Vascular calcification refers to the pathological deposition of calcium and phosphate minerals into the vasculature. It is prevalent in atherosclerosis, ageing, type 2 diabetes mellitus and chronic ...kidney disease, thus, increasing morbidity and mortality from these conditions. Vascular calcification shares similar mechanisms with bone mineralization, with smooth muscle cells playing a critical role in both processes. In the last decade, a variety of microRNAs have been identified as key regulators for the differentiation, phenotypic switch, proliferation, apoptosis, cytokine production and matrix deposition in vascular smooth muscle cells during vascular calcification. Therefore, this review mainly discusses the roles of microRNAs in the pathophysiological mechanisms of vascular calcification in smooth muscle cells and describes several interventions against vascular calcification by regulating microRNAs. As the exact mechanisms of calcification remain not fully elucidated, having a better understanding of microRNA involvement in vascular calcification may give impetus to development of novel therapeutics for the control and treatment of vascular calcification.
The homeostatic link between oxidative stress and autophagy plays an important role in cellular responses to a wide variety of physiological and pathological conditions. However, the regulatory ...pathway and outcomes remain incompletely understood. Here, we show that reactive oxygen species (ROS) function as signaling molecules that regulate autophagy through ataxia‐telangiectasia mutated (ATM) and cell cycle checkpoint kinase 2 (CHK2), a DNA damage response (DDR) pathway activated during metabolic and hypoxic stress. We report that CHK2 binds to and phosphorylates Beclin 1 at Ser90/Ser93, thereby impairing Beclin 1‐Bcl‐2 autophagy‐regulatory complex formation in a ROS‐dependent fashion. We further demonstrate that CHK2‐mediated autophagy has an unexpected role in reducing ROS levels via the removal of damaged mitochondria, which is required for cell survival under stress conditions. Finally, CHK2−/− mice display aggravated infarct phenotypes and reduced Beclin 1 p‐Ser90/Ser93 in a cerebral stroke model, suggesting an in vivo role of CHK2‐induced autophagy in cell survival. Taken together, these results indicate that the ROS‐ATM‐CHK2‐Beclin 1‐autophagy axis serves as a physiological adaptation pathway that protects cells exposed to pathological conditions from stress‐induced tissue damage.
Synopsis
Whether hypoxia and nutrient starvation are coupled to cellular autophagy remains unclear. Here, DNA damage response kinases ATM and CHK2 are shown to trigger autophagy in response to reactive oxygen species (ROS) accumulation, suggesting a novel physiological adaptation pathway toward metabolic stress.
Depletion of CHK2 or ATM impairs oxidative stress‐induced autophagy in MEFs.
CHK2 binds and phosphorylates Beclin1 at Ser90/Ser93, suppressing Beclin1‐Bcl‐2 autophagy regulatory complex formation.
CHK2‐induced autophagy limits intracellular ROS levels by clearing damaged mitochondria.
CHK2‐induced autophagy protects against cell death and tissue damage following cerebral ischemia.
ROS accumulation activates protective autophagy to prevent stress‐induced tissue damage.
Nonsymmorphic symmetries, which involve fractional lattice translations, can generate exotic types of fermionic excitations in crystalline materials. Here we propose a topological phase arising from ...nonsymmorphic symmetries-the hourglass Dirac chain metal, and predict its realization in the rhenium dioxide. We show that ReO
features hourglass-type dispersion in the bulk electronic structure dictated by its nonsymmorphic space group. Due to time reversal and inversion symmetries, each band has an additional two-fold degeneracy, making the neck crossing-point of the hourglass four-fold degenerate. Remarkably, close to the Fermi level, the neck crossing-point traces out a Dirac chain-a chain of connected four-fold-degenerate Dirac loops-in the momentum space. The symmetry protection, the transformation under symmetry-breaking, and the associated topological surface states of the Dirac chain are revealed. Our results open the door to an unknown class of topological matters, and provide a platform to explore their intriguing physics.
Efficient hydrogen evolution via electrocatalytic water splitting holds great promise in modern energy devices. Herein, we demonstrate that the localized surface plasmon resonance (LSPR) excitation ...of Au nanorods (NRs) dramatically improves the electrocatalytic hydrogen evolution activity of CoFe‐metal–organic framework nanosheets (CoFe‐MOFNs), leading to a more than 4‐fold increase of current density at −0.236 V (vs. RHE) for Au/CoFe‐MOFNs composite under light irradiation versus in dark. Mechanistic investigations reveal that the hydrogen evolution enhancement can be largely attributed to the injection of hot electrons from AuNRs to CoFe‐MOFNs, raising the Fermi level of CoFe‐MOFNs, facilitating the reduction of H2O and affording decreased activation energy for HER. This study highlights the superiority of plasmonic excitation on improving electrocatalytic efficiency of MOFs and provides a novel avenue towards the design of highly efficient water‐splitting systems under light irradiation.
Some like it hot: A composite of Au nanorods/CoFe‐MOF nanosheets (Au/CoFe‐MOFNs) was used as an electrocatalyst for the hydrogen evolution reaction (HER). Au/CoFe‐MOFNs give a four‐fold increase of current density and a much reduced activation energy upon light irradiation as a result of hot‐electron injection from plasmonic Au to CoFe‐MOFNs.
Mesenchymal stem cells (MSCs)-derived extracellular vesicles (EVs) have been reported to exhibit therapeutic effects in various animal models of neurological diseases, such as stroke and ...hypoxic-ischemic brain injury.
The present study investigated the potential beneficial effect of MSC-derived EVs in an animal model of Alzheimer's disease (AD).
APP/PS1 mice and their non-transgenic littermates (WT) received intracerebroventricle injection of MSC-derived EVs once per two days for two weeks. Then novel object recognition and water maze tasks were carried out to measure the cognitive behaviors. Electrophysiological tests were carried out to measure hippocampal synaptic plasticity. Inducible nitric oxide synthase (iNOS) mRNA and protein levels were measured by qRT-PCR and western blotting in primary cultured neurons treated with amyloid-β peptide (Aβ) or prepared from APP/PS1 mice.
Treatment with MSC-derived EVs alleviates exogenous Aβ-induced iNOS mRNA and protein expression. In cultured primary neurons prepared from APP/PS1 pups, iNOS mRNA and protein levels were significantly reduced when treated with MSC-derived EVs. MSC-derived EVs improved cognitive behavior, rescued impairment of CA1 synaptic transmission, and long-term potentiation in APP/PS1 mice.
MSC-derived EVs possessed beneficial effects in a mouse model of AD, probably by suppressing Aβ induced iNOS expression.
The rapidly spreading outbreak of COVID-19 disease is caused by the SARS-CoV-2 virus, first reported in December 2019 in Wuhan, China. As of June 17, 2020, this virus has infected over 8.2 million ...people but ranges in symptom severity, making it difficult to assess its overall infection rate. There is a need for rapid and accurate diagnostics to better monitor and prevent the spread of COVID-19. In this review, we present and evaluate two main types of diagnostics with FDA-EUA status for COVID-19: nucleic acid testing for detection of SARS-CoV-2 RNA, and serological assays for detection of SARS-CoV-2 specific IgG and IgM patient antibodies, along with the necessary sample preparation for accurate diagnoses. In particular, we cover and compare tests such as the CDC 2019-nCoV RT-PCR Diagnostic Panel, Cellex's qSARS-CoV-2 IgG/IgM Rapid Test, and point-of-care tests such as Abbott's ID NOW COVID-19 Test. Antibody testing is especially important in understanding the prevalence of the virus in the community and to identify those who have gained immunity. We conclude by highlighting the future of COVID-19 diagnostics, which include the need for quantitative testing and the development of emerging biosensors as point-of-care tests.
•Current standard-of-care for COVID-19 diagnosis is RT-PCR, used to detect SARS-CoV-2 viral RNA.•Serological assays for detection of SARS-CoV-2 specific IgG and IgM antibodies are useful to assess virus prevalence.•Point-of-care tests for COVID-19 diagnoses can expedite results and alleviate the burden placed on healthcare providers.•Future testing strategies include developing quantitative COVID-19 diagnostic tools.
The change of bonding status, typically occurring only in chemical processes, could dramatically alter the material properties. Here, we show that a tunable breaking and forming of a diatomic bond ...can be achieved through physical means, i.e., by a moderate biaxial strain, in the newly discovered MoN2 two-dimensional (2D) material. On the basis of first-principles calculations, we predict that as the lattice parameter is increased under strain, there exists an isostructural phase transition at which the N–N distance has a sudden drop, corresponding to the transition from a N–N nonbonding state to a N–N single bond state. Remarkably, the bonding change also induces a magnetic phase transition, during which the magnetic moments transfer from the N(2p) sublattice to the Mo(4d) sublattice; meanwhile, the type of magnetic coupling is changed from ferromagnetic to antiferromagnetic. We provide a physical picture for understanding these striking effects. The discovery is not only of great scientific interest in exploring unusual phase transitions in low-dimensional systems, but it also reveals the great potential of the 2D MoN2 material in the nanoscale mechanical, electronic, and spintronic applications.
An ultrasensitive Panda-microfiber (PMF)-based multimode interferometer for salinity measurement is proposed and demonstrated. By inserting a section of PMF supporting a few modes into a conventional ...optical fiber system, an inline interference between the high-order modes of PMF, i.e., TE 01 and TM 01 , is realized. The sensitivity is as high as 2938.16 pm/ 0 / 00 and its resolution is up to 0.0014 0 / 00 (0.0001 S/m), which is two magnitudes higher than other fiber salinity sensors. With the features of compactness, reconfigurability, stability, and compatibility with other fiberized components, PMF has great potential in tunable filtering, multiwavelength lasing, etc.
Abstract The objective of this systematic review and meta-analysis was to investigate whether the administration of branched-chain amino acids (BCAAs) reduces exercise-induced muscle damage (EIMD) ...markers following eccentric exercise (EE) compared to a placebo (PL). The Cochrane bias risk tool and NutriGrade scale were used to critically evaluate the included studies. Forest plots were used to visualize the standardized mean differences (SMD) and p-values. The included studies were randomized controlled trials with either a placebo or crossover randomized design. The assessment of EIMD markers was compared between the intervention (BCAA) and placebo situations at 0, 24, 48, 72, and 96 hours after the EE protocol. Subgroup analyses were conducted to assess the effects of BCAA intake on creatine kinase concentration based on follow-up times (immediately, 24 hours, 48 hours, 72 hours, 96 hours), dosage (≥ 10 g/day, < 10 g/day), administration duration (≥ 1 week, < 1 week), exercise type (aerobic, anaerobic), and training status (trained, untrained). The intervention situation showed a significant reduction in indirect markers of EIMD compared to the placebo situation (p = 0.001; I2 = 81%). Subgroup analyses indicated that BCAA administration had a significant reducing effect on creatine kinase levels in trials with a dosage of ≥ 10 g/day, anaerobic exercise, trained individuals, and an ingestion duration of less than 1 week. The findings of this study suggest that BCAA administration reduces EIMD markers following chronic EE in both trained and untrained individuals. BCAA administration reduces creatine kinase activity at 48 hours, 72 hours, and overall post-EE compared to a placebo.
Dendrobium is known for its pharmacological actions including anti-cancer effect, anti-fatigue effect, gastric ulcer protective effect, and so on. At present, only studies on endophytic fungi of ...Dendrobium affecting the metabolites of host plants have been reported, very little research has been done on endophytic bacteria. In this study, we have demonstrated the great diversity of endophytic bacteria in 6 Dendrobium samples from different origins and cultivars. According to the results of the culture-independent method, the endophytic bacterial community in Dendrobium stems showed obvious different in the 6 samples and was influenced by origin and cultivar. Some bacteria including Ralstonia, Comamonas and Lelliottia were first detected in Dendrobium in this study. Based on the culture-dependent method, a total of 165 cultivable endophytic bacteria isolates were isolated from the sterilized Dendrobium stems, and were classified into 43 species according to the 16S rRNA gene sequence analysis. Moreover, 14 of the 43 strains showed antimicrobial activity against phytopathogen using the Kirby-Bauer method. Strain NA-HTong-7 (Bacillus megaterium, 99.12%) showed the highest antimicrobial activity. This study was the first comprehensive study on endophytic bacteria of Dendrobium from different origins and cultivars, which provides new insights into the endophytic bacteria from Dendrobium.
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