1,920 research outputs found
Usnic acid ameliorates bleomycin-induced pulmonary fibrosis in mice via inhibition of inflammatory responses and oxidative stress
Purpose: To Investigate the effect of usnic acid (UA) on bleomycin (BLM)-induced pulmonary fibrosis in mice, and the underlying mechanism.
Methods: Male Kunming mice with bleomycin-induced pulmonary fibrosis (PF) were exposed to different concentrations of usnic acid. Lung coefficient and histopathological changes were determined, while MDA, superoxide dismutase (SOD) activity, and expression levels of hydroxyproline, tumor necrosis factor-α, interleukins-1β & 6, and transforming growth factor-β1 were assayed in lung homogenates.
Results: UA significantly mitigated lung coefficient and histopathological changes in mice. Compared to the bleomycin group, MDA level was significantly reduced while the content of SOD markedly increased after UA pretreatment (p < 0.05). Moreover, UA significantly reduced the expression levels of all the parameters, relative to bleomycin group (p < 0.05).
Conclusion: These results indicate that UA protects mice against bleomycin-induced PF via a mechanism associated with attenuation of pro-oxidant stress and inflammation. Therefore, UA has therapeutic potential for the management of pulmonary fibrosis
Exploring the Optimal Cycle for Quantum Heat Engine using Reinforcement Learning
Quantum thermodynamic relationships in emerging nanodevices are significant
but often complex to deal with. The application of machine learning in quantum
thermodynamics has provided a new perspective. This study employs reinforcement
learning to output the optimal cycle of quantum heat engine. Specifically, the
soft actor-critic algorithm is adopted to optimize the cycle of three-level
coherent quantum heat engine with the aim of maximal average power. The results
show that the optimal average output power of the coherent three-level heat
engine is 1.28 times greater than the original cycle (steady limit). Meanwhile,
the efficiency of the optimal cycle is greater than the Curzon-Ahlborn
efficiency as well as reporting by other researchers. Notably, this optimal
cycle can be fitted as an Otto-like cycle by applying the Boltzmann function
during the compression and expansion processes, which illustrates the
effectiveness of the method
Mutation of SLC35D3 causes metabolic syndrome by impairing dopamine signaling in striatal D1 neurons
We thank Dr. Ya-Qin Feng from Shanxi Medical University, Dr. Tian-Yun Gao from Nanjing University and Dr. Yan-Hong Xue from Institute of Biophysics (CAS) for technical assistance in this study. We are very thankful to Drs. Richard T. Swank and Xiao-Jiang Li for their critical reading of this manuscript and invaluable advice. Funding: This work was partially supported by grants from National Basic Research Program of China (2013CB530605; 2014CB942803), from National Natural Science Foundation of China 1230046; 31071252; 81101182) and from Chinese Academy of Sciences (KSCX2-EW-R-05, KJZD-EW-L08). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD
Downregulation of CD147 expression alters cytoskeleton architecture and inhibits gelatinase production and SAPK pathway in human hepatocellular carcinoma cells
<p>Abstract</p> <p>Background</p> <p>CD147 plays a critical role in the invasive and metastatic activity of hepatocellular carcinoma (HCC) cells by stimulating the surrounding fibroblasts to express matrix metalloproteinases (MMPs). Tumor cells adhesion to extracellular matrix (ECM) proteins is the first step to the tumor metastasis. MMPs degrade the ECM to promote tumor metastasis. The aim of this study is to investigate the effects of small interfering RNA (siRNA) against CD147 (si-CD147) on hepatocellular carcinoma cells' (SMMC-7721) architecture and functions.</p> <p>Methods</p> <p>Flow cytometry and western blot assays were employed to detect the transfection efficiency of si-CD147. Confocal microscopy was used to determine the effects of si-CD147 on SMMC-7721 cells' cytoskeleton. Invasion assay, gelatin zymography and cell adhesion assay were employed to investigate the effects of si-CD147 on SMMC-7721 cells' invasion, gelatinase production and cell adhesive abilities. Western blot assay was utilized to detect the effects of si-CD147 on focal adhesion kinase (FAK), vinculiln and mitogen-activated protein kinase (MAPK) expression in SMMC-7721 cells.</p> <p>Results</p> <p>Downregulation of CD147 gene induced the alteration of SMMC-7721 cell cytoskeleton including actin, microtubule and vimentin filaments, and inhibited gelatinase production and expression, cells invasion, FAK and vinculin expression. si-CD147 also blocked SMMC-7721 cells adhesion to collagen IV and phosphorylation level of SAPK/JNKs. SAPK/JNKs inhibitor SP600125 inhibited gelatinase production and expression.</p> <p>Conclusion</p> <p>CD147 is required for normal tumor cell architecture and cell invasion. Downregulation of CD147 affects HCC cell structure and function. Moreover, the alteration of cell behavior may be related to SAPK/JNK Pathway. siRNA against CD147 may be a possible new approach for HCC gene therapy.</p
Fast Radio Bursts as Strong Waves Interacting with the Ambient Medium
Fast radio bursts (FRBs) are mysterious radio transients whose physical origin is still unknown. Within a few astronomical units near an FRB source, the electric field of the electromagnetic wave is so large that the electron oscillation velocity becomes relativistic, which makes the classical Thomson scattering theory and the linear plasma theory invalid. We discuss FRBs as strong waves interacting with the ambient medium, in terms of both electron motion properties and plasma properties. Several novel features are identified. (1) The cross section of Thomson scattering is significantly enhanced for the scattering photons. (2) On the other hand, because of the nonlinear plasma properties in strong waves, the near-source plasma is more transparent and has a smaller effective dispersion measure (DM) contribution to the observed value. For a repeating FRB source, the brighter bursts would have somewhat smaller DMs contributed by the near-source plasma. (3) The radiation beam undergoes relativistic self-focusing in a dense plasma, the degree of self-focusing (or squeezing) depends on the plasma density. Such a squeezing effect would affect the collimation angle and the true event rate of FRBs. (4) When an FRB propagates in a nearby ambient plasma, a wakefield wave in the plasma will be generated by the ponderomotive force of the FRB, and accelerates electrons in the ambient medium. However, such an effect is too weak to be observationally interesting
Testing the Hypothesis of Compact-binary-coalescence Origin of Fast Radio Bursts Using a Multimessenger Approach
In the literature, compact binary coalescences (CBCs) have been proposed as one of the main scenarios to explain the origin of some non-repeating fast radio bursts (FRBs). The large discrepancy between the FRB and CBC event rate densities suggests that their associations, if any, should only apply at most for a small fraction of FRBs. Through a Bayesian estimation method, we show how a statistical analysis of the coincident associations of FRBs with CBC gravitational wave (GW) events may test the hypothesis of these associations. We show that during the operation period of the advanced Laser Interferometer Gravitational-Wave Observatory (aLIGO), the detection of ~100 (~1000) GW-less FRBs with dispersion measure (DM) values smaller than 500 pc cm−3 could reach the constraint that less than 10% (or 1%) FRBs are related to binary black hole (BBH) mergers. The same number of FRBs with DM values smaller than 100 pc cm−3 is required to reach the same constraint for binary neutron star (BNS) mergers. With the upgrade of GW detectors, the same constraints for BBH and BNS mergers can be reached with fewer FRBs or looser requirements for the DM values. It is also possible to pose constraints on the fraction of each type of CBCs that are able to produce observable FRBs based on the event density of FRBs and CBCs. This would further constrain the dimensionless charge of black holes (BHs) in binary BH systems
Spatial beam self-cleaning in bi-tapered multimode fibers
We report the spatial beam self-cleaning in bi-tapered conventional multimode
fibers (MMFs) with different tapered lengths. Through the introduction of the
bi-tapered structure in MMFs, the input beam with poor beam quality from a
high-power fiber laser can be converted to a centered, bell-shaped beam in a
short length, due to the strengthened nonlinear modes coupling. It is found
that the bi-tapered MMF with longer tapered length at the same waist diameter
shows better beam self-cleaning effect and larger spectral broadening. The
obtained results offer a new method to improve the beam quality of high-power
laser at low cost. Besides, it may be interesting for manufacturing bi-tapered
MMF-based devices to obtain the quasi-fundamental mode beam in spatiotemporal
mode-locked fiber lasers
Precision Spectroscopy and Nuclear Structure Parameters in 7Li+ ion
The optical Ramsey technique is used to obtain precise measurements of the
hyperfine splittings in the 2\,^3\!S_1 and 2\,^3\!P_J states of Li.
Together with bound-state quantum electrodynamic theory, the Zemach radius and
quadrupole moment of the Li nucleus are determined to be ~fm and
~fm respectively, with the quadrupole moment deviating from the
recommended value of ~fm by . Furthermore, we
determine the quadrupole moment ratio of Li to Li as ,
exhibiting a deviation from the previous measured value of
by LiF molecular spectroscopy. The results taken together
provide a sensitive test of nuclear structure models
CT-Based Risk Factors for Mortality of Patients With COVID-19 Pneumonia in Wuhan, China: A Retrospective Study
Purpose: Computed tomography (CT) characteristics associated with critical outcomes of patients with coronavirus disease 2019 (COVID-19) have been reported. However, CT risk factors for mortality have not been directly reported. We aim to determine the CT-based quantitative predictors for COVID-19 mortality.Methods: In this retrospective study, laboratory-confirmed COVID-19 patients at Wuhan Central Hospital between December 9, 2019, and March 19, 2020, were included. A novel prognostic biomarker, V-HU score, depicting the volume (V) of total pneumonia infection and the average Hounsfield unit (HU) of consolidation areas was automatically quantified from CT by an artificial intelligence (AI) system. Cox proportional hazards models were used to investigate risk factors for mortality.Results: The study included 238 patients (women 136/238, 57%; median age, 65 years, IQR 51–74 years), 126 of whom were survivors. The V-HU score was an independent predictor (hazard ratio [HR] 2.78, 95% confidence interval [CI] 1.50–5.17; p = 0.001) after adjusting for several COVID-19 prognostic indicators significant in univariable analysis. The prognostic performance of the model containing clinical and outpatient laboratory factors was improved by integrating the V-HU score (c-index: 0.695 vs. 0.728; p < 0.001). Older patients (age ≥ 65 years; HR 3.56, 95% CI 1.64–7.71; p < 0.001) and younger patients (age < 65 years; HR 4.60, 95% CI 1.92–10.99; p < 0.001) could be further risk-stratified by the V-HU score.Conclusions: A combination of an increased volume of total pneumonia infection and high HU value of consolidation areas showed a strong correlation to COVID-19 mortality, as determined by AI quantified CT
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