Browsing by Author "Childers, Martin K."

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    Chronic administration of a leupeptin-derived calpain inhibitor fails to ameliorate severe muscle pathology in a canine model of Duchenne muscular dystrophy
    Childers, Martin K.; Bogan, Janet R.; Bogan, Daniel J.; Greiner, Hansel; Holder, Melanie; Grange, Robert W.; Kornegay, Joe N. (Frontiers, 2012-01-09)
    Calpains likely play a role in the pathogenesis of Duchenne muscular dystrophy (DMD). Accordingly, calpain inhibition may provide therapeutic benefit to DMD patients. In the present study, we sought to measure benefit from administration of a novel calpain inhibitor, C101, in a canine muscular dystrophy model. Specifically, we tested the hypothesis that treatment with C101 mitigates progressive weakness and severe muscle pathology observed in young dogs with golden retriever muscular dystrophy (GRMD). Young (6-week-old) GRMD dogs were treated daily with either C101 (17 mg/kg twice daily oral dose, n = 9) or placebo (vehicle only, n = 7) for 8 weeks. A battery of functional tests, including tibiotarsal joint angle, muscle/fat composition, and pelvic limb muscle strength were performed at baseline and every 2 weeks during the 8-week study. Results indicate that C101-treated GRMD dogs maintained strength in their cranial pelvic limb muscles (tibiotarsal flexors) while placebo-treated dogs progressively lost strength. However, concomitant improvement was not observed in posterior pelvic limb muscles (tibiotarsal extensors). C101 treatment did not mitigate force drop following repeated eccentric contractions and no improvement was seen in the development of joint contractures, lean muscle mass, or muscle histopathology. Taken together, these data do not support the hypothesis that treatment with C101 mitigates progressive weakness or ameliorates severe muscle pathology observed in young dogs with GRMD.
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    Systemic AAV8-Mediated Gene Therapy Drives Whole-Body Correction of Myotubular Myopathy in Dogs
    Mack, David L.; Poulard, Karine; Goddard, Melissa A.; Latoumerie, Virginie; Snyder, Jessica M.; Grange, Robert W.; Elverman, Matthew R.; Denard, Jerome; Veron, Philippe; Buscara, Laurine; Le Bec, Christine; Hogrel, Jean-Yves; Brezovec, Annie G.; Meng, Hui; Yang, Lin; Liu, Fujun; O'Callaghan, Michael; Gopal, Nikhil; Kelly, Valerie E.; Smith, Barbara K.; Strande, Jennifer L.; Mavilio, Fulvio; Beggs, Alan H.; Mingozzi, Federico; Lawlor, Michael W.; Buj-Bello, Ana; Childers, Martin K. (2017-04-05)
    X-linked myotubular myopathy (XLMTM) results from MTM1 gene mutations and myotubularin deficiency. Most XLMTM patients develop severe muscle weakness leading to respiratory failure and death, typically within 2 years of age. Our objective was to evaluate the efficacy and safety of systemic gene therapy in the p.N155K canine model of XLMTM by performing a dose escalation study. A recombinant adeno-associated virus serotype 8 (rAAV8) vector expressing canine myotubularin (cMTM1) under the muscle-speCific desmin promoter (rAAV8-cMTM1) was administered by simple peripheral venous infusion in XLMTM dogs at 10 weeks of age, when signs of the disease are already present. A comprehensive analysis of survival, limb strength, gait, respiratory function, neurological assessment, histology, vector biodistribution, transgene expression, and immune response was performed over a 9-month study period. Results indicate that systemic gene therapy was well tolerated, prolonged lifespan, and corrected the skeletal musculature throughout the body in a dose-dependent manner, defining an efficacious dose in this large-animal model of the disease. These results support the development of gene therapy clinical trials for XLMTM.
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    Tissue Triage and Freezing for Models of Skeletal Muscle Disease
    Meng, Hui; Janssen, Paul M. L.; Grange, Robert W.; Yang, Lin; Beggs, Alan H.; Swansons, Lindsay C.; Cossette, Stacy A.; Frase, Alison; Childers, Martin K.; Granzier, Henk; Gussoni, Emanuela; Lawlor, Michael W. (Journal of Visualized Experiments, 2014-07-01)
    Skeletal muscle is a unique tissue because of its structure and function, which requires specific protocols for tissue collection to obtain optimal results from functional, cellular, molecular, and pathological evaluations. Due to the subtlety of some pathological abnormalities seen in congenital muscle disorders and the potential for fixation to interfere with the recognition of these features, pathological evaluation of frozen muscle is preferable to fixed muscle when evaluating skeletal muscle for congenital muscle disease. Additionally, the potential to produce severe freezing artifacts in muscle requires specific precautions when freezing skeletal muscle for histological examination that are not commonly used when freezing other tissues. This manuscript describes a protocol for rapid freezing of skeletal muscle using isopentane (2-methylbutane) cooled with liquid nitrogen to preserve optimal skeletal muscle morphology. This procedure is also effective for freezing tissue intended for genetic or protein expression studies. Furthermore, we have integrated our freezing protocol into a broader procedure that also describes preferred methods for the short term triage of tissue for (1) single fiber functional studies and (2) myoblast cell culture, with a focus on the minimum effort necessary to collect tissue and transport it to specialized research or reference labs to complete these studies. Overall, this manuscript provides an outline of how fresh tissue can be effectively distributed for a variety of phenotypic studies and thereby provides standard operating procedures (SOPs) for pathological studies related to congenital muscle disease.