bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modulation of Kinetic Pathways of Enzyme–Substrate Interaction in a Microfluidic Channel: Nanoscopic Water Dynamics as a Switch
Authors: Singh Priya , Mukherjee Dipanjan , Singha Subhankar , Das Ranjan , Pal Samir Kumar 
Published: May 2019

AbstractEnzyme‐mediated catalysis is attributed to enzyme–substrate interactions, with models such as “induced fit” and “conformational selection” emphasizing the role of protein conformational transitions. The dynamic nature of the protein structure, thus, plays a crucial role in molecular recognition and substrate binding. As large‐scale protein motions are coupled to water motions, hydration dynamics play a key role in protein dynamics, and hence, in enzyme catalysis. Here, microfluidic techniques and time‐dependent fluorescence Stokes shift (TDFSS) measurements are employed to elucidate the role of nanoscopic water dynamics in the interaction of an enzyme, α‐Chymotrypsin (CHT), with a substrate, Ala‐Ala‐Phe‐7‐amido‐4‐methylcoumarin (AMC) in the cationic reverse micelles of benzylhexadecyldimethylammonium chloride (BHDC/benzene) and anionic reverse micelles of sodium bis(2‐ethylhexyl)sulfosuccinate (AOT/benzene). The kinetic pathways unraveled from the microfluidic setup are consistent with the “conformational selection” fit for the interaction of CHT with AMC in the cationic reverse micelles, whereas an “induced fit” mechanism is indicated for the anionic reverse micelles. In the cationic reverse micelles of BHDC, faster hydration dynamics (≈550 ps) aid the pathway of “conformational selection”, whereas in the anionic reverse micelles of AOT, the significantly slower dynamics of hydration (≈1600 ps) facilitate an “induced fit” mechanism for the formation of the final enzyme–substrate complex. The role of water dynamics in dictating the mechanism of enzyme–substrate interaction becomes further manifest in the neutral reverse micelles of Brij‐30 and Triton X‐100. In the former, the faster water dynamics aid the “conformational selection” pathway, whereas the significantly slower dynamics of water molecules in the latter are conducive to the “induced fit” mechanism in the enzyme–substrate interaction. Thus, nanoscopic water dynamics act as a switch in modulating the pathway of recognition of an enzyme (CHT) by the substrate (AMC) in reverse micelles.
Enantio‐ and Diastereoswitchable C−H Arylation of Methylene Groups in Cycloalkanes
Authors: Andrä Michal S. , Schifferer Lukas , Pollok Corina H. , Merten Christian , Gooßen Lukas J. , Yu Jin‐Quan 
Published: May 2019

AbstractA complementary set of chiral N,N‐ligands enables the Pd‐catalyzed β‐C−H arylation of unbiased internal methylene groups in good yield and with high levels of enantio‐ and diastereoinduction. Both the dia‐ and enantioselectivity can be reversed, thus allowing the selective arylation of any of the four β‐C−H bonds in cycloalkanecarboxamides of various ring sizes. The method is applicable to a broad range of aryl iodides with electron‐withdrawing and ‐donating substituents in theo‐,m‐, orp‐position.
A novel phase field method for modeling the fracture of long bones
Authors: Shen Rilin , Waisman Haim , Yosibash Zohar , Dahan Gal 
Published: May 2019

AbstractA proximal humerus fracture is an injury to the shoulder joint that necessitates medical attention. While it is one of the most common fracture injuries impacting the elder community and those who suffer from traumatic falls or forceful collisions, there are almost no validated computational methods that can accurately model these fractures. This could be due to the complex, inhomogeneous bone microstructure, complex geometries, and the limitations of current fracture mechanics methods.In this paper, we develop a novel phase field method to investigate the proximal humerus fracture. To model the fracture in the inhomogeneous domain, we propose a power‐law relationship between bone mineral density and critical energy release rate. The method is validated by an in vitro experiment, in which a human humerus is constrained on both ends while subjected to compressive loads on its head, in the longitudinal direction, that lead to fracture at the anatomical neck. CT scans are employed to acquire the bone geometry and material parameters, from which detailed finite element meshes with inhomogeneous Young modulus distributions are generated.The numerical method, implemented in a high performance computing environment, is used to quantitatively predict the complex 3D brittle fracture of the bone and is shown to be in good agreement with experimental observations. Furthermore, our findings show that the damage is initiated in the trabecular bone‐head and propagates outward towards the bone cortex. We conclude that the proposed phase field method is a promising approach to model bone fracture.
Nonadiabatic Dynamics Simulation Predict Intersystem Crossing in Nitroaromatic Molecules on a Picosecond Time Scale
Authors: Zobel J. Patrick , González Leticia 
Published: May 2019

AbstractPrevious time‐resolved spectroscopic experiments and static quantum‐chemical calculations attributed nitronaphthalene derivatives one of the fastest time scales for intersystem crossing within organic molecules, reaching the 100 fs mark. Nonadiabatic dynamics simulations on three nitronaphthalene derivatives challenge this view, showing that the experimentally observed ∼100 fs process corresponds to internal conversion in the singlet manifolds. Intersystem crossing, instead, takes place on a longer time scale of ∼1 ps. The dynamics simulations further reveal that the spin transitions occur via two distinct pathways with different contribution for the three systems, which are determined by electronic factors and the torsion of the nitro group. This study, therefore, indicates that the existence of sub‐picosecond intersystem crossing in other nitroaromatic molecules should be questioned.
Layered Confinement Reaction: Atomic‐level Dispersed Iron–Nitrogen Co‐Doped Ultrathin Carbon Nanosheets for CO2 Electroreduction
Authors: Tuo Jinqin , Zhu Yihua , Cheng Ling , Li Yuhang , Yang Xiaoling , Shen Jianhua , Li Chunzhong 
Published: May 2019

AbstractHigh electrochemical over‐potential and low product selectivity are regarded as the main limitations of electroreduction of CO2. Here, we proposed a new strategy to synthesize metal porphyrin‐hybridized porous and ultra‐thin carbon nanosheets (MPPCN) by the confinement function of the layered template. The layered confinement reaction protects the coordination structure of metal and nitrogen atoms during subsequent high‐temperature treatment while ensuring the formation of ultra‐thin structures. This method effectively prevents the aggregation of metal atoms, so that the metal atoms exhibit a dispersed state of a single atomic level. MPPCN exhibit unexpected catalytic activity for electroreduction of CO2, and the catalytic reaction can be carried out at an over‐potential of 0.39 V. The faradaic efficiency of CO can reach 95.9 % at the potential of −0.7 V versus the reversible hydrogen electrode.
The ecological significance of extremely large flocks of birds
Authors: Møller Anders Pape , Laursen Karsten 
Published: May 2019

AbstractPopulation size is generally limited by resource availability during and outside the breeding season. Therefore, maximum size of flocks may provide important information on population regulation and the influence of diet and trophic level on maximal degree of sociality. We hypothesized that (a) flock size should increase with nutrient availability; (b) flock size should decrease with latitude because productivity is higher at lower latitude; (c) aquatic habitats should have larger flocks than terrestrial habitats because the former are less accessible; (d) smaller species should have larger flocks because they require overall less food; (e) human‐impacted species that live in perturbed habitats should have smaller flocks than other species; (f) flock size should decrease with increasing trophic level because there is a reduction in biomass due to conversion at each trophic level; and (g) flocks of species depending on ancestral landscapes should have decreased in size in recent years due to human impact (e.g., land‐use). We obtained 1564 observations of flocks that exceeded 100,000 individuals in order to test the predictions listed above. Most effect sizes were small to medium accounting for 1%–9% of the variance, while large effects accounting for 25% or more were only found for total nitrogen used per km2 and area used for agriculture. Changes in large bird flocks were caused by habitat degradation and persecution, and temporal decline in size of large flocks revealed changes in nutrient use, reductions in nutrient cycling, and changes in flock size linked to trophic level.
Construction of novel silicon‐phosphorus linear polymers with DDSQ and DOPO derivatives for effective flame retardancy of PC/ABS
Authors: Song Wenpeng , Zhang Wang , Li Yonggang , Ma Huijuan , Lin Tao , Lu Cuifen , Nie Junqi , Yang Guichun , Chen Zuxing 
Published: May 2019

SummaryTwo kinds of novel silicon‐phosphorus linear polymers were synthesized by the hydrosilylation reaction of double‐decker‐shaped silsesquioxane (DDSQ) and 9,10‐dihydro‐9‐oxa‐10‐ phosphaphenanthrene‐10‐oxide (DOPO) derivatives and characterized using 1H NMR, 31P NMR, and 29Si NMR. Flame‐retardant polycarbonate/acrylonitric‐butadiene‐styrene (PC/ABS) blends were prepared with different contents of silicon‐phosphorus linear polymers. The flame‐retardant properties of silicon‐phosphorus linear polymers as well as the morphology were investigated in detail by using thermogravimetric analysis (TGA), limiting oxygen index (LOI), (Underwriters Laboratory) UL‐94, microscale combustion calorimetry (MCC), and scanning electron microscopy (SEM), respectively. The silicon‐phosphorus linear polymers containing DDSQ and DOPO units can synergistically improve the flame retardancy and thermal stability of PC/ABS blends. Flame‐retardant polymers with different linkers between DDSQ and phosphate units show comparable effect on the flame retardancy of PC/ABS.
Survivin a pivotal antiapoptotic protein in rheumatoid arthritis
Authors: Zafari Parisa , Rafiei Alireza , Esmaeili Seyed‐Alireza , Moonesi Mohammadreza , Taghadosi Mahdi 
Published: May 2019

AbstractRheumatoid arthritis (RA) is an autoimmune disease, pathologically characterized by lymphocyte infiltration of the synovial membrane that leads to chronic inflammation and progressive joint damage. RA develops as a result of increased cell infiltration and cell proliferation as well as impaired cell death. Activated cells in joints including lymphocytes and fibroblast‐like synoviocytes (FLS) survive for a long time as a consequence of compromised apoptosis, but the mechanism underlying cell survival in synovium remains to be firmly established. Inhibition of apoptosis by survivin, as a critical antiapoptotic protein, contributes to both the persistence of autoreactive T lymphocytes and tumor‐like phenotype of FLS in RA. In addition to the antiapoptotic role, survivin also has prognostic relevance in RA prodromal phase. Hence, this review provides an overview of the current knowledge regarding the involvement of survivin protein in the pathogenesis of RA.
Viral receptors for flaviviruses: Not only gatekeepers
Authors: Oliveira Lilian G , Peron Jean Pierre Schatzmann 
Published: May 2019

AbstractArboviruses have been a huge threat for human health since the discovery of yellow fever virus in 1901. Arboviruses are arthropod born viruses, mainly transmitted by mosquitoes and ticks, responsible for more than thousands of deaths annually. The Flavivirideae family is probably the most clinically relevant, as it is composed of very important agents, such as dengue, yellow fever, West Nile, Japanese encephalitis, and, recently, Zika virus. Intriguingly, despite their structural and genomic similarities, flaviviruses may cause conditions ranging from mild infections with fever, cutaneous rash, and headache, to very severe cases, such as hemorrhagic fever, encephalitis, Guillain-Barré syndrome, and microcephaly. These differences may greatly rely on viral burden, tissue tropism, and mechanisms of immune evasion that may depend on both viral and host genetic factors. Unfortunately, very little is known about the biology of these factors, and how they orchestrate these differences. In this context, viral structural proteins and host cellular receptors may have a great relevance, as their interaction dictates not only viral tissue tropism, but also a plethora on intracellular mechanisms that may greatly account for either failure or success of infection. A great number of viral receptors have been described so far, although there is still a huge gap in understanding their overall role during infection. Here we discuss some important aspects triggered after the interaction of flaviviruses and host membrane receptors, and how they change the overall outcome of the infection.
The impact of chemotherapy sequence on survival in node‐positive invasive lobular carcinoma
Authors: Tamirisa Nina , Williamson Hannah V. , Thomas Samantha M. , Westbrook Kelly E. , Greenup Rachel A. , Plichta Jennifer K. , Rosenberger Laura H. , Hyslop Terry , Hwang Eun‐Sil Shelley , Fayanju Oluwadamilola M. 
Published: May 2019

AbstractBackground and ObjectivesWe sought to evaluate the impact of chemotherapy sequence on survival by comparing node‐positive invasive lobular carcinoma (ILC) patients who received neoadjuvant (NACT) and adjuvant (ACT) chemotherapy.MethodscT1‐4c, cN1‐3 ILC patients in the National Cancer Data Base (2004‐2013) who underwent surgery and chemotherapy were divided into NACT and ACT cohorts. Kaplan‐Meier curves and Cox proportional hazards modeling were used to estimate unadjusted and adjusted overall survival (OS), respectively.ResultsFive thousand five hundred fifty‐one (35.6%) of 15 573 ILC patients treated with chemotherapy received NACT. NACT patients had similar rates of pT3/4 disease (26.6% vs 26.2%), nodal involvement (median 3 vs 4), and number of lymph nodes examined (median 13 vs 14) but higher rates of mastectomy (81.8% vs 74.5%, P < 0.001) vs ACT patients. 3.4% of NACT patients experienced pathologic complete response (pCR). Unadjusted 10‐year OS was worse for NACT vs ACT patients (65.1% vs 54.4%, log‐rank P < 0.001). After adjustment for known covariates, NACT continued to be associated with worse OS (hazard ratio [HR], 1.38; 95% confidence interval [CI], 1.25‐1.52).ConclusionsIn node‐positive ILC, NACT yielded low rates of pCR, was not associated with lower rates of mastectomy or less extensive axillary surgery, and was associated with worse survival vs ACT, suggesting limited benefit for these patients.
Impact of hypofractionated schemes in radiotherapy for locally advanced head and neck cancer patients
Authors: Franzese Ciro , Fogliata Antonella , Franceschini Davide , Navarria Pierina , Cozzi Luca , Tomatis Stefano , De Virgilio Armando , Spriano Giuseppe , Scorsetti Marta 
Published: May 2019

ObjectiveTo analyze two cohorts of locally advanced head and neck cancer (LAHNC) patients treated with two schedules of hypofractionated radiotherapy and 5 versus 3 mm clinical target volume–planning target volume (CTV‐PTV) margins.Methods145 patients were included. The patient cohort was divided into two groups. Group A included 97 patients treated with 69.96/54.45 grays (Gy) to the high‐risk and low‐risk volumes, respectively, in 33 fractions, with 5 mm margins. Group B included 48 patients treated with 66/54 Gy in 30 fractions using 3 mm margins. Toxicity was recorded according to the Common Toxicity Criteria version 3. Patient outcomes for locoregional control (LRC), disease‐free survival (DFS), and overall survival (OS) were determined.ResultsMedian follow‐up was 26 months. In terms of toxicity, acute dysphagia worsened significantly (P = 0.003) in group B, whereas acute salivary toxicity tended to significance (P = 0.071). No significant late toxicity differences were recorded. Rates of LRC at 1 and 2 years were 90.1% ± 2.6% and 84.2% ± 3.4%, respectively, with superiority for group A (P = 0.045). The statistical significance remained for the low‐dose level (P = 0.007) but not for high dose (P = 0.110). Rates of DFS at 1 and 2 years were 84.9% ± 3.1% and 76.5% ± 3.9%, respectively, whereas rates of OS were 95.9% ± 1.8% and 91.6% ± 2.7%, respectively. No differences were observed between the two groups in terms of DFS (P = 0.270) and OS (P = 0.152).ConclusionThe use of reduced CTV to PTV margins and dose reduction with hypofractionation schedule can improve the pattern of toxicity in LAHNC patients. This approach resulted in an increased rate of locoregional progression, particularly in low‐risk regions.Level of Evidence4Laryngoscope, 130:E163–E170, 2020
Aberrant innominate artery: A possible hazard during total laryngectomy
Authors: Nijkamp Jamie , Jaafar Rohaizam Bin Japar , Postma Linda , Snoeijs Maarten , Qiu Shao Shan Shan , Tan Bing 
Published: May 2019

BackgroundSurgical management in laryngeal carcinoma remains a challenge with countless unexpected complications. Great vessel anomalies such as anomaly of the innominate artery carry high risk of morbidity and mortality if not managed properly.MethodsWe present our first experience with an aberrant innominate artery during total laryngectomy which complicated the whole surgical procedure and tracheostoma placement.ResultsWe decided to place a pectoralis major muscle flap to separate and cover up the aberrant vessel from the trachea and end‐stoma which ultimately did not lead to major complications postoperatively and postradiation therapy.ConclusionAberrant innominate artery is an extremely rare entity and failure of recognizance can lead to hazardous complications. Preoperative angiography needs to be done if there are high suspicions of aberrant vessels in the operative field. Careful dissection of the head and neck region, and prompt decision making are mandatory to manage such cases.Levels of EvidenceCase Report
Chronic inflammatory response in the rat lung to commonly used contrast agents for videofluoroscopy
Authors: Ueha Rumi , Nativ‐Zeltzer Nogah , Sato Taku , Goto Takao , Nito Takaharu , Tsunoda Koichi , Belafsky Peter C. , Yamasoba Tatsuya 
Published: May 2019

ObjectivesContrast agents (CAs) are essential for upper gastrointestinal and videofluoroscopic swallow studies (VFSSs). Recently, we reported that small amounts of Ba aspiration caused severe acute lung inflammation in a rodent model. However, the underlying molecular biological mechanisms of chronic response to CA aspiration remain unclear. The aims of this study were to explore the underlying molecular biological mechanisms of the chronic response to three kinds of CA aspiration on the lung.Study DesignAnimal model.MethodsEight‐week‐old male Sprague Dawley rats were divided into five groups (n = 6, each group). Three groups underwent tracheal instillation of one of three CAs: barium sulfate (Ba), ionic iodinated contrast agent (ICA), and nonionic iodinated contrast agent (NICA). A sham group was instilled with air and a control group was instilled with saline. All animals were euthanized 30 days after treatment and histological and gene analyses were performed.ResultsNo animal died after CA or sham/control aspiration. Ba particles remained after 30 days and caused histopathologic changes and inflammatory cell infiltration. Iodinated ICA and NICA did not result in perceptible histologic change. Expression of Tnf, an inflammatory cytokine was increased in only Ba aspirated rats (P = .0076). Other inflammatory cytokines and fibrosis‐related genes did not alter between groups.ConclusionAspirated Ba particles did not clear from the lung within a month and caused mild chronic pulmonary inflammation. ICA and NICA did not cause any inflammatory responses in the lungs, suggesting that ICA and NICA may be safer CAs for VFSS than Ba.Level of EvidenceNA
A narrative review of the epidemiology, diagnosis, and treatment of latent stress urinary incontinence
Authors: Edenfield Autumn , Patnam Radhika , Swift Steven 
Published: May 2019

AimsTo review the current literature on the development of latent stress urinary incontinence (SUI) or SUI that occurs following pelvic organ prolapse therapy in patients who were continent prior to therapy. To make recommendations on how to best evaluate and manage patients with pelvic organ prolapse who are continent.MethodsThis is a narrative review using Google scholar and cross referencing identified manuscripts. We used the British Medical Journals grading of literature to assign letter grades to level of statements and recommendations.ResultsThe literature suggest about 40% of women with advanced pelvic organ prolapse who are continent will develop SUI after surgery to correct their pelvic organ prolapse. Reduction cough stress testing can help identify those patients at risk to develop SUI with a PPV of 60%. Reduction cough stress testing is best done using large rectal swabs or scopettes. The literature on how to best manage patients with advanced pelvic organ prolapse and are continent to avoid latent SUI is mixed and the best recommendations are based on sound literature that is incomplete.ConclusionsUnderstanding that latent SUI is a potential complication in any subject with advanced pelvic organ prolapse is necessary to pre‐operative counseling. Deciding on the best management strategy is not clear cut and therefore should involve patient input in the decision making process.
Extension of a simplified Baldwin–Lomax model to nonequilibrium turbulence: Model, analysis and algorithms
Authors: Rong Yao , Layton William , Zhao Haiyun 
Published: May 2019

AbstractComplex turbulence not at statistical equilibrium is impossible to simulate using eddy viscosity models due to a backscatter. This research presents the way to correct the Baldwin–Lomax model for nonequilibrium effects and gives an analysis of the energy evolution in the corrected model. Furthermore, a finite element approximation of the corrected eddy model with first‐order and second‐order time discretization is also presented. A numerical test is given to support the theory.