Floor Plate Research Articles

Human iPS cell-derived dopaminergic neurons function in a primate Parkinson's disease model.

Induced pluripotent stem cells (iPS cells) are a promising source for a cell-based therapy to treat Parkinson's disease (PD), in which midbrain dopaminergic neurons progressively degenerate. However, long-term analysis of human iPS cell-derived dopaminergic neurons in primate PD models has never been performed to our knowledge. Here we show that human iPS cell-derived dopaminergic progenitor cells survived and functioned as midbrain dopaminergic neurons in a primate model of PD (Macaca fascicularis) treated with the neurotoxin MPTP. Score-based and video-recording analyses revealed an increase in spontaneous movement of the monkeys after transplantation. Histological studies showed that the mature dopaminergic neurons extended dense neurites into the host striatum; this effect was consistent regardless of whether the cells were derived from patients with PD or from healthy individuals. Cells sorted by the floor plate marker CORIN did not form any tumours in the brains for at least two years. Finally, magnetic resonance imaging and positron emission tomography were used to monitor the survival, expansion and function of the grafted cells as well as the immune response in the host brain. Thus, this preclinical study using a primate model indicates that human iPS cell-derived dopaminergic progenitors are clinically applicable for the treatment of patients with PD.

A new model for netrin1 in commissural axon guidance.

Now-classic experiments characterized netrin1 as a major player in commissural axon guidance in the spinal cord. The data suggest a chemotactic model in which netrin1 expression in the floor plate forms a concentration gradient that attracts commissural axons. New research published independently in Neuron and in Nature tests this model by deleting netrin1 specifically in the floor plate. Surprisingly, these conditional mutant mice have no overt commissure defects. The authors report that netrin1 decorates the pial surface of the spinal cord and hindbrain, likely deposited by radial processes of progenitor cells in the ventricular zone. They find that deletion of the cue exclusively in the ventricular zone causes commissural axons to take aberrant trajectories, suggesting a short range, haptotactic guidance mechanism as opposed to chemotaxis. This minireview aims to summarize the classic and the new findings and offer some interpretations of the data.

Expansion of human midbrain floor plate progenitors from induced pluripotent stem cells increases dopaminergic neuron differentiation potential

Human induced pluripotent stem cells (hiPSCs) are invaluable to study developmental processes and disease mechanisms particularly in the brain. hiPSCs can be differentiated into mature and functional dopaminergic (DA) neurons. Having robust protocols for the generation of differentiated DA neurons from pluripotent cells is a prerequisite for the use of hiPSCs to study disease mechanisms, for drug discovery, and eventually for cell replacement therapy. Here, we describe a protocol for generating and expanding large numbers of homogeneous midbrain floor plate progenitors (mFPPs) that retain efficient DA neurogenic potential over multiple passages and can be cryobanked. We demonstrate that expanded mFPPs have increased DA neuron potential and differentiate more efficiently and rapidly than progenitors generated by standard protocols. In addition, this novel method results in increased numbers of DA neurons that in vitro show characteristic electrophysiological properties of nigrostriatal DA neurons, produce high levels of dopamine, and integrate into host mice when grafted in vivo. Thus, we describe a robust method for producing human mesencephalic DA neurons from hiPSCs.

Stability Analysis of Cube Tanks’ Ceiling and Floor Plates Composed of FGMs when Subjected to Uniform Compression Perpendicular to the Mid-Plane

Stability Analysis of Cube Tanks’ Ceiling and Floor Plates Composed of FGMs when Subjected to Uniform Compression Perpendicular to the Mid-Plane

Direction of commissural axon projections in different regions of the spinal cord during chicken embryonic development

Few researchers have investigated the direction of commissural axon projections on the contralateral side of the vertebrate embryonic spinal cord, especially for comparison between its different regions. In this study, pCAGGS-GFP plasmid expression was limited to different regions of the chicken embryonic spinal cord (cervical, anterior limb, anterior thorax, posterior thorax and posterior limb) at E3 using in ovo electroporation with modified electrodes and optimal electroporation conditions. Then open-book technique was performed at E6 to analyze the direction of axon projections in different spinal cord regions. The results show that in the five investigated regions, most axons projected rostrally after crossing the floor plate while a minority projected caudally. And there was a significant difference between the rostral and caudal projection quantities (P<0.01). The ratio of rostral and caudal projections was significantly different between the five investigated regions (P<0.05), except between the cervical region and the anterior limb (P>0.05). The projections were most likely to be rostral for the posterior limb followed by the posterior thorax, cervical region, anterior limb and anterior thorax. Our data for the direction of the commissural axon projections will be helpful in the future analyses of axon projection mechanisms and spinal cord-brain circuit formation.

Changes in work accuracy in a noisy environment : A case of work accuracy in the marine engine room environment

It is a requirement that the noise level in the engine rooms of modern ships meet the International Maritime Organization (IMO) noise level code criteria. This standard comes as it had been revealed that, in noisy environments, ship engineers are uncomfortable and lack concentration, and as a result might experience a reduction in work accuracy. In a noisy environment, it has been found that engineers not only feel fatigued but also work with less precision. These facts have been empirically demonstrated. In the laboratory, a noisy environment was reconstructed by playing the machine operating sound, recorded in a ship engine room, and laying down metal floor plates similar to those found in a ship engine room. Speakers were installed under the metal floor plates, and the recorded machine operating sounds were played back from the speakers during the experiments. In the experiments, the participants were asked to perform work tasks in the noisy environment. The participants’ biological responses were measured during the experiment. The output from speakers during the experiment was measured by a precision sound level meter at a height corresponding to the ear level of the participant. In this study, we measured biological responses, such as heartbeat and brain waves (alpha band wave, beta band wave, etc.), as an evaluation index. From the biological responses, we estimated the participants’ mental workload in the noisy environment.

Nogo-B is the major form of Nogo at the floor plate and likely mediates crossing of commissural axons in the mouse spinal cord.

Using Nogo antibodies with defined binding specificity, Nogo-B, but not Nogo-A, was localized on radial glia in the floor plate of mouse embryos. The presence of Nogo-B was confirmed in Nogo-A knockout mice. In explant cultures of embryonic day (E) 11 and E12 spinal cord, blocking of NgR function with antagonist peptide NEP1-40 reduced the crossing of newly arrived commissural axons, resulting in an accumulation of growth cones in the floor plate. Analysis of growth cone morphology demonstrated an increase in size of growth cones in the floor plate after peptide treatment, which was not detected in axons growing toward the midline. In knockout embryos, midline crossing was not affected by absence of Nogo-A. In co-culture experiments using collagen gel, floor plate showed a strong inhibitory effect on the extension of post-commissural neurites from the spinal cord. This effect was abolished by NEP1-40, and was observed neither in pre-commissural neurites, nor in post-commissural neurites grown with floor plate derived from Nogo-A knockout embryo. Furthermore, western blot analysis of conditioned medium from floor plates showed a truncated form of Nogo with molecular weight of 37 kDa, which could mediate the diffusible effect to axon growth. We conclude that Nogo-B is expressed in the floor plate of mouse embryo, which probably mediates axon crossing in the spinal cord by repelling axons out of the midline when they start upregulate NgR. Nogo acts on axon growth not only through a contact-mediated mechanism, but also through a diffusible mechanism.

A critical review of “travelling fire” scenarios for performance-based structural engineering

Many studies of the thermal and structural behaviour for large compartments in fire carried out over the past two decades show that fires in such compartments have a great deal of non-uniformity (e.g. Stern-Gottfried et al. [1]), unlike the homogeneous compartment temperature assumption in the current fire safety engineering practice. Furthermore, some large compartment fires may burn locally and tend to move across entire floor plates over a period of time. This kind of fire scenario is beginning to be idealized as travelling fires in the context of performance-based structural and fire safety engineering.This paper presents a literature review of the travelling fire research topic and its state of the art, including both the experimental and theoretical work for the past twenty years. It is found that the main obstacle of developing the travelling fire knowledge is the lack of understanding of the physical mechanisms behind this kind of fire scenario, which requires more reasonable large scale travelling fire experiments to be set up and carried out. The demonstration of the development of a new travelling fire framework is also presented in this paper, to show how current available experimental data hinder the analytical model development, and the urgent need that the new travelling fire experiments should be conducted.

New insights concerning homology of the oral region and ambulacral system plating of pentaradial echinoderms

AbstractUniversal elemental homology (UEH) underpins recent understanding of peristomial and ambulacral elemental homology of pentaradiate echinoderms by providing a uniform set of terminology to construct phylogenetic characters. Variation in the expression of these elements provides evidence for phylogenetic relationships. Two nonhomologous sets of plates border the peristome and are associated with two nonhomologous sets of floor plates forming the ambulacral food groove. Some edrioasteroid-grade and eocrinoid-grade echinoderms have ambulacral systems formed from oral frame plates and adradial floor plates, whereas most blastozoans and crinoids bear oral plates and abradial floor plates. These plates are expressed in a variety of ways among echinoderms, but nearly all can be reconciled with the underlying model. Arguments against UEH are methodologically flawed and confuse many terms and interpretations.

The Robo3 receptor, a key player in the development, evolution, and function of commissural systems.

Roundabout receptors are known to mediate Slit-dependent repulsive signaling. However in vertebrates, mounting evidence suggest that Robo3 is an unconventional Robo receptor regarding both its expression and function. From its initial description, the Robo3 receptor has been tightly associated with the development of specific axons, called commissural, that connect both sides of the nervous system. Many studies using transgenic mouse models showed that Robo3 expression is mandatory for commissural axon guidance to the floor plate. Moreover, mutations in human ROBO3 are responsible for a rare neurological disease in which patients also display midline crossing defects. Robo3 was initially thought to counteract Slit/Robo repulsion. However, recent studies support an alternative model where Robo3 potentiates midline attraction. These studies support a complex, central and multifaceted role of Robo3 in controlling the development of commissural circuits. Furthermore, the analysis of Robo3 evolution in vertebrates points out the specificity of this receptor in the mammalian lineage, suggesting mechanistic and functional divergence of Robo3 in mammals compared to a more traditional function in other vertebrates. Here, we review the current knowledge about Robo3 function, from the regulation of its expression to signaling. We also present evidence for a high variability of Robo3 splice variants in vertebrates. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 876-890, 2017.

Art by Design

The University of Iowa’s Visual Arts Building opened last fall on a campus that is still recovering from flooding in 2008 that caused nearly $800 million in damage. The structure houses the university’s studio arts education program and is a physical manifestation of the theories that will be taught within its walls. Boasting offset floor plates and perimeter cutouts, the building itself is a piece of art composed of both volumes and voids.

Studying Gene Expression in Whole Embryos by in situ Hybridization: A Peer-to-Peer Laboratory Guide

The extracellular matrix (ECM) plays an important role in cell to cell signaling pathways. Our goal is to provide a full laboratory guide for students to study gene expression in zebrafish embryos by in situ hybridization. Prior to our study, the laboratory had observed disorganized and shortened cilia in cells that are important for cell signaling in the pronephric duct and neural tube floor plate of the zebrafish embryo. Ciliogenesis depends on a master transcriptional regulator, foxj1a, whose mRNA expression can be monitored through in situ hybridization and microscopic imaging. Knockdown morpholino-injected, control mismatched morpholino-injected, and uninjected embryos were fixed to determine if foxj1a transcription is qualitatively affected by ECM gene knockdown. Our results showed that the knockdown embryos portrayed an inconsistent foxj1a signal strength along the length of the pronephric duct, when compared to analysis of control mismatched and wild-type uninjected embryos. We created this manuscript for other students to observe how ECM gene knockdown can affect foxj1a mRNA expression, but also to give them a guide to the tools they would need to explore their own genes of interest, in zebrafish or in many other organisms and tissues.

Structural response of a steel-frame building to horizontal and vertical travelling fires in multiple floors

During previous fire events such as the World Trade Centre Towers (WTC) 1, 2 & 7 in New York (2001), the Windsor Tower in Madrid (2005), and the Plasco building in Iran (2017), flames were observed to travel horizontally across the floor plate and vertically to different floors. Such fires are not considered as part of the traditional prescriptive structural design for fire. Recently, the Travelling Fires Methodology (TFM) has been developed to account for such horizontally travelling nature of fires. A dozen of studies have investigated the structural response of steel, concrete, and composite structures to a single-floor travelling fire. 5 out of 6 of the vertically travelling fire studies have been limited to the structures with a long span composite truss system as in the WTC Towers. The aim of this work is to investigate the response of a substantially different structural system, i.e. a generic multi-storey steel frame, subjected to travelling fires in multiple floors, and varying the number of fire floors, including horizontal and vertical fire spread. A two-dimensional 10-storey 5-bay steel frame is modelled in the finite element software LS-DYNA. The number of multiple fire floors is varied between 1 and 10, and for each of these scenarios, 5 different fire types are investigated. They include four travelling fire scenarios and the standard fire. In total, 51 fire simulations are considered. The development of deflections, axial forces, bending moments and frame utilization are analysed. Results show that the largest stresses develop in the fire floors adjacent to cool floors, and their behaviour is independent of the number of fire floors. Results indicate that both the fire type and the number of fire floors have a significant effect on the failure time (i.e. exceeded element load carrying capacity) and the type of collapse mechanism. In the cases with a low number of fire floors (1–3) failure is dominated by the loss of material strength, while in the cases with larger number of fire floors (5–10) failure is dominated by thermal expansion. Collapse is mainly initiated by the pull-in of external columns (1–3-floor fires; 1–9-floor fires for 2.5% TFM) or swaying of the frame to the side of fire origin (5–10-floor fires). This study has assessed a different structural form compared to previous literature under an extensive range of multiple floor travelling fire scenarios. We find that although vertically travelling fires result in larger beam axial forces and initial deflections, simultaneous travelling fires result in shorter failure times and represent a more onerous scenario for the steel frame investigated.

Floor-plate-derived netrin-1 is dispensable for commissural axon guidance.

Netrin-1 is an evolutionarily conserved secreted extracellular matrix protein discovered using genetic and biochemical screens for its role in axon guidance at the central nervous system (CNS) midline1,2. Netrin-1 is expressed by cells localized at CNS midline, such as the floor plate in vertebrate embryos1,3. Growth cone turning assays and 3D gel diffusion assays showed that netrin-1 can attract commissural axons2,4–6. Loss-of-function experiments further demonstrated that commissural axon extension to the midline is severely impaired in absence of netrin-13,7–9. Together these data support a model in which commissural axons are attracted by a netrin-1 gradient diffusing from the midline. Here, we selectively ablated netrin-1 expression in floor plate cells using a Netrin-1 conditional mouse line. We found that hindbrain and spinal cord commissural axons develop normally in absence of floor plate-derived netrin-1. Furthermore, we show that netrin-1 is highly expressed by cells in the ventricular zone with the potential to release it at the pial surface where it binds to commissural axons. Importantly, netrin-1 deletion from the ventricular zone phenocopies commissural axon guidance defects previously described in Netrin-1 knockout mice. These results show that the classical textbook view that attraction of commissural axons is mediated by a gradient of floor plate-derived netrin-1 is inaccurate and that netrin-1 primarily acts locally by promoting growth cone adhesion.

Netrin1 Produced by Neural Progenitors, Not Floor Plate Cells, Is Required for Axon Guidance in the Spinal Cord

Netrin1 has been proposed to act from the floor plate (FP) as a long-range diffusible chemoattractant for commissural axons in the embryonic spinal cord. However, netrin1 mRNA and protein are also present in neural progenitors within the ventricular zone (VZ), raising the question of which source of netrin1 promotes ventrally directed axon growth. Here, we use genetic approaches in mice to selectively remove netrin from different regions of the spinal cord. Our analyses show that the FP is not the source of netrin1 directing axons to the ventral midline, while local VZ-supplied netrin1 is required for this step. Furthermore, rather than being present in a gradient, netrin1 protein accumulates on the pial surface adjacent tothe path of commissural axon extension. Thus, netrin1 does not act as a long-range secreted chemoattractant for commissural spinal axons but instead promotes ventrally directed axon outgrowth by haptotaxis, i.e., directed growth along an adhesive surface.

Spop regulates Gli3 activity and Shh signaling in dorsoventral patterning of the mouse spinal cord

Sonic Hedgehog (Shh) signaling regulates the patterning of ventral spinal cord through the effector Gli family of transcription factors. Previous in vitro studies showed that an E3 ubiquitin ligase containing Speckle-type POZ protein (Spop) targets Gli2 and Gli3 for ubiquitination and degradation, but the role of Spop in Shh signaling and mammalian spinal cord patterning remains unknown. Here, we show that loss of Spop does not alter spinal cord patterning, but it suppresses the loss of floor plate and V3 interneuron phenotype of Gli2 mutants, suggesting a negative role of Spop in Gli3 activator activity, Shh signaling and the specification of ventral cell fates in the spinal cord. This correlates with a moderate but significant increase in the level of Gli3 protein in the Spop mutant spinal cords. Furthermore, loss of Spop restores the maximal Shh pathway activation and ventral cell fate specification in the Gli1;Sufu double mutant spinal cord. Finally, we show that loss of Spop-like does not change the spinal cord patterning in either wild type or Spop mutants, suggesting that it does not compensate for the loss of Spop in Shh signaling and spinal cord patterning. Therefore, our results demonstrate a negative role of Spop in the level and activity of Gli3, Shh signaling and ventral spinal cord patterning.

Analisa Perhitungan Perencanaan Gedung Perkantoran STT Pagar Alam Dengan Metode Manual Dan Staad Pro 2007

Office building planning Pagar Alam Technology College is one of the efforts to improve the function and role of office buildings. The selection of structural materials to be used for certain buildings is influenced by the height and span of the structure, availability of materials in the market, foundation conditions, local building regulations and architectural considerations. The frame building system consists of horizontal elements (beams), vertical (columns) and floor plates. Tall building frames can be viewed geometrically as a sum of portal frames. In this study, the results of the analysis showed that the diameter of the floor beam 30 x 15 = 8 D 14, roof diameter 30 x 15 = 4 D 12, column diameter 30 X 30 = 6 D 14, floor plate Ø 10 sengkang 100, roof plate Ø 10 sengkang 100, ladder Ø 100 sengkang 100. The analysis uses the 2007 pro station which produces the dimensions of the roof beam 20 x 30, beam dimensions 20 x 40, column 30 x 30 number of reinforcement 8 D 12

Analisa Struktur Atas (Upper Structure) Jembatan Kaburejo Kota Pagar Alam

One means of transportation is a bridge that connects an area due to obstacles or road divides. There are many bridges in the City of Pagar Alam, one of which is in the Kaburejo area, the bridge in this area is less feasible for vehicles because it has a smaller bridge span than the highway. The purpose of this study is to do an upper structure re-design with a 6 m wide bridge and a 15 m long bridge span made with reinforced concrete construction that has a reinforced longitudinal beam which is an integral part of the vehicle floor so that it can meet the maximum traffic capacity. Bridge planning analysis is carried out on the bridge structure which includes the backrest, sidewalk floor, floor plate and main beam.

Interaction of buckling modes in railway plate girder steel bridges

This paper investigates, for the first time, the behaviour and design of railway double track open timber floor plate girder deck steel bridges under combined buckling modes including web distortional buckling. A 3-D finite element model has been developed for the railway bridges, which accounted for the bridge geometries, initial geometric imperfections, material nonlinearities of the bridge components, bridge boundary conditions, interactions among bridge components and bridge bracing systems. Most of the aforementioned parameters are not incorporated in current design codes of railway bridges, which are credited to this study. The simply supported bridges investigated had a span of 30m, a width of 7.2m and a depth of 3.12m. The bridge components comprising main plate girders, stringers, cross girders, connections, bracing members, stiffeners, bearings, and field splices were designed following the design rules specified in the European Code for steel bridges. The live load acting on the bridge was Load Model 71, which represents the static effect of vertical loading due to normal rail traffic as specified in the European Code. The finite element model of the double track bridge was developed depending on additional finite element models, developed by the author, for small and full-scale plate girder steel bridge tests previously reported in the literature. Ultimate loads, load-mid-span deflection relationships, failure modes, stress contours of the double track bridge as well as of the small and full-scale tests were predicted from the finite element analysis and compared well against test results. Parametric studies were performed on the railway bridges highlighting the effects on the structural behaviour and ultimate loads carried by the bridges owing to the change in the bridge geometries, slenderness and steel strength. The paper presents a complete piece of work regarding the finite element analysis and design of railway steel bridges, which can be used for further parametric studies, finite element analyses and investigations of the bridges under different loading and boundary conditions. The parametric study has shown that the presence of web distortional buckling causes a considerable decrease in the ultimate load of the steel bridges. It is also shown that the use of high strength steel offers a considerable increase in the ultimate loads of less slender steel bridges. The study has also shown that the design rules, loading and recommendations specified in the European Code provide accurate and conservative estimations for the design of railway steel bridges, except for the bridges failing mainly by web distortional buckling.

Testing for homologies in the axial skeleton of primitive echinoderms

AbstractThe extraxial axial theory is used to investigate homology of ambulacral and oral plating because it predicts terminal branching and terminal addition of plates in the axial skeleton, although exceptions to the former may occur in some Paleozoic echinoderms. The variety of morphological designs and anomalous individuals also provide tests of plate homology. Homology of ambulacra is generally accepted, with the hydropore and/or single gonopore in Carpenter’s CD interray. In the 2-1-2 ambulacral pattern the unbranched ambulacrum is always in Carpenter’s A ray. All ambulacral morphology requires just three instructions: ‘grow,’ ‘branch,’ and ‘stop.’ The range of variation in echinoderms with fewer than five ambulacra implies that both the ‘branch’ and ‘stop’ instructions acted independently in all five rays. Numbers of ambulacra may or may not correlate with numbers of orals. Two basic patterns of ‘cystoid’ oral plating occur; with a single radial (circum-oral, CO) plate from each ambulacrum plus a sixth in the CD interray, and with all six interradial peri-oral (PO) plates, with two in the CD interambulacrum. Five ‘orals’ may involve loss of PO3 or PO6. Erect ambulacral structures are lost first in taphonomy and so poorly known. All ambulacral skeletal elements bear the same topological relationship to ambulacral soft tissues. Where branched ambulacra occur, the trunk or flooring plates are often modified first brachiolars or pinnulars. Both brachioles and pinnules may arise from facets developed on one or two flooring plates. Terminal addition of plates, spacing of brachioles/pinnules, and lack of musculature to open cover plates all suggest that ‘cystoids’ had extensions of the water vascular system in their ambulacra.