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https://www.readbyqxmd.com/read/28938307/design-and-development-of-a-miniaturized-percutaneously-deployable-wireless-left-ventricular-assist-device-early-prototypes-and-feasibility-testing
#1
Brian Letzen, Jiheum Park, Zeynep Tuzun, Pramod Bonde
The current left ventricular assist devices (LVADs) are limited by a highly invasive implantation procedure in a severely unstable group of advanced heart failure patients. Additionally, the current transcutaneous power drive line acts as a nidus for infection resulting in significant morbidity and mortality. In an effort to decrease this invasiveness and eliminate drive line complications, we have conceived a wireless miniaturized percutaneous LVAD, capable of being delivered endovascularly with a tether-free operation...
September 21, 2017: ASAIO Journal: a Peer-reviewed Journal of the American Society for Artificial Internal Organs
https://www.readbyqxmd.com/read/28938147/development-of-an-experimental-model-of-burst-fracture-with-damage-characterization-of-the-vertebral-bodies-under-dynamic-conditions
#2
A Germaneau, T Vendeuvre, M Saget, P Doumalin, J C Dupré, F Brémand, F Hesser, C Brèque, P Maxy, M Roulaud, O Monlezun, P Rigoard
BACKGROUND: Burst fractures represent a significant proportion of fractures of the thoracolumbar junction. The recent advent of minimally invasive techniques has revolutionized the surgical treatment of this type of fracture. However mechanical behaviour and primary stability offered by these solutions have to be proved from experimental validation tests on cadaveric specimens. Therefore, the aim of this study was to develop an original and reproducible model of burst fracture under dynamic impact...
September 13, 2017: Clinical Biomechanics
https://www.readbyqxmd.com/read/28938079/comparing-climate-sensitivity-past-and-present
#3
Eelco J Rohling, Gianluca Marino, Gavin L Foster, Philip A Goodwin, Anna S von der Heydt, Peter Köhler
Climate sensitivity represents the global mean temperature change caused by changes in the radiative balance of climate; it is studied for both present/future (actuo) and past (paleo) climate variations, with the former based on instrumental records and/or various types of model simulations. Paleo-estimates are often considered informative for assessments of actuo-climate change caused by anthropogenic greenhouse forcing, but this utility remains debated because of concerns about the impacts of uncertainties, assumptions, and incomplete knowledge about controlling mechanisms in the dynamic climate system, with its multiple interacting feedbacks and their potential dependence on the climate background state...
September 22, 2017: Annual Review of Marine Science
https://www.readbyqxmd.com/read/28938073/transfer-learning-from-markov-models-leads-to-efficient-sampling-of-related-systems
#4
Mohammad Muneeb Sultan, Vijay S Pande
We recently showed that the time-structure based independent component analysis method from Markov state model literature provided a set of variationally optimal slow collective variables for Metadynamics (tICA-Metadynamics). In this paper, we extend the methodology towards efficient sampling of related mutants by borrowing ideas from transfer learning methods in machine learning. Our method explicitly assumes that a similar set of slow modes and metastable states are found in both the wild type (base line) and its mutants...
September 22, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28938009/altering-neuronal-excitability-to-preserve-network-connectivity-in-a-computational-model-of-alzheimer-s-disease
#5
Willem de Haan, Elisabeth C W van Straaten, Alida A Gouw, Cornelis J Stam
Neuronal hyperactivity and hyperexcitability of the cerebral cortex and hippocampal region is an increasingly observed phenomenon in preclinical Alzheimer's disease (AD). In later stages, oscillatory slowing and loss of functional connectivity are ubiquitous. Recent evidence suggests that neuronal dynamics have a prominent role in AD pathophysiology, making it a potentially interesting therapeutic target. However, although neuronal activity can be manipulated by various (non-)pharmacological means, intervening in a highly integrated system that depends on complex dynamics can produce counterintuitive and adverse effects...
September 22, 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28937994/modeling-of-annexin-a2-membrane-interactions-by-molecular-dynamics-simulations
#6
Davit Hakobyan, Volker Gerke, Andreas Heuer
The annexins are a family of Ca2+-regulated phospholipid binding proteins that are involved in membrane domain organization and membrane trafficking. Although they are widely studied and crystal structures are available for several soluble annexins their mode of membrane association has never been studied at the molecular level. Here we obtained molecular information on the annexin-membrane interaction that could serve as paradigm for the peripheral membrane association of cytosolic proteins by Molecular Dynamics simulations...
2017: PloS One
https://www.readbyqxmd.com/read/28937984/evidence-of-complex-contagion-of-information-in-social-media-an-experiment-using-twitter-bots
#7
Bjarke Mønsted, Piotr Sapieżyński, Emilio Ferrara, Sune Lehmann
It has recently become possible to study the dynamics of information diffusion in techno-social systems at scale, due to the emergence of online platforms, such as Twitter, with millions of users. One question that systematically recurs is whether information spreads according to simple or complex dynamics: does each exposure to a piece of information have an independent probability of a user adopting it (simple contagion), or does this probability depend instead on the number of sources of exposure, increasing above some threshold (complex contagion)? Most studies to date are observational and, therefore, unable to disentangle the effects of confounding factors such as social reinforcement, homophily, limited attention, or network community structure...
2017: PloS One
https://www.readbyqxmd.com/read/28937978/a-new-discrete-dynamic-model-of-aba-induced-stomatal-closure-predicts-key-feedback-loops
#8
Réka Albert, Biswa R Acharya, Byeong Wook Jeon, Jorge G T Zañudo, Mengmeng Zhu, Karim Osman, Sarah M Assmann
Stomata, microscopic pores in leaf surfaces through which water loss and carbon dioxide uptake occur, are closed in response to drought by the phytohormone abscisic acid (ABA). This process is vital for drought tolerance and has been the topic of extensive experimental investigation in the last decades. Although a core signaling chain has been elucidated consisting of ABA binding to receptors, which alleviates negative regulation by protein phosphatases 2C (PP2Cs) of the protein kinase OPEN STOMATA 1 (OST1) and ultimately results in activation of anion channels, osmotic water loss, and stomatal closure, over 70 additional components have been identified, yet their relationships with each other and the core components are poorly elucidated...
September 22, 2017: PLoS Biology
https://www.readbyqxmd.com/read/28937829/nonlinearity-coherence-and-complexity-biophysical-aspects-related-to-health-and-disease
#9
Alberto Foletti, Larissa Brizhik
Biological organisms are complex open dissipative systems whose dynamical stability is sustained due to the exchange of matter, energy and information. Dynamical stability occurs through a number of mechanisms that sustain efficient adaptive dynamics. Such properties of living matter can be the consequence of a self-consistent state of matter and electromagnetic field (EMF). Based on the soliton model of charge transport in redox processes, we describe a possible mechanism of the origin of endogenous EMF and coherence...
September 22, 2017: Electromagnetic Biology and Medicine
https://www.readbyqxmd.com/read/28937815/differential-allocation-revisited-when-should-mate-quality-affect-parental-investment
#10
Thomas R Haaland, Jonathan Wright, Bram Kuijper, Irja I Ratikainen
Differential allocation (DA) is the adaptive adjustment of reproductive investment (up or down) according to partner quality. A lack of theoretical treatments has led to some confusion in the interpretation of DA in the empirical literature. We present a formal framework for DA that highlights the nature of reproductive benefits versus costs for females mated to males of different quality. Contrary to popular belief, analytical and stochastic dynamic models both show that additive benefits of male quality on offspring fitness have no effect on optimal levels of female investment and thus cannot produce DA...
October 2017: American Naturalist
https://www.readbyqxmd.com/read/28937227/low-temperature-decoupling-of-water-and-protein-dynamics-measured-by-neutron-scattering
#11
Antonio Benedetto
Water plays a major role in bio-systems, greatly contributing to determine their structure, stability and function. It is well know, for instance, that proteins require a minimum amount of water to be fully functional. Despite many years of intensive research, however, the detailed nature of protein-hydration water interactions is still partly unknown. The widely-accepted "protein dynamical transition" scenario is based on perfect coupling between the dynamics of proteins and that of their hydration water, which has never been probed in depth experimentally...
September 22, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28936275/a-bio-inspired-method-for-direct-measurement-of-local-wall-shear-rates-with-micrometer-localization-using-the-multimeric-protein-von-willebrand-factor-as-sensor-molecule
#12
Klaus Bonazza, Bernhard Scheichl, Johannes Frank, Hanspeter Rottensteiner, Gerald Schrenk, Gernot Friedbacher, Peter L Turecek, Friedrich Scheiflinger, Günter Allmaier
Wall shear rates are critical for a broad variety of fluidic phenomena and are taken into account in nearly every experimental or simulation study. Generally, shear rates are not observable directly but rather derived from other parameters such as pressure and flow, often assuming somehow idealized systems. However, there is a biological system which is able to constantly measure the wall shear as a part of a regulatory circuit: The blood circulation system takes advantage of shear rate sensor (protein)molecules (multimeric forms of von Willebrand Factor, VWF), which are dissolved in the blood plasma and dramatically change their conformation under shear conditions...
July 2017: Biomicrofluidics
https://www.readbyqxmd.com/read/28936179/seasonal-variations-in-heart-rate-variability-as-an-indicator-of-stress-in-free-ranging-pregnant-przewalski-s-horses-e-ferus-przewalskii-within-the-hortob%C3%A3-gy-national-park-in-hungary
#13
Friederike Pohlin, Kristin Brabender, Gerhard Fluch, Gabrielle Stalder, Thierry Petit, Chris Walzer
Background: Ecosystems with seasonal fluctuations in climate and food availability present physiological challenges to resident mammals and may cause "stress." The two predominant physiological responses to stressors are (1) the activation of the hypothalamic-pituitary-adrenal axis and (2) the modulation of the autonomic nervous system. To date, the primary indicator for "stress" in wildlife- and zoo animal research are glucocorticoid levels. By measuring the autonomic regulation of cardiac activity, particularly the vagal tone, heart rate variability (HRV) is presently emerging as a suitable indicator of "stress" in farm- and domestic animal research...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28935896/network-heterogeneity-regulates-steering-in-actin-based-motility
#14
Rajaa Boujemaa-Paterski, Cristian Suarez, Tobias Klar, Jie Zhu, Christophe Guérin, Alex Mogilner, Manuel Théry, Laurent Blanchoin
The growth of branched actin networks powers cell-edge protrusions and motility. A heterogeneous density of actin, which yields to a tunable cellular response, characterizes these dynamic structures. We study how actin organization controls both the rate and the steering during lamellipodium growth. We use a high-resolution surface structuration assay combined with mathematical modeling to describe the growth of a reconstituted lamellipodium. We demonstrate that local monomer depletion at the site of assembly negatively impacts the network growth rate...
September 21, 2017: Nature Communications
https://www.readbyqxmd.com/read/28934501/model-based-design-of-rna-hybridization-networks-implemented-in-living-cells
#15
Guillermo Rodrigo, Satya Prakash, Shensi Shen, Eszter Majer, José-Antonio Daròs, Alfonso Jaramillo
Synthetic gene circuits allow the behavior of living cells to be reprogrammed, and non-coding small RNAs (sRNAs) are increasingly being used as programmable regulators of gene expression. However, sRNAs (natural or synthetic) are generally used to regulate single target genes, while complex dynamic behaviors would require networks of sRNAs regulating each other. Here, we report a strategy for implementing such networks that exploits hybridization reactions carried out exclusively by multifaceted sRNAs that are both targets of and triggers for other sRNAs...
September 19, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28934484/regulation-of-hur-structure-and-function-by-dihydrotanshinone-i
#16
Preet Lal, Linda Cerofolini, Vito Giuseppe D'Agostino, Chiara Zucal, Carmelo Fuccio, Isabelle Bonomo, Erik Dassi, Stefano Giuntini, Danilo Di Maio, Vikalp Vishwakarma, Ranjan Preet, Sha Neisha Williams, Max S Fairlamb, Rachel Munk, Elin Lehrmann, Kotb Abdelmohsen, Saioa R Elezgarai, Claudio Luchinat, Ettore Novellino, Alessandro Quattrone, Emiliano Biasini, Leonardo Manzoni, Myriam Gorospe, Dan A Dixon, Pierfausto Seneci, Luciana Marinelli, Marco Fragai, Alessandro Provenzani
The Human antigen R protein (HuR) is an RNA-binding protein that recognizes U/AU-rich elements in diverse RNAs through two RNA-recognition motifs, RRM1 and RRM2, and post-transcriptionally regulates the fate of target RNAs. The natural product dihydrotanshinone-I (DHTS) prevents the association of HuR and target RNAs in vitro and in cultured cells by interfering with the binding of HuR to RNA. Here, we report the structural determinants of the interaction between DHTS and HuR and the impact of DHTS on HuR binding to target mRNAs transcriptome-wide...
September 19, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28934283/grading-of-invasive-breast-carcinoma-through-grassmannian-vlad-encoding
#17
Kosmas Dimitropoulos, Panagiotis Barmpoutis, Christina Zioga, Athanasios Kamas, Kalliopi Patsiaoura, Nikos Grammalidis
In this paper we address the problem of automated grading of invasive breast carcinoma through the encoding of histological images as VLAD (Vector of Locally Aggregated Descriptors) representations on the Grassmann manifold. The proposed method considers each image as a set of multidimensional spatially-evolving signals that can be efficiently modeled through a higher-order linear dynamical systems analysis. Subsequently, each H&E (Hematoxylin and Eosin) stained breast cancer histological image is represented as a cloud of points on the Grassmann manifold, while a vector representation approach is applied aiming to aggregate the Grassmannian points based on a locality criterion on the manifold...
2017: PloS One
https://www.readbyqxmd.com/read/28934134/ferrocene-molecular-architectures-grafted-on-si-111-a-theoretical-calculation-of-the-standard-oxidation-potentials-and-electron-transfer-rate-constant
#18
Claudio Fontanesi, Massimo Innocenti, Davide Vanossi, Enrico Da Como
The standard oxidation potential and the electron transfer (ET) rate constants of two silicon-based hybrid interfaces, Si(111)/organic-spacer/Ferrocene, are theoretically calculated and assessed. The dynamics of the electrochemical driven ET process is modeled in terms of the classical donor/acceptor scheme within the framework of "Marcus theory". The ET rate constants, k E T , are determined following calculation of the electron transfer matrix element, V R P , together with the knowledge of the energy of the neutral and charge separated systems...
September 21, 2017: Materials
https://www.readbyqxmd.com/read/28933862/creim-coffee-ring-effect-imaging-model-for-monitoring-protein-self-assembly-in-situ
#19
Michael Shaw, Angelo Bella, Maxim G Ryadnov
Protein self-assembly is fundamental to nanotechnology. Self-assembling structures are produced under static in vitro conditions typically forming over hours. In contrast, hydrodynamic intracellular environments employ far shorter time scales to compartmentalize highly concentrated protein solutions. Herein, we exploit the radial capillary flow within a drying sessile droplet (the coffee ring effect) to emulate dynamic native environments and monitor an archetypal protein assembly in situ using high-speed super-resolution imaging...
September 22, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28933854/epigenetic-dna-modification-n6-methyladenine-causes-site-specific-rna-polymerase-ii-transcriptional-pausing
#20
Wei Wang, Liang Xu, Lulu Hu, Jenny Chong, Chuan He, Dong Wang
N6-methyladenine (N6-mA or 6mA) is an epigenetic DNA modification in eukaryotic genomes. In contrast to the well-established roles of 5-methylcytosine for epigenetic regulation of gene expression, the functional roles of N6-mA remain elusive. In particular, the impact of N6-mA modification at DNA template on RNA polymerase II (pol II) transcription elongation is not known. In this work, using the Saccharomyces cerevisiae pol II transcriptional elongation system as a model, we investigated the molecular mechanism of pol II recognition and processing of N6-mA sites via both biochemical and structural approaches...
September 21, 2017: Journal of the American Chemical Society
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