With the aim of mimicking biological machines, in which the delicate arrangement of nanomechanical units lead to the output of specific functions upon the external stimulus, the construction of dual ...stimuli-responsive rotaxane-branched dendrimers was realized in this study. Starting from a switchable organometallic 2rotaxane precursor, the employment of a controllable divergent approach allowed for the successful synthesis of a family of rotaxane-branched dendrimers up to the third generation with 21 switchable rotaxane moieties located on each branch. More importantly, upon the addition and removal of dimethylsulfoxide (DMSO) molecule or acetate anion as the external stimulus, the amplified responsiveness of the switchable rotaxane units endowed the resultant rotaxane-branched dendrimers the solvent- or anion-controlled molecular motions, thus leading to the dimension modulation. Therefore, we successfully constructed a family of rotaxane-branched dendrimers with dual stimuli-responsiveness that will be a privileged platform for the construction of dynamic supramolecular materials.
Diarylselenides are a representative class of molecules in organoselenium compounds. We herein report a Rh-catalyzed direct diarylation of selenium with benzamide derivatives. The use of elemental ...selenium as the Se source is intriguing in terms of atom economy, cost, stability, and handling. A series of diarylselenides with amide moieties were readily accessible through directed C–H activation. The intermediacy of electrophilic Se(IV) species was indicated by control experiments.
Lilium is a large genus that includes approximately 110 species distributed throughout cold and temperate regions of the Northern Hemisphere. The species-level phylogeny of Lilium remains unclear; ...previous studies have found universal markers but insufficient phylogenetic signals. In this study, we present the use of complete chloroplast genomes to explore the phylogeny of this genus. We sequenced nine Lilium chloroplast genomes and retrieved seven published chloroplast genomes for comparative and phylogenetic analyses. The genomes ranged from 151,655 bp to 153,235 bp in length and had a typical quadripartite structure with a conserved genome arrangement and moderate divergence. A comparison of sixteen Lilium chloroplast genomes revealed ten mutation hotspots. Single nucleotide polymorphisms (SNPs) for any two Lilium chloroplast genomes ranged from 8 to 1,178 and provided robust data for phylogeny. Except for some of the shortest internodes, phylogenetic relationships of the Lilium species inferred from the chloroplast genome obtained high support, indicating that chloroplast genome data will be useful to help resolve the deeper branches of phylogeny.
N6‐Methyladenosine (m6A) modification has been implicated in many biological processes. However, its role in cancer has not been well studied. Here, we demonstrate that m6A modifications are ...decreased in hepatocellular carcinoma, especially in metastatic hepatocellular carcinoma, and that methyltransferase‐like 14 (METTL14) is the main factor involved in aberrant m6A modification. Moreover, METTL14 down‐regulation acts as an adverse prognosis factor for recurrence‐free survival of hepatocellular carcinoma and is significantly associated with tumor metastasis in vitro and in vivo. We confirm that METTL14 interacts with the microprocessor protein DGCR8 and positively modulates the primary microRNA 126 process in an m6A‐dependent manner. Further experiments show that microRNA 126 inhibits the repressing effect of METTL14 in tumor metastasis. Conclusion: These studies reveal an important role of METTL14 in tumor metastasis and provide a fresh view on m6A modification in tumor progression. (Hepatology 2017;65:529‐543).
Ischemia stroke is known as the major cause of morbidity and mortality. Buyang Huanwu Decoction (BHD), a classical traditional Chinese medicine (TCM) formula, has been used to prevent and treat stoke ...for hundreds of years. The purpose of present study is to investigate the effects of BHD on angiogenesis in rats after cerebral ischemia/reperfusion (I/R) injury targeting Silent information regulator 1 (SIRT1) / Vascular endothelial growth factor (VEGF) pathway.
The cerebral I/R injury model was induced by middle cerebral artery occlusion (MCAO). Adult Sprag-Dawley (SD) rats were randomly divided into five groups: sham group, normal saline (NS) group, BHD group, BHD+EX527 (SIRT1 specific inhibitor) group, and NS+EX527 group. Each group was divided into the subgroups according to 1, 3, 7, or 14 days time-point after cerebral ischemia/reperfusion, respectively. Neurological function score (NFS) was evaluated by the Rogers scale; microvascular density (MVD) in brain tissue around infarction area was observed by immunofluorescence; and the expression of SIRT1 and VEGF was assessed by Western Blot and Quantitative Real-time-PCR.
BHD can significantly improve NFS (
< 0.05), increase the MVD in the boundary ischemic area (
< 0.01) and elevate the expression of protein and mRNA of SIRT1 and VEGF following I/R injury (
< 0.01). In contrast, treatment with EX527 reversed the BHD-induced improvements in NFS (
< 0.01) and decreased the MVD (
< 0.01) and the expression of SIRT1 and VEGF (
< 0.05).
BHD exerts neuroprotection targeting angiogenesis through the up-regulation of SIRT1/VEGF pathway against cerebral ischemic injury in rats.
Borneol, a natural product in the Asteraceae family, is widely used as an upper ushering drug for various brain diseases in many Chinese herbal formulae. The blood-brain barrier (BBB) plays an ...essential role in maintaining a stable homeostatic environment, while BBB destruction and the increasing BBB permeability are common pathological processes in many serious central nervous system (CNS) diseases, which is especially an essential pathological basis of cerebral ischemic injury. Here, we aimed to conduct a systematic review to assess preclinical evidence of borneol for experimental ischemic stroke as well as investigate in the possible neuroprotective mechanisms, which mainly focused on regulating the permeability of BBB. Seven databases were searched from their inception to July 2018. The studies of borneol for ischemic stroke in animal models were included. RevMan 5.3 was applied for data analysis. Fifteen studies investigated the effects of borneol in experimental ischemic stroke involving 308 animals were ultimately identified. The present study showed that the administration of borneol exerted a significant decrease of BBB permeability during cerebral ischemic injury according to brain Evans blue content and brain water content compared with controls (P<0.01). In addition, borneol could improve neurological function scores (NFS) and cerebral infarction area. Thus, borneol may be a promising neuroprotective agent for cerebral ischemic injury, largely through alleviating the BBB disruption, reducing oxidative reactions, inhibiting the occurrence of inflammation, inhibiting apoptosis, and improving the activity of lactate dehydrogenase (LDH) as well as P-glycoprotein (P-GP) and NO signaling pathway.
Medulloblastoma (MB) is the most common malignant pediatric brain tumor. Despite great improvements in the therapeutic regimen, relapse and leptomeningeal dissemination still pose great challenges to ...the long‐term survival of MB patients. Developing more effective strategies has become extremely urgent. In recent years, a number of malignancies, including MB, have been found to contain a subpopulation of cancer cells known as cancer stem cells (CSCs), or tumor initiating/propagating cells. The CSCs are thought to be largely responsible for tumor initiation, maintenance, dissemination, and relapse; therefore, their pivotal roles have revealed them to be promising targets in MB therapy. Our growing understanding of the major medulloblastoma molecular subgroups and the derivation of some of these groups from specific stem or progenitor cells adds additional layers to the CSC knowledge base. Herein we review the current knowledge of MB stem cells, highlight the molecular mechanisms relating to MB relapse and leptomeningeal dissemination, and incorporate these with the need to develop more effective and accurate therapies for MB patients.
In this paper,we review the current knowledge of MB stem cells (MBSCs), highlight the molecular mechanisms in relation to MB relapse and LMD, and relate these to the need to develop more effective therapies for MB patients.
Chemical vapour deposition of two-dimensional materials typically involves the conversion of vapour precursors to solid products in a vapour–solid–solid mode. Here, we report the vapour–liquid–solid ...growth of monolayer MoS2, yielding highly crystalline ribbons with a width of few tens to thousands of nanometres. This vapour–liquid–solid growth is triggered by the reaction between MoO3 and NaCl, which results in the formation of molten Na–Mo–O droplets. These droplets mediate the growth of MoS2 ribbons in the ‘crawling mode’ when saturated with sulfur. The locally well-defined orientations of the ribbons reveal the regular horizontal motion of the droplets during growth. Using atomic-resolution scanning transmission electron microscopy and second harmonic generation microscopy, we show that the ribbons are grown homoepitaxially on monolayer MoS2 with predominantly 2H- or 3R-type stacking. Our findings highlight the prospects for the controlled growth of atomically thin nanostructure arrays for nanoelectronic devices and the development of unique mixed-dimensional structures.
Hybrid organic–inorganic perovskites have recently emerged as potential disruptive photovoltaic technology. However, the toxicity of lead used in state‐of‐the‐art hybrid perovskites solar cell ...prevents large‐scale commercialization, which calls for lead‐free alternatives. Sn‐based perovskites have been considered as alternatives but they are limited by rapid oxidation and decomposition in ambient air. Here, an Sn‐based two‐dimensional hybrid organic–inorganic perovskites A2B(n‐1)SnnI(3n+1) (n = 1 and 2) are reported with improved air stability, using bulky stilbene derivatives as the organic cations (2‐(4‐(3‐fluoro)stilbenyl)ethanammonium iodide (FSAI)). The moisture stability of the (FSA)2SnI4 perovskites is attributed to the hydrophobic properties of fluorine‐functionalized organic chains (FSA), as well as the strong cohesive bonding in the organic chains provided by H bonds, CH···X type H bonds, weak interlayer F···F interaction, and weak face‐to‐face type π‐π interactions. The photodetector device fabricated on exfoliated single crystal flake of (FSA)2SnI4 exhibits fast and stable photoconductor response.
The use of large organic cations made of stilbene derivatives is reported to generate new variants of air stable Sn‐based two‐dimensional hybrid organic–inorganic perovskites (HOIPs), (FSA)2(MA)(n–1)SnnI(3n+1) (n = 1 and 2; (2‐(4‐(3‐fluoro)stilbenyl)ethanammonium iodide = FSAI and methylammonium iodide = MAI). The single crystal of Sn‐HOIP shows excellent air stability and can be fabricated into field effect transistors and fast photodetectors.
Hypochlorous acid (HOCl), as a highly potent oxidant, is well-known as a key “killer” for pathogens in the innate immune system. Recently, mounting evidence indicates that intracellular HOCl plays ...additional important roles in regulating inflammation and cellular apoptosis. However, the organelle(s) involved in the distribution of HOCl remain unknown, causing difficulty to fully exploit its biological functions in cellular signaling pathways and various diseases. One of the main reasons lies in the lack of effective chemical tools to directly detect HOCl at subcellular levels due to low concentration, strong oxidization, and short lifetime of HOCl. Herein, the first two-photon fluorescent HOCl probe (TP-HOCl 1) and its mitochondria- (MITO-TP) and lysosome- (LYSO-TP) targetable derivatives for imaging mitochondrial and lysosomal HOCl were reported. These probes exhibit fast response (within seconds), good selectivity, and high sensitivity (<20 nM) toward HOCl. In live cell experiments, both probes MITO-TP and LYSO-TP were successfully applied to detect intracellular HOCl in corresponding organelles. In particular, the two-photon imaging of MITO-TP and LYSO-TP in murine model shows that higher amount of HOCl can be detected in both lysosome and mitochondria of macrophage cells during inflammation condition. Thus, these probes could not only help clarify the distribution of subcellular HOCl, but also serve as excellent tools to exploit and elucidate functions of HOCl at subcellular levels.
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