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A nickel-catalyzed cross-electrophile coupling of unactivated (hetero)aryl sulfones with aryl bromides via C S bond activation is developed. By relying on the use of nickel as catalyst, 2,2′-bipyridine (bpy) as ligand, and magnesium turnings as mediator, a myriad of biaryls could be facilely prepared in moderate to good yields by performing the reactions in THF at ambient temperature. [Display omitted] • Cross-electrophile coupling of unactivated (hetero)aryl sulfones could be achieved. • A variety of biaryls could be obtained with reasonable functional group tolerance. • Nickel catalyst, Mg, and THF are all indispensable for the success of the reaction. • The method avoids the use of unreadily available and sensitive organometallics. A nickel-catalyzed cross-electrophile coupling of unactivated (hetero)aryl sulfones with aryl bromides via C S bond activation at ambient temperature is developed. By relying on the use of nickel as catalyst, 2,2′-bipyridine (bpy) as ligand, magnesium turnings as mediator, and THF as solvent, a myriad of biaryls could be facilely prepared in moderate to good yields with reasonable functionality compatibility. The present method potentially serves as an attractive alternative to conventional methods, for the use of unreadily available, relatively expensive, and sensitive organometallic reagents could be avoided. [ABSTRACT FROM AUTHOR]

Mesenchymal stem cells (MSCs) have been extensively used in the field of tissue engineering and regenerative medicine. The effect of surface properties on the differentiation of MSCs is a very important issue for the design and fabrication of scaffolds or biomaterials. This review is mainly focused on the morphological or topographic characteristics of cell adhesion substrate, i.e. cell area and shape for individual cell, cell density and cell–cell contact for multiple cells, substrate roughness, ridge width, micropillar height, nanoparticle diameter and aspect ratio of nanowire. The results from different studies were quantitatively analyzed using comparable or unified parameters and definitions under the specific experimental conditions such as cell source, culture time, induction medium, matrix material and differentiation marker. Some interesting phenomena and properties were discovered by this integrated and systematic analysis, which might give insights into the regulatory mechanism of surface morphology or topography on MSCs differentiation. [ABSTRACT FROM AUTHOR]

Human regulatory T cells (Tregs) have been reported to be not significantly different in the peripheral blood of patients with chronic obstructive pulmonary disease (COPD) and healthy controls. Recent research has identified some new markers for Tregs and indicated that Tregs are composed of distinct subpopulations. The aim of the study was to describe the changing patterns of circulating Treg subpopulations in patients with acute exacerbation of COPD (AECOPD) and healthy controls, and to explore their potential roles in AECOPD pathogenesis. Blood samples were obtained from 30 never-smokers with normal lung function and 30 patients with COPD before and after they had an exacerbation. The proportions of Treg subpopulations were evaluated using flow cytometry. In the peripheral blood, decreased proportions of CD4+CD25+CD127lowTregs, CD4+CD25+CD45RA+Tregs, and CD4+CD25+CD62L+Tregs and an increased proportion of CD4+CD25+CD45RO+Tregs were found in patients with stable COPD compared with non-smokers with normal lung function. The patients showed further changes in Treg subpopulations when they had an AECOPD, with an overall decrease in a suppressive subset, indicating that the immune negative regulatory population of Tregs did not play an effective role. Immune homeostasis favored inflammation, and a negative correlation between the circulating tumor necrosis factor-alpha and the proportions of CD4+CD25+CD62L+cells (r= −0.698,p< 0.05) in patients with AECOPD was found. The imbalance between the suppressive subsets and the proinflammatory subset of Tregs and the decline of Treg subpopulations with immunosuppressive activity may play important roles in AECOPD progression. [ABSTRACT FROM AUTHOR]

Histone lysine methylation, which plays an important role in the regulation of gene expression, genome stability, chromosome conformation and cell differentiation, is a dynamic process that is collaboratively regulated by lysine methyltransferases (KMTs) and lysine demethylases (KDMs). LSD1, the first identified KDMs, catalyzes the demethylation of mono- and di-methylated H3K4 and H3K9. Here, we systematically investigated the effects of LSD1 knockdown on histone methylations. Surprisingly, in addition to H3K4 and H3K9, the methylation level on other histone lysines, such as H3K27, H3K36 and H3K79, are also increased. The expression of SOX2, E-cadherin and FoxA2 are increased upon LSD1 knockdown, and the methylation level of H3K4, H3K27 and H3K36 in the promoter region of these genes are all changed after LSD1 knockdown. Our results show that LSD1 knockdown has a broad effect on histone lysine methylation, which indicates that LSD1 regulates histone lysine methylation in collaboration with other KMTs and KDMs. [ABSTRACT FROM AUTHOR]

The distinctive hydrophobic hydration effect in the aqueous solution contributes to the success of the phospha‐Michael reaction between β‐CF3‐β,β‐disubstituted enones and diarylphosphine oxides, providing an access to biologically relevant γ‐ketophosphine oxides bearing a sterically highly congested CF3‐ and P(O)‐tetrasubstituted carbon center. More importantly, the resulting products could be further transformed into densely functionalized γ‐ketophosphine oxides containing a CF3‐ and P(O)‐tetrasubstituted carbon center. [ABSTRACT FROM AUTHOR]

Background: Aberrant proliferation of vascular smooth muscle cells (VSMCs) is the cause of neointima formation followed by vascular injury. Autophagy is involved in this pathological process, but its function is controversial. Recently, we found that methyltransferase like 3 (METTL3) inhibited VSMC proliferation by activating autophagosome formation. Moreover, we also demonstrated that METTL3 reduced the levels of phosphorylated mammalian target of rapamycin (p-mTOR) and cyclin dependent kinase 1 (p-CDK1/CDC2), which were critical for autophagy and proliferation regulation. However, whether mTOR and CDK1 mediated the function of METTL3 on autophagy and proliferation in VSMCs remains unknown. Results: We showed that the activator of mTOR, MHY1485 largely reversed the effects of METTL3 overexpression on VSMC autophagy and proliferation. Rapamycin, the inhibitor of mTOR, obviously nullified the pro-proliferation effects of METTL3 knockdown by activating autophagy in VSMCs. Unexpectedly, mTOR did not contribute to the impacts of METTL3 on migration and phenotypic switching of VSMCs. On the other hand, by knockdown of CDK1 in VSMC with METTL3 deficiency, we demonstrated that CDK1 was involved in METTL3-regulated proliferation of VSMCs, but this effect was not mediated by autophagy. Conclusions: We concluded that mTOR but not CDK1 mediated the role of METTL3 on VSMC proliferation and autophagy. [ABSTRACT FROM AUTHOR]

Objective A ferroptosis-related prognostic model for skin melanoma was constructed based on the TCGA database to reveal the relationship between ferroptosis and the prognosis of skin melanoma. Methods The ferroptosis-related genes were obtained from the KEGG database, and the data of skin melanoma were obtained from the TCGA database. The R package was used to obtain the clinical information of the corresponding samples from the TCGA database. Univariate Cox regression analysis was used to screen prognosis-related genes. Lasso regression was used for further variable selection, and the prognostic model was constructed based on the ggrisk package. The survival and the survminer packages were used to draw the survival curve. Results After removal of the overfitting genes, 12 prognosis-related ferroptosis genes were identified. Seven out of the 12 ferroptosis-related genes, including N0X4, VDAC2, P0R, CHMP5, GCHl, CP, and AC-SL4, were finally used to construct prognostic model. Survival analysis showed that the survival time of patients at the high-risk was significantly shorter than that at the low-risk (P <0. 05). Conclusions This prognostic model demonstrates the relationship between ferroptosis and the prognosis of cutaneous melanoma, providing a new direction for research in the treatment of cutaneous melanoma and the improvement of its prognosis. [ABSTRACT FROM AUTHOR]

Histone methylation is a complicate and dynamic epigenetic modification that regulates gene transcription, chromosomal structure and cell differentiation. Here, we discovered the interaction between the H3K4 demethylase, lysine specific demethylase 1 (LSD1, an important component of CoREST repressor complex) and the H3K27 methyltransferase, enhancer of zeste homolog 2 (EZH2, an essential component of PRC2). Immuno-precipitation and GST-pull down assay were performed to observe the interaction between the proteins. The MCF-7 cells were cultured and transfected with the siRNA. The mRNA and proteins were examined by using the real-time polymerase chain reaction (RT-PCR) and western blot assay, respectively. HPLC and LC–MS/MS analysis were performed to purify the proteins. RT-PCR-based quantitative ChIP analysis were performed. LSD1 interacts with histone modification protein EZH2 in MCF-7 cells. LSD1 and EZH2 target a few common genes. LSD1 knockdown and EZH2 knockdown affect protein expression. LSD1 knockdown and EZH2 knockdown affect the proteins involving in IFN signaling pathway. LSD1 and EZH2 modify histone methylation at IRF9 gene locus. We systematically analyzed the proteins that are affected by either LSD1 or EZH2 knockdown with proteomic approaches and identified that the interferon pathway and some other pathways are commonly affected. The interaction between LSD1 and EZH2 stabilizes the binding of LSD1 to the promoter region of IRF9, which is a key transcription factor of the interferon pathway. In conclusion, our study revealed that the coordination between histone demethylases and methyl-transferases might serve as a double lock system to suppress the expression of interferon stimulated genes. [ABSTRACT FROM AUTHOR]

Wearable robots have been growing exponentially during the past years and it is crucial to quantify the performance effectiveness and to convert them into practical benchmarks. Although there exist some common metrics such as metabolic cost, many other characteristics still needs to be presented and demonstrated. In this study, we developed an integrated evaluation (IE) approach of wearable exoskeletons of lower limb focusing on human performance augmentation. We proposed a novel classification of trial tasks closely related to exoskeleton functions, which were divided into three categories, namely, basic trial at the preliminary phase, semi-reality trial at the intermediate phase, and reality trial at the advanced phase. In the present study, the IE approach has been exercised with a subject who wore an active power-assisted knee (APAK) exoskeleton with three types of trial tasks, including walking on a treadmill at a certain angle, walking up and down on three-step stairs, and ascending in 11-storey stairs. Three wearable conditions were carried out in each trial task, i.e. with unpowered exoskeleton, with powered exoskeleton, and without the exoskeleton. Nine performance indicators (PIs) for evaluating performance effectiveness were adopted basing on three aspects of goal-level, task-based kinematics, and human–robot interactions. Results indicated that compared with other conditions, the powered APAK exoskeleton make generally lesser heart rate (HR), Metabolic equivalent (METs), biceps femoris (BF) and rectus femoris (RF) muscles activation of the subject at the preliminary phase and intermediate phase, however, with minimal performance augmentation at advanced phase, suggesting that the APAK exoskeleton is not suitable for marketing and should be further improved. In the future, continuous iterative optimization for the IE approach may help the robot community to attain a comprehensive benchmarking methodology for robot-assisted locomotion more efficiently. [ABSTRACT FROM AUTHOR]

Cell adhesion and migration are basic physiological processes in living organisms. Cells can actively probe their mechanical micro-environment and respond to the external stimuli through cell adhesion. Cells need to move to the targeting place to perform function via cell migration. For adherent cells, cell migration is mediated by cell-matrix adhesion and cell-cell adhesion. Experimental approaches, especially at early stage of investigation, are indispensable to studies of cell mechanics when even qualitative behaviors of cell as well as fundamental factors in cell behaviors are unclear. Currently, there is increasingly accumulation of experimental data of measurement, thus a quantitative formulation of cell behaviors and the relationship among these fundamental factors are highly needed. This quantitative understanding should be crucial to tissue engineering and biomedical engineering when people want to accurately regulate or control cell behaviors from single cell level to tissue level. In this review, we will elaborate recent advances in the experimental and theoretical studies on cell adhesion and migration, with particular focuses laid on recent advances in experimental techniques and theoretical modeling, through which challenging problems in the cell mechanics are suggested. [ABSTRACT FROM AUTHOR]

Abstract: The fluid flow in the lacunar–canalicular system of bone is an essential mechanical stimulation on the osteocyte networks. Due to the complexity of human physical activities, the fluid shear stress on osteocyte bodies and processes consists of both steady and oscillatory components. In this study, we investigated and compared the intracellular calcium ([Ca2+]i) responses of osteocytic networks under steady and oscillatory fluid flows. An in vitro osteocytic network was built with MLO-Y4 osteocyte-like cells using micro-patterning techniques to simulate the in vivo orderly organization of osteocyte networks. Sinusoidal oscillating fluid flow or unidirectional steady flow was applied on the cell surface with 2Pa peak shear stress. It was found that the osteocytic networks were significantly more responsive to steady flow than to oscillatory flow. The osteocytes can release more calcium peaks with higher magnitudes at a faster speed under steady flow stimulation. The [Ca2+]i signaling transients under the steady and oscillatory flows have significantly different spatiotemporal characters, but a similar responsive percentage of cells. Further signaling pathway studies using inhibitors showed that endoplasmic reticulum (ER) calcium store, extracellular calcium source, ATP, PGE2 and NO related pathways play similar roles in the [Ca2+]i signaling of osteocytes under either steady or oscillating flow. The spatiotemporal characteristics of [Ca2+]i transients under oscillating fluid flow are affected more profoundly by pharmacological treatments than under the steady flow. Our findings support the hypothesis that the [Ca2+]i responses of osteocytic networks are significantly dependent on the profiles of fluid flow. [Copyright &y& Elsevier]

As an important branch of biomedical engineering, respiratory mechanics helps to understand the physiology of the respiratory system and provides fundamental data for developing such clinical technologies as ventilators. To solve different clinical problems, researchers have developed numerous models at various scales that describe biological and mechanical properties of the respiratory system. During the past decade, benefiting from the continuous accumulation of clinical data and the dramatic progress of biomedical technologies (e.g. biomedical imaging), the theoretical modeling of respiratory mechanics has made remarkable progress regarding the macroscopic properties of the respiratory process, complexities of the respiratory system, gas exchange within the lungs, and the coupling interaction between lung and heart. The present paper reviews the advances in the above fields and proposes potential future projects. [ABSTRACT FROM AUTHOR]

Dentin constitutes the major part of human tooth. It is composed of a large number of tubules with both variational radii and radially parallel pattern. In addition, peritubular dentin surrounds each tubule lumen and has a higher elastic modulus than the matrix of dentin, i.e. intertubular dentin. Considering the above microstructural characteristics, a micromechanics model is used in this paper to evaluate the overall elastic properties of dentin. Five independent effective elastic parameters in transverse isotropic elasticity matrix can be expressed analytically by the material parameters of peri- and intertubular dentin and the volume fraction of tubules. To determine the effectivity of this theoretical model, a finite element (FE) model simulating a longitudinal tooth slice in moiré fringe testing of Wang and Weiner (J. Biomech. 31 (1998) 135) was performed. Furthermore, the FE model was developed incorporate modeling of variation of tubule''s diameter and softer characteristic of intertubular dentin near the dentin–enamel junction and around the pulp chamber. It turned out that the isoline figure of longitudinal displacement by FE calculation has very similar patterns to the moiré fringe results. However, the FE results of displacement by traditional stress–strain models which regard dentin as a homogeneous and isotropic material show an obviously different strain distributions as compared to published moiré fringes results. Thus the inhomogeneous and anisotropic model developed in this paper more accurately reflects the true physical nature of human dentin. [Copyright &y& Elsevier]

Previous studies have shown that ferroptosis of vascular smooth muscle cells (VSMCs) is involved in the development of aortic dissection (AD) and that histone methylation regulates this process. SP2509 acts as a specific inhibitor of lysine-specific demethylase 1 (LSD1), which governs a variety of biological processes. However, the effect of SP2509 on VSMC ferroptosis and AD remains to be elucidated. This aim of this study was to investigate the role and underlying mechanism of SP2509-mediated histone methylation on VSMC ferroptosis. Here, a mouse model of AD was established, and significantly reduced levels of H3K4me1 and H3K4me2 (target of SP2509) were found in the aortas of AD mice. In VSMCs, SP2509 treatment led to a dose-dependent increase in H3K4me2 levels. Furthermore, we found that SP2509 provided equivalent protection to ferrostatin-1 against VSMC ferroptosis, as evidenced by increased cell viability, decreased cell death and lipid peroxidation. RNA-sequencing analysis and subsequent experiments revealed that SP2509 counteracted cystine deficiency-induced response to inflammation and oxidative stress. More importantly, we demonstrated that SP2509 inhibited the expression of TFR and ferritin to reduce intracellular iron levels, thereby effectively blocking the process of ferroptosis. Therefore, our findings indicate that SP2509 protects VSMCs from multiple stimulus-induced ferroptosis by reducing intracellular iron levels, thereby preventing lipid peroxidation and cell death. These findings suggest that SP2509 may be a promising drug to alleviate AD by reducing iron deposition and VSMC ferroptosis. [Display omitted] • H3K4me1 and H3K4me2 levels were significantly reduced in mouse aortic dissection tissues. • SP2509 could inhibit CD- and IKE-induced ferroptosis by reducing inflammation and oxidative stress. • SP2509 could alleviate intracellular Fe2+ accumulation, thus preventing oxidative stress and ferroptosis. [ABSTRACT FROM AUTHOR]

AbstractTrabeculae bone undergoes directional growth along the applied force under physiological loading. The growth of bone structure relies on the coordinated interplay among osteocytes, osteoblasts, and osteoclasts. Under normal circumstances, bone remodeling maintains a state of equilibrium. Excessive bone formation can lead to osteosclerosis, while excessive bone resorption can result in osteoporosis and osteonecrosis. The investigation of the structural characteristics of trabeculae and the mechanotransduction between bone cells plays a vital role in the treatment of bone-related diseases. In this study, a fluid-solid coupling model of the entire vertebral bone was established based on micro-CT images obtained from rat tail vertebrae subjected to tensile loading experiments. The flow characteristics of bone marrow and the mechanical response of osteocytes in different regions under physiological loading were investigated. The results revealed a U-shaped distribution of wall fluid shear stress (FSS) along the longitudinal axis in trabecular bone, with higher FSS regions exhibiting greater mechanical stimulation on osteocytes. These findings elucidate a positive correlation between the mechanical microenvironment among osteocytes, osteoblasts, and osteoclasts, providing potential strategies for the prevention and treatment of bone diseases. [ABSTRACT FROM AUTHOR]

Cross-country sit-skiers use double poling (DP) technique to drive the slide. The aim of this study is to analyze how poling camber angle affect the capacity of power output and biomechanical parameters of the DP process. Twenty-four non-disabled college students (24.67 ± 1.46 years old) were recruited to perform three successive 30-s maximal effort tests with different poling camber angles of 0°, 15°, 24° and 30° using a sit-skiing ergometer. The biomechanical parameters, output power and muscle activation of the subjects were analyzed. The results showed that DP output power increased with the increase of poling camber angle at 15° (597.78 ± 150.31 J), 24° (610.94 ± 158.96 J, P = 0.011) and 30° (629.10 ± 168.78 J, P < 0.001) compared with 0° (590.65 ± 148.95 J). However, effective output power decreased with the increase of camber angle. Poling with camber angle of 24° had the shortest cycle time 1.53 ± 0.17 s, compared with other abduction angle (0°, 1.57 ± 0.19 s, 15°, 1.55 ± 0.16 s, and 30°, 1.56 ± 0.19 s). Compared with 0° (1.02 ± 0.14 m), the cycle distance significantly increased at poling camber angles of 24° (1.07 ± 0.12 m, P = 0.029) and 30° (1.11 ± 0.13 m, P < 0.001). With the increase of poling camber angle, the shoulder and elbow joint range of motions and joint moments were significantly increased. This study found that poling with shoulder abducted increased the output power but decreased the efficiency. By analyzing the poling angle and poling force, we find that the optimal poling camber angle may depend on the terrain or the skiing speed. These results may guide the competition techniques and tactics in the matches, and may further influence the strength-training programs of cross-country sit-skiing athletes. [ABSTRACT FROM AUTHOR]

Background: E1A-associated 300-kDa protein (P300), an endogenous histone acetyltransferase, contributes to modifications of the chromatin landscape of genes involved in multiple cardiovascular diseases. Ferroptosis of vascular smooth muscle cells (VSMCs) is a novel pathological mechanism of aortic dissection. However, whether P300 regulates VSMC ferroptosis remains unknown. Methods: Cystine deprivation (CD) and imidazole ketone erastin (IKE) were used to induce VSMC ferroptosis. Two different knockdown plasmids targeting P300 and A-485 (a specific inhibitor of P300) were used to investigate the function of P300 in the ferroptosis of human aortic smooth muscle cells (HASMCs). Cell counting kit-8, lactate dehydrogenase and flow cytometry with propidium iodide staining were performed to assess the cell viability and death under the treatment of CD and IKE. BODIPY-C11 assay, immunofluorescence staining of 4-hydroxynonenal and malondialdehyde assay were conducted to detect the level of lipid peroxidation. Furthermore, co-immunoprecipitation was utilized to explore the interaction between P300 and HIF-1α, HIF-1α and P53. Results: Compared with normal control, the protein level of P300 was significantly decreased in HASMCs treated with CD and IKE, which was largely nullified by the ferroptosis inhibitor ferrostatin-1 but not by the autophagy inhibitor or apoptosis inhibitor. Knockdown of P300 by short-hairpin RNA or inhibition of P300 activity by A-485 promoted CD- and IKE-induced HASMC ferroptosis, as evidenced by a reduction in cell viability and aggravation of lipid peroxidation of HASMCs. Furthermore, we found that hypoxia-inducible factor-1α (HIF-1α)/heme oxygenase 1 (HMOX1) pathway was responsible for the impacts of P300 on ferroptosis of HASMCs. The results of co-immunoprecipitation demonstrated that P300 and P53 competitively bound HIF-1α to regulate the expression of HMOX1. Under normal conditions, P300 interacted with HIF-1α to inhibit HMOX1 expression, while reduced expression of P300 induced by ferroptosis inducers would favor HIF-1α binding to P53 to trigger HMOX1 overexpression. Furthermore, the aggravated effects of P300 knockdown on HASMC ferroptosis were largely nullified by HIF-1α knockdown or the HIF-1α inhibitor BAY87-2243. Conclusion: Thus, our results revealed that P300 deficiency or inactivation facilitated CD- and IKE-induced VSMC ferroptosis by activating the HIF-1α/HMOX1 axis, which may contribute to the development of diseases related to VSMC ferroptosis. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to investigate the changes in oocytes at the transcriptome level after applying continuous microvibrational mechanical stimulation to human immature oocytes during in vitro maturation. Methods: The discarded germinal-vesicle stage (GV) oocytes with no fertilization value after oocytes retrieval in assisted reproduction cycles were collected. Part of them was stimulated with vibration (n = 6) at 10 Hz for 24 h after obtaining informed consent; the other was cultured in static condition (n = 6). Single-cell transcriptome sequencing was used to detect the differences in oocyte transcriptome compared with the static culture group. Results: The applied 10-Hz continuous microvibrational stimulation altered the expression of 352 genes compared with the static culture. Gene Ontology (GO) analysis suggested that the altered genes were mainly enriched with 31 biological processes. The mechanical stimulation upregulated 155 of these genes and downregulated 197 genes. Among them, the genes related to mechanical signaling, such as protein localization to intercellular adhesion (DSP and DLG-5) and cytoskeleton (DSP, FGD6, DNAJC7, KRT16, KLHL1, HSPB1, MAP2K6), were detected. DLG-5, which was related to protein localization to intercellular adhesion, was selected for immunofluorescence experiments based on the transcriptome sequencing results. The protein expression of DLG-5 in the microvibration-stimulated oocytes was higher than that in the static culture oocytes. Conclusions: Mechanical stimulation affects the transcriptome during oocyte maturation, causing the express changes in intercellular adhesion and cytoskeleton-related genes. We speculate that the mechanical signal may be transmitted to the cell through DLG-5 protein and cytoskeleton-related protein to regulate cellular activities. [ABSTRACT FROM AUTHOR]

Background: Products from Ficus carica have been used in traditional medicine to treat many diseases. This study aimed to analyze anticancer effects of extracts of F. carica leaves on the triple-negative breast cancer cell line MDA-MB-231. Materials and methods: The human breast cancer cell line MDA-MB-231 was used to evaluate effects of F. carica extracts. Effects of F. carica on cell viability were evaluated using MTT assays. Cell-cycle distribution was examined using cell-cycle analysis. Wound-healing assays were used to evaluate migration of MDA-MB-231. Quantitative reverse-transcription polymerase chain reaction was used to detect levels of Bax, p53, p21, GATA3, ELF5, cyclin-dependent kinases, MMP2, and tissue inhibitors of metalloproteinase. Results: We investigated the mechanism of anti-growth effects, and found that the expressions of genes that promote apoptosis were increased. In addition, the treated cells illustrated increased portion at S phase and changed expression of cyclin-dependent kinases, demonstrating cell-cycle arrest at the S phase. Furthermore, treated cells showed decreased cell mobility, which is essential for metastasis. Two of the active components of F. carica leaves, bergapten and psoralen, had similar anticancer effects as F. carica leaf extracts, indicating that these two components might play important roles in anticancer effects of F. carica leaves. Conclusion: Our findings suggest that F. carica leaves might be a good source to develop drugs for suppressing cancer-cell growth and migration to treat triple-negative breast cancers. [ABSTRACT FROM AUTHOR]

Prevention of neointima formation is the key to improving long‐term outcomes after stenting or coronary artery bypass grafting. RNA N6‐methyladenosine (m6A) methylation has been reported to be involved in the development of various cardiovascular diseases, but whether it has a regulatory effect on neointima formation is unknown. Herein, we revealed that methyltransferase‐like 3 (METTL3), the major methyltransferase of m6A methylation, was downregulated during vascular smooth muscle cell (VSMC) proliferation and neointima formation. Knockdown of METTL3 facilitated, while overexpression of METTL3 suppressed the proliferation of human aortic smooth muscle cells (HASMCs) by arresting HASMCs at G2/M checkpoint and the phosphorylation of CDC2 (p‐CDC2) was inactivated by METTL3. On the other hand, the migration and synthetic phenotype of HASMCs were enhanced by METTL3 knockdown, but inhibited by METTL3 overexpression. The protein levels of matrix metalloproteinase 2 (MMP2), MMP7 and MMP9 were reduced, while the expression level of tissue inhibitor of metalloproteinase 3 was increased in HASMCs with METTL3 overexpression. Moreover, METTL3 promoted the autophagosome formation by upregulating the expression of ATG5 (autophagy‐related 5) and ATG7. Knockdown of either ATG5 or ATG7 largely reversed the regulatory effects of METTL3 overexpression on phenotypic switching of HASMCs, as evidenced by increased proliferation and migration, and predisposed to synthetic phenotype. These results indicate that METTL3 inhibits the phenotypic switching of VSMCs by positively regulating ATG5‐mediated and ATG7‐mediated autophagosome formation. Thus, enhancing the level of RNA m6A or the formation of autophagosomes is the promising strategy to delay neointima formation. [ABSTRACT FROM AUTHOR]

The subacromial impingement syndrome is a high-incidence injury for cross-country sit-skiing skier, which is often accompanied by muscle imbalance. However, at present, no musculoskeletal model has been identified for this sport. Thus, this research aimed to establish a bilateral upper extremity trunk (BUET) musculoskeletal model suitable for cross-country sit-skiing based on OpenSim software and verify the function of the model. By splicing three existing OpenSim models, an upper limb model with 17 segments, 35 degrees of freedom, and 472 musculotendon actuators was established. The clavicle and scapula were modeled as individual bodies and then connected to the torso through a three-degrees-of-freedom rotational joint and to the clavicle through a weld joint, respectively. The five lumbar vertebrae were established separately and coupled into a three-degree-of-freedom joint. Kinematics, kinetic, and EMG signal data of five 15-s maximal effort interval tests were obtained by using seven cameras, ergometers, and surface EMG synchronous collection. Based on the resulting rotator cuff muscle geometry of the model, simulated muscle activation patterns were comparable to experimental data, and muscle-driven ability was proven. The model will be available online (https://simtk.org/projects/bit) for researchers to study the muscle activation of shoulder joint movement. [ABSTRACT FROM AUTHOR]

A label free and easy-to-prepare optical sensor with high mechanical strength for the fast and visible response to tension and pH variables was reported. An elastic nanocomposite hydrogel was successfully fabricated by in situ free-radical co-polymerization of N , N -dimethylacrylamide (DMAA), acrylic acid (AA) and aluminum oxide nanoparticles (Al 2 O 3 NPs). DMAA and AA could form effective cross-linkage with Al 2 O 3 NPs via hydrogen binding, electrostatic interaction and bidentate bridging. By encapsulating polymethyl methacrylate (PMMA) colloidal arrays into the hydrogels, the optical nanocomposite hydrogels (ONHs) can be easily obtained. This three-dimensionally ordered array exhibits a stop band, and the optical hydrogels can tune the bright color from blue to cyan, green, yellow green, yellow, orange and then finally red by mechanical stimulation of uniaxial tension within 50% strain following Bragg’s law. The mechanical and optical properties can be adjusted via changing the fraction of AA and polymerization time. Meanwhile, the mechanical and optical responses were reversible for more than 10 times without deterioration. Besides, this material has rapid response to the changing of pH and the full-color change was observed. Owing to the high biocompatibility of nanocomposite hydrogel (NC gel) system and the excellent mechanical strength and water-stability of these ONHs, this optical sensor has high potential to be applied in biomedical field as tension or pH sensor for the intraocular pressure measurement and tonometry and blood gas analysis. [ABSTRACT FROM AUTHOR]

Mechanical loading, such as fluid shear stress (FSS), is regarded as the main factor that regulates the biological responses of bone cells. Our previous studies have demonstrated that the RAW264.7 osteoclast precursors migrate toward the low-FSS region under the gradient FSS field by a cone-and-plate flow chamber, in which the FSS in the outer region is larger than that in the inner region along the radial direction. Whether the FSS distribution on a cell depends on the gradient direction of FSS field should be clarified to explain this experimental observation. In this study, the finite element models of the discretely distributed or closely packed cells adherent on the bottom plate in a cone-and-plate flow chamber were constructed, and cells were regarded as compressible isotropic Hookean solid. Results showed that the average FSS of each discretely distributed cell at the quarter sector far from the center (SFC) was about 0.1% greater than that at the quarter sector near the center (SNC). In the bands with different orientations for a cell, the relative difference between the average FSS in the SFC and the SNC becomes smaller with increased band height. For the hexagonal closely packed cells, the relative value of SFC and SNC increases with increasing cell spacing. The difference between the local wall FSS in the SFC and the SNC may activate mechanosensitive ion channels and further regulate the migration of osteoclast precursors toward the low-FSS region under the gradient FSS field. [ABSTRACT FROM AUTHOR]

Silk protein builds one of the strongest natural fibers based on its complex nanocomposite structures. However, the mechanical performance of silk protein, related to its molecular structure and packing is still elusive. In this study, we constructed an atomistic silk protein network model, which reproduces the extensive connection topology of silk protein with structure details of the β-sheet crystallites and amorphous domains. With the silk protein network model, we investigated the structure evolution and stress distribution of silk protein under external loading. We found a pre-stretching treatment during the spinning process can improve the strength of silk protein. This treatment improves the properties of silk protein network, i.e., increases the number of nodes and bridges, makes the nodes distributed homogeneously, and induces the bridges in the network well aligned to the loading direction, which is of great benefit to the mechanical performances of silk protein. Our study not only provides a realized atomistic model for silk protein network that well represents the structures and deformations of silk proteins under loading, but also gains deep insights into the mechanism how the pre-loading on silk proteins during spinning improves the mechanical properties of silk fibers. [ABSTRACT FROM AUTHOR]

The adhesion morphology of a cell monolayer results in a mechanical force inside cells, between cells, or between cells and substrates. The mechanical force regulates the differentiation of stem cells, but its influence on cell fusion is seldom studied. The present study is focused on osteoclast precursors, RAW264.7 monocytes, which can fuse into multinucleated cells (MNCs) responsible for bone resorption. Cells were cultured on circular and ring-like patterned substrates. Then, cell fusion, cell–substrate traction force, and force-sensitive molecules in different regions were measured and analyzed. Results showed that MNCs mainly appeared in the interior of the ring-like pattern and the central zone of the circular pattern, where both cell–substrate traction force and in-plane maximal shear stress were smaller than that at the patterns' edge. The immunostaining results revealed that F-actin, vinculin, β-catenin, and E-cadherin were highly distributed at the edge of patterns. High seeding density of cells promoted mechanical force-dependent fusion. When calcium-dependent cell–cell connections were inhibited by E-cadherin antibody or low-calcium medium, the fusion into MNCs was greatly reduced. Thus, the morphology of cell monolayer decides the mechanical state of cell–substrate interaction and cell–cell connection, ultimately regulating the fusion of osteoclast precursors. [ABSTRACT FROM AUTHOR]

The skeleton can adapt to mechanical loading through bone remodeling, and osteoclasts close to microdamages are believed to initiate bone resorption. However, whether local mechanical loading, such as fluid flow, regulates recruitment and differentiation of osteoclast precursors at the site of bone resorption has yet to be investigated. In the present study, finite element analysis first revealed the existence of a low-fluid shear stress (FSS) field inside microdamage. Based on a custom-made device of cone-and-plate fluid chamber, finite element analysis and particle image velocimetry measurement were performed to verify the formation of gradient FSS flow field. Furthermore, the effects of gradient FSS on the migration, aggregation, and fusion of osteoclast precursors were observed. Osteoclast precursor RAW264.7 cells migrated along a radial direction toward the region with decreased FSS during exposure to gradient FSS stimulation for 40 min, thereby deviating from the direction of actual fluid flow indicated by fluorescent particles. When calcium signaling pathway was inhibited by gadolinium and thapsigargin, cell migration toward a low-FSS region was significantly reduced. For the other cell lines MC3T3-E1, PDLF, rat mesenchymal stem cells, and Madin-Darby canine kidney epithelial cells, gradient FSS stimulation did not lead to low-FSS inclined migration. After being cultured under gradient FSS stimulation for 6 days, RAW264.7 cells showed significantly higher density and ratio of TRAP-positive multinucleated osteoclasts in the low-FSS region to those in the high-FSS region. Therefore, osteoclast precursor cells may exhibit the special ability to sense FSS gradient and tend to actively migrate toward low-FSS regions, which are regulated by calcium signaling pathway. [ABSTRACT FROM AUTHOR]

It was found that preosteoblast MC3T3-E1 cells were less responsive in calcium signaling than mature osteocyte MLO-Y4 cells when a steady fluid flow was exerted on a micropatterned cell network. However, the effect of fluid flow on the calcium response in preosteocyte MLO-A5 was seldom investigated. In the present study, MLO-A5 as well as MC3T3-E1 and MLO-Y4 cells were cultured on a regular substrate with high or low density under unidirectional or oscillatory fluid flow. The results showed that calcium oscillation in the cells during late osteogenesis was significantly stronger than during early osteogenesis regardless of the fluid flow type or the presence of a physical cell–cell connection. Calcium oscillation produced by the oscillatory flow in the three types of cells was stronger than that produced by the unidirectional flow, but MC3T3-E1 and MLO-A5 cells exhibited limited potential for calcium oscillation compared with MLO-Y4 cells. After suramin was used to block the binding of extracellular adenosine triphosphate (ATP) to the membrane P2 receptor, the calcium oscillation in the three types of bone cells with or without physical connections was significantly suppressed as a single responsive peak under unidirectional flow. For the ATP-blocking group of low-density cells under oscillatory flow, the number of oscillation peaks in three types of cells was still more than two. It indicates that besides the ATP pathway, other mechanosensitive calcium pathways may exist under oscillatory flow. The present study provided further evidence for the osteogenic stage-dependent calcium response of bone cells under unidirectional or oscillatory fluid flow. [ABSTRACT FROM AUTHOR]

ABSTRACT Periodontal ligament (PDL) fibroblasts play an important role in preserving periodontal homeostasis and transmitting mechanical signals to alveolar bone. Connexin 43 (Cx43), a gap junction protein, is essential for bone homeostasis and regulates bone remodeling. However, the function of Cx43 in human PDL fibroblast-regulated bone remodeling has not yet been elucidated. In this study, human PDL fibroblasts were exposed to cyclic mechanical tension with a maximum 5% elongation for different durations. We then examined the expression of signaling molecules related to osteogenesis and osteoclastogenesis at both the mRNA and protein levels as well as the activity of extracellular signal-regulated kinase (ERK) in human PDL fibroblasts after loading. We found that mechanical tension increased Cx43, which further upregulated osteogenic (e.g., RUNX2, Osterix, and OPG) and down-regulated osteoclastogenic (e.g., RANKL) signaling molecules. Suppressing Cx43 gene ( Gja1) by siRNA inhibited the increase in osteogenesis-related molecules but enhanced RANKL expression. Similar to Cx43, activated ERK1/2 was also enhanced by mechanical tension and suppressed by Cx43 siRNA. Inhibition of ERK1/2 signaling using PD98059 reduced the tension-regulated increase in osteogenesis-related molecules but enhanced that of osteoclastogenesis-related ones. These findings suggest that cyclic tension may involve into the osteogenic or osteoclastogenetic differentiation potential of human PDL fibroblasts via the Cx43-ERK1/2 signaling pathway. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1008-1014, 2015. [ABSTRACT FROM AUTHOR]

Osteoclasts are large multinucleate cells originating from the fusion of monocytes that are differentiated from hematopoietic stem cells. Although activated osteoclasts preferentially move to the area of microcrack by chemotaxis, whether such mechanical cues as fluid shear stress (FSS) regulate the migration of osteoclasts remains unknown. This study focuses on the effect of FSS on the migration of RAW264.7 monocytes and differentiated osteoclasts, as well as the roles of calcium signaling pathways in cell migration behaviors. We study five calcium signaling pathways, namely, mechanosensitive cation-selective channels (MSCC), phospholipase C, endoplasmic reticulum (ER), adenosine triphosphate, and extracellular calcium. Results show that FSS induces the migration of RAW264.7 cells along flow direction, and the directionality, alignment along the flow direction, and speed of cells are significantly enhanced with the increase in FSS levels. Blocking the pathways of MSCC, ER, or extracellular calcium significantly reduces the migration of RAW264.7 cells along the flow direction. However, the inhibition of calcium signaling pathways does not affect the migration behaviors after inducing RAW264.7 cells for 4 or 8 days with the conditioned medium, Therefore, this study indicates that both undifferentiated monocytes and differentiated osteoclasts tend to migrate along flow direction, furthermore the FSS-induced directional migration of the monocytes is regulated by calcium signaling pathways, but that of differentiated osteoclasts is unaffected. [ABSTRACT FROM AUTHOR]

The differentiation of vascular smooth muscle cells (VSMCs), which are exposed to mechanical stretch in vivo , plays an important role in vascular remodeling during hypertension. Here, we demonstrated the mechanobiological roles of large conductance calcium and voltage-activated potassium (BK) channels in this process. In comparison with 5% stretch (physiological), 15% stretch (pathological) induced the de-differentiation of VSMCs, resulting in significantly decreased expressions of VSMC markers, i.e. , α-actin, calponin and SM22. The activity of BK channels, assessed by patch clamp recording, was significantly increased by 15% stretch and was accompanied by an increased alternative splicing of BK channel α-subunit at the stress axis-regulated exons (STREX). Furthermore, transfection of whole BK or STREX-deleted BK plasmids revealed that STREX was important for BK channels to sense mechanical stretch. Using thapsigargin (TG) which induces endoplasmic reticulum (ER) stress, and xbp1-targeted siRNA transfection which blocks ER stress, the results revealed that ER stress was contribute to stretch-induced alternative splicing of STREX. Our results suggested that during hypertension, pathological stretch may induce the ER stress in VSMCs, which affects the alternative splicing and activity of BK channels, and subsequently modulates VSMC differentiation. [ABSTRACT FROM AUTHOR]

ABSTRACT Connexin 43 (Cx43), a gap junctional protein, regulates osteocyte viability, and modulates mechanical stimulation-induced bone remodeling. However, the underlying mechanisms of its action remain unclear. In the current study, osteocyte-like MLO-Y4 cells were exposed to fluid shear stress (FSS) of 16 (physiological) or 30 (high) dyne/cm2 for the indicated time points. Cx43 gene ( Gja1) was silenced using siRNA or the protein was blocked chemically. The signaling molecules related to osteocyte apoptosis, osteogenesis, or osteoclastogenesis were detected at mRNA or protein levels. The results showed that physiological FSS significantly upregulated Cx43, which further inhibited apoptosis pathways (e.g., caspase-3) and osteoclastogenesis signaling (e.g., RANKL), but activated osteogenesis signaling (Sost/sclerostin). Suppressing Cx43 gene ( Gja1) by siRNA or chemically blocking gap junction communication enhanced caspase-3, RANKL, and Sost/sclerostin, which could be restored with physiological FSS over 8 h. In addition, high FSS decreased Cx43 expression and adversely affected signaling molecules compared with physiological FSS. The findings indicate the involvement of Cx43 in mechanotransduction of FSS and in the modulation of mechanical loading-related apoptosis, osteogenesis, and osteoclastogenesis of osteocytes. This may provide a cellular and molecular basis for interpreting the biomechanical mechanism of bone absorption and remodeling. © 2013 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 31:1959-1965, 2013 [ABSTRACT FROM AUTHOR]

Keratinocyte migration during re-epithelization is crucial in wound healing under biochemical and biomechanical microenvironment. However, little is known about the underlying mechanisms whereby mechanical tension and cocultured fibroblasts or keratinocytes modulate the migration of keratinocytes or fibroblasts. Here we applied a tensile device together with a modified transwell assay to determine the lateral and transmembrane migration dynamics of human HaCaT keratinocytes or HF fibroblasts. A novel pattern of asymmetric migration was observed for keratinocytes when they were cocultured with non-contact fibroblasts, i.e., the accumulative distance of HaCaT cells was significantly higher when moving away from HF cells or migrating from down to up cross the membrane than that when moving close to HF cells or when migrating from up to down, whereas HF migration was symmetric. This asymmetric migration was mainly regulated by EGF derived from fibroblasts, but not transforming growth factor α or β1 production. Mechanical stretch subjected to fibroblasts fostered keratinocyte asymmetric migration by increasing EGF secretion, while no role of mechanical stretch was found for EGF secretion by keratinocytes. These results provided a new insight into understanding the regulating mechanisms of two- or three-dimensional migration of keratinocytes or fibroblasts along or across dermis and epidermis under biomechanical microenvironment. [ABSTRACT FROM AUTHOR]

Biomechanical factors play an important role in tumor distribution, epithelial-mesenchymal transition (EMT), invasion and other important processes. Despite fewer reports investigating biomechanical function in papillary thyroid carcinoma (PTC), a large number of PTC cases are located close to the trachea and the majority of advanced cases of PTC have been associated with invasion of the trachea. However, the effect of trachea stiffness on PTC distribution and growth remains unknown. To clarify this issue, two types of PTC cells (TPC-1 and KTC-1) were seeded on a substrate with different stiffness to observe cell proliferation and movement. To identify the effect of trachea stiffness on the thyroid, two thyroid lobes (left and right) were evenly divided into interior (close to the trachea) and lateral (away from the trachea) parts, based on the vertical line between the trachea and thyroid lateral margin with different von Mises stress values. As PTC originates from papillary thyroid microcarcinoma (PTMC) with a maximum diameter of <1 cm, the present study selected PTMC as the study subject to reflect initial PTC distribution in the thyroid. The association between the percentage of PTMC distribution in different parts of the thyroid and von Mises stress values was analyzed. Both PTC cells exhibited stronger proliferation and mobility on the stiff substrate compared with that on the soft substrate. Furthermore, the results of finite element analysis revealed that the von Mises stress values of the interior parts of the trachea were notably higher compared with that in the lateral parts. PTMC distribution in the interior trachea was notably greater compared with that in the lateral section. There was also an observed association between von Mises stress values and PTMC distribution. In addition, the results of RNA-sequencing and reverse transcription-quantitative PCR demonstrated that three biomechanical genes were overexpressed in PTMC located in the interior section compared with that in adjacent normal tissue, and the related signaling pathways were also activated in these tissues. On the whole, these results indicated that trachea stiffness may supply a suitable biomechanical environment for PTMC growth, and the related biomechanical genes may serve as novel targets for PTMC diagnosis and prognostic estimation. [ABSTRACT FROM AUTHOR]

The structure of a bone tissue is capable of adapting to mechanical loading through the process of bone remodeling, which is regulated by osteoblasts and osteoclasts. Fluid flow within trabecular porosity under cyclic loading is one of the factors stimulating the biological response of osteoblasts and osteoclasts. However, the relation between loading directions and interstitial fluid flow was seldom studied. In the present study, a finite element model based on micro-computed tomographic reconstructions is built by using a mouse femur. Results from the fluid–solid coupling numerical simulation indicate that the loading in different directions generates a distinct distribution of von Mises stress in the bone matrix and a fluid shear stress (FSS) in the bone marrow. The loading along the physiological direction leads to a more uniform distribution of solid stress and produces an FSS level beneficial to the biological response of osteoblasts and osteoclasts compared with those along the non-physiological direction. There was a minimum threshold line of wall FSS with a specific solid stress at the bone surface, suggesting that the wall FSS is mainly induced by the solid strain. These results may offer fundamental data in understanding the mechanical environment around osteoblasts and osteoclasts and the cellular and molecular mechanisms of mechanical loading-induced bone remodeling. [ABSTRACT FROM AUTHOR]

There is ample evidence indicating that epicardial adipose tissue (EAT) volume and thickness is positively associated with coronary artery disease (CAD). However, the exact pathological changes in the human EAT after myocardial ischemia remains largely unclear. In the current study, we applied a comparative quantitative proteomics to elucidate the altered biological processes in the EAT of ischemic cardiomyopathy (ICM) patients. A total of 1649 proteins were successfully quantified in our study, among which 165 proteins were significantly changed (ratio <0.8 or >1.2 fold and p < 0.05 in both repetitions) in EAT of ICM individuals. Gene ontology (GO) enrichment analysis revealed that cardiac structure and cellular metabolism were over-represented among these regulated proteins. The hypertrophic cardiomyopathy, adrenergic signaling in cardiomyocytes, extracellular matrix (ECM)-receptor interaction, phagosome, Glycolysis/Gluconeogenesis, and PPAR signaling pathway were highlighted by the KEGG PATHWAY analysis. More importantly, we found that the proteins responsible for extracellular matrix organization were dramatically increased in EAT of ICM patients. In addition, the picrosirius red (PSR) staining results showed that the collagen fiber content was prominently increased, which indicated the EAT of ICM individuals underwent extracellular matrix remodeling and ERK1/2 activation maybe responsible for these pathological changes partially. [ABSTRACT FROM AUTHOR]