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https://www.readbyqxmd.com/read/28209526/robust-size-illusion-produced-by-expanding-and-contracting-flow-fields
#1
Xue Dong, Jianying Bai, Min Bao
A new illusion is described. Randomly positioned dots moved radially within an imaginary annular window. The dots' motion periodically changed the direction, leading to an alternating percept of expanding and contracting motion. Strikingly, the apparent size of the enclosed circular region shrank during the dots' expanding phases and dilated during the contracting phases. We quantitatively measured the illusion, and found that the presence of energy at the local kinetic edge could not account for the illusion...
February 13, 2017: Vision Research
https://www.readbyqxmd.com/read/28208498/coarsening-and-persistence-in-a-one-dimensional-system-of-orienting-arrowheads-domain-wall-kinetics-with-a-b%C3%A2-0
#2
Mahendra D Khandkar, Robin Stinchcombe, Mustansir Barma
We demonstrate the large-scale effects of the interplay between shape and hard-core interactions in a system with left- and right-pointing arrowheads <> on a line, with reorientation dynamics. This interplay leads to the formation of two types of domain walls, >< (A) and <> (B). The correlation length in the equilibrium state diverges exponentially with increasing arrowhead density, with an ordered state of like orientations arising in the limit. In this high-density limit, the A domain walls diffuse, while the B walls are static...
January 2017: Physical Review. E
https://www.readbyqxmd.com/read/28207200/a-pet-guided-framework-supports-a-multiple-arterial-input-functions-approach-in-dsc-mri-in-acute-stroke
#3
Michelle Livne, Vince I Madai, Peter Brunecker, Olivier Zaro-Weber, Walter Moeller-Hartmann, Wolf-Dieter Heiss, Kim Mouridsen, Jan Sobesky
BACKGROUND AND PURPOSE: In acute stroke, arterial-input-function (AIF) determination is essential for obtaining perfusion estimates with dynamic susceptibility-weighted contrast-enhanced magnetic resonance imaging (DSC-MRI). Standard DSC-MRI postprocessing applies single AIF selection, ie, global AIF. Physiological considerations, however, suggest that a multiple AIFs selection method would improve perfusion estimates to detect penumbral flow. In this study, we developed a framework based on comparable DSC-MRI and positron emission tomography (PET) images to compare the two AIF selection approaches and assess their performance in penumbral flow detection in acute stroke...
February 16, 2017: Journal of Neuroimaging: Official Journal of the American Society of Neuroimaging
https://www.readbyqxmd.com/read/28203230/the-major-immediate-early-protein-ie2-of-human-cytomegalovirus-is-sufficient-to-induce-proteasomal-degradation-of-cd83-on-mature-dendritic-cells
#4
Christiane S Heilingloh, Linda Grosche, Mirko Kummer, Petra Mühl-Zürbes, Lisa Kamm, Myriam Scherer, Melanie Latzko, Thomas Stamminger, Alexander Steinkasserer
Human cytomegalovirus (HCMV) is the prototypic beta-herpesvirus and widespread throughout the human population. While infection is asymptomatic in healthy individuals, it can lead to high morbidity and mortality in immunocompromised persons. Importantly, HCMV evolved multiple strategies to interfere with immune cell function in order to establish latency in infected individuals. As mature DCs (mDCs) are antigen-presenting cells able to activate naïve T cells they play a crucial role during induction of effective antiviral immune responses...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28202545/the-basis-for-acyl-specificity-in-the-tafazzin-reaction
#5
Michael Schlame, Yang Xu, Mindong Ren
Tafazzin is a mitochondrial enzyme that transfers fatty acids from phospholipids to lysophospholipids. Mutations in tafazzin cause abnormal molecular species of cardiolipin and the clinical phenotype of Barth syndrome. However, the mechanism by which tafazzin creates acyl specificity has been controversial. We have shown that the lipid phase state can produce acyl specificity in the tafazzin reaction but others have reported that tafazzin itself carries enzymatic specificity. To resolve this issue, we replicated and expanded the controversial experiments, i...
February 15, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28202237/bound-and-unbound-humic-acids-perform-different-roles-in-the-aggregation-and-deposition-of-multi-walled-carbon-nanotubes
#6
Xuezhi Yang, Qi Wang, Xiaolei Qu, Wei Jiang
Natural organic matter influences the carbon nanotube transport in aqueous environments. The role of bound humic acid (HA) on carbon nanotubes and unbound HA in bulk solution in the aggregation and deposition of carboxylated multi-walled carbon nanotubes (C-MWNTs) was examined in NaCl and CaCl2 electrolyte solution. Time-resolved dynamic light scattering and quartz crystal microbalance with dissipation monitoring were employed to investigate the C-MWNT aggregation and deposition kinetics, respectively. The critical coagulation concentration (CCC) of C-MWNTs is 30mM in NaCl and 3mM in CaCl2...
February 12, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28199767/alkaliphilic-bacillus-species-show-potential-application-in-concrete-crack-repair-by-virtue-of-rapid-spore-production-and-germination-then-extracellular-calcite-formation
#7
T K Sharma, M Alazhari, A Heath, K Paine, R M Cooper
AIMS: Characterisation of alkaliphilic Bacillus species for spore production and germination and calcite formation as a prelude to investigate their potential in micro-crack remediation in concrete. METHODS AND RESULTS: Conditions, extent and timing of endospore production was determined by dark field light microscopy; germination induction and kinetics was assessed by combining reduction in optical density with formation of refractile bodies by phase contrast microscopy...
February 15, 2017: Journal of Applied Microbiology
https://www.readbyqxmd.com/read/28199119/engineering-a-catalytically-efficient-recombinant-protein-ligase
#8
Renliang Yang, Yee Hwa Wong, Giang K T Nguyen, James P Tam, Julien Lescar, Bin Wu
Breaking and forming peptidyl bonds are fundamental biochemical reactions in protein chemistry. Unlike proteases that are abundantly available, fast-acting ligases are rare. OaAEP1 is an enzyme isolated from the cyclotide-producing plant oldenlandia affinis that displayed weak peptide cyclase activity, despite having a similar structural fold with other asparaginyl endopeptidases (AEP). Here we report the first atomic structure of OaAEP1, at a resolution of 2.56 Å, in its pre-activation form. Our structure and biochemical analysis of this enzyme reveals its activation mechanism as well as structural features important for its ligation activity...
February 15, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28199110/kinetics-of-hydrogen-abstraction-and-addition-reactions-of-3-hexene-by-%C3%A8-h-radicals
#9
Feiyu Yang, Fuquan Deng, Youshun Pan, Yingjia Zhang, Chenglong Tang, Zuohua Huang
Rate coefficients of H-atom abstraction and H-atom addition reactions of 3-hexene by the hydroxyl radicals were determined using both conventional transition-state theory and canonical variational transition-state theory, with potential energy surface (PES) evaluated at the CCSD(T)/CBS//BHandHLYP/6-311G (d, p) level and quantum mechanical effect corrected by the compounded methods including one-dimensional Wigner method, multi-dimensional zero-curvature tunneling method and small-curvature tunneling method...
February 15, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28199083/shape-memory-hydrogels-evolution-of-structural-principles-to-enable-shape-switching-of-hydrophilic-polymer-networks
#10
Candy Löwenberg, Maria Balk, Christian Wischke, Marc Behl, Andreas Lendlein
The ability of hydrophilic chain segments in polymer networks to strongly interact with water allows the volumetric expansion of the material and formation of a hydrogel. When polymer chain segments undergo reversible hydration depending on environmental conditions, smart hydrogels can be realized, which are able to shrink/swell and thus alter their volume on demand. In contrast, implementing the capacity of hydrogels to switch their shape rather than volume demands more sophisticated chemical approaches and structural concepts...
February 15, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28198896/size-dependent-stability-of-cobalt-nanoparticles-on-silica-under-high-conversion-fischer-tropsch-environment
#11
Moritz Wolf, Hendrik Kotzé, Nico Fischer, Michael Claeys
Highly monodisperse cobalt crystallites, supported on Stöber silica spheres, as model catalysts for the Fischer-Tropsch synthesis were exposed to simulated high conversion environments in the presence and absence of CO utilising an in house developed in situ magnetometer. The catalyst comprising the smallest crystallites in the metallic state (average diameter of 3.2 nm) experienced pronounced oxidation whilst the ratio of H2O to H2 was increased stepwise to simulate CO conversions from 26% up to complete conversion...
February 15, 2017: Faraday Discussions
https://www.readbyqxmd.com/read/28196892/modeling-the-two-way-feedback-between-contractility-and-matrix-realignment-reveals-a-nonlinear-mode-of-cancer-cell-invasion
#12
Hossein Ahmadzadeh, Marie R Webster, Reeti Behera, Angela M Jimenez Valencia, Denis Wirtz, Ashani T Weeraratna, Vivek B Shenoy
Cancer cell invasion from primary tumors is mediated by a complex interplay between cellular adhesions, actomyosin-driven contractility, and the physical characteristics of the extracellular matrix (ECM). Here, we incorporate a mechanochemical free-energy-based approach to elucidate how the two-way feedback loop between cell contractility (induced by the activity of chemomechanical interactions such as Ca(2+) and Rho signaling pathways) and matrix fiber realignment and strain stiffening enables the cells to polarize and develop contractile forces to break free from the tumor spheroids and invade into the ECM...
February 14, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28195901/prognostic-molecular-and-imaging-biomarkers-in-primary-glioblastoma
#13
Edit Bosnyák, Sharon K Michelhaugh, Neil V Klinger, David O Kamson, Geoffrey R Barger, Sandeep Mittal, Csaba Juhász
PURPOSE: Several molecular glioma markers (including isocitrate dehydrogenase 1 [IDH1] mutation, amplification of the epidermal growth factor receptor [EGFR], and methylation of the O6-methylguanine-DNA methyltransferase [MGMT] promoter) have been associated with glioblastoma survival. In this study, we examined the association between tumoral amino acid uptake, molecular markers, and overall survival in patients with IDH1 wild-type (primary) glioblastoma. PATIENTS AND METHODS: Twenty-one patients with newly diagnosed IDH1 wild-type glioblastomas underwent presurgical MRI and PET scanning with alpha[C-11]-L-methyl-tryptophan (AMT)...
February 14, 2017: Clinical Nuclear Medicine
https://www.readbyqxmd.com/read/28193064/vapor-pressure-isotope-effects-in-halogenated-organic-compounds-and-alcohols-dissolved-in-water
#14
Axel Horst, Georges Lacrampe-Couloume, Barbara Sherwood Lollar
Volatilization causes changes in the isotopic composition of organic compounds as a result of different vapor pressures of molecules containing heavy and light isotopes. Both normal and inverse vapor pressure isotope effects (VPIE) have been observed, depending on molecular interactions in the liquid phase and the investigated element. Previous studies have focused mostly on pure compound volatilization or on compounds dissolved in organic liquids. Environmentally relevant scenarios, such as isotope fractionation during volatilization of organics from open water surfaces, have largely been neglected...
December 20, 2016: Analytical Chemistry
https://www.readbyqxmd.com/read/28193017/single-particle-tracking-of-peptides-modified-nanocargo-on-lipid-membrane-revealing-bulk-mediated-diffusion
#15
Lin Wei, Zhongju Ye, Yueling Xu, Bo Chen, Edward S Yeung, Lehui Xiao
Understanding the detailed diffusion behavior of the nanocargo on lipid membrane can afford deep insight into the surface chemistry controlled translocation mechanism for the rational design of an efficient delivery system. By tracking the diffusion trajectory of transacting activator of transcription (TAT, a cell penetrating peptide) peptides-modified nanocargo on lipid membrane, bulk-mediated (intermittent hopping) diffusion was observed for the first time after a blended modification of TAT peptides and polyethylene glycol (PEG) molecules onto the nanoparticle surface...
December 20, 2016: Analytical Chemistry
https://www.readbyqxmd.com/read/28192761/a-comparison-of-bayesian-and-non-linear-regression-methods-for-robust-estimation-of-pharmacokinetics-in-dce-mri-and-how-it-affects-cancer-diagnosis
#16
Nikolaos Dikaios, David Atkinson, Chiara Tudisca, Pierpaolo Purpura, Martin Forster, Hashim Ahmed, Timothy Beale, Mark Emberton, Shonit Punwani
The aim of this work is to compare Bayesian Inference for nonlinear models with commonly used traditional non-linear regression (NR) algorithms for estimating tracer kinetics in Dynamic Contrast Enhanced Magnetic Resonance Imaging (DCE-MRI). The algorithms are compared in terms of accuracy, and reproducibility under different initialization settings. Further it is investigated how a more robust estimation of tracer kinetics affects cancer diagnosis. The derived tracer kinetics from the Bayesian algorithm were validated against traditional NR algorithms (i...
February 5, 2017: Computerized Medical Imaging and Graphics: the Official Journal of the Computerized Medical Imaging Society
https://www.readbyqxmd.com/read/28192542/functional-diversity-of-secreted-cestode-kunitz-proteins-inhibition-of-serine-peptidases-and-blockade-of-cation-channels
#17
Martín Fló, Mariana Margenat, Leonardo Pellizza, Martín Graña, Rosario Durán, Adriana Báez, Emilio Salceda, Enrique Soto, Beatriz Alvarez, Cecilia Fernández
We previously reported a multigene family of monodomain Kunitz proteins from Echinococcus granulosus (EgKU-1-EgKU-8), and provided evidence that some EgKUs are secreted by larval worms to the host interface. In addition, functional studies and homology modeling suggested that, similar to monodomain Kunitz families present in animal venoms, the E. granulosus family could include peptidase inhibitors as well as channel blockers. Using enzyme kinetics and whole-cell patch-clamp, we now demonstrate that the EgKUs are indeed functionally diverse...
February 13, 2017: PLoS Pathogens
https://www.readbyqxmd.com/read/28191004/ghrelin-reactive-immunoglobulins-in-conditions-of-altered-appetite-and-energy-balance
#18
REVIEW
Sergueï O Fetissov, Nicolas Lucas, Romain Legrand
Part of circulating ghrelin is bound to immunoglobulins (Ig) protecting it from degradation and preserving its functional activity. This review summarizes the data on ghrelin- and desacyl-ghrelin-reactive IgG in conditions of altered appetite and energy balance. Plasma levels and affinity kinetics of such IgG were compared in patients with obesity and anorexia nervosa (AN) and in animal models of obesity including ob/ob mice, high-fat diet-induced obese mice, and obese Zucker rats as well as in mice after chronic food restriction and activity-based anorexia and in rats with methotrexate-induced anorexia...
2017: Frontiers in Endocrinology
https://www.readbyqxmd.com/read/28188740/ph-dependent-properties-of-ion-channels-formed-by-n-terminally-glutamate-substituted-gramicidin-a-in-planar-lipid-bilayers
#19
Dmitry K Chistyulin, Tatyana I Rokitskaya, Sergey I Kovalchuk, Alexandra I Sorochkina, Alexander M Firsov, Elena A Kotova, Yuri N Antonenko
The N-terminally glutamate substituted analogue of the pentadecapeptide gramicidin A [Glu1]gA has been previously described as a low-toxic uncoupler of mitochondrial oxidative phosphorylation and neuroprotector. Here, we studied ion channel-forming activity of this peptide in planar bilayer lipid membranes (BLMs). [Glu1]gA exhibited an ability to induce both macroscopic current and single channels in a broad pH range, albeit with a lower potency than the parent gramicidin A (gA). Single-channel recordings in 1M KCl at pH about 4 showed channel openings of one type with the conductance (about 26pS), similar to that of gA, and the lifetime (40ms), much shorter than that of gA...
February 7, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28187315/reaction-of-tetracycline-with-biologically-relevant-chloramines
#20
J Benavides, P Barrias, N Piro, A Arenas, A Orrego, E Pino, L Villegas, E Dorta, A Aspée, C López-Alarcón
Helicobacter pylori (H. pylori) infection triggers inflammatory processes with the consequent production of hypochlorous acid (HOCl), monochloramine (NH2Cl), and protein-derived chloramines. As the therapy for eradicating H. pylori is partially based on the use of tetracycline, we studied the kinetic of its consumption elicited by HOCl, NH2Cl, N-chloro-n-butylamine (NHCl-But, used as a lysine-derived chloramine model), and lysozyme-derived chloramines. In the micromolar concentration range, tetracycline reacted rapidly with HOCl, generating in the first few seconds intermediates of short half-life...
February 4, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
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