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The shield building of the AP1000 nuclear power plant serves as a crucial protective barrier against radioactive substances. However, past research indicates that structures are susceptible to experiencing aftershocks, which may lead to unforeseeable damage and potential radioactive material leakage. To address this issue, a finite element model of the shield building was established with the damage indexes of the tensile and compressive damage selected for further model analysis. According to the fundamental theory of reliability, the traditional incremental dynamic analysis method was used to analyze the seismic fragility of the shield building by inputting mainshock and aftershock sequences with three strength ratios. The results indicate that the seismic fragility of shield building may be underestimated without considering the influence of aftershocks and the damage state presents an upward tendency as the strength ratio increases. However, the cumulative damage caused by aftershocks is unlikely to exceed the initial damage induced by the corresponding mainshock. Overall, the aggravation of the compressive damage is less pronounced than the increase of the tensile damage as the strength ratio increases.

Background: Prevention of adhesion formation following flexor tendon repair is essential for restoration of normal finger function. Although many medications have been studied in the experimental setting to prevent adhesions, clinical application is limited due to the complexity of application and delivery in clinical translation. Methods: In this study, optimal dosages of gelatin and pentamidine were validated by gelatin concentration test. Following cell viability, cell migration, live and dead cell, and cell adhesion assay of the Turkey tenocytes, a model of Turkey tendon repair was established to evaluate the effectiveness of the Pentamidine-Gelatin sheet. Results: Pentamidine carried with gelatin, a Food and drug administration (FDA) approved material for drug delivery, showed good dynamic release, biocompatibility, and degradation. The optimal dose of pentamidine (25ug) was determined in the in vivo study using tenocyte viability, migration, and cell adhesion assays. Further biochemical analyses demonstrated that this positive effect may be due to pentamidine downregulating the Wnt signaling pathway without affecting collagen expression. Conclusions: We tested a FDA-approved antibiotic, pentamidine, for reducing adhesion formation after flexor tendon repair in both in vitro and in vivo using a novel turkey animal model. Compared with the non-pentamidine treatment group, pentamidine treated turkeys had significantly reduced adhesions and improved digit function after six weeks of tendon healing. The translational potential of this article: This study for the first time showed that a common clinical drug, pentamidine, has a potential for clinical application to reduce tendon adhesions and improve tendon gliding function without interfering with tendon healing.

Rayleigh waves are vertically elliptical surface waves traveling along the ground surface, which have been demonstrated to pose potential damage to buildings. However, traditional seismic barriers have limitations of high-frequency narrow bandgap or larger volume, which have constraints on the application in practical infrastructures. Thus, a new type seismic metamaterial needs to be further investigated to generate wide low-frequency bandgaps. Firstly, a resonator with a three-vibrator is proposed to effectively attenuate the Rayleigh waves. The attenuation characteristics of the resonator are investigated through theoretical and finite element methods, respectively. The theoretical formulas of the three-vibrator resonator are established based on the local resonance and mass-spring theories, which can generate wide low-frequency bandgaps. Subsequently, the frequency bandgaps of the resonator are calculated by the finite element software COMSOL5.6 based on the theoretical model and Floquet–Bloch theory with a wide ultra-low-frequency bandgap in 4.68–22.01 Hz. Finally, the transmission spectrum and time history analysis are used to analyze the influences of soil and material damping on the attenuation effect of resonators. The results indicate that the resonator can generate wide low-frequency bandgaps from 4.68 Hz to 22.01 Hz and the 10-cycle resonators could effectively attenuate Raleigh waves. Furthermore, the soil damping can effectively attenuate seismic waves in a band from 1.96 Hz to 20 Hz, whereas the material of the resonator has little effect on the propagation of the seismic waves. These results show that this resonator can be used to mitigate Rayleigh waves and provide a reference for the design of surface waves barrier structures.

Seismic surface waves carry significant energy that poses a major threat to structures and may trigger damage to buildings. To address this issue, the implementation of periodic barriers around structures has proven effective in attenuating seismic waves and minimizing structural dynamic response. This paper introduces a framework for seismic surface wave barriers designed to generate multiple ultra-low-frequency band gaps. The framework employs the finite-element method to compute the frequency band gap of the barrier, enabling a deeper understanding of the generation mechanism of the frequency band gap based on vibrational modes. Subsequently, the transmission rates of elastic waves through a ten-period barrier were evaluated through frequency–domain analysis. The attentional effects of the barriers were investigated by the time history analysis using site seismic waves. Moreover, the influence of the soil damping and material damping are separately discussed, further enhancing the assessment. The results demonstrate the present barrier can generate low-frequency band gaps and effectively attenuate seismic surface waves. These band gaps cover the primary frequencies of seismic surface waves, showing notable attenuation capabilities. In addition, the soil damping significantly contributes to the attenuation of seismic surface waves, resulting in an attenuation rate of 50%. There is promising potential for the application of this novel isolation technology in seismic engineering practice.

Purpose: To investigate the gliding resistance dynamics between the supraspinatus (SSP) tendon and the coracoacromial arch, both before and after subacromial decompression (anterolateral acromioplasty) and acromion resection (acromionectomy). Methods: Using 4 fresh-frozen cadaveric shoulders, acromion shapes were classified (2 type I and 2 type III according to Bigliani). Subacromial bursa and coracoacromial ligament maintenance replicated physiologic sliding conditions. Gliding resistance was measured during glenohumeral abduction (0° to 60°) in internal rotation (IR) and external rotation (ER). Peak gliding resistance between the SSP tendon and the coracoacromial arch was determined and compared between intact, anterolateral acromioplasty, and acromionectomy. Results: Peak SSP gliding resistance during abduction in an intact shoulder was significantly higher in IR than in ER (4.1 vs 2.1 N, P < .001). The mean peak SSP gliding resistance during 0° to 60° glenohumeral abduction in IR in the intact condition was significantly higher compared with the subacromial decompression condition (4.1 vs 2.8 N, P = .021) and with the acromionectomy condition (4.1 vs 0.9 N, P < .001). During 0° to 60° glenohumeral abduction in ER, mean peak SSP gliding resistance in the intact condition was not significantly different compared with the subacromial decompression condition (2.1 vs 2.0 N, P = .999). The 2 specimens with a hooked (i.e. type III) acromion showed significantly higher mean peak SSP gliding resistance during glenohumeral abduction in IR and ER when compared with the 2 specimens with a flat (i.e. type I) acromion (IR: 5.8 vs 3.0 N, P = .006; ER: 2.8 vs 1.4 N, P = .001). Conclusions: In this cadaveric study, peak gliding resistance between the SSP tendon and the coracoacromial arch during combined abduction and IR was significantly reduced after anterolateral acromioplasty and was significantly higher in specimens with a hooked acromion. Clinical Relevance: The clinical benefit of subacromial decompression remains unclear. This study suggests that anterolateral acromioplasty might reduce supraspinatus gliding resistance in those with a hooked acromion and in the typical “impingement” position.

Pile tip post-grouting technology has been widely adopted in pile foundations to improve its bearing characteristics. Grouting in the pile tip leads to the grouting cement spreading along the pile body to a certain extent. To better understand the grout diffusion mechanism along the pile body returned, a total of 45 groups of laboratory model tests were carried out on sand, with different grouting pressures, grout volumes, and soil stress histories taken into account. By comparing the characteristics of the grouted bulbs, the grout diffusion mechanism along the pile body returned was revealed. Combined with the test results, a simplified model to describe the grout diffusion pattern and the corresponding grouting mode of grouting cement along the pile body returned during the process of pile tip post-grouting was proposed. This model can comprehensively reflect the grout diffusion characteristics along the pile body, with different grouting conditions and soil stress histories taken into account.

Rotator cuff (RC) attaches to humerus across a triphasic yet continuous tissue zones (bone-fibrocartilage-tendon), termed “enthesis”. Regrettably, rapid and functional enthesis regeneration is challenging after RC tear. The existing grafts bioengineered for RC repair are insufficient, as they were engineered by a scaffold that did not mimic normal enthesis in morphology, composition, and tensile property, meanwhile cannot simultaneously stimulate the formation of bone-fibrocartilage-tendon tissues. Herein, an optimized decellularization approach based on a vacuum aspiration device (VAD) was developed to fabricate a book-shaped decellularized enthesis matrix (O-BDEM). Then, three recombinant growth factors (CBP-GFs) capable of binding collagen were synthesized by fusing a collagen-binding peptide (CBP) into the N-terminal of BMP-2, TGF-β3, or GDF-7, and zone-specifically tethered to the collagen of O-BDEM to fabricate a novel scaffold (CBP-GFs/O-BDEM) satisfying the above-mentioned requirements. After ensuring the low immunogenicity of CBP-GFs/O-BDEM by a novel single-cell mass cytometry in a mouse model, we interleaved urine-derived stem cell-sheets into this CBP-GFs/O-BDEM to bioengineer an enthesis-like graft. Its high-performance on regenerating enthesis was determined in a canine model. These findings indicate this CBP-GFs/O-BDEM may be an excellent scaffold for constructing enthesis-like graft to patch large/massive RC tears, and provide breakthroughs in fabricating graded interfacial tissue.

The construction process of a cast-in-situ bored pile is too complicated to be described by the cavity expansion theory with a single process. An exact unified semi-analytical solution for both cylindrical and spherical cavities reverse expansion after unloading in drained soil is developed. The non-associated Mohr-Coulomb model and definition of logarithmic strain are adopted in the reverse plastic zone. This model can be used to solve the stress and displacement fields of the soil around a bored pile along both the horizontal and depth directions. Parametric analysis shows that the effect of the unloading phase does not change the ultimate pressure of cavity reverse expansion compared with in situ expansion. The cavity cannot re-expand to its initial radius even though the cavity pressure reloads to the initial value. The increase of internal friction angle, cohesion, and Young's modulus has a positive effect on radius recovery, while the dilatancy angle has a negative effect. A simulation of the construction process of cast-in-situ bored piles is presented, where the role of boring, mud wall protection, and concrete placement is defined. An example that describes the stress and displacement fields around a pile shows that the total radial displacement of soil around the pile is dominated by contraction displacement. And it is closely related to depth and horizontal distance. The results of both parameter analysis and example analysis demonstrate that a low reverse cavity pressure corresponds to a stress-reduction area surrounding the cavity.

Chronic rotator cuff tears are debilitating diseases which significantly affect patients’ quality of life and pose substantial financial burden to the society. The intraoperative reparability of injured tendon and postoperative probability of tendon retear are highly associated with the quality of torn muscles, specifically, the severity of muscle atrophy and fatty infiltration. Animal models that reproduce the characteristic muscle pathology after rotator cuff injury have been developed and used to provide insight into the underlying biology and pathophysiology. In this review, we briefly summarize the current information obtained from preclinical animal studies regarding the degenerative change of cuff muscle subsequent to tendon release and/or suprascapular nerve denervation. Importantly, we focus on the potential translational therapeutic targets or agents for the prevention or reversal of muscle atrophy and fatty infiltration. While further studies are warranted to assess the safety and efficacy of novel therapies derived from these preclinical animal research, we believe that their clinical translation for the treatment of rotator cuff disorders is on the horizon. The Translational potential of this article: Novel therapeutic strategies described in this review from preclinical animal studies hold a great translational potential for preventing or reversing rotator cuff muscle pathology, while further assessments on their safety and efficacy are warranted.

The selection of grouting methods and parameters significantly affects the improvement in the pile-bearing capacity of cast-in-place bored piles. This study proposes a comprehensive set of test methods for constructing model piles, performing grouting at the pile tip and pile side. A series of single-pile grouting and static load tests were conducted using these test methods. The results reveal that pile-side grouting is more effective in controlling pile settlement compared to tip grouting. Furthermore, tip-side-combined grouting exhibits superior reinforcement effects compared to the other two grouting methods. After grouting, a grout bubble is formed at the outlet, consisting of a compact diffusion zone internally and a split diffusion zone externally. Additionally, a vertical diffusion of grout occurs along the pile body, establishing a lateral friction resistance enhancement region. Within this region, the lateral friction resistance of the pile shows a negative correlation with the distance from the grouting outlet. The test results emphasize the significance of grouting volume and its impact on the bearing capacity, settlement control, lateral friction resistance, and grout bubble size in grouted piles, while the influence of variation in grouting pressure in a small range on bearing characteristics is not significantly apparent.

Allogenic tendons grafts sourced from intrasynovial tendons are often used for tendon reconstruction. Processing is achieved through repetitive freeze–thaw cycles followed by lyophilization. Soaking the lyophilized tendon in saline (0.9%) for 24 h is the standard practice for rehydration. However, data supporting saline rehydration over the use of other hydrating solutions are scant. The purpose of the current study was to compare the effects of different rehydration solutions on biomechanical properties of lyophilized tendon allograft. A total of 36 canine flexor digitorum profundus tendons were collected, five freeze–thaw cycles followed by lyophilization were performed for processing, and then divided into three groups rehydrated with either saline solution (0.9%), phosphate-buffered saline (PBS), or minimum essential medium (MEM). Flexural stiffness, tensile stiffness, and gliding friction were evaluated before and after allograft processing. The flexural moduli in both fibrous and fibrocartilaginous regions of the tendons were measured. After lyophilization and reconstitution, the flexural moduli of both the fibrocartilaginous and non-fibrocartilaginous regions of the tendons increase significantly in the saline and MEM groups (p < 0.05). Compared to the saline and MEM groups, the flexural moduli of the fibrocartilaginous and non-fibrocartilaginous regions of tendons rehydrated with PBS are significantly lower (p < 0.05). Tensile moduli of rehydrated tendons are significantly lower than those of fresh tendons for all groups (p < 0.05). The gliding friction of rehydrated tendons is significantly higher than that of fresh tendons in all groups (p < 0.05). There is no significant difference in either tensile moduli or gliding friction between tendons treated with different rehydration solutions. These results demonstrate that allograft reconstitution can be optimized through careful selection of hydrating solution and that PBS could be a better choice as the impact on flexural properties is lower.

The objective of this study was to examine the effect of pulling angle on time-zero mechanical properties of intact infraspinatus tendon or infraspinatus tendon repaired with the modified Mason-Allen technique in a canine model in vitro. Thirty-six canine shoulder samples were used. Twenty intact samples were randomly allocated into functional pull (135°) and anatomic pull (70°) groups (n = 10 per group). The remaining sixteen infraspinatus tendons were transected from the insertion and repaired using the modified Mason-Allen technique before being randomly allocated into functional pull or anatomic pull groups (n = 8 per group). Load to failure testing was performed on all specimens. The ultimate failure load and ultimate stress of the functional pulled intact tendons were significantly lower compared with anatomic pulled tendons (1310.2 ± 167.6 N vs. 1687.4 ± 228.2 N, p = 0.0005: 55.6 ± 8.4 MPa vs. 67.1 ± 13.3 MPa, p = 0.0334). For the tendons repaired with the modified Mason-Allen technique, no significant differences were observed in ultimate failure load, ultimate stress or stiffness between functional pull and anatomic pull groups. The variance of pulling angle had a significant influence on the biomechanical properties of the rotator cuff tendon in a canine shoulder model in vitro. Load to failure of the intact infraspinatus tendon was lower at the functional pulling position compared to the anatomic pulling position. This result indicates that uneven load distribution across tendon fibers under functional pull may predispose the tendon to tear. However, this mechanical character is not presented after rotator cuff repair using the modified Mason-Allen technique.

Purpose: The aim of the study was to test flexor tendon repair with a novel hollow mesh suture augmentation served as a centre core cable [Triple-C (Tri-C)] in an in vitro study using a turkey model. Methods: Forty long digits from white turkey feet were divided into the following four groups based on repair techniques: Group 0, intact tendon without repair; Group 1, modified Kessler (MK) repair only (MKo); Group 2, MK repair plus Tri-C (MK ​+ ​Tri-C); and Group 3, MK repair plus an additional outside knot plus Tri-C (MK-2knots ​+ ​Tri-C). Mechanical evaluations were performed for all groups. Results: The frictions of the two groups with Tri-C were not significantly different than those of the MKo group. The ultimate tensile strength of the MK ​+ ​Tri-C group was not significantly different from that of the MKo group or the MK-2knots ​+ ​Tri-C group. In contrast, the MK-2knots ​+ ​Tri-C group had a significantly greater ultimate tensile strength compared with that of the MKo group. Forces at 2-mm gap formation in the groups with Tri-C were significantly stronger than that of MK alone. Conclusion: Our data have demonstrated that MK repair augmented with the centre hollow mesh suture increased failure strength without inducing increased friction. The translational potential of this article: Our study elucidates that a Tri-C augmentation designed in this study can achieve mechanical enhancements without increasing the repaired tendon friction. Hence, this novel technique has potential biological validity and clinical application. Keywords: Centre core cable, Flexor tendon, Mechanical evaluations, Repair

The purpose of this study is to investigate the attenuation effect of the pile barrier in blocking seismic surface waves by using theoretical and numerical methods. First, we derive the dispersion characteristics of pile barriers embedded in soil from the perspective of periodicity theory to explain that such periodic barriers can attenuate seismic surface waves when the main frequencies fall into the band gaps of the pile barrier. Second, the dispersion characteristics of periodic barriers composed of different inclusions are discussed, and it is suggested preliminarily that scatters with low stiffness and low density are more conductive to mitigate low-frequency surface waves. Third, a three-dimensional transmission calculation model is also developed to illustrate that the attenuation zone of a finite number of piles is consistent with the surface wave band gap. Finally, transient analysis of the periodic pile barriers is performed to validate the block effects on seismic surface waves. The numerical results show that the frequency band gaps of multi-row pile barriers are in accordance with the frequency band gaps of the surface wave in theory, which can greatly mitigate surface ground vibration. The pile spacing, number of piles, and pile length are the key parameters that can affect the width of attenuation zones of the periodic barriers by an appropriate design.

Abstract Background Fibroblast behavior and cell-matrix interactions of cells from normal and idiopathic carpal tunnel syndrome (CTS) subsynovial connective tissue (SSCT) with and without Triamcinolone Acetonide (TA) were compared in this study. A cell-seeded gel contraction model was applied to investigate the effect of steroid treatment on SSCT fibroblast gene expression and function. Methods SSCT cells were obtained from CTS patients and fresh cadavers. Cells were isolated by mechanical and collagenase digestion. Collagen gels (1 mg/ml) were prepared with SSCT cells (1 × 106/mL). A sterile Petri dish with a cloning ring in the center was prepared. The area between the ring and outer dish was filled with cell-seeded collagen solution and gelled for 1 h. The gel was released from the outer way of the petri dish to allow gel contraction. Cell seeded gels were treated with 10 M triamcinolone acetonide (TA) or vehicle (DMSO) in modified MEM. Every 4 h for 3 days the contracting gels were photographed and areas calculated. Duplicate contraction tests were performed with each specimen, and the averages were used in the analyses, which were conducted using two-factor analysis of variance in a generalized linear model framework utilizing generalized estimating equations (GEE) to account for the correlation between samples. The contraction rate was determined by the area change over time, and the decay time constant was calculated. A customized mechanical test system was used to determine gel stiffness and tensile strength. Gene expression was assessed using Human Fibrosis and Cell Motility PCR arrays. Results TA-treated gels had a significantly higher contraction rate, tensile strength and stiffness than the untreated gels. Proteinases involved in remodeling had increased expression in TA-treated gels of the patient group. Pro-fibrotic genes and ECM regulators, such as TGF-β, collagens and integrins, were down-regulated by TA, indicating that TA may work in part by decreasing fibrotic gene expression. Conclusions This study showed that TA affects cell-matrix interaction and suppresses fibrotic gene expression in the SSCT cells of CTS patients.

Study DesignExperimental Animal Model.PurposeThe aim of our study was to validate a pure bilateral ovariectomy (OVX) female New Zealand white rabbit model of postmenopausal osteoporosis utilizing animal-sparing in vivo techniques for evaluating bone mineral density (BMD). We also sought to demonstrate that bilateral OVX in female New Zealand white rabbits can produce diminished BMD in the spinal column and simulate osteoporosis, without the need for adjuvant chemotherapeutic agents (i.e., no additional glucocorticosteroids or other drugs were used for stimulating accelerated BMD loss), which can be assessed by in vivo BMD testing.Overview of LiteratureMultiple animal models of postmenopausal osteoporosis have been described. Rat ovariectomy models have been successful, but are limited by rats' inability to achieve true skeletal maturity and a slight morphology that limits surgical instrumentation. Rabbit models have been described which do not have these limitations, but previous models have relied on adjunctive steroid therapy to achieve osteoporosis and have required animal sacrifice for bone mineral density assessment.MethodsThirty-six skeletally mature female rabbits underwent bilateral OVX. BMD was measured using dual-energy X-ray absorptiometry on the metaphysis of the proximal tibia and distal femur, at baseline and 17 weeks postoperatively.ResultsMean BMD values were significantly reduced by 21.9% (p

Due to the long-term operation of power grid and the interference of external uneven electric field environment, silicone rubber insulators are prone to aging and scaling, and their hydrophobicity and external insulation performance are easily affected. In order to solve this problem, a kind of silicone rubber insulator outer surface cleaning and repairing agent was prepared with self-made composite solvent and silicone as the main raw materials, supplemented by catalyst, surfactant and other additives. So as to achieve the dual effect of efficient cleaning and aging repair, improve its hydrophobicity and prolong its service life. Through hardness test, hydrophobicity test, SEM test, FT-IR test, EDS test, mechanical property test and aging test characterization, and comparing the cleaning effect of different cleaning methods, it is found that the cleaning effect of cleaning repair agent is the best. In addition, it is found that the hydrophobicity of insulator has been greatly improved, from HC4 to HC1, and the mechanical properties have also been improved. This is because after using the cleaning and repairing agent, the powdered layer on the insulator surface is removed, and more hydrophobic methylene (Si–(CH _3 ) _2 ) and methylene (Si–(CH _3 ) _3 ) are attached to the insulator surface, which reduces the -OH binding force between the insulator surface and water molecules. In addition, through the observation of the surface and cross-section micro morphology, it is found that the surface roughness of the insulator is greatly reduced and the micro cracks disappear after using the cleaning and repairing agent, which highlights a certain repairing effect. Finally, the aging test also shows that the cleaning repair layer has a certain durability.The results show that the cleaning and repairing agent can effectively clean and repair the aged insulator, improve its anti- pollution flashover ability and prolong the service life of silicone rubber insulator.

The shield building of AP1000 was designed to protect the steel containment vessel of the nuclear reactor. Therefore, the safety and integrity must be ensured during the plant life in any conditions such as an earthquake. The aim of this paper is to study the effect of water in the water tank on the response of the AP1000 shield building when subjected to three-dimensional seismic ground acceleration. The smoothed particle hydrodynamics method (SPH) and finite element method (FEM) coupling method is used to numerically simulate the fluid and structure interaction (FSI) between water in the water tank and the AP1000 shield building. Then the grid convergence of FEM and SPH for the AP1000 shield building is analyzed. Next the modal analysis of the AP1000 shield building with various water levels (WLs) in the water tank is taken. Meanwhile, the pressure due to sloshing and oscillation of the water in the gravity drain water tank is studied. The influences of the height of water in the water tank on the time history of acceleration of the AP1000 shield building are discussed, as well as the distributions of amplification, acceleration, displacement, and stresses of the AP1000 shield building. Research on the relationship between the WLs in the water tank and the response spectrums of the structure are also taken. The results show that the high WL in the water tank can limit the vibration of the AP1000 shield building and can more efficiently dissipate the kinetic energy of the AP1000 shield building by fluid-structure interaction.

With the widespread use of high-resolution ultrasonography, ultrasonic examination has been shown to be useful as a diagnostic method for carpal tunnel syndrome. The main advantages of ultrasonography are that it is simple, quick, non-invasive, and economical. Another advantage is that tissue dynamics can be observed with real-time imaging. In recent reports, it has been shown that ultrasonic examination can provide similar diagnostic accuracy as nerve conduction study in the diagnosis of carpal tunnel syndrome. It has been expected that ultrasound demand in daily medical care will continue to increase. Ultrasonography in carpal tunnel syndrome shows an enlarged median nerve in proximal carpal tunnel, thickening of the flexor retinaculum, and edema around flexor tendons in cross-sectional images. In addition, with the introduction of new technologies such as ultrasonic elastography and speckle tracking, it has become possible to quantify dynamics and material property changes of nerves, tendons, and their surrounding structures. In this review, we describe recent advancements of carpal tunnel syndrome diagnosis based on ultrasound dynamic images, and discuss its pathology.

Tendon injuries are among the most common and severe hand injuries with a high demand for functional recovery. Stem cells have been identified and isolated from different species and a variety of tissues for the sake of regenerative medicine. Recently, turkey has been suggested as a potential new large animal model for flexor tendon-related research. However, turkey tissue-specific stem cells have not been investigated. Here, we presented the isolation and verification of tendon-derived stem cells (TDSCs) from 6- to 8-month-old heritage-breed turkey. TDSCs were isolated from turkey flexor tendon by plating nucleated cells at the determined optimal density. Approximately 4% of the nucleated cells demonstrated clonogenicity, high proliferation rate, and trilineage differentiation potential after induction culturing. These cells expressed surface antigens CD90, CD105, and CD44, but did not express CD45. There was a high level of gene expression of tenogenic markers in TDSCs, including mohawk, collagen type I, tenascin C, and elastin. Turkey TDSCs also expressed transcription factors PouV, Nanog, and Sox2, which are critically involved in the regulation of stemness. The successful isolation of tendon-derived stem cells from turkey was beneficial for future studies in tendon tissue engineering and would help in the development of new treatment for tendon diseases using this novel animal model.

The flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP) are critical for finger flexion. Although research has recently focused on these tendons' coactivity, their contributions in different tasks remain unclear. This study created a novel simultaneous approach to investigate the coactivity between the tendons and to clarify their contributions in different tasks.Ten human cadaveric hands were mounted on our custom frame with the FDS and FDP of the third finger looped through a mechanical pulley connected to a force transducer. Joint range of motion, tendon excursion and loading force were recorded during individual joint motion and free joint movement from rest to maximal flexion. Each flexor tendon's moment arm was then calculated.In individual motions, we found that the FDP contributed more than the FDS in proximal interphalangeal (PIP) joint motion, with an overall slope of 1.34 and all FDP-to-FDS excursion (P/S) ratios greater than 1.0 with force increase. However, the FDP contributed less than the FDS in metacarpophalangeal (MCP) joint motion, with an overall slope of 0.95 and P/S ratios smaller than 1.0 throughout the whole motion except between 1.9% and 13.1% force. In free joint movement, the FDP played a greater role than the FDS, with an overall ratio of 1.37 and all P/S ratios greater than 1.0.The new findings include differences in finger performance and excursion amounts between the FDS and FDP throughout flexion. Such findings may provide the basis for new hand models and treatments.

Although the margin convergence (MC) technique has been recognized as an option for rotator cuff repair, little is known about the biomechanical effect on repaired rotator cuff muscle, especially after supplemented footprint repair. The purpose of this study was to assess the passive stiffness changes of the supraspinatus (SSP) muscle after MC techniques using shear wave elastography (SWE). A 30 × 40-mm U-shaped rotator cuff tear was created in 8 cadaveric shoulders. Each specimen was repaired with 6 types of MC technique (1-, 2-, 3-suture MC with/without footprint repair, in a random order) at 30° glenohumeral abduction. Passive stiffness of four anatomical regions in the SSP muscle was measured based on an established SWE method. Data were obtained from the SSP muscle at 0° abduction under 8 different conditions: intact (before making a tear), torn, and postoperative conditions with 6 techniques. MC techniques using 1-, or 2-suture combined with footprint repair showed significantly higher stiffness values than the intact condition. Passive stiffness of the SSP muscle was highest after a 1-suture MC with footprint repair for all regions when compared among all repair procedures. There was no significant difference between the intact condition and a 3-suture MC with footprint repair. MC techniques with single stitch and subsequent footprint repair may have adverse effects on muscle properties and tensile loading on repair, increasing the risk of retear of repairs. Adding more MC stitches could reverse these adverse effects.

A new elasto-plastic constitutive model for jointed rock mass, which can consider the persistence ratio in different visual angle and anisotropic increase of plastic strain, is proposed. The proposed the yield strength criterion, which is anisotropic, is not only related to friction angle and cohesion of jointed rock masses at the visual angle but also related to the intersection angle between the visual angle and the directions of the principal stresses. Some numerical examples are given to analyze and verify the proposed constitutive model. The results show the proposed constitutive model has high precision to calculate displacement, stress and plastic strain and can be applied in engineering analysis.

Short-segment pedicle screw instrumentation (SSPI) is used for unstable burst fractures to correct deformity and stabilize the spine for fusion. However, pedicle screw loosening, pullout, or breakage often occurs due to the large moment applied during spine motion, leading to poor outcomes. The purpose of this study was to test the ability of a newly designed device, the Trans-Endplate Pedicle Pillar System (TEPPS), to enhance SSPI rigidity and decrease the screw bending moment with a simple posterior approach.Six human cadaveric spines (T11-L3) were harvested. A burst fracture was created at L1, and the SSPI (Moss Miami System) was used for SSPI fixation. Strain gauge sensors were mounted on upper pedicle screws to measure screw load bearing. Segmental motion (T12-L2) was measured under pure moment of 7.5 Nm. The spine was tested sequentially under 4 conditions: intact; first SSPI alone (SSPI-1); SSPI+TEPPS; and second SSPI alone (SSPI-2).SSPI+TEPPS increased fixation rigidity by 41% in flexion/extension, 28% in lateral bending, and 37% in axial rotation compared with SSPI-1 (P

An increased bone mineral density (BMD) in the proximity to tendon insertion can improve rotator cuff repair and healing. However, how a decrease of BMD in the humeral head affects the biomechanical properties of the rotator cuff tendon is still unclear. Previous studies have demonstrated ovariectomy in animals to lead to osteoporosis and decreased BMD, and Teriparatide (PTH) administration to improve BMD and strength of bone. This study aimed to explore the correlation between humeral head BMD and infraspinatus (ISP) tendon insertion strength, and if an increase in bone quantity of the humeral head can improve the strength of the rotator cuff.Eighteen New England white rabbits were divided into the 3 groups: Control, Ovariectomy-Saline (OVX-Saline), and Ovariectomy-PTH (OVX-PTH). The OVX-Saline group and the OVX-PTH were administered daily saline and Teriparatide injections for 8 weeks starting at 17 weeks of OVX. BMD of the humeral head was measured, the ISP tendon failure load was tested and the failure stress was calculated. One specimen from each group was used for histological analysis. Linear regression analysis was used to derive equations for the BMD and failure stress.Significant differences were observed in the measured humeral head BMD of the Control and OVX-PTH groups compared to the OVX-Saline group (P = 0.0004 and P = 0.0024, respectively). No significant difference was found in failure stress among the three groups, but an expected trend with the control group and OVX-PTH group presenting higher failure strength compared to the OVX-Saline group. BMD at the humeral head showed a positive linear correlation with stress (r2 = 0.54). Histology results showed the superiority in OVX-PTH group ISP enthesis compared to the OVX-Saline group.Bone loss of the humeral head leads to decreased tendon/bone insertion strength of the infraspinatus tendon enthesis. Teriparatide administration can increase bone density of the humeral head and may improve the mechanical properties of the infraspinatus tendon enthesis.

The major concern of using a large animal model to study rotator cuff repair is the high rate of repair retears. The purpose of this study was to test a non-weight-bearing (NWB) canine model for rotator cuff repair research.First, in the in vitro study, 18 shoulders were randomized to 3 groups. 1) Full-width transections repaired with modified Mason-Allen sutures using 3-0 polyglactin suture, 2) Group 1 repaired using number 2 (#2) polyester braid and long-chain polyethylene suture, and 3) Partial-width transections leaving the superior 2 mm infraspinatus tendon intact without repair. In the in vivo study of 6 dogs, the infraspinatus tendon was partially transected as the same as the in vitro group 3. A radial neurectomy was performed to prevent weight bearing. The operated limb was slung in a custom-made jacket for 6 weeks.In the in vitro study, mean ultimate tensile load and stiffness in Group 2 were significantly higher than Group 1 and 3 (p

Although trigger finger is a relatively common hand disorder, its exact cause remains unknown. Whether the etiology of the abnormality resides in the tendon or in the pulley continues debate. The purpose of this review is to summarize what is known about the clinical and biomechanical presentation of trigger finger. While the A1 pulleys are more accessible for examination than the flexor tendons during surgery and have been more extensively studied, it should not yet be assumed that the tendons are any less responsible for the entrapment symptom. Previous assessments of these tissues include testing of their compliance, friction coefficient, and contact angle. Kinematic and kinetic performance of trigger fingers has been evaluated in vivo. Thickening and changes in gene expression have also been identified in trigger finger tendons. Further investigation into the role of flexor tendons in trigger finger should be performed to facilitate the understanding of the etiology and mechanism of trigger finger development. Future studies could incorporate non-invasive medical imaging in order to understand the appearance and material properties of the involved pulley and tendons, and to combine these characteristics with finger kinematics. Furthermore, understanding the mechanism of biologic adaptations of the A1 pulley and the flexor tendons in response to the mechanical loading might be helpful in providing clues and evidence for effective, novel treatment for trigger finger.

Carpal tunnel syndrome (CTS) is an idiopathic disease that results from increased fibrosis of the subsynovial connective tissue (SSCT). A recent study found overexpression of both transforming growth factor-β (TGF-β) and connective tissue growth factor (CTGF) in the SSCT of CTS patients. This study investigated TGF-β and CTGF expression in a rabbit model of CTS, in which SSCT fibrosis is induced by a surgical injury. Levels of TGF-β1 and CTGF at 6, 12, 24 weeks after injury were determined by immunohistochemistry A significant increase in TGF-β1 and a concomitant significant increase in CTGF were found at 6 weeks, in addition to higher cell density compared to normal (all p

LeuT-like fold Na-dependent secondary active transporters form a large family of integral membrane proteins that transport various substrates against their concentration gradient across lipid membranes, using the free energy stored in the downhill concentration gradient of sodium ions. These transporters play an active role in synaptic transmission, the delivery of key nutrients, and the maintenance of osmotic pressure inside the cell. It is generally believed that binding of an ion and/or a substrate drives the conformational dynamics of the transporter. However, the exact mechanism for converting ion binding into useful work has yet to be established. Using a multi-dimensional path sampling (string-method) followed by all-atom free energy simulations, we established the principal thermodynamic and kinetic components governing the ion-dependent conformational dynamics of a LeuT-like fold transporter, the sodium/benzyl-hydantoin symporter Mhp1, for an entire conformational cycle. We found that inward-facing and outward-facing states of Mhp1 display nearly the same free energies with an ion absent from the Na2 site conserved across the LeuT-like fold transporters. The barrier separating an apo-state from inward-facing or outward-facing states of the transporter is very low, suggesting stochastic gating in the absence of ion/substrate bound. In contrast, the binding of a Na2 ion shifts the free energy stabilizing the outward-facing state and promoting substrate binding. Our results indicate that ion binding to the Na2 site may also play a key role in the intracellular thin gate dynamics modulation by altering its interactions with the transmembrane helix 5 (TM5). The Potential of Mean Force (PMF) computations for a substrate entrance displays two energy minima that correspond to the locations of the main binding site S1 and proposed allosteric S2 binding site. However, it was found that substrate's binds to the site S1 ∼5 kcal/mol more favorable than that to the site S2 for all studied bound combinations of ions and a substrate.

The purpose of this study was to investigate the role of lubricin on the gliding resistance of intrasynovial tendons by comparing lubricin knockout, heterozygous, and wild type mice. A total of thirty-six deep digital flexor (DDF) tendons in the third digits of each hind paw from eighteen adult mice were used, including six lubricin knockout mice (Prg4 -/-), six heterozygous mice (Prg4 +/-), and six wild type mice (Prg4 +/+). The tendon gliding resistance was measured using a custom-made device. Tendon structural changes were evaluated by scanning electron and light microscopy. The gliding resistance of intrasynovial tendons from lubricin knockout mice was significantly higher than the gliding resistance of either wild type or heterozygous mice. The surface of the lubricin knockout tendons appeared to be rougher, compared to the wild type and heterozygous tendons. Synovial hyperplasia was found in the lubricin knockout mice. Cartilage-like tissue was found in the tendon and pulley of the lubricin knockout mice. Our findings confirm the importance of lubricin in intrasynovial tendon lubrication. This knockout model may be useful in determining the effect of lubricin on tendon healing and the response to injury.

BACKGROUND: Abnormal posture and spinal mobility have been demonstrated to cause functional impairment in the quality of life, especially in the postmenopausal osteoporotic population. Most of the literature studies focus on either thoracic kyphosis or lumbar lordosis, but not on the change of the entire spinal alignment. Very few articles reported the spinal alignment of Chinese people. The purpose of this study was threefold: to classify the spinal curvature based on the classification system defined by Satoh consisting of the entire spine alignment; to identify the change of trunk mobility; and to relate spinal curvature to balance disorder in a Chinese population. METHODOLOGY/PRINCIPAL FINDINGS: 450 osteoporotic volunteers were recruited for this study. Spinal range of motion and global curvature were evaluated noninvasively using the Spinal-Mouse® system and sagittal postural deformities were characterized. RESULTS: We found a new spine postural alignment consisting of an increased thoracic kyphosis and decreased lumbar lordosis which we classified as our modified round back. We did not find any of Satoh's type 5 classification in our population. Type 2 sagittal alignment was the most common spinal deformity (38.44%). In standing, thoracic kyphosis angles in types 2 (58.34°) and 3 (58.03°) were the largest and lumbar lordosis angles in types 4 (13.95°) and 5 (-8.61°) were the smallest. The range of flexion (ROF) and range of flexion-extension (ROFE) of types 2 and 3 were usually greater than types 4 and 5, with type 1 being the largest. CONCLUSIONS/SIGNIFICANCE: The present study classified and compared for the first time the mobility, curvature and balance in a Chinese population based on the entire spine alignment and found types 4 and 5 to present the worst balance and mobility. This study included a new spine postural alignment classification that should be considered in future population studies.