211 research outputs found
The Hidden Treasure in Apical Papilla: The Potential Role in Pulp/Dentin Regeneration and BioRoot Engineering
Some clinical case reports have shown that immature permanent teeth with periradicular periodontitis or abscess can undergo apexogenesis after conservative endodontic treatment. A call for a paradigm shift and new protocol for the clinical management of these cases has been brought to attention. Concomitantly, a new population of mesenchymal stem cells residing in the apical papilla of permanent immature teeth recently has been discovered and was termed stem cells from the apical papilla (SCAP). These stem cells appear to be the source of odontoblasts that are responsible for the formation of root dentin. Conservation of these stem cells when treating immature teeth may allow continuous formation of the root to completion. This article reviews current findings on the isolation and characterization of these stem cells. The potential role of these stem cells in the following respects will be discussed: (1) their contribution in continued root maturation in endodontically treated immature teeth with periradicular periodontitis or abscess and (2) their potential utilization for pulp/dentin regeneration and bioroot engineering
Machine-Assisted Map Editing
Mapping road networks today is labor-intensive. As a result, road maps have
poor coverage outside urban centers in many countries. Systems to automatically
infer road network graphs from aerial imagery and GPS trajectories have been
proposed to improve coverage of road maps. However, because of high error
rates, these systems have not been adopted by mapping communities. We propose
machine-assisted map editing, where automatic map inference is integrated into
existing, human-centric map editing workflows. To realize this, we build
Machine-Assisted iD (MAiD), where we extend the web-based OpenStreetMap editor,
iD, with machine-assistance functionality. We complement MAiD with a novel
approach for inferring road topology from aerial imagery that combines the
speed of prior segmentation approaches with the accuracy of prior iterative
graph construction methods. We design MAiD to tackle the addition of major,
arterial roads in regions where existing maps have poor coverage, and the
incremental improvement of coverage in regions where major roads are already
mapped. We conduct two user studies and find that, when participants are given
a fixed time to map roads, they are able to add as much as 3.5x more roads with
MAiD
Relationship between the morphology of A-1 segment of anterior cerebral artery and anterior communicating artery aneurysms
Background: The anterior communicating artery (ACoA) is one of the most frequent sites for cerebral aneurysm. The peculiar directions of projection of aneurysms offer great challenges to clinical treatment. Objetives: To establish the relationship between morphology of A-1 segment of anterior cerebral artery (ACA) and aneurismal projection. Methods: Randomly selected digital subtraction angiography data of 264 anterior communicating artery aneurysms (ACoAA) cases and 296 cases of other cerebral vascular diseases in the same period were retrospectively analyzed. Results: Among 264 ACoAA patients, the morphology of A-1 segment showed type â… a in 158 sides, type â… b in 11, type â…¡a in 35, type â…¡b in 87, type â…¢ in 171 and absence in 66. The morphology of A-1 segment in 296 patients with other cerebral vascular diseases displayed type â… a in 195 sides, type â… b in 20, type â…¡a in 47, type â…¡ b in 74, type â…¢ in 217 and absence in 39. The non-visualization of A-1 segment in the group of ACoAA occurred more than in the control group (χ2=11.482, p=0.001). The classifications of ACoAAs in 264 patients were confirmed as anterior-superior type in 121 cases, anterior-inferior type in 105, complicated type in 16, posterior-inferior type in 12 and posterior-superior type in 10. The correlation between morphology of A-1 segment of ACA and classifications of ACoAA was significant (p=0.000; C=0.619, p=0.000). The direction of ACoAA was downward when the A-1 segment of ACA was Type â… a or Type â…¡a, and was upward when it was Type â… b or Type â…¡b,and was upward or downward or complicated when it was Type â…¢. Conclusion: The relationship between morphology of A-1 segment of ACA and classification of ACoAA is clarified in the present study, which is helpful to surgical treatment.Keywords: anterior cerebral artery; morphology of A-1 segment; projection of anterior communicating artery aneurysmAfrican Health sciences Vol 14 No. 1 March 201
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Replication stress affects the fidelity of nucleosome-mediated epigenetic inheritance
The fidelity of epigenetic inheritance or, the precision by which epigenetic information is passed along, is an essential parameter for measuring the effectiveness of the process. How the precision of the process is achieved or modulated, however, remains largely elusive. We have performed quantitative measurement of epigenetic fidelity, using position effect variegation (PEV) in Schizosaccharomyces pombe as readout, to explore whether replication perturbation affects nucleosome-mediated epigenetic inheritance. We show that replication stresses, due to either hydroxyurea treatment or various forms of genetic lesions of the replication machinery, reduce the inheritance accuracy of CENP-A/Cnp1 nucleosome positioning within centromere. Mechanistically, we demonstrate that excessive formation of single-stranded DNA, a common molecular abnormality under these conditions, might have correlation with the reduction in fidelity of centromeric chromatin duplication. Furthermore, we show that replication stress broadly changes chromatin structure at various loci in the genome, such as telomere heterochromatin expanding and mating type locus heterochromatin spreading out of the boundaries. Interestingly, the levels of inheritable expanding at sub-telomeric heterochromatin regions are highly variable among independent cell populations. Finally, we show that HU treatment of the multi-cellular organisms C. elegans and D. melanogaster affects epigenetically programmed development and PEV, illustrating the evolutionary conservation of the phenomenon. Replication stress, in addition to its demonstrated role in genetic instability, promotes variable epigenetic instability throughout the epigenome
RoadTagger: Robust Road Attribute Inference with Graph Neural Networks
Inferring road attributes such as lane count and road type from satellite
imagery is challenging. Often, due to the occlusion in satellite imagery and
the spatial correlation of road attributes, a road attribute at one position on
a road may only be apparent when considering far-away segments of the road.
Thus, to robustly infer road attributes, the model must integrate scattered
information and capture the spatial correlation of features along roads.
Existing solutions that rely on image classifiers fail to capture this
correlation, resulting in poor accuracy. We find this failure is caused by a
fundamental limitation -- the limited effective receptive field of image
classifiers. To overcome this limitation, we propose RoadTagger, an end-to-end
architecture which combines both Convolutional Neural Networks (CNNs) and Graph
Neural Networks (GNNs) to infer road attributes. The usage of graph neural
networks allows information propagation on the road network graph and
eliminates the receptive field limitation of image classifiers. We evaluate
RoadTagger on both a large real-world dataset covering 688 km^2 area in 20 U.S.
cities and a synthesized micro-dataset. In the evaluation, RoadTagger improves
inference accuracy over the CNN image classifier based approaches. RoadTagger
also demonstrates strong robustness against different disruptions in the
satellite imagery and the ability to learn complicated inductive rules for
aggregating scattered information along the road network
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