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Di Shu, Ionel Simbotin, Robin Côté
We investigate the energy dependence of inelastic processes in systemswhich possess Efimov states. We consider the three-body recombinationrate $K_3$ where three free atoms interact to produce anatom--dimer pair, and the relaxation rate $K_{\rm rel}$where an atom quenches a weakly bound state of a dimernear an Efimov resonance to more deeply bound levels.Using a modelcapturing the key features of the Efimov problem, weidentify new energy regimes for $K_3$, namely the NTR (NearThreshold Resonance) regime behavior $E^{-2}$ for negativescattering lengths and the NTS (Near Threshold Suppression) regimebehavior $E^2$ for positive scattering lengths...
October 19, 2016: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Luisa F Castiblanco, George W Sundin
Bacterial biofilms are multicellular aggregates encased in an extracellular matrix mainly composed of exopolysaccharides (EPSs), protein, and nucleic acids, which determines the architecture of the biofilm. Erwinia amylovora Ea1189 forms a biofilm inside the xylem of its host, that results in vessel plugging and water transport impairment. Production of the EPSs amylovoran and levan are critical for the formation of a mature biofilm. Additionally, cyclic dimeric GMP (c-di-GMP) was reported to positively regulate amylovoran biosynthesis and biofilm formation in E...
October 18, 2016: Molecular Plant Pathology
Jun Chen, Jeremy E Wulff
The Diels-Alder dimerization of cyclopentadiene carboxylic acid (or ester) affords only three products out of a total of 36 possible regioisomers. In this Communication, we compare two competing conceptual models for their ability to rationalize the selective formation of these three compounds. We find that calculated ΔHf values and orbital energy levels are sufficient to describe gross reactivity for the system, but that orbital coefficient arguments (and frontier molecular orbital theory in general) do not reliably predict the regioisomeric outcome for the reaction...
October 18, 2016: Organic & Biomolecular Chemistry
Daniel Corrigan, Christiana Prucnal, Christopher Kabrhel
The diagnosis or exclusion of pulmonary embolism (PE) remains challenging for emergency physicians. Symptoms can be vague or non-existent, and the clinical presentation shares features with many other common diagnoses. Diagnostic testing is complicated, as biomarkers, like the D-dimer, are frequently false positive, and imaging, like computed tomography pulmonary angiography, carries risks of radiation and contrast dye exposure. It is therefore incumbent on emergency physicians to be both vigilant and thoughtful about this diagnosis...
September 2016: Clin Exp Emerg Med
Dirk Fahrenkamp, Jinyu Li, Sabrina Ernst, Hildegard Schmitz-Van de Leur, Nicolas Chatain, Andrea Küster, Steffen Koschmieder, Bernhard Lüscher, Giulia Rossetti, Gerhard Müller-Newen
STAT5 is an essential transcription factor in hematopoiesis, which is activated through tyrosine phosphorylation in response to cytokine stimulation. Constitutive activation of STAT5 is a hallmark of myeloid and lymphoblastic leukemia. Using homology modeling and molecular dynamics simulations, a model of the STAT5 phosphotyrosine-SH2 domain interface was generated providing first structural information on the activated STAT5 dimer including a sequence, for which no structural information is available for any of the STAT proteins...
October 18, 2016: Scientific Reports
David G Reuter, Yuk Law, Wayne C Levy, Stephen P Seslar, R Eugene Zierler, Mark Ferguson, James Chattra, Tim McQuinn, Lenna L Liu, Mark Terry, Patricia S Coffey, Jane A Dimer, Coral Hanevold, Joseph T Flynn, F Bruder Stapleton
The morbidity and mortality associated with preeclampsia is staggering. The physiology of the Page kidney, a condition in which increased intrarenal pressure causes hypertension, appears to provide a unifying framework to explain the complex pathophysiology. Page kidney hypertension is renin-mediated acutely and ischemia-mediated chronically. Renal venous outflow obstruction also causes a Page kidney phenomenon, providing a hypothesis for the increased vulnerability of a subset of women who have what we are hypothesizing is a "renal compartment syndrome" due to inadequate ipsilateral collateral renal venous circulation consistent with well-known variation in normal venous anatomy...
September 15, 2016: Journal of the American Society of Hypertension: JASH
Smita Gupta, Sunita Yadav, Venkatesan Suryanarayanan, Sanjeev K Singh, Jitendra K Saxena
Guanylate kinase is one of the key enzymes in nucleotide biosynthesis. The study highlights the structural and functional properties of Brugia malayi Guanylate kinase (BmGK) in the presence of chemical denaturants. An inactive, partially unfolded, dimeric intermediate was observed at 1-2M urea while GdnCl unfolding showed monomer molten globule like intermediate at 0.8-1.0M. The results also illustrate the protective role of substrates in maintaining the integrity of the enzyme. The thermo stability of protein was found to be significantly enhanced in the presence of the substrates...
October 14, 2016: International Journal of Biological Macromolecules
Jie Li, Yanli Zhang, Xianhui Cai, Qingqing Xia, Jingmeng Chen, Yi Liao, Zuguo Liu, Yalin Wu
Effective clearance of all-trans-retinal (atRAL) from retinal pigment epithelial (RPE) cells is important for avoiding its cytotoxicity. However, the metabolism of atRAL in RPE cells is poorly clarified. The present study was designed to analyze metabolic products of atRAL and to compare the cytotoxicity of atRAL versus its derivative all-trans-retinal dimer (atRAL-dimer) in human RPE cells. We found that all-trans-retinol (atROL) and a mixture of atRAL condensation metabolites including atRAL-dimer and A2E were generated after incubating RPE cells with atRAL for 6h, and the amount of atRAL-dimer was significantly higher than that of A2E...
October 14, 2016: Toxicology
Jun Lu, Xing Wang, Qiuhua Chen, Mingqi Chen, Lu Cheng, Hua Jiang, Zhiguang Sun
BACKGROUND AND AIMS: Continuous renal replacement therapy (CRRT) is an important treatment in the intensive care unit (ICU). Nevertheless, the outcome of CRRT remains unclear. It is important to find a useful and easy indicator to predict the prognosis in patients on CRRT treatment. We undertook this study to observe the association between serum D-dimer level and mortality of ICU patients in the treatment of CRRT. METHODS: A total of 149 patients who received CRRT were enrolled in our study...
July 2016: Archives of Medical Research
Tiernan Thomas O'Malley, William M Wittbold, Sara Linse, Dominic M Walsh
Extracts of Alzheimer's disease (AD) brain that contain what appear to be SDS-stable amyloid β-protein (Aβ) dimers potently block LTP and impair memory consolidation. Brain-derived dimers can be physically separated from Aβ monomer, consist primarily of Aβ42 and resist denaturation by powerful chaotropic agents. In nature, covalently cross-linked Aβ dimers could be generated in only one of two different ways - either by the formation of a dityrosine (DiY) or an isopeptide ε-(γ-glutamyl)-lysine (Q-K) bond...
October 17, 2016: Biochemistry
Wen Song, Zhifu Han, Jizong Wang, Guangzhong Lin, Jijie Chai
The large family of membrane-localized receptor kinases (RKs) has important roles in many aspects of plant physiology. RKs function to perceive external signals, leading to RK activation and downstream signaling. Progress has been recently made in structural elucidation of the mechanisms underlying ligand recognition and activation of RKs. These structural studies mainly on leucine-rich repeat RKs (LRR-RKs) support the idea that ligand-induced dimerization is an essential step for RK activation, though the modes for dimerization vary...
October 14, 2016: Current Opinion in Structural Biology
Marko Melander, Elvar Örn Jónsson, Jens Jørgen Mortensen, Tejs Vegge, Juan María García Lastra
Combining constrained density function theory (cDFT) with Marcus theory is an efficient and promising way to address charge transfer reactions. Here, we present a general and robust implementation of cDFT within the projector augmented wave (PAW) framework. PAW pseudopotentials offer a reliable frozen-core electron description across the whole periodic table, with good transferability, as well as facilitate the extraction of all-electron quantities. The present implementation is applicable to two different wave function representations -- atomic centred basis sets (LCAO) and the finite-difference (FD) approximation utilizing real-space grids...
October 17, 2016: Journal of Chemical Theory and Computation
Cornelia Klose, Filippo Venezia, Andrea Hussong, Stefan Kircher, Eberhard Schäfer, Christian Fleck
No abstract text is available yet for this article.
October 17, 2016: Nature Plants
Shi-Jun Yue, Cheng Qu, Peng-Xuan Zhang, Yu-Ping Tang, Yi Jin, Jian-Shuang Jiang, Ya-Nan Yang, Pei-Cheng Zhang, Jin-Ao Duan
Two novel quinochalcone C-glycosides, carthorquinosides A (1) and B (2), were isolated from the florets of Carthamus tinctorius. Their structures, including the absolute configurations, were established by analysis of NMR and MS data, together with chemical degradation and electronic circular dichroism spectra. Compound 1 has an unprecedented quinochalcone-flavonol structure linked via a methylene bridge, and compound 2 comprises two glucopyranosylquinochalcone moieties linked via the formyl carbon of an acyclic glucosyl unit...
October 17, 2016: Journal of Natural Products
M Damoder Reddy, Frank R Fronczek, E Blake Watkins
Rh-catalyzed, chelation-induced, C-5 regioselective C-H functionalization of 8-amidoquinolines with a range of N-Boc aminals is reported for the first time. The addition of in situ generated imines to C(sp(2))-H bonds afforded branched amines in good to excellent yields. Moreover, this transformation features good functional group compatibility, broad substrate scope, and mild reaction conditions and is suitable for gram-scale synthesis. In addition, an unprecedented, chelation-induced, site-selective, remote dimerization of quinolines led to the formation of dimer frameworks in moderate yields under Rh-catalyzed conditions...
October 17, 2016: Organic Letters
Jun-Qin Qiao, Chao Liang, Lan-Chun Wei, Zhao-Ming Cao, Hong-Zhen Lian
The study on nucleic acid retention in ion-pair reversed-phase high-performance liquid chromatography mainly focuses on size-dependence, however, other factors influencing retention behaviors have not been comprehensively clarified up to date. In this present work, the retention behaviors of oligonucleotides and double-stranded DNAs were investigated on silica-based C18 stationary phase by ion-pair reversed-phase high-performance liquid chromatography. It is found that the retention of oligonucleotides was influenced by base composition and base sequence as well as size, and oligonucleotides prone to self-dimerization have weaker retention than those not prone to self-dimerization but with the same base composition...
October 17, 2016: Journal of Separation Science
Steven Silverman, John Moses, K Barry Sharpless
Vancomycin has long been considered a drug of last resort. Its efficiency in treating multiple drug-resistant bacterial infections, particularly methicillin resistant S. aureus (MRSA), has had a profound effect on the treatment of life-threatening infections. However, the emergence of resistance to vancomycin is a cause for significant world-wide concern, prompting the urgent development of new effective treatments for antibiotic resistant bacterial infections. Harnessing the benefits of multivalency and cooperativity against vancomycin-resistant strains, we report a Click Chemistry approach towards reengineered vancomycin derivatives and the synthesis of a number of dimers with increased potency against MRSA and vancomycin resistant Enterococci (VRE)...
October 16, 2016: Chemistry: a European Journal
Seungwoo Hong, Soo Jeong Jang, Kyung-Bin Cho, Wonwoo Nam
Oxygen atom transfer (OAT) reaction between an Fe(V)O complex and a Mn(III) complex resulted in the eventual formation of their corresponding Fe(III) and Mn(V)O complexes. The reaction proceeded via an initial fast OAT reaction between the Fe(V)O and Mn(III) complexes, yielding a half equivalent of a Mn(V)O complex and a μ-oxo bridged Fe(IV) dimer. The dimer regenerated the Fe(V)O species via equilibrium, which then reacted with the remaining Mn(III) complex to produce another half equivalent of the Mn(V)O complex...
October 17, 2016: Chemical Communications: Chem Comm
A Sowmya, G N Anil Kumar, Sujeet Kumar, Subhas S Karki
In the title imidazo[2,1-b][1,3,4]thia-diazole derivative, C19H14ClN3OS, the 4-methyl-benzyl and chloro-phenyl rings are inclined to the planar imidazo[2,1-b][1,3,4]thia-diazole moiety (r.m.s. deviation = 0.012 Å) by 64.5 (1) and 3.7 (1)°, respectively. The mol-ecular structure is primarily stabilized by a strong intra-molecular C-H⋯O hydrogen bond, leading to the formation of a pseudo-seven-membered S(7) ring motif, and a short intra-molecular C-H⋯N contact forming an S(5) ring motif. In the crystal, mol-ecules are linked by pairs of C-H⋯S hydrogen bonds, forming inversion dimers...
October 1, 2016: Acta Crystallographica. Section E, Crystallographic Communications
A Dominic Fortes, Christopher M Howard, Ian G Wood, Matthias J Gutmann
Single crystals of glycine zinc sulfate penta-hydrate [systematic name: hexa-aqua-zinc tetra-aquadiglycinezinc bis-(sulfate)], [Zn(H2O)6][Zn(C2H5NO2)2(H2O)4](SO4)2, have been grown by isothermal evaporation from aqueous solution at room temperature and characterized by single-crystal neutron diffraction. The unit cell contains two unique ZnO6 octa-hedra on sites of symmetry -1 and two SO4 tetra-hedra with site symmetry 1; the octa-hedra comprise one [tetra-aqua-diglycine zinc](2+) ion (centred on one Zn atom) and one [hexa-aqua-zinc](2+) ion (centred on the other Zn atom); the glycine zwitterion, NH3(+)CH2COO(-), adopts a monodentate coordination to the first Zn atom...
October 1, 2016: Acta Crystallographica. Section E, Crystallographic Communications
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