Traction Force Research Articles

Changes in Acromiohumeral Distance With Clinician-Applied and Self-Applied Inferior Glenohumeral Joint Mobilizations Measured Using Ultrasound Imaging

OBJECTIVE: To measure the change in acromiohumeral distance during clinician-applied and self-applied manual shoulder joint mobilization. We hypothesized that the acromiohumeral distance would be significantly greater with clinician-applied manual joint mobilizations (MJM) than with self-applied joint mobilization. DESIGN: Within-subject, repeated measures design METHODS: Nineteen healthy adults (mean age: 22.9 ± 1.2 years) participated. A traction force of 15% body weight was applied during MJM and self-applied joint mobilization (SJM). Acromiohumeral distance was measured via ultrasound imaging at rest (baseline) and during the two test conditions (2 trials each) to quantify inferior accessory motion. The transducer was placed at the anterolateral border of the acromion and the subacromial space was clearly visualized for acromiohumeral distance measurements. RESULTS: The ICC for acromiohumeral distance measurements ranged from 0.876 to 0.963. Changes in acromiohumeral distance during MJM (3.90 ± 0.51mm) were significantly greater than SJM (1.68 ± 0.49mm, p<0.001). AHD changes between sexes: MJM (female: 3.16 ± 0.58mm, male: 5.15 ± 0.90mm, p=0.060); SJM (female: 0.88 ± 0.51 mm, male 3.05 ± 0.90mm, p=0.029). CONCLUSIONS: Our acromiohumeral distance measurement methodology had excellent test-retest reliability. There was significantly more inferior humeral accessory motion with MJM than SJM. The acromiohumeral distance was 132% greater during MJM and was unchanged or less than resting baseline measurements in almost a third of participants during SJM.

Analysis of the traction forces of two adjacent linear induction motors

Linear induction motors (LIMs) are positioned head-to-tail in medium and low-speed maglev (MLSM) trains, and the interaction due to small spacing between two LIMs is not yet clear. In this work, based on the 2D electromagnetic field theory, the vector magnetic potential (VMP) of each region was solved, and the traction forces of two adjacent LIMs were derived. Subsequently, the correctness of the theoretical model was verified by simulation. Finally, the effects of the spacing, wiring type, pole pitch, speed, etc., on the traction forces of two adjacent LIMs were analyzed. The results show that the traction force of LIM1 (arranged in front) is almost unaffected by LIM2 (arranged behind LIM1), while that of LIM2 fluctuates periodically with the spacing, and the smaller the spacing, the greater the fluctuation amplitude. Meanwhile, the larger the pole pitch, the more the pole number, the greater the slip frequency, and the lower the speed, the smaller the effect of LIM1 on LIM2. When the spacing takes 1.1 to 1.6 times the pole pitch, the traction force of LIM2 is larger than that of LIM1. The achievements can provide technical support for enhancing the traction performance of the LIMs in the MLSM trains.

Modified tractive force approach for sediment transport under bank seepage

ABSTRACT The current research focuses on integrating the impact of seepage into the tractive force method for sediment particles situated on porous riverbanks. A formula is developed using the tractive force approach to calculate the critical shear stress acting on sediment particles under steady seepage conditions. The study reveals that the hydraulic gradient influences the critical shear stress, which rises with higher hydraulic gradients. Additionally, application of the derived equation is demonstrated through a hypothetical channel design problem.

Suppression of non-muscle myosin II boosts T cell cytotoxicity against tumors.

Increasing evidence highlights the importance of immune mechanoregulation in establishing and sustaining tumor-specific cytotoxicity required for desirable immunotherapeutic outcomes. However, the molecular connections between mechanobiological inputs and outputs and the designated immune activities remain largely unclear. Here, we show that partial inhibition of non-muscle myosin II (NM II) augmented the traction force exerted by T cells and potentiated T cell cytotoxicity against tumors. By using T cells from mice and patients with cancer, we found that NM II is required for the activity of NKX3-2 in maintaining the expression of ADGRB3, which shapes the filamentous actin (F-actin) organization and ultimately attributes to the reduced traction force of T cells in the tumor microenvironment. In animal models, suppressing the NM II-NKX3-2-ADGRB3 pathway in T cells effectively suppressed tumor growth and improved the efficacy of the checkpoint-specific immunotherapy. Overall, this work provides insights into the biomechanical regulation of T cell cytotoxicity that can be exploited to optimize clinical immunotherapies.

MYH1 deficiency disrupts outer hair cell electromotility, resulting in hearing loss.

Myh1 is a mouse deafness gene with an unknown function in the auditory system. Hearing loss in Myh1-knockout mice is characterized by an elevated threshold for the auditory brainstem response and the absence of a threshold for distortion product otoacoustic emission. Here, we investigated the role of MYH1 in outer hair cells (OHCs), crucial structures in the organ of Corti responsible for regulating cochlear amplification. Direct whole-cell voltage-clamp recordings of OHCs revealed that prestin activity was lower in Myh1-knockout mice than in wild-type mice, indicating abnormal OHC electromotility. We analyzed whole-exome sequencing data from 437 patients with hearing loss of unknown genetic causes and identified biallelic missense variants of MYH1 in five unrelated families. Hearing loss in individuals harboring biallelic MYH1 variants was non-progressive, with an onset ranging from congenital to childhood. Three of five individuals with MYH1 variants displayed osteopenia. Structural prediction by AlphaFold2 followed by molecular dynamic simulations revealed that the identified variants presented structural abnormalities compared with wild-type MYH1. In a heterogeneous overexpression system, MYH1 variants, particularly those in the head domain, abolished MYH1 functions, such as by increasing prestin activity and modulating the membrane traction force. Overall, our findings suggest an essential function of MYH1 in OHCs, as observed in Myh1-deficient mice, and provide genetic evidence linking biallelic MYH1 variants to autosomal recessive hearing loss in humans.

3D Micropatterned Traction Force Microscopy: A Technique to Control 3D Cell Shape While Measuring Cell-Substrate Force Transmission.

Cell shape and function are intimately linked, in a way that is mediated by the forces exerted between cells and their environment. The relationship between cell shape and forces has been extensively studied for cells seeded on flat 2D substrates, but not for cells in more physiological 3D settings. Here, a technique called 3D micropatterned traction force microscopy (3D-µTFM) to confine cells in 3D wells of defined shape, while simultaneously measuring the forces transmitted between cells and their microenvironment is demonstrated. This technique is based on the 3D micropatterning of polyacrylamide wells and on the calculation of 3D traction force from their deformation. With 3D-µTFM, it is shown that MCF10A breast epithelial cells exert defined, reproducible patterns of forces on their microenvironment, which can be both contractile and extensile. Cells switch from a global contractile to extensile behavior as their volume is reduced are further shown. The technique enables the quantitative study of cell mechanobiology with full access to 3D cellular forces while having accurate control over cell morphology and the mechanical conditions of the microenvironment.

Single-Cell Hypertrophy Promotes Contractile Function of Cultured Human Airway Smooth Muscle Cells via Piezo1 and YAP Auto-Regulation.

Severe asthma is characterized by increased cell volume (hypertrophy) and enhanced contractile function (hyperresponsiveness) of the airway smooth muscle cells (ASMCs). The causative relationship and underlying regulatory mechanisms between them, however, have remained unclear. Here, we manipulated the single-cell volume of in vitro cultured human ASMCs to increase from 2.7 to 5.2 and 8.2 × 103 μm3 as a simulated ASMC hypertrophy by culturing the cells on micropatterned rectangular substrates with a width of 25 μm and length from 50 to 100 and 200 μm, respectively. We found that as the cell volume increased, ASMCs exhibited a pro-contractile function with increased mRNA expression of contractile proteins, increased cell stiffness and traction force, and enhanced response to contractile stimulation. We also uncovered a concomitant increase in membrane tension and Piezo1 mRNA expression with increasing cell volume. Perhaps more importantly, we found that the enhanced contractile function due to cell volume increase was largely attenuated when membrane tension and Piezo1 mRNA expression were downregulated, and an auto-regulatory loop between Piezo1 and YAP mRNA expression was also involved in perpetuating the contractile function. These findings, thus, provide convincing evidence of a direct link between hypertrophy and enhanced contractile function of ASMCs that was mediated via Piezo1 mRNA expression, which may be specifically targeted as a novel therapeutic strategy to treat pulmonary diseases associated with ASMC hypertrophy such as severe asthma.

Suitable Method for Improving Friction Performance of Magnetic Wheels with Metal Yokes

A magnetic-wheeled robot is a type of robot that inspects large steel structures instead of humans, and it can run on a three-dimensional path by using wheels with built-in permanent magnets. For the robots to work safely, their magnetic wheels require both magnetic attractive forces and friction forces. Planetary-geared magnetic wheels, which we have developed, make direct contact with their yokes on the running surface to ensure their magnetic attractive force. However, this design decreases their frictional performance more than common magnetic wheels covered with soft materials. Therefore, the yokes require methods that can improve their frictional performance without decreasing their attractive force. To consider the best method for the use of magnetic wheels, this study has run experiments with five types of yokes, which have different processing. As a result, the yokes with corroded surfaces could have maintained the attractive force more than 90% of the time and increased their traction forces by about 36% in static conditions and about 30% in dynamic conditions compared to yokes with no machining. The main reasons for these experimental results are that the rust layer has stable irregularities on the surface and includes ferromagnetic materials.

Substrate stiffness-dependent activation of Hippo pathway in cancer associated fibroblasts

The tumor microenvironment (TME) comprises a heterogenous cell population within a complex three-dimensional (3D) extracellular matrix (ECM). Stromal cells within this TME are altered by signaling cues from cancer cells to support uncontrolled tumor growth and invasion events. Moreover, the ECM also plays a fundamental role in tumor development through pathological remodeling, stiffening and interaction with TME cells. In healthy tissues, Hippo signaling pathway actively contributes to tissue growth, cell proliferation and apoptosis. However, in cancer, the Hippo signaling pathway is highly dysregulated, leading to nuclear translocation of the YAP/TAZ complex, which directly contributes to uncontrolled cell proliferation and tissue growth, and ECM remodeling and stiffening processes. Here, we compare the effect of increasing cell culture substrate stiffness, derived from tumor progression, upon the dysregulation of the Hippo signaling pathway in colorectal cancer-associated fibroblasts (CAFs) and normal colorectal fibroblasts (NFs). We correlate the dysregulation of Hippo pathway with the magnitude of the traction forces exerted by healthy and malignant stromal cells. We found that ECM stiffening is crucial in Hippo pathway dysregulation in CAFs, but not in normal fibroblasts.

Three-Dimensional Site Response Analysis of Clay Soil Considering the Effects of Soil Behavior and Type

To understand changes in bedrock motion at the ground surface, frequency effects, and spatial distribution within the soil, it is important to look at how a site responds to earthquakes. This is important for soil–structure interaction in structural and geotechnical earthquake engineering. This study deals with the effect of classifying clays according to shear wave velocity (stiff/medium/soft) and nonlinearity in behavior (linear/nonlinear) on the analysis of the site response. A 3D soil model with a combination of free fields and quiet boundaries and advanced constitutive models for soil to obtain accurate results was used to conduct this study. A strong TABAS earthquake was used to excite the compliant base of the model after converting the velocity record of TABAS to an equivalent surface traction force using a horizontal force–time history proportional to the velocity–time history. This study reveals that the site response analysis is affected by the type of clay soil and the soil material behavior, with soft clay soil causing higher PGV and PGV values in the linear case and lower values in the nonlinear case due to soil yielding, which causes soil response attenuation. This results in extremely conservative and expensive building designs when linear soil behavior is adopted. On the other hand, the applied earthquake exhibits greater attenuation at longer frequencies and greater amplification at mid and short frequencies. However, at frequencies near the applied earthquake frequency, neither attenuation nor amplification occurs. Furthermore, nonlinear soil behavior is crucial for soil evaluation and foundation design due to higher octahedral shear strain and settlement values, especially in softer soils, resulting from extensive plastic deformation.

Force-mediated recruitment and reprogramming of healthy endothelial cells drive vascular lesion growth

Force-driven cellular interactions are crucial for cancer cell invasion but remain underexplored in vascular abnormalities. Cerebral cavernous malformations (CCM), a vascular abnormality characterized by leaky vessels, involves CCM mutant cells recruiting wild-type endothelial cells to form and expand mosaic lesions. The mechanisms behind this recruitment remain poorly understood. Here, we use an in-vitro model of angiogenic invasion with traction force microscopy to reveal that hyper-angiogenic Ccm2-silenced endothelial cells enhance angiogenic invasion of neighboring wild-type cells through force and extracellular matrix-guided mechanisms. We demonstrate that mechanically hyperactive CCM2-silenced tips guide wild-type cells by transmitting pulling forces and by creating paths in the matrix, in a ROCKs-dependent manner. This is associated with reinforcement of β1 integrin and actin cytoskeleton in wild-type cells. Further, wild-type cells are reprogrammed into stalk cells and activate matrisome and DNA replication programs, thereby initiating proliferation. Our findings reveal how CCM2 mutants hijack wild-type cell functions to fuel lesion growth, providing insight into the etiology of vascular malformations. By integrating biophysical and molecular techniques, we offer tools for studying cell mechanics in tissue heterogeneity and disease progression.

Canine pillar bone bearing traction method of skull external fixator combined with nickel-titanium memory alloy spring for unilateral cleft lip and palate with severe facial skeletal hypoplasia

Background: For unilateral cleft lip and palate severe midfacial skeletal dysplasia, external skull fixator combined with nickel titanium memory alloy spring was used to treat canine pillar bone bearing traction. Methodology: Patients (n = 200) with unilateral cleft lip and palate and severe midfacial skeletal hypoplasia who were treated in our hospital within three years were divided into control group (treated with trans suture traction osteogenesis) while the observation group was treated with skull external fixator combined with nickel titanium memory alloy spring supporting force traction of canine bone. Results: After applying significantly different traction forces to the maxillary tissues on both sides of the patient, the patient was treated with appropriate traction correction, orthodontic treatment and moderate traction on the facial arch to effectively reduce the recurrence of the disease after surgery. Compared with the control group, the curative effect in all aspects was better and the asymmetry rate was lower. Conclusion: Canine strut bone traction method of external skull fixation combined with nickel-titanium memory alloy spring was applied for severe facial skeletal dysplasia caused by unilateral cleft lip and palate. For this purpose, reasonable and scientific treatment methods were provided for early correction and treatment of the disease. Keywords: External fixator of skull; nickel titanium memory alloy spring; bone bearing traction of canine pillar; unilateral cleft lip and palate; severe midfacial skeletal dysplasia; clinical research.

Current Treatment Approaches for Full-Thickness and Non-Thickness Macula Hole in Pathological Myopia

Full-thickness and non-full-thickness macular holes seen in pathological myopia constitute a special subgroup in terms of vitretoretinal surgery with their formation mechanisms, progression and response to treatment. Compared to idiopathic macular holes, it has different features in that more complex tractional components are involved in its pathogenesis and tissue degeneration and atrophy play a role in pathological myopia. The determination of surgical indications, timing, and the choice of treatment for these cases should be tailored based on the pathology’s characteristics and the potential benefits of the surgery. The aim of surgical treatment is to eliminate tractional forces and restore the anatomical structure. This article aims to evaluate the treatment approaches for full-thickness and non full-thickness macular holes in pathological myopia by reviewing the current literature, thereby contributing to clinical practices in this field.

Traction on Rods within Cylinders Containing Grains: An Analogy with the Upward Movement of Trees in Tornadoes

In this work, the frictional traction forces developing in the annular space between two concentric vertical cylinders consisting of the outer surface of a cylindrical rod and the inner sidewall of a wider circular cylinder will be analyzed. The experiments carried out for this study allowed us to measure the traction on the rod for several filling heights, H. For the rod, it is possible to find a linear relation between the theoretically computed traction Trod and the traction measured experimentally, TrodM. Based on these results, it is possible to understand the fascinating phenomenon of the lifting, by the rod, of the weights of the mass of grains and of the outer cylinder. Finally, a physical analogy between this problem and the upward movement of trees in tornadoes can be identified.

Investigation of Cell Mechanics and Migration on DDR2-Expressing Neuroblastoma Cell Line.

Neuroblastoma is a devastating disease accounting for ~15% of all childhood cancer deaths. Collagen content and fiber association within the tumor stroma influence tumor progression and metastasis. High expression levels of collagen receptor kinase, Discoidin domain receptor II (DDR2), are associated with the poor survival of neuroblastoma patients. Additionally, cancer cells generate and sustain mechanical forces within their environment as a part of their normal physiology. Despite this, evidence regarding whether collagen-activated DDR2 signaling dysregulates these migration forces is still elusive. To address these questions, a novel shRNA DDR2 knockdown neuroblastoma cell line (SH-SY5Y) was engineered to evaluate the consequence of DDR2 on cellular mechanics. Atomic force microscopy (AFM) and traction force microscopy (TFM) were utilized to unveil the biophysical altercations. DDR2 downregulation was found to significantly reduce proliferation, cell stiffness, and cellular elongation. Additionally, DDR2-downregulated cells had decreased traction forces when plated on collagen-coated elastic substrates. Together, these results highlight the important role that DDR2 has in reducing migration mechanics in neuroblastoma and suggest DDR2 may be a promising novel target for future therapies.

Photo-tunable hydrogels reveal cellular sensing of rapid rigidity changes through the accumulation of mechanical signaling molecules.

Cells use traction forces to sense mechanical cues in their environment. While the molecular clutch model effectively explains how cells exert more forces on stiffer substrates, it falls short in addressing their adaptation to dynamic mechanical fluctuations prevalent in tissues and organs. Here, using hydrogel with photo-responsive rigidity, we show that cells' response to rigidity changes is frequency dependent. Strikingly, at certain frequencies, cellular traction forces exceed those on static substrates 4-fold stiffer, challenging the established molecular clutch model. We discover that the discrepancy between the rapid adaptation of traction forces and the slower deactivation of mechanotransduction signaling proteins results in their accumulation, thereby enhancing long-term cellular traction in dynamic settings. Consequently, we propose a new model that melds immediate mechanosensing with extended mechanical signaling. Our study underscores the significance of dynamic rigidity in the development of synthetic biomaterials, emphasizing the importance of considering both immediate and prolonged cellular responses.

Neutrophils exhibit flexible migration strategies and trail formation mechanisms on varying adhesive substrates

Substrate anchorage is essential for cell migration and actin polymerization at cell front and myosin contractility at cell rear are known to govern cell forward movement. Yet their differential driving strategies for neutrophil migration on distinct adhesiveness substrates and their contributions to the migration-induced trail formation remain unclear. Here we explore the morphological changes, migration dynamics, and trail formation of neutrophils on ICAM-1 and PLL substrates, with a focus on the relationships among adhesive forces, traction forces, and out-of-plane forces. Results indicate that, on ICAM-1, neutrophil migration and trail formation rely on the coordinated interactions of Arp2/3 and myosin, along with biochemical regulation (via Syk and calpain) of adhesion and de-adhesion. This pattern leads to traction forces being concentrated at relatively fewer adhesive sites, facilitating cell forward migration. On PLL, however, neutrophils primarily depend on Arp2/3-mediated actin polymerization, resulting in a broader distribution of traction forces and weaker adhesions, which allows for higher leading-edge migrating velocities. Elevated membrane tension and out-of-plane forces generated by bleb protrusions on PLL reduce the reliance on myosin-driven contraction at the trailing edge, enabling easier tail detachment through elastic recoil. This work highlights the differential impact of substrate adhesiveness on neutrophil migration and trail formation and dynamics, providing new insights into cell migration mechanisms and potential therapeutic targets for inflammatory and immune-related disorders.

Influences of mechanical decompression using different forces on knee joint space, range of motion, and hamstring flexibility in asymptomatic subjects

INTRODUCTION: Knee joint decompression is one of the promising methods for the treatment of osteoarthritis. Yet, the most appropriate decompression force is not conclusive. OBJECTIVES: To compare the effect of different distraction force magnitudes on knee joint space, active range of motion (ROM), hamstring flexibility, and self-reported discomfort in asymptomatic subjects. METHODS AND MATERIALS: Twenty-five asymptomatic participants were recruited in this study. The dominant knee was distracted for 30 minutes in a 30° flexion position using three force magnitudes (10%, 20%, and 30% body weight (BW)). The traction forces were randomized with one week in between knee distractions. Joint space, range of motion (ROM), and hamstring flexibility were assessed before, immediately after, and 30 minutes after the distraction. The self-reported discomfort was assessed immediately after the distraction only. RESULTS: Medial joint space, ROM, and discomfort showed a significant difference between different force magnitudes post-distraction. The 20% and 30% BW force magnitudes significantly, but equally, increased joint space and ROM post distraction. The discomfort level was directly related to distraction force magnitude and the least comforting was the 30% BW force. Follow-up data was not significantly different than that for post-distraction. Hamstring muscle flexibility showed a significant. Yet, small increase after the 30% BW distraction force. CONCLUSION: Continued mechanical distraction of the knee joint using force magnitudes of 20% and 30% of body weight was effective in increasing medial joint space, active knee ROM, and hamstring flexibility in asymptomatic individuals. 20% force magnitude was more comfortable than the 30% percent.

CHARACTERIZATION OF ALUMINIUM METAL MATRIX COMPOSITES REINFORCED WITH SILICON CARBIDE AND NICKEL PARTICULATES

This research article presents the procedure for the fabrication of Aluminium alloy (LM25) based metal matrix composites containing particulates of silicon carbide (10 wt. %) and nickel (0, 5 and 10 wt. %). Using the vortex casting technique, three composites were formulated and characterized as per ASTM standards. Microstructure analysis using "scanning electron microscopy" reveals the uniform distribution of reinforcing particulates within the base matrix without clustering. "Energy dispersive spectroscopy" illustrates the presence of ingredients within the composites. "X-ray diffraction" patterns indicate the formation of mesoporous NiSiAl compound within the composite resulting from internal reactions. The "optical microscopy" reveals the refinement of grain structure with the inclusion of nickel particulates within the composites. The influence of the composition of reinforcing particulates that is, silicon carbide and nickel on the properties of the base matrix was explored. An enhancement in the microhardness, tensile strength, wear resistance and traction force and a reduction in friction coefficient was observed together with a marginal reduction in elongation and the porosity level is also under the controlled limits (<5%).

MIXED PATHOPHYSIOLOGIES OF LAMELLAR MACULAR HOLES AND RELATED DISEASES: A Multimodal Optical Coherence Tomography-Based Study.

To investigate the characteristics of mixed pathophysiologies in lamellar macular holes (LMHs) and related diseases using multimodal optical coherence tomography. Overall, 126 eyes diagnosed with LMH, epiretinal membrane foveoschisis, or macular pseudohole using the horizontal B-scan image according to the definition proposed by Hubschman et al in 2020 were analyzed using multimodal optical coherence tomography imaging including horizontal and vertical 5-line B-scan, radial scan, and macular three-dimensional volume scan images. If at least two diagnostic criteria for LMH, epiretinal membrane foveoschisis, or macular pseudohole were satisfied in these scans, the patient was diagnosed as having a "mixed type." Retinal traction force was quantitatively evaluated by measuring the maximum depth of the retinal folds using en-face images. Mixed types constituted 34.1% of the cases. The LMH-related mixed group demonstrated intermediate characteristics between the epiretinal membrane foveoschisis/macular pseudohole and true LMH groups in terms of retinal traction and LMH-specific features and had a significant positive correlation between the maximum depth of the retinal folds and mean M-CHARTS scores (P = 0.034). A thorough optical coherence tomography analysis is necessary to accurately diagnose LMH and related diseases. A significant positive correlation was observed between the maximum depth of the retinal folds and the degree of metamorphopsia in the LMH-related mixed group.