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https://www.readbyqxmd.com/read/29141181/axon-pathfinding-for-locomotion
#1
REVIEW
Dario Bonanomi
Motor neurons of the spinal cord are responsible for the assembly of neuromuscular connections indispensable for basic locomotion and skilled movements. A precise spatial relationship exists between the position of motor neuron cell bodies in the spinal cord and the course of their axonal projections to peripheral muscle targets. Motor neuron innervation of the vertebrate limb is a prime example of this topographic organization and by virtue of its accessibility and predictability has provided access to fundamental principles of motor system development and neuronal guidance...
November 12, 2017: Seminars in Cell & Developmental Biology
https://www.readbyqxmd.com/read/29133433/attention-priority-map-of-face-images-in-human-early-visual-cortex
#2
Ce Mo, Dongjun He, Fang Fang
Attention priority maps are topographic representations that are utilized for attention selection and guidance of task-related behavior during visual processing. Previous studies have identified attention priority maps of simple artificial stimuli in multiple cortical and subcortical areas, while investigating neural correlates of priority maps of natural stimuli is complicated by the complexity of their spatial structure and the difficulty of behaviorally characterizing their priority map. To overcome these challenges, we reconstructed the topographic representations of upright/invered face images from fMRI BOLD signals in human early visual areas V1-V3 based on a voxel-wise population receptive field model and behaviorally characterized the priority map as the first saccadic eye movement pattern when subjects performed a face matching task, relative to the condition in which subjects performed a phase-scrambled face matching task...
November 13, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/29096406/hydrogel-composition-and-laser-micro-patterning-to-regulate-sciatic-nerve-regeneration
#3
Yulia Berkovitch, Talia Cohen, Eli Peled, Robert Schmidhammer, Hildner Florian, Andreas Teuschl, Susanne Wolbank, Dvir Yelin, Heinz Redl, Dror Seliktar
Treatment of peripheral nerve injuries has evolved over the past several decades to include the use of sophisticated new materials endowed with trophic and topographical cues that are essential for in vivo nerve fiber regeneration. In this research, we explored the use of an advanced design strategy for peripheral nerve repair, using biological and semi-synthetic hydrogels that enable controlled environmental stimuli to regenerate neurons and glial cells in a rat sciatic nerve resection model. The provisional nerve growth conduits were comprised of either natural fibrin, or adducts of synthetic polyethylene glycol (PEG) and fibrinogen or gelatin...
November 2, 2017: Journal of Tissue Engineering and Regenerative Medicine
https://www.readbyqxmd.com/read/29043500/optimal-pacing-and-carbohydrate-intake-strategies-for-ultramarathons
#4
Kristopher A Pruitt, Justin M Hill
PURPOSE: The purpose of this research is to determine the pacing and nutrition strategies which minimize completion time and carbohydrate intake for athletes competing in ultramarathon races. METHODS: We present the formulation of a two-phase optimization model. The first-phase mixed-integer nonlinear program (MINLP) determines the minimum completion time subject to the altitude, terrain, and distance of the race, as well as the mass and cardiovascular fitness of the athlete...
October 17, 2017: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/29038581/transcriptional-repression-of-plxnc1-by-lmx1a-and-lmx1b-directs-topographic-dopaminergic-circuit-formation
#5
Audrey Chabrat, Guillaume Brisson, Hélène Doucet-Beaupré, Charleen Salesse, Marcos Schaan Profes, Axelle Dovonou, Cléophace Akitegetse, Julien Charest, Suzanne Lemstra, Daniel Côté, R Jeroen Pasterkamp, Monica I Abrudan, Emmanouil Metzakopian, Siew-Lan Ang, Martin Lévesque
Mesodiencephalic dopamine neurons play central roles in the regulation of a wide range of brain functions, including voluntary movement and behavioral processes. These functions are served by distinct subtypes of mesodiencephalic dopamine neurons located in the substantia nigra pars compacta and the ventral tegmental area, which form the nigrostriatal, mesolimbic, and mesocortical pathways. Until now, mechanisms involved in dopaminergic circuit formation remained largely unknown. Here, we show that Lmx1a, Lmx1b, and Otx2 transcription factors control subtype-specific mesodiencephalic dopamine neurons and their appropriate axon innervation...
October 16, 2017: Nature Communications
https://www.readbyqxmd.com/read/29028308/topographical-manipulation-of-microparticles-and-cells-with-acoustic-microstreaming
#6
Xiaolong Lu, Fernando Soto, Jinxing Li, Tianlong Li, Yuyan Liang, Joseph Wang
Precise and reproducible manipulation of synthetic and biological microscale objects in complex environments is essential for many practical biochip and microfluidic applications. Here, we present an attractive acoustic topographical manipulation (ATM) method to achieve efficient and reproducible manipulation of diverse microscale objects. This new guidance method relies on the acoustically induced localized microstreaming forces generated around microstructures, which are capable of trapping nearby microobjects and manipulating them along a determined trajectory based on local topographic features...
November 8, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28927933/azopolymer-photopatterning-for-directional-control-of-angiogenesis
#7
Chiara Fedele, Maria De Gregorio, Paolo A Netti, Silvia Cavalli, Chiara Attanasio
Understanding cellular behavior in response to microenvironmental stimuli is central to tissue engineering. An increasing number of reports emphasize the high sensitivity of cells to the physical characteristics of the surrounding milieu and in particular, topographical cues. In this work, we investigated the influence of dynamic topographic signal presentation on sprout formation and the possibility to obtain a space-time control over sprouting directionality without growth factors, in order to investigate the contribution of just topography in the angiogenic process...
November 2017: Acta Biomaterialia
https://www.readbyqxmd.com/read/28841276/tuning-surface-and-topographical-features-to-investigate-competitive-guidance-of-spiral-ganglion-neurons
#8
Braden L Leigh, Kristy Truong, Reid Bartholomew, Mark Ramirez, Marlan R Hansen, C Allan Guymon
Cochlear Implants (CIs) suffer from limited tonal resolution due, in large part, to spatial separation between stimulating electrode arrays and primary neural receptors. In this work, a combination of physical and chemical micropatterns, formed on acrylate polymers, are used to direct the growth of primary spiral ganglion neurons (SGNs), the inner ear neurons. Utilizing the inherent temporal and spatial control of photopolymerization, physical microgrooves are fabricated using a photomask in a single step process...
September 20, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28815971/topographical-and-electrical-stimulation-of-neuronal-cells-through-microwrinkled-conducting-polymer-biointerfaces
#9
Alberto Bonisoli, Attilio Marino, Gianni Ciofani, Francesco Greco
The development of smart biointerfaces combining multiple functions is crucial for triggering a variety of cellular responses. In this work, wrinkled organic interfaces based on the conducting polymer poly(3,4-ethylene dioxythiophene) doped with poly(styrene sulfonate) are developed with the aim to simultaneously convey electrical and topographical stimuli to cultured cells. The surface wrinkling of thin films on heat-shrink polymer sheets allows for rapid patterning of self-assembled anisotropic topographies characterized by micro/sub-microscale aligned wrinkles...
November 2017: Macromolecular Bioscience
https://www.readbyqxmd.com/read/28813592/3d-printed-phema-materials-for-topographical-and-biochemical-modulation-of-dorsal-root-ganglion-cell-response
#10
Adina Badea, Joselle M McCracken, Emily G Tillmaand, Mikhail E Kandel, Aaron W Oraham, Molly B Mevis, Stanislav S Rubakhin, Gabriel Popescu, Jonathan V Sweedler, Ralph G Nuzzo
Understanding and controlling the interactions occurring between cells and engineered materials are central challenges toward progress in the development of biomedical devices. In this work, we describe materials for direct ink writing (DIW), an extrusion-based type of 3D printing, that embed a custom synthetic protein (RGD-PDL) within the microfilaments of 3D-hydrogel scaffolds to modify these interactions and differentially direct tissue-level organization of complex cell populations in vitro. The RGD-PDL is synthesized by modifying poly-d-lysine (PDL) to varying extents with peptides containing the integrin-binding motif Arg-Gly-Asp (RGD)...
September 13, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28805664/correlation-and-comparison-of-cortical-and-hippocampal-neural-progenitor-morphology-and-differentiation-through-the-use-of-micro-and-nano-topographies
#11
Sharvari Sathe, Xiang Quan Chan, Jing Jin, Erik Bernitt, Hans-Günther Döbereiner, Evelyn K F Yim
Neuronal morphology and differentiation have been extensively studied on topography. The differentiation potential of neural progenitors has been shown to be influenced by brain region, developmental stage, and time in culture. However, the neurogenecity and morphology of different neural progenitors in response to topography have not been quantitatively compared. In this study, the correlation between the morphology and differentiation of hippocampal and cortical neural progenitor cells was explored. The morphology of differentiated neural progenitors was quantified on an array of topographies...
August 12, 2017: Journal of Functional Biomaterials
https://www.readbyqxmd.com/read/28792499/revisiting-chemoaffinity-theory-chemotactic-implementation-of-topographic-axonal-projection
#12
Honda Naoki
Neural circuits are wired by chemotactic migration of growth cones guided by extracellular guidance cue gradients. How growth cone chemotaxis builds the macroscopic structure of the neural circuit is a fundamental question in neuroscience. I addressed this issue in the case of the ordered axonal projections called topographic maps in the retinotectal system. In the retina and tectum, the erythropoietin-producing hepatocellular (Eph) receptors and their ligands, the ephrins, are expressed in gradients. According to Sperry's chemoaffinity theory, gradients in both the source and target areas enable projecting axons to recognize their proper terminals, but how axons chemotactically decode their destinations is largely unknown...
August 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28758545/a-topographical-map-approach-to-representing-treatment-efficacy-a-focus-on-positive-psychology-interventions
#13
Eugenia I Gorlin, Josephine Lee, Michael W Otto
A recent meta-analysis by Bolier et al. indicated that positive psychology interventions have overall small to moderate effects on well-being, but results were quite heterogeneous across intervention trials. Such meta-analytic research helps condense information on the efficacy of a broad psychosocial intervention by averaging across many effects; however, such global averages may provide limited navigational guidance for selecting among specific interventions. Here, we introduce a novel method for displaying qualitative and quantitative information on the efficacy of interventions using a topographical map approach...
July 31, 2017: Cognitive Behaviour Therapy
https://www.readbyqxmd.com/read/28722651/ephrin-a-epha-specific-co-adaptation-as-a-novel-mechanism-in-topographic-axon-guidance
#14
Felix Fiederling, Markus Weschenfelder, Martin Fritz, Anne von Philipsborn, Martin Bastmeyer, Franco Weth
Genetic hardwiring during brain development provides computational architectures for innate neuronal processing. Thus, the paradigmatic chick retinotectal projection, due to its neighborhood preserving, topographic organization, establishes millions of parallel channels for incremental visual field analysis. Retinal axons receive targeting information from quantitative guidance cue gradients. Surprisingly, novel adaptation assays demonstrate that retinal growth cones robustly adapt towards ephrin-A/EphA forward and reverse signals, which provide the major mapping cues...
July 19, 2017: ELife
https://www.readbyqxmd.com/read/28671108/cell-instructive-high-resolution-micropatterned-polylactic-acid-surfaces
#15
David Barata, Paulo Dias, Paul Wieringa, Clemens van Blitterswijk, Pamela Habibovic
Micro and nanoscale topographical structuring of biomaterial surfaces has been a valuable tool for influencing cell behavior, including cell attachment, proliferation and differentiation. However, most fabrication techniques for surface patterning of implantable biomaterials suffer from a limited resolution, not allowing controlled generation of sub-cellular three-dimensional features. Here, a direct laser lithography technique based on two-photon absorption was used to construct several patterns varying in size between 500 nm and 15 μm...
July 24, 2017: Biofabrication
https://www.readbyqxmd.com/read/28664962/initial-contact-guidance-during-cell-spreading-is-contractility-independent
#16
Adrià Sales, Andrew W Holle, Ralf Kemkemer
A wide variety of cell types exhibit substrate topography-based behavior, also known as contact guidance. However, the precise cellular mechanisms underlying this process are still unknown. In this study, we investigated contact guidance by studying the reaction of human endothelial cells (ECs) to well-defined microgroove topographies, both during and after initial cell spreading. As the cytoskeleton plays a major role in cellular adaptation to topographical features, two methods were used to perturb cytoskeletal structures...
August 2, 2017: Soft Matter
https://www.readbyqxmd.com/read/28653527/insights-into-the-silver-reflection-layer-of-a-vertical-led-for-light-emission-optimization
#17
Mansoor Ali Khan, Hansheng Chen, Jiangtao Qu, Patrick W Trimby, Steven Moody, Yin Yao, Simon P Ringer, Rongkun Zheng
In this work, Ag as a highly reflective mirror layer of gallium nitride (GaN)-based blue vertical light-emitting diodes (VLEDs) has been systematically investigated by correlating scanning electron microscopy/energy dispersive X-ray spectroscopy/transmission Kikuchi diffraction/electron backscatter diffraction, aberration-corrected scanning transmission electron microscopy, and atomic force microscopy techniques. In the context of high-efficiency lighting, three critical aspects have been scrutinized on the nanoscale: (1) chemical diffusion, (2) grain morphology, and (3) surface topography of the Ag layer...
July 19, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28509381/topography-guided-control-of-local-migratory-behaviors-and-protein-expression-of-cancer-cells
#18
Jung-Youn Shin, Hong Nam Kim, Suk Ho Bhang, Jeong-Kee Yoon, Kahp-Yang Suh, Noo Li Jeon, Byung-Soo Kim
In vivo cancer cell migration and invasion are directed by biophysical guidance mechanisms such as pre-existing microtracks and basement membrane extracellular matrices. Here, this paper reports the correlation of the local migratory behavior of cancer cells and the biochemical signal expression using the topography that can guide or inhibit cell behaviors. To this end, the local apparent migration and the protein expression level are investigated with respect to the topographical feature size (flat, nanoline, and microline) and orientation (microline, microconcentric, and microradial) with the collectively migrating (A431) and individually migrating (MDA-MB-231 and U-87-MG) cancer cells...
August 2017: Advanced Healthcare Materials
https://www.readbyqxmd.com/read/28462069/silicon-microgrooves-for-contact-guidance-of-human-aortic-endothelial-cells
#19
Sara Fernández-Castillejo, Pilar Formentín, Úrsula Catalán, Josep Pallarès, Lluís F Marsal, Rosa Solà
Background: Micro- and nanoscale substrates have been fabricated in order to study the influence of the topography on the cellular response. The aim of this work was to prepare different collagen-coated silicon substrates displaying grooves and ridges to mimic the aligned and elongated endothelium found in linear vessels, and to use them as substrates to study cell growth and behaviour. Results: The influence of groove-shaped substrates on cell adhesion, morphology and proliferation were assessed, by comparing them to flat silicon substrates, used as control condition...
2017: Beilstein Journal of Nanotechnology
https://www.readbyqxmd.com/read/28450099/topographical-anatomy-of-the-distal-ulna-attachment-of-the-radioulnar-ligament
#20
Won-Jeong Shin, Jong-Pil Kim, Hun-Mu Yang, Eun-Young Lee, Jai-Hyang Go, Kang Heo
PURPOSE: The deep component of the distal radioulnar ligament provides translational stability and rotational guidance to the forearm. However, controversy exists regarding the importance of this structure as well as the nature of its attachment to the distal ulna. We aimed to evaluate the topographic anatomy of the distal ulna attachment of both the superficial and the deep components of the radioulnar ligament and to assess the relationship between its internal and its external morphometry...
April 25, 2017: Journal of Hand Surgery
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