4,510 research outputs found

    Three-dimensional reconstructions of intrahepatic bile duct tubulogenesis in human liver

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    <p>Abstract</p> <p>Background</p> <p>During liver development, intrahepatic bile ducts are thought to arise by a unique asymmetric mode of cholangiocyte tubulogenesis characterized by a series of remodeling stages. Moreover, in liver diseases, cells lining the Canals of Hering can proliferate and generate new hepatic tissue. The aim of this study was to develop protocols for three-dimensional visualization of protein expression, hepatic portal structures and human hepatic cholangiocyte tubulogenesis.</p> <p>Results</p> <p>Protocols were developed to digitally visualize portal vessel branching and protein expression of hepatic cell lineage and extracellular matrix deposition markers in three dimensions. Samples from human prenatal livers ranging from 7 weeks + 2 days to 15½ weeks post conception as well as adult normal and acetaminophen intoxicated liver were used. The markers included cytokeratins (CK) 7 and 19, the epithelial cell adhesion molecule (EpCAM), hepatocyte paraffin 1 (HepPar1), sex determining region Y (SRY)-box 9 (SOX9), laminin, nestin, and aquaporin 1 (AQP1).</p> <p>Digital three-dimensional reconstructions using CK19 as a single marker protein disclosed a fine network of CK19 positive cells in the biliary tree in normal liver and in the extensive ductular reactions originating from intrahepatic bile ducts and branching into the parenchyma of the acetaminophen intoxicated liver. In the developing human liver, three-dimensional reconstructions using multiple marker proteins confirmed that the human intrahepatic biliary tree forms through several developmental stages involving an initial transition of primitive hepatocytes into cholangiocytes shaping the ductal plate followed by a process of maturation and remodeling where the intrahepatic biliary tree develops through an asymmetrical form of cholangiocyte tubulogenesis.</p> <p>Conclusions</p> <p>The developed protocols provide a novel and sophisticated three-dimensional visualization of vessels and protein expression in human liver during development and disease.</p

    CAD-CAM workflow for the fabrication of bioscaffolds and porous auricular constructs with polycaprolactone using Ultimaker 2+

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    In recent years, the application of three-dimensional fabrication to fabricate customized porous scaffolds for cell culture has received much attention from the field of tissue engineering and plastic surgery. In this study, we applied a more publicly accessible 3D printer, Ultimaker 2+ with biodegradable polymer-polycaprolactone (PCL) to fabricate both three-dimensional bioscaffolds and auricular constructs (both solid and porous) prepared to fill the gap as potential solutions for both cartilage defects and microtia respectively by managing of the CAD-CAM workflow. As an overview, the modified CAD-CAM workflow was regarded as the uniform preparation fabricating types of scaffolds to identify the general printability of PCL with Ultimaker 2+. For bioscaffolds, limit test was performed on original scaffold, the resolution for printing scaffolds by PCL was identified as 600 microns by applying method of uniform scaling and limit approaching. For customized auricular constructs, we extract the model from MRI/CT scan and use its mirror image for the general shape of model building in a relatively customized way to fabricate solid auricular constructs. Boolean operation was then applied for fabricating the inner porous microstructure to fabricate porous auricular constructs. As there were no significant differences among three groups of filaments regarding the respective dimensions for both bioscaffolds (n=9 for each group: PCL, PLA and ABS) and customized auricular constructs(n=5 for both solid auricular constructs and porous auricular constructs) indicated by the P value(P>0.05) from ANOVA, The printing compatibility of PCL regarding each specific domain of scaffolds were identified. In Conclusion, our study had indicated a consistent CAD-CAM workflow for Ultimaker 2+ with PCL to fabricate three-dimensional bioscaffolds, solid auricular constructs and porous auricular constructs which could be potentially applied to fill the gap of cartilage engineering and microtia reconstruction through in-vitro cell culture, surgical simulation and in-situ cell culture respectively

    Laminar Cortical Dynamics of Visual Form and Motion Interactions During Coherent Object Motion Perception

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    How do visual form and motion processes cooperate to compute object motion when each process separately is insufficient? A 3D FORMOTION model specifies how 3D boundary representations, which separate figures from backgrounds within cortical area V2, capture motion signals at the appropriate depths in MT; how motion signals in MT disambiguate boundaries in V2 via MT-to-Vl-to-V2 feedback; how sparse feature tracking signals are amplified; and how a spatially anisotropic motion grouping process propagates across perceptual space via MT-MST feedback to integrate feature-tracking and ambiguous motion signals to determine a global object motion percept. Simulated data include: the degree of motion coherence of rotating shapes observed through apertures, the coherent vs. element motion percepts separated in depth during the chopsticks illusion, and the rigid vs. non-rigid appearance of rotating ellipses.Air Force Office of Scientific Research (F49620-01-1-0397); National Geospatial-Intelligence Agency (NMA201-01-1-2016); National Science Foundation (BCS-02-35398, SBE-0354378); Office of Naval Research (N00014-95-1-0409, N00014-01-1-0624

    09251 Abstracts Collection -- Scientific Visualization

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    From 06-14-2009 to 06-19-2009, the Dagstuhl Seminar 09251 ``Scientific Visualization \u27\u27 was held in Schloss Dagstuhl~--~Leibniz Center for Informatics. During the seminar, over 50 international participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general

    Investigating the roles of Hes and Sox genes during embryogenesis of the spider Parasteatoda tepidariorum

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    One goal of evolutionary developmental biology is to understand the mechanisms that underlie the regulation and evolution of embryogenesis among different species. One approach to answer these questions is to study and compare the expression and function of “toolbox” genes in different lineages. Members of two conserved gene families, Hes and Sox, are involved in both segmentation and neurogenesis in different metazoans. Genes such as hairy and Dichaete are involved in the segmentation cascade in Drosophila melanogaster, whereas deadpan and Sox21B acts in the regulation of the neurogenic precursors in the same species. To broaden our understanding of the evolution and function of these genes, for this project, I studied them in the commonhouse spider P. tepidariorum: an emergent organism to studies in comparative embryology and genetics, and which has experienced a whole genome duplication in its evolutionary history. I characterized the expression of four Hes-like genes and fifteen Sox genes in this species. Briefly, hairy and Sox21B-1 are expressed in prosoma as well as in the posterior segment addition zone and forming segments. deadpan, hey, side, SoxNeuro, Sox C-1 and Sox D-2 are expressed in the central nervous system, and Sox E-2 and Sox F-2 in the mechanoceptors of the walking limbs and peripheral nervous system. I also carried out functional analysis of Sox21b-1 and demonstrated its involvement in the gene regulatory network that is responsible for the posterior segment addition in the spider, as well as a striking relation with secondary layers formation. Finally, I generated new resources to help develop new functional tools in P. tepidariorum in order to make genomic manipulations in this species, as well as to improve techniques such as live imaging and in situ hybridization. Taken together my research embraced different aspects of the spider embryogenesis and prove that the chelicerates are emerging research systems to the study of evolutionary developmental biology

    Mid-level Priming by Completion vs. Mosaic Solutions

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    We report two experiments on the role of mid-level processes in image segmentation and completion. In the primed matching task of Experiment 1, a cue!prime sequence was presented before the imperative stimulus consisting of target shapes with positive versus negative contour curvature polarity and one versus two axes of mirror symmetry. Priming shapes were included in two composite occlusion displays with the same T-junction information and different geometric features supporting a distinct balance between completion and mosaic solutions. A cue, either congruent or incongruent with targets, preceded the presentation of the composite priming display. Matching performance was affected by primes in the expected direction, while cue congruency participated only in a marginally significant three-way interaction, and prime duration had no effect. In Experiment 2, the cue!prime sequence was replaced by a fixation cross to control for the priming effect obtained in Experiment 1. The study confirmed that contour connectability and curvature polarity are effective structural factors capable of competing with symmetry in mid-level image segmentation and completion processes
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