Traction Force Research Articles

Development of a Mathematical Model and Structural Optimization of the Specific Resistance of a Broken Line Subsoiler

Saline-alkali soil has the characteristics of high density, high firmness and poor permeability. Aiming at the problems of shallow subsoiling depth, large subsoiling specific resistance and small soil bulkiness in subsoiling operation in saline-alkali soil, this paper establishes a mathematical model of the specific resistance of a broken line subsoiler and uses genetic algorithm and the discrete element method to optimize the structure design of the subsoiler. Firstly, the mathematical model was developed by analyzing the force of the subsoiler in the working process. The genetic algorithm was used to solve the problem, and three geometric models of the broken line subsoilers were fitted. Then, EDEM software was used to simulate this, and the tillage performance was evaluated with draft force, soil disturbance area, subsoiling specific resistance and soil bulkiness as the indexes and verified by field experiment. The results showed that the subsoiling specific resistance of the three broken line subsoilers was significantly lower than that of the standard subsoiler in the simulation test. Compared to the standard subsoiler, the soil disturbance area of the broken line subsoiler-B increased by 12%, the draft force decreased by 19%, the subsoiling specific resistance decreased by 26% and the bulkiness increased by 6%. The field experiment results showed that the broken line subsoiler-B reduced the traction force and improved the tillage efficiency compared to the standard subsoiler, which was consistent with the analysis results of EDEM. The broken line subsoiler can effectively enhance the quality of cultivated land.

Dysfunctional mechanotransduction regulates the progression of PIK3CA-driven vascular malformations

Somatic activating mutations in PIK3CA are common drivers of vascular and lymphatic malformations. Despite common biophysical signatures of tissues susceptible to lesion formation, including compliant extracellular matrix and low rates of perfusion, lesions vary in clinical presentation from localized cystic dilatation to diffuse and infiltrative vascular dysplasia. The mechanisms driving the differences in disease severity and variability in clinical presentation and the role of the biophysical microenvironment in potentiating progression are poorly understood. Here, we investigate the role of hemodynamic forces and the biophysical microenvironment in the pathophysiology of vascular malformations (VMs), and we identify hemodynamic shear stress and defective endothelial cell mechanotransduction as key regulators of lesion progression. We found that constitutive PI3K activation impaired flow-mediated endothelial cell alignment and barrier function. We show that defective shear stress sensing in PIK3CAE542K endothelial cells is associated with reduced myosin light chain phosphorylation, junctional instability, and defective recruitment of vinculin to cell–cell junctions. Using three dimensional (3D) microfluidic models of the vasculature, we demonstrate that PIK3CAE542K microvessels apply reduced traction forces and are unaffected by flow interruption. We further found that draining transmural flow resulted in increased sprouting and invasion responses in PIK3CAE542K microvessels. Mechanistically, constitutive PI3K activation decreased cellular and nuclear elasticity resulting in defective cellular tensional homeostasis in endothelial cells which may underlie vascular dilation, tissue hyperplasia, and hypersprouting in PIK3CA-driven venous and lymphatic malformations. Together, these results suggest that defective nuclear mechanics, impaired cellular mechanotransduction, and maladaptive hemodynamic responses contribute to the development and progression of PIK3CA-driven vascular malformations.

Modeling and Analysis of the Turning Performance of an Articulated Tracked Vehicle That Considers the Inter-Unit Coupling Forces

The interactions between ground reaction forces and inter-unit coupling forces add complexity to the study of the turning motion of articulated tracked vehicles (ATVs). To accurately analyze the turning performance of an ATV, this study developed a steady-state steering model that captures the effects of load transfer caused by coupling and centrifugal forces. First, based on vehicle kinematics under skidding conditions, formulas that incorporate parameters for the lateral track displacement were derived to calculate the turning radii of the front and rear units. Then, the track traction forces and turning resistance moments were calculated using the shear stress–shear displacement relationship. Finally, a steady-state steering model on firm ground conditions was developed for the vehicle according to mechanical equilibrium conditions, and the model was validated using previously reported data. Analyses of the results revealed that the coupling forces provided the driving moments for the turning motion by the transfer of the centrifugal and ground reaction forces that acted on the front and rear units. During turning, the rear unit had a larger radius than the front unit, and the minimum swept radius of the ATV was dependent upon the radius of the outer track trajectory of the rear unit. Specifically, at a speed of 3.1 m/s and a steering angle of 35°, the vehicle exhibited a minimum outer swept radius of 8.8 m, requiring a turning space equivalent to a 3.1-meter-wide road. The required turning space increased as both the steering angle and speed increased.

Justification of the application of a distributed network of photoelectric converters to power a linear motor of magnetolevitation transport

Modern high-speed transport is the basis of sustainable economic and social development of the state, society in compliance with environmental requirements. The concept of power supply of a linear motor of magneto-levitation transport from a distributed network of photovoltaic converters is substantiated. The basic power element of a track power plant is proposed in the form of a completed unit consisting of a solar panel, a storage device and an inverter, which operates on a load in the form of a "short" track coil. The use of a "short" track coil allows reducing electrical energy losses, since the traction force is formed only in the zone of interaction with the rolling stock, energy is not transmitted to unused sections of the track structure. By reducing the length of the working section, other energy indicators of the system as a whole are significantly suspended, in particular the power factor and effi-ciency. Reducing the length of the working sections in conditions of high speeds of rolling stock will lead to increased requirements for reliability and speed of operation of track switches. The track switches are created on the basis of power semiconductor switches, which are controlled by modern microcontrollers. The effectiveness of the proposed structure de-pends on the solar activity in the region of the transport artery. The estimated solar activity indicators allow us to state that the weight indicators of the rolling stock that must move on the track with a "short" section correspond to the available resources.

THE BIOMECHANICAL STABILITY OF A NOVEL BIOABSORBABLE MAGNESIUM ALLOY (ZX00:Mg-Zn–Ca) BONE ANCHOR FOR ROTATOR CUFF REPAIRS: A HUMAN EX VIVO STUDY

Introduction: The purpose of this study was to ascertain the primary ex vivo biomechanical stability of a novel bioabsorbable magnesium alloy (ZX00: Mg–Zn–Ca) bone anchor in human cadaveric proximal humeri, indicated in the reconstruction of the rotator cuff. Methods: Twenty human Thiel-embalmed cadaveric humeri were prepared and freed from soft tissue. One [Formula: see text]5.7 × 20.5-mm ZX00 anchor and one [Formula: see text]5.5 mm × 16.3 mm Arthrex Titanium FT Corkscrew (ATC) control anchor were inserted into the footprint of the supraspinatus tendon, 15 mm apart. The humeri were mounted onto a material testing machine and following a 40 N preload, cyclic loading was performed over 400 cycles. If the construct remained intact, ultimate load to failure (ULTF) was measured using an increasing axial load of 1 mm/s, ULTF and mode of failure were recorded. Results: No difference was found in the ability to withstand cyclic loading, mode or load-to-failure strengths between ZX00 and control anchors. The maximum tractional force loaded for the ZX00 anchors had a median of 257.4 N (range 165.3–328.2). The corresponding value for the ATC anchors averaged 239.9 N (range 118.9–306.7). Conclusion: ZX00 alloy anchors appear to provide adequate initial biomechanical stability when compared to an industry-standard control in a cadaveric rotator cuff repair model.

Arrhythmic mitral valve prolapse: beyond valve geometry, traction forces quantification

Abstract Introduction Arrhythmic Mitral Valve Prolapse (AMVP) constitutes a subgroup of Mitral Valve Prolapse (MVP) patients who, without necessarily having significant insufficiency, exhibit an increased risk of malignant ventricular arrhythmias (VA). Although this entity has recently gained significant attention in the scientific community, its pathophysiology and phenotypic characterization remain not completely elucidated. It has been postulated that leaflet displacement increases tension on the papillary muscles (PM), causing excessive superior traction. This may serve as the trigger for VA and, over time, lead to localized myocardial remodeling and subsequent fibrosis at the level of PM and left ventricle (LV) basal inferolateral wall, which is seen in this population. We believe we can identify and quantify this mechanism using transthoracic echocardiography (TTE). Therefore, we could define high-risk patterns for VA in this population before they occur. Purpose The aim of the study was to describe mitral valve (MV) geometry and quantify traction forces (TF) using TTE in patients with benign MVP and AMVP, and to compare these parameters between these two populations. Methods This retrospective observational study included 22 patients, 18 with benign MVP and 8 with AMVP. MV geometry and TF were measured using TTE. MVP was defined as the displacement of one or both leaflets ≥ 2 mm above the mitral annulus (MA) plane in parasternal long-axis view, and AMVP as MVP combined with frequent or complex VA. Patients with significant mitral regurgitation were excluded to eliminate its potential modifying effect on TF. Clinical variables were obtained from electronic medical records. LV parameters and MV geometry were measured by TTE, and TF were quantified as the variation in distance between the PM and MA from proto to mesosystole in apical 3 chamber view. Results Clinical characteristics and echocardiographic measurements are presented in the Table. The groups were comparable in terms of age, gender, LV dimension, function, and Global Longitudinal Strain (GLS). As expected, the AMVP group exhibited more symptoms, pathological ECG findings, and abnormal Holter results. In terms of MV geometry, the AMVP group had larger prolapsing area and height, with predominantly bileaflet involvement. Mitral annular disjunction (MAD) was also significantly more frequent in this group. Regarding TF quantification, the AMVP group showed greater PM-MA distance in protosystole and a higher variation in this distance between proto- and mesosystole compared to the benign MVP group. Conclusion These results support the hypothesis that AMVP patients exhibit significantly higher TF during systole. While larger clinical trials are needed to reach firm conclusions, this parameter could constitute a new measurable characteristic of this population, contributing to phenotypic characterization and early identification of AMVP, potentially before the occurrence of a fatal event.

Nanoscale Cellular Traction Force Quantification: CRISPR-Cas12a Supercharged DNA Tension Sensors in Nanoclustered Ligand Patterns.

High-throughput measurement of cellular traction forces at the nanoscale remains a significant challenge in mechanobiology, limiting our understanding of how cells interact with their microenvironment. Here, we present a novel technique for fabricating protein nanopatterns in standard multiwell microplate formats (96/384-wells), enabling the high-throughput quantification of cellular forces using DNA tension gauge tethers (TGTs) amplified by CRISPR-Cas12a. Our method employs sparse colloidal lithography to create nanopatterned surfaces with feature sizes ranging from sub 100 to 800 nm on transparent, planar, and fully PEGylated substrates. These surfaces allow for the orthogonal immobilization of two different proteins or biomolecules using click-chemistry, providing precise spatial control over cellular signaling cues. We demonstrate the robustness and versatility of this platform through imaging techniques, including total internal reflection fluorescence microscopy, confocal laser scanning microscopy, and high-throughput imaging. Applying this technology, we measured the early stage mechanical forces exerted by 3T3 fibroblasts across different nanoscale features, detecting forces ranging from 12 to 56 pN. By integrating the Mechano-Cas12a Assisted Tension Sensor (MCATS) system, we achieved rapid and high-throughput quantification of cellular traction forces, analyzing over 2 million cells within minutes. Our findings reveal that nanoscale clustering of integrin ligands significantly influences the mechanical responses of cells. This platform offers a powerful tool for mechanobiology research, facilitating the study of cellular forces and mechanotransduction pathways in a high-throughput manner compatible with standard cell culture systems.

Structural model of a bacterial focal adhesion complex

Cell movement on surfaces relies on focal adhesion complexes (FAs), which connect cytoskeletal motors to the extracellular matrix to produce traction forces. The soil bacterium Myxococcus xanthus uses a bacterial FA (bFA), for surface movement and predation. The bFA system, known as Agl-Glt, is a complex network of at least 17 proteins spanning the cell envelope. Despite understanding the system dynamics, its molecular structure and protein interactions remain unclear. In this study, we utilize AlphaFold to generate models based on the known interactions and dynamics of gliding motility proteins. This approach provides us with a comprehensive view of the interactions across the entire complex. Our structural insights show the connection of essential functional modules throughout the cell envelope and offer an inspiring view of the force transduction mechanism from the inner molecular motor to the exterior of the cell.

A multifunctional sensor for cell traction force, matrix remodeling and biomechanical assays in self-assembled 3D tissues in vitro.

Cell-matrix interactions, mediated by cellular force and matrix remodeling, result in dynamic reciprocity that drives numerous biological processes and disease progression. Currently, there is no available method for directly quantifying cell traction force and matrix remodeling in three-dimensional matrices as a function of time. To address this long-standing need, we developed a high-resolution microfabricated device that enables longitudinal measurement of cell force, matrix stiffness and the application of mechanical stimulation (tension or compression) to cells. Here a specimen comprising of cells and matrix self-assembles and self-integrates with the sensor. With primary fibroblasts, cancer cells and neurons we have demonstrated the feasibility of the sensor by measuring single or multiple cell force with a resolution of 1 nN and changes in tissue stiffness due to matrix remodeling by the cells. The sensor can also potentially be translated into a high-throughput system for clinical assays such as patient-specific drug and phenotypic screening. We present the detailed protocol for manufacturing the sensors, preparing experimental setup, developing assays with different tissues and for imaging and analyzing the data. Apart from microfabrication of the molds in a cleanroom (one time operation), this protocol does not require any specialized skillset and can be completed within 4-5 h.

Developing an Algorithm Limiting the Longitudinal Acceleration of an Electric Vehicle

The electric traction drive is increasingly being applied as a device providing traction force on driving wheels. This is due to its reliable torque transmission to the driving wheels, step-less regulation of the traction force on the driving wheels depending on the driving conditions, and increased design capabilities. In terms of power, the electric traction drive has maximum torque at low speeds, which internal combustion engines lack. This property of the electric drive is not applied in urban vehicles, as not all passengers are comfortable with intensive acceleration. In modern vehicles with an electric traction drive, the maximum acceleration can be limited by software, which is the focus of this study. This paper aims to develop an algorithm capable of recognizing when the permissible longitudinal acceleration exceeds the limit and generating an action to maintain the acceptable acceleration level. The electric traction drive of a large-class electric bus was used as a control object. An algorithm and a control law are hereby developed, which reduce longitudinal acceleration using PI control. Both simulation modeling and full-scale tests on the electric bus were carried out to evaluate the performance and efficiency of the algorithm. In this paper, the authors also introduce the cumulative velocity concept and prove the operability and efficiency of the developed method.

Traction force microscopy of cardiomyocytes.

Traction force microscopy of cardiomyocytes.

Reconstruction of anterior talofibular ligament and posterior tibiotalar ligament enhance ankle stability after total talus replacement by finite element analysis

Total talus replacement has been demonstrated to increase ankle instability. However, no studies have explored how to enhance postoperative stability. This study aims to explore the effect of collateral ligament reconstruction on ankle stability by finite element analysis. The results identify that the reconstruction of the posterior talofibular ligament or anterior tibiotalar ligament has little effect on ankle stability. Besides, the reconstruction of the posterior tibiotalar ligament can significantly enhance the eversion stability. Additionally, the traction force of the fibula on the total talar prosthesis after reconstruction of the anterior talofibular ligament can significantly enhance ankle inversion and anterior stability.

Development of intelligent traction machine for tensioning and paying off construction of transmission lines

Monitoring the traction force and speed of the traction machine is crucial for timely discovering construction problems and avoiding accidents during the construction process of tension wire laying. The existing monitoring methods have low accuracy, are susceptible to environmental interference, and cannot achieve real-time monitoring. Therefore, this article has developed an intelligent traction machine suitable for tension line construction.The design scheme includes three modules: data acquisition and processing, data transmission, and software design. The data acquisition and processing module is responsible for real-time monitoring of traction force and traction speed, and converting the monitored data into digital signals through pressure sensors and speed sensors, and then processing them through a microcontroller. The data transmission module transmits monitoring data to the construction site terminal equipment and remote command center through LoRa wireless transmission technology, displays monitoring data on the terminal equipment, and realizes warning and control functions. At present, the intelligent traction machine has been applied in the tension wire laying construction of a 750 kV transmission line project in Guangdong, China and has achieved good results. Through continuous optimization and improvement, intelligent traction machines have practical conditions and broad application prospects.

Adsorption Force of Fibronectin Regulates Protein Reorganization, Desorption, and Endocytosis.

Protein adsorption on biomaterials occurs before cell adhesion. To adapt the properties of biomaterials, adhered cells may utilize and modify adsorbed proteins for survival and function. In this process, the protein-material interfacial force (Fad) is supposed to play vital roles, which, however, has received little attention. Here, we found that rat mesenchymal stem cells (rMSCs) can utilize the adsorbed fibronectin (FN) via reorganization, desorption, or endocytosis, and these utilization processes are regulated by Fad through regulating cell adhesion and force balance between the cell traction force and Fad. Furthermore, protein utilization has an Fad-dependent temporal sequence. On low Fad surface, FN endocytosis might happen prior to FN desorption and aggregation. This work confirms the importance of Fad in protein utilization and provides new insight into the mechanism by which cells process their surrounding ECM proteins, which may help to guide the design of better biomaterials.

Effects of forearm rotation on wrist flexor and extensor muscle activities

The forearm muscles coordinately control wrist motion, and their activity is affected by forearm rotation. Although forearm rotation has been implicated in the development of lateral and medial epicondylitis, its biomechanical background remains unknown. Therefore, the present study investigated the activity of wrist muscles in various forearm positions. Surface electromyography of the extensor carpi radialis brevis, extensor carpi ulnaris, flexor carpi radialis, and flexor carpi ulnaris was performed on 40 healthy upper limbs. We initially measured muscle strength and electromyographic activity (integrated electromyographic value per second) at maximum voluntary output towards wrist extension and flexion in a neutral position. We then assessed electromyographic activity under constant wrist torque (75% of maximum strength in the neutral position) in pronation, the neutral position, and supination. The percentage of maximum electromyographic activity was evaluated for each position. In wrist extension, the extensor carpi radialis brevis was activated during forearm pronation, while extensor carpi ulnaris activity did not change in any forearm position. In wrist flexion, the flexor carpi radialis was activated during forearm supination, while flexor carpi ulnaris activity was significantly lower with forearm pronation than in the neutral position. Since muscle activation increases traction force at the tendon origin, forearm positions that increase muscle activity may be a biomechanical risk factor for the development of tendinopathy. The present results are consistent with epidemiological and pathological findings on lateral and medial epicondylitis. These results provide insights into wrist biomechanics and the pathophysiology of lateral and medial epicondylitis.

The optimal control law of the power supplied to the wheeled vehicle in case of curvilinear movement

INTRODUCTION: Highly mobile wheeled vehicles are designed to move on roads and terrain in various road and soil conditions, which is accompanied by frequent and significant changes in traction forces and rolling resistance forces. In this regard, in order to maintain vehicle mobility and ensure low energy costs when performing transport tasks, it is necessary to continuously change the operating mode during movement from completely locked to differential in the case of a mechanical transmission. At the same time, the transmission operating mode selected by the driver is not always rational. Thus, the development of a law for controlling the power supplied to the propulsion system, ensuring minimal energy losses while maintaining vehicle mobility in widely varying road conditions, is an urgent task. PURPOSE OF THE STUDY: Increasing the energy efficiency of highly mobile wheeled vehicles by applying a control law for the power supplied to the propulsion system, adaptive to driving conditions. METHODOLOGY AND METHODS: Increasing the energy efficiency of movement can be achieved by reducing losses due to wheel slipping by controlling the power supplied to the propulsion unit. It is advisable to obtain the control law as a result of solving an optimization problem, where the loss power is chosen as the objective function, and the traction forces developed on each of the wheels are chosen as the varied values. At the same time, in order to maintain the possibility of vehicle movement, it is necessary to take into account that the total traction force on all wheels must be determined by external conditions and provided by the power plant. To solve the optimization problem, the Lagrange multiplier method was used. RESULTS AND SCIENTIFIC NOVELTY: The studies carried out made it possible to obtain in analytical form a unified law of adaptive control of the power supplied to the propulsors, applicable in a wide range of road conditions in both straight and curved motion, providing a close to optimal distribution of moments across the driving wheels of the machine, obtained as a result of numerical optimization. PRACTICAL SIGNIFICANCE: The application of the developed law for controlling the power supplied to the propulsors, based on the use in the process of movement of information only about the longitudinal and vertical forces, rotational speeds and angles of rotation of the wheels (trajectory radius), will improve the efficiency of performing transport tasks when moving a vehicle in continuously changing road conditions due to reducing the load on the driver in terms of controlling differential locks in comparison with a manual transmission both in straight and curved motion.

Biomechanical Outcomes of Glenoid Bone Graft Fixation Techniques: A Systematic Review.

The Latarjet and other bony augmentation procedures are commonly used to treat anterior shoulder instability in the setting of significant glenoid bone loss. Although several fixation strategies have been reported, the biomechanical strength of these techniques remains poorly understood. To perform a systematic review of the biomechanical strength of glenoid bony augmentation procedures for anterior shoulder instability. Systematic review; Level of evidence, 4. A systematic search of the Medline, Embase, Web of Science, and Cochrane Library databases was performed to identify biomechanical studies evaluating various fixation strategies for coracoid and other bone transfer procedures for anterior shoulder instability. Biomechanical results included load to failure with both compression and traction forces, stiffness, and cyclic displacement. The quality of included articles was assessed based on the Quality Appraisal for Cadaveric Studies (QUACS) scale. A total of 21 biomechanical studies comprising 486 specimens were included. The number of screws used and the addition of washers were found to significantly increase rigidity and load to failure. The comparison of fixation techniques demonstrated mixed results in load to failure between screw and alternative constructs including suture buttons and suture anchors. However, studies that tested graft displacement consistently found more graft displacement in buttons compared with screws. The median and mean of the QUACS scale were both 12, with a range of 10-13. Biomechanical studies consistently demonstrated that when glenoid bone grafts were fixed with screws, the number of screws and use of washers significantly increased construct rigidity and load to failure. Different metal screw materials and sizes did not consistently demonstrate a significant difference in biomechanical strength. There are mixed results when comparing suture buttons to screw fixation. The evaluated studies revealed that all double metal screw constructs and the majority of suture button and anchor constructs were able to withstand the glenohumeral load reflective of activities of daily living using a 150-N threshold.

Endothelial tip-cell position, filopodia formation and biomechanics require BMPR2 expression and signaling

Blood vessel formation relies on biochemical and mechanical signals, particularly during sprouting angiogenesis when endothelial tip cells (TCs) guide sprouting through filopodia formation. The contribution of BMP receptors in defining tip-cell characteristics is poorly understood. Our study combines genetic, biochemical, and molecular methods together with 3D traction force microscopy, which reveals an essential role of BMPR2 for actin-driven filopodia formation and mechanical properties of endothelial cells (ECs). Targeting of Bmpr2 reduced sprouting angiogenesis in zebrafish and BMPR2-deficient human ECs formed fewer filopodia, affecting cell migration and actomyosin localization. Spheroid assays revealed a reduced sprouting of BMPR2-deficient ECs in fibrin gels. Even more strikingly, in mosaic spheroids, BMPR2-deficient ECs failed to acquire tip-cell positions. Yet, 3D traction force microscopy revealed that these distinct cell behaviors of BMPR2-deficient tip cells cannot be explained by differences in force-induced matrix deformations, even though these cells adopted distinct cone-shaped morphologies. Notably, BMPR2 positively regulates local CDC42 activity at the plasma membrane to promote filopodia formation. Our findings reveal that BMPR2 functions as a nexus integrating biochemical and biomechanical processes crucial for TCs during angiogenesis.

Coordination of Focal Adhesion Nanoarchitecture and Dynamics in Mechanosensing for Cardiomyoblast Differentiation.

Focal adhesions (FAs) are force-bearing multiprotein complexes, whose nanoscale organization and signaling are essential for cell growth and differentiation. However, the specific organization of FA components to exert spatiotemporal activation of FA proteins for force sensing and transduction remains unclear. In this study, we unveil the intricacies of FA protein nanoarchitecture and that its dynamics are coordinated by a molecular scaffold protein, BNIP-2, to initiate downstream signal transduction for cardiomyoblast differentiation. Within the FAs, BNIP-2 regulates the nano-organization of focal adhesion kinase (FAK), and the dynamics of FAK, paxillin, and vinculin. Depletion of BNIP-2 resulted in altered focal adhesion numbers and sizes per cell, reduced traction force, and decreased FA sensitivity for mechanosensing. At the molecular level, the loss of BNIP-2 disrupted the FAK-paxillin signaling axis, where FAK inhibition reproduces the effects of BNIP-2 loss by impairing the phosphorylation of both FAK and paxillin. Mechanistically, BNIP-2 preferentially binds to constitutively active FAK and acts as a molecular scaffold to mediate interactions between FAK and paxillin and between paxillin and vinculin. We have validated BNIP-2's role in the FAK-paxillin signaling axis in human embryonic stem cells (hESC). Furthermore, we showed that depletion of BNIP-2 resulted in changes in signature gene targets at the cardiac progenitor stage of differentiation. In summary, we showed that the intricate interplay of FA nanoarchitecture and dynamics, governed by BNIP-2, is crucial for force transduction and biochemical signaling in driving cardiomyoblast differentiation.

Enhancing Rotator Cuff Repair in Rabbit Osteoporosis With Chitosan Quaternary Ammonium Salt-Coated Nickel-Titanium Memory Alloy Anchors.

For patients with osteoporosis and rotator cuff tears, there is still no consensus on current treatment methods. The material, structure, and number of anchors have important effects on the repair outcome. To investigate the use of chitosan quaternary ammonium salt-coated nickel-titanium memory alloy (NTMA) anchors to treat rotator cuff injury in shoulders with osteoporosis in a rabbit osteoporosis model. Controlled laboratory study. A novel winged NTMA anchor was designed to test in normal and osteoporotic bone models in vitro. These models were assessed for maximum failure load and bone damage in various traction directions. A chitosan-sodium alginate composite was coated onto NTMA anchor surfaces using glutaraldehyde cross-linking and electrostatic layering techniques. An osteoporotic rabbit model was created using ovariectomy combined with glucocorticoid treatment. A rabbit model with acute injury to the supraspinatus muscle was established and repaired using titanium alloy anchors, NTMA anchors, and coated NTMA (CNTMA) anchors. To evaluate the efficacy of the anchors, biomechanical testing and staining with hematoxylin and eosin were performed 6 and 12 weeks after surgery. A micro-computed tomography scan was performed 12 weeks after surgery. In the osteoporotic bone model, NTMA anchors exhibited greater failure loads than titanium anchors under 45° and 90° traction forces (P < .05). The surface-modified material showed a lower contact angle compared with unmodified material. Cell Counting Kit-8 (CCK-8) assays showed that the composite coating promoted osteoblast proliferation. The CNTMA anchor group exhibited the greatest maximum failure load at each time point. Hematoxylin and eosin staining revealed greater trabecular thickness in the CNTMA anchor group than in the other groups at 6 and 12 weeks after surgery. At 12 weeks after surgery, micro-computed tomography revealed an increased number and thickness of bone trabeculae in the NTMA anchor group, along with a widened trabecular gap (P < .05). After the NTMA anchor biplane unfolded, the gap between the biplane and anchor showed bone tissue growth. Chitosan quaternary ammonium salt-coated NTMA anchors enhanced fixation strength and promoted local osteogenesis during osteoporotic rotator cuff repair, suggesting that the use of these anchors facilitates the repair of osteoporotic rotator cuff injuries in osteoporotic bones. Innovations in anchor nailing may be effective in reducing rates of repair failure for rotator cuff tears combined with osteoporosis.