Publications by authors named "Meng-Meng Xu"

The scar-free healing remains a clinical challenge, and requires the concerted efforts of multiple cell types, such as keratinocytes and fibroblasts. Exosomes derived from human adipose-derived mesenchymal stem cells (hADSC-Exos) have emerged as a promising therapeutic option. Nonetheless, a thorough understanding of the mechanisms underlying regenerative healing in response to hADSC-Exos treatment is still lacking.

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Ultraviolet B (UVB) light exposure accelerates skin photoaging. Human adipose-derived stem cell exosomes (hADSC-Exos) and some antioxidants may have anti-photoaging effects. However, it is unknown whether the combination of hADSC-Exos and antioxidants plays a synergistic role in anti-photoaging.

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Electrophilic addition of alkenes is a textbook reaction that plays a pivotal role in organic chemistry. In the past decades, catalytic asymmetric variants of this important type of reaction have witnessed great achievements by the development of novel catalytic systems. However, enantioselective aza-electrophilic additions of unactivated alkenes, which could provide a transformative strategy for the preparation of synthetically significant nitrogen-containing compounds, still remain a formidable challenge.

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Article Synopsis
  • Influenza A viruses (IAV) contribute to worsening symptoms in COPD patients, leading to increased inflammation and lung damage due to abnormal macrophage responses.
  • In a study involving COPD mouse models induced by cigarette smoke, melatonin was tested for its protective effects against IAV infections, showing improved lung function and reduced inflammatory markers.
  • Melatonin was found to decrease polarization of harmful M1 macrophages and inflammation through its receptors, indicating a potential therapeutic role for melatonin in managing IAV-related COPD exacerbations.
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Here, we describe a cooperative Pd(0)/chiral phosphoric acid catalytic system that allows us to realize the first chemo-, regio-, and enantioselective sequential cross-[4 + 2]-cycloaddition/decarboxylation reaction between 2-pyrones and unactivated acyclic 1,3-dienes. The key to the success of this transformation is the utilization of an achiral heterocyclic carbene (NHC) as the ligand and a newly developed chiral phosphoric acid as the cocatalyst. Experimental investigations and computational studies support the idea that the Pd(0)/NHC complex acts as a π-Lewis base to increase the nucleophilicity of 1,3-dienes via η coordination, while the chiral phosphoric acid simultaneously increases the electrophilicity of 2-pyrones by hydrogen bonding.

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Background: The transplantation of exosomes derived from human adipose-derived mesenchymal stem cells (hADSCs) has emerged as a prospective cellular-free therapeutic intervention for the treatment of neurodevelopmental disorders (NDDs), as well as autism spectrum disorder (ASD). Nevertheless, the efficacy of hADSC exosome transplantation for ASD treatment remains to be verified, and the underlying mechanism of action remains unclear.

Results: The exosomal long non-coding RNAs (lncRNAs) from hADSC and human umbilical cord mesenchymal stem cells (hUCMSC) were sequenced and 13,915 and 729 lncRNAs were obtained, respectively.

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Background: Blended learning is being integrated into undergraduate nursing education at all levels and from all directions. Cognitive engagement is not only an embodiment and guarantee of students' engagement into the curriculum from a cognitive level, deep engagement and high-level thinking, but also an important indicator of whether students are effectively engaged in the blended learning curricula. However, no studies have been seen to investigate the cognitive engagement of nursing undergraduates in the blended learning curricula and its influential factors.

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Background: Genetics evidences have long linked mosaic loss of Y-chromosome (mLOY) in peripheral leukocytes with a wide range of male age-associated diseases. However, a lack of cellular and molecular mechanistic explanations for this link has limited further investigation into the relationship between mLOY and male age-related disease. Excitingly, Sano et al.

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Background: The gefitinib resistance mechanism in non-small cell lung cancer (NSCLC) remains unclear, albeit exosomal circular RNA (circRNA) is known to possibly play a vital role in it.

Methods: We employed high-throughput sequencing techniques to detect the expressions of exosomal circRNA both in gefitinib-resistant and gefitinib-sensitive cells in this study. The circKIF20B expression was determined in serum exosomes and tissues of patients by qRT-PCR.

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Article Synopsis
  • The study presents a method combining Birch reduction and a catalytic asymmetric Diels-Alder reaction to synthesize cis-decalin scaffolds, which are important for various chemical applications.
  • Using a specialized chiral bis(oxazoline) ligand/Cu complex, researchers efficiently produced a variety of polysubstituted cis-decalin structures, some with up to six stereocenters.
  • The synthetic capabilities were highlighted by creating the sesquiterpene (+)-occidentalol and an intermediate for seven triterpenes, with mechanistic studies indicating that certain cyclohexadienes play a crucial role in the reaction process.
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An NBS-induced intramolecular annulation of 3-(1-indol-3-yl)--alkoxypropanamide is described. The reactions proceed well and quickly under mild conditions with the help of a base. It was found that C2-substituents on the indole ring in 3-(1-indol-3-yl)--alkoxypropanamide have a great influence upon the reaction.

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We report herein an efficient approach for the enantioselective synthesis of inherently chiral calix[4]arenes via palladium-catalyzed asymmetric intramolecular C-H arylations. Using a chiral bifunctional phosphine-carboxylate ligand, the inherent chirality on macrocyclic scaffolds was induced successfully, from which a wide range of calix[4]arenes with fluorenone motifs were obtained with good yields and excellent enantioselectivities (up to >99% ee). The synthetic utility of this method was demonstrated by diverse transformations of the products, thus substantially expanding the chemical space of chiral calix[4]arenes.

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Carbon-based nanomaterials have a high specific surface area, biocompatibility, and controlled mesopore structures. These characteristics make carbon nanospheres excellent carriers for drugs, biological dyes, photosensitizers, etc. Nevertheless, little is known about the impact of topological features on the surface of carbon nanomaterials on their in vivo immunoreactivity.

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Influenza virus infection is one of the strongest pathogenic factors for the development of acute lung injury (ALI)/ acute respiratory distress syndrome (ARDS). However, the underlying cellular and molecular mechanisms have not been clarified. In this study, we aim to investigate whether melatonin modulates macrophage polarization, oxidative stress, and pyroptosis via activating Apolipoprotein E/low-density lipoprotein receptor (ApoE/LDLR) pathway in influenza A-induced ALI.

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Aim: This meta-analysis aimed to systematically evaluate the effectiveness of auricular acupressure on pain management during labor.

Methods: Six English and three Chinese electronic databases were comprehensively searched from inception to 6 November 2021. The PRISMA checklist was followed.

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Article Synopsis
  • Heterotaxy syndrome (HTX) is a condition resulting from abnormal left-right organ positioning during embryonic development, with genetic causes poorly understood in most cases.
  • Through exome sequencing of 81 HTX patients and 89 healthy controls, the study identified three novel pathogenic variants of the MMP21 gene in unrelated Chinese Han patients, suggesting a potential link to complex congenital heart defects.
  • Functional assays in zebrafish confirmed that the identified MMP21 variants lead to heart development issues, highlighting the significance of these mutations in understanding HTX pathology.
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By utilizing an underexplored reaction mode of ,-cyclic azomethine imines, a catalyst-free [1+2+3] cycloaddition/N-N bond cleavage sequential reaction for accessing spiroindolines with -stereoselectivity was developed. On the basis of experimental results and DFT calculations, peroxide and ethereal solvent were identified to trigger the hydrogen abstraction of the unstable [1+2+3] cycloaddition adducts, followed by homolytic cleavage of the N-N bond and hydrogen absorption.

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Zika virus (ZIKV) is a flavivirus that causes severe neuropathology in newborns and adults. There is no ZIKV-specific treatment or preventative. Therefore, it is urgent to develop safe and effective anti-ZIKV agents.

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Background: Age-related macular degeneration (AMD) is the leading cause of severe vision loss in patients over 55 years old in the industrialized world. In the past 20 years, approximately 288 million patents have been affected by this disease. Despite this high prevalence, the molecular mechanism for AMD remains unclear, and there remains no effective treatment for this disease.

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Calcium induced calcium release signaling (CICR) plays a critical role in many biological processes. Every cellular activity from cell proliferation and apoptosis, development and ageing, to neuronal synaptic plasticity and regeneration have been associated with Ryanodine receptors (RyRs). Despite the importance of calcium signaling, the exact mechanism of its function in early development is unclear.

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Article Synopsis
  • Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) involve severe inflammation and oxidative stress, leading to lung damage and reduced survival rates.
  • The study investigates whether melatonin can protect against ALI caused by LPS by activating a specific signaling pathway (Nrf2/HO-1) and reducing a process called pyroptosis in both animal models and human cell lines.
  • Results showed that melatonin treatment not only improved lung health but also inhibited harmful molecules and inflammatory responses linked to ALI, suggesting its potential as a protective agent against this condition.
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The human body is colonized by densely-populated and structurally complex communities of microorganisms. The microbiota interact not only with their host cells, but also with other microbiota. Dual RNA sequencing (Dual RNA-seq) can be used to conduct simultaneous analysis of the dynamic changes of gene expression of two (or more) interactive species, and to obtain thus, through the interaction model diagram, the inter-species regulatory relationship of genes of different species, and hence the interaction mechanism between species.

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Acute lung injury (ALI) is a common and devastating clinical disorder featured by excessive inflammatory responses. Stimulator of interferon genes (STING) is an indispensable molecule for regulating inflammation and immune response in multiple diseases, but the role of STING in the ALI pathogenesis is not well elucidated. In this study, we explored the molecular mechanisms of STING in regulating lipopolysaccharide (LPS)-induced lung injury.

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An inverse-electron-demand Diels-Alder (IEDDA) reaction could complement the conventional normal-electron-demand Diels-Alder reaction in the synthesis of six-membered carbocycles. However, catalytic asymmetric all-carbon-based IEDDA reactions are underdeveloped. Herein, we disclosed a copper-catalyzed asymmetric IEDDA reaction using electron-deficient 3-carboalkoxyl-2-pyrones and electronically unbiased indenes as reactants.

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The enantioselective synthesis of axially chiral biaryls by a copper-catalyzed Diels-Alder/retro-Diels-Alder reaction of 2-pyrones with alkynes is reported herein. Using electron-deficient 2-pyrones and electron-rich 1-naphthyl acetylenes as the reaction partners, a broad range of axially chiral biaryl esters are obtained in excellent yields (up to 97% yield) and enantioselectivities (up to >99% ee). DFT calculations reveal the reaction mechanism and provide insights into the origins of the stereoselectivities.

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