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G.P.8.13 Accelerometry, a new tool to assess gait quality in dystrophin-deficient dogs
Abstracts / Neuromuscular Disorders 18 (2008) 724–833
785
loss of force. This study highlights deleterious repercussions of the association of CsA+Prednisone at immunosuppressive levels on GRMD dogs. These data are a keystone for the analysis of results in therapeutic trials. Thus, a force improvement can be interpreted with certainty as a gain of function due to the specific treatment, and not to the immunosuppressive regimen.
LGMD2D patients carrying mutations that impair a-sarcoglycan trafficking.
doi:10.1016/j.nmd.2008.06.209
G.P.8.13
G.P.8.11
Accelerometry, a new tool to assess gait quality in dystrophin-deficient dogs I. Barthe´le´my 1; E. Barrey 2; T. Voit 2; J.L. Thibaud 1; A. Uriarte 1; S. Blot 1; J.Y. Hogrel 3 1 ENVA, Laboratoire de Neurobiologie, Maisons-Alfort, France; 2 Genopole - INSERM 902, Lab. d’Etude de la Physiologie de l’Exercice, Evry, France; 3 GH Pitie´-Salpeˆtrie`re, Institut de myologie, Paris, France
Steroid treatment causes deterioration of myocardial function in the deltasarcoglycan deficient mouse model for dilated cardiomyopathy R. Bauer 1; G.A. Mac Gowan 2; A. Blain 1; K. Bushby 1; V.W. Straub 1 1 Newcastle University, Institute of Human Genetics, Newcastle upon Tyne, United Kingdom; 2 Freeman Hospital, Department of Cardiology, Newcastle upon Tyne, United Kingdom As oral corticosteroids have a beneficial effect on muscle strength in Duchenne muscular dystrophy (DMD), it has been suggested that they may also be a useful treatment in the pathologically related sarcoglycanopathies. The delta-sarcoglycan deficient mouse (Sgcd-null) is a model for both limb girdle muscular dystrophy 2F (LGMD2F) and dilated cardiomyopathy. Our assessment of in vivo cardiac function by pressure volume loops using a conductance catheter revealed a well compensated cardiomyopathy at baseline in Sgcd-null mice with decreased myocardial contractility, increased preload and decreased afterload, maintaining a high cardiac output. To study the effect of oral corticosteroids on cardiac function we treated 8 week old Sgcd-null mice with prednisolone (1.5 mg/kg/day orally) for 8 weeks. Cardiac haemodynamics surprisingly did not improve in prednisolone treated mice but instead deteriorated with evidence of ventricular stiffening. On histology after steroid treatment there was increased myocardial cell damage reflected by higher Evans blue dye uptake (sarcolemmal injury) and increased myocardial fibrosis. In summary, prednisolone led to a decompensation of cardiac haemodynamics in Sgcd-null mice and induced additional cardiac damage. On the basis of these findings, although current clinical outcomes do not indicate a similar problem in patients on long-term corticosteroids, we conclude that careful cardiac monitoring is clearly indicated. doi:10.1016/j.nmd.2008.06.210
doi:10.1016/j.nmd.2008.06.211
Dystrophin-deficient dogs, as canine replicas of DMD patients, represent the choice model to evaluate systemic therapeutic strategies. In this context, the development of a quantitative, discriminating and non-invasive method of gait quality assessment is essential. Accelerometry, a technique based on 3D recording of accelerations, is the method we have chosen to develop, because it seems to be easy to perform in dogs and a source of several quantified parameters. In this aim, dystrophic and healthy dogs were encouraged to walk as spontaneously as possible along a 20 m corridor, and timed over 5 m. Three axial accelerations were recorded close to the center of gravity, the accelerometer being placed under the sternum, using a light elastic belt tightened around the thorax (Equimetrix device Ò). Recorded data were analysed using specific gait analysis software on ten seconds-samples of steady state locomotion. Eleven dystrophic and 7 healthy adult dogs were used to validate parameters able to discriminate these two groups. The mean regularity of dorso-ventral accelerations was found to be significantly higher in healthy than in dystrophic dogs. The frequency and length of strides were considerably reduced in dystrophic dogs, as well as the total mechanical power of gait (W/kg). Interestingly, the medio-lateral component of the power was significantly increased in dystrophic animals, demonstrating a swaying component in the gait of these dogs. Longitudinal studies in puppies show that the total power of gait is early reduced at 2 months of age in dystrophic animals, whereas the increase of the medio-lateral component of the power and the decrease of regularity progressively occur with age. These results validate accelerometry as a useful tool of functional evaluation of dystrophic dogs, since it is simple, non-invasive and efficient to quantitatively discriminate them from healthy dogs. Moreover, they provide reference data on healthy and untreated dystrophic dogs at different ages, representing comparison points for dogs receiving systemic treatments.
G.P.8.12 Mannosidase I inhibition rescues the human a-sarcoglycan R77C recurrent mutation I. Richard 1; M. Bartoli 1; E. Gicquel 1; L. Barrault 1; T. Soheili 1; M. Malissen 2; B. Malissen 2; B. Udd 3; O. Danos 1 1 Genethon, Exploratory Research, Evry, France; 2 Universite´ de la Me´diterrane´e, Centre d’Immunologie de Luminy, Marseille, France; 3 VAASA Central Hospital, Neurological Department, VAASA, Finland Limb girdle muscular dystrophy type 2D (LGMD2D, OMIM600119) is a genetic progressive myopathy that is caused by mutations in the human a-sarcoglycan gene (SGCA). We introduced in mice the most prevalent LGMD2D mutation, R77C. Unexpectedly, we observed an absence of LGMD2D-like phenotype at histological or physiological level. Using a heterologous cellular model of the sarcoglycan complex formation, we showed that the R77C allele encodes a protein that fails to be delivered to its proper cellular localization in the plasma membrane, consequently to the disappearance of a positively charged residue. Subsequently, we transferred an AAV vector coding for the human R77C protein in the muscle of Sgca-null mice and were able to pharmacologically rescue the R77C protein from endoplasmic reticulum-retention using proteasome or mannosidase I inhibitors. This suggests a therapeutic approach for
doi:10.1016/j.nmd.2008.06.212
CONGENITAL MYOPATHIES I; POSTER PRESENTATIONS G.P.9.01 A mutant skeletal muscle a-actin gene, fused to enhanced green fluorescent protein (EGFP) produces a unique myopathic mouse model K.J. Nowak 1; G. Ravenscroft 1; C. Jackaman 1; E.M. Lim 1; C.A. Sewry 2; A. Potter 3; S. Squire 3; R. Fisher 3; E. Baker 4; J.J. Feng 5; S. Marston 5; V. Fabian 6; P.J. Morling 6; A.J. Bakker 7; L.M. Griffiths 6; J. Papadimitriou 8; K.E. Davies 9; N.G. Laing 1 1 University of Western Australia, Centre for Medical Research/WAIMR, Perth, Australia; 2 Robert Jones & Agnes Hunt Orthopaedic Hospital, Wolfson Centre for Inherited Neuromuscular Disease, Oswestry, United Kingdom; 3 University of Oxford MRC Functional Genetics Unit, Department of Physiology, Anatomy and Genetics, Oxford, United Kingdom; 4 King Edward Memorial Hospital, PathWest Department of Cytogenetics, Perth, Australia; 5 Imperial College, National Heart and Lung Institute, London, United Kingdom; 6 Royal Perth Hospital, Neuro-
785
loss of force. This study highlights deleterious repercussions of the association of CsA+Prednisone at immunosuppressive levels on GRMD dogs. These data are a keystone for the analysis of results in therapeutic trials. Thus, a force improvement can be interpreted with certainty as a gain of function due to the specific treatment, and not to the immunosuppressive regimen.
LGMD2D patients carrying mutations that impair a-sarcoglycan trafficking.
doi:10.1016/j.nmd.2008.06.209
G.P.8.13
G.P.8.11
Accelerometry, a new tool to assess gait quality in dystrophin-deficient dogs I. Barthe´le´my 1; E. Barrey 2; T. Voit 2; J.L. Thibaud 1; A. Uriarte 1; S. Blot 1; J.Y. Hogrel 3 1 ENVA, Laboratoire de Neurobiologie, Maisons-Alfort, France; 2 Genopole - INSERM 902, Lab. d’Etude de la Physiologie de l’Exercice, Evry, France; 3 GH Pitie´-Salpeˆtrie`re, Institut de myologie, Paris, France
Steroid treatment causes deterioration of myocardial function in the deltasarcoglycan deficient mouse model for dilated cardiomyopathy R. Bauer 1; G.A. Mac Gowan 2; A. Blain 1; K. Bushby 1; V.W. Straub 1 1 Newcastle University, Institute of Human Genetics, Newcastle upon Tyne, United Kingdom; 2 Freeman Hospital, Department of Cardiology, Newcastle upon Tyne, United Kingdom As oral corticosteroids have a beneficial effect on muscle strength in Duchenne muscular dystrophy (DMD), it has been suggested that they may also be a useful treatment in the pathologically related sarcoglycanopathies. The delta-sarcoglycan deficient mouse (Sgcd-null) is a model for both limb girdle muscular dystrophy 2F (LGMD2F) and dilated cardiomyopathy. Our assessment of in vivo cardiac function by pressure volume loops using a conductance catheter revealed a well compensated cardiomyopathy at baseline in Sgcd-null mice with decreased myocardial contractility, increased preload and decreased afterload, maintaining a high cardiac output. To study the effect of oral corticosteroids on cardiac function we treated 8 week old Sgcd-null mice with prednisolone (1.5 mg/kg/day orally) for 8 weeks. Cardiac haemodynamics surprisingly did not improve in prednisolone treated mice but instead deteriorated with evidence of ventricular stiffening. On histology after steroid treatment there was increased myocardial cell damage reflected by higher Evans blue dye uptake (sarcolemmal injury) and increased myocardial fibrosis. In summary, prednisolone led to a decompensation of cardiac haemodynamics in Sgcd-null mice and induced additional cardiac damage. On the basis of these findings, although current clinical outcomes do not indicate a similar problem in patients on long-term corticosteroids, we conclude that careful cardiac monitoring is clearly indicated. doi:10.1016/j.nmd.2008.06.210
doi:10.1016/j.nmd.2008.06.211
Dystrophin-deficient dogs, as canine replicas of DMD patients, represent the choice model to evaluate systemic therapeutic strategies. In this context, the development of a quantitative, discriminating and non-invasive method of gait quality assessment is essential. Accelerometry, a technique based on 3D recording of accelerations, is the method we have chosen to develop, because it seems to be easy to perform in dogs and a source of several quantified parameters. In this aim, dystrophic and healthy dogs were encouraged to walk as spontaneously as possible along a 20 m corridor, and timed over 5 m. Three axial accelerations were recorded close to the center of gravity, the accelerometer being placed under the sternum, using a light elastic belt tightened around the thorax (Equimetrix device Ò). Recorded data were analysed using specific gait analysis software on ten seconds-samples of steady state locomotion. Eleven dystrophic and 7 healthy adult dogs were used to validate parameters able to discriminate these two groups. The mean regularity of dorso-ventral accelerations was found to be significantly higher in healthy than in dystrophic dogs. The frequency and length of strides were considerably reduced in dystrophic dogs, as well as the total mechanical power of gait (W/kg). Interestingly, the medio-lateral component of the power was significantly increased in dystrophic animals, demonstrating a swaying component in the gait of these dogs. Longitudinal studies in puppies show that the total power of gait is early reduced at 2 months of age in dystrophic animals, whereas the increase of the medio-lateral component of the power and the decrease of regularity progressively occur with age. These results validate accelerometry as a useful tool of functional evaluation of dystrophic dogs, since it is simple, non-invasive and efficient to quantitatively discriminate them from healthy dogs. Moreover, they provide reference data on healthy and untreated dystrophic dogs at different ages, representing comparison points for dogs receiving systemic treatments.
G.P.8.12 Mannosidase I inhibition rescues the human a-sarcoglycan R77C recurrent mutation I. Richard 1; M. Bartoli 1; E. Gicquel 1; L. Barrault 1; T. Soheili 1; M. Malissen 2; B. Malissen 2; B. Udd 3; O. Danos 1 1 Genethon, Exploratory Research, Evry, France; 2 Universite´ de la Me´diterrane´e, Centre d’Immunologie de Luminy, Marseille, France; 3 VAASA Central Hospital, Neurological Department, VAASA, Finland Limb girdle muscular dystrophy type 2D (LGMD2D, OMIM600119) is a genetic progressive myopathy that is caused by mutations in the human a-sarcoglycan gene (SGCA). We introduced in mice the most prevalent LGMD2D mutation, R77C. Unexpectedly, we observed an absence of LGMD2D-like phenotype at histological or physiological level. Using a heterologous cellular model of the sarcoglycan complex formation, we showed that the R77C allele encodes a protein that fails to be delivered to its proper cellular localization in the plasma membrane, consequently to the disappearance of a positively charged residue. Subsequently, we transferred an AAV vector coding for the human R77C protein in the muscle of Sgca-null mice and were able to pharmacologically rescue the R77C protein from endoplasmic reticulum-retention using proteasome or mannosidase I inhibitors. This suggests a therapeutic approach for
doi:10.1016/j.nmd.2008.06.212
CONGENITAL MYOPATHIES I; POSTER PRESENTATIONS G.P.9.01 A mutant skeletal muscle a-actin gene, fused to enhanced green fluorescent protein (EGFP) produces a unique myopathic mouse model K.J. Nowak 1; G. Ravenscroft 1; C. Jackaman 1; E.M. Lim 1; C.A. Sewry 2; A. Potter 3; S. Squire 3; R. Fisher 3; E. Baker 4; J.J. Feng 5; S. Marston 5; V. Fabian 6; P.J. Morling 6; A.J. Bakker 7; L.M. Griffiths 6; J. Papadimitriou 8; K.E. Davies 9; N.G. Laing 1 1 University of Western Australia, Centre for Medical Research/WAIMR, Perth, Australia; 2 Robert Jones & Agnes Hunt Orthopaedic Hospital, Wolfson Centre for Inherited Neuromuscular Disease, Oswestry, United Kingdom; 3 University of Oxford MRC Functional Genetics Unit, Department of Physiology, Anatomy and Genetics, Oxford, United Kingdom; 4 King Edward Memorial Hospital, PathWest Department of Cytogenetics, Perth, Australia; 5 Imperial College, National Heart and Lung Institute, London, United Kingdom; 6 Royal Perth Hospital, Neuro-