SERCA2a gene transfer improves electrocardiographic performance in aged mdx mice

<p>Abstract</p> <p>Background</p> <p>Cardiomyocyte calcium overloading has been implicated in the pathogenesis of Duchenne muscular dystrophy (DMD) heart disease. The cardiac isoform of sarcoplasmic reticulum calcium ATPase (SERCA2a) plays a major role in removing cytosolic calcium during heart muscle relaxation. Here, we tested the hypothesis that SERCA2a over-expression may mitigate electrocardiography (ECG) abnormalities in old female mdx mice, a murine model of DMD cardiomyopathy.</p> <p>Methods</p> <p>1 × 10¹²viral genome particles/mouse of adeno-associated virus serotype-9 (AAV-9) SERCA2a vector was delivered to 12-m-old female mdx mice (N = 5) via a single bolus tail vein injection. AAV transduction and the ECG profile were examined eight months later.</p> <p>Results</p> <p>The vector genome was detected in the hearts of all AAV-injected mdx mice. Immunofluorescence staining and western blot confirmed SERCA2a over-expression in the mdx heart. Untreated mdx mice showed characteristic tachycardia, PR interval reduction and QT interval prolongation. AAV-9 SERCA2a treatment corrected these ECG abnormalities.</p> <p>Conclusions</p> <p>Our results suggest that AAV SERCA2a therapy may hold great promise in treating dystrophin-deficient heart disease.</p

Gene therapy for Duchenne muscular dystrophy heart disease requires treating both heart and skeletal muscle

Abstract only availableDuchenne muscular dystrophy (DMD) is a lethal muscle wasting disease caused by mutations in the dystrophin gene. Affected children are wheelchair bound by the age of ten and die in their mid-twenties from respiratory and/or cardiac failure. Gene therapy represents a promising avenue for curing DMD. While significant progress has been made for treatment of skeletal muscle disease, few studies have investigated the potential of gene therapy to treat heart disease. A cure for DMD requires rescuing both skeletal and heart muscles. Gene therapy aims to deliver a functional copy of the dystrophin gene to affected muscle cells. However, the dystrophin gene is the largest gene in the body and cannot be effectively delivered with any currently available methods. This led researchers to develop abbreviated versions of the dystrophin gene. The most promising of these genes is a 7 kb mini-dystrophin gene which can completely restore skeletal muscle in the mdx mouse model of DMD. The potential of the mini-dystrophin gene for treating heart disease is uncertain. Cardiac specific mini-dystrophin gene expression improved but did not normalize heart function. To investigate whether the incomplete cardiac rescue is due to skeletal muscle disease, we generated double transgenic male mdx mice which expressed the mini-dystrophin gene in both heart and skeletal muscle. We performed comprehensive skeletal and cardiac muscle testing at 6 months of age. Restoration of skeletal muscle function was confirmed by the grip strength assay. Next, we performed an uphill treadmill assay to gauge overall cardiac performance. Double transgenic mice ran significantly farther than cardiac transgenic mice. Finally, we performed electrocardiographic (ECG) analysis to examine the function of the cardiac conduction system. ECG analysis revealed an improved heart rate for double transgenic mice when compared to heart-only transgenic mice. Taken together, these results support a role for skeletal muscle disease in modulating heart function. Furthermore, these findings highlight the importance of tailoring gene therapy approaches to treat both the heart and skeletal muscle.Life Sciences Undergraduate Research Opportunity Progra

Integrated Modeling System for Water Resources Management of Tarim River Basin

An integrated modeling system has been developed for water resources management of the Tarim River Basin, China. The system coupled remote sensing (RS)/geography information system (GIS) technique with distributed hydrological model to simulate the rainfall runoff, snow melting, and evapotranspiration process of the hydrological cycle. A case study was carried out in the Kaidu watershed. RS/GIS technique was used for effectively accessing, processing, and managing spatial data, such as land use, vegetative cover, soil, topography, precipitation, and evapotranspiration. The model was calibrated and validated against observed discharge for two hydrological stations during the period 1998-2001, and it generally performed well for Nash-Sutcliffe coefficient, water balance coefficient, and correlation coefficient. The Nash-Sutcliffe coefficient was approximately over 0.7 and the water balance error was lower than +/- 5%, indicating reasonable prediction accuracy. A comparison between the conventional and RS-based hydrological models was conducted. Although the two-models exhibit similar performances on runoff and snow melt simulation, the RS-based hydrological model had better performance in the simulation of actual evapotranspiration. Modeling results provide useful decision support for water resources management

An intronic LINE-1 element insertion in the dystrophin gene aborts dystrophin expression and results in Duchenne-like muscular dystrophy in the corgi breed

Duchenne muscular dystrophy (DMD) is a dystrophin-deficient lethal muscle disease. To date, the catastrophic muscle wasting phenotype has only been seen in dystrophin-deficient humans and dogs. While Duchenne-like symptoms have been observed in more than a dozen dog breeds, the mutation is often not known and research colonies are rarely established. Here we report an independent canine DMD model originally derived from the Pembroke Welsh corgi breed. The affected dogs presented clinical signs of muscular dystrophy. Immunostaining revealed the absence of dystrophin and up-regulation of utrophin. Histopathologic examination showed variable fiber size, central nucleation, calcification, fibrosis, neutrophil and macrophage infiltration and cardiac focal vacuolar degeneration. Carrier dogs also displayed mild myopathy. The mutation was identified as a long interspersed repetitive element-1 (LINE-1) insertion in intron 13 which introduced a new exon containing an in-frame stop codon. Similar mutations have been seen in human patients. A colony was generated by crossing carrier females with normal males. Affected puppies had a normal birth weight but they experienced a striking growth delay in the first 5 days. In summary, the new corgi DMD model offers an excellent opportunity to study DMD pathogenesis and to develop novel therapies

The specification and use of 18F-FES PET in breast cancer

Estrogen receptor (ER) is overexpressed in approximately 2/3 of breast cancer patients’ lesions. Noninvasive detection of ER in vivo and dynamic monitoring of ER are crucial for individualized treatment decision-making. 16α-18F-17β-fluoroestradiol (18F-FES) positron emission tomography (PET) has been used in a variety of preclinical and clinical studies to detect ER expression. However, there is still a lack of technical specifications in China. This technical specification was jointly written by domestic experts who had experience of 18F-FES PET imaging and was formed through consultation based on their own experience and research progress in this field both domestically and internationally. This technical specification introduced the synthesis method and quality control requirements of 18F-FES, recommended its clinical application scenarios, and classified them. In addition, experts’ suggestions were provided throughout the entire process systemically and detailly, including pre-imaging preparation, imaging process, image analysis (normal biological distribution, determination of ER positive and negative, lesion detection, influencing factors, false negative and false positive, report requirements), and the limitations of this imaging technique were proposed. The future application prospects were also discussed. This specification aimed to promote the standardized application of 18F-FES PET in China, achieve repeatability and comparability, and provide important molecular imaging technical support for accurate diagnosis and treatment of breast cancer

Marginal Level Dystrophin Expression Improves Clinical Outcome in a Strain of Dystrophin/Utrophin Double Knockout Mice

Inactivation of all utrophin isoforms in dystrophin-deficient mdx mice results in a strain of utrophin knockout mdx (uko/mdx) mice. Uko/mdx mice display severe clinical symptoms and die prematurely as in Duchenne muscular dystrophy (DMD) patients. Here we tested the hypothesis that marginal level dystrophin expression may improve the clinical outcome of uko/mdx mice. It is well established that mdx3cv (3cv) mice express a near-full length dystrophin protein at ∼5% of the normal level. We crossed utrophin-null mutation to the 3cv background. The resulting uko/3cv mice expressed the same level of dystrophin as 3cv mice but utrophin expression was completely eliminated. Surprisingly, uko/3cv mice showed a much milder phenotype. Compared to uko/mdx mice, uko/3cv mice had significantly higher body weight and stronger specific muscle force. Most importantly, uko/3cv outlived uko/mdx mice by several folds. Our results suggest that a threshold level dystrophin expression may provide vital clinical support in a severely affected DMD mouse model. This finding may hold clinical implications in developing novel DMD therapies

Ectopic Catalase Expression in Mitochondria by Adeno-Associated Virus Enhances Exercise Performance in Mice

Oxidative stress is thought to compromise muscle contractility. However, administration of generic antioxidants has failed to convincingly improve performance during exhaustive exercise. One possible explanation may relate to the inability of the supplemented antioxidants to effectively eliminate excessive free radicals at the site of generation. Here, we tested whether delivering catalase to the mitochondria, a site of free radical production in contracting muscle, could improve treadmill performance in C57Bl/6 mice. Recombinant adeno-associated virus serotype-9 (AV.RSV.MCAT) was generated to express a mitochondria-targeted catalase gene. AV.RSV.MCAT was delivered to newborn C57Bl/6 mouse circulation at the dose of 1012 vector genome particles per mouse. Three months later, we observed a ∼2 to 10-fold increase of catalase protein and activity in skeletal muscle and the heart. Subcellular fractionation western blot and double immunofluorescence staining confirmed ectopic catalase expression in the mitochondria. Compared with untreated control mice, absolute running distance and body weight normalized running distance were significantly improved in AV.RSV.MCAT infected mice during exhaustive treadmill running. Interestingly, ex vivo contractility of the extensor digitorum longus muscle was not altered. Taken together, we have demonstrated that forced catalase expression in the mitochondria enhances exercise performance. Our result provides a framework for further elucidating the underlying mechanism. It also raises the hope of applying similar strategies to remove excessive, pathogenic free radicals in certain muscle diseases (such as Duchenne muscular dystrophy) and ameliorate muscle disease

High salt-induced excess reactive oxygen species production resulted in heart tube malformation during gastrulation

An association has been proved between high salt consumption and cardiovascular mortality. In vertebrates, the heart is the first functional organ to be formed. However, it is not clear whether high‐salt exposure has an adverse impact on cardiogenesis. Here we report high‐salt exposure inhibited basement membrane breakdown by affecting RhoA, thus disturbing the expression of Slug/E‐cadherin/N‐cadherin/Laminin and interfering with mesoderm formation during the epithelial‐mesenchymal transition(EMT). Furthermore, the DiI+ cell migration trajectory in vivo and scratch wound assays in vitro indicated that high‐salt exposure restricted cell migration of cardiac progenitors, which was caused by the weaker cytoskeleton structure and unaltered corresponding adhesion junctions at HH7. Besides, down‐regulation of GATA4/5/6, Nkx2.5, TBX5, and Mef2c and up‐regulation of Wnt3a/β‐catenin caused aberrant cardiomyocyte differentiation at HH7 and HH10. High‐salt exposure also inhibited cell proliferation and promoted apoptosis. Most importantly, our study revealed that excessive reactive oxygen species(ROS)generated by high salt disturbed the expression of cardiac‐related genes, detrimentally affecting the above process including EMT, cell migration, differentiation, cell proliferation and apoptosis, which is the major cause of malformation of heart tubes