Stretch-Induced Healing of Injured Muscles Is Associated With Myogenesis and Decreased Fibrosis.

BACKGROUND: Alghouth therapeutic stretching exercise has been applied to accelerate the healing of injured skeletal muscles, mechanisms behind the mechanical stretch-induced muscle recovery remain unclear. PURPOSE: To examine stretch-associated antifibrotic and myogenic responses in injured muscles and to evaluate the feasibility of the ultrasonic Nakagami parametric index (NPI) in assessing muscle morphology during recovery. STUDY DESIGN: Controlled laboratory study. METHODS: Skeletal muscle fibrosis was induced in the right hind legs of 48 rats by making a posterior transverse incision in the gastrocnemius muscle; the left hind legs remained intact as a comparative normal reference. After surgery, the 48 rats were randomly divided into the stretch (S) and control (C) groups. The S group received stretching interventions on the injured hind leg from week 3 to week 7 after surgery, while the C group did not receive stretching throughout the study period. The muscle fibrosis percentage and the ultrasonic NPI were examined sequentially after surgery. Relative expressions of myogenesis-related proteins, including myoblast determination protein 1 (MyoD), myogenin, and embryonic myosin heavy chain (MHCemb), were also evaluated during the follow-up. RESULTS: Mean fibrosis percentages in the injured hind leg were approximately 25% at week 3 in both groups, but they were significantly decreased by approximately 20% from week 4 to the end of the follow-up in the S group only (all, P < .05). Upon injury, the NPI values of injured hind legs in both groups dramatically dropped. Within the S group, stretching increased the NPI values of injured hind legs, which approached those of control hind legs at weeks 6 and 7. The highest MyoD, myogenin, and MHCemb levels were observed at week 6 in both groups. The NPI values corresponded to the MyoD expression in the S group during the follow-up. CONCLUSION: Stretching induced a decrease in muscle fibrosis and an increase in myogenesis in injured muscles. The NPI values correspond to the myogenesis process. CLINICAL RELEVANCE: The NPI may be capable of continuously monitoring the injured skeletal muscle morphology during the healing process in clinical settings.

Increased serum brain-derived neurotrophic factor with high-intensity interval training in stroke patients: A randomized controlled trial.

BACKGROUND: Physiological adaptations of stroke patients after high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) remain unclear. OBJECTIVE: This study determined the HIIT and MICT effects on aerobic capacity, cerebral oxygenation, peak cardiac output (CO), and serum brain-derived neurotrophic factor (BDNF) in stroke patients. METHODS: We included 23 stroke patients with age about 55 years and stroke duration>24 months; participants completed 36 sessions of exercise training for 30min; 13 were randomly assigned to perform MICT at 60% of peak oxygen consumption (VO2peak) and 10 to perform HIIT at alternating 80% (3min) and 40% (3min) VO2peak. Before and after interventions, we evaluated VO2peak, peak CO, arteriovenous oxygen difference (AV O2diff), bilateral frontal cortex oxygenation (relative changes of oxyhemoglobin Δ[O2Hb], deoxyhemoglobin Δ[HHb], and total hemoglobin Δ[THb] levels), serum brain-derived neurotrophic factor (BDNF) level, and fluorescent cell staining for neuron morphology and percentage of cell-bearing neurites (% neurites). RESULTS: HIIT induced significant increases in VO2peak (P=0.008), CO (P=0.038), Δ[HHb] (P=0.046), Δ[THb] (P=0.046), and serum BDNF level (P=0.012). The improvement in VO2peak was significantly greater with HIIT than MICT (20.7% vs. 9.8%, P=0.031), as was AV O2diff (P=0.041), Δ[HHb] (P=0.027), and serum BDNF level (P<0.001). HIIT facilitated neuron dendritic protrusions (greater % neurites, P=0.012) with prominent redistribution of mitochondria. CONCLUSION: As compared with MICT, HIIT-improved aerobic capacity by increasing systemic tissue O2 extraction in stroke patients. Increased cerebral O2 utilization in the involved hemisphere was also identified after HIIT. These physiological adaptations may be associated with increased serum BDNF level. In vitro dendritic growth in neurons treated with serum from HIIT participants may imply significant effects on neuron activities as compared with MICT. CLINICALTRIALS. GOV IDENTIFIER: NCT04135391.

Longitudinal follow-up of muscle echotexture in infants with congenital muscular torticollis.

Unilateral fibrous contracture of the sternocleidomastoid (SCM) muscle is the major pathophysiology in infants with congenital muscular torticollis (CMT). Physical examination is not always sufficient to detect minimal muscle fibrosis in involved SCM muscles.A prospective study for SCM muscle fibrosis in CMT infants by quantifying echotexture and muscle thickness during the course of treatment is highlighted in the study.Convenience samples of 21 female and 29 male infants with CMT, who were 1 to 12 months old, underwent physiotherapy for at least 3 months and were followed for 4.7 ±â€Š0.4 months. All infants had at least 2 clinical assessments and ultrasonographic examinations for bilateral SCM muscles during follow-up. The K value, derived from the difference in echo intensities between the involved and uninvolved SCM muscles on longitudinal sonograms, was used to represent the severity of muscle fibrosis. Bilateral SCM muscle thickness and ratio of involved to uninvolved muscle thickness (Ratio I/U) were obtained simultaneously. Clinical outcome was also recorded.No subjects underwent surgical intervention during follow-up. The K value decreased from 6.85 ±â€Š0.58 to 1.30 ±â€Š0.36 at the end of follow-up (P < 0.001), which reflected the decrease of muscle fibrosis. The Ratio I/U decreased from 1.11 ±â€Š0.04 to 0.97 ±â€Š0.02 during treatment, which was possibly related to the increased uninvolved SCM muscle thickness.In conclusion, echotexture is an efficient indicator for reflecting a wide degree of muscle fibrosis in infants with CMT and is informative during the treatment course.

Negative pressure induces p120-catenin-dependent adherens junction disassembly in keratinocytes during wound healing.

A negative-pressure of 125mmHg (NP) has been widely used to treat chronic wounds in modern medicine. Keratinocytes under NP treatment have shown accelerated cell movement and decreased E-cadherin expression. However, the molecular mechanism of E-cadherin regulation under NP remains incompletely understood. Therefore, we investigated the E-cadherin regulation in keratinocytes (HaCaT cells) under NP. HaCaT cells were treated at ambient pressure (AP) and NP for 12h. Cell movement was measured by traditional and electric wound healing assays at the 2 different pressures. Mutants with overexpression of p120-catenin (p120(ctn)) were used to observe the effect of NP on p120(ctn) and E-cadherin expression during wound healing. Cell fractionation and immunoblotting data showed that NP increased Y228-phosphorylated p120(ctn) level and resulted in the translocation of p120(ctn) from the plasma membrane to cytoplasm. Immunofluorescence images revealed that NP decreased the co-localization of p120(ctn) and E-cadherin on the plasma membrane. Knockdown of p120(ctn) reduced E-cadherin expression and accelerated cell movement under AP. Overexpression of the Y228-phosphorylation-mimic p120(ctn) decreased E-cadherin membrane expression under both AP and NP. Phosphorylation-deficient mutants conferred restored adherens junctions (AJs) under NP. The Src inhibitor blocked the phosphorylation of p120(ctn) and impeded cell migration under NP. In conclusion, Src-dependent phosphorylation of p120(ctn) can respond rapidly to NP and contribute to E-cadherin downregulation. The NP-induced disassembly of the AJ further accelerates wound healing.

Quantifying cell behaviors in negative-pressure induced monolayer cell movement.

BACKGROUND: Negative-pressure of 125 mmHg (NP) has been shown to accelerate wound healing. Effects of NP on human keratinocyte behaviors during wound healing process were highlighted in this study. METHODS: An NP incubator incorporating the electric cell-substrate impedance sensing (ECIS) technique has been built to quantify monolayer keratinocytes movement in serum-free media at the ambient pressure (AP) and NP for 12 h. Monolayer cell motions were continuously recorded by ECIS in the frequency range of 22.5-64 kHz. Membrane capacitance (Cm), cell-substratum resistance (α), and cell-cell junction resistance (Rb) were evaluated in cells at the different pressures. RESULTS: A greater monolayer cell migration distance was found in cells at NP. Decreased cell-substratum adhesion reflected in the significantly low α (AP:NP = âˆ¼5 Ω(0.5):∼3 Ω(0.5)⋅cm), decreased integrin expression, and increased cell-substratum distance were seen in cells at NP. A significantly increased Cm (AP:NP = âˆ¼4:∼8 µF/cm(2)) in association with increased membrane ruffling and microtubule filaments were observed early in the monolayer cell movement at NP. A progressive drop in the Rb from 1.2 Ω·cm(2) to 0.8 Ω·cm(2) corresponding to the gradually decreased E-cadherin expressions were observed 6 h after wound closure after NP treatment. CONCLUSION: A quick membrane ruffling formation, an early cell-substratum separation, and an ensuing decrease in the cellular interaction occur in cells at NP. These specific monolayer cell behaviors at NP have been quantified and possibly accelerate wound healing.

Investigation of the Differential Contributions of Superficial and Deep Muscles on Cervical Spinal Loads with Changing Head Postures.

Cervical spinal loads are predominately influenced by activities of cervical muscles. However, the coordination between deep and superficial muscles and their influence on the spinal loads is not well understood. This study aims to document the changes of cervical spinal loads and the differential contributions of superficial and deep muscles with varying head postures. Electromyography (EMG) of cervical muscles from seventeen healthy adults were measured during maximal isometric exertions for lateral flexion (at 10°, 20° and terminal position) as well as flexion/extension (at 10°, 20°, 30°, and terminal position) neck postures. An EMG-assisted optimization approach was used to estimate the muscle forces and subsequent spinal loads. The results showed that compressive and anterior-posterior shear loads increased significantly with neck flexion. In particular, deep muscle forces increased significantly with increasing flexion. It was also determined that in all different static head postures, the deep muscle forces were greater than those of the superficial muscle forces, however, such pattern was reversed during peak efforts where greater superficial muscle forces were identified with increasing angle of inclination. In summary, the identification of significantly increased spinal loads associated with increased deep muscle activation during flexion postures, implies higher risks in predisposing the neck to occupationally related disorders. The results also explicitly supported that deep muscles play a greater role in maintaining stable head postures where superficial muscles are responsible for peak exertions and reinforcing the spinal stability at terminal head postures. This study provided quantitative data of normal cervical spinal loads and revealed motor control strategies in coordinating the superficial and deep muscles during physical tasks.

Altered Co-contraction of Cervical Muscles in Young Adults with Chronic Neck Pain during Voluntary Neck Motions.

[Purpose] Muscle co-contraction is important in stabilizing the spine. The aim of this study was to compare cervical muscle co-contraction in adults with and without chronic neck pain during voluntary movements. [Subjects and Methods] Surface electromyography of three paired cervical muscles was measured in fifteen young healthy subjects and fifteen patients with chronic neck pain. The subjects performed voluntary neck movements in the sagittal and coronal plane at slow speed. The co-contraction ratio was defined as the normalized integration of the antagonistic electromyography activities divided by that of the total muscle activities. [Results] The results showed that the co-contraction ratio of patients was greater during flexion movement, lesser during extension movement, slightly greater during right lateral bending, and slightly lesser during left lateral bending compared with in the controls. [Conclusion] The results suggested that neck pain patients exhibit greater antagonistic muscle activity during flexion and dominate-side bending movements to augment spinal stability, while neuromuscular control provides relatively less protection in the opposite movements. This study helps to specify the changes of the stiffness of the cervical spine in neck pain patients and provides a useful tool and references for clinical assessment of neck disorders.

Negative pressure accelerated monolayer keratinocyte healing involves Cdc42 mediated cell podia formation.

BACKGROUND: Negative-pressure wound therapy (NPWT) is developed to facilitate wound healing at controlled subatmospheric pressures in modern medicine. Molecular mechanism for this therapy is still undefined. OBJECTIVE: This study highlights the localization and time-course of the cell division control protein 42 (Cdc42) in the cell membrane at ambient pressure (AP) and negative pressures of 75mmHg (NP75), 125mmHg (NP125) and 175mmHg (NP175). METHODS: The prepared cells were cultured in a negative pressure incubator with the same O2 and CO2 tensions at the four different pressures. The effective time, complete wound closure time, cell volume, cell viability, and the fluorescence of proliferating cell nuclear antigens (PCNA) and actins were evaluated in cells at different pressures. Wound-healing process and Cdc42 fluorescence were examined in cells with the knockdown of Cdc42. Cdc42 pathway proteins in cell membranes were analyzed after incubation at different pressures for 6 and 12h. RESULTS: The cells at NP125 had less wound closure time and obvious cell podia. Similar PCNA fluorescent intensity was observed in cells at different pressures. The Cdc42, neural Wiskott-Aldrich syndrome protein, and actin expression increased significantly (p<0.05) in plasma membranes of cells at NP125 for 12h. The knockdown of active Cdc42 resulted in the absence of Cdc42 expression at the cell leading edge. CONCLUSIONS: The activation and localization of Cdc42 pathway proteins in the cell membrane are involved in the cell podia formation in keratinocytes at NP125. NPWT may facilitate cell migration to accelerate wound healing.

Determination of the augmentation effects of hyaluronic acid on different heel structures in amputated lower limbs of diabetic patients using ultrasound elastography.

This study measured tissue properties of different anatomies of heels in amputated lower limbs of diabetic patients before and after hyaluronic acid (HA) or normal saline (NS) injections. Seven amputated lower limbs from six diabetic patients constituted the experimental group and one amputated lower limb from a diabetic patient served as the control. The limbs were placed in a fixation platform. A 5-12 MHz linear-array ultrasound transducer controlled by a stepping motor was used to load and unload tested heels. The loading-unloading velocity was 6 mm/s and the maximum loading stress was 178 kPa. Loading-unloading tests were performed before and after 1 mL HA injections into heels in the experimental group. The control limb underwent the same test before and after 1 mL NS injection. The unloaded thickness and Young's modulus of the macrochambers, microchambers and heel pads were determined before and after the interventions. The unloaded thickness of the macrochambers and the heel pad increased significantly (p = 0.012) after HA injection. The Young's modulus of the macrochambers decreased nonsignificantly after HA injections. Similar thickness and tissue stiffness changes were observed in the control limb. The baseline heel-pad energy dissipation ratio (EDR(hp)) was 81.3 ± 1.3% and decreased significantly (p = 0.012) to 73.1 ± 1.7% after HA injections. The EDR(hp) in the control increased after NS injection. Histologic examinations revealed localized HA accumulation in the macrochambers with an extension into the adjacent fibrous septa. Injection of HA can increase tissue thickness and enhance heel-pad tissue resilience.

Quantification of skeletal muscle fibrosis at different healing stages using sonography: a morphologic and histologic study in an animal model.

OBJECTIVES: This study attempted to quantify the degree of muscle fibrosis on sonograms of injured gastrocnemius muscles at different healing stages in a rat model. Correlations between the quantifications and histologic assessments of the injured muscles were also determined. METHODS: Sonograms and histologic findings of gastrocnemius muscle fibrosis were obtained during the second, third, and fourth weeks after surgically induced lesions in the right gastrocnemius muscles of 15 Wistar rats. The echo intensity, reflecting the degree of brightness on a sonogram, was divided into 256 gray levels instead of decibels. The mean echo intensity of each pixel in the region of interest was calculated as a summation of the echo intensities in all pixels divided by the pixel numbers in the region. To control individual variations among the rats, we calculated a K value, defined as the difference in the mean echo intensity between normal and affected muscles. RESULTS: Significant correlations (r > 0.7; P < .05) between mean echo intensity and K values and the fibrous tissue percentage were identified. The mean echo intensity in the injured gastrocnemius muscles was significantly (P = .029) greater than that in the normal muscles 3 weeks after injury. In histologic assessments, muscle fibrosis was most prominent 3 weeks after injury. However, the differences in fibrosis at different healing stages were not significant. CONCLUSIONS: Mean echo intensity and K values can reflect the extent of fibrosis in affected muscles and may be valuable for quantifying muscle fibrosis in clinical practice.

Effects of negative pressures on epithelial tight junctions and migration in wound healing.

Negative-pressure wound therapy has recently gained popularity in chronic wound care. This study attempted to explore effects of different negative pressures on epithelial migration in the wound-healing process. The electric cell-substrate impedance sensing (ECIS) technique was used to create a 5 x 10(-4) cm(2) wound in the Madin-Darby canine kidney (MDCK) and human keratinocyte (HaCaT) cells. The wounded cells were cultured in a negative pressure incubator at ambient pressure (AP) and negative pressures of 75 mmHg (NP(75)), 125 mmHg (NP(125)), and 175 mmHg (NP(175)). The effective time (ET), complete wound healing time (T(max)), healing rate (R(heal)), cell diameter, and wound area over time at different pressures were evaluated. Traditional wound-healing assays were prepared for fluorescent staining of cells viability, cell junction proteins, including ZO-1 and E-cadherin, and actins. Amount of cell junction proteins at AP and NP(125) was also quantified. In MDCK cells, the ET (1.25 +/- 0.27 h), T(max) (1.76 +/- 0.32 h), and R(heal) (2.94 +/- 0.62 x 10(-4) cm(2)/h) at NP(125) were significantly (P < 0.01) different from those at three other pressure conditions. In HaCaT cells, the T(max) (7.34 +/- 0.29 h) and R(heal) (6.82 +/- 0.26 x 10(-5) cm(2)/h) at NP(125) were significantly (P < 0.01) different from those at NP(75). Prominent cell migration features were identified in cells at the specific negative pressure. Cell migration activities at different pressures can be documented with the real-time wound-healing measurement system. Negative pressure of 125 mmHg can help disassemble the cell junction to enhance epithelial migration and subsequently result in quick wound closure.

Elevation of CSF albumin in old sheep: relations to CSF turnover and albumin extraction at blood-CSF barrier.

Albumin is the most abundant protein in both CSF and plasma, and albumin quotient is often used to assess the functions of brain barriers especially that of the blood-CSF barrier [i.e. the choroid plexus (CP) which also secretes CSF]. In this study, we took albumin as a model molecule to investigate ageing-related alterations in the CSF-CP system in sheep. We found significant ageing-related increases in the weight of lateral CP [122.4 +/- 14.0 mg in the young, 198.6 +/- 35.4 mg in the middle aged, 286.1 +/- 25.1 mg in the old (p < 0.05)], in the CSF albumin as well as the albumin quotient. Albumin protein spots in old CSF displayed wider on 2D western immunoblotting images, and had higher densities on images of 2D large gels stained with Pro-Q Emerald 488 compared to the young samples, suggesting ageing-related post-translational modification in the albumin. CSF secretion was reduced with age: 0.148 +/- 0.013 mL/min/g in the young, 0.092 +/- 0.02 mL/min/g in the middle aged, 0.070 +/- 0.013 mL/min/g in the old (p < 0.05). The (125)I-BSA extraction was not different among the sheep groups, nor was altered by temperature reduction, monensin, nocodazole, anti-transforming growth factor beta receptor II antibody, as well as unlabelled albumins. In conclusion, elevation of albumin in old CSF is associated with reduced CSF secretion by the CP, which size increases with age. (125)I-BSA extract, reflecting the extracellular space rather than the active albumin uptake in the CP, is not different between ages. These early changes in health ageing may result in the accumulation and modifications of CSF proteins leading to neurotoxicity.

Effects of aging on the plantar soft tissue properties under the metatarsal heads at different impact velocities.

The plantar soft tissue properties under the metatarsal heads at different impact velocities in different age groups were measured. Each metatarsus of the left foot in healthy young adults (n = 9, 19 to 35 years old) and in healthy older persons (n = 10, 42 to 72 years old) was examined in vivo using a self-constructed loading-unloading device at low, medium and high impact status; the impact velocities of the device were about 2.5, 5 and 10 cm/s, respectively. The device comprised a 5- to 12-MHz linear-array ultrasound transducer, a miniature load cell and a fixation frame. From low to high impact status, the elastic modulus (E) in young adults significantly increased from about 300 kPa to about 500 kPa. However, the E in the older group did not show this trend. From low to high impact status, the energy dissipation ratio (EDR) of the metatarsus significantly increased from about 30% to about 60% in the young group and significantly increased from about 40% to about 70% in the older group. Most of the metatarsus in the older subjects had significantly greater E and EDR than those in the younger persons.

Ultrasonographic examination of the normal and injured posterior cruciate ligament.

PURPOSE: The purpose of the study was to determine the echogenicity and thickness of both the normal and injured posterior cruciate ligament (PCL). METHODS: Eight patients with anterior cruciate ligament injury received ultrasonographic evaluation during arthroscopic examination. With the aid of the comet-tail artifact produced by the metal hook during arthroscopic examination, the normal PCL was located on sonograms. Thereafter, 11 patients with PCL injury were examined. In all subjects, the PCL thickness was measured at 2.0 cm proximal from posterior end of the distal PCL inserting onto the tibia. RESULTS: The normal PCL was located just posterior to the posterior tibial intercondylar area. It was hypo-echoic and was thickened proximally and tapered distally. The mean thickness of the injured PCL was 0.71 +/- 0.12 cm, which was significantly (p < 0.05) greater than that of the normal ligament (0.52 +/- 0.08 cm). Different appearances could be observed, including ligamental rupture and avulsion fracture of the tibial insertion of the PCL. CONCLUSIONS: The normal PCL appears on longitudinal sonograms as a hypoechoic fan-shape structure. Sonographic examination can identify different types of PCL lesions.