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P50 Down-regulation of ColQ by RNA interference as a potential alternative therapy in myasthenic disorders
S18
Abstracts, UK Neuromuscular Translational Research Conference 2010 Posters / Neuromuscular Disorders 20S1 (2010) S5–S30
Methods: Cases of late recurrent thymoma were retrospectively identified and medical notes were reviewed. Results: 5 patients with a recurrent thymoma were identified. 4 were male. The average age at first tumour presentation was 47.6. 4 patients presented with MG. 4 had apparent full excision of their thymoma. One patient had invasive disease at first presentation with incomplete resection and adjuvant radiotherapy. The mean disease free interval to recurrence was 13.5 years. Three cases of recurrence were detected on routine scanning whereas the other 2 patients presented with cough or chest pain. Four patients had repeat surgery. Two patients had palliative radiotherapy and two had chemotherapy. 3 patients died. One patient was successfully treated for recurrence but developed sporadic motor neuron disease. One patient remains disease free 3 years after repeat surgery. Conclusion: Thymoma may recur many years after surgery even if the initial tumour has apparently been completely resected. Tumour recurrence may be associated with a poor prognosis. Surveillance scanning after thymoma resection is essential and should continue indefinitely. P49 Poster The use of stimulation jitter analysis with concentric needle electrodes in the diagnosis of myasthenia M. Pitt1 . 1 Great Ormond Street Hospital for Children NHS Trust, Great Ormond Street, London WC1N 3JH, UK. Objective: The diagnosis of myasthenia in children, encompassing both Autoimmune Myasthenia Gravis and the congenital myasthenic syndromes, is challenging. We analysed our 12 year experience of using Stimulation Jitter Analysis by Concentric needle Electrode (Stim JACE) in the investigation of children with neuromuscular weakness and assessed its role in the diagnosis of myasthenia and other causes of neuromuscular transmission disorder (NTD). Methods: Children who underwent Stim JACE between 1997 and 2009 were retrospectively identified from our departmental database. Medical records, pathology and genetic test results were reviewed. Sensitivity and specificity of Stim JACE were determined in the subgroup of patients with definite (genetic/antibody confirmed) and probable myasthenia (clinical diagnosis). Results: A total of 151 Stim JACE fulfilled the study’s entry criteria. The sensitivity of Stim JACE in the diagnosis of myasthenia varied from 93–97% with a specificity of 42–47%. Positive predictive value for diagnosis of myasthenia was 47–48% and negative predictive value 91–97%. In patients who had alternative diagnoses and abnormal jitter, the findings were often explained by the presence of a condition that was known to cause NTD, which could be diagnosed at the time of the examination. Other conditions previously not recognised as having NTD were also identified. Conclusions: Stim JACE is a well tolerated, valuable and reliable tool in diagnosing myasthenic syndromes and other causes of NTD in children. We recommend the use of Stim JACE as an initial screening test in all children with symptoms suggestive of myasthenia.
The aim is to investigate whether RNAi, targeting mouse Colqi mRNA, will enhance neuromuscular transmission; by causing a loss in the ColQ associated forms of AChE found specifically at the neuromuscular junction. Three sequences, located at different positions along the mRNA length, were targeted for knockdown using siRNAs and shRNAexpressing vectors. The effects were investigated in vitro using an EGFP fusion construct and later in vivo using neuromuscular junction markers. RNAi targeting mouse Colqi mRNA effectively down-regulates expression in both HEK TSA cells and at the NMJ of wild-type mice. Our future work will investigate whether the down-regulation of ColQ will be therapeutic in the AChR deficient congenital myasthenic syndrome mouse model. P51 Poster Ephedrine treatment in DOK7 CMS and investigation of potential mechanisms J. Cossins1 , D. Lashley1 , H. Spearman1 , S. Maxwell1 , J. Palace2 , S. Robb3 , D. Beeson1 . 1 Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, UK; 2 Department of Clinical Neurology, John Radcliffe Hospital, Oxford, UK; 3 Dubowitz Neuromuscular Centre, Institute of Child Health & Great Ormond Street Hospital, 30 Guilford Street London, UK Recent reports suggest that patients with Dok-7 congenital myasthenic syndrome (CMS) benefit from treatment with ephedrine. We performed a prospective follow-up study to quantify the changes in patient muscle strength and mobility in response to ephedrine. Ten patients not previously on ephedrine, began treatment under supervision of 0.5–1.0 mg/kg/day and muscle strength was measured using the quantitative myasthenia gravis (QMG) severity score and mobility scores. Patients were assessed at initiation of treatment and at follow up at two months and 6–8 months. Ephedrine produced a progressive improvement in muscle strength with the median falling from 17/39 at baseline to 10/39 by 6–8 months (p = 0.009, Wilcoxon signed-rank test). Similarly mobility scores showed a marked improvement (p = 0.0006, two tailed paired t test). The mechanism through which ephedrine exerts this therapeutic effect is unclear, but it may be through an effect on b2-adrenergic receptors that partially compensates for the loss of Dok-7 function. We generated an immortalised human skeletal muscle cell line derived from a Dok-7 CMS patient in order to investigate possible affects on the AChR clustering pathway. This cell line demonstrated reduced agrin-induced AChR clustering compared to a control human muscle cell line, indicating that endogenous mutant Dok-7 affects either AChR cluster formation or cluster stability or both. However, initial experiments do not provide clear evidence for how ephedrine compensates for the mutant Dok-7.
Peripheral Nerve Disease
P50 Poster Down-regulation of ColQ by RNA interference as a potential alternative therapy in myasthenic disorders
P52 Poster Exploring the experience of living with fatigue in people with Charcot–Marie–Tooth disease – a qualitative study
J. Kenyon1 . 1 Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK
G.M. Ramdharry1,2 , M.M. Reilly2 , J.F. Marsden3 . 1 School of Physiotherapy, St George’s University of London and Kingston University, London, UK; 2 MRC Centre for Neuromuscular Diseases, Department of Molecular Pathogenesis, University College London, London, UK; 3 School of Health Professions, University of Plymouth, Plymouth (UK)
AChE is localised and concentrated at the NMJ by the anchoring protein ColQ. It functions to end signal transmission by cleaving the neurotransmitter ACh; either before it reaches the AChR or as it dissociates. Disorders of the NMJ may be either genetic or autoimmune, and often result in a loss of signal reaching the muscle. AChE is the target for one current therapy in myasthenia. AChE inhibitors aim to increase the amount of time ACh is present at the NMJ, enhancing neuromuscular transmission.
This qualitative study explored the phenomenon of fatigue for people with Charcot–Marie–Tooth disease (CMT), while acknowledging the triggers, impact and strategies people have developed to manage this symptom in daily life.
Abstracts, UK Neuromuscular Translational Research Conference 2010 Posters / Neuromuscular Disorders 20S1 (2010) S5–S30
Methods: Cases of late recurrent thymoma were retrospectively identified and medical notes were reviewed. Results: 5 patients with a recurrent thymoma were identified. 4 were male. The average age at first tumour presentation was 47.6. 4 patients presented with MG. 4 had apparent full excision of their thymoma. One patient had invasive disease at first presentation with incomplete resection and adjuvant radiotherapy. The mean disease free interval to recurrence was 13.5 years. Three cases of recurrence were detected on routine scanning whereas the other 2 patients presented with cough or chest pain. Four patients had repeat surgery. Two patients had palliative radiotherapy and two had chemotherapy. 3 patients died. One patient was successfully treated for recurrence but developed sporadic motor neuron disease. One patient remains disease free 3 years after repeat surgery. Conclusion: Thymoma may recur many years after surgery even if the initial tumour has apparently been completely resected. Tumour recurrence may be associated with a poor prognosis. Surveillance scanning after thymoma resection is essential and should continue indefinitely. P49 Poster The use of stimulation jitter analysis with concentric needle electrodes in the diagnosis of myasthenia M. Pitt1 . 1 Great Ormond Street Hospital for Children NHS Trust, Great Ormond Street, London WC1N 3JH, UK. Objective: The diagnosis of myasthenia in children, encompassing both Autoimmune Myasthenia Gravis and the congenital myasthenic syndromes, is challenging. We analysed our 12 year experience of using Stimulation Jitter Analysis by Concentric needle Electrode (Stim JACE) in the investigation of children with neuromuscular weakness and assessed its role in the diagnosis of myasthenia and other causes of neuromuscular transmission disorder (NTD). Methods: Children who underwent Stim JACE between 1997 and 2009 were retrospectively identified from our departmental database. Medical records, pathology and genetic test results were reviewed. Sensitivity and specificity of Stim JACE were determined in the subgroup of patients with definite (genetic/antibody confirmed) and probable myasthenia (clinical diagnosis). Results: A total of 151 Stim JACE fulfilled the study’s entry criteria. The sensitivity of Stim JACE in the diagnosis of myasthenia varied from 93–97% with a specificity of 42–47%. Positive predictive value for diagnosis of myasthenia was 47–48% and negative predictive value 91–97%. In patients who had alternative diagnoses and abnormal jitter, the findings were often explained by the presence of a condition that was known to cause NTD, which could be diagnosed at the time of the examination. Other conditions previously not recognised as having NTD were also identified. Conclusions: Stim JACE is a well tolerated, valuable and reliable tool in diagnosing myasthenic syndromes and other causes of NTD in children. We recommend the use of Stim JACE as an initial screening test in all children with symptoms suggestive of myasthenia.
The aim is to investigate whether RNAi, targeting mouse Colqi mRNA, will enhance neuromuscular transmission; by causing a loss in the ColQ associated forms of AChE found specifically at the neuromuscular junction. Three sequences, located at different positions along the mRNA length, were targeted for knockdown using siRNAs and shRNAexpressing vectors. The effects were investigated in vitro using an EGFP fusion construct and later in vivo using neuromuscular junction markers. RNAi targeting mouse Colqi mRNA effectively down-regulates expression in both HEK TSA cells and at the NMJ of wild-type mice. Our future work will investigate whether the down-regulation of ColQ will be therapeutic in the AChR deficient congenital myasthenic syndrome mouse model. P51 Poster Ephedrine treatment in DOK7 CMS and investigation of potential mechanisms J. Cossins1 , D. Lashley1 , H. Spearman1 , S. Maxwell1 , J. Palace2 , S. Robb3 , D. Beeson1 . 1 Neurosciences Group, Weatherall Institute of Molecular Medicine, University of Oxford, UK; 2 Department of Clinical Neurology, John Radcliffe Hospital, Oxford, UK; 3 Dubowitz Neuromuscular Centre, Institute of Child Health & Great Ormond Street Hospital, 30 Guilford Street London, UK Recent reports suggest that patients with Dok-7 congenital myasthenic syndrome (CMS) benefit from treatment with ephedrine. We performed a prospective follow-up study to quantify the changes in patient muscle strength and mobility in response to ephedrine. Ten patients not previously on ephedrine, began treatment under supervision of 0.5–1.0 mg/kg/day and muscle strength was measured using the quantitative myasthenia gravis (QMG) severity score and mobility scores. Patients were assessed at initiation of treatment and at follow up at two months and 6–8 months. Ephedrine produced a progressive improvement in muscle strength with the median falling from 17/39 at baseline to 10/39 by 6–8 months (p = 0.009, Wilcoxon signed-rank test). Similarly mobility scores showed a marked improvement (p = 0.0006, two tailed paired t test). The mechanism through which ephedrine exerts this therapeutic effect is unclear, but it may be through an effect on b2-adrenergic receptors that partially compensates for the loss of Dok-7 function. We generated an immortalised human skeletal muscle cell line derived from a Dok-7 CMS patient in order to investigate possible affects on the AChR clustering pathway. This cell line demonstrated reduced agrin-induced AChR clustering compared to a control human muscle cell line, indicating that endogenous mutant Dok-7 affects either AChR cluster formation or cluster stability or both. However, initial experiments do not provide clear evidence for how ephedrine compensates for the mutant Dok-7.
Peripheral Nerve Disease
P50 Poster Down-regulation of ColQ by RNA interference as a potential alternative therapy in myasthenic disorders
P52 Poster Exploring the experience of living with fatigue in people with Charcot–Marie–Tooth disease – a qualitative study
J. Kenyon1 . 1 Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK
G.M. Ramdharry1,2 , M.M. Reilly2 , J.F. Marsden3 . 1 School of Physiotherapy, St George’s University of London and Kingston University, London, UK; 2 MRC Centre for Neuromuscular Diseases, Department of Molecular Pathogenesis, University College London, London, UK; 3 School of Health Professions, University of Plymouth, Plymouth (UK)
AChE is localised and concentrated at the NMJ by the anchoring protein ColQ. It functions to end signal transmission by cleaving the neurotransmitter ACh; either before it reaches the AChR or as it dissociates. Disorders of the NMJ may be either genetic or autoimmune, and often result in a loss of signal reaching the muscle. AChE is the target for one current therapy in myasthenia. AChE inhibitors aim to increase the amount of time ACh is present at the NMJ, enhancing neuromuscular transmission.
This qualitative study explored the phenomenon of fatigue for people with Charcot–Marie–Tooth disease (CMT), while acknowledging the triggers, impact and strategies people have developed to manage this symptom in daily life.