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https://www.readbyqxmd.com/read/28722651/ephrin-a-epha-specific-co-adaptation-as-a-novel-mechanism-in-topographic-axon-guidance
#1
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
#2
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
#3
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...
June 30, 2017: Soft Matter
https://www.readbyqxmd.com/read/28653527/insights-into-the-silver-reflection-layer-of-a-vertical-led-for-light-emission-optimization
#4
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
#5
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...
May 16, 2017: Advanced Healthcare Materials
https://www.readbyqxmd.com/read/28462069/silicon-microgrooves-for-contact-guidance-of-human-aortic-endothelial-cells
#6
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
#7
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
https://www.readbyqxmd.com/read/28438183/semaphorin-plexin-signaling-influences-early-ventral-telencephalic-development-and-thalamocortical-axon-guidance
#8
Manuela D Mitsogiannis, Graham E Little, Kevin J Mitchell
BACKGROUND: Sensory processing relies on projections from the thalamus to the neocortex being established during development. Information from different sensory modalities reaching the thalamus is segregated into specialized nuclei, whose neurons then send inputs to cognate cortical areas through topographically defined axonal connections. Developing thalamocortical axons (TCAs) normally approach the cortex by extending through the subpallium; here, axonal navigation is aided by distributed guidance cues and discrete cell populations, such as the corridor neurons and the internal capsule (IC) guidepost cells...
April 24, 2017: Neural Development
https://www.readbyqxmd.com/read/28437614/engineering-highly-interconnected-neuronal-networks-on-nanowire-scaffolds
#9
Vini Gautam, Shagufta Naureen, Naeem Shahid, Qian Gao, Yi Wang, David Nisbet, Chennupati Jagadish, Vincent R Daria
Identifying the specific role of physical guidance cues in the growth of neurons is crucial for understanding the fundamental biology of brain development and for designing scaffolds for tissue engineering. Here, we investigate the structural significance of nanoscale topographies as physical cues for neurite outgrowth and circuit formation by growing neurons on semiconductor nanowires. We monitored neurite growth using optical and scanning electron microscopy and evaluated the spontaneous neuronal network activity using functional calcium imaging...
June 14, 2017: Nano Letters
https://www.readbyqxmd.com/read/28401884/anisotropic-forces-from-spatially-constrained-focal-adhesions-mediate-contact-guidance-directed-cell-migration
#10
Arja Ray, Oscar Lee, Zaw Win, Rachel M Edwards, Patrick W Alford, Deok-Ho Kim, Paolo P Provenzano
Directed migration by contact guidance is a poorly understood yet vital phenomenon, particularly for carcinoma cell invasion on aligned collagen fibres. We demonstrate that for single cells, aligned architectures providing contact guidance cues induce constrained focal adhesion maturation and associated F-actin alignment, consequently orchestrating anisotropic traction stresses that drive cell orientation and directional migration. Consistent with this understanding, relaxing spatial constraints to adhesion maturation either through reduction in substrate alignment density or reduction in adhesion size diminishes the contact guidance response...
April 12, 2017: Nature Communications
https://www.readbyqxmd.com/read/28296389/abrogated-cell-contact-guidance-on-amino-functionalized-microgrooves
#11
Caroline Mörke, Henrike Rebl, Birgit Finke, Manuela Dubs, Peter Nestler, Aissam Airoudj, Vincent Roucoules, Matthias Schnabelrauch, Andreas Körtge, Karine Anselme, Christiane A Helm, J Barbara Nebe
Topographical and chemical features of biomaterial surfaces affect the cell physiology at the interface and are promising tools for the improvement of implants. The dominance of the surface topography on cell behavior is often accentuated. Striated surfaces induce an alignment of cells and their intracellular adhesion-mediated components. Recently, it could be demonstrated that a chemical modification via plasma polymerized allylamine was not only able to boost osteoblast cell adhesion and spreading but also override the cell alignment on stochastically machined titanium...
March 29, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28253620/conjugation-in-escherichia-coli-biofilms-on-poly-dimethylsiloxane-surfaces-with-microtopographic-patterns
#12
Huan Gu, Kristopher W Kolewe, Dacheng Ren
Bacterial biofilms are highly tolerant to antimicrobials and play an important role in the development and spread of antibiotic resistance based on horizontal gene transfer due to close cell-to-cell contact. As an important surface property, topography has been shown to affect bacterial adhesion and biofilm formation. Here, we demonstrate that micrometer-scale surface topographies also affect horizontal gene transfer through conjugation in bacterial biofilms. Specifically, biofilm formation and associated conjugation on poly(dimethylsiloxane) (PDMS) surfaces with 10 μm tall protruding patterns were studied using fluorescently labeled donor and recipient strains of Escherichia coli...
March 13, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28218340/world-health-organization-global-disability-action-plan-the-mongolian-perspective
#13
Fary Khan, Bhasker Amatya, Baljnnyam Avirmed, Yoon Kyoung Yi, Batchimeg Shirmen, Geoff Abbott, Mary P Galea
OBJECTIVE: To provide an update on disability and rehabilitation in Mongolia, and to identify potential barriers and facilitators for implementation of the World Health Organization (WHO) Global Disability Action Plan (GDAP). METHODS: A 4-member rehabilitation team from the Royal Melbourne Hospital conducted an intensive 6-day workshop at the Mongolian National University of Medical Sciences, for local healthcare professionals (n = 77) from medical rehabilitation facilities (urban/rural, public/private) and non-governmental organizations...
February 16, 2017: Journal of Rehabilitation Medicine
https://www.readbyqxmd.com/read/28197551/ephrina5-signaling-is-required-for-the-distinctive-targeting-of-raphe-serotonin-neurons-in-the-forebrain
#14
Teng Teng, Afsaneh Gaillard, Aude Muzerelle, Patricia Gaspar
Serotonin (5-HT) neurotransmission in the brain relies on a widespread axon terminal network originating from the hindbrain raphe nuclei. These projections are topographically organized such that the dorsal (DR), and median raphe (MnR) nuclei have different brain targets. However, the guidance molecules involved in this selective targeting in development are unknown. Here, we show the implication of ephrinA5 signaling in this process. We find that the EphA5 gene is selectively expressed in a subset of 5-HT neurons during embryonic and postnatal development...
January 2017: ENeuro
https://www.readbyqxmd.com/read/28193234/differential-timing-of-neurogenesis-underlies-dorsal-ventral-topographic-projection-of-olfactory-sensory-neurons
#15
Eerdunfu, Naoki Ihara, Bao Ligao, Yuji Ikegaya, Haruki Takeuchi
BACKGROUND: The mammalian primary olfactory system has a spatially-ordered projection in which olfactory sensory neurons (OSNs) located in the dorsomedial (DM) and ventrolateral (VL) region of the olfactory epithelium (OE) send their axons to the dorsal and ventral region of the olfactory bulb (OB), respectively. We previously found that OSN axonal projections occur sequentially, from the DM to the VL region of the OE. The differential timing of axonal projections is important for olfactory map formation because early-arriving OSN axons secrete guidance cues at the OB to help navigate late-arriving OSN axons...
February 13, 2017: Neural Development
https://www.readbyqxmd.com/read/28159617/a-brief-comparative-review-of-primate-posterior-parietal-cortex-a-novel-hypothesis-on-the-human-toolmaker
#16
S Kastner, Q Chen, S K Jeong, R E B Mruczek
The primate visual system contains two major cortical pathways: a ventral-temporal pathway that has been associated with object processing and recognition, and a dorsal-parietal pathway that has been associated with spatial processing and action guidance. Our understanding of the role of the dorsal pathway, in particular, has greatly evolved within the framework of the two-pathway hypothesis since its original conception. Here, we present a comparative review of the primate dorsal pathway in humans and monkeys based on electrophysiological, neuroimaging, neuropsychological, and neuroanatomical studies...
January 31, 2017: Neuropsychologia
https://www.readbyqxmd.com/read/28140524/micropatterning-of-reagent-free-high-energy-crosslinked-gelatin-hydrogels-for-bioapplications
#17
Benedikt Heyart, Astrid Weidt, Emilia I Wisotzki, Mareike Zink, Stefan G Mayr
Hydrogels are crosslinked polymeric gels of great interest in the field of tissue engineering, particularly as biocompatible cell or drug carriers. Reagent-free electron irradiated gelatin is simple to manufacture, inexpensive and biocompatible. Here, the potential to micropattern gelatin hydrogel surfaces during electron irradiation crosslinking was demonstrated as a promising microfabrication technique to produce thermally stable structures on highly relevant length scales for bioapplications. In the present work, grooves of 3...
January 31, 2017: Journal of Biomedical Materials Research. Part B, Applied Biomaterials
https://www.readbyqxmd.com/read/28109776/semaphorin-6a-knockout-mice-display-abnormalities-across-ethologically-based-topographies-of-exploration-and-in-motor-learning
#18
Kerstin Håkansson, Annette E Runker, Gerard J O'Sullivan, Kevin J Mitchell, John L Waddington, Colm M P O'Tuathaigh
Semaphorins are secreted or membrane-bound proteins implicated in neurodevelopmental processes of axon guidance and cell migration. Exploratory behaviour and motor learning was examined ethologically in Semaphorin 6A (Sema6A) mutant mice. The ethogram of initial exploration in Sema6A knockout mice was characterised by increased rearing to wall with decreased sifting; over subsequent habituation, locomotion, sniffing and rearing to wall were increased, with reduced habituation of rearing seated. Rotarod analysis indicated delayed motor learning in Sema6A heterozygous mutants...
January 18, 2017: Neuroscience Letters
https://www.readbyqxmd.com/read/28041615/functional-anatomy-of-the-macaque-temporo-parieto-frontal-connectivity
#19
REVIEW
Elena Borra, Giuseppe Luppino
The primate parietal lobe is primarily dedicated to the processing of sensory information for the guidance of motor behavior, based on the integration of sensory with motor signals (sensorimotor transformations), mediated by specific, strong, and reciprocal connections with the motor cortex. Sensorimotor transformations have been regarded as an automatic process carried out independently from the temporal cortex, which is considered the location where sensory information is used for perceptual processes. However, both human and non-human primate studies have shown interactions between these two regions in different aspects of sensorimotor and cognitive processes...
December 18, 2016: Cortex; a Journal Devoted to the Study of the Nervous System and Behavior
https://www.readbyqxmd.com/read/27974617/hermes-regulates-axon-sorting-in-the-optic-tract-by-post-trancriptional-regulation-of-neuropilin-1
#20
Hanna Hörnberg, Jean-Michel Cioni, William A Harris, Christine E Holt
The establishment of precise topographic maps during neural development is facilitated by the presorting of axons in the pathway before they reach their targets. In the vertebrate visual system, such topography is seen clearly in the optic tract (OT) and in the optic radiations. However, the molecular mechanisms involved in pretarget axon sorting are poorly understood. Here, we show in zebrafish that the RNA-binding protein Hermes, which is expressed exclusively in retinal ganglion cells (RGCs), is involved in this process...
December 14, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
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