Calcitonin gene-related peptide promotes proliferation and inhibits apoptosis in endothelial progenitor cells via inhibiting MAPK signaling

Abstract Background Calcitonin gene-related peptide (CGRP) contributes to bone formation by stimulating bone marrow stromal cell (BMSC) proliferation and differentiation. However, the proliferative and apoptotic effects of CGRP on bone marrow-derived endothelial progenitor cells (EPCs) have not been investigated. Methods We tested the effects of CGRP on EPC proliferation and apoptosis by Cell Counting Kit-8, flow cytometry, and studied the effects of CGRP on the expression of proliferation- and apoptosis-related markers in EPCs and the underlying mitogen-activated protein kinase (MAPK) signalling pathway by quantitative polymerase chain reaction and western blotting. Results We detected EPC markers (CD34, CD133 and VEGFR-2) in 7-day cultures and found that CGRP (10− 10–10− 12 M) promoted the proliferation of cultured EPCs, with a peak increase of 30% at 10− 10 M CGRP. CGRP also upregulated the expression of proliferation-associated genes, including cyclin D1 and cyclin E, and increased the percentages of G2/M-phase and S-phase cells after incubation 72 h. CGRP inhibited serum deprivation (SD)-induced apoptosis in EPCs after 24 and 48 h and downregulated the expression of apoptosis-related genes, including caspase-3, caspase-8, caspase-9 and Bax. Phosphorylated (p-)ERK1/2, p-p38 and p-JNK protein levels in EPCs treated with CGRP were significantly lower than those in untreated EPCs. Pre-treatment with the calcitonin receptor-like receptor (CRLR) antagonist CGRP8–37 or a MAPK pathway inhibitor (PD98059, SB203580 or SP600125) completely or partially reversed the pro-proliferative and anti-apoptotic effects and the reduced p-ERK1/2, p-p38 and p-JNK expression induced by CGRP. Conclusion Our results show that CGRP exerts pro-proliferative and anti-apoptotic effects on EPCs and may act by inhibiting MAPK pathways

Nitrogen Metabolism in Adaptation of Photosynthesis to Water Stress in Rice Grown under Different Nitrogen Levels

To investigate the role of nitrogen (N) metabolism in the adaptation of photosynthesis to water stress in rice, a hydroponic experiment supplying with low N (0.72 mM), moderate N (2.86 mM), and high N (7.15 mM) followed by 150 g⋅L-1 PEG-6000 induced water stress was conducted in a rainout shelter. Water stress induced stomatal limitation to photosynthesis at low N, but no significant effect was observed at moderate and high N. Non-photochemical quenching was higher at moderate and high N. In contrast, relative excessive energy at PSII level (EXC) was declined with increasing N level. Malondialdehyde and hydrogen peroxide (H2O2) contents were in parallel with EXC. Water stress decreased catalase and ascorbate peroxidase activities at low N, resulting in increased H2O2 content and severer membrane lipid peroxidation; whereas the activities of antioxidative enzymes were increased at high N. In accordance with photosynthetic rate and antioxidative enzymes, water stress decreased the activities of key enzymes involving in N metabolism such as glutamate synthase and glutamate dehydrogenase, and photorespiratory key enzyme glycolate oxidase at low N. Concurrently, water stress increased nitrate content significantly at low N, but decreased nitrate content at moderate and high N. Contrary to nitrate, water stress increased proline content at moderate and high N. Our results suggest that N metabolism appears to be associated with the tolerance of photosynthesis to water stress in rice via affecting CO2 diffusion, antioxidant capacity, and osmotic adjustment

Regulatory T cells-centered regulatory networks of skeletal muscle inflammation and regeneration

Abstract As the understanding of skeletal muscle inflammation is increasingly clarified, the role of Treg cells in the treatment of skeletal muscle diseases has attracted more attention in recent years. A consensus has been reached that the regulation of Treg cells is the key to completing the switch of inflammation and repair of skeletal muscle, whose presence directly determine the repairing quality of the injured skeletal muscle. However, the functioning process of Treg cells remains unreported, thereby making it necessary to summarize the current role of Treg cells in skeletal muscle. In this review, the characteristics, origins, and cellular kinetics of these Treg cells are firstly described; Then, the relationship between Treg cells and muscle satellite cells (MuSCs), conventional T cells (Tconv) is discussed (the former is involved in the entire repair and regeneration process, while the latter matters considerably in causing most skeletal muscle autoimmune diseases); Next, focus is placed on the control of Treg cells on the phenotypic switch of macrophages, which is the key to the switch of inflammation; Finally, factors regulating the functional process of Treg cells are analyzed, and a regulatory network centered on Treg cells is summarized. The present study summarizes the cell-mediated interactions in skeletal muscle repair over the past decade, and elucidates the central role of regulatory T cells in this process, so that other researchers can more quickly and comprehensively understand the development and direction of this very field. It is believed that the hereby proposed viewpoints and problems can provide fresh visions for the latecomers

Limb Reconstruction System Assisted Reduction and Internal Fixation for Intra‐Articular Calcaneal Fractures: A New Application

Background Minimally invasive reduction and fixation of intra‐articular calcaneal fractures poses great challenges for orthopaedic surgeons. The aim of the present study was to report the technical points, evaluate the efficacy of minimally invasive reduction and internal fixation assisted by the temporary limb reconstruction system (LRS) external fixator for intra‐articular calcaneal fractures, and propose the indications of our protocol. Methods In this retrospective study, a series of 34 consecutive closed and displaced intra‐articular calcaneal fractures involving the articular surface were treated by this technology between June 2016 and April 2018. X‐ray and computed tomography (CT) scans were performed before and after surgery to measure Bohler's angle; the length, height, and width of the calcaneus; and the mechanical axis of the hindfoot. Postoperative complications were recorded. Imaging and clinical outcomes were comprehensively evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot‐ankle scoring system. After testing the normality of the data, Bohler's angle and the length of calcaneus were compared using the Wilcoxon signed‐rank test. The height, width of the calcaneus, and the mechanical axis of the hindfoot were compared using the Paired‐Samples t‐test. Results Thirty‐two fractures were followed up for an average of 20.66 months (from 12 to 32 months). All fractures achieved stable reduction and bony union. The articular surface was reduced and fixed with direct vision through the sinus tarsi incision. No failure of internal fixation or loss of reduction was detected during follow‐up. There were no soft tissue complications. Bohler's angle; the length, height, and width of the calcaneus; and the mechanical axis of the hindfoot improved significantly. The AOFAS scores averaged 84.12 points; seven cases were rated excellent, 20 good, four fair, and one poor. Conclusions For intra‐articular calcaneal fractures, minimally invasive surgery assisted with temporary LRS external fixation can reconstruct the calcaneal shape and the sub‐talar articular surface. This simple surgical modality with limited complications may be helpful in the surgical treatment of most type II and III calcaneal fractures except comminuted fractures of the calcaneal tuberosity

The thickness of surface grafting layer on bio-materials directly mediates the immuno-reacitivity of macrophages in vitro

Introducing the surface grafting layers to regulate bio-compatibility and bio-function is an important step in the tissue engineering field. However, whether the thickness variation of the introduced biomimetic layer impacts the behavior of the adhered immune effector cells is yet to be dissected fully. In this study, we used a surface-induced atom transfer radical polymerization (SI-ATRP) method to synthetize and graft poly-phenoxyethyl methacrylate (PHEMA) brushes having different lengths on the glass substrates. Primary murine peritoneal macrophages were collected and cultured on the PHEMA brushes and we investigated the influence of polymer brushes having different lengths on macrophages phenotype and function. Our results demonstrated that the thicker brushes (200 nm and 450 nm) are superior to the thinner layers (50 nm) for macrophages survival, proliferation, cell elongation and migration. Moreover, the thicker brushes are more beneficial for macrophage’s activities and functions, presented by the increased production of M1-associated cytokines IL-6 and MCP-1, the elevated cell phagocytosis and the activation molecule F4/80 expression, and the reduced macrophages apoptosis in thicker brushes-sustained macrophages. Our data suggests that the thickness of the substrate grafting layer directly impacts macrophages recruitment and pro-inflammatory function, which is important in determining the intrinsic immuno-compatibilities of the surface modified-biomaterials and mediates material-host interactions in vivo

Structural basis for flg22-induced activation of the Arabidopsis FLS2-BAK1 immune complex

Flagellin perception in Arabidopsis is through recognition of its highly conserved N-terminal epitope (flg22) by flagellin-sensitive 2 (FLS2). Flg22 binding induces FLS2 heteromerization with BRASSINOSTEROID INSENSITIVE 1-associated kinase 1 (BAK1) and their reciprocal activation followed by plant immunity. Here, we report the crystal structure of FLS2 and BAK1 ectodomains complexed with flg22 at 3.06 angstroms. A conserved and a nonconserved site from the inner surface of the FLS2 solenoid recognize the C- and N-terminal segment of flg22, respectively, without oligomerization or conformational changes in the FLS2 ectodomain. Besides directly interacting with FLS2, BAK1 acts as a co-receptor by recognizing the C terminus of the FLS2-bound flg22. Our data reveal the molecular mechanisms underlying FLS2-BAK1 complex recognition of flg22 and provide insight into the immune receptor complex activation

Development and Optimization of a Two-Degree-of-Freedom Piezoelectric Harvester Based on Parallel Cantilever Structure With Magnetic Coupling

Vibration energy harvesting using the piezoelectric effect has recently attracted significant attention from scholars. The main concern in the research of piezoelectric vibration energy harvesters is to improve the operating bandwidth and output power in low-frequency vibration environments with random and time-varying nature. A novel piezoelectric vibration energy harvester (PVEH) with three parallel cantilevers and repulsive magnet pair structures is proposed in this work to achieve the above goal. The proposed PVEH has the potential to take full advantage of the synergistic effect of the multi-frequency and magnetic nonlinear performance enhancement techniques. The characteristics of the harvester are systematically studied by theoretical modeling, simulation, and experiments. The influence of the critical parameters (i.e. the tip mass of the inner beam, the tip mass of the outer beam, and the magnet spacing) on the output performance of the PVEH is discussed and optimized in detail, and then the internal mechanism of the proposed energy harvesting method based on multi-frequency and magnetic cooperation is revealed. The results show that the improvement rate of the output power of the fabricated prototype under the condition of first-order and second-order operating frequency reaches 23.35% and 38.10%, respectively, compared with the non-magnetic structure. Finally, the optimal configuration of the harvester ( $M_{\mathrm {i}}$ = 6.70 g, $M_{\mathrm {o}}$ = 5.00 g, $s=22$ mm) obtains a maximum half-power bandwidth of 1.052 Hz and a maximum output power of 2.80 mW under 0.2g with 0.155 $\text{M}\Omega$ load resistance. The proposed energy harvesting system is expected to be a promising alternative to efficient vibration energy harvesters