265 research outputs found
Molecular characterization, structural analysis and determination of host range of a novel bacteriophage LSB-1
<p>Abstract</p> <p>Background</p> <p>Bacteriophages (phages) are widespread in the environment and play a crucial role in the evolution of their bacterial hosts and the emergence of new pathogens.</p> <p>Results</p> <p>LSB-1, a reference coliphage strain, was classified as a member of the Podoviridae family with a cystic form (50 ± 5 nm diameter) and short tail (60 ± 5 nm long). The double stranded DNA was about 30 kilobase pairs in length. We identified its host range and determined the gp17 sequences and protein structure using shotgun analysis and bioinformatics technology.</p> <p>Conclusions</p> <p>Coliphage LSB-1 possesses a tailspike protein with endosialidase activity which is probably responsible for its specific enteroinvasive <it>E.coli </it>host range within the laboratory.</p
Heterotypic cell-cell interaction of human stem cells for neural differentiation of hybrid spheroids
Organoids, the condensed 3-D tissues emerged at the early stage of organogenesis, are a promising approach to regenerate functional and vascularized organ mimics [1]. While incorporation of heterotypic cell types such as human mesenchymal stem cells (hMSCs) and human induced pluripotent stem cells (hiPSCs) derived neural progenitors aid neural organ development, the interactions of secreted factors during neurogenesis have not been well understood. The objective of this study is to investigate the impact of the composition and structure of 3-D hybrid spheroids of hiPSCs and hMSCs on dorsal cortical differentiation and the secretion of extracellular matrices and trophic factors in vitro. The hybrid spheroids were formed at different hiPSC:hMSC ratios (100:0, 75:25, 50:50, 25:75, 0:100) using direct mixing or pre-hiPSC aggregation method, which generated dynamic spheroid structure. The cellular organization, proliferation, neural marker expression, the secretion of extracellular matrix proteins and the cytokines were characterized. The incorporation of MSCs upregulated Nestin and β-tubulin III expression (the dorsal cortical identity was shown by Pax6 and TBR1 expression), matrix remodeling proteins and the secretion of transforming growth factor-β1 and prostaglandin E2. This study indicates that the appropriate composition and structure of hiPSC-MSC spheroids promote neural differentiation and trophic factor and matrix secretion due to the heterotypic cell-cell interactions.
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Uplink Contention Based SCMA for 5G Radio Access
Fifth generation (5G) wireless networks are expected to support very diverse
applications and terminals. Massive connectivity with a large number of devices
is an important requirement for 5G networks. Current LTE system is not able to
efficiently support massive connectivity, especially on the uplink (UL). Among
the issues arise due to massive connectivity is the cost of signaling overhead
and latency. In this paper, an uplink contention-based sparse code multiple
access (SCMA) design is proposed as a solution. First, the system design
aspects of the proposed multiple-access scheme are described. The SCMA
parameters can be adjusted to provide different levels of overloading, thus
suitable to meet the diverse traffic connectivity requirements. In addition,
the system-level evaluations of a small packet application scenario are
provided for contention-based UL SCMA. SCMA is compared to OFDMA in terms of
connectivity and drop rate under a tight latency requirement. The simulation
results demonstrate that contention-based SCMA can provide around 2.8 times
gain over contention-based OFDMA in terms of supported active users. The uplink
contention-based SCMA scheme can be a promising technology for 5G wireless
networks for data transmission with low signaling overhead, low delay, and
support of massive connectivity.Comment: Submitted to Golobecom 5G workshop 201
Intestinal Cgi-58 Deficiency Reduces Postprandial Lipid Absorption
Comparative Gene Identification-58 (CGI-58), a lipid droplet (LD)-associated protein, promotes intracellular triglyceride (TG) hydrolysis in vitro. Mutations in human CGI-58 cause TG accumulation in numerous tissues including intestine. Enterocytes are thought not to store TG-rich LDs, but a fatty meal does induce temporary cytosolic accumulation of LDs. Accumulated LDs are eventually cleared out, implying existence of TG hydrolytic machinery in enterocytes. However, identities of proteins responsible for LD-TG hydrolysis remain unknown. Here we report that intestine-specific inactivation of CGI-58 in mice significantly reduces postprandial plasma TG concentrations and intestinal TG hydrolase activity, which is associated with a 4-fold increase in intestinal TG content and large cytosolic LD accumulation in absorptive enterocytes during the fasting state. Intestine-specific CGI-58 knockout mice also display mild yet significant decreases in intestinal fatty acid absorption and oxidation. Surprisingly, inactivation of CGI-58 in intestine significantly raises plasma and intestinal cholesterol, and reduces hepatic cholesterol, without altering intestinal cholesterol absorption and fecal neutral sterol excretion. In conclusion, intestinal CGI-58 is required for efficient postprandial lipoprotein-TG secretion and for maintaining hepatic and plasma lipid homeostasis. Our animal model will serve as a valuable tool to further define how intestinal fat metabolism influences the pathogenesis of metabolic disorders, such as obesity and type 2 diabetes
Stability and asynchrony of local communities but less so diversity increase regional stability of Inner Mongolian grassland
Extending knowledge on ecosystem stability to larger spatial scales is urgently needed because present local-scale studies are generally ineffective in guiding management and conservation decisions of an entire region with diverse plant communities. We investigated stability of plant productivity across spatial scales and hierarchical levels of organization and analyzed impacts of dominant species, species diversity, and climatic factors using a multisite survey of Inner Mongolian grassland. We found that regional stability across distant local communities was related to stability and asynchrony of local communities. Using only dominant instead of all-species dynamics explained regional stability almost equally well. The diversity of all or only dominant species had comparatively weak effects on stability and synchrony, whereas a lower mean and higher variation of precipitation destabilized regional and local communities by reducing population stability and synchronizing species dynamics. We demonstrate that, for semi-arid temperate grassland with highly uneven species abundances, the stability of regional communities is increased by stability and asynchrony of local communities and these are more affected by climate rather than species diversity. Reduced amounts and increased variation of precipitation in the future may compromise the sustainable provision of ecosystem services to human well-being in this region
Evaluating the quantum optimal biased bound in a unitary evolution process
Seeking the available precision limit of unknown parameters is a significant
task in quantum parameter estimation. One often resorts to the widely utilized
quantum Cramer-Rao bound (QCRB) based on unbiased estimators to finish this
task. Nevertheless, most actual estimators are usually biased in the limited
number of trials. For this reason, we introduce two effective error bounds for
biased estimators based on a unitary evolution process in the framework of the
quantum optimal biased bound. Furthermore, we show their estimation performance
by two specific examples of the unitary evolution process, including the phase
encoding and the SU(2) interferometer process. Our findings will provide an
useful guidance for finding the precision limit of unknown parameters.Comment: 11 pages, 3 figures, welcome comment
Distinct interactions between fronto-parietal and default mode networks in impaired consciousness
Existing evidence suggests that the default-mode network (DMN) and fronto-pariatal network (FPN) play an important role in altered states of consciousness. However, the brain mechanisms underlying impaired consciousness and the specific network interactions involved are not well understood. We studied the topological properties of brain functional networks using resting-state functional MRI data acquired from 18 patients (11 vegetative state/unresponsive wakefulness syndrome, VS/UWS, and 7 minimally conscious state, MCS) and compared these properties with those of healthy controls. We identified that the topological properties in DMN and FPN are anti-correlated which comes, in part, from the contribution of interactions between dorsolateral prefrontal cortex of the FPN and precuneus of the DMN. Notably, altered nodal connectivity strength was distance-dependent, with most disruptions appearing in long-distance connections within the FPN but in short-distance connections within the DMN. A multivariate pattern-classification analysis revealed that combination of topological patterns between the FPN and DMN could predict conscious state more effectively than connectivity within either network. Taken together, our results imply distinct interactions between the FPN and DMN, which may mediate conscious state
Microwave resonances of magnetic skyrmions in thin film multilayers
Non-collinear magnets exhibit a rich array of dynamic properties at microwave frequencies. They can host nanometre-scale topological textures known as skyrmions, whose spin resonances are expected to be highly sensitive to their local magnetic environment. Here, we report a magnetic resonance study of an [Ir/Fe/Co/Pt] multilayer hosting Néel skyrmions at room temperature. Experiments reveal two distinct resonances of the skyrmion phase during in-plane ac excitation, with frequencies between 6–12 GHz. Complementary micromagnetic simulations indicate that the net magnetic dipole moment rotates counterclockwise (CCW) during both resonances. The magnon probability distribution for the lower-frequency resonance is localised within isolated skyrmions, unlike the higher-frequency mode which principally originates from areas between skyrmions. However, the properties of both modes depend sensitively on the out-of-plane dipolar coupling, which is controlled via the ferromagnetic layer spacing in our heterostructures. The gyrations of stable isolated skyrmions reported in this room temperature study encourage the development of new material platforms and applications based on skyrmion resonances. Moreover, our material architecture enables the resonance spectra to be tuned, thus extending the functionality of such applications over a broadband frequency range
Effects of parenteral nutrition of ω-3 polyunsaturated fatty acid, arginine and glutamine on cellular immune status of patients following liver cancer surgery
Purpose: To study the effects of parenteral nutrition (TPN), ω-3 polyunsaturated fatty acid (PUFA), Larginine (Arg), and glutamine on cellular immunity of patients who have done the liver cancer (LC) surgery.Methods: Seventy-five (75) LC patients were randomly divided into 5 groups (A - E; 15 cases each), group A, B, C, D and E, in which patients were treated with TPN, TPN + fish oil, TPN + Arg, TPN + glutamine, and TPN + ω-3 PUFA + Arg + glutamine, respectively. Before and after surgery, CD3 +, CD4 + and CD8 + were measured by antibody-sensitized erythrocyte rosette test, and IL-6, IL-10 and TNF-a were assayed with double-antibody sandwich enzyme-linked immunoassay (DAS-ELISA). IgA and IgM were measured nephelometrically.Results: The levels of CD3 +, CD4 + and CD8 + in group A showed no obvious change after surgery (p > 0.05). However, CD3 + and CD4 + increased in groups B, C and D, while CD8 + decreased in group E (p < 0.05). IL-6 in group E was lower than that in any of the other four groups (p < 0.05). IL-10 in group A was lower than that in groups B, C and D, but lower than in group E (p < 0.05). The levels of TNF-a in groups B and C were lower than those in group A, but higher than that in group E (p < 0.05) but lower than in group D. IgA in group E was higher than in the other groups (p < 0.05), while IgM level in group E was lower than in groups A, B and C (p < 0.05).Conclusion: Immunosuppressive status and cellular immunity of patients after liver cancer surgery may be improved by a combination therapy of TPN, ω-3 PUFAs, Arg and glutamine.Keywords: Polyunsaturated fatty acid, Arginine, Glutamine, Parenteral nutrition, Hepatoma, Cellular immunit
Loss of Abhd5 Promotes Colorectal Tumor Development and Progression by Inducing Aerobic Glycolysis and Epithelial-Mesenchymal Transition
How cancer cells shift metabolism to aerobic glycolysis is largely unknown. Here, we show that deficiency of a/b-hydrolase domain-containing 5 (Abhd5), an intracellular lipolytic activator that is also known as comparative gene identification 58 (CGI-58), promotes this metabolic shift and enhances malignancies of colorectal carcinomas (CRCs). Silencing of Abhd5 in normal fibroblasts induces malignant transformation. Intestine-specific knockout of Abhd5 in ApcMin/+ mice robustly increases tumorigenesis and malignant transformation of adenomatous polyps. In colon cancer cells, Abhd5 deficiency induces epithelial-mesenchymal transition by suppressing the AMPKa-p53 pathway, which is attributable to increased aerobic glycolysis. In human CRCs, Abhd5 expression falls substantially and correlates negatively with malignant features. Our findings link Abhd5 to CRC pathogenesis and suggest that cancer cells develop aerobic glycolysis by suppressin
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