bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanisms of HNO Reactions with Ferric Heme Proteins
Authors: Shi Yelu , Zhang Yong 
Published: October 2018

AbstractMany HNO‐scavenging pathways exist to regulate its biological and pharmacological activities. Such reactions often involve ferric heme proteins and form an important basis for HNO probe development. However, mechanisms of HNO reactions with ferric heme proteins are largely unknown. We performed a computational investigation using metmyoglobin and catalase as representative ferric heme proteins with neutral and negatively charged axial ligands to provide the first detailed pathways. The results reproduced experimental barriers well with an average error of 0.11 kcal mol−1. The rate‐limiting step was found to be dissociation of the resting ligand or HNO coordination when there is no resting ligand. For both heme proteins, in contrast to the non‐heme case, the reductive nitrosylation step was found to be barrierless proton‐coupled electron transfer, which provides the major thermodynamic driving force for the overall reaction. The origin of the difference in reactivity between metmyoglobin and catalase was also revealed.
Catalytic Radical Process for Enantioselective Amination of C(sp3)−H Bonds
Authors: Li Chaoqun , Lang Kai , Lu Hongjian , Hu Yang , Cui Xin , Wojtas Lukasz , Zhang X. Peter 
Published: October 2018

AbstractA new catalytic radical system involving CoII‐based metalloradical catalysis is effective in activating sulfamoyl azides for enantioselective radical 1,6‐amination of C(sp3)−H bonds, affording six‐membered chiral heterocyclic sulfamides in high yields with excellent enantioselectivities. The CoII‐catalyzed C−H amination features an unusual degree of functional‐group tolerance and chemoselectivity. The unique reactivity and stereoselectivity is attributed to the underlying stepwise radical pathway. The resulting optically active cyclic sulfamides can be readily converted into synthetically useful chiral 1,3‐diamine derivatives without loss in enantiopurity.
Wavelength‐Controlled Dynamic Metathesis: A Light‐Driven Exchange Reaction between Disulfide and Diselenide Bonds
Authors: Fan Fuqiang , Ji Shaobo , Sun Chenxing , Liu Cheng , Yu Ying , Fu Yu , Xu Huaping 
Published: October 2018

AbstractWavelength‐controlled dynamic processes are mostly based on light‐triggered isomerization or the cleavage/formation of molecular connections. Control over dynamic metathesis reactions by different light wavelengths, which would be useful in controllable dynamic chemistry, has rarely been studied. Taking advantage of the different bond energies of disulfide and diselenide bonds, we have developed a wavelength‐driven exchange reaction between disulfides and diselenides, which underwent metathesis under UV light to produce Se−S bonds. When irradiated with visible light, the Se−S bonds were reversed back to those of the original reactants. The conversion of the exchange depends on the wavelength of the incident light. This light‐driven metathesis chemistry was also applied to tune the mechanical properties of polymer materials. The visible‐light‐induced reverse reaction was compatible with reductant‐catalyzed disulfide/diselenide metathesis, and could be utilized to develop a dissipative system with light as the energy input.
AISeC2H (AI=K, Rb, Cs): Crystalline Compounds with the Elusive −Se‐C≡C‐H Anion
Authors: Hetzert Marc , Werker Melanie , Ruschewitz Uwe 
Published: October 2018

AbstractBy reaction of alkali metal acetylides, AIC2H (AI=K, Rb, Cs), with elemental selenium in liquid ammonia highly crystalline powders of AISeC2H were obtained. The structure analysis based on the resulting synchrotron powder diffraction data revealed that all compounds crystallize in an orthorhombic unit cell (Cmc21, Z=4) exhibiting the elusive −SeC2H anion, which is unprecedented in a crystalline compound up to now. Elemental analysis and IR spectroscopic data confirm this finding. Upon heating, AISeC2H compounds release acetylene based on DSC/TGA experiments resulting in powders with the proposed composition AI2Se2(C2). The resulting powders were indexed with small cubic unit cells, but a reasonable structural model could not be developed up to now. Upon exposure of AISeC2H compounds to water elemental selenium is formed again.
Noncovalent Carbon‐Bonding Interactions in Proteins
Authors: Mundlapati V. Rao , Sahoo Dipak Kumar , Bhaumik Suman , Jena Subhrakant , Chandrakar Amol , Biswal Himansu S. 
Published: October 2018

AbstractCarbon bonds (C‐bonds) are the highly directional noncovalent interactions between carbonyl‐oxygen acceptors and sp3‐hybridized‐carbon σ‐hole donors through n→σ* electron delocalization. We have shown the ubiquitous existence of C‐bonds in proteins with the help of careful protein structure analysis and quantum calculations, and have precisely determined C‐bond energies. The importance of conventional noncovalent interactions such as hydrogen bond (H‐bonds) and halogen bond (X‐bonds) in the structure and function of biological molecules are well established, while carbon bonds C‐bonds have still to be recognized. We have shown that C‐bonds are present in proteins, contribute enthalpically to the overall hydrophobic interaction and play a significant role in the photodissociation mechanism of myoglobin and the binding of nucleobases to proteins.
Catalyst‐ and Template‐Free Ultrafast Visible‐Light‐Triggered Dimerization of Vinylpyridine‐Functionalized Tetraarylaminoborane: Intriguing Deep‐Blue Delayed Fluorescence
Authors: Neena Kalluvettukuzhy K. , Sudhakar Pagidi , Thilagar Pakkirisamy 
Published: October 2018

AbstractA photoredox‐catalyst‐ and template‐free sunlight‐induced molecular dimerization of a vinylpyridine‐functionalized tetraarylaminoborane (TAAB) has been accomplished for the first time. The reaction is quantitative, highly regioselective, and thermally irreversible. The presence of the propeller‐shaped TAAB framework allows selective photodimerization of one of the two vinyl pyridine units. Monomer 1 and photodimer 2 exhibit distinct photophysical properties with delayed fluorescence (DF) both in solution and the solid state, which was confirmed by steady‐state and time‐resolved luminescence studies. Quantum mechanical calculations were performed to support the experimental observations. Our new approach using [2+2] cycloaddition chemistry paves the way for the development of highly sought‐after deep‐blue DF materials.
Bioorthogonal Click Chemistry Enables Site‐specific Fluorescence Labeling of Functional NMDA Receptors for Super‐Resolution Imaging
Authors: Neubert Franziska , Beliu Gerti , Terpitz Ulrich , Werner Christian , Geis Christian , Sauer Markus , Doose Sören 
Published: October 2018

AbstractSuper‐resolution microscopy requires small fluorescent labels. We report the application of genetic code expansion in combination with bioorthogonal click chemistry to label the NR1 domain of the NMDA receptor. We generated NR1 mutants incorporating an unnatural amino acid at various positions in order to attach small organic fluorophores such as Cy5‐tetrazine site‐specifically to the extracellular domain of the receptor. Mutants were optimized with regard to protein expression, labeling efficiency and receptor functionality as tested by fluorescence microscopy and whole‐cell patch clamp. The results show that bioorthogonal click chemistry in combination with small organic dyes is superior to available immunocytochemistry protocols for receptor labeling in live and fixed cells and enables single‐molecule sensitive super‐resolution microscopy experiments.
Towards a Supertough Thermoplastic Polyisoprene Elastomer Based on a Biomimic Strategy
Authors: Tang Maozhu , Zhang Rong , Li Shiqi , Zeng Jian , Luo Mingchao , Xu Yun‐Xiang , Huang Guangsu 
Published: October 2018

AbstractNatural rubber is one of most famous self‐reinforced rubbers thanks to the phenomenon of strain‐induced crystallization. It is usually used in a vulcanized form to enhance the mechanical strength but this results in recycling issues. Herein a thermoplastic analogue of vulcanized natural rubber is obtained as a structural mimic. Terminally functionalized polyisoprene rubber B‐4A‐PIP was prepared by using tetra‐analine as physical crosslinking units. The strong binding of tetra‐analine groups gave B‐4A‐PIP a high tensile strength (15 MPa) and breaking strain of 890 %, which is much higher than those of undecorated copolymer B‐OH‐PIP. B‐4A‐PIP has a similar onset strain of crystallization and crystallization index to vulcanized natural rubber. Randomly functionalized polyisoprene R‐4A‐PIP showed a much lower mechanical strength and SIC properties although R‐4A‐PIP and B‐4A‐PIP possessed similar molecular weights and amounts of tetra‐analine groups.
Array‐based “Chemical Nose” Sensing in Diagnostics and Drug Discovery
Authors: Geng Yingying , Peveler William J. , Rotello Vincent M. 
Published: October 2018

AbstractArray‐based sensor “chemical nose/tongue” platforms are inspired by the mammalian olfactory system. Multiple sensor elements in these devices selectively interact with target analytes, producing a distinct pattern of response and enabling analyte identification. This approach offers unique opportunities relative to “traditional” highly specific sensor elements such as antibodies. Array‐based sensors excel at distinguishing small changes in complex mixtures, and this capability is being leveraged for chemical biology studies and clinical pathology, enabled by a diverse toolkit of new molecular, bioconjugate and nanomaterial technologies. Innovation in the design and analysis of arrays provides a robust set of tools for advancing biomedical goals, including precision medicine.
Storage‐Induced Changes in Volatile Compounds in Argan Oils Obtained from Raw and Roasted Kernels
Authors: Gracka Anna , Majcher Małgorzata , Kludská Eliška , Hradecký Jaromír , Hajšlová Jana , Jeleń Henryk H. 
Published: October 2018

AbstractVolatile compounds of argan oils obtained from raw and roasted kernels and subjected to accelerated storage test at 60 °C were profiled by means of headspace solid‐phase microextraction with gas chromatography coupled with high‐resolution time‐of‐flight mass spectrometry (HS‐SPME‐GC‐HRToFMS), followed by statistical multivariate analysis (MVA). Main volatile markers differentiating oils during storage were identified as 2‐methylbutanal, acetic acid, pentanal, hexanal, 2,5‐dimethylpyrazine, methyl pyrazine, 2,3‐butanediol, and 1‐methyl‐1H‐pyrrole. Principal component analysis (PCA) results show that MVA is suitable for differentiating between raw and roasted argan oils of various degrees of oxidation. Key odorants in both oils were determined by gas chromatography‐olfactometry (GC‐O) analysis, indicating butanal as the most prominent odorant for raw argan oil (flavor dilution [FD] = 8), whereas 3‐isopropyl‐2‐methoxypyrazine and 2‐ethyl‐3,5‐dimethylpyrazine with FD values of 1024 were the most prominent among 23 odorants in argan oil obtained from roasted kernels. Peroxide values (PV) indicate that argan oil obtained from roasted kernels is significantly less prone to oxidation than oil obtained from unroasted kernels.
Tales from the outer limits: Archaeological geophysical prospection in lowland peat environments in the British Isles
Authors: Armstrong Kayt , Cheetham Paul , Darvill Tim 
Published: October 2018

AbstractIn order to systematically investigate the potential of conventional near surface geophysical techniques to locate waterlogged archaeological targets in peatlands, the authors applied four conventional geophysical methods – earth resistance, ground‐penetrating radar (GPR), magnetic gradiometry and frequency domain electromagnetics (FDEM) – to four lowland peat archaeological test sites in Great Britain. In this article we demonstrate that a Neolithic trackway was identified in the GPR data in Somerset, with likely ‘proxy’ detections of chemical changes showing up in both electrical and magnetic surveys. This was determined by a coring programme and inductively coupled plasma optical emission spectrometry (ICP‐OES) multi‐element analysis of peat samples to determine the relative concentrations of geophysically relevant chemical elements. Though no Bronze Age timbers were detected at Flag Fen, a post‐Bronze Age agricultural landscape was identified in both the GPR and gradiometer surveys. We conclude that GPR has the greatest potential for archaeological geophysical prospection in peatland environments, but that electrical and magnetic methods can usefully be employed as secondary sources of information and should not be discounted from future research. Further, this article argues that better understandings must be developed of the impacts of geochemistry on geophysical data if we are going to realistically pursue ‘whole landscape’ surveys.
Autistic‐like traits in children are associated with enhanced performance in a qualitative visual working memory task
Authors: Hamilton Colin J. , Mammarella Irene C. , Giofrè David 
Published: October 2018

Prior research has suggested that individuals with Autism Spectrum Disorders (ASD) demonstrate heterogeneity in cognitive efficacy, challenged executive resources but efficient visual processing. These contrasts lead to opposing predictions about visuospatial working memory competency in both ASD and the broader autism phenotype (BAP); compromised by constrained executive processes, but potentially scaffolded by effective visual representation. It is surprising therefore, that there is a paucity of visual working memory (VWM) research in both the ASD and BAP populations, which have focused upon the visual features of the to‐be‐remembered stimulus. We assessed whether individual differences in VWM were associated with autistic‐like traits (ALTs) in the BAP. About 76 children carried out the Visual Just Noticeable Difference task, designed to measure high fidelity feature representation within VWM. ALTs were measured with the Children's Empathy Quotient and Systemizing Quotient. Analyses revealed a significant positive relationship between Systemizing and VWM performance. This complements ASD studies in visual processing and highlights the need for further research on the working memory—long‐term memory interface in ASD and BAP populations. Autism Research 2018, 11: 1494–1499. © 2018 International Society for Autism Research, Wiley Periodicals, Inc.Lay SummaryThis study was interested in how well children with high levels of autistic‐like traits (ALTs) carry out a task which involved memorizing, for brief time, the precise size of colored shapes. The results suggested that children with high levels of ALTs performed the task relatively well. This finding is in contrast to many previous studies suggest that ALTs are associated with poor memory, and suggests that future research needs to look more finely at how individuals carry out these tasks.
Local FK506 dose‐dependent study using a novel three‐dimensional organotypic assay
Authors: Tajdaran Kasra , Chan Katelyn , Zhang Jennifer , Gordon Tessa , Borschel Gregory H. 
Published: October 2018

AbstractLocal administration of FK506, an FDA approved immunosuppressant with neuroregenerative properties, is a promising technique to achieve improved peripheral nerve regeneration while preventing the side effects associated with the systemic administration of this drug. Although considerable research has been devoted to the development of clinically suitable systems for local delivery of FK506 to the site of nerve injury and repair, the optimal dose of FK506 for enhancement of axon regeneration in the peripheral nerve has not yet been established. To this end, we devised a three‐dimensional (3D) organotypic assay capable of mimicking the peripheral nerve. This assay consisted of a neonatal rat dorsal root ganglion (DRG) extending its neurites into the native peripheral nerve scaffold provided by an acellular nerve allograft (ANA). A novel 3D compartmented cell culture system was adapted from the 3D organotypic assay to achieve local delivery of FK506 just to the growing neurites in vitro and establish the required local dose of FK506 for peripheral nerve regeneration. A bimodal dose response was observed by culturing the entire DRG–ANA construct with media containing different concentrations of FK506. Low drug concentration of 1 pg/ml and high drug concentration of 100 ng/ml lead to the longest neurite extension in vitro. Furthermore, regardless of the FK506 concentration, concentrating the drug to the growing neurites resulted in significant increase in both neurite extension and neurite density, an effect that was not observed with the FK506 delivery to both neurites and neural cell bodies within DRG. The findings in this study provide valuable insight into the optimal local dose of FK506 for peripheral nerve regeneration. Furthermore, for the first time, this study suggests the potential interaction of FK506 with axons at the level of the growth cone.
Serine integrase recombinational engineering (SIRE): A versatile toolbox for genome editing
Authors: Snoeck Nico , De Mol Maarten L. , Van Herpe Dries , Goormans Anke , Maryns Isabelle , Coussement Pieter , Peters Gert , Beauprez Joeri , De Maeseneire Sofie L. , Soetaert Wim 
Published: October 2018

AbstractChromosomal integration of biosynthetic pathways for the biotechnological production of high‐value chemicals is a necessity to develop industrial strains with a high long‐term stability and a low production variability. However, the introduction of multiple transcription units into the microbial genome remains a difficult task. Despite recent advances, current methodologies are either laborious or efficiencies highly fluctuate depending on the length and the type of the construct. Here we present serine integrase recombinational engineering (SIRE), a novel methodology which combines the ease of recombinase‐mediated cassette exchange (RMCE) with the selectivity of orthogonal att sites of the PhiC31 integrase. As a proof of concept, this toolbox is developed for Escherichia coli. Using SIRE we were able to introduce a 10.3 kb biosynthetic gene cluster on different locations throughout the genome with an efficiency of 100% for the integrating step and without the need for selection markers on the knock‐in cassette. Next to integrating large fragments, the option for multitargeting, for deleting operons, as well as for performing in vivo assemblies further expand and proof the versatility of the SIRE toolbox for E. coli. Finally, the serine integrase PhiC31 was also applied in the yeast Saccharomyces cerevisiae as a marker recovery tool, indicating the potential and portability of this toolbox.
Cladosporin Derivatives Obtained by Biotransformation Provide Guidance for the Focused Derivatization of this Antimalarial Lead Compound
Authors: Fredenhagen Andreas , Schroer Kirsten , Schröder Harald , Hoepfner Dominic , Ligibel Mathieu , Porchet Zemp Liliane , Radoch Caroline , Freund Ernst , Meishammer Aldo 
Published: October 2018

AbstractCladosporin, a natural product known for decades, has recently been discovered to display potent and selective antiplasmodial activity by inhibition of lysyl‐tRNA synthetase. It was subjected to a panel of oxidative biotransformations with one fungal and two actinomycetes strains, as well as a triple mutant bacterial CYP102A1, yielding eight, mostly hydroxylated, derivatives. These new compounds covered a wide chemical space and contained two pairs of epimers in the tetrahydropyran ring. Although less potent than the parent compound, all analogues showed activity in a cell‐based synthetase assay, thus demonstrating uptake and on‐target activity in living cells with varying degrees of selectivity for the enzyme lysyl‐tRNA synthetase from Plasmodium falciparum and highlighting sites suitable for synthesis of future cladosporin analogues. Compounds with adjacent hydroxy functions showed different MS/MS fragmentation that can be explained in terms of an, in some cases, regioselective loss of water followed by a retro‐Diels–Alder reaction.
A prospective, single‐center, randomized study to assess whether automated coregistration of optical coherence tomography with angiography can reduce geographic miss
Authors: Koyama Kohei , Fujino Akiko , Maehara Akiko , Yamamoto Myong Hwa , Alexandru Dragos , Jennings Joan , Krug Patricia , Santiago Lyn M. , Murray Meghan , Bongiovanni Linda , Lee Tetsumin , Kim Song‐Yi , Wang Xiao , Lin Yongqing , Matsumura Mitsuaki , Ali Ziad A. , Sosa Fernando , Haag Elizabeth , Mintz Gary S. , Shlofmitz Richard A. 
Published: October 2018

AbstractObjectiveWe sought to evaluate whether automated coregistration of optical coherence tomography (OCT) with angiography reduces geographic miss (GM) during coronary stenting.BackgroundPrevious intravascular ultrasound or OCT studies have showed that residual disease at the stent edge or stent edge dissection was associated with stent thrombosis or edge restenosis. This has been termed GM.MethodsTwo hundred de novo coronary lesions were randomized in a 1:1 ratio to OCT‐guided percutaneous coronary intervention (PCI) with versus without automated coregistration of OCT with angiography. GM, the primary endpoint, was defined as angiographic ≥type B dissection or diameter stenosis >50% or OCT minimum lumen area <4.0 mm2 with significant residual disease or dissection (dissection flap >60°) within 5 mm from the stent edge.ResultsThe prevalence of GM was not different comparing OCT‐guided PCI with versus without automated coregistration (27.6% vs 34.0%, P = 0.33). However, there was a trend toward a reduced prevalence of significant distal stent edge dissection in lesions with automated coregistration (11.1% vs 20.8%, P = 0.07). The discrepancy in the distance between planned versus actual implanted stent location with automated coregistration was significantly shorter than without coregistration (1.9 ± 1.6 mm vs 2.6 ± 2.7 mm, P = 0.03), especially the prevalence of ≥5 mm discrepancy that was less frequent with automated coregistration.ConclusionsAutomated coregistration of OCT with angiography did not reduce the primary endpoint of GM after stent implantation.
Contrast modulation in chronic total occlusion percutaneous coronary intervention
Authors: Azzalini Lorenzo , Uretsky Barry , Brilakis Emmanouil S. , Colombo Antonio , Carlino Mauro 
Published: October 2018

AbstractThe intraplaque injection of contrast media in the recanalization of coronary chronic total occlusions (CTO) has witnessed a dynamic journey since its initial formulation. Contrast‐guided subintimal tracking and re‐entry (STAR) was the first contrast modulation technique for CTO percutaneous coronary intervention (PCI). With this technique, a forceful injection of a large volume of contrast (3–4 mL) was performed in order to achieve hydraulic recanalization of the vessel. This approach was associated with extensive vessel injury and unpredictable true lumen re‐entry, which were in turn linked to high rates of restenosis on follow‐up. In the subsequent iteration, called the “microchannel technique”, a smaller amount of contrast media (1 mL) was gently injected inside the plaque to modify its compliance by softening and recruiting loose tissue, which facilitated subsequent true‐to‐true lumen crossing with a polymer‐jacketed wire along paths of least resistance. The microchannel technique has later evolved into what is currently known as the “Carlino technique”, where a minimal volume of contrast media (<0.5 mL) is gently injected inside the occlusion, with the goal of modifying plaque compliance to facilitate guidewire and microcatheter advancement through a fibrocalcific plaque. The Carlino technique is now widely utilized to allow negotiation of difficult‐to‐cross occlusions, particularly by the “hybrid operators”, with high success rates and low incidence of complications. The purpose of this article is to provide a historical perspective on the use of contrast modulation in CTO PCI, its pathophysiological basis, as well as technical recommendations on how and when to perform these maneuvers.