate identification of organisms present within a community is essential to understanding even the most elementary ecosystems. However, current high-throughput sequencing technologies generate short reads which partially cover full-length marker genes and this poses difficult bioinformatic challenges for taxonomy identification at high resolution.

Results

We designed MATAM, a software dedicated to the fast and accurate targeted assembly of short reads sequenced from a genomic marker of interest. The method implements a stepwise process based on construction and analysis of a read overlap graph. It is applied to the assembly of 16S rRNA markers and is validated on simulated, synthetic and genuine metagenomes. We show that MATAM outperforms other available methods in terms of low error rates and recovered fractions and is suitable to provide improved assemblies for precise taxonomic assignments.

Availability and implementation

https://github.com/bonsai-team/matam

Supplementary information

Supplementary data are available at Bioinformatics online.
Boundary Behaviour of Weil–Petersson and Fibre Metrics for Riemann Moduli Spaces
Authors: Melrose Richard , Zhu Xuwen
Published: October 2017

The Weil–Petersson and Takhtajan–Zograf metrics on the Riemann moduli spaces of complex structures for an $n$-fold punctured oriented surface of genus $g,$ in the stable range $g+2n>2,$ are shown here to have complete asymptotic expansions in terms of Fenchel–Nielsen coordinates at the exceptional divisors of the Knudsen–Deligne–Mumford compactification. This is accomplished by finding a full expansion for the hyperbolic metrics on the fibres of the universal curve as they approach the complete metrics on the nodal curves above the exceptional divisors and then using a push-forward theorem for conormal densities. This refines a two-term expansion due to Obitsu–Wolpert for the conformal factor relative to the model plumbing metric which in turn refined the bound obtained by Masur. A similar expansion for the Ricci metric is also obtained.
The Impact of Human Pegivirus on CD4 Cell Count in HIV-Positive Persons in Botswana
Authors: N’Guessan Kombo F , Anderson Motswedi , Phinius Bonolo , Moyo Sikhulile , Malick Alyyah , Mbangiwa Tshepiso , Choga Wonderful T , Makhema Joseph , Marlink Richard , Essex Max , Musonda Rosemary , Gaseitsiwe Simani , Blackard Jason T
Published: October 2017

Background

Human pegiviruses (HPgV)—formerly known as hepatitis G virus or GB virus C (GBV-C)—are common single-stranded RNA viruses that may have a beneficial impact on slowing HIV disease progression. The data on HPgV in resource-limited regions such as Sub-Saharan Africa are scarce. Thus, we conducted the first study of HPgV in Botswana as part of a natural history study of HIV subtype C disease progression.

Methods

Plasma samples from 133 HIV-positive adults were evaluated for HPgV RNA, and the 5’UTR was sequenced to determine the HPgV genotype.

Results

HPgV RNA was detected in 41 (30.8%) individuals. While the presence of HPgV RNA had no impact on baseline HIV viral load, a significant difference in baseline CD4 cell count was observed. HPgV genotypes were determined for 27 individuals and included 5 individuals (18.5%) with genotype 1 and 22 (81.5%) with genotype 5. Baseline CD4 cell counts were significantly higher for persons infected with HPgV genotype 5 compared with genotype 1.

Conclusions

These data suggest that HPgV infection is common among HIV-positive individuals in Botswana and has a significant impact on CD4 cell count. This difference in CD4 cell count based on HPgV genotype suggests that HPgV genotype should be evaluated as a possible predictor of HIV disease progression and highlights the need for additional studies of this virus in resource-limited settings.
Clinical Outcome after Endoscopic Endonasal Resection of Tuberculum Sella Meningiomas
Authors: Elshazly Khaled , Kshettry Varun R , Farrell Christopher J , Nyquist Gurston , Rosen Marc , Evans James J
Published: October 2017

BACKGROUND

In select cases, the endoscopic endonasal approach (EEA) has distinct advantages for resection of tuberculum sella meningiomas (TSM).

OBJECTIVE

To report the extent of resection (EOR), complication rates, and outcomes in a large series of TSM treated by the EEA.

METHODS

Twenty-five consecutive TSM cases treated by EEA from 2008 to 2016 were retrospectively reviewed. Patient history, imaging, volumetric EOR, complications, and outcomes are presented.

RESULTS

Mean patient age was 53.9 yr, with female predominance (84%). Preoperatively, 84% of patients had vision impairment and 68% had optic canal tumor invasion. The tumor was abutting or partially encasing the anterior cerebral artery in 14 (56%) and 3 (12%) patients, respectively. The supraclinoid internal carotid artery (ICA) was partially or completely encased in 4 (16%) and 4 (16%) patients, respectively. Gross total resection (GTR) was achieved in 19/25 (76%) cases. Complete ICA encasement was the most common reason for subtotal resection. Among patients without complete ICA encasement, GTR was achieved in 19/20 (95%) patients. Optic canal invasion, tumor volume, intratumoral calcifications, and partial vascular encasement were not limiting factors for GTR. Eighty-eight percent of patients with preoperative visual impairment had improvement or normalization of vision. No patient experienced permanent visual deterioration or new permanent pituitary dysfunction. Cerebrospinal fluid leakage occurred in 2 (8%) cases.

CONCLUSION

The EEA for resection of TSM provides high rates of GTR and visual improvement with a low rate of complications. Direct contact or partial encasement of the ICA and anterior cerebral artery does not limit the EOR.
Multimodality Management of Recurrent Skull Base Chordomas: Factors Impacting Tumor Control and Disease-Specific Survival
Authors: Raza Shaan M , Bell Diana , Freeman Jacob L , Grosshans David R , Fuller Gregory N , DeMonte Franco
Published: October 2017

BACKGROUND

Limited data exist to guide the management of recurrent chordomas arising in the skull base.

OBJECTIVE

To determine factors affecting tumor control rates and disease-specific survival (DSS) in recurrent disease.

METHODS

A retrospective review was performed of 29 patients with 55 recurrences treated at our institution. Tumor and treatment factors were assessed for impact on freedom from progression (FFP; primary outcome) and DSS (secondary outcome).

RESULTS

Postradiotherapy disease failure was much more difficult to manage vs progression after surgery alone (15.9 vs 41.4 mo, P = .094). Distant metastases and, specifically, leptomeningeal disease at presentation were associated with poorer DSS and FFP (P < .05). For local progression after surgery alone, repeat resection (P < .05) improved median FFP. With postradiotherapy local failure, repeat resection did not confer any benefit (13.5 vs 17.6 mo, P > .05), while a trend towards improved FFP was seen with stereotactic radiosurgery (28.3 vs 16.2 mo, P = .233). For distant metastases, site-directed therapy (surgery or radiation) allowed for site control (P < .05) but did not affect FFP or DSS. Presentation with early progression <6 mo from previous treatment portended significantly worse DSS (19.3 vs 77.6 mo, P < .05).

CONCLUSION

There is a need for treatment of recurrent disease to be tailored to the pattern of tumor recurrence and previously received treatments. Postradiotherapy progression poses particular challenges given the apparent limited role of repeat resection alone. Stereotactic radiosurgery may have a role in this setting. While patients with systemic metastases appear to respond well to site-directed therapy, those with leptomeningeal disease have a dismal prognosis.
Genetic Diversity of Fusarium oxysporum f. sp. cubense in East and Central Africa
Authors: Karangwa Patrick , Mostert Diane , Ndayihanzamaso Privat , Dubois Thomas , Niere Björn , zum Felde Alexandra , Schouten Alexander , Blomme Guy , Beed Fenton , Viljoen Altus
Published: October 2017

Banana Fusarium wilt is a major production constraint globally and a significant threat to the livelihoods of millions of people in East and Central Africa (ECA). A proper understanding of the diversity and population dynamics of the causal agent, Fusarium oxysporum f. sp. cubense (Foc), could be useful for the development of sustainable disease management strategies for the pathogen. The current study investigated the diversity of Foc in ECA using vegetative compatibility group (VCG) analysis, PCR-RFLPs of the ribosomal DNA’s intergenic spacer region, as well as phylogenetic analysis of the elongation factor-1α gene. Six VCGs (0124, 0125, 0128, 01212, 01220, and 01222), which all belong to one lineage (Foc lineage VI), were widely distributed throughout the region. VCGs 0128 and 01220 are reported for the first time in Burundi, the Democratic Republic of Congo (DRC), Rwanda, Tanzania, and Uganda, while VCG 01212 is reported in the DRC and Rwanda. Isolates that did not belong to any of the known VCGs were identified as Foc lineage VI members by phylogenetic analysis and may represent novel VCGs. CAV 2734, a banana pathogen collected in Rwanda, clustered with nonpathogenic F. oxysporum isolates in lineage VIII. Results from this study will contribute significantly toward the implementation of banana Fusarium wilt disease management practices in the region, such as the restricted movement of infected planting material and the selective planting of resistant banana varieties.
The Relationship Between Posttraumatic Stress Disorder and Chronic Pain in People Seeking Treatment for Chronic Pain
Authors: Åkerblom Sophia , Perrin Sean , Rivano Fischer Marcelo , McCracken Lance M.
Published: October 2017

Objectives:

The symptoms of posttraumatic stress disorder (PTSD) and chronic pain are thought to interact to increase the severity and impact of both conditions, but the mechanisms by which they interact remain unclear. This study examines the relationship between PTSD and chronic pain and whether indices of Psychological Flexibility mediate the relationship between these 2 conditions.

Materials and Methods:

Standardized self-report measures of PTSD, pain severity, pain interference, depression, and psychological flexibility (pain-related acceptance, committed action, cognitive fusion, and values-based action) were obtained from 315 people seeking treatment for chronic pain who also reported at least 1 traumatic experience.

Results:

People seeking treatment for chronic pain and reporting symptoms consistent with a current diagnosis of PTSD had significantly higher levels of pain severity, pain interference, depression, and cognitive fusion and lower levels of pain-related acceptance and committed action than those reporting symptoms below the diagnostic threshold for PTSD. Pain-related acceptance, committed action, cognitive fusion, and depression mediated the relationship between PTSD and pain severity/interference, with pain-related acceptance being the strongest mediator from the Psychological Flexibility model.

Discussion:

Processes from the Psychological Flexibility model were identified as mediators of the relationship between PTSD and chronic pain in people seeking treatment for chronic pain. The Psychological Flexibility model may be useful as an overarching model to help understand the relationship between PTSD and chronic pain. It is possible that targeting pain-related acceptance, committed action, and cognitive fusion (among other processes) in the treatment of chronic pain may produce corresponding improvements in comorbid symptoms of PTSD when these are present and may reduce impacts of PTSD on outcomes of chronic pain. Conversely, targeting of these processes in the treatment of PTSD may produce similar improvements for symptoms of chronic pain. Further research to evaluate these possibilities is needed.
Accuracy of Four Imaging Techniques for Diagnosis of Posterior Pelvic Floor Disorders
Authors: van Gruting Isabelle M. A. , Stankiewicz Aleksandra , Kluivers Kirsten , De Bin Riccardo , Blake Helena , Sultan Abdul H. , Thakar Ranee
Published: October 2017

OBJECTIVE:

To establish the diagnostic test accuracy of evacuation proctography, magnetic resonance imaging (MRI), transperineal ultrasonography, and endovaginal ultrasonography for detecting posterior pelvic floor disorders (rectocele, enterocele, intussusception, and anismus) in women with obstructed defecation syndrome and secondarily to identify the most patient-friendly imaging technique.

METHODS:

In this prospective cohort study, 131 women with symptoms of obstructed defecation syndrome underwent evacuation proctogram, MRI, and transperineal and endovaginal ultrasonography. Images were analyzed by two blinded observers. In the absence of a reference standard, latent class analysis was used to assess diagnostic test accuracy of multiple tests with area under the curve (AUC) as the primary outcome measure. Secondary outcome measures were interobserver agreement calculated as Cohen's κ and patient acceptability using a visual analog scale.

RESULTS:

No significant differences in diagnostic accuracy were found among the imaging techniques for all the target conditions. Estimates of diagnostic test accuracy were highest for rectocele using MRI (AUC 0.79) or transperineal ultrasonography (AUC 0.85), for enterocele using transperineal (AUC 0.73) or endovaginal ultrasonography (AUC 0.87), for intussusception using evacuation proctography (AUC 0.76) or endovaginal ultrasonography (AUC 0.77), and for anismus using endovaginal (AUC 0.95) or transperineal ultrasonography (AUC 0.78). Interobserver agreement for the diagnosis of rectocele (κ 0.53–0.72), enterocele (κ 0.54–0.94) and anismus (κ 0.43–0.81) was moderate to excellent, but poor to fair for intussusception (κ −0.03 to 0.37) with all techniques. Patient acceptability was better for transperineal and endovaginal ultrasonography as compared with MRI and evacuation proctography (P<.001).

CONCLUSION:

Evacuation proctography, MRI, and transperineal and endovaginal ultrasonography were shown to have similar diagnostic test accuracy. Evacuation proctography is not the best available imaging technique. There is no one optimal test for the diagnosis of all posterior pelvic floor disorders. Because transperineal and endovaginal ultrasonography have good test accuracy and patient acceptability, we suggest these could be used for initial assessment of obstructed defecation syndrome.

CLINICAL TRIAL REGISTRATION:

ClinicalTrials.gov, NCT02239302.
Epidural Analgesia During the Second Stage of Labor
Authors: Shen XiaoFeng , Li Yunping , Xu ShiQin , Wang Nan , Fan Sheng , Qin Xiang , Zhou Chunxiu , Hess Philip E.
Published: October 2017

OBJECTIVE:

To evaluate whether maintaining a motor-sparing epidural analgesia infusion affects the duration of the second stage of labor in nulliparous parturients compared with a placebo control.

METHODS:

We conducted a double-blind, randomized, placebo-controlled trial involving nulliparous women with term cephalic singleton pregnancies who requested epidural analgesia. All women received epidural analgesia for the first stage of labor using 0.08% ropivacaine with 0.4 micrograms/mL sufentanil with patient-controlled epidural analgesia. At the onset of the second stage of labor, women were randomized to receive a blinded infusion of the same solution or placebo saline infusion. The primary outcome was the duration of the second stage of labor. A sample size of 200 per group (400 total) was planned to identify at least a 15% difference in duration.

RESULTS:

Between March 2015 and September 2015, 560 patients were screened and 400 patients (200 in each group) completed the study. Using an intention-to-treat analysis, the duration of the second stage was similar between groups (epidural 52±27 minutes compared with saline 51±25 minutes, P=.52). The spontaneous vaginal delivery rate was also similar (epidural 193 [96.5%] compared with saline 198 [99%], P=.17). Pain scores were similar between groups at each measurement during the second stage. More women who received placebo reported satisfaction scores of 8 or less (epidural 32 [16%] compared with saline 61 [30.5%], P=.001).

CONCLUSION:

Maintaining the infusion of epidural medication had no effect on the duration of the second stage of labor compared with a placebo infusion. Maternal and neonatal outcomes were similar. A low concentration of epidural local anesthetic does not affect the duration of the second stage of labor.

CLINICAL TRIAL REGISTRATION:

Chinese Clinical Trial Register, http://www.chictr.org.cn/enindex.aspx, ChiCTR-IOR-15005875.
Change in Surgical Practice for Women With Leiomyomas After the U.S. Food and Drug Administration Morcellator Safety Communication
Authors: Clark Nina M. , Schembri Michael , Jacoby Vanessa L.
Published: October 2017

OBJECTIVE:

To evaluate the association between the U.S. Food and Drug Administration (FDA) communication discouraging use of power morcellators on changes in surgical practice for women with uterine leiomyomas.

METHODS:

This is a cross-sectional study using data from 2013 to 2014 in the Healthcare Cost and Utilization Project State Inpatient and State Ambulatory Surgical Databases from Arizona, Florida, Kentucky, and New Jersey. Women with a diagnosis of leiomyomas who underwent hysterectomy or myomectomy were included in the analysis. Multivariable models were used to assess changes in the proportion of hysterectomies performed laparoscopically, vaginally, or by laparotomy in the 15 months before the FDA safety communication in April 2013 (January 2013 to March 2014) to the 9 months after the FDA communication (April to December 2014). Changes in the proportion of women who underwent myomectomy compared with hysterectomy were also evaluated during this time period.

RESULTS:

There were 77,637 hysterectomy and myomectomy cases analyzed from states with both inpatient and ambulatory surgery data; 59% of patients were outpatients. Overall, there was a 4% (95% CI 3.2–4.8%) decrease in the use of laparoscopic hysterectomy for treatment of uterine leiomyomas from 62% of all hysterectomies before the FDA communication on morcellation to 58% afterward. Changes in surgical practice were more pronounced in the inpatient compared with outpatient setting; inpatient laparoscopic hysterectomy decreased by 7% (95% CI 6.1–7.9%) from 24% to 17% of all hysterectomies with an accompanying increase in abdominal hysterectomy of 8% (95% CI 6.7–8.6%) from 71% to 79%. There were no significant changes in the proportion of women with leiomyomas who underwent myomectomy compared with hysterectomy.

CONCLUSION:

The FDA communication discouraging the use of power morcellators was associated with a decline in laparoscopy to perform hysterectomy, particularly in the inpatient setting. There was no change in the selection of myomectomy compared with hysterectomy for leiomyoma treatment after the FDA communication.
Leiomyomas in Pregnancy and Spontaneous Abortion
Authors: Sundermann Alexandra C. , Velez Edwards Digna R. , Bray Michael J. , Jones Sarah H. , Latham Sanura M. , Hartmann Katherine E.
Published: October 2017

OBJECTIVE:

To systematically review studies reporting the risk of spontaneous abortion among pregnant women of typical reproductive potential with and without uterine leiomyomas.

DATA SOURCES:

We searched PubMed, EMBASE, Web of Science, and ClinicalTrials.gov for publications from January 1970 to December 2016.

METHODS OF STUDY SELECTION:

We excluded studies that did not use imaging to uniformly document leiomyoma status of all participants, did not have a comparison group without leiomyomas, or primarily included women seeking care for recurrent miscarriage, infertility care, or assisted reproductive technologies.

TABULATION, INTEGRATION, AND RESULTS:

Two authors independently reviewed eligibility, extracted data, and assigned overall quality ratings based on predetermined criteria. Of 1,469 articles identified, nine were eligible. Five enrolled general obstetric populations and four included women undergoing amniocentesis. In five studies in general obstetric populations that included 21,829 pregnancies (1,394 women with leiomyomas and 20,435 without), only one adjusted for potential confounders. This meta-analysis revealed no increase in risk of spontaneous abortion among those with leiomyomas compared with those without (11.5% compared with 8.0%; risk ratio 1.16, 95% CI 0.80–1.52). When bias from confounding was estimated for nonadjusted studies, the aggregate calculated risk ratio was 0.83 (95% CI 0.68–0.98).

CONCLUSION:

Leiomyoma presence was not associated with increased risk of spontaneous abortion in an analysis of more than 20,000 pregnant women. Failure of prior studies to adjust for confounders may have led to the common clinical belief that leiomyomas are a risk factor for spontaneous abortion.