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Growth cone

Lea Lepelletier, Sébastien D Langlois, Christopher B Kent, Kristy Welshhans, Steves Morin, Gary J Bassell, Patricia T Yam, Frédéric Charron
: Sonic hedgehog (Shh) attracts spinal cord commissural axons toward the floorplate. How Shh elicits changes in the growth cone cytoskeleton that drive growth cone turning is unknown. We find that the turning of rat commissural axons up a Shh gradient requires protein synthesis. In particular, Shh stimulation increases β-actin protein at the growth cone, even when the cell bodies have been removed. Thus Shh induces the local translation of β-actin at the growth cone. We hypothesised that this requires zipcode binding protein 1 (ZBP1), an mRNA binding protein that transports β-actin mRNA and releases it for local translation upon phosphorylation...
January 10, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Patrick C Kerstein, Kevin M Patel, Timothy M Gomez
: Guidance of axons to their proper synaptic target sites requires spatially and temporally precise modulation of biochemical signals within growth cones. Ionic calcium (Ca(2+)) is an essential signal for axon guidance that mediates opposing affects on growth cone motility. The diverse effects of Ca(2+) arise from the precise localization of Ca(2+) signals into microdomains containing specific Ca(2+) effectors. For example, differences in the mechanical and chemical composition of the underlying substrata elicit local Ca(2+) signals within growth cone filopodia that regulate axon guidance through activation of the protease calpain...
January 9, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
B Walker, J Radtke, G Petry, R Swader, G Chen, K Eliceiri, T Mackie
PURPOSE: To develop and build a practical implementation of an x-ray line source for the rapidly increasing number of multi-source imaging applications in CT. METHODS: An innovative x-ray tube was designed using CST Particle Studio, ANSYS, and SolidWorks. A slowly varying magnetic field is synchronized with microsecond gating of multiple thermionic electron sources. Electrostatic simulations were run to optimize the geometry of the optics and prevent electrode arcing...
June 2016: Medical Physics
Yadiel Sánchez, Arash Anvari, Anthony E Samir, Ronald S Arellano, Anand M Prabhakar, Raul N Uppot
Image-guided biopsy and ablation relies on successful identification and targeting of lesions. Currently, image-guided procedures are routinely performed under ultrasound, fluoroscopy, magnetic resonance imaging, or computed tomography (CT) guidance. However, these modalities have their limitations including inadequate visibility of the lesion, lesion or organ or patient motion, compatibility of instruments in an magnetic resonance imaging field, and, for CT and fluoroscopy cases, radiation exposure. Recent advances in technology have resulted in the development of a new generation of navigational guidance tools that can aid in targeting lesions for biopsy or ablations...
November 10, 2016: Current Problems in Diagnostic Radiology
Fatma Fayez Badr, Mark Mintline, Axel Ruprecht, Donald Cohen, Barton R Blumberg, Madhu K Nair
To our knowledge, the imaging features of costochondral grafts (CCGs) on cone-beam computed tomography (CBCT) have not been documented in the literature. We present the case of a CCG in the facial soft tissue to the anterior mandible, with changes mimicking a cartilaginous neoplasm. This is the first report to describe the CBCT imaging features of a long-standing graft in the anterior mandible. Implants or grafts may be incidental findings on radiographic images made for unrelated purposes. Although most are well-defined and radiographically homogeneous, being of relatively inert non-biological material, immune reactions to some grafts may stimulate alterations in the appearance of surrounding tissues...
December 2016: Imaging Science in Dentistry
Pablo José Barrecheguren, Oriol Ros, Tiziana Cotrufo, Beat Kunz, Eduardo Soriano, Fausto Ulloa, Esther T Stoeckli, Sofia J Araújo
Axonal growth and guidance rely on correct growth cone responses to guidance cues, both in the central nervous system (CNS) and in the periphery. Unlike the signaling cascades that link axonal growth to cytoskeletal dynamics, little is known about the crosstalk mechanisms between guidance and membrane dynamics and turnover in the axon. Our studies have shown that Netrin-1/Deleted in Colorectal Cancer (DCC) signaling triggers exocytosis through the SNARE Syntaxin-1 (STX-1) during the formation of commissural pathways...
December 29, 2016: Developmental Neurobiology
S L Smith, P H Buschang, P C Dechow
Maxillary sinus volumetric and surface area data and growth models from longitudinal samples of children and adolescents are presented. Cone-beam radiographic CT scans from two small retrospective longitudinal samples, one from the Baylor College of Dentistry, Dallas, TX (N=17, 12 females, 5 males, 10.9-17.4 years) and one from a group private orthodontic practice in Nevada (N=15, 9 females, 6 males, 6.4-13.4 years) were used to collect maxillary sinus volumes and surface areas from each individual imaged at two times separated by variable intervals...
November 4, 2016: Homo: Internationale Zeitschrift Für die Vergleichende Forschung Am Menschen
Maurizio De Crescenzi, Isabelle Berbezier, Manuela Scarselli, Paola Castrucci, Marco Abbarchi, Antoine Ronda, Fatme Jardali, Jejune Park, Holger Vach
The extraordinary properties of graphene have spurred huge interest in the experimental realization of a two-dimensional honeycomb lattice of silicon, namely, silicene. However, its synthesis on supporting substrates remains a challenging issue. Recently, strong doubts against the possibility of synthesizing silicene on metallic substrates have been brought forward because of the non-negligible interaction between silicon and metal atoms. To solve the growth problems, we directly deposited silicon on a chemically inert graphite substrate at room temperature...
December 27, 2016: ACS Nano
Sung Min Han, Huma S Baig, Marc Hammarlund
Axon regeneration is essential to restore the nervous system after axon injury. However, the neuronal cell biology that underlies axon regeneration is incompletely understood. Here we use in vivo, single-neuron analysis to investigate the relationship between nerve injury, mitochondrial localization, and axon regeneration. Mitochondria translocate into injured axons so that average mitochondria density increases after injury. Moreover, single-neuron analysis reveals that axons that fail to increase mitochondria have poor regeneration...
December 21, 2016: Neuron
Shouta Sugio, Masami Nagasawa, Itaru Kojima, Yasuki Ishizaki, Koji Shibasaki
We have previously reported that transient receptor potential vanilloid 2 (TRPV2) can be activated by mechanical stimulation, which enhances axonal outgrowth in developing neurons; however, the molecular mechanisms that govern the contribution of TRPV2 activation to axonal outgrowth remain unclear. In the present study, we examined this mechanism by using PC12 cells as a neuronal model. Overexpression of TRPV2 enhanced axonal outgrowth in a mechanical stimulus-dependent manner. Accumulation of TRPV2 at the cell surface was 4-fold greater in the growth cone compared with the soma...
December 22, 2016: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
Christian Siebold, Toshihide Yamashita, Philippe P Monnier, Bernhard K Mueller, R Jeroen Pasterkamp
Although originally discovered as neuronal growth cone-collapsing factors, repulsive guidance molecules (RGMs) are now known as key players in many fundamental processes, such as cell migration, differentiation, iron homeostasis, and apoptosis, during the development and homeostasis of many tissues and organs, including the nervous, skeletal, and immune systems. Furthermore, three RGMs (RGMa, RGMb/DRAGON, and RGMc/hemojuvelin) have been linked to the pathogenesis of various disorders ranging from multiple sclerosis (MS) to cancer and juvenile hemochromatosis (JHH)...
December 19, 2016: Trends in Cell Biology
David T Stark, Joseph Caprioli
Purpose: To investigate whether the subcellular distribution of endocannabinoid (eCB) system (ECS) components in growing RGC axons is consistent with the formation of eCB-enriched "hotspots" and the role of the ECS in RGC axonal growth. Methods: We used immunocytochemistry and image analysis to quantify axonal expression of the ECS components diacylglycerol lipase alpha (DGLα), monoacylglycerol lipase (MGL), and cannabinoid receptor type 1 (CB1R) in a mouse retinal explant model...
December 1, 2016: Investigative Ophthalmology & Visual Science
Nicholas J Batty, Keith K Fenrich, Karim Fouad
Injured neurons in the adult mammalian central nervous system (CNS) have a very limited capacity for axonal regeneration and neurite outgrowth. This inability to grow new axons or to regrow injured axons is due to the presence of molecules that inhibit axonal growth, and age related changes in the neuron's innate growth capabilities. Available levels of cAMP are thought to have an important role in linking both of these factors. Elevated levels of cAMP in the developing nervous system are important for the guidance and stability of growth cones...
December 15, 2016: Neuroscience Letters
Bin Deng, Liya Li, Xingchun Gou, Hao Xu, Zhaohua Zhao, Qiang Wang, Lixian Xu
Paired immunoglobulin-like receptor B (PirB) has been identified as a new receptor for myelin-associated inhibitory (MAI) proteins, which may play important role in axonal regeneration and corticospinal tract (CST) projection associated with neurobehavioral function recovery after stroke. Here, we found that the expression of PirB was increased in the cortical penumbra from 1 to 28 days after transient focal cerebral ischemic reperfusion of rats. Then, transactivator of transcription-PirB extracellular peptide (TAT-PEP) was generated that might block the interactions between MAIs and PirB...
December 16, 2016: Molecular Neurobiology
Paola Merino, Ariel Diaz, Valerie Jeanneret, Fang Wu, Enrique Torre, Lihong Cheng, Manuel Yepes
Axonal injury is a common cause of neurological dysfunction. Unfortunately, in contrast to axons from the peripheral nervous system, the limited capacity of regeneration of central nervous system (CNS) axons is a major obstacle for functional recovery in patients suffering neurological diseases that involve the subcortical white matter. Urokinase-type plasminogen activator (uPA) is a serine proteinase that upon binding to the urokinase-type plasminogen activator receptor (uPAR) catalyzes the conversion of plasminogen into plasmin on the cell surface...
December 16, 2016: Journal of Biological Chemistry
Timothy J Gawne, John T Siegwart, Alexander H Ward, Thomas T Norton
Shortly after birth, the eyes of most animals (including humans) are hyperopic because the short axial length places the retina in front of the focal plane. During postnatal development, an emmetropization mechanism uses cues related to refractive error to modulate the growth of the eye, moving the retina toward the focal plane. One possible cue may be longitudinal chromatic aberration (LCA), to signal if eyes are getting too long (long [red] wavelengths in better focus than short [blue]) or too short (short wavelengths in better focus)...
December 12, 2016: Experimental Eye Research
Z D Xiong, J Ke, G Z Zhao, Q H Lin, X M Yang, Y H Xiao
Objective: To compare dental and skeletal changes after rapid maxillary expansion in patients with different bone ages. Methods: Thirty-seven patients in different growth period were divided into three groups according to cervical vertebral maturation (CVM). There were 13 patients in the growth acceleration group, 13 patients in growth peak group, and 11 patients in growth deceleration group. Cone-beam computed tomography (CBCT) images were segmented and reconstructed using Mimics image processing software to assess the change of palatal morphology before and after treatment...
December 9, 2016: Zhonghua Kou Qiang Yi Xue za Zhi, Zhonghua Kouqiang Yixue Zazhi, Chinese Journal of Stomatology
Lucie Valek, Annett Häussler, Stefan Dröse, Philipp Eaton, Katrin Schröder, Irmgard Tegeder
Cyclic GMP-dependent protein kinase 1 (PKG1) mediates presynaptic nociceptive long-term potentiation (LTP) in the spinal cord and contributes to inflammatory pain in rodents but the present study revealed opposite effects in the context of neuropathic pain. We used a set of loss-of-function models for in vivo and in vitro studies to address this controversy: peripheral neuron specific deletion (SNS-PKG1(-/-)), inducible deletion in subsets of neurons (SLICK-PKG1(-/-)) and redox-dead PKG1 mutants. In contrast to inflammatory pain, SNS-PKG1(-/-) mice developed stronger neuropathic hyperalgesia associated with an impairment of nerve regeneration, suggesting specific repair functions of PKG1...
December 7, 2016: Redox Biology
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
Monichan Phay, Hak Hee Kim, Soonmoon Yoo
Small non-coding RNAs (sncRNAs) have been shown to play pivotal roles in spatiotemporal-specific gene regulation that is linked to many different biological functions. PIWI-interacting RNAs (piRNAs), typically 25-34-nucleotide long, are originally identified and thought to be restricted in germline cells. However, recent studies suggest that piRNAs associate with neuronal PIWI proteins, contributing to neuronal development and function. Here, we identify a cohort of piRNA-like sncRNAs (piLRNAs) in rat sciatic nerve axoplasm and directly contrast temporal changes of piLRNA levels in the nerve following injury, as compared with those in an uninjured nerve using deep sequencing...
December 13, 2016: Molecular Neurobiology
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