68 research outputs found
Reinforcement of polystyrene using edge-styrene graphitic nanoplatelets
Edge-styrene graphitic nanoplatelets (StGnPs) were prepared by the in-situ mechanochemical reaction between graphite and styrene without additional chemical reaction (e.g. functionalization). The resultant StGnPs exhibited excellent properties including good dispersibility in organic solvents, to use an efficient reinforcing additive for polystyrene (PS) that is one of the most widely used plastics. StGnP/PS nanocomposites were prepared easily via a facile solution process method. Compared to pure PS, the StGnP/PS nano composites exhibited significantly enhanced mechanical properties (e.g., tensile strength, yield strength, Young's modulus, and tensile toughness) along with improved thermal stability. The StGnP/PS nanocomposites showed efficient load transfer from the PS matrix to the StGnPs because of the good dispersibility and compatibility of the StGnPs in the PS matrix. And also, the mechanochemical reaction showed that GnPs having remarkable compatibility of various polymers can be produced freely. (C) 2020 The Author(s). Published by Elsevier B.V
Abolished ketamine effects on the spontaneous excitatory postsynaptic current of medial prefrontal cortex neurons in GluN2D knockout mice
Abstract
Ketamine, a non-competitive antagonist of the N-methyl-d-aspartate receptor (NMDAR), generates a rapidly-acting antidepressant effect. It exerts psychomimetic effects, yet demands a further investigation of its mechanism. Previous research showed that ketamine did no longer promote hyperlocomotion in GluN2D knockout (KO) mice, which is a subunit of NMDAR. In the present study, we tested whether GluN2D-containing NMDARs participate in the physiological changes in the medial prefrontal cortex (mPFC) triggered by ketamine. Sub-anesthetic dose of ketamine (25mg/kg) elevated the frequency of spontaneous excitatory postsynaptic currents (sEPSC) in wild-type (WT) mice, but not in GluN2D KO mice, 1h after the injection. The amplitude of sEPSC and paired-pulse ratio (PPR) were unaltered by ketamine in both WT and GluN2D KO mice. These findings suggest that GluN2D-containing NMDARs might play a role in the ketamine-mediated changes in glutamatergic neurons in mPFC and, presumably, in ketamine-induced hyperlocomotion
PHF7 Modulates BRDT Stability and Histone-to-Protamine Exchange during Spermiogenesis
Chang Rok Kim, Taichi Noda, Hyunkyung Kim, Gibeom Kim, Seongwan Park, Yongwoo Na, Seiya Oura, Keisuke Shimada, Injin Bang, Jun-Yeong Ahn, Yong Ryoul Kim, Se Kyu Oh, Hee-Jung Choi, Jong-Seo Kim, Inkyung Jung, Ho Lee, Yuki Okada, Masahito Ikawa, Sung Hee Baek, PHF7 Modulates BRDT Stability and Histone-to-Protamine Exchange during Spermiogenesis, Cell Reports, Volume 32, Issue 4, 2020, 107950, ISSN 2211-1247, https://doi.org/10.1016/j.celrep.2020.107950
Spontaneous Oscillatory Rhythm in Retinal Activities of Two Retinal Degeneration (rd1 and rd10) Mice
Previously, we reported that besides retinal ganglion cell (RGC) spike, there is ~ 10 Hz oscillatory rhythmic activity in local field potential (LFP) in retinal degeneration model, rd1 mice. The more recently identified rd10 mice have a later onset and slower rate of photoreceptor degeneration than the rd1 mice, providing more therapeutic potential. In this study, before adapting rd10 mice as a new animal model for our electrical stimulation study, we investigated electrical characteristics of rd10 mice. From the raw waveform of recording using 8×8 microelectrode array (MEA) from in vitro-whole mount retina, RGC spikes and LFP were isolated by using different filter setting. Fourier transform was performed for detection of frequency of bursting RGC spikes and oscillatory field potential (OFP). In rd1 mice, ~10 Hz rhythmic burst of spontaneous RGC spikes is always phase-locked with the OFP and this phase-locking property is preserved regardless of postnatal ages. However, in rd10 mice, there is a strong phase-locking tendency between the spectral peak of bursting RGC spikes (~5 Hz) and the first peak of OFP (~5 Hz) across different age groups. But this phase-locking property is not robust as in rd1 retina, but maintains for a few seconds. Since rd1 and rd10 retina show phase-locking property at different frequency (~10 Hz vs. ~5 Hz), we expect different response patterns to electrical stimulus between rd1 and rd10 retina. Therefore, to extract optimal stimulation parameters in rd10 retina, first we might define selection criteria for responding rd10 ganglion cells to electrical stimulus
Porcine sapovirus Cowden strain enters LLC-PK cells via clathrin- and cholesterol-dependent endocytosis with the requirement of dynamin II.
Caliciviruses in the genus Sapovirus are a significant cause of viral gastroenteritis in humans and animals. However, the mechanism of their entry into cells is not well characterized. Here, we determined the entry mechanism of porcine sapovirus (PSaV) strain Cowden into permissive LLC-PK cells. The inhibition of clathrin-mediated endocytosis using chlorpromazine, siRNAs, and a dominant negative (DN) mutant blocked entry and infection of PSaV Cowden strain, confirming a role for clathrin-mediated internalization. Entry and infection were also inhibited by the cholesterol-sequestering drug methyl-β-cyclodextrin and was restored by the addition of soluble cholesterol, indicating that cholesterol also contributes to entry and infection of this strain. Furthermore, the inhibition of dynamin GTPase activity by dynasore, siRNA depletion of dynamin II, or overexpression of a DN mutant of dynamin II reduced the entry and infection, suggesting that dynamin mediates the fission and detachment of clathrin- and cholesterol-pits for entry of this strain. In contrast, the inhibition of caveolae-mediated endocytosis using nystatin, siRNAs, or a DN mutant had no inhibitory effect on entry and infection of this strain. It was further determined that cell entry of PSaV Cowden strain required actin rearrangements for vesicle internalization, endosomal trafficking from early to late endosomes through microtubules, and late endosomal acidification for uncoating. We conclude that PSaV strain Cowden is internalized into LLC-PK cells by clathrin- and cholesterol-mediated endocytosis that requires dynamin II and actin rearrangement, and that the uncoating occurs in the acidified late endosomes after trafficking from the early endosomes through microtubules
Porcine Sapelovirus Uses α2,3-Linked Sialic Acid on GD1a Ganglioside as a Receptor.
UNLABELLED: The receptor(s) for porcine sapelovirus (PSV), which causes diarrhea, pneumonia, polioencephalomyelitis, and reproductive disorders in pigs, remains largely unknown. Given the precedent for other picornaviruses which use terminal sialic acids (SAs) as receptors, we examined the role of SAs in PSV binding and infection. Using a variety of approaches, including treating cells with a carbohydrate-destroying chemical (NaIO4), mono- or oligosaccharides (N-acetylneuraminic acid, galactose, and 6'-sialyllactose), linkage-specific sialidases (neuraminidase and sialidase S), lectins (Maakia amurensislectin andSambucus nigralectin), proteases (trypsin and chymotrypsin), and glucosylceramide synthase inhibitors (dl-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol and phospholipase C), we demonstrated that PSV could recognize α2,3-linked SA on glycolipids as a receptor. On the other hand, PSVs had no binding affinity for synthetic histo-blood group antigens (HBGAs), suggesting that PSVs could not use HBGAs as receptors. Depletion of cell surface glycolipids followed by reconstitution studies indicated that GD1a ganglioside, but not other gangliosides, could restore PSV binding and infection, further confirming α2,3-linked SA on GD1a as a PSV receptor. Our results could provide significant information on the understanding of the life cycle of sapelovirus and other picornaviruses. For the broader community in the area of pathogens and pathogenesis, these findings and insights could contribute to the development of affordable, useful, and efficient drugs for anti-sapelovirus therapy. IMPORTANCE: The porcine sapelovirus (PSV) is known to cause enteritis, pneumonia, polioencephalomyelitis, and reproductive disorders in pigs. However, the receptor(s) that the PSV utilizes to enter host cells remains largely unknown. Using a variety of approaches, we showed that α2,3-linked terminal sialic acid (SA) on the cell surface GD1a ganglioside could be used for PSV binding and infection as a receptor. On the other hand, histo-blood group antigens also present in the cell surface carbohydrates could not be utilized as PSV receptors for binding and infection. These findings should contribute to the understanding of the sapelovirus life cycle and to the development of affordable, useful and efficient drugs for anti-sapelovirus therapy.This study was supported by Wellcome Trust (097997/Z/11/Z) and a grant from Basic Science Research Program through the National Research Foundation of Korea (NRF). This study was also supported by Bio-industry Technology Development Program through the Korea Institute of Planning and Evaluation for Technology in Food, Agriculture, Forestry and Fisheries (iPET) funded by the Ministry of Agriculture, Food and Rural Affairs, and Chonnam National University (2013). IG is a Wellcome Senior Fellow supported by the Wellcome Trust (097997/Z/11/Z).This is the final version of the article. It first appeared from the American Society for Microbiology via http://dx.doi.org/10.1128/JVI.02449-1
Pathogenesis of Korean SapelovirusA in piglets and chicks.
Sapelovirus A (SV-A), formerly known as porcine sapelovirus as a member of a new genus Sapelovirus, is known to cause enteritis, pneumonia, polioencephalomyelitis and reproductive disorders in pigs. We have recently identified α2,3-linked sialic acid on GD1a ganglioside as a functional SV-A receptor rich in the cells of pigs and chickens. However, the role of GD1a in viral pathogenesis remains elusive. Here, we demonstrated that a Korean SV-A strain could induce diarrhoea and intestinal pathology in piglets but not in chicks. Moreover, this Korean SV-A strain had mild extra-intestinal tropisms appearing as mild, non-suppurative myelitis, encephalitis and pneumonia in piglets, but not in chicks. By real-time reverse transcription (RT) PCR, higher viral RNA levels were detected in faecal samples than in sera or extra-intestinal organs from virus-inoculated piglets. Immunohistochemistry confirmed that high viral antigens were detected in the epithelial cells of intestines from virus-inoculated piglets but not from chicks. This Korean SV-A strain could bind the cultured cell lines originated from various species, but replication occurred only in cells of porcine origin. These data indicated that this Korean SV-A strain could replicate and induce pathology in piglets but not in chicks, suggesting that additional porcine-specific factors are required for virus entry and replication. In addition, this Korean SV-A strain is enteropathogenic, but could spread to the bloodstream from the gut and disseminate to extra-intestinal organs and tissues. These results will contribute to our understanding of SV-A pathogenesis so that efficient anti-sapelovirus drugs and vaccines could be developed in the future.This study was supported by a grant (2014R1A2A2A01004292) of the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning, Bio-industry Technology Development Program (315021-04) through the Korea Institute of Planning and Evaluation for Technology in Food, Agriculture, Forestry and Fisheries (iPET) funded by the Ministry of Agriculture, Food and Rural Affairs, and Korea Basic Science Institute grant (C33730), Republic of Korea. IG is a Wellcome Senior Fellow supported by the Wellcome Trust (097997/Z/11/Z). Chonnam National University provided funding to Mun-Il Kang (2012). The Mab against SV-A capsid protein was received as a generous gift from Dr. M. Dauber (Friedrich-Loeffler Institute, Germany).This is the accepted version of the article. The final version is available from the Microbiology Society via http://dx.doi.org/10.1099/jgv.0.00057
Center-Guided Transformer for Panoptic Segmentation
A panoptic segmentation network to predict masks and classes for things and stuff in images is proposed in this work. Recently, panoptic segmentation has been advanced through the combination of the query-based learning and end-to-end learning approaches. Current research focuses on learning queries without distinguishing between thing and stuff classes. We present decoupling query learning to generate effective thing and stuff queries for panoptic segmentation. For this purpose, we adopt different workflows for thing and stuff queries. We design center-guided query selection for thing queries, which focuses on the center regions of individual instances in images, while we set stuff queries as randomly initialized embeddings. Also, we apply a decoupling mask to the self-attention of query features to prevent interactions between things and stuff. In the query selection process, we generate a center heatmap that guides thing query selection. Experimental results demonstrate that the proposed panoptic segmentation network outperforms the state of the art on two panoptic segmentation datasets
Direct preparation of edge-propylene graphitic nanoplatelets and its reinforcing effects in polypropylene
Directly, edge-propylene graphitic nanoplatelets (EPGnPs) are made easily using only solid graphite and propylene gas via the mechanical chemistry without additional reactions. The edge-propylene functionalization is confirmed using various analytical techniques (e.g. FT-IR, EA, and TEM). The hydrophobic characteristic and outstanding properties of the EPGnPs make it suitable as a new reinforcing additive for polyolefins such as polypropylene (PP). In result, the tensile strength, yield strength, and Young's modulus of EPGnP/PP_5 nanocomposites are enhanced 90.5, 90.8, and 249.5%, respectively and also show the higher thermal stability compared with raw PP due to its remarkable properties as well as the enhanced affinity between PP and propylene-functional groups of the EPGnPs. Based on experimental results, the graphitic nanoplatelets (GnPs) with various functional groups, especially, hydrophobicity, offer a number of advantages (e.g., excellent compatibility, economy, and mass-production) for use as a filler to expand the applications of polyolefin composites
BTENet: Back-Fat Thickness Estimation Network for Automated Grading of the Korean Commercial Pig
For the automated grading of the Korean commercial pig, we propose deep neural networks called the back-fat thickness estimation network (BTENet). The proposed BTENet contains segmentation and thickness estimation modules to simultaneously perform a back-fat area segmentation and a thickness estimation. The segmentation module estimates a back-fat area mask from an input image. Through both the input image and estimated back-fat mask, the thickness estimation module predicts a real back-fat thickness in millimeters by effectively analyzing the back-fat area. To train BTENet, we also build a large-scale pig image dataset called PigBT. Experimental results validate that the proposed BTENet achieves the reliable thickness estimation (Pearson’s correlation coefficient: 0.915; mean absolute error: 1.275 mm; mean absolute percentage error: 6.4%). Therefore, we expect that BTENet will accelerate a new phase for the automated grading system of the Korean commercial pig
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