Astrocytes play a pivotal role in maintaining the central nervous system (CNS) homeostasis and function. In response to CNS injuries and diseases, reactive astrocytes are triggered. By purifying and ...genetically profiling reactive astrocytes, it has been now found that astrocytes can be activated into two polarization states: the neurotoxic or pro-inflammatory phenotype (A1) and the neuroprotective or anti-inflammatory phenotype (A2). Although the simple dichotomy of the A1/A2 phenotypes does not reflect the wide range of astrocytic phenotypes, it facilitates our understanding of the reactive state of astrocytes in various CNS disorders. This article reviews the recent evidences regarding A1/A2 astrocytes, including (a) the specific markers and morphological characteristics, (b) the effects of A1/A2 astrocytes on the neurovascular unit, and (c) the molecular mechanisms involved in the phenotypic switch of astrocytes. Although many questions remain, a deeper understanding of different phenotypic astrocytes will eventually help us to explore effective strategies for neurological disorders by targeting astrocytes.
•A1/A2 astrocytes and their specific markers are closely related to various CNS injuries and diseases.•A1/A2 astrocytes have diverse effects on the neurovascular unit in CNS injuries and diseases.•The local extracellular and intracellular signals regulate phenotypic switch of astrocytes.•Targeting A1/A2 astrocytes may be a potential strategy for most neurological disorders.
Catechins are natural polyphenolic phytochemicals that exist in food and medicinal plants, such as tea, legume and rubiaceae. An increasing number of studies have associated the intake of ...catechins-rich foods with the prevention and treatment of chronic diseases in humans, such as inflammatory bowel disease (IBD). Some studies have demonstrated that catechins could significantly inhibit the excessive oxidative stress through direct or indirect antioxidant effects and promote the activation of the antioxidative substances such as glutathione peroxidases (GPO) and glutathione (GSH), reducing the oxidative damages to the colon. In addition, catechins can also regulate the infiltration and proliferation of immune related-cells, such as neutrophils, colonic epithelial cells, macrophages, and T lymphocytes, helping reduce the inflammatory relations and provide benefits to IBD. Perhaps catechins can further inhibit the deterioration of intestinal lesions through regulating the cell gap junctions. Furthermore, catechins can exert their significant anti-inflammatory properties by regulating the activation or deactivation of inflammation-related oxidative stress-related cell signaling pathways, such as nuclear factor-kappa B (NF-κB), mitogen activated protein kinases (MAPKs), transcription factor nuclear factor (erythroid-derived 2)-like 2 (Nrf2), signal transducer and the activator of transcription 1/3 (STAT1/3) pathways. Finally, catechins can also stabilize the structure of the gastrointestinal micro-ecological environment via promoting the proliferation of beneficial intestinal bacteria and regulating the balance of intestinal flora, so as to relieve the IBD. Furthermore, catechins may regulate the tight junctions (TJ) in the epithelium. This paper elaborates the currently known possible molecular mechanisms of catechins in favor of IBD.
Cysteine hydropersulfide (CysSSH) occurs in abundant quantities in various organisms, yet little is known about its biosynthesis and physiological functions. Extensive persulfide formation is ...apparent in cysteine-containing proteins in Escherichia coli and mammalian cells and is believed to result from post-translational processes involving hydrogen sulfide-related chemistry. Here we demonstrate effective CysSSH synthesis from the substrate L-cysteine, a reaction catalyzed by prokaryotic and mammalian cysteinyl-tRNA synthetases (CARSs). Targeted disruption of the genes encoding mitochondrial CARSs in mice and human cells shows that CARSs have a crucial role in endogenous CysSSH production and suggests that these enzymes serve as the principal cysteine persulfide synthases in vivo. CARSs also catalyze co-translational cysteine polysulfidation and are involved in the regulation of mitochondrial biogenesis and bioenergetics. Investigating CARS-dependent persulfide production may thus clarify aberrant redox signaling in physiological and pathophysiological conditions, and suggest therapeutic targets based on oxidative stress and mitochondrial dysfunction.
Although the photodimerization of acenaphthylene (ACE) has been known for 100 years, the asymmetric cycloaddition of its 1‐substituted derivatives is unknown. Herein, we report a supramolecular ...photochirogenic approach in which a homochiral and photoactive Δ/Λ‐Pd6(RuL3)828+ metal–organic cage (Δ/Λ‐MOC‐16) is used as a supramolecular reactor for the enantioselective exited‐state photocatalysis of 1‐Br‐ACE. Owing to preorganization of the substrates by the supramolecular cage, stereochemical control of the triplet state, and nanospace transfer of energy and chirality, the cycloaddition of ACE proceeded with high selectivity for the formation of anti over syn stereoisomers, whereas the regio‐, stereo‐, and enantioselective cycloaddition of unsymmetrical 1‐Br‐ACE showed effective enantiodifferentiation of a pair of anti head‐to‐head stereoisomers. The enzyme‐mimicking photocatalysis was verified by catalytic turnover, rate enhancement, and competing‐guest inhibition experiments.
Control freak: A photoactive homochiral metal–organic cage (MOC) promoted the stereo‐, regio‐, and enantioselective 2+2 cycloaddition of an acenaphthylene derivative in a supramolecular catalytic sense under sustainable conditions (see picture). The high regio‐ and stereoselectivity resulted from preorganization of the substrates by the supramolecular cage, stereochemical control of the triplet state, and nanospace transfer of energy and chirality.
A novel approach for the ultrasensitive detection and separation of F- has been successfully developed. F- could induce a tripodal naphthalene imide sensor (TNA) to result in supramolecular ...polymerization, leading to strong AIEE. The TNA could act as an excellent recyclable material for F- detection and separation.
Abstract
For decades, the major focus of redox biology has been oxygen, the most abundant element on Earth. Molecular oxygen functions as the final electron acceptor in the mitochondrial respiratory ...chain, contributing to energy production in aerobic organisms. In addition, oxygen‐derived reactive oxygen species including hydrogen peroxide and nitrogen free radicals, such as superoxide, hydroxyl radical and nitric oxide radical, undergo a complicated sequence of electron transfer reactions with other biomolecules, which lead to their modified physiological functions and diverse biological and pathophysiological consequences (e.g. oxidative stress). What is now evident is that oxygen accounts for only a small number of redox reactions in organisms and knowledge of biological redox reactions is still quite limited. This article reviews a new aspects of redox biology which is governed by redox‐active sulfur‐containing molecules—supersulfides. We define the term ‘supersulfides’ as sulfur species with catenated sulfur atoms. Supersulfides were determined to be abundant in all organisms, but their redox biological properties have remained largely unexplored. In fact, the unique chemical properties of supersulfides permit them to be readily ionized or radicalized, thereby allowing supersulfides to actively participate in redox reactions and antioxidant responses in cells. Accumulating evidence has demonstrated that supersulfides are indispensable for fundamental biological processes such as energy production, nucleic acid metabolism, protein translation and others. Moreover, manipulation of supersulfide levels was beneficial for pathogenesis of various diseases. Thus, supersulfide biology has opened a new era of disease control that includes potential applications to clinical diagnosis, prevention and therapeutics of diseases.
▶ A core network of brain regions underlies empathy across all stimuli and tasks. ▶ This network consists of the dACC-aMCC-SMA and bilateral anterior insula. ▶ Cognitive–evaluative and ...affective–perceptual empathy differ neurally. ▶ C–E empathy involves dorsal aMCC specifically; A–P empathy the right AI.
Whilst recent neuroimaging studies have identified a series of different brain regions as being involved in empathy, it remains unclear concerning the activation consistence of these brain regions and their specific functional roles. Using MKDA, a whole-brain based quantitative meta-analysis of recent fMRI studies of empathy was performed. This analysis identified the dACC-aMCC-SMA and bilateral anterior insula as being consistently activated in empathy. Hypothesizing that what are here termed affective–perceptual and cognitive–evaluative forms of empathy might be characterized by different activity patterns, the neural activations in these forms of empathy were compared. The dorsal aMCC was demonstrated to be recruited more frequently in the cognitive–evaluative form of empathy, whilst the right anterior insula was found to be involved in the affective–perceptual form of empathy only. The left anterior insula was active in both forms of empathy. It was concluded that the dACC-aMCC-SMA and bilateral insula can be considered as forming a core network in empathy, and that cognitive–evaluative and affective–perceptual empathy can be distinguished at the level of regional activation.
A recent progress in new emerging two-dimensional (2D) materials has provided promising opportunity for gas sensing in ultra-low detectable concentration. In this work, we have demonstrated a ...flexible NO
2
gas sensor with porous structure graphene on polyethylene terephthalate substrates operating at room temperature. The gas sensor exhibited good performance with response of 1.2% and a fast response time within 30 s after exposure to 50 × 10
−9
NO
2
gas. As porous structure of graphene increased the surface area, the sensor showed high sensitivity of ppb level for NO
2
detection. Au nanoparticles were decorated on the surface of the porous structure graphene skeleton, resulting in an incensement of response compared with pristine graphene. Au nanoparticles-decorated graphene exhibits not only better sensitivity (1.5–1.6 times larger than pristine graphene) for NO
2
gas detection, but also fast response. The sensor was found to be robust and sensitive under the cycling bending test, which could also be ascribed to the merits of graphene. This porous structure graphene-based gas sensor is expected to enable a simple and inexpensive flexible gas sensing platform.
Graphic Abstract
The photoinduced regio‐ and enantioselective coupling of naphthols and derivatives thereof is achieved in the confined chiral coordination space of a RuII metalloligand based cage. The racemic or ...enantiopure cages encapsulate naphthol guests, which then undergo a regiospecific 1,4‐coupling, rather than the normal 1,1‐coupling, to form 4‐(2‐hydroxy‐1‐naphthyl)‐1,2‐napthoquinones; moderate stereochemical control is achieved with homochiral cages. The photoreactions proceed under both aerobic and anaerobic conditions but through distinct pathways that nevertheless involve the same radical intermediates. This unusual dimerization constitutes a very rare example of asymmetric induction in biaryl coupling by making use of coordination cages with dual functionality—photoredox reactivity and stereoselectivity.
Confined coordination spaces in redox‐active ruthenium(II) cages enable the photoinduced regio‐ and enantioselective coupling of naphthol and derivatives thereof. The photoreactions proceed under both aerobic and anaerobic conditions but by distinct pathways that nevertheless involve the same radical intermediates.
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