Force Recovery Research Articles

Phase evolution based thermomechanical crack closure mechanism of shape memory polymers

In this article, the thermomechanical fracture responses of shape memory polymers (SMPs) under two common stress free- strain recovery and fixed strain- stress recovery loading cycles are investigated. The shape memory properties of cracked SMPs for both single and mixed fracture modes are examined. The effect of phase transformation on the fracture parameters of the material is evaluated by the extended finite element method (XFEM). In addition, the fracture behavior is studied when the crack is created during the thermomechanical process. The results show that the initially cracked SMPs can fully preserve the shape memory property for both stress free- strain recovery and fixed strain- stress recovery cycles. Moreover, as a promising application, SMPs can be well employed in self-healing materials due to complete closure of the crack at the end of the shape recovery cycle. In cases where a crack is created in the midst of the fixed strain- stress recovery thermomechanical process, it is observed that the performance of the structure in providing desired reaction forces is reduced by increase of the crack length. Nevertheless, the presence of compressive forces in the initial steps of the force recovery cycle may potentially contribute to crack healing if additive healing agents are employed.

Sensitivity studies of ANFIS based force recovery technique towards prediction of aerodynamic load

Accelerometer force balance (AFB), in conjunction with various force prediction methodologies, has been used in hypersonic flow regime. Present studies focus on its ability to capture small and large alterations in the force and moment coefficients. For this objective, shock tunnel experiments are conducted on a bi-conic model without and with hemispherical or sharp aerospike. A three component AFB is equipped to measure acceleration responses during the experiments. Adaptive Neuro Fuzzy Inference System (ANFIS) is employed herein for the force recovery. Aerodynamic coefficients obtained from ANFIS are noticed to have encouraging match with the AFB theory. It has been shown here that, AFB and recently developed ANFIS based force recovery methodology can precisely predict as small as 6.3% and as large as 38% change in the force along with its temporal variation. Hence, this study strengthens the use of a soft computing technique like ANFIS for predicting steady state and temporal variations of aerodynamic coefficients during shock tunnel testing of hypersonic configurations.

Functional recovery from eccentric injury is maintained in sarcopenic mouse muscle.

Eccentric contractions induce muscle damage (EIMD) that compromises muscle function. Poor recovery from EIMD has been suggested to be a contributor to the decline in muscle function evident in sarcopenia, but it is unclear which aspects of muscle function are more susceptible to disruption by EIMD in old versus young muscle. The purpose of this study was to determine the extent of impairment in contractile function (force, fatigue, tetanus and twitch kinetics) during the recovery from EIMD in very old (VO) mice compared to young adult (YA). Male CB6F1 were obtained from National Institure of Aging colony. VO mice were 29-31 months of age, and YA mice were 7-9 months of age. The plantarflexor muscles were subjected to 20 eccentric contractions in vivo to induce injury (EIMD). Changes in tetanic force and kinetics were assessed before EIMD, immediately after EIMD and 3 days after EIMD (3dEIMD). Force-frequency and rates of fatigue were assessed 3d-EIMD and compared with baseline. Histological analysis was conducted in injured and non-injured contralateral gastrocnemius muscle. There was a greater loss in isometric tetanic force immediately following EIMD in VO compared with YA (-31.6% ± 10.4 vs. -21.7% ± 6.0, P < 0.05). At 3d-EIMD, the rate of contraction of tetanus began to recover in VO, but not in YA (20.8% vs. -6.8%, P < 0.05), whereas the extent of recovery of force tended to be greater in VO than YA (39.3% vs. 17.1%, P = 0.08) when compared with tetanic function immediately after injury. Compared with function pre-injury (baseline), VO and YA had similar deficits in tetanic force (-7.3% ± 5.3 vs. -9.2% ± 6.0, respectively) and kinetics at Day 3. Twitch kinetics (rate of relaxation) recovered faster in VO compared with YA. The rate of muscle fatigue was similar to baseline values, with VO continuing to be more fatigue resistant than YA 3d-EIMD. There were no detectable differences in muscle mass or myofibre cross-sectional area despite continued deficits in force following EIMD in either age group. Despite clear functional deficits and greater susceptibility to injury, aged sarcopenic muscle exhibited a similar ability to recover contractile function to younger muscle following EIMD. In addition, neither age group showed accelerated muscle fatigue in the recovery phase after EIMD; thus, sarcopenic mouse muscles do not appear to be more susceptible to long-term functional impairment than young healthy muscles.

Effect of burst ratio on flow separation control using a dielectric barrier discharge plasma actuator at Reynolds number 2.6 × 105

In this study, the effect of the burst ratio (BR) on flow separation control using an alternating-current dielectric barrier discharge plasma actuator (DBDPA) was investigated. The effects of BR on the lift force on the NACA0015 airfoil were quantitatively evaluated by force measurements, and those on the flow field were measured by particle image velocimetry (PIV) and Schlieren visualisation. The force measurements showed that the recovery of the lift force decreased as BR increased, indicating that the flow separation control effect of the DBDPA decreased as BR increased. The PIV measurements showed that the temporal variation in vorticity was smaller at BR = 80% than at BR = 20% and that the vorticity did not change periodically at BR = 100%. Schlieren visualisation showed that DBDPA-induced flow produced a density gradient near the DBDPA electrode; the gradient was periodically observed and was found to be proportional to BR. In contrast, the density gradient in the separated shear layer varied at the end of each burst waveform, and the degree of variation decreased as BR increased. In addition, the root mean square value of the Schlieren signal intensity in the separated shear layer decreased with increasing BR. This result suggests that not only the strength and frequency of the disturbance input of the DBDPA but also the switching timing of the disturbance input are important for producing vorticity and thereby ensuring flow control.

Measurement Technique for Ideal Selection of Sensors and Accurate Force Recovery on Aerodynamic Models

Measurement Technique for Ideal Selection of Sensors and Accurate Force Recovery on Aerodynamic Models

The effect of autologous repair and voluntary wheel running on force recovery in a rat model of volumetric muscle loss.

What is the central question of this study? Following large traumatic loss of muscle tissue (volumetric muscle loss; VML), permanent functional and cosmetic deficits present themselves and regenerative therapies alone have not been able to generate a robust regenerative response: how does the addition of rehabilitative therapies affects the regenerative response? What is the main finding and its importance? Using exercise along with autologous muscle repair, we demonstrated accelerated muscle force recovery response post-VML. The accentuated force recovery 2weeks post-VML would allow patients to return home sooner than allowed with current therapies. Skeletal muscle can regenerate from damage but is overwhelmed with extreme tissue loss, known as volumetric muscle loss (VML). Patients suffering from VML do not fully recover force output in the affected limb. Recent studies show that replacement tissue (i.e., autograph) into the VML defect site plus physical activity show promise for optimizing force recovery post-VML. The purpose of this study was to measure the effects of autologous repair and voluntary wheel running on force recovery post-VML. Thirty-two male Sprague-Dawley rats had 20% of their left tibialis anterior (LTA) excised then replaced and sutured into the intact muscle (autologous repair). The right tibialis anterior (RTA) acted as the contralateral control. Sixteen rats were given free access to a running wheel (Wheel) whereas the other 16 remained in a cage with the running wheel locked (Sed). At 2 and 8weeks post-VML, the LTA underwent force testing; then the muscle was removed and morphological and gene expression analysis was conducted. At 2weeks post-injury, normalized LTA force was 58% greater in the Wheel group compared to the Sed group. At 8weeks post-VML, LTA force was similar between the Wheel and Sed groups but was still lower than the uninjured RTA. Gene expression analysis at 2weeks post-VML showed the wheel groups had lower mRNA content of interleukin (IL)-1β, IL-6 and tumour necrosis factor α compared to the Sed group. Overall, voluntary wheel running promoted early force recovery, but was not sufficient to fully restore force. The accentuated early force recovery is possibly due to a more pro-regenerative microenvironment.

Muscle Precursor Cells Enhance Functional Muscle Recovery and Show Synergistic Effects With Postinjury Treadmill Exercise in a Muscle Injury Model in Rats

Background: Skeletal muscle injuries represent a major concern in sports medicine. Cell therapy has emerged as a promising therapeutic strategy for muscle injuries, although the preclinical data are still inconclusive and the potential clinical use of cell therapy has not yet been established. Purpose: To evaluate the effects of muscle precursor cells (MPCs) on muscle healing in a small animal model. Study Design: Controlled laboratory study. Methods: A total of 27 rats were used in the study. MPCs were isolated from rat (n = 3) medial gastrocnemius muscles and expanded in primary culture. Skeletal muscle injury was induced in 24 rats, and the animals were assigned to 3 groups. At 36 hours after injury, animals received treatment based on a single ultrasound-guided MPC (105 cells) injection (Cells group) or MPC injection in combination with 2 weeks of daily exercise training (Cells+Exercise group). Animals receiving intramuscular vehicle injection were used as controls (Vehicle group). Muscle force was determined 2 weeks after muscle injury, and muscles were collected for histological and immunofluorescence evaluation. Results: Red fluorescence–labeled MPCs were successfully transplanted in the site of the injury by ultrasound-guided injection and were localized in the injured area after 2 weeks. Transplanted MPCs participated in the formation of regenerating muscle fibers as corroborated by the co-localization of red fluorescence with developmental myosin heavy chain (dMHC)–positive myofibers by immunofluorescence analysis. A strong beneficial effect on muscle force recovery was detected in the Cells and Cells+Exercise groups (102.6% ± 4.0% and 101.5% ± 8.5% of maximum tetanus force of the injured vs healthy contralateral muscle, respectively) compared with the Vehicle group (78.2% ± 5.1%). Both Cells and Cells+Exercise treatments stimulated the growth of newly formed regenerating muscles fibers, as determined by the increase in myofiber cross-sectional area (612.3 ± 21.4 µm2 and 686.0 ± 11.6 µm2, respectively) compared with the Vehicle group (247.5 ± 10.7 µm2), which was accompanied by a significant reduction of intramuscular fibrosis in Cells and Cells+Exercise treated animals (24.2% ± 1.3% and 26.0% ± 1.9% of collagen type I deposition, respectively) with respect to control animals (40.9% ± 4.1% in the Vehicle group). MPC treatment induced a robust acceleration of the muscle healing process as demonstrated by the decreased number of dMHC-positive regenerating myofibers (enhanced replacement of developmental myosin isoform by mature myosin isoforms) (4.3% ± 2.6% and 4.1% ± 1.5% in the Cells and Cells+Exercise groups, respectively) compared with the Vehicle group (14.8% ± 13.9%). Conclusion: Single intramuscular administration of MPCs improved histological outcome and force recovery of the injured skeletal muscle in a rat injury model that imitates sports-related muscle injuries. Cell therapy showed a synergistic effect when combined with an early active rehabilitation protocol in rats, which suggests that a combination of treatments can generate novel therapeutic strategies for the treatment of human skeletal muscle injuries. Clinical Relevance: Our study demonstrates the strong beneficial effect of MPC transplant and the synergistic effect when the cell therapy is combined with an early active rehabilitation protocol for muscle recovery in rats; this finding opens new avenues for the development of effective therapeutic strategies for muscle healing and clinical trials in athletes undergoing MPC transplant and rehabilitation protocols.

Biofabricating murine and human myo‐substitutes for rapid volumetric muscle loss restoration

The importance of skeletal muscle tissue is undoubted being the controller of several vital functions including respiration and all voluntary locomotion activities. However, its regenerative capability is limited and significant tissue loss often leads to a chronic pathologic condition known as volumetric muscle loss. Here, we propose a biofabrication approach to rapidly restore skeletal muscle mass, 3D histoarchitecture, and functionality. By recapitulating muscle anisotropic organization at the microscale level, we demonstrate to efficiently guide cell differentiation and myobundle formation both in vitro and in vivo. Of note, upon implantation, the biofabricated myo‐substitutes support the formation of new blood vessels and neuromuscular junctions—pivotal aspects for cell survival and muscle contractile functionalities—together with an advanced muscle mass and force recovery. Altogether, these data represent a solid base for further testing the myo‐substitutes in large animal size and a promising platform to be eventually translated into clinical scenarios.

Enhanced cell survival and therapeutic benefits of IL-10-expressing multipotent mesenchymal stromal cells for muscular dystrophy

BackgroundMultipotent mesenchymal stromal cells (MSCs) are potentially therapeutic for muscle disease because they can accumulate at the sites of injury and act as immunosuppressants. MSCs are attractive candidates for cell-based strategies that target diseases with chronic inflammation, such as Duchenne muscular disease (DMD). We focused on the anti-inflammatory properties of IL-10 and hypothesized that IL-10 could increase the typically low survival of MSCs by exerting a paracrine effect after transplantation.MethodsWe developed a continuous IL-10 expression system of MSCs using an adeno-associated virus (AAV) vector. To investigate the potential benefits of IL-10 expressing AAV vector-transduced MSCs (IL-10-MSCs), we examined the cell survival rates in the skeletal muscles after intramuscular injection into mice and dogs. Systemic treatment with IL-10-MSCs derived from dental pulp (DPSCs) was comprehensively analyzed using the canine X-linked muscular dystrophy model in Japan (CXMDJ), which has a severe phenotype similar to that of DMD patients.ResultsIn vivo bioluminescence imaging analysis revealed higher retention of IL-10-MSCs injected into the hindlimb muscle of mice. In the muscles of dogs, myofiber-like tissue was formed after the stable engraftment of IL-10-MSCs. Repeated systemic administration of IL-10-DPSCs into the CXMDJ model resulted in long-term engraftment of cells and slightly increased the serum levels of IL-10. IL-10-hDPSCs showed significantly reduced expression of pro-inflammatory MCP-1 and upregulation of stromal-derived factor-1 (SDF-1). MRI and histopathology of the hDPSC-treated CXMDJ indicated the regulation of inflammation in the muscles, but not myogenic differentiation from treated cells. hDPSC-treated CXMDJ showed improved running capability and recovery in tetanic force with concomitant increase in physical activity. Serum creatine kinase levels, which increased immediately after exercise, were suppressed in IL-10-hDPSC-treated CXMDJ.ConclusionsIn case of local injection, IL-10-MSCs could maintain the long-term engraftment status and facilitate associated tissue repair. In case of repeated systemic administration, IL-10-MSCs facilitated the long-term retention of the cells in the skeletal muscle and also protected muscles from physical damage-induced injury, which improved muscle dysfunction in DMD. We can conclude that the local and systemic administration of IL-10-producing MSCs offers potential benefits for DMD therapy through the beneficial paracrine effects of IL-10 involving SDF-1.

Physical and thermo-mechanical properties of shape memory polyurethane containing reversible chemical cross-links

Orthodontic chains are one of the main parts of orthodontic braces. In this study, in order to obtain a suitable polymer for this application as well as troubleshoot the main drawbacks such as stress relaxation and water absorption, thermoplastic polyurethane (TPU) elastomers with various compositions were synthesized and characterized by Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) analyses. Mechanical properties of samples were evaluated by tensile, elasticity, and stress relaxation tests. According to the required properties for orthodontic chain application, PU2000-311 which contains reversible crosslinks, was selected as the most favorable sample among other pure samples. Moreover, to reduce the water absorption content of PU2000-311, its nanocomposite containing 1 wt% of silica nanoparticles was prepared via solution casting method. As water content angle and field emission scanning electron microscopy (FESEM) images illustrate, incorporation of 1 wt% of modified silica nanoparticles has increased PU2000-311-1S hydrophobicity. In vitro oral environment study showed crystability of samples has recovered great portion of relaxed force. Stress relaxation study indicated samples are applicable in oral temperature range and temperature changes have assisted recovery of relaxed force and reduced treatment period. Finally, shape memory study showed that optimum samples could recover 100% of their original shape.

Evaluation of bite force recovery in patients with maxillofacial fracture

The aim of this study was to measure the maximum voluntary bite force and recovery time in patients treated for different types of the maxillofacial fracture.Patients aged between 18 and 60 years, who received surgical treatment for a single isolated fracture of the maxillofacial structure, were included in this study. Healthy individuals without any maxillofacial abnormality were selected as the control group. Bite force (in kg) was measured at the first incisor tooth, bilaterally, prior to surgery and 2 weeks, 6 weeks, 3 months, and 6 months after surgery.Of 120 patients, 89 (74.17%) were male and 31 (25.83%) were female. Mean patient age (±SD) was 31.21 (±11.64) years. Bite forces relating to fractures of the zygomaticomaxillary complex (ZMC) with involvement of the arch and zygomaticofrontal suture reached normal levels after 6 weeks (from 3.89 (±1.11) to 10.82 (±1.29); p = 0.296 and from 4.20 (±0.93) to 10.70 (±1.70); p = 0.192, respectively). Bite force returned to normal after 3 months in fractures of the symphysis (from 2.05 (±0.97) to 12.18 (±0.77); p = 0.222), body (from 2.21 (±1.26) to 11.9 (±0.73); p = 0.750), angle (from 2.45 (±1.24) to 11.89 (±0.76); p = 0.769), condyle (from 2.45 (±1.27) to 11.25 (±0.82); p = 0.968), and ZMC with and without infraorbital rim involvement (from 3.83 (±0.93) to 11.92 (±0.84); p = 0.724 and from 3.7 (±1.21) to 12.03 (±0.82); p = 0.482, respectively).Patients with ZMC fracture involving the arch and zygomaticofrontal suture require fewer follow-ups in comparison with those with other maxillofacial fractures. Measurement of maximal bite force can help to evaluate dentofacial deformities before and after surgical treatment.

Effect of a Rotating and Swept Wingtip on Streamwise Gust Alleviation

Dynamic effects of wing planform changes are investigated with the goal of gust alleviation. Force measurements are done on a low-aspect-ratio high-angle-of-attack translating wing having a rectangular planform that incorporates a moving tip with in-plane rotation and sweep. To create streamwise gusts, the wing is towed in a water tank from constant motion to a new velocity that is 50% higher (“step-up”) or lower (“step-down”) through ramp distances of 1, 3, and 6 chords traveled. The tip panel is rotated inward for the step-up cases to lower the gust lift peaks and outward for step-down gusts to mitigate the lift lost. The actuation cases are compared using the unsteady with two reference geometries (pre- or post-gust wing shapes). In most cases, actuation yields better gust-force change for = 2 than = 4, due to the greater change in wing planform. The actuation timing also alters the details of the force recovery. Furthermore, an impulse metric shows that inward tip actuation can mitigate the gust-impulse change by as much as 38% and outward tip actuation by 84%. A superposition of the individual effects of the actuation and gust is tested against the cases of actuation during gusts.

RNU (Foxn1RNU-Nude) Rats Demonstrate an Improved Ability to Regenerate Muscle in a Volumetric Muscle Injury Compared to Sprague Dawley Rats

Products developed for skeletal muscle regeneration frequently incorporate allogeneic and xenogeneic materials to elicit a regenerative response to heal skeletal muscle wounds. To avoid graft rejection in preclinical studies, immunodeficient rodents are used. Whether the immunodeficiency alters the host response to the material in skeletal muscle has not been studied. In this study, we hypothesized that an allogeneic acellular skeletal muscle grafts implanted in an immunodeficient rat (RNU, Foxn1-deficient) would exhibit better new muscle fiber formation compared to grafts implanted in immunocompetent Sprague Dawley (SD) rats. Decellularized SD skeletal muscle matrix (DMM) was implanted in the gastrocnemius (N = 8 rats/group). 56 days after surgery, animal gait was examined and animals were euthanized. Muscle force was assessed and fiber number as well as immune cell infiltrate was measured by histomorphometry and immunohistochemistry. Animal gait and percent recovery of muscle force were unchanged in both groups, but newly regenerated muscle fibers increased in RNU rats. Macrophage staining for CD68 was higher in RNU rats than in SD rats. These data show differences in muscle regeneration between animal models using the same biomaterial treatment, but these differences could not be ascribed to the immune response. Overall, our data provide awareness that more studies are needed to understand how host responses to biomaterials differ based on the animal model used.

Single Cell Forces after Electroporation.

Exogenous high-voltage pulses increase cell membrane permeability through a phenomenon known as electroporation. This process may also disrupt the cell cytoskeleton causing changes in cell contractility; however, the contractile signature of cell force after electroporation remains unknown. Here, single-cell forces post-electroporation are measured using suspended extracellular matrix-mimicking nanofibers that act as force sensors. Ten, 100 μs pulses are delivered at three voltage magnitudes (500, 1000, and 1500 V) and two directions (parallel and perpendicular to cell orientation), exposing glioblastoma cells to electric fields between 441 V cm-1 and 1366 V cm-1. Cytoskeletal-driven force loss and recovery post-electroporation involves three distinct stages. Low electric field magnitudes do not cause disruption, but higher fields nearly eliminate contractility 2-10 min post-electroporation as cells round following calcium-mediated retraction (stage 1). Following rounding, a majority of analyzed cells enter an unusual and unexpected biphasic stage (stage 2) characterized by increased contractility tens of minutes post-electroporation, followed by force relaxation. The biphasic stage is concurrent with actin disruption-driven blebbing. Finally, cells elongate and regain their pre-electroporation morphology and contractility in 1-3 h (stage 3). With increasing voltages applied perpendicular to cell orientation, we observe a significant drop in cell viability. Experiments with multiple healthy and cancerous cell lines demonstrate that contractile force is a more dynamic and sensitive metric than cell shape to electroporation. A mechanobiological understanding of cell contractility post-electroporation will deepen our understanding of the mechanisms that drive recovery and may have implications for molecular medicine, genetic engineering, and cellular biophysics.

Comparison of Ultrasound-Guided Femoral and Infrapatellar Nerve Block Effects after Anterior Cruciate Ligament Repair Surgery

Background: There are various protocols for pain management after anterior cruciate ligament (ACL) reconstruction surgery. Objective: This study aimed to compare two blocking protocols, including femoral nerve block (FNB) and infrapatellar nerve block (IPNB) in terms of pain severity, patient satisfaction, and muscle force preservation. Materials and Methods: This single-blind clinical trial study investigated the patients who underwent elective knee arthroscopic ACL surgery randomly either by ultrasound-guided FNB or IPNB. Subsequently, the patients were evaluated 1, 3, 6, 12, and 24 h following NB for pain severity, patient satisfaction level, and muscle force. Results: The pain score (both at rest and in flexion) was significantly lower in the first three h after the intervention in the FNB group. Moreover, the mean score of the patients’ satisfaction in the first hours was significantly higher in the FNB group after the procedure. Additionally, the IPNB group obtained a significantly faster mean time required for the first dose of opioid request. The mean dose of used opioids over 24 h was significantly lower in the FNB group. There was a significant difference between the groups in terms of the muscle strength score within 24 h; moreover, the FNB group obtained a significantly greater delay in muscle recovery. Conclusion: The FNB is associated with greater pain relief and satisfaction in patients who underwent arthroscopic ACL reconstruction surgery, compared to the IFNB technique. However, a further delay in the recovery of quadriceps muscle force is evident in the FNB group.

Comparison of Ultrasound-Guided Femoral and Infrapatellar Nerve Block Effects after Anterior Cruciate Ligament Repair Surgery

Background: There are various protocols for pain management after anterior cruciate ligament (ACL) reconstruction surgery. Objective: This study aimed to compare two blocking protocols, including femoral nerve block (FNB) and infrapatellar nerve block (IPNB) in terms of pain severity, patient satisfaction, and muscle force preservation. Materials and Methods: This single-blind clinical trial study investigated the patients who underwent elective knee arthroscopic ACL surgery randomly either by ultrasound-guided FNB or IPNB. Subsequently, the patients were evaluated 1, 3, 6, 12, and 24 h following NB for pain severity, patient satisfaction level, and muscle force. Results: The pain score (both at rest and in flexion) was significantly lower in the first three h after the intervention in the FNB group. Moreover, the mean score of the patients’ satisfaction in the first hours was significantly higher in the FNB group after the procedure. Additionally, the IPNB group obtained a significantly faster mean time required for the first dose of opioid request. The mean dose of used opioids over 24 h was significantly lower in the FNB group. There was a significant difference between the groups in terms of the muscle strength score within 24 h; moreover, the FNB group obtained a significantly greater delay in muscle recovery. Conclusion: The FNB is associated with greater pain relief and satisfaction in patients who underwent arthroscopic ACL reconstruction surgery, compared to the IFNB technique. However, a further delay in the recovery of quadriceps muscle force is evident in the FNB group.

The Effects of Engineered Skeletal Muscle on Volumetric Muscle Loss in The Tibialis Anterior Of Rat After Three Months In Vivo.

Volumetric muscle loss (VML) is traumatic, degenerative, or surgical loss of skeletal muscle that exceeds the regenerative capacity of the remaining muscle, thus resulting in impaired muscle function. In humans, the loss of 30% or more mass of any one muscle will result in permanent structural and functional loss. Current VML repair treatments are limited by donor site morbidity and graft tissue availability, necessitating alternative muscle graft sources. To address this need, our lab has fabricated tissue-engineered skeletal muscle units (SMUs) for implantation into a 30 % VML model in the tibialis anterior (TA) muscle of rat. Previous results showed that after 28 days in vivo, muscle with a 30% VML repaired with our SMUs produced significantly more force than muscle with acute VML. But repair with our SMU did not fully restore muscle force production to that of native muscle. Thus, we hypothesized that more time for in vivo tissue regeneration would allow for greater force recovery. Therefore, the purpose of this study was to examine the long-term (3-month) effects of our SMUs on a 30% VML repair. We also assessed the effects of reinnervation by redirecting a branch of the peroneal nerve to the repair site. Thirty-nine, 2-month old female F344 rats were separated into a nonsurgical control group (n=5) and four surgical experimental groups (VML Only, n=5; VML+Nerve Redirect, n=6; VML+SMU, n=5; VML+SMU+ Nerve Redirect, n=8). Experimental rats were allowed a 3-month recovery period post-surgery before undergoing in situ force testing of the surgical (left) TA. The left TA of the control animals also underwent in situ force testing. Finally, the surgical (left) and contralateral (right) TAs of the experimental animals, as well as the left TA of the control animals, were explanted for histological analysis. Results for specific force showed that while all groups recovered specific forces similar to that of native muscle, the two SMU groups had significantly higher specific forces, on average, compared to the uninjured control group. Histological staining showed small muscle fibers in the repair site in animals that received an SMU. The average cross-sectional area of the native fibers just outside the area of repair (or the equivalent area in control animals) was not significantly different between groups, indicating that hypertrophy of remaining fibers did not contribute to the recovery of force following the VML. Our results suggest that following a 30% VML of the TA muscle, all surgical groups were able to recover TA mass, maximum tetanic and specific force production. Thus, creating a 30% VML in the TA in a rat model is not enough a sufficient VML to produce the sustained VML seen in humans following similar 30% loss of muscle volume.

Magnetic nanoadsorbents with amino-functionalized polymers for magnetic separation removal of copper ion

ABSTRACT The adsorption of copper ions on magnetic adsorbents with amino-functionalized polymers (DETA/SiO2/Fe3O4) has been investigated. In addition, the structure and characterization of magnetic nano-adsorbents were confirmed using FTIR, TGA, TEM, VSM, and BET. The results showed that DETA/SiO2/Fe3O4 exhibited a paramagnetic behaviour and could be easily recovered and quickly separated from a suspension solution. The optimum pH level for adsorption of copper ions was proposed to be in the range of pH level from 5 to 6, and the maximum adsorption capacity (qm ) and activated energy (Ea ) at 298 K was 13.459 mg g−1 and 22.421 kJ mol−1, respectively. The copper ions adsorption behaviour by DETA/SiO2/Fe3O4 was in good agreement with the Langmuir isotherm rather than Freundlich equation. A pseudo-second-order model could best describe the adsorption kinetics, and the optimal condition of copper ions desorption (99%) from DETA/SiO2/Fe3O4 was provided by 1.0 M HNO3. The novel magnetic nano-adsorbents could not only be regenerated by HNO3 solutions but also reused by the recovery of magnetic force without requiring further downstream treatment.

Effects of desflurane and sevoflurane anesthesia on postoperative recovery after long-term tumor surgery

Objective: To analyze the effects of desflurane and sevoflurane anesthesia on postoperative recovery after long lasting tumor surgery. Methods: One hundred and sixty patients undergoing endoscopic radical esophagectomy and gastrectomy (80 cases of each surgical type) from November 2019 to March 2020 at Henan Cancer Hospital, were randomized into 4 groups(n=40): group CS (esophageal cancer+sevoflurane anesthesia), group DS (esophageal cancer+desflurane anesthesia),group CW (stomach cancer+sevoflurane anesthesia) and group DW (gastric cancer+desflurane anesthesia). General anesthesia was induced by intravenous agents in all four groups, which were maintained by inhaled anesthetic during the operation. The mean arterial pressure (MAP), heart rate (HR), and surplus pulse O(2) (SpO(2)) immediately before induction (T(1)), the moment of operation begin (T(2)), operation end (T(3)) and extubation (T(4)) were recorded. Also, the duration required for inhalation anesthetic alveolar concentration reaching 0.5 minimum alveolar concentration (MAC) during induction, the alveolar anesthetic concentration at the beginning of the operation, the duration required for XMAC (patients specific alveolar concentration) declining to 0.5 MAC on recovery period, and the duration of alveolar concentration of 0.5 MAC declining to 0.2 MAC were determined. Additionally, the durations of spontaneous breathing recovery, eyes opening, extubation and recovery of consciousness were recorded. Finally, restlessness score (RS) during recovery period was used to evaluate postoperative agitation. Results: Compared with group CS and group CW, no significant differences in MAP, HR, SpO(2) in group DS and group DW at T(1) to T(4) were found (all P>0.05). The durations required for inhalation anesthetic alveolar concentration reaching 0.5 MAC were (5.6±1.3), (5.8±2.1), (3.5±1.5) and (3.8±1.0) min in group CS, group CW, group DS and group DW, where the durations in group DS and group DW were significantly shorter than those in group CS and group CW (F=32.538, P<0.05). The durations of alveolar concentration of 0.5 MAC declining to 0.2 MAC were (6.4±2.2), (7.0±1.5), (4.2±2.2) and (4.1±1.5) min in group CS, group CW, group DS and group DW, and the durations in group DS and group DW were significantly shortened as compared with group CS and group CW (F=42.113, P<0.05). Compared with group CS and group CW, group DS and group DW required significantly shorter time for spontaneous breathing recovery, eye opening,extubation, and directional force recovery after operation (all P<0.05). Conclusions: Both desflurane and sevoflurane anesthesia can achieve satisfactory anesthesia depth during long lasting tumor surgery. Desflurane can shorten the recovery time and early extubation, and improve the quality of recovery.

Acute Effects Of Photobiomodulation Therapy On Muscle Force Recovery In Persons With Multiple Sclerosis

Symptomatic fatigue, as well as muscle fatigue, are common in persons with multiple sclerosis (PwMS), and both can negatively affect quality of life (QOL). Photobiomodulation Therapy (PBMT), comprising light in a 600-1000 nm bandwidth, is an emerging therapeutic modality thought to enhance mitochondrial function. There is evidence that PBMT can improve muscle fatigue, inflammation, and psychological status and thus might be beneficial for PwMS. PURPOSE: To investigate PBMT on muscle force recovery after a fatiguing contraction in PwMS. A secondary aim was to determine if self-reported symptom outcomes influenced the response to PBMT. METHODS: Randomized double-blinded repeated-measures design. Ambulatory males and females (n=17, 14 females) with relapsing-remitting MS were evaluated pre- and post-PBMT in 4 visits over 4 weeks. The muscle function measurements consisted of 3 maximal voluntary contractions (MVCs) of Tibialis Anterior (TA) muscle followed by 2 min. of intermittent isometric contraction at 45% MVC. PBMT was then administered to the TA muscle belly at 1 of 4 energies: 40J, 80J, 120J or placebo (active device: 3 pulsed wavelengths at the same time including 640nm, 875nm, and 905nm, placebo device: single pulsed wavelength at 640 nm). After PBMT, recovery MVC’s were obtained. Baseline psychosocial measurements comprising depression (CES-D), fatigue (MFIS) and QOL (PROMIS) were obtained during visit 1. McNemar’s test was used to test for each light dose compared to placebo and Spearman’s correlations were compared with Fisher’s r to z transformation. RESULTS: All subjects were able to recover strength to within 12% of their initial strength during the 120J visit. However, 6/17 subjects did not recover to the same degree after the placebo. This difference in force recovery between high (120J) dose and placebo was significant with p=0.03. Muscle recovery correlations with depression and QOL differed between 120J vs. Placebo (0.35 vs. -0.44, p=0.03 and -0.09 vs. 0.67, p=0.03, respectively). CONCLUSIONS: PBMT at 120J may improve muscle force recovery in PwMS. Those reporting greater depression, or lower QOL may benefit most from PBMT. Supported by a pilot grant from the National MS Society