Structure of the PAPP-ABP5 complex reveals mechanism of substrate recognition

Insulin-like growth factor (IGF) signaling is highly conserved and tightly regulated by proteases including Pregnancy-Associated Plasma Protein A (PAPP-A). PAPP-A and its paralog PAPP-A2 are metalloproteases that mediate IGF bioavailability through cleavage of IGF binding proteins (IGFBPs). Here, we present single-particle cryo-EM structures of the catalytically inactive mutant PAPP-A (E483A) in complex with a peptide from its substrate IGFBP5 (PAPP-A_BP5) and also in its substrate-free form, by leveraging the power of AlphaFold to generate a high quality predicted model as a starting template. We show that PAPP-A is a flexible trans-dimer that binds IGFBP5 via a 25-amino acid anchor peptide which extends into the metalloprotease active site. This unique IGFBP5 anchor peptide that mediates the specific PAPP-A-IGFBP5 interaction is not found in other PAPP-A substrates. Additionally, we illustrate the critical role of the PAPP-A central domain as it mediates both IGFBP5 recognition and trans-dimerization. We further demonstrate that PAPP-A trans-dimer formation and distal inter-domain interactions are both required for efficient proteolysis of IGFBP4, but dispensable for IGFBP5 cleavage. Together the structural and biochemical studies reveal the mechanism of PAPP-A substrate binding and selectivity.

Flexible Two-Dimensional Vanadium Carbide MXene-Based Membranes with Ultra-Rapid Molecular Enrichment for Surface-Enhanced Raman Scattering

Two-dimensional (2D) MXene materials have attracted broad interest in surface-enhanced Raman scattering (SERS) applications by virtue of their abundant surface terminations and excellent photoelectric properties. Herein, we propose to design highly sensitive MXene-based SERS membranes by integrating a 2D downsizing strategy with molecular enrichment approaches. Two types of 2D vanadium carbide (V₄C₃ and V₂C) MXenes are demonstrated for ultrasensitive SERS sensing, and corresponding SERS mechanisms including the effect of 2D vanadium carbide thickness on their electron density states and interfacial photoinduced charge transfer resonance were discussed. A 2D downsizing strategy authorizes nonplasmonic SERS detection with a sensitivity of 1 × 10^-7 M. Moreover, the performance can be further upgraded by vacuum-assisted filtration, which enables an ultrarapid molecular enrichment (within 2 min), ultrahigh molecular removal rate (over 95%), and improved sensitivity (5 × 10^-9 M). This work may shed light on the MXene-based materials as an innovative platform for nonplasmonic SERS detection.

How trust in coworkers fosters knowledge sharing in virtual teams? A multilevel moderated mediation model of psychological safety, team virtuality, and self-efficacy

Examining the influence of trust in fostering knowledge sharing behavior (KSB) in virtual teams is of great research value in the current complex, dynamic, and competitive era of a knowledge economy. This study investigated the relationship between trust in coworkers (TC) and KSB. Based on social information processing theory and social cognitive theory, we developed a multilevel moderated mediation model where the team members’ psychological safety (PS) was considered a mediator, while team virtuality (TV) and knowledge sharing self-efficacy (KSSE) acted as team and individual-level moderators, respectively. On surveying 282 individuals in 37 virtual teams of three Chinese internet companies, we found that TC positively affected team members’ KSB and this relationship was fully mediated by team members’ PS. Our findings also demonstrated that the effect of TC on KSB depended on the degree of TV and employees’ KSSE. Specifically, when TV and KSSE were higher, the TC–PS and PS–KSB relationship and the mediating effects of PS in the TC–PS–KSB relationship were all stronger. Our study extends the trust-KSB literature by identifying the psychological mechanism and boundary conditions in the TC-KSB relationship. Moreover, our findings also offer valuable managerial implications for virtual team managers on facilitating team members’ PS and KSB.

Systematic lymphatic abnormality-related osseous lesions: a study based on CT lymphangiography

Background

Few studies have focused on the morphology of systematic lymphatic abnormality-related osseous lesions. In this study, we classified systematic lymphatic abnormality-related osseous lesions into four types based on their morphology and density. We also discussed the imaging features of computed tomography lymphangiography (CTL) in this disease.

Methods

In this retrospective cohort study, the clinical and imaging data of 39 patients with systematic lymphatic abnormality-related osseous lesions were collected. All patients underwent computed tomography (CT) scans of the chest and abdomen after direct lymphangiography, and two experienced radiologists evaluated the CTL features of intraosseous and extraosseous lymphatic vessel abnormalities.

Results

Intraosseous osteolytic changes were observed in all 39 patients. According to the morphological density of the lesions, systematic lymphatic abnormality-related osseous lesions were classified into four types: cyst-like (76.9%), canal-like or honeycomb-like (87.2%), osteoporosis-like (41.0%), and osteosclerosis-like (20.5%), with abnormal deposits of lipiodol seen in the first two types. Enhanced CT of the thorax and abdomen was performed in 11 cases, and enhancement was not seen in any intraosseous lesions.

Conclusions

The CTL features of systematic lymphatic abnormality-related osseous lesions have specific characteristics and are often accompanied by extraosseous abnormalities, which can provide a vital imaging basis for the diagnosis and differentiation of this disease.

Hyaluronic acid restored protein permeability across injured human lung microvascular endothelial cells

Lung endothelial permeability is a key pathological feature of acute respiratory distress syndrome. Hyaluronic acid (HA), a major component of the glycocalyx layer on the endothelium, is generated by HA synthase (HAS) during inflammation and injury and is critical for repair. We hypothesized that administration of exogenous high molecular weight (HMW) HA would restore protein permeability across human lung microvascular endothelial cells (HLMVEC) injured by an inflammatory insult via upregulation of HAS by binding to CD44. A transwell coculture system was used to study the effects of HA on protein permeability across HLMVEC injured by cytomix, a mixture of IL‐1β, TNFα, and IFNγ, with or without HMW or low molecular weight (LMW) HA. Coincubation with HMW HA, but not LMW HA, improved protein permeability following injury at 24 h. Fluorescence microscopy demonstrated that exogenous HMW HA partially prevented the increase in “actin stress fiber” formation. HMW HA also increased the synthesis of HAS2 mRNA expression and intracellular HMW HA levels in HLMVEC following injury. Pretreatment with an anti‐CD44 antibody or 4‐methylumbelliferone, a HAS inhibitor, blocked the therapeutic effects. In conclusion, exogenous HMW HA restored protein permeability across HLMVEC injured by an inflammatory insult in part through upregulation of HAS2.

Electromagnetic Mechanisms or Chemical Mechanisms? Role of Interfacial Charge Transfer in the Plasmonic Metal/Semiconductor Heterojunction

The plasmonic metal/semiconductor heterojunction provides a unique paradigm for manipulating light to improve the efficiency of plasmonic materials. Previous studies suggest that the improvement originates from the enhanced carrier exchanges between the plasmonic component of the heterojunction and molecules. This viewpoint, known as the chemical mechanism, is reasonable but insufficient, because the construction of the heterojunction will lead to a charge redistribution in the plasmonic component and cause changes in its physical characteristics. Herein, we will try to clarify that these changes are decisive factors in specific applications by investigating the surface-enhanced Raman scattering (SERS) behavior of a typical Ag/TiO₂ heterojunction. We observed significant changes in SERS spectra by modulating the band alignment of the heterojunction in a loop. Identical trends in SERS spectra were observed despite the fact that the charge transfer from the heterojunction to molecules was blocked, suggesting that the major SERS enhancement originates from electromagnetic mechanisms rather than chemical ones.

Esophageal cancer-related gene 4 and solid tumors: a brief literature review

Esophageal cancer-related gene 4 (ECRG4) plays key roles in various malignancies, including lung cancer, prostate cancer, esophageal cancer, and breast cancer, and has potential applications in the early diagnosis, prevention, treatment, and prognosis of cancer. However, the mechanisms underlying the role of ECRG4 in cancer remain elusive. An association between ECRG4 and proliferation, migration, cell cycle, apoptosis, methylation, and ubiquitination in cancer has been found. Additionally, some studies have investigated the regulatory mechanism of the relationship between ECRG4 and long non-coding RNAs, co-factors, and resistance to chemotherapy. Drugs that demethylate ECRG4 are in clinical use. Thus, further investigation of the mechanisms by which ECRG4 influences tumorigenesis, and its clinical significance, are needed. The present study outlines the current understanding of the functions of ECRG4 in cancer and discusses its potential value in cancer therapy.

Isoleucine stimulates mTOR and SREBP-1c gene expression for milk synthesis in mammary epithelial cells through BRG1-mediated chromatin remodelling

Several amino acids can stimulate milk synthesis in mammary epithelial cells (MEC); however, the regulatory role of isoleucine (Ile) and underlying molecular mechanism remain poorly understood. In this study, we aimed to evaluate the regulatory effects of Ile on milk protein and fat synthesis in MEC and reveal the mediation mechanism of Brahma-related gene 1 (BRG1) on this regulation. Ile dose dependently affected milk protein and fat synthesis, mechanistic target of rapamycin (mTOR) phosphorylation, sterol regulatory element binding protein 1c (SREBP-1c) expression and maturation, and BRG1 protein expression in bovine MEC. Phosphatidylinositol 3 kinase (PI3K) inhibition by LY294002 treatment blocked the stimulation of Ile on BRG1 expression. BRG1 knockdown and gene activation experiments showed that it mediated the stimulation of Ile on milk protein and fat synthesis, mTOR phosphorylation, and SREBP-1c expression and maturation in MEC. ChIP-PCR analysis detected that BRG1 bound to the promoters of mTOR and SREBP-1c, and ChIP-qPCR further detected that these bindings were increased by Ile stimulation. In addition, BRG1 positively regulated the binding of H3K27ac to these two promoters, while it negatively affected the binding of H3K27me3 to these promoters. BRG1 knockdown blocked the stimulation of Ile on these two gene expressions. The expression of BRG1 was higher in mouse mammary gland in the lactating period, compared with that in the puberty or dry period. Taken together, these experimental data reveal that Ile stimulates milk protein and fat synthesis in MEC via the PI3K-BRG1-mTOR/SREBP-1c pathway.

In situ bridging nanotwinned all-solid-state Z-scheme g-C3N4/CdCO3/CdS heterojunction photocatalyst by metal oxide for H2 evolution

Nanotwin and all-solid-state (ASS) Z-scheme heterojunction engineering are two widely used strategies for improving photocatalytic activity in H₂ production. However, both strategies fail to produce a satisfactory effect when used alone due to their own limitations. Hence, combining nanotwin and ASS Z-scheme heterojunction engineering is expected to improve photocatalytic activity effectively. Herein, we report a nanotwinned ASS Z-scheme g-C₃N₄/CdCO₃/CdS (CN/CC/CS) photocatalyst synthesized for the first time by in situ bridging of (CN) and (CS) with a (CC) conductor. The growth and ripening of CN/CC/CS are limited by thiourea (Tu) and CN. CN/CC/CS can improve charge carrier separation and transfer kinetics due to the synergetic advantages of its nanotwin structure, ASS Z-scheme junction, N-Cd chemically bonded interfaces, in situ intimate contact, and hierarchical architecture. The visible-light-driven H₂ production rate of CN/CC/CS is 345% of that of CN/CS. This work proposes a new method for rationally designing novel materials with improved photocatalytic activity by combining heterojunction and defect engineering.

Viscoacoustic wave equations for the power-law dependence of Q on frequency

The power-law dependence of the quality factor Q on frequency (i.e. Q = Q 0 | f / f 0 | γ ), which is called the power-law frequency-dependent Q for brevity, is a common phenomenological description of seismic wave attenuation in the interior of the Earth. The wave equation in differential form is essential to forward and inverse modelling of dissipative seismic waveforms in an accurate and efficient manner. However, all existing methods are seemingly unable to explicitly incorporate the exponent parameter γ into the wave equation in differential form. This drawback apparently limits the development of gradient-based inverse methods for spatially varying γ via the wave equation. In this paper, we use a weighting function method to derive the viscoacoustic wave equations for the power-law frequency-dependent Q , which explicitly involve the parameters γ and Q 0 . A critical step in this method is to construct a dissipative model, for which the complex modulus is expressed as an N -order series in terms of the weighting function. Numerical examples are used to illustrate the accuracy of the dissipative model, the effect of γ on waveforms, and the application of the newly proposed wave equations in viscoacoustic wavefield modelling for the power-law frequency-dependent Q .

Stabilization of crystal and interfacial structure of Ni-rich cathode material by vanadium-doping

Stable structure and interface of nickel-rich metal oxides is crucial for practical application of next generation lithium-ion batteries with high energy density. Bulk doping is the promising strategy to improve the structural and interfacial stability of the materials. Herein, we report the impact of vanadium-doping on the structure and electrochemical performance of LiNi_0.88Co_0.09Al_0.03O₂ (NCA88). Vanadium doped in high oxidation state (+5) would lead to alteration of the crystal lattice and Li⁺/Ni²⁺ cation mixing. Those are the main factors determining the cycling and rate capability of the materials. With optimization of vanadium-doping, the preservation of the integrity of the secondary particles of the materials, the enhancement of the diffusion of Li⁺ ions, and alleviation of the side reactions of the electrolyte can be efficiently achieved. As a result, NCA88 doped with vanadium of 1.5 mol % can provide superior cycling stability with capacity retention of 84.3% after 250 cycles at 2C, and rate capability with capacity retention of 65.5% at 10C, as compared to the corresponding values of 58.6% and 55% for the pristine counterpart, respectively. The results might be helpful to the selection of dopants in the design of the nickel-rich materials.

Therapeutic Effects of Hyaluronic Acid Against Cytotoxic Extracellular Vesicles Released During Pseudomonas Aeruginosa Pneumonia

ABSTRACT

Extracellular vesicles (EVs) have now been recognized as important mediators of cellular communication during injury and repair. We previously found that plasma EVs isolated from ex vivo perfused human lungs injured with Escherichia coli bacterial pneumonia were inflammatory, and exogenous administration of high molecular weight (HMW) hyaluronic acid (HA) as therapy bound to these EVs, decreasing inflammation and injury. In the current study, we studied the role of EVs released during severe Pseudomonas aeruginosa (PA) pneumonia in mice and determined whether intravenous administration of exogenous HMW HA would have therapeutic effects against the bacterial pneumonia. EVs were collected from the bronchoalveolar lavage fluid (BALF) of mice infected with PA103 by ultracentrifugation and analyzed by NanoSight and flow cytometry. In a cytotoxicity assay, administration of EVs released from infected mice (I-EVs) decreased the viability of A549 cells compared to EV isolated from sham control mice (C-EVs). Either exogenous HMW HA or an anti-CD44 antibody, when co-incubated with I-EVs, significantly improved the viability of the A549 cells. In mice with PA103 pneumonia, administration of HMW HA improved pulmonary edema and bacterial count in the lungs and decreased TNF-α and caspase-3 levels in the supernatant of lung homogenates. In conclusion, EVs isolated from BALF of mice with P. aeruginosa pneumonia were cytotoxic and inflammatory, and intravenous HMW HA administration was protective against P. aeruginosa pneumonia.

Boosting Electrochemical Carbon Dioxide Reduction on Atomically Dispersed Nickel Catalyst

Single-atom catalysts (SACs) with metal–nitrogen (M–N) sites are one of the most promising electrocatalysts for electrochemical carbon dioxide reduction (ECO₂R). However, challenges in simultaneously enhancing the activity and selectivity greatly limit the efficiency of ECO₂R due to the improper interaction of reactants/intermediates on these catalytic sites. Herein, we report a carbon-based nickel (Ni) cluster catalyst containing both single-atom and cluster sites (NiNx-T, T = 500–800) through a ligand-mediated method and realize a highly active and selective electrocatalytic CO₂R process. The catalytic performance can be regulated by the dispersion of Ni–N species via controlling the pyrolysis condition. Benefitting from the synergistic effect of pyrrolic-nitrogen coordinated Ni single-atom and cluster sites, NiNx-600 exhibits a satisfying catalytic performance, including a high partial current density of 61.85 mA cm⁻² and a high turnover frequency (TOF) of 7,291 h⁻¹ at −1.2 V vs. RHE, and almost 100% selectivity toward carbon monoxide (CO) production, as well as good stability under 10 h of continuous electrolysis. This work discloses the significant role of regulating the coordination environment of the transition metal sites and the synergistic effect between the isolated single-site and cluster site in enhancing the ECO₂R performance.

[Immediate rehabilitation of edentulous mandibles with implant-supported full-arch prostheses by intra-oral welding technique: a two-year follow-up]

Objective: To evaluate the 2-year clinical outcome of immediate loading implant-supported fixed full-arch prostheses in mandibles using intra-oral welding technique and to discuss the characteristics of the technique. Methods: Totally 15 patients (4 males and 11 females) who treated with immediate rehabilitation of edentulous mandibles with implant-supported full-arch prostheses from July 2015 to February 2019 in Department of Implantology, Peking University School and Hospital of Stomatology were included in the present study. The patients' average age was 64.2±9.3 years. In each case, 4 implants were placed in the mandible area, a titanium bar was connected with each of the implants by using intra-oral welding technique as the Ti-metal framework of the prostheses. Pre-fabricated abutment-level fixed prostheses were delivered immediately after the surgery. A total of 60 implants, 15 mandibles were treated. Biological and mechanical complications, hygiene of the tissue-contacted surface of the restoration and patients' satisfactory grade were recorded. The radiological fitness of welded frameworks to abutments, survival rate of implants and marginal bone loss were calculated and analyzed. The observation period of the study was 24-55 months, with an average of 34.9 months. Results: All of the 15 cases of welded bar-abutment frameworks were fixed on implants with well passive fitness in clinical and radiological level. However, 2 of the 60 implants were failed by loss of osseointegration, and the result of implant survival rate of 96.7% in 2 years. The average marginal bone loss was (0.7±0.2) mm. The average bleeding index of the 58 implants remained was under 3 without clinical signs of gingival swelling, tenderness or fistula. No mechanical complications, such as break or distortion of the implants, occurred. Fracture of artificial teeth and complex resin area happened in 6 of the 15 prostheses. The average debris index was 3.4±0.4 and the hygiene of the tissue-contact areas was under satisfactory condition. Conclusions: Using the intra-oral welding technique to achieve a rigid splint of implants, the clinical outcome of the newly performed technique was predictable in early stage. The frame structure remained stable to avoiding the occurrence of mechanical complications. The provisional restoration could be expected to provide long functional period. Long term result of the treatment were needed for further observation.

Manipulating Hot-Electron Injection in Metal Oxide Heterojunction Array for Ultrasensitive Surface-Enhanced Raman Scattering

Efficient photoinduced charge transfer (PICT) resonance is crucial to the surface-enhanced Raman scattering (SERS) performance of metal oxide substrates. Herein, we venture into the hot-electron injection strategy to achieve unprecedented enhanced PICT efficiency between substrates and molecules. A heterojunction array composed of plasmonic MoO₂ and semiconducting WO_3-x is designed to prove the concept. The plasmonic MoO₂ generates intense localized surface plasmon resonance under illumination, which can generate near-field Raman enhancement as well as accompanied plasmon-induced hot-electrons. The hot-electron injection in direct interfacial charge transfer and plasmon-induced charge transfer process can effectively promote the PICT efficiency between substrates and molecules, achieving a record Raman enhancement factor among metal oxide substrates (2.12 × 10⁸) and the ultrasensitive detection of target molecule down to 10^-11 M. This work demonstrates the possibility of hot-electron manipulation to realize unprecedented Raman enhancement in metal oxides, offering a cutting-edge strategy to design high-performance SERS substrates.

The analysis of osteosarcopenia as a risk factor for fractures, mortality, and falls

Osteosarcopenia is defined as the concomitant occurrence of sarcopenia and osteoporosis/osteopenia. This study aimed to clarify whether osteosarcopenia implies a greater risk of fractures, mortality, and falls and to draw attention to osteosarcopenia.

INTRODUCTION

Osteosarcopenia, which is characterized by the co-existence of osteoporosis/osteopenia and sarcopenia, is one of the most challenging geriatric syndromes. However, the association between osteosarcopenia and the risk of falls, fractures, disability, and mortality is controversial.

METHODS

We searched PubMed, Embase, and the Cochrane Central Register of Controlled Trials, from their inception to March 18, 2021, for cohort studies on the relationship between osteosarcopenia and fractures, falls, and mortality. Two reviewers independently extracted data and assessed study quality. A pooled analysis was performed to calculate odds ratios (ORs) and 95% confidence intervals (CIs) using fixed or random-effects models.

RESULTS

Eight cohort studies including 19,836 participants showed that osteosarcopenia significantly increased the risk of fracture (OR 2.46, 95% CI 1.83-3.30, P_{heterogeneity} = 0.006, I² = 63.0%), three cohort studies involving 2601 participants indicated that osteosarcopenia significantly increased the risk of mortality (OR 1.66, 95% CI 1.23-2.26, P_{heterogeneity} = 0.214, I² = 35.2%), and three cohort studies involving 3144 participants indicated that osteosarcopenia significantly increased the risk of falls (OR 1.62, 95% CI 1.28-2.04, P_{heterogeneity} = 0.219, I² = 34.1%). No publication bias existed among the studies regarding the association between osteosarcopenia and fractures. The findings were robust according to the subgroup and sensitivity analyses.

CONCLUSIONS

This pooled analysis demonstrated that osteosarcopenia significantly increased the risk of fractures, falls, and mortality, thus highlighting its relevance in daily life. Therefore, we suggest that elderly persons should be aware of the risks associated with osteosarcopenia.

Association between novel variants in BMPR1B gene and litter size in Mongolia and Ujimqin sheep breeds

Prolificacy is an important trait of animals, specifically for sheep. The Bone morphogenetic protein receptor 1B (BMPR1B) is a major gene affecting the litter size of many sheep breeds. The well-known FecB mutation (Q249R) was associated fully with the hyper prolific phenotype of Booroola Merino. However, the identification of variation in all exonic regions of BMPR1B was rare. In this study, we sequenced all exonic regions of BMPR1B gene of Mongolia sheep breed, and ten novel variants were detected by direct sequencing. Among them, the litter size of the Mongolia ewes with the CC genotype was significantly higher (0.34 additional lambs, p < .05) than those with the TT genotype of the g.29346567C>T single nucleotide polymorphism (SNP). The litter size of the Mongolia ewes with the TT genotype was significantly higher (0.19 additional lambs, p < .05 and .31 additional lambs, p < .01, respectively) than those with the GT and GG genotypes of the c.1470G>T SNP. The silent c.1470G>T mutation is predicted to increase the stability of the mRNA secondary structure through reducing minimum free energy and is predicted to change the mRNA secondary structure of BMPR1B. Our findings may give potentially useful genetic markers for increasing litter size in sheep.

Down-regulation of betatrophin enhances insulin sensitivity in type 2 diabetes mellitus through activation of the GSK-3β/PGC-1α signaling pathway

OBJECTIVE

The incidence of type 2 diabetes mellitus (T2DM) among children and adolescents has been rising. Accumulating evidences have noted the significant role of betatrophin in the regulation of lipid metabolism and glucose homeostasis. In our study, we tried to figure out the underlying mechanism of betatrophin in insulin resistance (IR) in type 2 diabetes mellitus (T2DM).

METHODS

First, fasting serum betatrophin, fasting blood glucose (FBG), insulin, total cholesterol (TC), triglyceride (TG), and low-density lipoprotein cholesterol (LDL-C) were detected in T2DM children. The homeostasis model assessment of insulin resistance (HOMA-IR), Gutt insulin sensitivity index (ISI_G) and Matsuda insulin sensitivity index (ISI_M) were calculated. A T2DM-IR mouse model was induced by high-fat diet, with the expression of GSK-3β and PGC-1α detected. Besides, HepG2 cells were induced by a high concentration of insulin to establish an IR cell model (HepG2-IR). The cell viability, glucose consumption, liver glycogen content, inflammation, and fluorescence level of GSK-3β and PGC-1α were analyzed.

RESULTS

Betatrophin was highly expressed in serum of T2DM children and was positively correlated with FBG, insulin, TC, TG, LDL-C and HOMA-IR, while negatively correlated with ISI_G and ISI_M. Betatrophin and GSK-3β in the liver tissues of T2DM-IR mice were increased, while the PGC-1α expression was decreased. Betatrophin expression was negatively correlated with PGC-1α and positively correlated with GSK-3β. Silencing of betatrophin enhanced insulin sensitivity through the activation of GSK-3β/PGC-1α signaling pathway. In vitro experiments also found that silencing of betatrophin promoted glucose consumption and glycogen synthesis while inhibited inflammation.

CONCLUSION

Our findings concluded that silencing of betatrophin could enhance insulin sensitivity and improve histopathological morphology through the activation of GSK-3β/PGC-1α signaling pathway.