Spinal muscular atrophy is a devastating motor neuron disease characterized by severe cases of fatal muscle weakness.It is one of the most common genetic causes of mortality among infants aged less than 2 years.Biomar...Spinal muscular atrophy is a devastating motor neuron disease characterized by severe cases of fatal muscle weakness.It is one of the most common genetic causes of mortality among infants aged less than 2 years.Biomarker research is currently receiving more attention,and new candidate biomarkers are constantly being discovered.This review initially discusses the evaluation methods commonly used in clinical practice while briefly outlining their respective pros and cons.We also describe recent advancements in research and the clinical significance of molecular biomarkers for spinal muscular atrophy,which are classified as either specific or non-specific biomarkers.This review provides new insights into the pathogenesis of spinal muscular atrophy,the mechanism of biomarkers in response to drug-modified therapies,the selection of biomarker candidates,and would promote the development of future research.Furthermore,the successful utilization of biomarkers may facilitate the implementation of gene-targeting treatments for patients with spinal muscular atrophy.展开更多
Spinal and bulbar muscular atrophy is a neurodegenerative disease caused by extended CAG trinucleotide repeats in the androgen receptor gene,which encodes a ligand-dependent transcription facto r.The mutant androgen r...Spinal and bulbar muscular atrophy is a neurodegenerative disease caused by extended CAG trinucleotide repeats in the androgen receptor gene,which encodes a ligand-dependent transcription facto r.The mutant androgen receptor protein,characterized by polyglutamine expansion,is prone to misfolding and forms aggregates in both the nucleus and cytoplasm in the brain in spinal and bulbar muscular atrophy patients.These aggregates alter protein-protein interactions and compromise transcriptional activity.In this study,we reported that in both cultured N2a cells and mouse brain,mutant androgen receptor with polyglutamine expansion causes reduced expression of mesencephalic astrocyte-de rived neurotrophic factor.Overexpressio n of mesencephalic astrocyte-derived neurotrophic factor amelio rated the neurotoxicity of mutant androgen receptor through the inhibition of mutant androgen receptor aggregation.Conversely.knocking down endogenous mesencephalic astrocyte-derived neurotrophic factor in the mouse brain exacerbated neuronal damage and mutant androgen receptor aggregation.Our findings suggest that inhibition of mesencephalic astrocyte-derived neurotrophic factor expression by mutant androgen receptor is a potential mechanism underlying neurodegeneration in spinal and bulbar muscular atrophy.展开更多
Mutations in the microrchidia CW-type zinc finger protein 2(MORC2)gene are the causative agent of Charcot-Marie-Tooth disease type 2Z(CMT2Z),and the hotspot mutation p.S87L is associated with a more seve re spinal mus...Mutations in the microrchidia CW-type zinc finger protein 2(MORC2)gene are the causative agent of Charcot-Marie-Tooth disease type 2Z(CMT2Z),and the hotspot mutation p.S87L is associated with a more seve re spinal muscular atrophy-like clinical phenotype.The aims of this study were to determine the mechanism of the severe phenotype caused by the MORC2 p.S87L mutation and to explore potential treatment strategies.Epithelial cells were isolated from urine samples from a spinal muscular atrophy(SMA)-like patient[MORC2 p.S87L),a CMT2Z patient[MORC2 p.Q400R),and a healthy control and induced to generate pluripotent stem cells,which were then differentiated into motor neuron precursor cells.Next-generation RNA sequencing followed by KEGG pathway enrichment analysis revealed that differentially expressed genes involved in the PI3K/Akt and MAP K/ERK signaling pathways were enriched in the p.S87L SMA-like patient group and were significantly downregulated in induced pluripotent stem cells.Reduced proliferation was observed in the induced pluripotent stem cells and motor neuron precursor cells derived from the p.S87L SMA-like patient group compared with the CMT2Z patient group and the healthy control.G0/G1 phase cell cycle arrest was observed in induced pluripotent stem cells derived from the p.S87L SMA-like patient.MORC2 p.S87Lspecific antisense oligonucleotides(p.S87L-ASO-targeting)showed significant efficacy in improving cell prolife ration and activating the PI3K/Akt and MAP K/ERK pathways in induced pluripotent stem cells.Howeve r,p.S87L-ASO-ta rgeting did not rescue prolife ration of motor neuron precursor cells.These findings suggest that downregulation of the PI3K/Akt and MAP K/ERK signaling pathways leading to reduced cell proliferation and G0/G1 phase cell cycle arrest in induced pluripotent stem cells might be the underlying mechanism of the severe p.S87L SMA-like phenotype.p.S87L-ASO-targeting treatment can alleviate disordered cell proliferation in the early stage of pluripotent stem cell induction.展开更多
Spinal muscular atrophy(SMA)is a genetic disorder that primarily affects infants and leads to muscle weakness,atrophy,and paralysis.The main cause is the homozygous mutation or deletion of the SMN1 gene,resulting in i...Spinal muscular atrophy(SMA)is a genetic disorder that primarily affects infants and leads to muscle weakness,atrophy,and paralysis.The main cause is the homozygous mutation or deletion of the SMN1 gene,resulting in inadequate levels of the survival motor neuron(SMN)protein.Approved treatments focus on restoring SMN levels through various approaches,but there is a need for“SMN-independent”therapies that target other pathological processes.Skeletal muscle is closely involved in SMA pathology,with impaired muscle function observed before motor neuron degeneration.Studies have revealed that SMN loss leads to skeletal muscle mitochondrial structural abnormalities,impaired respiration,and accumulation of reactive oxygen species.展开更多
Background:Muscular strength is an important component of physical fitness.We evaluated the relationship between baseline muscular strength and risk of stroke among adults who were aged≥65 years during follow-up.Meth...Background:Muscular strength is an important component of physical fitness.We evaluated the relationship between baseline muscular strength and risk of stroke among adults who were aged≥65 years during follow-up.Methods:We included 7627 healthy adults(mean age=43.9 years,86.0%male)underwent a baseline physical examination between 1980 and 1989.Muscular strength was determined by 1-repetition maximum measures for bench press and leg press and categorized into age-and sex-specific tertiles for each measure.Cardiorespiratory fitness(CRF)was assessed via a maximal treadmill exercise test.Those enrolled in fee-for-service Medicare from 1999 to 2019 were included in the analyses.Associations between baseline strength and stroke outcomes were estimated using a modified Cox proportional hazards model.In a secondary analysis,we examined stroke risk by categories of CRF where Quintile 1=low,Quintiles 2-3=moderate,and Quintiles 4-5=high CRF based on age and sex.Results:After 70,072 person-years of Medicare follow-up,there were 1211 earliest indications of incident stroke.In multivariable analyses,the hazard ratio(95%confidence interval(95%CI))for stroke across bench press categories were 1.0(referent),0.96(0.83-1.11),and 0.89(0.77-1.04),respectively(p trend=0.14).The trend across categories of leg press was also non-significant(p trend=0.79).Adjusted hazard ratio(95%CI)for stroke across ordered CRF categories were 1.0(referent),0.90(0.71-1.13),and 0.72(0.57-0.92)(p trend<0.01).Conclusion:While meeting public health guidelines for muscular strengthening activities is likely to improve muscular strength as well as many health outcomes in older adults,performing such activities may not be helpful in preventing stroke.Conversely,meeting guidelines for aerobic activity is likely to improve CRF and lower stroke risk.展开更多
Introduction: Infantile spinal muscular atrophy (ISA) is an autosomal recessive disease caused by primary degeneration of cells in the anterior horn of the spinal cord, leading to muscle weakness and hypotonia. Its in...Introduction: Infantile spinal muscular atrophy (ISA) is an autosomal recessive disease caused by primary degeneration of cells in the anterior horn of the spinal cord, leading to muscle weakness and hypotonia. Its incidence is estimated at 1 in 6000 births worldwide. In Africa, particularly in Senegal, there are few studies interested on this pathology. We therefore deemed this study necessary, which set itself the objective of describing the diagnostic, therapeutic and progressive aspects of infantile spinal muscular atrophy at the Albert Royer National Children’s Hospital Center in Dakar (CHNEAR). Methodology: We conducted a retrospective descriptive study over a period of two (2) years from December 2020 to December 2022. Included were all hospitalized patients in whom the diagnosis of spinal muscular atrophy was made with or without genetic confirmation. The data were collected on a pre-established form then entered and analyzed with the following software: Excel 2013 and R version 4.1.3. Results: During our study period, 2100 children were hospitalized, the annual incidence was 0.76%. The average age of our patients was 9 ± 9 months with a range of 3 months to 32 months and the median was 6.5 months. The sex ratio was 7. The notion of family consanguinity was found in 62.5% of cases and the notion of ISA in the family in 25% of cases. Hypotonia and respiratory distress were found at the forefront in equal proportions (50% of cases). Electromyogram (EMG) was performed in 3 patients (37.5%). Symptomatic medical treatment was administered in 100% of patients, 04 patients had benefited from respiratory physiotherapy, i.e. 50% of cases, and genetic counseling was carried out in one patient (12.5%). The evolution was immediately favorable in 2 patients or 25% of cases, unfavorable in 75% of cases with a death rate of 50% and the average age of death was 5.5 months ± 1 with extremes ranging from 3 to 7 months. Conclusion: The number of Infantile spinal muscular atrophy cases remains low in hospitals in Dakar. Diagnostic means are still difficult to access. The course is difficult to predict and is often marked in the long term by respiratory difficulties which can be fatal.展开更多
In this case report, we describe the anesthetic management for a 36-year-old G2P0010 at 36 weeks gestation with Spinal Muscular Atrophy Type III who underwent an emergent caesarean section due to fetal footling breech...In this case report, we describe the anesthetic management for a 36-year-old G2P0010 at 36 weeks gestation with Spinal Muscular Atrophy Type III who underwent an emergent caesarean section due to fetal footling breech position. The patient is a wheelchair-bound quadriplegic with kyphoscoliosis and a lack of cough reflex who required nasal continuous noninvasive ventilatory support (CNVS) for chronic hypercapnic respiratory failure. Surgery was done under general anesthesia due to its emergent nature, and the patient was successfully extubated and transitioned to nasal CNVS in the operating room at the end of the case. Postoperative care was provided in the medical intensive care unit for three days without complication and the patient was discharged home uneventfully.展开更多
Objective:To explore the clinical effect of internal fixation and fusion with the paraspinal muscle gap approach in the treatment of spinal fracture patients.Methods:104 spinal fracture patients admitted to Central Ho...Objective:To explore the clinical effect of internal fixation and fusion with the paraspinal muscle gap approach in the treatment of spinal fracture patients.Methods:104 spinal fracture patients admitted to Central Hospital of TCM from October 2022 to April 2024 were selected as the study subjects and were randomly divided into the control group(n=52)and the observation group(n=52)according to the random number table method.The control group was treated with the conventional approach of internal fixation surgery,and the observation group was treated with the paraspinal muscular interspace approach of internal fixation fusion.The two groups’general data,surgical indexes,pain,lumbar spine function,and postoperative complications were observed.Results:The baseline data of the two groups of patients were not statistically significant(all P>0.05)while the intraoperative bleeding,the first postoperative time getting up from bed,and the length of hospital stay of the patients in the observation group were shorter than that of the control group(all P=0.000<0.001),and the duration of the operation was longer than that of the control group(t=2.644,P=0.010<0.05);at 3 months postoperatively,the VAS scores of the patients in the observation group were significantly lower than those in the control group(t=10.768,P=0.000<0.001),and the JOA score was higher than that of the control group(t=6.498,P=0.000<0.001);the total complication rate of patients in the observation group(3/5.77%)was significantly lower than that of the control group(12/23.08%)(χ^(2)=6.310,P=0.012<0.05).Conclusion:In the treatment of spinal fracture patients,compared with the conventional approach to internal fixation surgery,the paraspinal muscular gap approach to internal fixation and fusion treatment is less traumatic,postoperative lumbar spine function recovery is faster,and can reduce the incidence of postoperative complications.展开更多
[ Objective] The aim of this experiment was to explore the effects of different rearing modes on muscle histological traits and muscle ten demess and to provide theoretical basis for regulating chicken meat quality. [...[ Objective] The aim of this experiment was to explore the effects of different rearing modes on muscle histological traits and muscle ten demess and to provide theoretical basis for regulating chicken meat quality. [ Method] The effects of outdoor rearing, indoor rearing and cage rea ring modes on the muscular histological traits and meat tenderness of Hetian chicken at the age of 8 weeks, 12 weeks and 16 weeks were re searched. [Result] The results showed that the breast and thigh muscle fibre diameter and muscle shear force of outdoor rearing chicken were sig nificently higher than that of cage rearing chicken ( P 〈 0.05), and muscle fibre density was significantly lower than that of cage rearing chicken ( P 〈 0.05). With aging, the muscle fibre diameter and shear force increased and muscle fibre density decreased ( P 〈 0.05). The muscle fibre di ameter and shear force of male were higher than that of female. The correlation analysis showed that the breast muscle shear force had a signifi cantly positive relation with fibre diameter and negative relation with fibre density ( P 〈 0.05), but thigh muscle shear force had an insignificantly pos itive relation with fibre diameter and fibre density. [ Condusion] Muscular histological traits varied in different rearing modes, and the outdoor rearing promoted the muscular fibre development and increased the muscular shear force.展开更多
Objective' To study the muscular histological traits and their relationship with meat tenderness in local broilers and provide a theoretical basis for promoting meat quality of broiler. [Methed] The diameter and dens...Objective' To study the muscular histological traits and their relationship with meat tenderness in local broilers and provide a theoretical basis for promoting meat quality of broiler. [Methed] The diameter and density of muscle fiber of three local varieties of chicken (Beijing Fatty broil- er, Fujian Hetian broiler and Taining Black broiler) were detected at the age of 8 weeks, 12 weeks and 16 weeks. And the differences in the diame- ter and density of muscle fiber as well as their relationship with meat tenderness were respectively analyzed with SAS software. [ Resultl Fatty broil- er had the smallest muscle fiber diameter while Hetian broiler the largest; Fatty broiler had the highest muscle fiber density while Hetian broiler the lowest Hetian broiler had the highest muscle shear force of leg muscle while Black broiler the lowest ( P 〈0.05) ; Black broiler had the highest mus- cle shear force of breast muscle while Fatty broiler the lowest (P〈0.05). The correlation analysis showed that the shear force of breast muscle and leg muscle had significantly positive relation with fiber diameter and significantly negative relation with fiber density ( P 〈 0.05). [ Conclusion] Muscu- lar histological traits varied in different local broilers, and the muscular shear force had significantly relation with fiber diameter and density.展开更多
[Objective] This study aimed to investigate the characteristics of deposition of inosine monophosphate (IMP) and intramuscular fat (IMF) in muscles of Jinghai yellow chickens and its crossbred.[Method] The charact...[Objective] This study aimed to investigate the characteristics of deposition of inosine monophosphate (IMP) and intramuscular fat (IMF) in muscles of Jinghai yellow chickens and its crossbred.[Method] The characteristics of IMP and IMF deposition of 112-day-old Jinghai yellow chickens (J×J) and its two different 70-day- old crossbreeds (J×B and B×B) were analyzed. The IMP content in breast muscle and leg muscle were determined by HPLC. [Result] The contents of IMP and cor- rected inosine monophosphate (IMPc) in breast muscle were significantly or ex- tremely significantly higher than that in leg muscle of the chickens in the three groups whether in male or female chickens (P〈0.05 or P〈0.01). There were no sig- nificant difference in the contents of IMP and IMPc between hens and roosters (P〉 0.05). The fresh degree of breast muscle and leg muscle was 96,11%-98.16% and 87.22%-93.07%, respectively. And the fresh degree of breast muscle was higher than that of leg muscle. In the three groups, the IMF content in leg muscle was significantly higher than that in breast muscle whether in male or female chickens (P〈0.05). The contents of IMF in breast muscle and leg muscle were 0.36%-0.75% and 1.84%-2.38%, respectively. The iMP content in breast muscle of chickens in Bx J group was extremely significantly higher than that in breast muscle of chickens in JxJ group (P〈0.01), but the contents of IMPc and iMF of breast muscle and leg muscle of the chickens in the three groups had no significant difference (P〉0.05). [Conclusion] To sum up, the freshness and flavor significantly differ between the breast muscle and leg muscle of chickens, but show no significant difference among the three groups.展开更多
Duchenne and Becker muscular dystrophy(DMD/BMD) are X-linked muscular diseases responsible for over 80% of all muscular dystrophies. Cardiac disease is a common manifestation,not necessarily related to the degree of s...Duchenne and Becker muscular dystrophy(DMD/BMD) are X-linked muscular diseases responsible for over 80% of all muscular dystrophies. Cardiac disease is a common manifestation,not necessarily related to the degree of skeletal myopathy; it may be the predominant manifestation with or without any other evidence of muscular disease. Death is usually due to ventricular dysfunction,heart block or malignant arrhythmias. Not only DMD/BMD patients,but also female carriers may present cardiac involvement. Clinically overt heart failure in dystrophinopathies may be delayed or absent,due to relative physical inactivity. The commonest electrocardiographic findings include conduction defects,arrhythmias(supraventricular or ventricular),hypertrophy and evidence of myocardial necrosis. Echocardiography can assess a marked variability of left ventricular dysfunction,independently of age of onset or mutation groups. Cardiovascular magnetic resonance(CMR) has documented a pattern of epicardial fibrosis in both dystrophinopathies' patients and carriers that can be observed even if overt muscular disease is absent. Recently,new CMR techniques,such as postcontrast myocardial T1 mapping,have been used in Duchenne muscular dystrophy to detect diffuse myocardial fibrosis. A combined approach using clinical assessment and CMR evaluation may motivate early cardioprotective treatment in both patients and asymptomatic carriers and delay the development of serious cardiac complications.展开更多
OBJECTIVE: To identify global research trends in stem cell transplantation for treating Duchenne muscular dystrophy using a bibliometric analysis of Web of Science. DATA RETRIEVAL: We performed a bibliometric analys...OBJECTIVE: To identify global research trends in stem cell transplantation for treating Duchenne muscular dystrophy using a bibliometric analysis of Web of Science. DATA RETRIEVAL: We performed a bibliometric analysis of studies on stem cell transplantation for treating Duchenne muscular dystrophy from 2002 to 2011 retrieved from Web of Science. SELECTION CRITERIA: Inclusion criteria: (a) peer-reviewed published articles on stem cell transplantation for treating Duchenne muscular dystrophy indexed in Web of Science; (b) original research articles, reviews, meeting abstracts, proceedings papers, book chapters, editorial material, and news items; and (c) publication between 2002 and 2011. Exclusion criteria: (a) articles that required manual searching or telephone access; (b) documents that were not published in the public domain; and (c) corrected papers. MAIN OUTCOME MEASURES: (1)Annual publication output; (2) distribution according to subject areas; (3) distribution according to journals; (4) distribution according to country; (5) distribution according to institution; (6) distribution according to institution in China; (7) distribution according to institution that cooperated with Chinese institutions; (8) top-cited articles from 2002 to 2006; (9) top-cited articles from 2007 to 2011. RESULTS: A total of 318 publications on stem cell transplantation for treating Duchenne muscular dystrophy were retrieved from Web of Science from 2002 to 2011, of which almost half derived from American authors and institutes. The number of publications has gradually increased over the past 10 years. Most papers appeared in journals with a focus on gene and molecular research, such as Molecular Therapy, Neuromuscular Disorders, and PLoS One. The 10 most-cited papers from 2002 to 2006 were mostly about different kinds of stem cell transplantation for muscle regeneration, while the 10 most-cited papers from 2007 to 2011 were mostly about new techniques of stem cell transplantation for treating Duchenne muscular dystrophy. CONCLUSION: The publications on stem cell transplantation for treating Duchenne muscular dystrophy were relatively few. It also needs more research to confirm that stem cell therapy is a reliable treatment for Duchenne muscular dystrophy.展开更多
Adipose-derived stem cells have been shown to promote peripheral nerve regeneration through the paracrine secretion of neurotrophic factors. However, it is unclear whether these cells can promote myogenic differentiat...Adipose-derived stem cells have been shown to promote peripheral nerve regeneration through the paracrine secretion of neurotrophic factors. However, it is unclear whether these cells can promote myogenic differentiation in muscular dystrophy. Adipose-derived stem cells (6 × 106) were injected into the gastrocnemius muscle of mdx mice at various sites. Dystrophin expression was found in the muscle fibers. Phosphorylation levels of Akt, mammalian target of rapamycin (mTOR), eIF-4E binding protein 1 and $6 kinase 1 were increased, and the Akt/mTOR pathway was activated. Simultaneously, myogenin levels were increased, whereas cleaved caspase 3 and vimentin levels were decreased. Necrosis and fibrosis were reduced in the muscle fibers. These findings suggest that adipose-derived stem cells promote the re- generation and survival of muscle cells by inhibiting apoptosis and fibrosis, thereby alleviating muscle damage in muscular dystrophy.展开更多
Quantitative magnetic resonance image(MRI)in individual muscles may be useful for monitoring disease progression in Duchenne muscular dystrophy(DMD).The purpose of this study w批to measure丁2 relaxation time of thigh ...Quantitative magnetic resonance image(MRI)in individual muscles may be useful for monitoring disease progression in Duchenne muscular dystrophy(DMD).The purpose of this study w批to measure丁2 relaxation time of thigh muscles in children with DMD and healthy boys,and to correlate the T2 relaxation time of muscles with the fat fraction(FF)at quantitative magnetic resonance and results of clinical assessment.Thirty-two boys with DMD and 18 healthy boys were evaluated with T2 mapping and three-point Dixon MRI.Age,body mass index(BMI),muscle strength assessment,timed functional tests(time to walk or run 10 metres,rise from the floor and ascend four stairs),and the North Star Ambulatory Assessment(NSAA)were evaluated.Spearman’s correlation was used to assess the relationships between FF and clinical assessments and T2 relaxation time.The mean T2 relaxation time of thigh muscles in DMD was significantly longer than that in the control group(P<0.05),except for the gracilis(P=0.952).The gracilis,sartorius and adductor longus were relatively spared by fatty infiltration in DMD patients.The T2 relaxation time was correlated significantly with the mean FF in all muscles.Age,BMI,total muscle strength score,timed functional tests and NSAA were significantly correlated with the overall mean T2 relaxation time.T2 mapping may prove clinically useful in monitoring muscle changes as a result of the disease process and in predicting the outcome of DMD patients.展开更多
Becker muscular dystrophy(BMD) is an X-linked recessive disorder involving mutations of the dystrophin gene. Cardiac involvement in BMD has been described and cardiomyopathy represents the number one cause of death in...Becker muscular dystrophy(BMD) is an X-linked recessive disorder involving mutations of the dystrophin gene. Cardiac involvement in BMD has been described and cardiomyopathy represents the number one cause of death in these patients. In this paper, the pathophysiology, clinical evaluations and management of cardiomyopathy in patients with BMD will be discussed.展开更多
BACKGROUND Duchenne muscular dystrophy(DMD),which is caused by a mutation/deletion in the dystrophin gene on the X-chromosome,is the most common type of neuromuscular disorder in pediatrics.Skeletal muscle weakness pr...BACKGROUND Duchenne muscular dystrophy(DMD),which is caused by a mutation/deletion in the dystrophin gene on the X-chromosome,is the most common type of neuromuscular disorder in pediatrics.Skeletal muscle weakness progressively develops in DMD patients and usually leads to respiratory failure in the early adolescent years.Cardiac muscle is frequently affected in DMD patients,which leads to a high burden of cardiomyopathy and heart failure.In the era of improved respiratory care,cardiac deaths are becoming the major cause of mortality in DMD patients.CASE SUMMARY We report the case of a 15-year-old boy who presented to the hospital due to recurrent orthopnea for 6 mo and palpitations for 4 mo.He was diagnosed with progressive muscular dystrophy at the age of 3 years and was confined to a wheelchair at 12 years.He was prescribed diuretics and digoxin at the outpatient clinic;however,his symptoms did not resolve.Sacubitril/valsartan was added 1 mo prior to presentation,but he experienced recurrent episodes of palpitations.The electrocardiogram showed atrial tachycardia with a heart rate of 201 bpm,and he was then hospitalized.Hypotension was found following the administration of sacubitril/valsartan tablets;he could not tolerate even a small dose,always developing tachyarrhythmia.His symptoms were relieved after discontinuing sacubitril/valsartan,and his heart rate was controlled by a small dose of metoprolol tartrate and digoxin.Atrial tachycardia spontaneously converted in this patient,and his symptoms attenuated in the following 6 mo,without palpitation episodes.CONCLUSION Blood pressure should be closely monitored in DMD patients with advanced heart failure when taking sacubitril/valsartan.展开更多
Due to their relative abundance,stable biological properties and excellent reproductive activity,umbilical cord mesenchymal stem cells have previously been utilized for the treatment of Duchenne muscular dystrophy,whi...Due to their relative abundance,stable biological properties and excellent reproductive activity,umbilical cord mesenchymal stem cells have previously been utilized for the treatment of Duchenne muscular dystrophy,which is a muscular atrophy disease.Three patients who were clinically and pathologically diagnosed with Duchenne muscular dystrophy were transplanted with umbilical cord mesenchymal stem cells by intravenous infusion,in combination with multi-point intramuscular injection.They were followed up for 12 months after cell transplantation.Results showed that clinical symptoms significantly improved,daily living activity and muscle strength were enhanced,the sero-enzyme,electromyogram,and MRI scans showed improvement,and dystrophin was expressed in the muscle cell membrane.Hematoxylin-eosin staining of a muscle biopsy revealed that muscle fibers were well arranged,fibrous degeneration was alleviated,and fat infiltration was improved.These pieces of evidence suggest that umbilical cord mesenchymal stem cell transplantation can be considered as a new regimen for Duchenne muscular dystrophy.展开更多
基金supported by the Collaborative Innovation Center for Clinical and Translational Science by Chinese Ministry of Education&Shanghai,No.CCTS-2022205the“Double World-Class Project”of Shanghai Jiaotong University School of Medicine(both to JZ)。
文摘Spinal muscular atrophy is a devastating motor neuron disease characterized by severe cases of fatal muscle weakness.It is one of the most common genetic causes of mortality among infants aged less than 2 years.Biomarker research is currently receiving more attention,and new candidate biomarkers are constantly being discovered.This review initially discusses the evaluation methods commonly used in clinical practice while briefly outlining their respective pros and cons.We also describe recent advancements in research and the clinical significance of molecular biomarkers for spinal muscular atrophy,which are classified as either specific or non-specific biomarkers.This review provides new insights into the pathogenesis of spinal muscular atrophy,the mechanism of biomarkers in response to drug-modified therapies,the selection of biomarker candidates,and would promote the development of future research.Furthermore,the successful utilization of biomarkers may facilitate the implementation of gene-targeting treatments for patients with spinal muscular atrophy.
基金supported by the National Key R&D Program of China,No.2021YFA0805200(to SY)the National Natural Science Foundation of China,No.31970954(to SY)two grants from the Department of Science and Technology of Guangdong Province,Nos.2021ZT09Y007,2020B121201006(both to XJL)。
文摘Spinal and bulbar muscular atrophy is a neurodegenerative disease caused by extended CAG trinucleotide repeats in the androgen receptor gene,which encodes a ligand-dependent transcription facto r.The mutant androgen receptor protein,characterized by polyglutamine expansion,is prone to misfolding and forms aggregates in both the nucleus and cytoplasm in the brain in spinal and bulbar muscular atrophy patients.These aggregates alter protein-protein interactions and compromise transcriptional activity.In this study,we reported that in both cultured N2a cells and mouse brain,mutant androgen receptor with polyglutamine expansion causes reduced expression of mesencephalic astrocyte-de rived neurotrophic factor.Overexpressio n of mesencephalic astrocyte-derived neurotrophic factor amelio rated the neurotoxicity of mutant androgen receptor through the inhibition of mutant androgen receptor aggregation.Conversely.knocking down endogenous mesencephalic astrocyte-derived neurotrophic factor in the mouse brain exacerbated neuronal damage and mutant androgen receptor aggregation.Our findings suggest that inhibition of mesencephalic astrocyte-derived neurotrophic factor expression by mutant androgen receptor is a potential mechanism underlying neurodegeneration in spinal and bulbar muscular atrophy.
基金supported by the National Natural Science Foundation of China,Nos.82171172(to RZ)and 81771366(to RZ)Fundamental Research Funds for the Central Universities of Central South University,Nos.2021zzts1095(to SZ)and 2022zzts0832(to HY)。
文摘Mutations in the microrchidia CW-type zinc finger protein 2(MORC2)gene are the causative agent of Charcot-Marie-Tooth disease type 2Z(CMT2Z),and the hotspot mutation p.S87L is associated with a more seve re spinal muscular atrophy-like clinical phenotype.The aims of this study were to determine the mechanism of the severe phenotype caused by the MORC2 p.S87L mutation and to explore potential treatment strategies.Epithelial cells were isolated from urine samples from a spinal muscular atrophy(SMA)-like patient[MORC2 p.S87L),a CMT2Z patient[MORC2 p.Q400R),and a healthy control and induced to generate pluripotent stem cells,which were then differentiated into motor neuron precursor cells.Next-generation RNA sequencing followed by KEGG pathway enrichment analysis revealed that differentially expressed genes involved in the PI3K/Akt and MAP K/ERK signaling pathways were enriched in the p.S87L SMA-like patient group and were significantly downregulated in induced pluripotent stem cells.Reduced proliferation was observed in the induced pluripotent stem cells and motor neuron precursor cells derived from the p.S87L SMA-like patient group compared with the CMT2Z patient group and the healthy control.G0/G1 phase cell cycle arrest was observed in induced pluripotent stem cells derived from the p.S87L SMA-like patient.MORC2 p.S87Lspecific antisense oligonucleotides(p.S87L-ASO-targeting)showed significant efficacy in improving cell prolife ration and activating the PI3K/Akt and MAP K/ERK pathways in induced pluripotent stem cells.Howeve r,p.S87L-ASO-ta rgeting did not rescue prolife ration of motor neuron precursor cells.These findings suggest that downregulation of the PI3K/Akt and MAP K/ERK signaling pathways leading to reduced cell proliferation and G0/G1 phase cell cycle arrest in induced pluripotent stem cells might be the underlying mechanism of the severe p.S87L SMA-like phenotype.p.S87L-ASO-targeting treatment can alleviate disordered cell proliferation in the early stage of pluripotent stem cell induction.
基金supported by AFM-Telethon2013/Project 16662(to CB).
文摘Spinal muscular atrophy(SMA)is a genetic disorder that primarily affects infants and leads to muscle weakness,atrophy,and paralysis.The main cause is the homozygous mutation or deletion of the SMN1 gene,resulting in inadequate levels of the survival motor neuron(SMN)protein.Approved treatments focus on restoring SMN levels through various approaches,but there is a need for“SMN-independent”therapies that target other pathological processes.Skeletal muscle is closely involved in SMA pathology,with impaired muscle function observed before motor neuron degeneration.Studies have revealed that SMN loss leads to skeletal muscle mitochondrial structural abnormalities,impaired respiration,and accumulation of reactive oxygen species.
文摘Background:Muscular strength is an important component of physical fitness.We evaluated the relationship between baseline muscular strength and risk of stroke among adults who were aged≥65 years during follow-up.Methods:We included 7627 healthy adults(mean age=43.9 years,86.0%male)underwent a baseline physical examination between 1980 and 1989.Muscular strength was determined by 1-repetition maximum measures for bench press and leg press and categorized into age-and sex-specific tertiles for each measure.Cardiorespiratory fitness(CRF)was assessed via a maximal treadmill exercise test.Those enrolled in fee-for-service Medicare from 1999 to 2019 were included in the analyses.Associations between baseline strength and stroke outcomes were estimated using a modified Cox proportional hazards model.In a secondary analysis,we examined stroke risk by categories of CRF where Quintile 1=low,Quintiles 2-3=moderate,and Quintiles 4-5=high CRF based on age and sex.Results:After 70,072 person-years of Medicare follow-up,there were 1211 earliest indications of incident stroke.In multivariable analyses,the hazard ratio(95%confidence interval(95%CI))for stroke across bench press categories were 1.0(referent),0.96(0.83-1.11),and 0.89(0.77-1.04),respectively(p trend=0.14).The trend across categories of leg press was also non-significant(p trend=0.79).Adjusted hazard ratio(95%CI)for stroke across ordered CRF categories were 1.0(referent),0.90(0.71-1.13),and 0.72(0.57-0.92)(p trend<0.01).Conclusion:While meeting public health guidelines for muscular strengthening activities is likely to improve muscular strength as well as many health outcomes in older adults,performing such activities may not be helpful in preventing stroke.Conversely,meeting guidelines for aerobic activity is likely to improve CRF and lower stroke risk.
文摘Introduction: Infantile spinal muscular atrophy (ISA) is an autosomal recessive disease caused by primary degeneration of cells in the anterior horn of the spinal cord, leading to muscle weakness and hypotonia. Its incidence is estimated at 1 in 6000 births worldwide. In Africa, particularly in Senegal, there are few studies interested on this pathology. We therefore deemed this study necessary, which set itself the objective of describing the diagnostic, therapeutic and progressive aspects of infantile spinal muscular atrophy at the Albert Royer National Children’s Hospital Center in Dakar (CHNEAR). Methodology: We conducted a retrospective descriptive study over a period of two (2) years from December 2020 to December 2022. Included were all hospitalized patients in whom the diagnosis of spinal muscular atrophy was made with or without genetic confirmation. The data were collected on a pre-established form then entered and analyzed with the following software: Excel 2013 and R version 4.1.3. Results: During our study period, 2100 children were hospitalized, the annual incidence was 0.76%. The average age of our patients was 9 ± 9 months with a range of 3 months to 32 months and the median was 6.5 months. The sex ratio was 7. The notion of family consanguinity was found in 62.5% of cases and the notion of ISA in the family in 25% of cases. Hypotonia and respiratory distress were found at the forefront in equal proportions (50% of cases). Electromyogram (EMG) was performed in 3 patients (37.5%). Symptomatic medical treatment was administered in 100% of patients, 04 patients had benefited from respiratory physiotherapy, i.e. 50% of cases, and genetic counseling was carried out in one patient (12.5%). The evolution was immediately favorable in 2 patients or 25% of cases, unfavorable in 75% of cases with a death rate of 50% and the average age of death was 5.5 months ± 1 with extremes ranging from 3 to 7 months. Conclusion: The number of Infantile spinal muscular atrophy cases remains low in hospitals in Dakar. Diagnostic means are still difficult to access. The course is difficult to predict and is often marked in the long term by respiratory difficulties which can be fatal.
文摘In this case report, we describe the anesthetic management for a 36-year-old G2P0010 at 36 weeks gestation with Spinal Muscular Atrophy Type III who underwent an emergent caesarean section due to fetal footling breech position. The patient is a wheelchair-bound quadriplegic with kyphoscoliosis and a lack of cough reflex who required nasal continuous noninvasive ventilatory support (CNVS) for chronic hypercapnic respiratory failure. Surgery was done under general anesthesia due to its emergent nature, and the patient was successfully extubated and transitioned to nasal CNVS in the operating room at the end of the case. Postoperative care was provided in the medical intensive care unit for three days without complication and the patient was discharged home uneventfully.
基金Hebei Province’s 2020 Medical Scientific Research Topics“Clinical Study on Simultaneous Treatment of Multi-Segment Lumbar Disc Herniation with Transforaminal Endoscopy”(Project No.:1951ZF073)。
文摘Objective:To explore the clinical effect of internal fixation and fusion with the paraspinal muscle gap approach in the treatment of spinal fracture patients.Methods:104 spinal fracture patients admitted to Central Hospital of TCM from October 2022 to April 2024 were selected as the study subjects and were randomly divided into the control group(n=52)and the observation group(n=52)according to the random number table method.The control group was treated with the conventional approach of internal fixation surgery,and the observation group was treated with the paraspinal muscular interspace approach of internal fixation fusion.The two groups’general data,surgical indexes,pain,lumbar spine function,and postoperative complications were observed.Results:The baseline data of the two groups of patients were not statistically significant(all P>0.05)while the intraoperative bleeding,the first postoperative time getting up from bed,and the length of hospital stay of the patients in the observation group were shorter than that of the control group(all P=0.000<0.001),and the duration of the operation was longer than that of the control group(t=2.644,P=0.010<0.05);at 3 months postoperatively,the VAS scores of the patients in the observation group were significantly lower than those in the control group(t=10.768,P=0.000<0.001),and the JOA score was higher than that of the control group(t=6.498,P=0.000<0.001);the total complication rate of patients in the observation group(3/5.77%)was significantly lower than that of the control group(12/23.08%)(χ^(2)=6.310,P=0.012<0.05).Conclusion:In the treatment of spinal fracture patients,compared with the conventional approach to internal fixation surgery,the paraspinal muscular gap approach to internal fixation and fusion treatment is less traumatic,postoperative lumbar spine function recovery is faster,and can reduce the incidence of postoperative complications.
文摘[ Objective] The aim of this experiment was to explore the effects of different rearing modes on muscle histological traits and muscle ten demess and to provide theoretical basis for regulating chicken meat quality. [ Method] The effects of outdoor rearing, indoor rearing and cage rea ring modes on the muscular histological traits and meat tenderness of Hetian chicken at the age of 8 weeks, 12 weeks and 16 weeks were re searched. [Result] The results showed that the breast and thigh muscle fibre diameter and muscle shear force of outdoor rearing chicken were sig nificently higher than that of cage rearing chicken ( P 〈 0.05), and muscle fibre density was significantly lower than that of cage rearing chicken ( P 〈 0.05). With aging, the muscle fibre diameter and shear force increased and muscle fibre density decreased ( P 〈 0.05). The muscle fibre di ameter and shear force of male were higher than that of female. The correlation analysis showed that the breast muscle shear force had a signifi cantly positive relation with fibre diameter and negative relation with fibre density ( P 〈 0.05), but thigh muscle shear force had an insignificantly pos itive relation with fibre diameter and fibre density. [ Condusion] Muscular histological traits varied in different rearing modes, and the outdoor rearing promoted the muscular fibre development and increased the muscular shear force.
文摘Objective' To study the muscular histological traits and their relationship with meat tenderness in local broilers and provide a theoretical basis for promoting meat quality of broiler. [Methed] The diameter and density of muscle fiber of three local varieties of chicken (Beijing Fatty broil- er, Fujian Hetian broiler and Taining Black broiler) were detected at the age of 8 weeks, 12 weeks and 16 weeks. And the differences in the diame- ter and density of muscle fiber as well as their relationship with meat tenderness were respectively analyzed with SAS software. [ Resultl Fatty broil- er had the smallest muscle fiber diameter while Hetian broiler the largest; Fatty broiler had the highest muscle fiber density while Hetian broiler the lowest Hetian broiler had the highest muscle shear force of leg muscle while Black broiler the lowest ( P 〈0.05) ; Black broiler had the highest mus- cle shear force of breast muscle while Fatty broiler the lowest (P〈0.05). The correlation analysis showed that the shear force of breast muscle and leg muscle had significantly positive relation with fiber diameter and significantly negative relation with fiber density ( P 〈 0.05). [ Conclusion] Muscu- lar histological traits varied in different local broilers, and the muscular shear force had significantly relation with fiber diameter and density.
基金Supported by the Science and Technology Supporting Project (Agriculture) of Jiangsu Province (BE2011452)the Special Fund Project of the National Broiler Industry Technology System (CARS-42-G23)a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)~~
文摘[Objective] This study aimed to investigate the characteristics of deposition of inosine monophosphate (IMP) and intramuscular fat (IMF) in muscles of Jinghai yellow chickens and its crossbred.[Method] The characteristics of IMP and IMF deposition of 112-day-old Jinghai yellow chickens (J×J) and its two different 70-day- old crossbreeds (J×B and B×B) were analyzed. The IMP content in breast muscle and leg muscle were determined by HPLC. [Result] The contents of IMP and cor- rected inosine monophosphate (IMPc) in breast muscle were significantly or ex- tremely significantly higher than that in leg muscle of the chickens in the three groups whether in male or female chickens (P〈0.05 or P〈0.01). There were no sig- nificant difference in the contents of IMP and IMPc between hens and roosters (P〉 0.05). The fresh degree of breast muscle and leg muscle was 96,11%-98.16% and 87.22%-93.07%, respectively. And the fresh degree of breast muscle was higher than that of leg muscle. In the three groups, the IMF content in leg muscle was significantly higher than that in breast muscle whether in male or female chickens (P〈0.05). The contents of IMF in breast muscle and leg muscle were 0.36%-0.75% and 1.84%-2.38%, respectively. The iMP content in breast muscle of chickens in Bx J group was extremely significantly higher than that in breast muscle of chickens in JxJ group (P〈0.01), but the contents of IMPc and iMF of breast muscle and leg muscle of the chickens in the three groups had no significant difference (P〉0.05). [Conclusion] To sum up, the freshness and flavor significantly differ between the breast muscle and leg muscle of chickens, but show no significant difference among the three groups.
文摘Duchenne and Becker muscular dystrophy(DMD/BMD) are X-linked muscular diseases responsible for over 80% of all muscular dystrophies. Cardiac disease is a common manifestation,not necessarily related to the degree of skeletal myopathy; it may be the predominant manifestation with or without any other evidence of muscular disease. Death is usually due to ventricular dysfunction,heart block or malignant arrhythmias. Not only DMD/BMD patients,but also female carriers may present cardiac involvement. Clinically overt heart failure in dystrophinopathies may be delayed or absent,due to relative physical inactivity. The commonest electrocardiographic findings include conduction defects,arrhythmias(supraventricular or ventricular),hypertrophy and evidence of myocardial necrosis. Echocardiography can assess a marked variability of left ventricular dysfunction,independently of age of onset or mutation groups. Cardiovascular magnetic resonance(CMR) has documented a pattern of epicardial fibrosis in both dystrophinopathies' patients and carriers that can be observed even if overt muscular disease is absent. Recently,new CMR techniques,such as postcontrast myocardial T1 mapping,have been used in Duchenne muscular dystrophy to detect diffuse myocardial fibrosis. A combined approach using clinical assessment and CMR evaluation may motivate early cardioprotective treatment in both patients and asymptomatic carriers and delay the development of serious cardiac complications.
基金supported by the Key TechnologiesR & D Program of Liaoning Province,No.2008225009.
文摘OBJECTIVE: To identify global research trends in stem cell transplantation for treating Duchenne muscular dystrophy using a bibliometric analysis of Web of Science. DATA RETRIEVAL: We performed a bibliometric analysis of studies on stem cell transplantation for treating Duchenne muscular dystrophy from 2002 to 2011 retrieved from Web of Science. SELECTION CRITERIA: Inclusion criteria: (a) peer-reviewed published articles on stem cell transplantation for treating Duchenne muscular dystrophy indexed in Web of Science; (b) original research articles, reviews, meeting abstracts, proceedings papers, book chapters, editorial material, and news items; and (c) publication between 2002 and 2011. Exclusion criteria: (a) articles that required manual searching or telephone access; (b) documents that were not published in the public domain; and (c) corrected papers. MAIN OUTCOME MEASURES: (1)Annual publication output; (2) distribution according to subject areas; (3) distribution according to journals; (4) distribution according to country; (5) distribution according to institution; (6) distribution according to institution in China; (7) distribution according to institution that cooperated with Chinese institutions; (8) top-cited articles from 2002 to 2006; (9) top-cited articles from 2007 to 2011. RESULTS: A total of 318 publications on stem cell transplantation for treating Duchenne muscular dystrophy were retrieved from Web of Science from 2002 to 2011, of which almost half derived from American authors and institutes. The number of publications has gradually increased over the past 10 years. Most papers appeared in journals with a focus on gene and molecular research, such as Molecular Therapy, Neuromuscular Disorders, and PLoS One. The 10 most-cited papers from 2002 to 2006 were mostly about different kinds of stem cell transplantation for muscle regeneration, while the 10 most-cited papers from 2007 to 2011 were mostly about new techniques of stem cell transplantation for treating Duchenne muscular dystrophy. CONCLUSION: The publications on stem cell transplantation for treating Duchenne muscular dystrophy were relatively few. It also needs more research to confirm that stem cell therapy is a reliable treatment for Duchenne muscular dystrophy.
基金supported by the National Natural Science Foundation of China,No.30370510,30870851,81271401the Joint Fund of National Natural Science Foundation of ChinaNatural Science Foundation of Guangdong Province of China,No.U1032004
文摘Adipose-derived stem cells have been shown to promote peripheral nerve regeneration through the paracrine secretion of neurotrophic factors. However, it is unclear whether these cells can promote myogenic differentiation in muscular dystrophy. Adipose-derived stem cells (6 × 106) were injected into the gastrocnemius muscle of mdx mice at various sites. Dystrophin expression was found in the muscle fibers. Phosphorylation levels of Akt, mammalian target of rapamycin (mTOR), eIF-4E binding protein 1 and $6 kinase 1 were increased, and the Akt/mTOR pathway was activated. Simultaneously, myogenin levels were increased, whereas cleaved caspase 3 and vimentin levels were decreased. Necrosis and fibrosis were reduced in the muscle fibers. These findings suggest that adipose-derived stem cells promote the re- generation and survival of muscle cells by inhibiting apoptosis and fibrosis, thereby alleviating muscle damage in muscular dystrophy.
文摘Quantitative magnetic resonance image(MRI)in individual muscles may be useful for monitoring disease progression in Duchenne muscular dystrophy(DMD).The purpose of this study w批to measure丁2 relaxation time of thigh muscles in children with DMD and healthy boys,and to correlate the T2 relaxation time of muscles with the fat fraction(FF)at quantitative magnetic resonance and results of clinical assessment.Thirty-two boys with DMD and 18 healthy boys were evaluated with T2 mapping and three-point Dixon MRI.Age,body mass index(BMI),muscle strength assessment,timed functional tests(time to walk or run 10 metres,rise from the floor and ascend four stairs),and the North Star Ambulatory Assessment(NSAA)were evaluated.Spearman’s correlation was used to assess the relationships between FF and clinical assessments and T2 relaxation time.The mean T2 relaxation time of thigh muscles in DMD was significantly longer than that in the control group(P<0.05),except for the gracilis(P=0.952).The gracilis,sartorius and adductor longus were relatively spared by fatty infiltration in DMD patients.The T2 relaxation time was correlated significantly with the mean FF in all muscles.Age,BMI,total muscle strength score,timed functional tests and NSAA were significantly correlated with the overall mean T2 relaxation time.T2 mapping may prove clinically useful in monitoring muscle changes as a result of the disease process and in predicting the outcome of DMD patients.
文摘Becker muscular dystrophy(BMD) is an X-linked recessive disorder involving mutations of the dystrophin gene. Cardiac involvement in BMD has been described and cardiomyopathy represents the number one cause of death in these patients. In this paper, the pathophysiology, clinical evaluations and management of cardiomyopathy in patients with BMD will be discussed.
基金Natural Science Foundation of Zhejiang Province,No.LQ16H020004
文摘BACKGROUND Duchenne muscular dystrophy(DMD),which is caused by a mutation/deletion in the dystrophin gene on the X-chromosome,is the most common type of neuromuscular disorder in pediatrics.Skeletal muscle weakness progressively develops in DMD patients and usually leads to respiratory failure in the early adolescent years.Cardiac muscle is frequently affected in DMD patients,which leads to a high burden of cardiomyopathy and heart failure.In the era of improved respiratory care,cardiac deaths are becoming the major cause of mortality in DMD patients.CASE SUMMARY We report the case of a 15-year-old boy who presented to the hospital due to recurrent orthopnea for 6 mo and palpitations for 4 mo.He was diagnosed with progressive muscular dystrophy at the age of 3 years and was confined to a wheelchair at 12 years.He was prescribed diuretics and digoxin at the outpatient clinic;however,his symptoms did not resolve.Sacubitril/valsartan was added 1 mo prior to presentation,but he experienced recurrent episodes of palpitations.The electrocardiogram showed atrial tachycardia with a heart rate of 201 bpm,and he was then hospitalized.Hypotension was found following the administration of sacubitril/valsartan tablets;he could not tolerate even a small dose,always developing tachyarrhythmia.His symptoms were relieved after discontinuing sacubitril/valsartan,and his heart rate was controlled by a small dose of metoprolol tartrate and digoxin.Atrial tachycardia spontaneously converted in this patient,and his symptoms attenuated in the following 6 mo,without palpitation episodes.CONCLUSION Blood pressure should be closely monitored in DMD patients with advanced heart failure when taking sacubitril/valsartan.
基金a grant by Key Projects of Liaoning Province, No. 2008225009
文摘Due to their relative abundance,stable biological properties and excellent reproductive activity,umbilical cord mesenchymal stem cells have previously been utilized for the treatment of Duchenne muscular dystrophy,which is a muscular atrophy disease.Three patients who were clinically and pathologically diagnosed with Duchenne muscular dystrophy were transplanted with umbilical cord mesenchymal stem cells by intravenous infusion,in combination with multi-point intramuscular injection.They were followed up for 12 months after cell transplantation.Results showed that clinical symptoms significantly improved,daily living activity and muscle strength were enhanced,the sero-enzyme,electromyogram,and MRI scans showed improvement,and dystrophin was expressed in the muscle cell membrane.Hematoxylin-eosin staining of a muscle biopsy revealed that muscle fibers were well arranged,fibrous degeneration was alleviated,and fat infiltration was improved.These pieces of evidence suggest that umbilical cord mesenchymal stem cell transplantation can be considered as a new regimen for Duchenne muscular dystrophy.