Muscle Defects Research Articles

Loss of STING in parkin mutant flies suppresses muscle defects and mitochondria damage.

The early pathogenesis and underlying molecular causes of motor neuron degeneration in Parkinson's Disease (PD) remains unresolved. In the model organism Drosophila melanogaster, loss of the early-onset PD gene parkin (the ortholog of human PRKN) results in impaired climbing ability, damage to the indirect flight muscles, and mitochondrial fragmentation with swelling. These stressed mitochondria have been proposed to activate innate immune pathways through release of damage associated molecular patterns (DAMPs). Parkin-mediated mitophagy is hypothesized to suppress mitochondrial damage and subsequent activation of the cGAS/STING innate immunity pathway, but the relevance of this interaction in the fly remains unresolved. Using a combination of genetics, immunoassays, and RNA sequencing, we investigated a potential role for STING in the onset of parkin-null phenotypes. Our findings demonstrate that loss of Drosophila STING in flies rescues the thorax muscle defects and the climbing ability of parkin-/- mutants. Loss of STING also suppresses the disrupted mitochondrial morphology in parkin-/- flight muscles, suggesting unexpected feedback of STING on mitochondria integrity or activation of a compensatory mitochondrial pathway. In the animals lacking both parkin and sting, PINK1 is activated and cell death pathways are suppressed. These findings support a unique, non-canonical role for Drosophila STING in the cellular and organismal response to mitochondria stress.

Dual Application of Mesh through Hybrid Technique in Large Incisional Hernia: A Case Report

Although single mesh insertion is recommended for simple incisional hernia, there is no established treatment of choice for severe incisional hernia accompanied with large muscular defects. Single mesh insertion cannot provide sufficient mechanical force, and muscle flaps could lead to donor site morbidity while also requiring longer operation times. In this case, dual application of mesh through a hybrid technique could be a good option. A 46-year-old woman with rectus abdominis muscle defect due to previous surgery visited our clinic with abdominal bulging. Abdomen-pelvis computed tomography demonstrated a 6.5×11.5 cm rectus abdominis defect along with small bowel herniation. We decided to reinforce the existing hybrid intraperitoneal onlay mesh technique through additional insertion of suprafascial mesh to prevent recurrence and minimize complications. The patient’s abdominal contour was well preserved postoperatively for 1 year. We believe dual-layer mesh insertion through a hybrid approach could be a better alternative for severe incisional hernia with large muscle defects because of its treatment efficacy, short operation time, simple technical requirements, and absence of donor or flap complications.

The effect of Trolox on the rabbit anal sphincterotomy repair

IntroductionFecal incontinence (FI) is caused by external anal sphincter injury. Vitamin E is a potential strategy for anal sphincter muscle repair via its antioxidant, anti-inflammatory, anti-fibrotic, and protective properties against myocyte loss. Thus, we aimed to evaluate the water-soluble form of vitamin E efficacy in repairing anal sphincter muscle defects in rabbits.MethodsTwenty-one male rabbits were equally assigned to the intact (without any intervention), control (sphincterotomy), and Trolox (sphincterotomy + Trolox administration) groups. Ninety days after sphincterotomy, the resting and squeeze pressures were evaluated by manometry, and the number of motor units in the sphincterotomy site was calculated by electromyography. Also, the amount of muscle and collagen in the injury site was investigated by Mallory’s trichrome staining.ResultsNinety days after the intervention, the resting and squeeze pressures in the intact and Trolox groups were significantly higher than in the control group (P = 0.001). Moreover, the total collagen percentage of the sphincterotomy site was significantly lower in the Trolox group than in the control group (P = 0.002), and the total muscle percentage was significantly higher in the Trolox group compared to the control group (P = 0.001). Also, the motor unit number was higher in the Trolox group than in the control group (P = 0.001).ConclusionTrolox administration in the rabbit sphincterotomy model can decrease the amount of collagen and increase muscle, leading to improved anal sphincter electromyography and manometry results. Therefore, Trolox is a potential treatment strategy for FI.

Monoradiculopathy-induced abdominal pseudohernia caused by T11-12 soft disc herniation: a case report and literature review

BackgroundAn abdominal pseudohernia is a rare clinical entity that consists of an abnormal bulging of the abdominal wall that can resemble a true hernia but does not have an associated underlying fascial or muscle defect. Abdominal pseudohernia is believed to result from denervation of the abdominal muscles in cases of herpes zoster infection, diabetes mellitus, lower thoracic or upper lumbar disc herniation, surgical injuries, and rib fracture. To date, nine cases of abdominal pseudohernia caused by disc herniation at the lower thoracic or upper lumbar levels have been reported.Case presentationA 35-year-old man with no underlying disease or traumatic event presented with chief complaints of left flank pain and a protruding left lower abdominal mass that had formed one day earlier. There was no true abdominal hernia on abdominal computed tomography (CT), although CT and magnetic resonance imaging (MRI) showed a herniated soft (non-calcified) disc into the left neural foramen at the T11-12 level. A nonsteroidal anti-inflammatory drug was prescribed for the flank pain, and the patient was followed on a regular basis for six months. Follow-up MRI taken at the last visit showed complete resorption of the herniated disc. Abdominal pseudohernia and flank pain were also completely resolved.ConclusionWe report a rare case of monoradiculopathy-induced abdominal pseudohernia caused by foraminal soft disc herniation at the T11-12 level. In patients who have an abdominal pseudohernia without herpes zoster infection, diabetes mellitus, or traumatic events, lower thoracic disc herniations should be included in differential diagnosis.

Restoration of brain dystrophin using tricyclo-DNA ASOs restores neurobehavioral deficits in DMD mice

Restoration of brain dystrophin using tricyclo-DNA ASOs restores neurobehavioral deficits in DMD mice

Functional hydrogels for the repair and regeneration of tissue defects.

Tissue defects can be accompanied by functional impairments that affect the health and quality of life of patients. Hydrogels are three-dimensional (3D) hydrophilic polymer networks that can be used as bionic functional tissues to fill or repair damaged tissue as a promising therapeutic strategy in the field of tissue engineering and regenerative medicine. This paper summarises and discusses four outstanding advantages of hydrogels and their applications and advances in the repair and regeneration of tissue defects. First, hydrogels have physicochemical properties similar to the extracellular matrix of natural tissues, providing a good microenvironment for cell proliferation, migration and differentiation. Second, hydrogels have excellent shape adaptation and tissue adhesion properties, allowing them to be applied to a wide range of irregularly shaped tissue defects and to adhere well to the defect for sustained and efficient repair function. Third, the hydrogel is an intelligent delivery system capable of releasing therapeutic agents on demand. Hydrogels are capable of delivering therapeutic reagents and releasing therapeutic substances with temporal and spatial precision depending on the site and state of the defect. Fourth, hydrogels are self-healing and can maintain their integrity when damaged. We then describe the application and research progress of functional hydrogels in the repair and regeneration of defects in bone, cartilage, skin, muscle and nerve tissues. Finally, we discuss the challenges faced by hydrogels in the field of tissue regeneration and provide an outlook on their future trends.

Phosphorylation of the Myogenic Factor Myocyte Enhancer Factor-2 Impacts Myogenesis InVivo.

Activity of the myogenic regulatory protein myocyte enhancer factor-2 (MEF2) is modulated by post-translational modification. We investigated the invivo phosphorylation of Drosophila MEF2, and identified serine 98 (S98) as a phosphorylated residue. Phospho-mimetic (S98E) and phospho-null (S98A) isoforms of MEF2 did not differ from wild-type in their activity invitro, so we used CRISPR/Cas9 to generate an S98A allele of the endogenous gene. In mutant larvae we observed phenotypes characteristic of reduced MEF2 function, including reduced body wall muscle size and reduced expression of myofibrillar protein genes; conversely,S98A homozygotes showed enhanced MEF2 function through muscle differentiation within the adult myoblasts associated with the wing imaginal disc. In adults, S98A homozygotes were viable with normal mobility, yet showed patterning defects in muscles that were enhanced when the S98A allele was combined with a Mef2 null allele. Overall our data indicate that blocking MEF2 S98 phosphorylation in myoblasts enhances its myogenic capability, whereas blocking S98 phosphorylation in differentiating muscles attenuates MEF2 function. Our studies are among the first to assess the functional significance of MEF2 phosphorylation sites in the intact animal, and suggest that the same modification can have profoundly different effects upon MEF2 function depending upon the developmental context.

Protective Effects of Hemp (Cannabis sativa) Root Extracts against Insulin-Deficient Diabetes Mellitus In Mice.

The pharmacological potential of industrial hemp (Cannabis sativa) has been widely studied. However, the majority of studies have focused on cannabidiol, isolated from the inflorescence and leaf of the plant. In the present study, we evaluated the anti-diabetic potential of hemp root water (HWE) and ethanol extracts (HEE) in streptozotocin (STZ)-induced insulin-deficient diabetic mice. The administration of HWE and HEE ameliorated hyperglycemia and improved glucose homeostasis and islet function in STZ-treated mice (p < 0.05). HWE and HEE suppressed β-cell apoptosis and cytokine-induced inflammatory signaling in the pancreas (p < 0.05). Moreover, HWE and HEE normalized insulin-signaling defects in skeletal muscles and apoptotic response in the liver and kidney induced by STZ (p < 0.05). Gas chromatography-mass spectrometry analysis of HWE and HEE showed possible active compounds which might be responsible for the observed anti-diabetic potential. These findings indicate the possible mechanisms by which hemp root extracts protect mice against insulin-deficient diabetes, and support the need for further studies geared towards the application of hemp root as a novel bioactive material.

Low-dose spironolactone attenuates metabolic defects in the skeletal muscle of letrozole-induced hyperandrogenic female rats

Low-dose spironolactone attenuates metabolic defects in the skeletal muscle of letrozole-induced hyperandrogenic female rats

Abstract 3666: A human skeletal muscle stem/myotube model reveals multiple signaling targets of cancer secretome in skeletal muscle

Abstract Skeletal muscle dysfunction due to the effects of cancer secretome is observed in multiple cancer types and extreme dysfunction is manifested as cachexia. Major preclinical studies on cancer-associated muscle defects utilized mouse models or mouse C2C12 mouse myoblast cell line for in vitro studies. Because of species specificity of certain cytokines/chemokines in the secretome, a human model system is required to fully comprehend the effects of cancer secretome on skeletal muscle. Here, we report a simple method to establish skeletal muscle stem cell line (hMuSC), which can be differentiated into myotubes. Using single nuclei ATAC-seq (snATAC-seq) and RNA-seq (snRNA-seq), we document chromatin accessibility and transcriptomic changes associated with hMuSCs to myotube transition. Cancer cell line derived factors accelerated stem to myotube differentiation with accompanying changes including an increase in PAX7+/MyoD+ myogenic progenitor cells. Among the pathways activated by cancer-derived factors include inflammatory pathway involving CXCL8 (also called IL-8), glucocorticoid receptor (GR) pathway, and wound healing pathway. Furthermore, cancer-derived factors significantly altered splicing machinery in hMuSCs. Additionally, AKT and p53 pathways that function in metabolic/survival pathways of the skeletal muscle were adversely affected when hMuSCs were exposed to cancer cell-derived factors. Cancer-derived factors increased the expression levels of previously known cachexia-associated genes such as MT-2, ZIP14, and PDK4. Thus, the model system not only recapitulates results of previous mouse studies but also provides much needed human model system that can easily be adapted for large scale studies to explore the epigenomic changes during hMuSC differentiation and to screen for drugs that restore skeletal muscle function in various diseases. Citation Format: Ruizhong Wang, Brijesh Kumar, Poornima Bhat-Nakshatri, Aditi Sanjay Khatpe, Michael P. Murphy, Kristen E. Wanczyk, Emma H. Doud, Amber L. Mosley, Yunlong Liu, Duojiao Chen, Ed Simpson, Hongyu Gao, Harikrishna Nakshatri. A human skeletal muscle stem/myotube model reveals multiple signaling targets of cancer secretome in skeletal muscle. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3666.

Feasibility of imaging under structured illumination for evaluation of white striping in broiler breast fillets

Muscle myopathies or defects, such as white striping (WS), downgrade the quality of broiler meat, leading to the loss of millions of dollars annually for the U.S. poultry industry. Visual inspection is currently practiced for assessing myopathies in broiler meat, which is however prone to human evaluation error, labor-intensive, and costly. Imaging under uniform or diffuse illumination has been investigated for assessing broiler meat quality, but their performance is not always satisfactory, especially for detecting subtle defects with few visual symptoms. This study presents the first proof-of-concept evaluation of the utility of an innovative technique for improved imaging of structures of biological materials, i.e., structured-illumination reflectance imaging (SIRI), for detecting WS conditions in broiler breast meat. Broiler breast fillets with varying degrees of WS severity were imaged by an in-house assembled SIRI system under sinusoidal illumination at different spatial frequencies (0.05–0.40 cycles/mm). The acquired pattern images were demodulated into direct components (DC) and amplitude components (AC) at each spatial frequency. Texture features were extracted from DC and AC images for building classification models using regularized linear discriminant analysis, which were to classify meat samples into 2, 3, and 4 classes, respectively, according to WS conditions. AC images were found by visual inspection more effective than DC in resolving WS characteristics, depending on the spatial frequency of illumination patterns. Compared to DC, AC yielded the maximum accuracy improvements of 8.33%, 7.93%, and 12.3% in 2-, 3- and 4-class classifications, respectively. Models using ranked features yielded similar improvements of up to 9.53% by AC over DC. The SIRI technique is promising for enhanced detection of WS and potentially other defects of broiler breast meat. • Structured-illumination reflectance imaging (SIRI) was used for poultry quality detection. • Amplitude component (AC) images enabled resolving white striping (WS) of broiler breast meat. • Broiler breast fillets were classified by models into 2, 3 and 4 classes according to WS conditions. • SIRI offered substantial improvements of up to 12% in classifying WS-affected poultry samples.

The small compound Icerguastat reduces muscle defects in oculopharyngeal muscular dystrophy through the PERK pathway of the unfolded protein response

Oculopharyngeal muscular dystrophy (OPMD) is an autosomal dominant disease characterized by the progressive degeneration of specific muscles. OPMD is due to a mutation in the gene encoding poly(A) binding protein nuclear 1 (PABPN1) leading to a stretch of 11 to 18 alanines at N-terminus of the protein, instead of 10 alanines in the normal protein. This alanine tract extension induces the misfolding and aggregation of PABPN1 in muscle nuclei. Here, using Drosophila OPMD models, we show that the unfolded protein response (UPR) is activated in OPMD upon endoplasmic reticulum stress. Mutations in components of the PERK branch of the UPR reduce muscle degeneration and PABPN1 aggregation characteristic of the disease. We show that oral treatment of OPMD flies with Icerguastat (previously IFB-088), a Guanabenz acetate derivative that shows lower side effects, also decreases muscle degeneration and PABPN1 aggregation. Furthermore, the positive effect of Icerguastat depends on GADD34, a key component of the phosphatase complex in the PERK branch of the UPR. This study reveals a major contribution of the ER stress in OPMD pathogenesis and provides a proof-of-concept for Icerguastat interest in future pharmacological treatments of OPMD.

3D bioprinting using a new photo-crosslinking method for muscle tissue restoration

Three-dimensional (3D) bioprinting is a highly effective technique for fabricating cell-loaded constructs in tissue engineering. However, the versatility of fabricating precise and complex cell-loaded hydrogels is limited owing to the poor crosslinking ability of cell-containing hydrogels. Herein, we propose an optic-fiber-assisted bioprinting (OAB) process to efficiently crosslink methacrylated hydrogels. By selecting appropriate processing conditions for the photo-crosslinking technique, we fabricated biofunctional cell-laden structures including methacrylated gelatin (Gelma), collagen, and decellularized extracellular matrix. To apply the method to skeletal muscle regeneration, cell-laden Gelma constructs were processed with a functional nozzle having a topographical cue and an OAB process that could induce a uniaxial alignment of C2C12 and human adipose stem cells (hASCs). Significantly higher degrees of cell alignment and myogenic activities in the cell-laden Gelma structure were observed compared with those in the cell construct that was printed using a conventional crosslinking method. Moreover, an in vivo regenerative potential was observed in volumetric muscle defects in a mouse model. The hASC-laden construct significantly induced greater muscle regeneration than the cell construct without topographical cues. Based on the results, the newly designed bioprinting process can prove to be highly effective in fabricating biofunctional cell-laden constructs for various tissue engineering applications.

A human skeletal muscle stem/myotube model reveals multiple signaling targets of cancer secretome in skeletal muscle

Skeletal muscle dysfunction or reprogramming due to the effects of the cancer secretome is observed in multiple malignancies. Although mouse models are routinely used to study skeletal muscle defects in cancer, because of species specificity of certain cytokines/chemokines in the secretome, a human model system is required. Here, we establish simplified multiple skeletal muscle stem cell lines (hMuSCs), which can be differentiated into myotubes. Using single nuclei ATAC-seq (snATAC-seq) and RNA-seq (snRNA-seq), we document chromatin accessibility and transcriptomic changes associated with the transition of hMuSCs to myotubes. Cancer secretome accelerated stem to myotube differentiation, altered the alternative splicing machinery and increased inflammatory, glucocorticoid receptor, and wound healing pathways in hMuSCs. Additionally, cancer secretome reduced metabolic and survival pathway associated miR-486, AKT, and p53 signaling in hMuSCs. hMuSCs underwent myotube differentiation when engrafted into NSG mice and thus providing a humanized invivo skeletal muscle model system to study cancer cachexia.

Role of muscle FOXO gene in exercise against the skeletal muscle and cardiac age-related defects and mortality caused by high-salt intake in Drosophila

FOXO has long been associated with aging, exercise, and tissue homeostasis, but it remains unclear what the role is of the muscle FOXO gene in E against high-salt intake(HSI)-induced age-related defects of the skeletal muscle, heart, and mortality. In this research, overexpression and RNAi of the FOXO gene in the skeletal and heart muscle of Drosophila were constructed by building Mhc-GAL4/FOXO-UAS-overexpression and Mhc-GAL4/FOXO-UAS-RNAi system. The skeletal muscle and heart function, the balance of oxidation and antioxidant, and mitochondrial homeostasis were measured. The results showed that exercise reversed the age-related decline in climbing ability and downregulation of muscle FOXO expression induced by HSI. Muscle-specific FOXO-RNAi (FOXO-RNAi) and -overexpression (FOXO-OE) promoted or slowed the age-related decline in climbing ability, heart function, and skeletal muscle and heart structure damage, which was accompanied by the inhibition or activation of FOXO/PGC-1α/SDH and FOXO/SOD pathway activity, and oxidative stress (ROS) increased or decreased in both skeletal muscle and heart. The protective effect of exercise on the skeletal muscle and heart was blocked by FOXO-RNAi in aged HSI flies. FOXO-OE prolonged its lifespan, but it did not resist the HSI-induced lifespan shortening. Exercise did not improve HSI-induced lifespan shortening in FOXO-RNAi flies. Therefore, current results confirmed that the muscle FOXO gene played a vital role in exercise against age-related defects of the skeletal muscle and heart induced by HSI because it determined the activity of muscle FOXO/SOD and FOXO/PGC-1α/SDH pathways. The muscle FOXO gene also played an important role in exercise against HSI-induced mortality in aging flies.

A comparison of MRI-based pelvic floor support measures between young and old women with prolapse.

We sought to 1) test the hypothesis that young women (≤45years) with pelvic organ prolapse have a higher prevalence of major levator ani muscle (LAM) defects than old women (≥70years) with prolapse and 2) compare level II/III measurements between young and old women with prolapse and age-matched controls to evaluate age-related mechanistic differences in the disease process. A secondary analysis examined four groups of parous women: young prolapse (YPOP, n = 17); old prolapse (OPOP, n = 17); young controls (YC, n = 15); old controls, (OC, n = 13). Prolapse was defined as any compartment at or beyond the hymen with vaginal bulge symptoms. Genital hiatus (GH) was measured on clinical exam. Major LAM defects and level II/III measurements (UGH: urogenital hiatus, LA: levator area, and apex location) were assessed on MRI at rest and strain, and the difference (Δ) between measurements calculated. Principal component analysis was used to evaluate levator plate (LP) shape. Major LAM defects occurred in 42% of YPOP and 47% of OPOP (p > .99). GHrest was 1.5cm larger in OPOP versus YPOP (p < .001) and 2cm larger in OPOP versus OC (p < .001). Regardless of prolapse status, LArest and UGHrest on MRI increased with age. YPOP had larger ΔLA (p = .04), ΔUGH (p = .03), and Δapex than OPOP (p = .01). Resting LP shape was more dorsally oriented in OPOP versus YPOP (p = .02) and OC versus YC (p = .004). Prolapse in young women cannot be solely explained by a higher LAM defect prevalence. GH size and other measures of level II/III pelvic support worsen with age regardless of prolapse status.

A transcriptomic signature of X chromosome overdosage in Saudi Klinefelter syndrome induced pluripotent stem cells.

The transcriptional landscape of Klinefelter syndromeduring early embryogenesis remains elusive. This study aimed to evaluate the impact of X chromosome overdosage in 47,XXY males induced pluripotent stem cells (iPSCs) obtained from patients with different genomic backgrounds and ethnicities. We derived and characterized 15 iPSC lines from four Saudi 47,XXY KS patients and one Saudi 46,XY male. We performed a comparative transcriptional analysis using the Saudi KS-iPSCs and a cohort of European and North American KS-iPSCs. We identified a panel of X-linked and autosomal genes commonly dysregulated in Saudi and European/North American KS-iPSCs vs 46,XY controls. Our findings demonstrate that seven PAR1 and nine non-PAR escape genes are consistently dysregulated and mostly display comparable transcriptional levels in both groups. Finally, we focused on genes commonly dysregulated in both iPSC cohorts and identified several gene-ontology categories highly relevant to KS physiopathology, including aberrant cardiac muscle contractility, skeletal muscle defects, abnormal synaptic transmission, and behavioral alterations. Our results indicate that a transcriptomic signature of X chromosome overdosage in KS is potentially attributable to a subset of X-linked genes sensitive to sex chromosome dosage and escaping X inactivation, regardless of the geographical area of origin, ethnicity, and genetic makeup.

Aerobic exercise and scaffolds with hierarchical porosity synergistically promote functional recovery post volumetric muscle loss

Volumetric muscle loss (VML), which refers to a composite skeletal muscle defect, most commonly heals by scarring and minimal muscle regeneration but substantial fibrosis. Current surgical interventions and physical therapy techniques are limited in restoring muscle function following VML. Novel tissue engineering strategies may offer an option to promote functional muscle recovery. The present study evaluates a colloidal scaffold with hierarchical porosity and controlled mechanical properties for the treatment of VML. In addition, as VML results in an acute decrease in insulin-like growth factor 1 (IGF-1), a myogenic factor, the scaffold was designed to slowly release IGF-1 following implantation. The foam-like scaffold is directly crosslinked onto remnant muscle without the need for suturing. In situ 3D printing of IGF-1-releasing porous muscle scaffold onto VML injuries resulted in robust tissue ingrowth, improved muscle repair, and increased muscle strength in a murine VML model. Histological analysis confirmed regeneration of new muscle in the engineered scaffolds. In addition, the scaffolds significantly reduced fibrosis and increased the expression of neuromuscular junctions in the newly regenerated tissue. Exercise training, when combined with the engineered scaffolds, augmented the treatment outcome in a synergistic fashion. These data suggest highly porous scaffolds and exercise therapy, in combination, may be a treatment option following VML.

Loss of calpain3b in Zebrafish, a Model of Limb-Girdle Muscular Dystrophy, Increases Susceptibility to Muscle Defects Due to Elevated Muscle Activity.

Limb-Girdle Muscular Dystrophy Type R1 (LGMDR1; formerly LGMD2A), characterized by progressive hip and shoulder muscle weakness, is caused by mutations in CAPN3. In zebrafish, capn3b mediates Def-dependent degradation of p53 in the liver and intestines. We show that capn3b is expressed in the muscle. To model LGMDR1 in zebrafish, we generated three deletion mutants in capn3b and a positive-control dmd mutant (Duchenne muscular dystrophy). Two partial deletion mutants showed transcript-level reduction, whereas the RNA-less mutant lacked capn3b mRNA. All capn3b homozygous mutants were developmentally-normal adult-viable animals. Mutants in dmd were homozygous-lethal. Bathing wild-type and capn3b mutants in 0.8% methylcellulose (MC) for 3 days beginning 2 days post-fertilization resulted in significantly pronounced (20-30%) birefringence-detectable muscle abnormalities in capn3b mutant embryos. Evans Blue staining for sarcolemma integrity loss was strongly positive in dmd homozygotes, negative in wild-type embryos, and negative in MC-treated capn3b mutants, suggesting membrane instability is not a primary muscle pathology determinant. Increased birefringence-detected muscle abnormalities in capn3b mutants compared to wild-type animals were observed following induced hypertonia by exposure to cholinesterase inhibitor, azinphos-methyl, reinforcing the MC results. These mutant fish represent a novel tractable model for studying the mechanisms underlying muscle repair and remodeling, and as a preclinical tool for whole-animal therapeutics and behavioral screening in LGMDR1.

Combined 3D Endoanal Ultrasound and Transperineal Ultrasound Improves the Detection of Anal Sphincter Defects.

Anal sphincter injury, mainly due to obstetric or iatrogenic etiology, is the most common cause of fecal incontinence (FI). Three-dimensional endoanal ultrasound (3D EAUS) is used for assessment of the integrity and the degree of anal muscle injury. However, 3D EAUS accuracy may be hampered by regional acoustic effects, such as intravaginal air. Therefore, our aim was to examine whether a combination of transperineal ultrasound (TPUS) and 3D EAUS would improve the accuracy of detection of anal sphincter injury. We prospectively performed 3D EAUS followed by TPUS in every patient evaluated for FI in our clinic between January 2020 and January 2021. The diagnosis of anal muscle defects was assessed in each ultrasound technique by two experienced observers that were blinded to each other's assessments. Interobserver agreement for the results of the 3D EAUS and the TPUS exams was examined. A final diagnosis of anal sphincter defect was based on the results of both ultrasound methods. Discordant results were re-analyzed by the two ultrasonographers for a final consensus on the presence or absence of defects. A total of 108 patients underwent ultrasonographic assessment due to FI (mean age 69 ± 13). Interobserver agreement for the diagnosis of tear on EAUS and TPUS was high (83%) with Cohen's kappa of 0.62. EAUS confirmed anal muscle defects in 56 patients (52%), while TPUS confirmed them in 62 patients (57%). The final consensus agreed on the diagnosis of 63 (58%) muscular defects and 45 (42%) normal exams. The Cohen's kappa coefficient of agreement between the results of the 3D EAUS and the final consensus was 0.63. The combination of 3D EAUS and TPUS improved the detection of anal muscular defects. The application of both techniques for the assessment of the anal integrity should be considered in every patient going through ultrasonographic assessment for anal muscular injury.