bluuebunny/crossref_metadata_2025_split huggingface dataset:
Visualization of O‐GlcNAc Glycosylation Stoichiometry and Dynamics Using Resolvable Poly(ethylene glycol) Mass Tags
Authors: Clark Peter M. , Rexach Jessica E. , Hsieh‐Wilson Linda C. 
Published: December 2013

Abstract
O‐linked N‐acetylglucosamine (O‐GlcNAc) glycosylation is a dynamic protein posttranslational modification with roles in processes such as transcription, cell cycle regulation, and metabolism. Detailed mechanistic studies of O‐GlcNAc have been hindered by a lack of methods for measuring O‐GlcNAc stoichiometries and the interplay of glycosylation with other posttranslational modifications. We recently developed a method for labeling O‐GlcNAc‐modified proteins with resolvable poly(ethylene glycol) mass tags. This mass‐tagging approach enables the direct measurement of glycosylation stoichiometries and the visualization of distinct O‐GlcNAc‐modified subpopulations. Here, we describe procedures for labeling O‐GlcNAc glycoproteins in cell lysates with mass tags. Curr. Protoc. Chem. Biol. 5:281‐302 © 2013 by John Wiley & Sons, Inc.
Large Solvation Effect in the Optical Rotatory Dispersion of Norbornenone
Authors: Lahiri Priyanka , Wiberg Kenneth B. , Vaccaro Patrick H. , Caricato Marco , Crawford T. Daniel 
Published: December 2013

AbstractThe anomalously large chiroptical response of (1R,4R)‐norbornenone has been probed under complementary vapor‐phase and solution‐phase conditions to assess the putative roles of environmental perturbations. Measurements of the specific rotation for isolated (gas‐phase) molecules could not be reproduced quantitatively by comprehensive quantum‐chemical calculations based on density‐functional or coupled‐cluster levels of linear‐response theory, which suggests that higher‐order treatments may be needed to accurately predict such intrinsic behavior. A substantial, yet unexpected, dependence of the dispersive optical activity on the nature (phase) of the surrounding medium has been uncovered, with the venerable Lorentz local‐field correction reproducing solvent‐mediated trends in rotatory dispersion surprisingly well, whereas more modern polarizable continuum models for implicit solvation performed less satisfactorily.
The RING Domain of the Scaffold Protein Ste5 Adopts a Molten Globular Character with High Thermal and Chemical Stability
Authors: Walczak Michal J. , Samatanga Brighton , van Drogen Frank , Peter Matthias , Jelesarov Ilian , Wider Gerhard 
Published: December 2013

AbstractSte5 is a scaffold protein that controls the pheromone response of the MAP‐kinase cascade in yeast cells. Upon pheromone stimulation, Ste5 (through its RING‐H2 domain) interacts with the β and γ subunits of an activated heterodimeric G protein and promotes activation of the MAP‐kinase cascade. With structural and biophysical studies, we show that the Ste5 RING‐H2 domain exists as a molten globule under native buffer conditions, in yeast extracts, and even in denaturing conditions containing urea (7 M). Furthermore, it exhibits high thermal stability in native conditions. Binding of the Ste5 RING‐H2 domain to the physiological Gβ/γ (Ste4/Ste18) ligand is accompanied by a conformational transition into a better folded, more globular structure. This study reveals novel insights into the folding mechanism and recruitment of binding partners by the Ste5 RING‐H2 domain. We speculate that many RING domains may share a similar mechanism of substrate recognition and molten‐globule‐like character.
Stereocontrolled Syntheses of Tetralone‐ and Naphthyl‐Type Lignans by a One‐Pot Oxidative [3,3] Rearrangement/Friedel–Crafts Arylation
Authors: Reddel Jordan C. T. , Lutz Kelly E. , Diagne Abdallah B. , Thomson Regan J. 
Published: December 2013

AbstractThe development of a stereoselective one‐pot oxidative [3,3] sigmatropic rearrangement/Friedel–Crafts arylation that provides enantioenriched benzhydryl compounds is reported. The utility of this new transformation is demonstrated by the concise synthesis of several tetralone‐ and naphthyl‐type lignan natural products, many of which display anti‐malarial activity.
Solution Structure of a G‐quadruplex Bound to the Bisquinolinium Compound Phen‐DC3
Authors: Chung Wan Jun , Heddi Brahim , Hamon Florian , Teulade‐Fichou Marie‐Paule , Phan Anh Tuân 
Published: December 2013

AbstractPhen‐DC3 is a highly promising compound that specifically targets G‐quadruplexes, with potent biological effects observed in vivo. We used NMR spectroscopy to solve the structure of the complex formed between Phen‐DC3 and an intramolecular G‐quadruplex derived from the c‐myc promoter. Structural information revealed that Phen‐DC3 interacts with the quadruplex through extensive π‐stacking with guanine bases of the top G‐tetrad. On the basis of our structure, modifications are proposed for the development of this compound for selective targeting of a specific G‐quadruplex conformation.
EF24 prevents rotenone‐induced estrogenic status alteration in breast cancer
Authors: Roy Debarshi , Kabiraj Parijat , Pal Rituraj 
Published: December 2013

AbstractProtein disulfide isomerase (PDI), an important endoplasmic reticulum‐resident oxidoreductase chaperone can bind to estrogens as well as intact with its receptor proteins [i.e. estrogen receptors (ER) α and β]. It has been postulated that PDI also acts as an intracellular 17β‐estradiol (E2)‐binding protein that transports and accumulates E2 in live cells. Drop in E2 level promotes dissociation of E2 from PDI and released in cytosol; the released E2 can augment estrogen receptor‐mediated transcriptional activity and mitogenic action in cultured cells by modulating the ERβ/ERα ratio. In this study, we observed rotenone‐induced damage to PDI leads to significant increase in ERβ/ERα ratio by down‐regulating ERα and up‐regulating ERβ. We demonstrated that nitrosative stress induced disruption of the cellular estrogenic status can be prevented through diphenyl difluoroketone (EF24, curcumin analog) intervention by protecting PDI from reactive oxygen species (ROS)‐induced damage. Together, our study suggests that both PDI and EF24 can play a vital role in maintaining cellular estrogenic homeostasis.
Highly N2‐Selective Coupling of 1,2,3‐Triazoles with Indole and Pyrrole
Authors: Wen Jian , Zhu Li‐Li , Bi Qing‐Wei , Shen Zhu‐Qing , Li Xiao‐Xiao , Li Xin , Wang Zhen , Chen Zili 
Published: December 2013

AbstractHydrogen‐bond mediated coupling of 1,2,3‐triazoles to indoles and pyrroles results in N2 selective functionalization of the triazole moiety in moderate to excellent yields. The reaction was tolerant of un‐, mono‐ and disubstituted triazoles and was applied to synthesize tryptophan derived fluorescent amino acids.
Carbaborane‐Substituted 1,2,3‐Triphospholanes and 1‐Aza‐2,5‐diphospholane: New Synthetic Approaches
Authors: Kreienbrink Anika , Heinicke Sarah , Duong Pham Thi Thuy , Frank René , Lönnecke Peter , Hey‐Hawkins Evamarie 
Published: December 2013

AbstractNew phosphorus‐containing, five‐membered P,P,P and P,N,P heterocycles were synthesized and fully characterized. The P,P,P heterocycles, 1,2,3‐triphospholanes, can be synthesized by two different facile pathways, whereas the P,N,P compound, a 1‐aza‐2,5‐diphospholane, can only be obtained with silylamine.
Electrophilic Alkylations of Vinylsilanes: A Comparison of α‐ and β‐Silyl Effects
Authors: Laub Hans A. , Mayr Herbert 
Published: December 2013

AbstractKinetics of the reactions of benzhydrylium ions (Aryl2CH+) with the vinylsilanes H2CC(CH3)(SiR3), H2CC(Ph)(SiR3), and (E)‐PhCHCHSiMe3 have been measured photometrically in dichloromethane solution at 20 °C. All reactions follow second‐order kinetics, and the second‐order rate constants correlate linearly with the electrophilicity parameters E of the benzhydrylium ions, thus allowing us to include vinylsilanes in the benzhydrylium‐based nucleophilicity scale. The vinylsilane H2CC(CH3)(SiMe3), which is attacked by electrophiles at the CH2 group, reacts one order of magnitude faster than propene, indicating that α‐silyl‐stabilization of the intermediate carbenium ion is significantly weaker than α‐methyl stabilization because H2CC(CH3)2 is 103 times more reactive than propene. trans‐β‐(Trimethylsilyl)styrene, which is attacked by electrophiles at the silylated position, is even somewhat less reactive than styrene, showing that the hyperconjugative stabilization of the developing carbocation by the β‐silyl effect is not yet effective in the transition state. As a result, replacement of vinylic hydrogen atoms by SiMe3 groups affect the nucleophilic reactivities of the corresponding CC bonds only slightly, and vinylsilanes are significantly less nucleophilic than structurally related allylsilanes.
Allyl‐Functionalized Dioxynaphthalene[38]Crown‐10 Macrocycles: Synthesis, Self‐Assembly, and Thiol‐ene Functionalization
Authors: Choudhary Umesh , Northrop Brian H. 
Published: December 2013

AbstractFive dioxynaphthalene[38]‐crown‐10 (DNP38C10) macrocycles bearing one, two, three, or four allyl moieties have been synthesized and their ability to spontaneously self‐assemble with methyl viologen to form [2]pseudorotaxanes has been evaluated. Association constants between methyl viologen and several of the allyl‐functionalized DNP38C10 macrocycles are found to be comparable to that of methyl viologen and unfunctionalized DNP38C10, however, the enthalpic and entropic factors that underlie overall binding free energy vary systematically with increasing allyl substitution. These variations are explained through a combination of solution phase and solid‐state analysis of the macrocycles and their complexes. The utility of endowing DNP38C10 macrocycles with allyl moieties is further demonstrated by the ease with which they can be functionalized through thiol‐ene click chemistry.
Synthesis of Single‐enantiomer Bioactive Molecules: A Brief Overview
Authors: Rouf Abdul , Taneja S.C. 
Published: December 2013

ABSTRACTChiral‐center enantiomers have been shown to differ significantly in biological activity, pharmacodynamics, pharmacokinetics and toxicity. New developments in the stereoselective organic synthesis have enriched the vast literature of synthetic methodologies applicable to access natural products as well as bioactive molecules. These compounds also include new drugs, drug candidates and reagents used to explore biological processes. The article reviews the synthesis of optically pure drugs, biologically active intermediates and amino alcohols by using different methods. Chirality 26:63–78, 2014. © 2013 Wiley Periodicals, Inc.
An efficient interference mitigation approach via quasi‐access in two‐tier macro‐femto heterogeneous networks
Authors: Xiao Zhu , Li Zhongfeng , Zhang Xu , Liu Enjie , Yi Kechu 
Published: December 2013

SummaryTwo‐tier heterogeneous networks, where the current cellular networks, that is, macrocells, are overlapped with a large number of randomly distributed femtocells, can potentially bring significant benefits to spectral utilization and system capacity. In a two‐tier network, the cross‐tier interference needs to be handled properly. Unlike the downlink interference, the uplink (UL) interference at femtocell caused by macrocell user equipment (MUE) has not been addressed sufficiently. When an MUE is located near the coverage of femtocell, its transmit power may cause UL interference to the femtocell receiver, especially for the closed subscriber group femtocells that share the entire frequency spectrum with macrocell. We propose a novel quasi‐access strategy, which allows the interfering MUE to connect with the interfered femtocell access point (FAP) while only via UL. It can significantly alleviate the UL interference at the FAP as well as its neighbors, in the meantime, benefit the macro‐tier. Copyright © 2013 John Wiley & Sons, Ltd.
Diabetes, dysglycemia and cognitive dysfunction
Authors: Cukierman‐Yaffe Tali 
Published: December 2013

SummaryEvidence from the last decade supports the hypothesis that diabetes may be viewed as a disease of accelerated cognitive ageing. It is a risk factor for the development of dementia, for an accelerated rate of cognitive decline and for cognitive dysfunction. Thus, ‘diabetes‐related cognitive dysfunction’ may be viewed as another long‐term complication of diabetes. This article will review the evidence supporting this hypothesis and will elaborate on the implications for patient care, as well as discuss potential treatment options and their limitation. The final section reviews possible mechanistic explanations. Copyright © 2013 John Wiley & Sons, Ltd.
From Spherical Mesopores to Worm‐Shaped Mesopores: Morphology Transition in Titania–Polystyrene‐b‐poly(ethylene oxide) Composite Films with Increasing Sol–Gel Reaction Time
Authors: Cheng Ya‐Jun , Zhou Shaoying , Wolkenhauer Markus , Bumbu Gina‐Gabriela , Lenz Sebastian , Memesa Mine , Nett Sebastian , Emmerling Sebastian , Steffen Werner , Roth Stephan V. , Gutmann Jochen S. 
Published: December 2013

AbstractA morphology transition from spherical mesopores to worm‐shaped mesopores within titania block copolymer composite thin films has been observed by varying the sol–gel reaction time from 40 min to 48 h in the four‐component templating system of polystyrene‐b‐poly(ethylene oxide) (PS‐b‐PEO), 1,4‐dioxane, concentrated HCl, and titanium tetraisopropoxide (TTIP) with a PS‐b‐PEO mass concentration of 0.25 wt.‐%. The impact of the sol–gel reaction time on the local structure, long‐range lateral structure, and vertical structure of the as‐prepared, calcined, and UV‐degraded thin films as well as the structural changes in solution have been systematically investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM), grazing‐incidence small‐angle X‐ray scattering (GISAXS), X‐ray reflectivity (XRR), and dynamic light scattering (DLS). With sol–gel reaction times of up to 5 h, hexagonally organized spherical micelles are present within the as‐prepared composite films, in which the core of the spherical micelles is composed of the polystyrene (PS) block, and the corona is composed of the poly(ethylene oxide)–titania (PEO–titania) hybrid. Upon calcination or UV exposure, ordered mesoporous structures are formed owing to the removal of the PS block. With the sol–gel reaction time extended to 25 and 48 h, worm‐shaped micelles appear, and their quantity increases with increasing sol–gel reaction time. Worm‐shaped mesopores are formed by calcination or UV degradation. The GISAXS results prove that the local structural changes are representative over a macroscopic scale. The XRR results suggest that with the sol–gel reaction time extended to 48 h there is an additional thin layer beneath the mesoporous titania layer owing to the presence of a large amount of worm‐shaped micelles. The results of the DLS studies imply that the morphology transition from spherical micelles to worm‐shaped micelles is caused by a fusion process of the spherical micelles in solution.
Site‐Selectivity in the Protonation and Related Reactions of Chalcogenophosphinidene‐Bridged Dimolybdenum Cyclopentadienyl Complexes
Authors: Alvarez Belén , Alvarez M. Angeles , Amor Inmaculada , García M. Esther , García‐Vivó Daniel , Suárez Jaime , Ruiz Miguel A. 
Published: December 2013

AbstractReactions of the chalcogenophosphinidene‐bridged complexes syn‐[Mo2Cp2(μ‐κ2P,Z:κ1P,η4‐ZPMes*)(CO)2L] (L = CO, CNtBu; Z = O, S, Se), anti‐[Mo2Cp2(μ‐κ2P,S:κ1P,η4‐SPMes*)(CO)2L] (L = CO, CNtBu) and [Mo2Cp2{μ‐κ2P,Z:κ1P‐ZPH}(η6‐HMes*)(CO)2] (Z = S, Se, Te) towards sources of H+, Me+, and AuP(pTol)3+ cations were investigated (Mes* = 2,4,6‐C6H2tBu3; Cp = η5‐C5H5). The latter two electrophiles invariably added to the chalcogen atom to give corresponding derivatives [Mo2Cp2{μ‐κ2P,Z:κ1P,η4‐Mes*PZ(CH3)}(CO)3]BX4 [X = F, Z = O, S, Se; P–S 2.144(1) Å when Z = S and X = Ar′ = 3,5‐C6H3(CF3)2], [Mo2Cp2{μ‐κ2P,Z:κ1P,η4‐Mes*PZ(CH3)}(CNtBu)(CO)2]BF4 (Z = S, Se), and [AuMo2Cp2(μ3‐κ1S:κ2P,S:κ1P,η4‐SPMes*){P(pTol)3}(CO)3]PF6 [P–S 2.113(2), S–Au 2.320(2) Å]. Even when syn and anti isomers of the neutral precursor were used, the corresponding products were invariably characterized by their syn conformation (Z atom close to L ligand). Besides this, methylated derivatives of the chalcogenophosphinidene complexes bearing the formula [Mo2Cp2{μ‐κ2P,Z:κ1P‐HPZ(Me)}(η6‐HMes*)(CO)2](CF3SO3) (Z = S, Se, Te), were found in solution to exist as an equilibrium of corresponding cis and trans isomers differing, in each case, in the relative positioning of the Cp rings with respect to the MoPZ plane. In contrast to the above results, the protonation of all these compounds was quite sensitive to the particular chalcogenophosphinidene ligand and conformation of the complex. Protonation of the HPZ‐bridged complexes led to complex mixtures of products that could not be isolated or properly characterized. In contrast, the aryl‐bearing substrates reacted selectively to give corresponding complexes [Mo2Cp2{μ‐κ2P,Z:κ1P,η5‐ZP(C6H3tBu3)}(CO)3]BX4 (Z = S, X = F; P–S 2.032(2) Å when X = Ar′; Z = Se, X = F) and [Mo2Cp2{μ‐κ2P,Z:κ1P,η5‐ZP(C6H3tBu3)}(CNtBu)(CO)2]BAr′4 (Z = S, Se). The reaction of anti‐[Mo2Cp2(μ‐κ2P,S:κ1P,η4‐SPMes*)(CO)3] with HBF4·OEt2 at 213 K initially gave unstable intermediate anti‐[Mo2Cp2{μ‐κ2P,S:κ1P,η4‐Mes*PS(H)}(CO)3]BF4, which then rapidly converted at room temperature to the conventional isomer with the S atom close to the metallocene‐bound carbonyl ligand (syn isomer). This transformation is in agreement with Density Functional Theory calculations for neutral thiophosphinidene complexes; electrophilic attack at the sulfur atom, which is both an orbital‐ and charge‐favoured event, affords products that are more stable than those resulting from protonation at the metal sites. All these protonation reactions eventually result in an endo addition of H+ to the C6 atom of the Mes* ring with concomitant η4→η5 haptotropic shift of the resulting HMes* group. This conversion involves an easy H migration from S to the C6 atom, computed to take place with a low activation barrier of about 70 kJ/mol.
Prolyl‐isomerase Pin1 controls normal and cancer stem cells of the breast
Authors: Rustighi Alessandra , Zannini Alessandro , Tiberi Luca , Sommaggio Roberta , Piazza Silvano , Sorrentino Giovanni , Nuzzo Simona , Tuscano Antonella , Eterno Vincenzo , Benvenuti Federica , Santarpia Libero , Aifantis Iannis , Rosato Antonio , Bicciato Silvio , Zambelli Alberto , Del Sal Giannino 
Published: December 2013

AbstractMammary epithelial stem cells are fundamental to maintain tissue integrity. Cancer stem cells (CSCs) are implicated in both treatment resistance and disease relapse, and the molecular bases of their malignant properties are still poorly understood. Here we show that both normal stem cells and CSCs of the breast are controlled by the prolyl‐isomerase Pin1. Mechanistically, following interaction with Pin1, Notch1 and Notch4, key regulators of cell fate, escape from proteasomal degradation by their major ubiquitin‐ligase Fbxw7α. Functionally, we show that Fbxw7α acts as an essential negative regulator of breast CSCs' expansion by restraining Notch activity, but the establishment of a Notch/Pin1 active circuitry opposes this effect, thus promoting breast CSCs self‐renewal, tumor growth and metastasis in vivo. In human breast cancers, despite Fbxw7α expression, high levels of Pin1 sustain Notch signaling, which correlates with poor prognosis. Suppression of Pin1 holds promise in reverting aggressive phenotypes, through CSC exhaustion as well as recovered drug sensitivity carrying relevant implications for therapy of breast cancers.
Fabrication of uniform substrate based on silver nanoparticles decorated glycidyl methacrylate‐ethylene dimethacrylate porous material for ultrasensitive surface‐enhanced Raman scattering detection
Authors: Wang Xuan , Du Yiping , Li Qingqing , Wu Ting , Hu Huilian , Xu Ying , Zhang Han , Pan Yingcheng 
Published: December 2013

AbstractSurface‐enhanced Raman scattering (SERS) in practical application and theoretical research mostly depends on the performance of the SERS substrate. In this study, a new SERS substrate which is based on inverted self‐assembly of Ag nanoparticles (AgNPs) on glycidyl methacrylate‐ethylene dimethacrylate (GMA‐EDMA) porous material is developed. The characterization results show the GMA‐EDMA material with intertwined pores may contribute to the distribution of the AgNPs to fabricate an ideal substrate for SERS detection. In view of the characteristics of porous material, an inverted assembly method is proposed and used in operation to avoid the adverse gravity effect which may make the AgNPs plug up the pore channel and distribute on the surface unevenly. By the inverted self‐assembly method, the AgNPs could uniformly distribute on the surface of the material stably. The prepared substrate presents ultrasensitivity and good reproducibility for SERS detection. The enhancement factor of rhodamine 6G (R6G) detection is approximately 1014 and the relative standard deviation of each characteristic peak is about 15% when the substrate is used. The substrate also shows a good performance in detecting paraquat and thymine. The ultrasensitive SERS substrate can be readily integrated into pesticide detection systems and biological sample analysis. Copyright © 2013 John Wiley & Sons, Ltd.
Incorporating detection probability into northern Great Plains pronghorn population estimates
Authors: Jacques Christopher N. , Jenks Jonathan A. , Grovenburg Troy W. , Klaver Robert W. , Deperno Christopher S. 
Published: December 2013

ABSTRACTPronghorn (Antilocapra americana) abundances commonly are estimated using fixed‐wing surveys, but these estimates are likely to be negatively biased because of violations of key assumptions underpinning line‐transect methodology. Reducing bias and improving precision of abundance estimates through use of detection probability and mark‐resight models may allow for more responsive pronghorn management actions. Given their potential application in population estimation, we evaluated detection probability and mark‐resight models for use in estimating pronghorn population abundance. We used logistic regression to quantify probabilities that detecting pronghorn might be influenced by group size, animal activity, percent vegetation, cover type, and topography. We estimated pronghorn population size by study area and year using mixed logit‐normal mark‐resight (MLNM) models. Pronghorn detection probability increased with group size, animal activity, and percent vegetation; overall detection probability was 0.639 (95% CI = 0.612–0.667) with 396 of 620 pronghorn groups detected. Despite model selection uncertainty, the best detection probability models were 44% (range = 8–79%) and 180% (range = 139–217%) greater than traditional pronghorn population estimates. Similarly, the best MLNM models were 28% (range = 3–58%) and 147% (range = 124–180%) greater than traditional population estimates. Detection probability of pronghorn was not constant but depended on both intrinsic and extrinsic factors. When pronghorn detection probability is a function of animal group size, animal activity, landscape complexity, and percent vegetation, traditional aerial survey techniques will result in biased pronghorn abundance estimates. Standardizing survey conditions, increasing resighting occasions, or accounting for variation in individual heterogeneity in mark‐resight models will increase the accuracy and precision of pronghorn population estimates. © 2013 The Wildlife Society.