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2007 NEWS

DECEMBER

22 - Spinal stability is improved by inducing a lumbar lordosis in boys with Duchenne Muscular Dystrophy: A pilot study

19 - (Am. J. Roentgenol., Jan 2008; 190: W8 - W12)Three-Point Technique of Fat Quantification of Muscle Tissue as a Marker of Disease Progression in Duchenne Muscular Dystrophy: Preliminary Study

Tishya A. L. Wren, Stefan Bluml, Linda Tseng-Ong and Vicente Gilsanz - USA

OBJECTIVE. Clinical trials involving patients with Duchenne muscular dystrophy are hindered by the lack of suitable objective end points. The purpose of this study was to examine whether muscle lipid infiltration measured with the three-point Dixon MRI technique has value as a marker of disease severity.

SUBJECTS AND METHODS. Disease severity in nine boys (mean age, 8.6 ± 2.7 years) with Duchenne muscular dystrophy was determined with the functional ability scale of Brooke and associates. Functional scores were compared with strength measurements obtained by manual testing of muscles of the lower extremities, knee extensor strength measured with an isokinetic dynamometer, and muscle fat percentage in the quadriceps and hamstrings determined with the three-point Dixon MRI technique.

RESULTS. MRI measurements of fat infiltration had stronger correlation (p < 0.05) with functional grade than did measurements obtained with manual muscle testing (p = 0.07) or quantitative strength measured with the isokinetic dynamometer (p = 0.54). Muscle fat percentage did not correlate with strength measurements from manual or dynamometer muscle testing but increased with age in subjects with Duchenne muscular dystrophy.

CONCLUSION. Muscle adiposity values obtained with three-point Dixon MRI are accurate in assessment of disease severity in patients with Duchenne muscular dystrophy. Because they are not influenced by patient effort or examiner variability, these measurements are more objective and reproducible than measurements of muscle strength.

13 - (Chest. 132(6):1977-1986, December 2007) American College of Chest Physicians Consensus Statement on the Respiratory and Related Management of Patients With Duchenne Muscular Dystrophy Undergoing Anesthesia or Sedation

Birnkrant, David J.; Panitch, Howard B.; Benditt, Joshua O.; Boitano, Louis J. ; Carter, Edward R. MD, ; Cwik, Valerie A. ; Finder, Jonathan D. ; Iannaccone, Susan T. ; Jacobson, Lawrence E. ; Kohn, Gary L. ; Motoyama, Etsuro K. ; Moxley, Richard T. ; Schroth, Mary K. ; Sharma, Girish D. ; Sussman, Michael D. - USA

This statement on the management of patients with Duchenne muscular dystrophy (DMD) undergoing procedural sedation or general anesthesia represents the consensus opinion of a multidisciplinary panel convened under the auspices of the American College of Chest Physicians. Expert recommendations on this subject are needed for several reasons. First, patients with DMD have an increased risk of complications when they undergo sedation or general anesthesia. In addition, due to improved cardiopulmonary therapies, patients with DMD are experiencing an unprecedented duration of survival. As a result, it is more common for them to require procedures involving sedation or general anesthesia. The risks related to anesthesia and sedation for DMD patients include potentially fatal reactions to inhaled anesthetics and certain muscle relaxants, upper airway obstruction, hypoventilation, atelectasis, congestive heart failure, cardiac dysrhythmias, respiratory failure, and difficulty weaning from mechanical ventilation. This statement includes advice regarding the highly interrelated areas of respiratory, cardiac, GI, and anesthetic management of patients with DMD undergoing general anesthesia or procedural sedation. The statement is intended to aid clinicians involved in the care of patients with DMD and to be a resource for other stakeholders in this field, including patients and their families. It is an up-to-date summary of medical literature regarding this topic and identifies areas in need of future research.

13 - (Anaesthesia. 63(1):89-91, January 2008) Acute liver failure following therapeutic paracetamol administration in patients with muscular dystrophies.[Report]

Pearce, B.; Grant, I. S. - UK

Clinically significant liver damage in patients taking therapeutic doses of paracetamol is very rare. We report two cases of fulminant hepatic failure caused by therapeutic (4 g.day-1) paracetamol administration on our Intensive Care Unit. Both patients had a muscular dystrophy and presented with a chest infection on a background of endstage neuromuscular respiratory failure. We also noted one further similar case in the literature and suggest a relationship between muscular dystrophy and paracetamol-induced hepatotoxicity. In this report we discuss in detail possible mechanisms that may account for this apparent association, which include altered pharmacokinetics, reduced glutathione stores, malnutrition and hypoxic injury.
 

12 -  (Cell Stem Cell, December - 2007) Restoration of Human Dystrophin Following Transplantation of Exon-Skipping-Engineered DMD Patient Stem Cells into Dystrophic Mice

Rachid Benchaouir, Mirella Meregalli, Andrea Farini, Giuseppe D'Antona, Marzia Belicchi,Aurélie Goyenvalle, Maurizio Battistelli, Nereo Bresolin,Roberto Bottinelli,Luis Garcia, and Yvan Torrente - Italy and France

Duchenne muscular dystrophy (DMD) is a hereditary disease caused by mutations that disrupt the dystrophin mRNA reading frame. In some cases, forced exclusion (skipping) of a single exon can restore the reading frame, giving rise to a shorter, but still functional, protein. In this study, we constructed lentiviral vectors expressing antisense oligonucleotides in order to induce an efficient exon skipping and to correct the initial frameshift caused by the DMD deletion of CD133+ stem cells. The intramuscular and intra-arterial delivery of genetically corrected CD133 expressing myogenic progenitors isolated from the blood and muscle of DMD patients results in a significant recovery of muscle morphology, function, and dystrophin expression in scid/mdx mice. These data demonstrate that autologous engrafting of blood or muscle-derived CD133+ cells, previously genetically modified to reexpress a functional dystrophin, represents a promising approach for DMD.

Stem cell therapy counters muscular dystrophy in mice: study

12 - PPMD Annual Connect Conference, Philadelphia, 12 - 14 July 2007 - Günter Scheuerbrandt report

8 - Swallowing difficulties in Duchenne muscular dystrophy: Indications for feeding assessment and outcome of videofluroscopic swallow studies

NOVEMBER

24 - Duchenne muscle activity evaluation and muscle function preservation: is it possible a prophylactic strategy?

15 -  Flk-1(+) Adipose-Derived Mesenchymal Stem Cells Differentiate into Skeletal Muscle Satellite Cells and Ameliorate Muscular Dystrophy in MDX Mice

14 - Human multipotent adipose derived stem cells restore dystrophin expression of Duchenne skeletal muscle cells in vitro

14 - (47th Annual Meeting of American Society of Cell Biology, December 2007)

The Potential Influence of NF-kappaB Down Regulation on the Activity of the PI3/AkT Pathway in Dystrophic (mdx) Skeletal Muscle

B. Lee,¹ G. W. Millman,¹ E. C. Turin,¹ A. Samadi,² C. G. Carlson¹; ¹Physiology, A.T. Still University of Health Sciences, Kirksville, MO, ²Biochemistry, A.T. Still University of Health Sciences, Kirksville, MO

Recent evidence indicating that treatments to reduce the activity of the NF-kappaB pathway may be useful in treating Duchenne and Becker muscular dystrophy (Carlson et al., Neurobiology of Disease, 20 (3):719-730, 2005; Messina et al., Experimental Neurology 198:234-241, 2006; Acharyya et al., J. Clin. Invest. 117, 889-901, 2007) provides the rationale for ongoing experiments which are directed at identifying specific phenotypic endpoints for assessing drug efficacy using the mdx mouse model for Duchenne muscular dystrophy. Consideration of the central importance of the PI3kinase/Akt pathway in promoting the growth and regeneration of skeletal muscle, however, suggests that a combined treatment to reduce the activity of the NF-kappaB pathway and increase PI3kinase/Akt activation may be an appropriate therapy for this group of diseases. In order to investigate this possibility, we have begun to examine the status of the PI3kinase/Akt pathway in costal diaphragm cytosolic extracts obtained from mdx mice treated either acutely or chronically with two inhibitors of the NF-kappaB pathway, pyrrolidine dithiocarbamate (PDTC; 50 mg/kg) and sulfasalazine (SS; 100 mg/kg). Western blots of phosphorylated and total Akt indicate that a single injection of either of these two agents does not modify the activity of the PI3kinase/Akt pathway. Initial experiments suggest that daily treatment of mdx mice with PDTC for a period of at least 30 days may activate the PI3kinase/Akt pathway, but that corresponding treatment with sulfasalazine has no effect on the proportion of phosphorylated Akt. Although it is currently unclear whether chronic treatment with these established NF-kappaB inhibitors effectively down regulates nuclear NF-kappaB activation in dystrophic skeletal muscle, these preliminary results suggest that chronic treatment with NF-kappaB inhibitors that reduce IkappaB-alpha kinase activity (IKK) may be used in conjunction with PI3kinase/Akt activation to judiciously enhance muscle regeneration in dystrophic skeletal muscle.

Evaluation of the Effectiveness of a Mast Cell Degranulation Inhibitor in Dystrophic mdx Mice

D. D. Araujo,^1,2 F. S. M. Pires,² T. T. Fuzisaki,² J. C. S. Bizario,² M. R. Costa^1,2; ¹Cellular Molecular Biology, University of São Paulo, Ribeirão Preto, Brazil, ²Medicine School, University of Ribeirão Preto, Ribeirão Preto, Brazil

Duchenne muscular dystrophy (DMD) is characterized by progressive muscle degeneration which results from the absence of dystrophin. The dystrophin deficient mdx mouse, the most widely used animal model for DMD, shows milder phenotype that can be intensified by compulsory physical activity. Inflammatory response and immune cells contribute to muscle degeneration and/or regeneration. Mast cells are recruited to the injury sites and liberate mediators that increase collagen production, attract other inflammatory cells and intensify tissue damage. Olopatadine, an H1-histamine antagonist and a mast cell degranulation inhibitor, decreases Ca²⁺ influx and the liberation of histamine, tryptase, leukotrienes and prostaglandins. In this study, we evaluated the effect of 10 mg/kg/day olopatadine in male mdx mice submitted to physical activity (20 minutes of treadmill running at 20 cm/s, 3 times a week, during 5 weeks). To characterize the experimental groups (treated and untreated) before (4 week old mdx) and after (9 week old mdx) of the physical activity program, we used the following parameters: i) measurement of body weight and serum creatine kinase; ii) qualitative and quantitative histopathological analyses of gastrocnemius and diaphragm (Evans Blue Dye infiltration and H&E staining to evaluate myofibers morphology, the presence of inflammatory infiltrates, peripherally and centrally nucleated myofibers, and grouped regenerating myofibers). The results showed that the 9 week old olopatadine treated mice presented significant reduction in the CK levels and amelioration of the muscular condition. We detected significant reduction in the number of myofibers with sarcolemma injury but no difference in the number of centrally nucleated myofibers. The analysis of the individual values suggests a trend to reduction in the inflammatory infiltrate area and in the degeneration/regeneration ratio. These data suggest that the inhibition of mast cell is beneficial to retard the dystrophinopathy progress and can be considered as an option to clinical trials for DMD.

13 -  Kiwi company's medical breakthrough

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10 -  (Journal of the Neurological Sciences, 2007) Connective tissue growth factor is overexpressed in muscles of human muscular dystrophy

8 - (Prostaglandins, Leukotrienes and Essential Fatty Acids, 2007) Effects of inhibitors of the arachidonic acid cascade on primary muscle culture from a Duchenne muscular dystrophy patient

I. Gáti O., Danielsson, T. Betmark, J. Ernerudh, K. Öllinger and N. Dizdar - Sweden

The aim of this study was to elucidate the mechanisms of action for potential targets of therapeutic intervention related to the arachidonic acid cascade in muscular dystrophy. Primary cultures from a Duchenne patient were used to study the expression of dystrophin-1, utrophin, desmin, neonatal myosin heavy chain (MHCn) and Bcl-2 during inhibition of phospholipase A2 (PLA₂), cyclooxygenase (COX) and lipoxygenase (LOX). Hypo-osmotic treatment was applied in order to trigger Ca²⁺ influx and PLA₂ activity. Inhibition of PLA₂ and LOX with prednisolone and nordihydroguaiaretic acid (NDGA) caused a semi-quantitative increase of utrophin and Bcl-2-, and a dose-dependent, quantitative increase of desmin expression, an effect that was augmented by hypo-osmotic treatment. Our results indicate that LOX inhibitors, similarly to corticosteroids, can be beneficial in the treatment of muscular dystrophies

6 - (American Heart Association Annual Meeting, 2007) 1) Minor Myocardial Damage and LV Dysfunction in Patients with Duchenne Muscular Dystrophy -The Preventive Efficacy of Carvedilol on Plasma Cardiac Troponin I-

Takao Nishizawa; Fumihiko Yasuma; Motoko Sakai; Satoshi Kuru; Seigo Kimura; Rei Shibata; Taiki Ohashi; Akiko Noda; Hideo Izawa; Kohzo Nagata; Mitsuhiro Yokota; Masaaki Konagaya; Toyoaki Murohara - Japan

Background: Cardiac dysfunction is one of the major prognostic factors in patients with Duchenne muscular dystrophy (DMD). Minor myocardial damage assessed by plasma cardiac troponin I (cTnI) is often observed in patients with DMD. However, it is unclear that how the minor myocardial damage occurs to which patient with DMD and how it relates to LV dysfunction. Therefore, we assessed the hypothesis that minor myocardial damage is associated with LV dysfunction, the evaluation of plasma cTnI helps the prediction of LV functional deterioration, and carvedilol prevents elevation of plasma cTnI in patients with DMD.

Methods: Plasma cTnI were repeatedly (every 3 months) measured for 2 years and LV function was assessed by echocardiography in 58 patients with DMD. Carvedilol (2.5–5 mg/day) was orally administered for a year to the patients who have shown plasma cTnI elevation (positive cTnI, cut off 0.06ng/mL).

Results: There were 3 differential groups regarding the progression rate of LV systolic dysfunction, i.e. rapid (19% of total, LVEF < 50% in their 10^th), slow (50% of total, LVEF > 50% in their 20 –30^th), and unchanged group (31% of total, LVEF < 50% in their 20 –30^th). The episode of positive cTnI was observed in 27 (46%) of total patients with DMD. LVEF was lower in patients with positive cTnI than that with negative cTnI (42 ± 2 vs. 52 ± 2%, p < 0.05). Positive cTnI was observed in all patients in rapid group, 84% of patients in slow group, and only 6% of patients in unchanged group. Fourteen differential dystrophin gene mutations were recognized in 48 patients but they were not associated with those 3 differential groups or patients with positive cTnI. Administration of carvedilol in 13 patients (LVEF 40 ± 3) decreased the cTnI detection rate (from 44 ± 5% to 26 ± 10%, p < 0.05), while it was unchanged in 14 patients (LVEF 41 ± 3) without carvedilol treatment (from 44 ± 7% to 39 ± 6%) during same observation period.

Conclusions: The elevation of plasma cTnI was associated with LV systolic dysfunction in patients with DMD. The prediction of LV dysfunction in patients with DMD may be feasible with combinations of age, LVEF, and plasma cTnI elevation. Carvedilol could be a new therapeutic strategy to prevent minor myocardial damage in patients with DMD.

2) Prevention of Heart Failure in delta-Sarcoglycan Knock-Out Mice after Intravenous Gene Transfer with Targeted Adeno-Associated Viral (AAV) Vectors

Caroline Goehringer; Désirée Rutschow; Stefanie Schinkel; Raffi Bekeredjian; Ralf Bauer; Dieter Weichenhan; Jürgen A Kleinschmidt; Hugo A Katus; Oliver J Müller - Germany

Background: Delta-Sarcoglycan (SGCD) is a member of the dystrophin-associated glycoprotein complex. Mutations may result in isolated dilated cardiomyopathy or limb-girdle muscle dystrophy 2F with variable cardiac involvement. A potential gene therapeutic approach requires an efficient myocardial gene transfer. AAV vectors are suitable for cardiac gene transfer. Novel AAV serotypes such as AAV-8 or -9 even enable a systemic gene transfer in rodents. Aim of our study was to establish a vector for efficient systemic cardiac gene transfer and its subsequent use to prevent heart failure by expressing the SGCD cDNA in SGCD knock out mice.

Material and Methods: 10¹¹ genomic particles of AAV-8 and -9 vectors harboring a luciferase reporter gene under control of the CMV-enhanced myosin light chain promoter were intravenously injected into adult NMRI mice (n=6 and n=10, respectively). After 4 weeks, reporter activities were determined in representative organs. Analogous, 2x10¹¹ AAV-9 SGCD and AAV-9 EGFP vectors were intravenously injected in SGCD knock out mice (n=9 and n=7, respectively). Cardiac function (fraction of shortening) was assed by echocardiography at the beginning and the end of the study after 6 months. Running distances were measured using voluntary wheel running.

Results: Reporter gene transfer with AAV-9 vectors resulted in increased cardiac luciferase activities compared to AAV-8 (3.8x10⁸ ±4.4x10⁸ relative light units [RLU]/mg protein versus 0.10x10⁸ ±0.08x10⁸ RLU/mg protein, p=0.05) with increased specificity. In comparison to EGFP controls, AAV-9 delta-sarcoglycan gene transfer resulted in a significant increase in running distance and a significant decrease in decline in fraction of shortening (67.6% to 65.0% versus 69.9% to 58.1%; p=0.04). Immunohistochemical analyses in AAV-9 SGCD treated knock-out mice revealed a transmural reconstitution of more than 90% of cardiomyocytes.

Conclusion: Intravenous injections of AAV-9 SGCD vectors enable an efficient transmural cardiac gene transfer in adult mice and prevent deterioration of left ventricular function in SGCD knock out mice. Therefore, this vector system may be suitable for validation of novel targets for cardiac diseases

3) Abnormal Myocardial Circumferential Strain Precedes Global Functional Decline in Duchenne Muscular Dystrophy: A Cardiac Magnetic Resonance Tagging Study Using HARP Analysis

Kan N Hor; Larry W Markham; Janaka Wansapura; Wojciech Mazur; Linda Cripe; D. Woodrow Benson; William M Gottliebson - USA

BACKGROUND: Duchenne Muscular Dystrophy (DMD), an x-linked myopathy, is characterized by progressive cardiac dysfunction and myocardial fibrosis late in the disease process. We hypothesized that left ventricular myocardial peak circumferential strain (_cc) abnormalities would exist in DMD prior to global systolic functional abnormalities regardless of age or left ventricular ejection fraction (EF).

METHODS: We evaluated 33 DMD males undergoing clinical cardiac MRI. Comparison was made to 13 age-matched healthy volunteers. Standard imaging included short-axis cine stack, cine myocardial tagging and myocardial delayed enhancement (MDE). Cardiac functional analysis was performed using Medis MASS software. Tagged images of only the mid-LV were analyzed using HARP software. For analysis, DMD males were subdivided by age: < or > 10 years. All subjects < 10 years had normal EF (>55%); none exhibited MDE. Subjects >10 years were divided by MDE status and EF (>55% or <55%). Student’s t-test was used to test for differences between groups.

RESULTS: DMD subjects with normal EF had abnormal _cc at an early age (<10 years) compared to control subjects (p< 0.05). DMD subjects >10 years with normal EF had further decline in =_cc compared to younger DMD boys (p<0.05). There was further decline with age in =_cc in subjects with lower EF (p<0.05) without MDE. In the oldest males studied with MDE and reduced EF, _cc was even lower (figure).

CONCLUSIONS: Myocardial strain abnormalities are prevalent in the early stages of DMD existing in the setting of normal EF and progressing with advances in age. Such strain analysis may provide an early marker to guide the efficacy of preventive or gene therapy in DMD.

2 -  (Journal of Electromyography and Kinesiology, 2007) Evaluation of plantar flexion contracture contribution during the gait of children with Duchenne muscular dystrophy

Nathaly Gaudreailt, Denis Gravel and Sylvie Nadeau - Canada

Because of extensor weakness, children with Duchenne muscular dystrophy (DMD) maintain internal flexion moments at the joints of the lower extremities when they walk. We believe that at the ankle, the plantar flexion moments caused by contractures may contribute significantly to the production of the net ankle flexion moment during the gait in these children. The goal of the present study is to quantify ankle plantar flexion passive moments that may be associated with the presence of flexion contractures and to estimate their contribution to the net moment during the gait of children with DMD. Kinematic and kinetic parameters were collected during gait of eleven subjects with DMD. Ankle plantar flexion passive moments were also measured experimentally during the same session. Fourteen control children participated in the study in order to have normal reference values. The presence of ankle plantar flexion contractures in children with DMD was reflected by a rigidity coefficient obtained at a common moment of −7 Nm that was higher for these children (0.75 Nm/° vs. 0.48 Nm/°; p < 0.05). The relative passive moment contribution to the net plantar flexion moments was higher for the children with DMD at the end of the lengthening phase of the plantar flexors (25% vs. 18%; p < 0.05). We believe that the passive moments can compensate for the presence of progressive muscle weakness in the children with DMD and help these children with gait.

2 -  (Am. J. Pathol., Nov 2007; 171: 1576 - 1587) Transgenic Overexpression of ADAM12 Suppresses Muscle Regeneration and Aggravates Dystrophy in Aged mdx Mice

Louise Helskov Jørgensen, Charlotte Harken Jensen, Ulla M. Wewer and Henrik Daa SchrødeR - Denmark

 Muscular dystrophies are characterized by insufficient restoration and gradual replacement of the skeletal muscle by fat and connective tissue. ADAM12 has previously been shown to alleviate the pathology of young dystrophin-deficient mdx mice, a model for Duchenne muscular dystrophy. The observed effect of ADAM12 was suggested to be mediated via a membrane-stabilizing up-regulation of utrophin, 7B integrin, and dystroglycans. Ectopic ADAM12 expression in normal mouse skeletal muscle also improved regeneration after freeze injury, presumably by the same mechanism. Hence, it was suggested that ADAM12 could be a candidate for nonreplacement gene therapy of Duchenne muscular dystrophy. We therefore evaluated the long-term effect of ADAM12 overexpression in muscle. Surprisingly, we observed loss of skeletal muscle and accelerated fibrosis and adipogenesis in 1-year-old mdx mice transgenically overexpressing ADAM12 (ADAM12⁺/mdx mice), even though their utrophin levels were mildly elevated compared with age-matched controls. Thus, membrane stabilization was not sufficient to provide protection during prolonged disease. Consequently, we reinvestigated skeletal muscle regeneration in ADAM12 transgenic mice (ADAM12⁺) after a knife cut lesion and observed that the regeneration process was significantly impaired. ADAM12 seemed to inhibit the satellite cell response and delay myoblast differentiation. These results discourage long-term therapeutic use of ADAM12. They also point to impaired regeneration as a possible factor in development of muscular dystrophy.

OCTOBER

29 - Santhera Reports Encouraging, First Data from Phase IIa Clinical Trial with SNT-MC17 in Duchenne Muscular Dystrophy

27 - (JCB, 2007;179(2):305) Necdin mediates skeletal muscle regeneration by promoting myoblast survival and differentiation

26 - (Circulation Research, October 2007) Twenty-One-Month-Old Carrier Mice by Mosaic Dystrophin Expression or Complementary Dystrophin/Utrophin Expression

Brian Bostick ; Yongping Yue ; Chun Long ; and Dongsheng Duan - USA

A cure for dystrophin-deficient muscular dystrophy requires treating both skeletal muscle and the heart. Whereas mosaic dystrophin expression has been shown to protect skeletal muscle, controversy exists over whether mosaic expression is protective in the heart. We have shown recently that mosaic dystrophin expression prevents stress-induced heart damage in young carrier mice. Although an interesting finding, the clinical relevance remains to be established because young dystrophin-null mdx mice do not have heart disease. On the other hand, heart failure has been reported in human carriers. To resolve this mouse/human discrepancy, we evaluated the cardiac phenotype in 21-month-old mdx, carrier, and normal mice. We found dilated cardiomyopathy in old mdx mice but not in age-matched carrier mice. All anatomical parameters and physiological assay results (ECG and closed-chest Millar catheter) were within the normal range in old carrier mice. Focal myocardial inflammation was found in a small fraction of old carrier mice, but it had no major impact on heart function. Dobutamine stress revealed a near normal hemodynamic profile except for a marginal reduction in systolic pressure in old carrier mice. Immunostaining and Western blot showed dystrophin expression in 50% cardiomyocytes in old carrier mice. Interestingly, utrophin was upregulated in dystrophin-negative heart cells in carrier mice. In summary, we have provided the first clear-cut evidence that dilated cardiomyopathy in old mdx mice was prevented by mosaic dystrophin expression or complementary dystrophin/utrophin expression. Our results raise the hope for ameliorating dystrophic cardiomyopathy through partial gene and/or cell therapy.

20 -  (Chest Meeting Abstracts, Oct 2007; 132: 607c - 608)  INCIDENCE AND OUTCOMES OF CARDIOPULMONARY RESUSCITATION IN PATIENTS WITH END-STAGE DUCHENNE MUSCULAR DYSTROPHY

Garey Noritz  David J. Birnkrant  - USA

PURPOSE: Although technological cardiopulmonary therapies, such as noninvasive ventilation (NIV), have increased life span for patients (pts) with Duchenne muscular dystrophy (DMD), the disease remains fatal. Pts with end-stage DMD who forgo “do not resuscitate” directives may be partially resuscitated after near-fatal events, exposing them to the risk of brain damage. PURPOSE: To assess the frequency of attempted resuscitation among pts with DMD in our clinic who experienced cardiopulmonary arrest, and to describe their outcomes.

METHODS: Retrospective chart review.

RESULTS: Ten of our pts with DMD died during the time period 9/1/03-4/1/07. Mean age at death _/- SD: 20.7 _/- 2.7 years. Three of the 10 pts had unmeasurable vital capacities and were dependent on NIV 24 hrs/day. Mean vital capacity of the remaining 7 pts: 0.57 _/- 0.53 liters. All pts were prescribed daily NIV but 4 pts used NIV infrequently. All pts had cardiomyopathy. Four pts were in congestive heart failure. Two pts had cardiac defibrillators. After cardiopulmonary arrest, five of the 10 pts underwent resuscitation attempts. No pt was successfully resuscitated. Four of the 5 pts died immediately. One pt was partially resuscitated, experienced brain damage, and died after being taken off the ventilator by his family.

CONCLUSION: A significant proportion of our pts with end-stage DMD who experienced cardiopulmonary arrest underwent attempted resuscitation. None of the resuscitation attempts was successful. Lack of “do not resuscitate” advance directives exposed these pts to the risk of partial resuscitation and brain damage.

CLINICAL IMPLICATIONS: Pts with advanced DMD are increasingly cared for by cardiologists, pulmonologists, and intensivists, whose focus may be technologically oriented. We speculate that use of technological therapies like assisted ventilation and defibrillators among such pts may produce an unrealistically optimistic view of their prognosis, causing resistance to advance “do not resuscitate” directives, even among pts with end-stage disease. Studies are needed regarding how to reconcile palliative and technological therapies to optimize end-of-life care among pts with severe DMD.

 19 - Acceleron Pharma's ACE-031 Increases Muscle Mass In a Preclinical Model of Glucocorticoid-Induced Muscle Loss

18 - Distinctive patterns of microRNA expression in primary muscular disorders

Scientists Uncover Leads to New Treatments for Neuromuscular Diseases

18 - PTC THERAPEUTICS ANNOUNCES ADDITIONAL RESULTS FROM PHASE 2 STUDY OF PTC124 IN DUCHENNE MUSCULAR DYSTROPHY

17 -  (Neurology, October 2007) Albuterol increases lean body mass in ambulatory boys with Duchenne or Becker muscular dystrophy

C. L. Skura, E. G. Fowler, G. T. Wetzel, M. Graves, and M. J. Spencer - USA

Background: Albuterol is a beta-2 agonist that has been demonstrated to increase muscle strength in studies in animals and humans. Based on a pilot study of extended-release albuterol Repetabs in children with dystrophinopathies, the authors conducted a randomized, double-blind, placebo-controlled study with a crossover design.

Methods: Fourteen boys with Duchenne or Becker muscular dystrophy, 6 to 11 years old, completed two treatment periods (albuterol and placebo), 12 weeks each, separated by a 12-week washout period. As the albuterol Repetab formulation was no longer available, an alternate extended release albuterol was used (Volmax, 12 mg per day). Outcome measurements included 1) lean body mass, 2) fat mass, 3) isometric knee extensor and flexor moments, 4) manual muscle testing, and 5) timed functional tests.

Results: Lean body mass was significantly higher for subjects following albuterol treatment compared to placebo treatment, while fat mass was significantly lower. No differences were found in isometric knee moments or manual muscle tests. Time to run/walk 30 feet was improved following albuterol.

Conclusions: Short-term treatment with extended release albuterol may increase lean body mass, decrease fat mass, and improve functional measures in patients with dystrophinopathies. However, the significant change in strength of specific muscle groups found in the pilot study was not observed in the present study. These findings may be attributed to differences in the drug release and kinetics between Repetab and Volmax formulations as they affect the concentration of available beta-2 receptors on the muscle cell surface differently.

13 - Safety and Efficacy Study of Antisense Oligonucleotides in Duchenne Muscular Dystrophy

12 -  (European Journal of Paediatric Neurology 11 (2007) 337-40) CINRG pilot trial of oxatomide in steroid-naıve Duchenne muscular dystrophy

Gunnar M. Buyse,, Nathalie Goemans, Erik Henricson, Alejandro Jara, Marleen van den Hauwe, Robert Leshner, Julaine M. Florence, Jill E. Mayhew, Diana M. Escolar - USA

12 - (Heart, October - 2007) Life expectancy and death from cardiomyopathy amongst carriers of Duchenne and Becker muscular dystrophy in Scotland

Susan M Holloway, Douglas E Wilcox , Alison Wilcox , John C S Dean , Jonathan N Berg , David R Goudie , Martin A Denvir  and Mary E M Porteous - United Kingdom

Objectives To assess life expectancy and cardiovascular mortality in carriers of Duchenne and Becker Muscular Dystrophy.

Design Family pedigrees of individuals affected with these conditions, held by the 4 genetics centres in Scotland, were examined to identity a cohort of definite carriers. Electronic death registration data, held by the General Register Office for Scotland were used to identify death certificates of carriers who had died, to obtain age at death and cause of death. Survival and mortality data were obtained for the general population for comparison.

Patients 397 definite carriers in 202 pedigrees were identified from which 94 deaths were identified by record linkage to death certificates.

Main outcome measures Observed numbers surviving to certain ages and numbers dying of cardiac causes were compared with expected numbers calculated from general population data. Results: There were no significant differences between observed and expected numbers surviving to ages 40-90. The standardised mortality ratio for the 371 carriers alive in 1974 was 0.53 (95% confidence interval 0.32-0.82).

Conclusions Whereas female carriers may have clinical features of cardiomyopathy, this study does not suggest that this is associated with reduced life expectancy or increased risk of cardiac death. Routine cardiac surveillance of obligate carriers is therefore probably unnecessary.

12 - PTC Therapeutics Announces Pharmacokinetic and Safety Results from Phase 2 Study of PTC124 in Duchenne Muscular Dystrophy

9 -  (Paediatrics and Child Health, Volume 17, Issue 10, October 2007, Pages 419-420) Bone profile and vitamin D level in children with Duchenne muscular dystrophy (DMD)

6 -  Markers of oxidative stress and aging in Duchene muscular dystrophy patients and the possible ameliorating effect of He:Ne laser

5 - Autologous transplantation of muscle-derived CD133+ stem cells in Duchenne muscle patients

4 - Use of Weekly Alendronate to Treat Osteoporosis in Boys with Muscular Dystrophy

4 -  (NEUROSCI BIOBEHAV REV, 2007)  Duchenne muscular dystrophy: A cerebellar disorder?

SEPTEMBER

26 - A translational approach for limb vascular delivery of the micro-dystrophin gene without high volume or high pressure for treatment of Duchenne muscular dystrophy

24 - (Faseb J, 2007) Transgenic expression of a myostatin inhibitor derived from follistatin increases skeletal muscle mass and ameliorates dystrophic pathology in mdx mice

Masashi Nakatani, Yuka Takehara, Hiromu Sugino, Mitsuru Matsumoto, Osamu Hashimoto, Yoshihisa Hasegawa, Tatsuya Murakami, Akiyoshi Uezumi, Shin’ichi Takeda, Sumihare Noji, Yoshihide Sunada, and Kunihiro Tsuchida - Japan

Myostatin is a potent negative regulator of skeletal muscle growth. Therefore, myostatin inhibition offers a novel therapeutic strategy for muscular dystrophy by restoring skeletal muscle mass and suppressing the progression of muscle degeneration. The known myostatin inhibitors include myostatin propeptide, follistatin, follistatin-related proteins, and myostatin antibodies. Although follistatin shows potent myostatin-inhibiting activities, it also acts as an efficient inhibitor of activins. Because activins are involved in multiple functions in various organs, their blockade by follistatin would affect multiple tissues other than skeletal muscles. In the present study, we report the characterization of a myostatin inhibitor derived from follistatin, which does not affect activin signaling. The dissociation constants (K_d) of follistatin to activin and myostatin are 1.72 nM and 12.3 nM, respectively. By contrast, the dissociation constants (K_d) of a follistatin-derived myostatin inhibitor, designated FS I-I, to activin and myostatin are 64.3 µM and 46.8 nM, respectively. Transgenic mice expressing FS I-I, under the control of a skeletal muscle-specific promoter showed increased skeletal muscle mass and strength. Hyperplasia and hypertrophy were both observed. We crossed FS I-I transgenic mice with mdx mice, a model for Duchenne muscular dystrophy. Notably, the skeletal muscles in the mdx/FS I-I mice showed enlargement and reduced cell infiltration. Muscle strength is also recovered in the mdx/FS I-I mice. These results indicate that myostatin blockade by FS I-I has a therapeutic potential for muscular dystrophy

23 -  (2007 Annual Meeting of  The American Society of Human Genetics) Antisense-mediated exon 51 skipping restores local dystrophin expression in muscle of Duchenne muscular dystrophy patients.

A. Aartsma-Rus¹, J.J.G.M. Verschuuren², A.A.M. Janson³, G. Platenburg³, G-J.B. van Ommen¹, J.C.T. van Deutekom^1,3 1) Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands; 2) Department of Neurology, Leiden University Medical Center, Leiden, the Netherlands; 3) Prosensa B.V. Leiden, the Netherlands.

   Antisense-mediated reading frame restoration is currently one of the most promising therapeutic approaches for Duchenne muscular dystrophy (DMD). In this approach, antisense oligoribonucleotides (AONs) induce specific exon skipping during pre-mRNA splicing. They have been successful in repairing the disrupted open reading frame accompanied by the generation of internally deleted, partially functional Becker-like dystrophins. Proof of concept has been achieved in cultured muscle cells from patients, as well as in the mdx mouse model. As an essential step towards broad clinical studies and future applications, we here evaluated the effect of a single, intramuscular dose of DMD AON PRO051. Four DMD patients with different mutations were included on basis of eligible mutation, adequate condition of the target muscle, and positive in vitro PRO051 skip-response. A dose of 0.8 mg PRO051, without any excipient, was injected locally into tibialis anterior muscle and a biopsy was taken after 4 weeks. Exon 51 skipping on RNA level and restoration of dystrophin expression was confirmed for each patient, as demonstrated by RT-PCR, immunohistochemical and western blot analyses. Dystrophin levels were ~10% of wild type levels, except for one patient who suffered from a severe loss of muscle fibers and profound signs of dystrophy in his tibialis muscle . The AON was well tolerated and did not provoke serious adverse events in any of the patients. Our results provide a strong basis for subsequent studies on systemic treatment of DMD patients.
 

21 -  Safety and Efficacy of Carvedilol Therapy for Patients with Dilated Cardiomyopathy Secondary to Muscular Dystrophy

21 - Genetic treatments in muscular dystrophies

19 - 18 years experience with mechanical ventilation in patients with Duchenne muscular dystrophy

19 - The silent yet successful revolution of mechanical ventilation in patients with neuromuscular disorders, in particular Duchenne muscular dystrophy

16 - (The 2nd Congress of Asian Society for Pediatric Research - 2007)

15 - (Spine, 32(20), 2007, 2278-2283) Tranexamic Acid Diminishes Intraoperative Blood Loss and Transfusion in Spinal Fusions for Duchenne Muscular Dystrophy Scoliosis

Shapiro, Frederic ; Zurakowski, David P; Sethna, Navil F - USA

Study Design. Retrospective review of intraoperative blood loss and blood replacement.

Objective. We compared intraoperative blood loss and blood replacement during spinal fusion surgery for scoliosis in Duchenne muscular dystrophy (DMD) performed with and without the synthetic antifibrinolytic agent tranexamic acid (TXA).

Summary of Background Data. High levels of intraoperative blood loss are widely documented in DMD patients undergoing posterior spinal fusion for scoliosis. The effect of the antifibrinolytic agent tranexamic acid on decreasing the blood loss has not been studied in a large group of DMD patients.

Methods. All 56 DMD patients underwent posterior spinal fusion with the same technique using 2 rods and multiple sublaminar wires. TXA was not used in 36 patients and was used in 20. In the respective groups, the age at surgery (14 vs. 13.9 years), the preoperative deformity (45° vs. 51°), the mean number of levels fused (14.3 vs. 14.7), and the mean surgical times (446 minutes vs. 459 minutes) were similar. TXA dose was 100 mg/kg in solution over 15 minutes before incision followed by an infusion of 10 mg/kg per hour during surgery. Standardized measurements of intraoperative blood loss were used and calculated to compare total amount of blood loss in milliliters per patient and blood loss as a percentage in relation to estimated blood volume [estimated blood loss (EBL)/estimated blood volume (EBV) × 100]. The EBV was calculated to be 70 mL/kg (body weight).

Results. Mean blood loss with TXA was 1944 ± 789 mL (range, 760–4000 mL) and without TXA was 3382 ± 1795 mL (range, 600–9580 mL) (P < 0.001). Blood loss with TXA decreased by 42% compared with those not treated with TXA. Accounting for patient weight and estimated blood volume, mean % blood loss with and without TXA was 47% ± 28% versus 112% ± 67% (P < 0.001). This physiologic indicator shows that blood loss with TXA decreased by 58% compared with those patients not treated with TXA. TXA was also found to reduce blood loss after accounting for surgical time. No hypercoagulation or other complications from TXA therapy were obs-erved. The reduced blood loss in TXA-treated patients translated into decreased blood transfusions. Transfusion of homologous whole blood and packed red blood cells in the TXA group was decreased by 46% compared with the no TXA group (mean levels, 512 ± 470 mL vs. 955 ± 718 mL), and transfusion of autologous cell saver blood was decreased by 42% in the TXA group (mean levels, 419 ± 235 mL vs. 728 ± 416 mL).

Conclusion. TXA significantly reduces both intraoperative blood loss and the need for homologous transfusion of whole blood and packed red blood cells in DMD patients undergoing posterior spinal fusion for scoliosis.

15 - CTS-IPITA-IXA 2007 Joint Conference – Abstracts - Minneapolis – September 15–20, 2007

13 - 6th Monaco Round Table report, held on June 23rd, 2007

12 - Dystrophin levels as low as 30% are sufficient to avoid muscular dystrophy in the human

11 -  (Am J Physiol Heart Circ Physiol 293: H1969-H1977, 2007) The role of reactive oxygen species in the hearts of dystrophin-deficient mdx mice

Iwan A. Williams and David G. Allen - Australia

Duchenne muscular dystrophy (DMD) is caused by deficiency of the cytoskeletal protein dystrophin. Oxidative stress is thought to contribute to the skeletal muscle damage in DMD; however, little is known about the role of oxidative damage in the pathogenesis of the heart failure that occurs in DMD patients. The dystrophin-deficient (mdx) mouse is an animal model of DMD that also lacks dystrophin. The current study investigates the role of the antioxidant N-acetylcysteine (NAC) on mdx cardiomyocyte function, Ca²⁺ handling, and the cardiac inflammatory response. Treated mice received 1% NAC in their drinking water for 6 wk. NAC had no effect on wild-type (WT) mice. Immunohistochemistry experiments revealed that mdx mice had increased dihydroethidine (DHE) staining, an indicator of superoxide production; NAC-treatment reduced DHE staining in mdx hearts. NAC treatment attenuated abnormalities in mdx cardiomyocyte Ca²⁺ handling. Mdx cardiomyocytes had decreased fractional shortening and decreased Ca²⁺ sensitivity; NAC treatment returned mdx fractional shortening to WT values but did not affect the Ca²⁺ sensitivity. Immunohistochemistry experiments revealed that mdx hearts had increased levels of collagen type III and the macrophage-specific protein, CD68; NAC-treatment returned collagen type III and CD68 expression close to WT values. Finally, mdx hearts had increased NADPH oxidase activity, suggesting it could be a possible source of increased reactive oxygen species in mdx mice. This study is the first to demonstrate that oxidative damage may be involved in the pathogenesis of the heart failure that occurs in mdx mice. Therapies designed to reduce oxidative damage might be beneficial to DMD patients with heart failure.

11 - (Arch Neurol. 2007;64:1236-1241) Gene Therapy for Duchenne Muscular Dystrophy: Expectations and Challenges

Louise R. Rodino-Klapac; Louis G. Chicoine; Brian K. Kaspar; Jerry R. Mendell  - USA
 

Duchenne muscular dystrophy is a debilitating X-linked disease with limited treatment options. We examined the possibility of moving forward with gene therapy, an approach that demonstrates promise for treating Duchennemuscular dystrophy. Gene therapy is not limited to replacement of defective genes but also includes strategies using surrogate genes with alternative but effective means of improving cellular function or repairing gene mutations. The first viral-mediated gene transfer for any muscle disease was carried out at Columbus Children's Research Institute and Ohio State University for limb girdlemuscular dystrophy type 2D, and the first viral-mediated trial of gene transfer for Duchenne muscular dystrophy is under way at the same institutions. These studies, consisting of intramuscular injection of virus into a single muscle, are limited in scope and represent phase 1 clinical trials with safety as the primary end point. These initial clinical studies lay the foundation for future studies, providing important information about dosing, immunogenicity, and viral serotype in humans. This article highlights the challenges and potential pitfalls as the field advances this treatment modality to clinical reality.

10 - Abstracts of Researchs that will be presented on 12th International Meeting of World Muscle Society, Italy, October, 17- 20 - 2007

9 - Enhanced Na+/H+ Exchange Activity Contributes to the Pathogenesis of Muscular Dystrophy via Involvement of P2 Receptors

9 - Modulation of Insulin-like Growth Factor (IGF)-I and IGF-Binding Protein Interactions Enhances Skeletal Muscle Regeneration and Ameliorates the Dystrophic Pathology in mdx Mice

5 - Comparative Analysis of Antisense Oligonucleotide Sequences for Targeted Skipping of Exon 51 During Dystrophin Pre-mRNA Splicing in Human Muscle

1 - Autologous Transplantation of SM/C-2.6(+) Satellite Cells Transduced with Micro-dystrophin CS1 cDNA by Lentiviral Vector into mdx Mice

1 - (American Journal of Transplantation, 2007, 7(10)- 2247-59) A Synthetic Mechano Growth Factor E Peptide Enhances Myogenic Precursor Cell Transplantation Success

Myogenic precursor cell (MPC) transplantation is a good strategy to introduce dystrophin expression in muscles of Duchenne muscular dystrophy (DMD) patients. Insulin-like growth factor (IGF-1) promotes MPC activities, such as survival, proliferation, migration and differentiation, which could enhance the success of their transplantation. Alternative splicing of the IGF-1 mRNA produces different muscle isoforms. The mechano growth factor (MGF) is an isoform, especially expressed after a mechanical stress. A 24 amino acids peptide corresponding to the C-terminal part of the MGF E domain (MGF-Ct24E peptide) was synthesized. This peptide had been shown to enhance the proliferation and delay the terminal differentiation of C₂C₁₂ myoblasts. The present study showed that the MGF-Ct24E peptide improved human MPC transplantation by modulating their proliferation and differentiation. Indeed, intramuscular or systemic delivery of this synthetic peptide significantly promoted engraftment of human MPCs in mice. In vitro experiments demonstrated that the MGF-Ct24E peptide enhanced MPC proliferation by a different mechanism than the binding to the IGF-1 receptor. Moreover, MGF-Ct24E peptide delayed human MPC differentiation while having no outcome on survival. Those combined effects are probably responsible for the enhanced transplantation success. Thus, the MGF-Ct24E peptide is an interesting agent to increase MPC transplantation success in DMD patients.

AUGUST

29 - Primary Role of Functional Ischemia, Quantitative Evidence for the Two-Hit Mechanism, and Phosphodiesterase-5 Inhibitor Therapy in Mouse Muscular Dystrophy

28 - Quadrupling Muscle Mass in Mice by Targeting TGF-ß Signaling Pathways

28 - (Neuromuscular Disorders, 2007) Workshop report: Behavior patterns in Duchenne muscular dystrophy: Report on the Parent Project Muscular Dystrophy behavior workshop 8–9 of December 2006, Philadelphia, USA LIBRARY

James Poysky - USA

Introduction

Eighteen participants representing clinicians, scientists, parents, industry, and public health agencies involved in the assessment and treatment of children with Duchenne muscular dystrophy (DMD) from Australia, Canada, the Netherlands, the UK and the USA met in Philadelphia on December 8–9, 2006 to attend a workshop addressing behavioral issues among children and young adults with DMD. The workshop, sponsored by Parent Project Muscular Dystrophy (PPMD–USA), was organized in response to parent and clinician concerns regarding behavior associated with DMD, and its subsequent impact on patient and family quality of life. For the purposes of clarification, in this report the term “behavior” is defined as readily observable external actions and responses, as well as internal affective/emotional states. The aims of the workshop were to (1) evaluate current findings and determine whether characteristic behaviors occur among boys and young men with DMD, (2) examine etiological factors contributing to behavior patterns in DMD, and (3) develop recommendations for research and intervention strategies.

DMD is a genetic disorder occurring in approximately one in 3300 live male births. Mutations in the dystrophin gene result in an absence of dystrophin or a non-functional dystrophin protein. The different types and locations of the mutation are highly variable across individuals, and it is unclear to what extent this has an impact on the phenotype. However, in all cases progressive muscle degeneration ensues, with morbidity typically occurring in the second or third decade of life. Muscle degeneration has understandably been the primary focus of research and treatment, and much less emphasis has been placed on behavioral functioning. There is, however, emerging evidence of central nervous system (CNS) involvement resulting in cognitive and neurobehavioral disorders. In addition, because of the debilitating and fatal nature of the disorder, significant psychosocial factors must also be considered. Behavioral functioning has a significant impact on quality of life and can also directly affect medical care, in particular as it is related to things like treatment adherence and behavioral response to medication. Research to date is limited, and studies have typically focused on one component of physiological, cognitive, or emotional functioning in DMD. The complex interactions between these various factors have not been clearly defined. As such, greater understanding of these interactions is necessary for appropriate patient care and treatment planning.

25 -  (Neuromuscular Disorders, 2007) Case report: Myoglobinuria in boys with Duchenne muscular dystrophy on corticosteroid therapy

Myoglobinuria is a recognised complication of Duchenne muscular dystrophy (DMD), but has only once been reported in ambulant boys on corticosteroid therapy [Dubowitz V, Kinali M, Main M, Mercuri E, Muntoni F. Remission of clinical signs in early Duchenne muscular dystrophy on intermittent low-dosage prednisolone therapy. Eur J Paediatr Neurol 2002;6(3):153–9.]. We present three prednisolone-treated boys with myoglobinuria and in two cases this was recurrent. All three showed improved motor performance in response to the introduction of corticosteroids. The greater activity of steroid-treated individuals may place their dystrophin-deficient muscles under greater mechanical stress, predisposing to further muscle fibre damage and consequent myoglobinuria. Families and physicians need to have an increased awareness of this possibility and of the appropriate management of myoglobinuria.

25 - Investigation of Poor Academic Achievement in Children with Duchenne Muscular Dystrophy

25 - Videofluorographic assessment of swallowing function in patients with Duchenne muscular dystrophy

25 - Review Article: Mechanical ventilation in Duchenne patients with chronic respiratory insufficiency: clinical implications of 20 years published experience

25 - Utrophin up-regulation by an artificial transcription factor in transgenic mice

22 - (Pediatric Anesthesia,2007) Duchenne muscular dystrophy: an old anesthesia problem revisited  LIBRARY

Jason Hayes, Francis Veyckemans, Bruno Bissonnette - Canada e Belgium

13 - (Brain & Development 29:596-500,2007) Cardiac troponin I for accurate evaluation of cardiac status in myopathic patients

11- 2007 Annual Conference Powerpoint Presentations

2 - T and B lymphocyte depletion has a marked effect on the fibrosis of dystrophic skeletal muscles in the scid/mdx mouse

JULY

31 -  (Growth Hormone & IGF Research, 2007) Muscular dystrophy-related quantitative and chemical changes in adenohypophysis GH-cells in golden retrievers

A.R. de Lima , J.R. Nyengaard , A.A.L. Jorge , J.C.C. Balieiro , C. Peixoto , E.T. Fioretto , C.E. Ambrosio f, M.A. Miglino , M. Zatz , A.A.C.M. Ribeiro - Brazil

31 -  (International Journal of Cardiology,2007) Letter to the Editor: Holter electrocardiogram should be systematic in Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is due to mutations in the dystrophin gene on chromosome Xp21.1. Dystrophin is a sarcolemmal protein which binds actin to extra cellular matrix. A deficiency in dystrophin leads to breakdown of muscle membrane and muscular alteration [1]. The disease is clinically characterized by proximal weakness and wasting, leading to loss of ambulation by 12 years of age. The heart is affected to various degrees, depending on the stage of the disease. The most common cardiac abnormality in DMD is dilated cardiomyopathy. Conduction system disease and tachyarrhythmias may occur in some patients. Death occurs in early adulthood secondary to respiratory or cardiac failure [2], even if recent advances in the use of inspiratory and expiratory muscle aids have greatly reduced the risk of pulmonary morbidity and mortality rates [3].The typical initial manifestation of cardiac involvement in DMD is sinus tachycardia [1]. Cardiac involvement is due to progressive replacement of the cardiomyocytes and the Purkinje system by connective tissue or fat [1]. Impairment of cardiac autonomic function in patients with DMD is well known. Kirchmann found sinus tachycardia in 26% and reduced heart rate variability in 51% [4]. In human cardiac purkinje fibers, immunocytochemical staining showed that dystrophin was localised to the membrane surface of the purkinjer fiber [5]. The cardiac rhythm abnormalities play a significant role in morbidity and mortality in this disease [6]. Supraventricular ectopy or couplets are reported to indicate increasing severity of arrhythmia with the progression of disease [7]. 33% of DMD patients had ventricular premature beats in a study including 45 Duchenne muscular dystrophy patients without congestive heart failure and followed up for 3 years [8]. Patients who died suddenly were more likely to have had documented complex ventricular arrhythmias (6 of 9; 66%) [8].Shortened PQ interval and prolonged QT interval are also reported. In a controlled series including 328 DMD patients, 62% had conduction abnormalities like shortened PQ interval and prolonged QT interval by age 10 years [9]. Conduction system disease was also reported. Indeed, complete atrioventricular block was reported in the literature in 1997 [10]. Holter electrocardiogram should be systematic periodically in the following of the DMD patients because of possible occurring conduction system disease and tachyarrhythmias. According to American paediatrics recommendations, periodic Holter monitoring should be considered for patients with demonstrated cardiac dysfunction [2].

[6] Corrado G, Lissoni A, Beretta S, et al. Prognostic value of electrocardiograms, ventricular late potentials, ventricular arrhythmias, and left ventricular systolic dysfunction in patients with Duchenne muscular dystrophy. Am J Cardiol 2002;89:838–41.

[7] Yanagisawa A, Miyagawa M, Yotsukura M, et al. The prevalence and prognostic significance of arrhythmias in Duchenne muscular dystrophy. Am Heart J 1992;124:1244–50

                    Mechanism of action of ACE inhibitors and Angiotensin II blockers

27 -  Episodic hypoxia exacerbates respiratory muscle dysfunction in DMD(mdx) mice

25 - Workshop report: 145th ENMC International Workshop: Planning for an International Trial of Steroid Dosage Regimes in DMD (FOR DMD)  22–24th October 2006, Naarden, The Netherlands

25 - Arrhythmia follow-up of children and adolescents with neuromuscular diseases

24 -  (American Heart Journal, 2007) Perindopril preventive treatment on mortality in Duchenne muscular dystrophy: 10 years' follow-up

Denis Duboc; Christophe Meune, Bertrand Pierre, Karim Wahbi, Bruno Eymard, Annick Toutain, Carole Berard, Guy Vaksmann, Simon Weber, Henry-Marc Becane - France

Background: Duchenne muscular dystrophy (DMD), an X-linked disorder due to lack of dystrophin, is associated with muscle weakness and myocardial dysfunction. Although preliminary data support the efficacy of angiotensin-converting enzyme inhibitors on left ventricular (LV) function, our aim was to examine the long-term impact of a preventive treatment with perindopril on mortality in children with DMD.

Methods: Patients with DMD between the ages of 9.5 and 13 years presenting with normal LV ejection fraction were included in this prospective study. They were randomly assigned for 3 years to perindopril, 2 to 4 mg (group 1), or placebo (group 2) in a double-blind protocol, followed by open-label treatment with perindopril for up to 10 years. Survival rate at 10 years in each group is reported.

Results: There were 28 patients assigned to group 1 and 29 to group 2. Baseline characteristics were similar in both groups. At the end of the 10 years' follow-up period, survival status was available for all included patients: 26 (92.9%) of 28 patients in group 1 were alive at 10 years versus 19 (65.5%) of 29 in group 2 (P = .02). Kaplan-Meier cumulative survival was significantly lower in group 2 than in group 1 (P = .013).

Conclusion: Early initiation of treatment with perindopril is associated with a lower mortality in patients with DMD with normal LV ejection fraction at study entry.

14 - Corticotrophin releasing factor 2 receptor agonist treatment significantly slows disease progression in mdx mice

14 - Low bone mineral density and decreased bone turnover in Duchenne muscular dystrophy

12 - New Target For Muscular Dystrophy Drug Therapy Found

ERF Silences Extrasynaptic Utrophin by N-Box-mediated Repression in Skeletal Muscle

7 - Antisense-induced exon skipping for duplications in Duchenne muscular dystrophy

7 - Quantification of muscle strength and motor ability in patients with Duchenne muscular dystrophy on steroid therapy

3 - Antisense oligonucleotide induced exon skipping and the dystrophin gene transcript: cocktails and chemistries

2 - (Journal of Endocrinology (2007) 194, 63-76) Alterations in myostatin expression are associated with changes in cardiac left ventricular mass but not ejection fraction in the mouse

Jorge N Artaza, Suzanne Reisz-Porszasz, Joan S Dow, Robert A Kloner, James Tsao  Shalender Bhasin  and Nestor F Gonzalez-Cadavid - USA

Myostatin (Mst) is a negative regulator of skeletal muscle in humans and animals. It is moderately expressed in the heart of sheep and cattle, increasing considerably after infarction. Genetic blockade of Mst expression increases cardiomyocyte growth. We determined whether Mst overexpression in the heart of transgenic mice reduces left ventricular size and function, and inhibits in vitro cardiomyocyte proliferation. Young transgenic mice overexpressing Mst in the heart (Mst transgenic mice (TG) under a muscle creatine kinase (MCK) promoter active in cardiac and skeletal muscle, and Mst knockout (Mst (–/–)) mice were used. Xiscan angiography revealed that the left ventricular ejection fraction did not differ between the Mst TG and the Mst (–/–) mice, when compared with their respective wild-type strains, despite the decrease in whole heart and left ventricular size in Mst TG mice, and their increase in Mst (–/–) animals. The expected changes in cardiac Mst were measured by RT-PCR and western blot. Mst and its receptor (ActRIIb) were detected by RT-PCR in rat H9c2 cardiomyocytes. Transfection of H9c2 with plasmids expressing Mst under muscle-specific creatine kinase promoter, or cytomegalovirus promoter, enhanced p21 and reduced cdk2 expression, when assessed by western blot. A decrease in cell number occurred by incubation with recombinant Mst (formazan assay), without affecting apoptosis or cardiomyocyte size. Anti-Mst antibody increased cardiomyocyte replication, whereas transfection with the Mst-expressing plasmids inhibited it. In conclusion, Mst does not affect cardiac systolic function in mice overexpressing or lacking the active protein, but it reduces cardiac mass and cardiomyocyte proliferation.

JUNE

30 - New Genetic Test Developed At Emory Advances Detection And Diagnosis Of Muscular Dystrophy

23 - Myocardial Strain Imaging for Early Detection of Cardiac Involvement in Patients with Duchenne's Progressive Muscular Dystrophy

22 - Injection of a recombinant AAV serotype 2 into canine skeletal muscles evokes strong immune responses against transgene products

21 -  Morpholino Oligomer-Mediated Exon Skipping Averts the Onset of Dystrophic Pathology in the mdx Mouse

18 -  (Biology of Blood and Marrow Transplantation, 2007) Hematopoietic Cell Transplantation Directly into Dystrophic Muscle Fails to Reconstitute Satellite Cells and Myofibers

16 -  VEGF overexpression via adeno-associated virus gene transfer promotes skeletal muscle regeneration and enhances muscle function in mdx mice

16 -  The role of reactive oxygen species in the hearts of dystrophin-deficient (mdx) mice

16 - Language disturbances in a group of participants suffering from Duchenne muscular dystrophy: a pilot study

16 - Chronic respiratory failure in patients with neuromuscular diseases: diagnosis and treatment LIBRARY

9 - Potential of oligonucleotide-mediated exon-skipping therapy for Duchenne muscular dystrophy

8 - Living with muscular dystrophy: health related quality of life consequences for children and adults

7 -  (Free Radical Biology and Medicine; 43(1):145-54) Low intensity training decreases markers of oxidative stress in skeletal muscle of mdx mice

Jan J. Kaczor, , Julie E. Hall, Eric Payne and Mark A. Tarnopolsky - Canada

Reactive oxygen species may contribute to the pathogenesis of muscular dystrophy. High intensity exercise clearly induces muscle damage in mdx mice; however, the effects of low intensity exercise training (LIT) on mdx muscle are less clear. We examined the effect of LIT on markers of oxidative stress (malondialdehyde and protein carbonyls), antioxidant (superoxide dismutase, catalase, and glutathione peroxidase), and mitochondrial (2-oxoglutarate dehydrogenase and cytochrome oxidase) enzymes in skeletal muscle of mdx and wild-type mice. Mdx and wild-type mice were allocated to LIT and sedentary groups. Malondialdehyde levels were higher in white muscle from sedentary mdx as compared to both sedentary and LIT wild-type mice (P < 0.001). Protein carbonyl content was higher in white and red muscle of mdx versus wild-type mice (P < 0.05). LIT was associated with lower levels of malondialdehyde and protein carbonyls in white muscle of mdx mice (decreased 38 and 44%, P < 0.001 and P < 0.01, respectively). Antioxidant and mitochondrial enzyme activities were higher in white muscle of mdx than in wild-type mice (P < 0.05). LIT in mdx mice induced physiological adaptation resulting in lower levels of markers of oxidative stress that were not different than those from wild type. These results are of relevance for therapeutic exercise in patients with dystrophinopathy where exercise prescription remains controversial.

7 -  Herpes Simplex Virus VP22 Enhances Adenovirus-Mediated Microdystrophin Gene Transfer to Skeletal Muscles in Dystrophin-Deficient (mdx) Mice

5 - Effects of a CRF2R agonist and exercise on mdx and wildtype skeletal muscle

2 - The role of corticosteroids in muscular dystrophy: A critical appraisal

MAY

25 - Passive in vivo elastography from skeletal muscle noise

23 - (Am J Physiol Regul Integr Comp Physiol, 2007 ) Reversal by relaxin of altered ileal spontaneous contractions in dystrophic (mdx) mice through a nitric oxide-mediated mechanism

Maria Caterina Baccari, Silvia Nistri, Maria Giuliana Vannucchi, Franco Calamai, and Daniele Bani - Italy

Altered nitric oxide (NO) production/release is involved in gastrointestinal motor disorders occurring in dystrophic (mdx) mice. Since the hormone relaxin (RLX) can up-regulate NO biosynthesis, its effects on spontaneous motility and NO synthase (NOS) expression in the ileum of dystrophic (mdx) mice were investigated. Mechanical responses of ileal preparations were recorded in vitro via force-displacement transducers. Evaluation of the expression of NOS isoforms was performed by immunohistochemistry and Western blot. Normal and mdx mice were distributed into three groups: untreated, RLX-pretreated, vehicle-pretreated. Ileal preparations from the untreated animals showed spontaneous muscular contractions whose amplitude was significantly higher in mdx than in normal mice. Addition of RLX, alone or together with L-arginine, to the bath medium depressed the amplitude of the contractions in the mdx mice, thus re-establishing a motility pattern typical of the normal mice. The NOS inhibitor L-NNA or the guanylate cyclase inhibitor ODQ reversed the effects of RLX. In RLX-pretreated mdx mice, the amplitude of spontaneous motility was reduced, thus resembling that of the normal mice, and NOS II expression in the muscle coat was increased in respect to the vehicle-pretreated mdx animals. These results indicate that RLX can reverse the altered ileal motility of mdx mice to a normal pattern, likely by up-regulating NOS II expression and NO biosynthesis in the ileal smooth muscle.

22 - Multipotential mesoangioblast stem cell therapy in the mdx/utrn(-/-) mouse model for Duchenne muscular dystrophy

18 - (Acta Histochemica, 2007) Fibre-related nitric oxide synthase (NOS) in Duchenne muscular dystrophy

16 - Red-green color vision impairment in duchenne muscular dystrophy

15 -  Localized Treatment with a Novel FDA-Approved Proteasome Inhibitor Blocks the Degradation of Dystrophin and Dystrophin-Associated Proteins in mdx Mice

12 - .Mice Adipose Derived Flk-1(+) Mesenchymal Stem Cells Can Ameliorate Duchenne's Musclular Dystrophy in Mdx Mice for Their Multilineage Potential

12 -  (Invest Ophthalmol Vis Sci 2007;48: E-Abstract 5277) Extraocular Muscles Buffer Calcium Better Than Limb Muscle: Implications for Preferential Sparing in Duchenne's Muscular Dystrophy

U. Zeiger, M. H. J. Wiesen, C. H. Mitchell and T. S. Khurana - USA

Abstract

Purpose:Duchenne's Muscular Dystrophy (DMD) is the most common fatal, genetic disease in males and associated with widespread muscle wasting. Extraocular muscles (EOMs) are spared in DMD, although the reasons for this preferential sparing remain elusive. Dysregulation of calcium homeostasis has been suggested to contribute to muscle damage in DMD. Based on morphological observations, pharmacological tests and expression profiling, we propose that EOM sparing is facilitated by differential calcium buffering properties of EOM compared to limb (tibialis anterior-TA) muscle. We investigated the role of candidate proteins as well as compared calcium handling properties of cultured myotubes from EOM and TA.

Methods:The sarcoplasmic reticulum (SR) content of EOM and TA muscle was calculated from electron microscopy (EM) micrographs. Quantitative PCR was used to compare mRNA expression levels. Primary myoblasts from EOM and TA from 5-10-day old Sprague Dawley rats were cultured and fused in vitro, using the Rando & Blau (1994) protocol. Intracellular calcium buffering was determined using Fura-2 loaded myotubes after challenging the cells with ionomycin and 300nM extracellular Ca²⁺.

Results:EM morphometry showed a 1.7 fold larger SR area in pale global EOM fibers than TA. The expression of mRNAs for several calcium and SR related proteins including SERCA1, Phospholamban and S100a1 was higher in EOM than TA. Cultured EOM myotubes showed 2.3 fold larger calcium peaks in response to sudden increases in calcium. However, the signal decayed 1.7 fold faster in EOM than in TA, implying a more efficient buffering from excessive calcium levels in these muscles.

Conclusions:Larger SR and differential expression of calcium buffering proteins may contribute to the improved ability of EOM to handle elevated intracellular calcium levels. This in turn would be predicted to protect EOM from the calcium-mediated damage noted in DMD limb muscles.

12 -  (Invest Ophthalmol Vis Sci 2007;48: E-Abstract 3772) Upregulation of Retinal Dystrophin Dp260 Transcription by Methylprednisolone is Mediated by Glucocorticoid Receptor

D.-A. M. Pillers, B. Malmin, J. T. den Dunnen, D. R. Trune and J. Pang -  USA and The Netherland

Abstract

Purpose:The Duchenne muscular dystrophy (DMD) gene encodes several isoforms of dystrophin via either internal or external promoters. Internal promoters are located within introns, and their regulatory mechanisms are not well described. Dp260, also known as retinal dystrophin, is a 260kDa isoform of dystrophin that is expressed in the outer-plexiform layer of the retina and is associated with normal retinal electrophysiology. We sought to characterize the Dp260 internal promoter within DMD intron 29 and to identify elements that regulate its expression.

Methods:The human Dp260 promoter region was cloned, sequenced, and analysed for potential regulatory elements. A luciferase reporter-promoter construct was transfected into cell lines and exposed to methylprednisolone and the glucocorticoid receptor (GR) antagonist RU486. Transcriptional activity was measured. Potential transcription factors were characterized by EMSA.

Results:Two glucocorticoid response elements were identified by sequence analysis. Transcription was upregulated in Y79 (retinoblastoma), C2 (myoblast), and HeLa cells, but not in the GR-deficient COS-7 cell line. Transcription was blocked by RU486. EMSA showed a shift in the presence of a GRE DNA sequence and a supershift with anti-GRbeta.

Conclusions:The transcription of Dp260 can be manipulated by the use of steroid drugs and the effect is mediated by the glucocorticoid receptor binding to glucocorticoid response elements. This is of particular interest in the light of current steroid clinical treatment trials for DMD. An ability to manipulate Dp260 expression by pharmacogenetic means may have implications for the treatment of DMD and inherited disorders of night vision.

9 -  (Neuromuscular Disorders, 2007) Managing Duchenne muscular dystrophy – The additive effect of spinal surgery and home nocturnal ventilation in improving survival

Michelle Eagle, John Bourke, Robert Bullock, Mike Gibson, Volker Straub and Kate Bushby - United Kingdom

Abstract

Objectives: To determine the long term survival in patients with Duchenne muscular dystrophy (DMD) following spinal surgery and nocturnal ventilation.

Study design: A retrospective review of 100 consecutive patients born between 1970 and 1990 was conducted.

Results: Forty-seven patients had surgical spinal fusion, 27 were subsequently ventilated. Fourteen patients received ventilation only. Thirty-nine patients received neither intervention. The age at which ventilation was required correlated with the age at which ambulation was lost. Those who walked for longer were less likely to require spinal surgery. Mean vital capacity dropped from 1.4 to 1.13 L 1 year post-operatively. Patients having both spinal surgery and ventilation had a median survival of 30 years whereas those who were only ventilated survived to 22.2 years.

Conclusion: Nocturnal ventilation improves survival in DMD. Spinal surgery does not increase forced vital capacity but in combination with nocturnal ventilation further improves median survival to 30 years.

7 -  (Neurology, 2007.68(19):1607-13) Orthopedic outcomes of long-term daily corticosteroid treatment in Duchenne muscular dystrophy

King, W M. ; Ruttencutter, R ; Nagaraja, H N. ; Matkovic, V ; Landoll, J ; Hoyle, C ; Mendell, J R. ; Kissel, J T. -  USA

Objective: To document the effects of long-term daily corticosteroid treatment on a variety of orthopedic outcomes in boys with Duchenne muscular dystrophy.

Methods: We reviewed the charts of 159 boys with genetically confirmed dystrophinopathies followed at the Ohio State University Muscular Dystrophy Clinic between 2000 and 2003. Charts were reviewed for ambulation status, type and duration of steroid treatment (if any), and orthopedic complications including presence and location of long bone fractures, vertebral compression fractures, and the presence and degree of scoliosis.

Results: The cohort consisted of 143 boys (16 boys with Becker dystrophy were excluded); 75 had been treated with steroids for at least 1 year, whereas 68 boys had never been treated or had received only a brief submaximal dose. The mean duration of daily steroid treatment was 8.04 years. Treated boys ambulated independently 3.3 years longer than the untreated group (p < 0.0001) and had a lower prevalence of scoliosis than the untreated group (31 vs 91%; p < 0.0001). The average scoliotic curve was also milder in the treated group (11.6°) compared with the untreated group (33.2°; p < 0.0001). Vertebral compression fractures occurred in 32% of the treated group, whereas no vertebral fractures were discovered in the steroid naive group (p = 0.0012). Long bone fractures were 2.6 times greater in steroid-treated patients.

Conclusions: Although boys with Duchenne muscular dystrophy on long-term corticosteroid treatment have a significantly decreased risk of scoliosis and an extension of more than 3 years' independent ambulation, they are at increased risk of vertebral and lower limb fractures compared with untreated boys.

7 - CureDuchenne Funds Dr. Giulio Cossu’s Adult Stem Cell Study

5 - Respiration and Muscular Dystrophy -  6 new researchs

2 - Gene Therapy in Muscular Dystrophy - 39 new unpublished researchs

1 - (Nature Medicine, 2007) SIK1 is a class II HDAC kinase that promotes survival of skeletal myocytes

Rebecca Berdeaux, Naomi Goebel, Laura Banaszynski, Hiroshi Takemori, Thomas Wandless, G Diane Shelton & Marc Montminy - USA

During physical exercise, increases in motor neuron activity stimulate the expression of muscle-specific genes through the myocyte enhancer factor 2 (MEF2) family of transcription factors. Elevations in intracellular calcium increase MEF2 activity via the phosphorylation-dependent inactivation of class II histone deacetylases (HDACs). In studies to determine the role of the cAMP responsive element binding protein (CREB) in skeletal muscle, we found that mice expressing a dominant-negative CREB transgene (M-ACREB mice) exhibited a dystrophic phenotype along with reduced MEF2 activity. Class II HDAC phosphorylation was decreased in M-ACREB myofibers due to a reduction in amounts of Snf1lk (encoding salt inducible kinase, SIK1), a CREB target gene that functions as a class II HDAC kinase. Inhibiting class II HDAC activity either by viral expression of Snf1lk or by the administration of a small molecule antagonist improved the dystrophic phenotype in M-ACREB mice, pointing to an important role for the SIK1-HDAC pathway in regulating muscle function.

Inhibiting class II HDAC activity by the administration of a small molecule antagonist = trichostatin A

APRIL

28 - PAPERS THAT WILL BE PRESENTED IN 59TH ANNUAL MEETING OF AMERICAN ACADEMY OF NEUROLOGY, BOSTON, 2007

28 -  (Bone, 2007) EFFECTS OF BISPHOSPHONATES ON BONE MASS AND THE INCIDENCE OF FRACTURES IN STEROID-TREATED PATIENTS WITH DUCHENNE MUSCULAR DYSTROPHY.

28 - Effect of specific respiratory muscle training in mdx mouse on calcium homeostasis and mitochondrial respiration

28 -  (Science in Sports & Exercise. 39(5):816-820, May 2007) Creatine Monohydrate Increases Bone Mineral Density in Young Sprague-Dawley Rats.

ANTOLIC, ANAMARIA ; ROY, BRIAN D. ; TARNOPOLSKY, MARK A. ; ZERNICKE, RONALD F. ; WOHL, GREGORY R. ; SHAUGHNESSY, STEPHEN G. ; BOURGEOIS, JACQUELINE M. - Canada

Introduction: Creatine kinase, found in osteoblasts, is an enzyme that is upregulated in response to interventions that enhance bone mass accretion. Creatine monohydrate supplementation can increase fat-free mass in young healthy men and women and can reduce markers of bone breakdown in boys with Duchenne muscular dystrophy.
Purpose: The objective of this study was to determine the influence of supplementation with creatine monohydrate on bone structure and function in growing rats, to establish a therapeutic model.
Materials and Methods: Creatine monohydrate (2% w.w.) (CR; N = 16) or standard rat chow (CON; N = 16) was fed to Sprague-Dawley rats beginning at 5 wk of age, for 8 wk. Bone mineral density (BMD) and content (BMC) were assessed using dual-energy x-ray absorptiometry at the beginning and end of the protocol. The rats were sacrificed, and one femur was removed for the determination of mechanical properties.
Results: The CR-treated rats showed greater lumbar BMD and femoral bending load at failure compared with the CON rats (P < 0.05).
Conclusions: Together, these data suggest that creatine monohydrate potentially has a beneficial influence on bone function and structure; further investigation is warranted into its effect on bone functional properties and its effects in disorders associated with bone loss.

24 - (European Journal of Paediatric Neurology, 2007) CINRG pilot trial of oxatomide in steroid-naıve Duchenne muscular dystrophy

23 - (NATURE, 2007) PTC124 targets genetic disorders caused by nonsense mutations

21 - Rehabilitation interventions for foot drop in neuromuscular disease

20 - (FASEB, 21, 2007) Activation of PPAR stimulates utrophin A expression in skeletal muscle cells

Pedro Miura, Joe V. Chakkalakal, John Lunde, Amanda Shaver, Guy Belanger and Bernard J. Jasmin - Canada

A potential therapeutic strategy to treat Duchenne Muscular Dystrophy (DMD) involves upregulation of utrophin in muscle fibers of patients. Our recent studies demonstrated that utrophin A is regulated by mechanisms that also promote expression of the slow myofiber program (PNAS 100: 7791–6, 2003; Hum Mol Genet. 13: 379–88, 2004). Since activation of PPAR in muscle causes a fiber type shift towards the slower, more oxidative phenotype, we initiated studies to determine whether PPAR activation also increases utrophin expression. Treatment of C2C12 muscle cells with GW501516, a PPAR agonist, caused a 50–100% increase in utrophin A mRNA levels. Examination of the human utrophin A promoter region revealed the presence of a conserved PPAR response element (PPRE). GW501516 treatment of C2C12 cells transfected with a utrophin A promoter-reporter construct induced a 50–100% increase in reporter activity. This effect was abrogated by deletion of the PPRE. Treatment of utrophin A promoter reporter transgenic mice with GW501516 also stimulated utrophin A promoter activity. In mdx mice, PPAR was found to be higher in edl and soleus muscles compared to wild type control mice. Based on these results, activation of PPAR, which promotes utrophin A expression, appears as a promising therapeutic intervention to counteract the devastating effects of DMD.

20 - (FASEB, 21, 2007) The membrane sealant poloxamer reduces membrane permeability in tibialis anterior muscles from dystrophic mdx mice

James G Ryall, Chris van der Poel, Jonathan D Schertzer, David R Plant and Gordon S Lynch - Australia

Duchenne muscular dystrophy is characterised by the loss of the membrane stabilizing protein dystrophin, resulting in an increased susceptibility to sarcolemmal injury. The membrane sealant Poloxamer 188 (P-188) prevents sarcolemmal tearing in cardiac myocytes from dystrophic mdx mice. We tested the hypothesis that P-188 would similarly reduce membrane tearing in skeletal muscles of mdx mice. Mdx and wild type mice were injected with Evans blue dye (EBD) an indicator of membrane permeability, then anesthetized for P-188 (460mg/kg) or vehicle (200µL saline) infusion via the right jugular vein. The susceptibility of the tibialis anterior (TA) muscle to contraction-induced injury (CI) was determined in situ and then prepared for histological quantification of EBD. TA muscles from mdx mice were more susceptible to CI than wild type mice, regardless of treatment. P-188 decreased the proportion of EBD positive fibers by 53% in both uninjured and injured TA muscles from mdx mice (P<0.05). These findings indicate that while P-188 does not alter the susceptibility to CI, it may play a role in maintaining sarcolemmal integrity in muscle fibers of mdx mice.

20 - (FASEB, 21, 2007)  IGF-I improves excitation-contraction coupling in skeletal muscle fibers of dystrophic mdx mice

Chris van der Poel, Jonathan D Schertzer, Thea Shavlakadze, Miranda D Grounds and Gordon S Lynch - Australia

The absence of dystrophin in Duchenne muscular dystrophy (DMD) causes progressive muscle wasting and possibly aberrant intracellular signaling including abnormal excitation-contraction coupling (ECC) in skeletal muscle. Insulin-like growth factor-I (IGF-I) is a potential therapy for DMD, and can alter ECC. We tested the hypothesis that muscle specific over-expression of IGF-I could ameliorate disruptions in ECC in muscle fibers from transgenic mdx (IGF-mdx) mice. Mechanically-skinned single fibers were prepared from the EDL muscles of mdx, IGF-mdx, and wild type mice. The number of depolarization-induced contractions (DICR) before a 50% reduction in amplitude was lower in mdx fibres (7 ± 1, n=15 fibers) than control (16 ± 2, n=12, P<0.05). There was no difference in SR Ca²⁺ properties. Rundown of DICR was improved significantly in IGF-mdx (14 ± 2, n=14) compared with mdx mice (7 ± 1, n=15, P<0.05). SR Ca²⁺ release was 300% higher in IGF-I-mdx mice, possibly due to a decrease in SR Ca²⁺ leak rate [mdx, 19.0 ± 3.5% of loaded SR (n=13) vs. IGF-mdx, 7.2 ± 3.0% (n=14)]. These results demonstrate that muscle specific over-expression of IGF-I in mdx mice can attenuate abnormal E-C coupling.

20 - (FASEB, 21, 2007) Roles of AML1 in Duchenne muscular dystrophy and in myogenesis

Rongye Shi and Yi-Wen Chen - USA

AML1 (acute myelogenous leukemia 1) was originally cloned from the breakpoint of chromosome 21 in t(8;21)(q22;q22), and is one of the most frequent targets of leukemia-associated gene aberrations. AML1 is a transcription regulator of a number of haematopoietic genes. The function of AML1 in skeletal muscle is not clear. Based on expression profiling data of muscles of non-symptomatic DMD patients (10m infants), symptomatic patients (5–12yr), and mdx mice, we hypothesized that AML1 may play an important role in the successful remodeling of muscles in DMD infants and mdx mice. To study the potential function of AML1 in muscle, we transfected C2C12 cells with an expression vector carrying AML1, and showed that the transgene facilitated myotube formation, while the transgene did not affect cell proliferation rate. Fusion index was significantly higher in AML1 transfected cells compared to insertless-vector transfected controls (P<0.0001). By expression profiling C2C12 cells transfected with AMLl, we further identified up-regulation of genes involved in myogenesis. The findings suggested that AML1 might be directly regulating genes involved in myogenesis and participating in compensatory responses in Duchenne muscular dystrophy.

20 - (FASEB, 21, 2007) Disruption of IGF-I/IGFBP interactions decreases contraction-induced injury in dystrophic skeletal muscle

Gordon S Lynch, Stefan M Gehrig, Jonathan D Schertzer and James G Ryall - Australia

Duchenne muscular dystrophy (DMD) is caused by a lack of dystrophin, a structural protein thought to confer stability to skeletal muscle fibers. A lack of dystrophin results in an increased susceptibility to contraction-induced (CI) injury. Insulin-like growth factor-I (IGF-I) therapy has beneficial effects on muscle function in mdx mice, a model of DMD. The actions of IGF-I are strongly modified by IGF binding proteins (IGFBPs). The IGF-I aptamer, NBI-31772, displaces IGFBPs from their interaction with IGF-I, releasing free biologically active IGF-I. We tested the hypothesis that disruption of IGF-I/IGFBP interactions using NBI-31772 would reduce the dystrophic pathology in mdx mice. NBI-31772 was administered to mdx mice (continuous infusion; ~6 mg/kg/day) for 4 weeks via mini osmotic pump. Muscle contractile properties were examined in vitro. NBI-31772 treatment reduced the susceptibility of the EDL and diaphragm muscles to CI injury, concomitant with reduced fatigue resistance and lower citrate synthase activity. The findings indicate that displacing IGF-I from its binding proteins can protect dystrophic muscles from CI injury.

20 - (FASEB, 21, 2007) Local expression of IGF-1 accelerates muscle regeneration by rapidly modulating inflammatory cytokines and chemokines

Laura Pelosi, Cristina Giacinti, Chiara Nardis, Giovanna Borsellino, Emanuele Rizzuto, Carmine Nicoletti, Francesca Wannenes, Luca Battistini, Nadia Rosenthal, Mario Molinaro, and Antonio Musarò - Italy

Muscle regeneration following injury is characterized by myonecrosis accompanied by local inflammation, activation of satellite cells, and repair of injured fibers. The resolution of the inflammatory response is necessary to proceed toward muscle repair, since persistence of inflammation often renders the damaged muscle incapable of sustaining efficient muscle regeneration. Here, we show that local expression of a muscle-restricted insulin-like growth factor (IGF)-1 (mIGF-1) transgene accelerates the regenerative process of injured skeletal muscle, modulating the inflammatory response, and limiting fibrosis. At the molecular level, mIGF-1 expression significantly down-regulated proinflammatory cytokines, such as tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta, and modulated the expression of CC chemokines involved in the recruitment of monocytes/macrophages. Analysis of the underlying molecular mechanisms revealed that mIGF-1 expression modulated key players of inflammatory response, such as macrophage migration inhibitory factor (MIF), high mobility group protein-1 (HMGB1), and transcription NF-B. The rapid restoration of injured mIGF-1 transgenic muscle was also associated with connective tissue remodeling and a rapid recovery of functional properties. By modulating the inflammatory response and reducing fibrosis, supplemental mIGF-1 creates a qualitatively different environment for sustaining more efficient muscle regeneration and repair.

20 - (FASEB, 21, 2007) Physical activity and muscle adaptations in dystrophic mice treated with prednisone

Jason B Nikas and Dawn A Lowe

Glucocorticoid administration is standard treatment for individuals with Duchenne’s Muscular Dystrophy. However, the drug effects on physical activity and skeletal muscle are not clearly established. We tested the hypothesis that mdx mice treated with prednisone (Pred) would be more active and that hindlimb muscles would have better contractility and greater injury-resistance compared with control mdx mice (Con). 6 wk male mdx mice were implanted with time-release prednisolone pellets, 1.5 – 2.2 mg/kg/d (n=15), or placebo pellets (n=8). Cage activity was monitored from 1 wk pre- to 8 wk post-implantation. At wk 8, mice were sacrificed, muscles harvested and EDL muscles assessed for contractility and susceptibility to eccentric contraction-induced injury. Daily cage activity, in terms of jumping and total locomotive energies, were 191 and 112% greater in Pred compared with Con mice (P0.027). The 8 wk-change in body mass was greater in Con than Pred mice (P=0.018). Masses of hindlimb extensor muscles (EDL and tibialis anterior) were lower in Pred than Con mice (P0.002). EDL specific force was 26% greater (P=0.010) in Pred (12.5 ± 0.6 N/cm²) vs Con mice (9.9 ± 0.9 N/cm²) but susceptibility to an acute injury was not affected by prednisone treatment (P0.068). Overall, these data indicate that mdx muscle responds to glucocorticoid treatment in a positive fashion but perhaps indirectly by affecting physical activity.

20 - (FASEB, 21, 2007) A calpain inhibitor fails to rescue dystrophic skeletal muscle

Joshua Taylor Selsby, Zuozhen Tian, Klara Pendrak, Jennifer Ellmer, Monica Zadel, Pedro Acosta, Elisabeth Barton and H. Lee Sweeney

Duchenne muscular dystrophy (DMD) is a fatal muscle disease caused by the absence of a functional dystrophin protein and is modeled by the mdx mouse. Numerous studies have reported an elevated calcium influx potentially leading to increased calpain activity and fiber necrosis. Efforts to target calpain with leupeptin (Leu), a calpain inhibitor, and Leu-based agents have been met with mixed results in the mdx mouse. In an effort to help clarify the ability or inability of calpain to alter disease progression, 12 mdx and 12 C57 mice were divided into four groups, including: mdx Leu, mdx PBS, C57 Leu, and C57 PBS. Animals were injected daily with Leu (36 mg/kg) or PBS i.p. for 6 mo beginning at 2 mo of age and ending at 8 mo of age. Leupeptin administration failed to improve serum creatine kinase activity or diaphragmatic specific tension. Further, muscle mass was unchanged in hind limb skeletal muscles. Lastly, histology revealed either no or minor improvements in fibrosis between PBS and leu treated animals. In summary, this evidence suggests that 36 mg/kg of Leu administration does not change muscle mass, histology, function or serum CK calling into question the validity of calpain as a long-term therapeutic target for the treatment of Duchenne muscular dystrophy. We are analyzing adaptive changes in the muscle to elucidate possible reasons for lack of a therapeutic effect.

20 - (FASEB, 21, 2007)  Chemical sympathectomy ameliorates the dystrophic pathology of limb and diaphragm muscles in mdx mice

Xilong Li, Jianfeng Ye and Gail D Thomas - USA

Mutations of the dystrophin gene cause Duchenne muscular dystrophy, but the pathogenetic mechanisms are poorly understood. We previously showed that vasoconstriction evoked by activation of sympathetic nerves or vascular -adrenoceptors is enhanced in dystrophin-deficient muscles during exercise. We therefore hypothesized that sympathetically-mediated muscle ischemia might contribute to the dystrophic phenotype. To test this, we treated C57BL10 and mdx mice with vehicle (V) or 6-hydroxydopamine (6-OHDA; 250 mg/kg, sc, on postnatal day 4, 6, 8, 10, 12) to selectively destroy peripheral sympathetic nerves. Hindlimb and diaphragm muscles were removed from 10–12 wk old mice and evaluated for dystrophic pathology. In C57BL10 mice, 6-OHDA had no effect on muscle histopathology. In mdx mice, 6-OHDA significantly reduced the number of fibers with centralized nuclei by 15% in gastrocnemius and by 25% in diaphragm (P<0.05 vs V). 6-OHDA also significantly reduced collagen infiltration by 61% in gastrocnemius and by 33% in diaphragm (P<0.05 vs V). Findings were similar in mdx mice treated with prazosin (10 mg/kg/d, po, starting at 4 wk) to block ₁-adrenoceptors. These data demonstrate that the dystrophic phenotype of hindlimb and diaphragm muscles of mdx mice is amenable to treatment with sympatholytics, suggesting a role for sympathetic nerves in the pathogenesis of muscular dystrophy.

20 - (FASEB, 21, 2007) Gene expression profiling in the early phases of DMD: a constant molecular signature characterizes DMD muscle from early postnatal life throughout disease progression

Mario Pescatori, Aldobrando Broccolini, Carlo Minetti, Enrico Bertini, Claudio Bruno, Adele D’amico, Camilla Bernardini, Massimiliano Mirabella, Gabriella Silvestri, Vincenzo Giglio, Anna Modoni, Marina Pedemonte, Giorgio Tasca, Giuliana Galluzzi, Eugenio Mercuri, Pietro A. Tonali and Enzo Ricci - Italy

Genome-wide gene expression profiling of skeletal muscle from Duchenne muscular dystrophy (DMD) patients has been used to describe muscle tissue alterations in DMD children older than 5 years. By studying the expression profile of 19 patients younger than 2 years, we describe with high resolution the gene expression signature that characterizes DMD muscle during the initial or "presymptomatic" phase of the disease. We show that in the first 2 years of the disease, DMD muscle is already set to express a distinctive gene expression pattern considerably different from the one expressed by normal, age-matched muscle. This "dystrophic" molecular signature is characterized by a coordinate induction of genes involved in the inflammatory response, extracellular matrix (ECM) remodeling and muscle regeneration, and the reduced transcription of those involved in energy metabolism. Despite the lower degree of muscle dysfunction experienced, our younger patients showed abnormal expression of most of the genes reported as differentially expressed in more advanced stages of the disease. By analyzing our patients as a time series, we provide evidence that some genes, including members of three pathways involved in morphogenetic signaling—Wnt, Notch, and BMP—are progressively induced or repressed in the natural history of DMD.

20 - (FASEB, 21, 2007) The brain-derived neurotrophic factor (BDNF) regulates skeletal muscle regeneration and is mis-regulated in dystrophic muscle

Charlene Grace Clow, Kambiz Mousavi, Robin J. Parks and Bernard J. Jasmin - Canada

Our recent studies have shown that BDNF is highly expressed in skeletal muscle satellite cells (J. Neurosci., 26: 5739, 2006). Additionally, BDNF depletion by siRNA results in precocious differentiation of myoblasts. In order to determine whether BDNF plays similar roles in vivo, we designed several complementary experiments. First, we examined mouse muscle induced to degenerate/regenerate following cardiotoxin injection. We show that BDNF expression is significantly increased during early phases of regeneration but that its expression decreases (to control levels) within 5 days post-injection. Moreover, BDNF down-regulation coincides with increased expression of several markers of differentiation. Constitutive in vivo expression of siRNAs to knockdown BDNF in regenerating muscles results in enhanced differentiation as demonstrated by the pattern of myosin heavy chain isoforms expressed. Given the therapeutic importance of regeneration for treating various muscle diseases, we also examined the expression profile of BDNF in dystrophic muscles from mdx mice. In comparison to muscles from wildtype animals, mdx mouse muscles consistently display greater levels of BDNF. Finally, genetic inactivation of BDNF in developing skeletal muscle using Cre-lox technology will also allow us to determine the impact of BDNF expression during embryonic and neonatal muscle development.

20 - Myocardial Delayed Enhancement by Magnetic Resonance Imaging in Patients With Muscular Dystrophy

Marly Conceição Silva,  Zilda Maria Alves Meira, MD, Juliana Gurgel Giannetti, Marcelo Moreira da Silva, Alysson Félix Oliveira Campos, Márcia de Melo Barbosa, Geraldo Moll Starling Filho, Rogério de Aguiar Ferreira, Mayana Zatz,  and Carlos Eduardo Rochitte - Brazil

Objectives: This study sought to analyze whether cardiovascular magnetic resonance (CMR) can detect and quantify myocardial damage in the early stages of cardiomyopathy in muscular dystrophies (MD).

Background: Muscular dystrophy is a genetic disease that involves skeletal and cardiac tissues of humans. Cardiomyopathy is common, and death secondary to cardiac or respiratory diseases occurs early in life. Cardiovascular magnetic resonance is a reliable method for assessing global and regional cardiac function, allowing also for the detection of myocardial fibrosis (MF).

Methods: Ten patients with Duchenne or Becker dystrophies were studied by CMR. Physical examination, Chagas disease serological tests, electrocardiogram, chest radiograph, total creatine kinase, and Doppler echocardiogram were also obtained in all patients.

Results: Patients with MF had a lower ejection fraction than those without. Myocardial fibrosis (midwall and/or subepicardial) was observed in 7 of the 10 patients, and the lateral wall was the most commonly involved segment. There was moderate correlation between segmental MF and dysfunction.

Conclusions: Cardiovascular magnetic resonance can identify MF and may be useful for detecting the early stages of cardiomyopathy in MD. Future work will be needed to evaluate whether CMR can influence cardiomyopathy and outcomes.

19 - (FASEB, 21, 2007) Reactive oxygen species promote sarcolemmal damage following ischemia and reperfusion of dystrophin-deficient muscles

Jianfeng Ye, Xilong Li and Gail D Thomas - USA

Mutations of the dystrophin gene cause Duchenne muscular dystrophy, but the pathogenetic mechanisms are poorly understood. We previously reported that dystrophin-deficient muscles are susceptible to ischemia during exercise. Reactive oxygen species (ROS) produced during reperfusion of ischemic muscle can cause tissue injury. Because dystrophin-deficient muscle is abnormally sensitive to ROS, we hypothesized that ischemia-reperfusion (I/R) injury would be enhanced in dystrophin-deficient muscles of mdx mice, and that this damage would be ameliorated by antioxidant treatment. Anesthetized mdx and C57BL10 mice were subjected to 1 h of unilateral hindlimb ischemia followed by 2 h of reperfusion. Sarcolemmal damage following I/R was enhanced in mdx vs C57BL10 mice as shown by greater increases in serum creatine kinase (+2775±260 vs +1136±211 U/L; P<0.05) and in Evans blue dye (EBD) uptake by muscle (EBD⁺ area: 31±6 vs 8±3% of plantaris; 27±5 vs 3±1% of soleus; P<0.05). Infusion of the superoxide dismutase mimetic tempol (172 mg/kg, iv) attenuated EBD uptake by 63% in plantaris and by 31% in soleus muscles (P<0.05 vs I/R alone) of mdx mice, but had no effect in C57BL10 mice. These data demonstrate that the hindlimb muscles of mdx mice are abnormally susceptible to I/R-induced injury, and suggest that ROS production is a key event mediating sarcolemmal damage in dystrophin-deficient muscle.

19 - Systemic Administration of Micro-dystrophin Restores Cardiac Geometry and Prevents Dobutamine-induced Cardiac Pump Failure

18 - (Biochemical and Biophysical Research Communications, 2007) Efficient conversion of ES cells into myogenic lineage using the gene-inducible system

Shiro Ozasa, Shigemi Kimura, Kaori Ito, Hiroe Ueno, Makoto Ikezawa, Makoto Matsukura, Kowashi Yoshioka, Kimi Araki, Ken-ich Yamamura, Kuniya Abe, Hitoshi Niwa and Teruhisa Miike - Japan

We established genetically engineered ES (ZHTc6-MyoD) cells that harbor a tetracycline-regulated expression vector encoding myogenic transcriptional factor MyoD, for the therapy of muscle diseases, especially Duchenne muscular dystrophy (DMD). Almost all the ZHTc6-MyoD cells were induced into muscle lineage after removal of tetracycline. The undifferentiated ZHTc6-MyoD cells are Sca-1+ and c-kit+, but CD34−, all well-known markers for mouse hematopoietic stem cells. In addition, they are able to maintain themselves in the undifferentiated state, even after one month of culture. Therefore, it is possible to obtain a large quantity of ZHTc6-MyoD cells in the undifferentiated state that maintain the potential to differentiate only into muscle lineage. Additionally, at two weeks post-injection of these cells into muscle of mdx, a model mouse of DMD, clusters of dystrophin-positive myofibers were observed at the injection site. Therefore, ES cells have considerable therapeutic potential for treating muscle diseases.

13 - Evaluation of narrative abilities in patients suffering from Duchenne Muscular Dystrophy

13 - Two novel missense mutations in the myostatin gene identified in Japanese patients with Duchenne muscular dystrophy

13 - Sustained AAV-mediated Dystrophin Expression in a Canine Model of Duchenne Muscular Dystrophy with a Brief Course of Immunosuppression

4 -  (J Appl Physiol 102: 1677–1686, 2007) The role of free radicals in the pathophysiology of muscular dystrophy

MARCH

31 - Switching genes to overdrive improves muscular dystrophy symptoms in mice

PGC-1{alpha} regulates the neuromuscular junction program and ameliorates Duchenne muscular dystrophy

27 - (American College of Cardiology Meeting 2007) Cardiac Myolysis And LV Dysfunction In Patients With Duchenne Muscular Dystrophy -Inhibitory Effect Of Carvedilol On Cardiac Myolysis

Takao Nishizawa, Fumihiko Yasuma, Akiko Noda, Hideo Izawa, Kohzo Nagata,Mitsuhiro Yokota, Toyoaki Murohara - Japan

Background: Cardiac myolysis is observed in idiopathic dilated cardiomyopathy (DCM) and elevation of a biochemical marker leads to poor prognosis. Patients with Duchenne muscular dystrophy (DMD) often have cardiomyopathy. However it is unclear that how cardiac myolysis occurs in patients with DMD and how it relates to cardiac function.

Methods: Fifty-eight Duchenne muscular dystrophy patients were subjected of this study. Serum CPK and plasma cardiac troponin I (cTnI) were repeatedly (every 3 months) measured for 2 years and LV function was assessed by echocardiography.

Results: Patients with positive cTnI (Cut off 0.06ng/mL) showed lower LVEF(42± 2%) than those of negative cTnI (52± 2%). However, 28% of the impaired LV function (LVEF<50%) never showed positive cTnI. The frequency of detecting positive cTnI was decreased according to age and decreased serum CPK level. Some patients in less than 20 years old showed positive cTnI with preserved LV function. On the other hand, patients with preserved LV function in more than 20 years old never showed positive cTnI. Administration in carvedilol (2.5-5 mg/day) in 12 patients with positive cTnI for 6 months decreased the frequency of positive cTnI (From 100% to 25%).

Conclusions: Plasma cTnI was associated with impaired LV function. Positive plasma cTnI precedes the impaired cardiac function and the frequency of detecting plasma cTnI decreased with decreased LVEF suggesting that persistent myolysis become intermittent as progression of LV dysfunction. Repeated measurements of plasma cTnI may be useful to predict development of LV dysfunction. Carvedilol administration is one of the effective therapies to prevent cardiac myolysis.

26 - (J. Clin. Pharmacol,2007; 47:430-444) Safety, Tolerability, and Pharmacokinetics of PTC124, a Nonaminoglycoside Nonsense Mutation Suppressor, Following Single- and Multiple-Dose Administration to Healthy Male and Female Adult Volunteers

Samit Hirawat, Ellen M. Welch, Gary L. Elfring, Valerie J. Northcutt, Sergey Paushkin, MD,  Seongwoo Hwang,  Eileen M. Leonard,  Neil G. Almstead,  William Ju, MD, Stuart W. Peltz, and Langdon L. Miller - USA

Nonsense (premature stop codon) mutations are causative in 5% to 15% of patients with monogenetic inherited disorders. PTC124, a 284-Dalton 1,2,4-oxadiazole, promotes ribosomal readthrough of premature stop codons in mRNA and offers therapeutic potential for multiple genetic diseases. The authors conducted 2 phase I studies of PTC124 in 62 healthy adult volunteers. The initial, single-dose study evaluated doses of 3 to 200 mg/kg and assessed fed-fasting status on pharmacokinetics following a dose of 50 mg/kg. The subsequent multiple-dose study evaluated doses from 10 to 50 mg/kg/dose twice per day (bid) for up to 14 days. PTC124 administered orally as a liquid suspension was palatable and well tolerated through single doses of 100 mg/kg. At 150 and 200 mg/kg, PTC124 induced mild headache, dizziness, and gastrointestinal events. With repeated doses through 50 mg/kg/dose bid, reversible transaminase elevations <2 times the upper limit of normal were sometimes observed. Immunoblot analyses of peripheral blood mononuclear cell extracts revealed no protein elongation due to nonspecific ribosomal readthrough of normal stop codons. PTC124 plasma concentrations exceeding the 2- to 10-µg/mL values associated with activity in preclinical genetic disease models were safely achieved. No sex-related differences in pharmacokinetics were seen. No drug accumulation with repeated dosing was apparent. Diurnal variation was observed, with greater PTC124 exposures after evening doses. PTC124 excretion in the urine was <2%. PTC124 pharmacokinetics were described by a 1-compartment model. Collectively, the data support initiation of phase II studies of PTC124 in patients with nonsense mutation–mediated cystic fibrosis and Duchenne muscular dystrophy.

23 - (J. Clin. Invest,2007) Interplay of IKK/NF-B signaling in macrophages and myofibers promotes muscle degeneration in Duchenne muscular dystrophy

Swarnali Acharyya, S. Armando Villalta, Nadine Bakkar, Tepmanas Bupha-Intr, Paul M.L. Janssen, Micheal Carathers, Zhi-Wei Li, Amer A. Beg, Sankar Ghosh, Zarife Sahenk, Michael Weinstein, Katherine L. Gardner, Jill A. Rafael-Fortney, Michael Karin, James G. Tidball, Albert S. Baldwin and Denis C. Guttridge -USA

Duchenne muscular dystrophy (DMD) is a lethal X-linked disorder associated with dystrophin deficiency that results in chronic inflammation and severe skeletal muscle degeneration. In DMD mouse models and patients, we find that IB kinase/NF-B (IKK/NF-B) signaling is persistently elevated in immune cells and regenerative muscle fibers. Ablation of 1 allele of the p65 subunit of NF-B was sufficient to improve pathology in mdx mice, a model of DMD. In addition, conditional deletion of IKKß in mdx mice elucidated that NF-B functions in activated macrophages to promote inflammation and muscle necrosis and in skeletal muscle fibers to limit regeneration through the inhibition of muscle progenitor cells. Furthermore, specific pharmacological inhibition of IKK resulted in improved pathology and muscle function in mdx mice. Collectively, these results underscore the critical role of NF-B in the progression of muscular dystrophy and suggest the IKK/NF-B signaling pathway as a potential therapeutic target for DMD.

More informations about IKK/NF-kB:

"Since NF-κB regulation maintains a delicate balance between cell survival and apoptosis and is very important for host defense mechanisms, the specificity and duration of the NF-κB–inhibiting agent becomes highly relevant in designing effective pharmacological therapies against chronic diseases. Whereas IKKβ inhibition in macrophages is beneficial in reducing inflammation in cancer, IKKα loss in macrophages can actually elevate the immune response by increasing the production of proinflammatory cytokines and chemokines, thus underscoring the importance of specificity for IKK inhibitors. Similarly, though administration of nonspecific agents such as MG-132 and, more recently, a synthetic antioxidant ,has been shown to ameliorate the dystrophic phenotype, risks of inhibiting unwanted cellular targets can also sometimes outweigh the benefits. In addition, our inability to detect clear evidence of IκBα degradation in dystrophic muscles may argue against the use of general proteasome inhibitors as a therapeutic strategy for blocking classical NF-κB signaling in DMD. Hence, the implementation of a specific NF-κB inhibitor such as the NBD peptide might provide maximal therapeutic benefit with minimal side effects (. Although long-term inhibition of NF-κB is associated with a vulnerability to bacterial infections and mounting immune responses, it is noteworthy that the NBD peptide has not been found to block basal NF-κB activity and, as seen in this and
previously described studies, does not exhibit overt signs of toxicity. Together, the results identify the IKK/NF-κB signaling
pathway as a viable target for anti-DMD therapy."
 

23 -  (Am. J. Respir. Crit. Care Med. 2007) Leupeptin Inhibits Ventilator-Induced Diaphragm Dysfunction in Rats

Karen Maes, Dries Testelmans, Scott Powers, Marc Decramer, and Ghislaine Gayan-Ramirez - USA

Rationale: Controlled mechanical ventilation has been shown to result in elevated diaphragmatic proteolysis and atrophy along with diaphragmatic contractile dysfunction. Objectives: To test whether administration of leupeptin, an inhibitor of lysosomal proteases and calpain, concomitantly with 24 hours of controlled mechanical ventilation would protect the diaphragm from the deleterious effects of mechanical ventilation. Methods: Rats were assigned to either a control group or 24 hours of controlled mechanical ventilation; animals in the ventilation group received either a single intramuscular injection of saline or 15 mg/kg of the protease inhibitor leupeptin. Measurements and main results: Compared with controls, mechanical ventilation resulted in a significant reduction of the in vitro diaphragm specific force production at all stimulation frequencies. Leupeptin completely prevented this reduction in force generation. Atrophy of type IIx/b fibers was present following controlled mechanical ventilation but not after treatment with leupeptin. Cathepsin B and calpain activities were significantly higher following controlled mechanical ventilation compared to the other groups; this was abolished by treatment with leupeptin. Significant inverse correlations were found between diaphragmatic force generation and cathepsin B and calpain activity and illustrate the deleterious role of proteolysis in diminishing diaphragmatic force production following prolonged controlled mechanical ventilation. Conclusion: Administration of the protease inhibitor leupeptin concomitantly with mechanical ventilation completely prevented ventilation-induced diaphragmatic contractile dysfunction and atrophy.

21- Construction of recombinant adenovirus including microdystrophin and expression in the mesenchymal cells of mdx mice

20 -  (Am J Phys Med Rehabil 2007;86:295-300) Lung Inflation by Glossopharyngeal Breathing and "Air Stacking" in Duchenne Muscular Dystrophy.

Bach JR, Bianchi C, Vidigal-Lopes M, Turi S, Felisari G - USA

Objective: To compare the use of glossopharyngeal breathing (GPB) and air stacking to increase lung volumes and cough peak flows (CPF), and GPB to increase ventilator-free breathing ability (VFBA), for patients with Duchenne muscular dystrophy.

Design: A case series of all referred patients with declining vital capacity (VC). Seventy-eight patients underwent training in and monitoring of the efficacy of air stacking (retaining consecutively delivered volumes of air delivered via manual resuscitator and held by glottic closure) to maximum insufflation capacity (MIC). GPB also was demonstrated to all 78 patients, and 32 were formally trained and prescribed GPB as their VCs decreased below 400 ml. To be successful, the MIC or GPB maximum single-breath capacity (GPmaxSBC) had to exceed VC. Improvements in VFBA were determined by requiring fewer ventilator-assisted breaths per minute. CPFs were measured by peak flow meter.

Results: Seventy-four (94.9%) of the patients could air stack (MIC > VC), and, thus far, 21 (27%) are able to GPB. Fifteen could GPB sufficiently to delay onset of daytime ventilator use and, later, to require 1.9 fewer ventilator assisted breaths per minute. For the 47 patients with multiple data points, as VC deteriorated from 1080 +/- 870 to 1001 +/- 785 ml, MIC increased from 1592 +/- 887 to 1838 +/- 774 ml. For 21 patients, GPmaxSBC significantly exceeded VC (824 +/- 584 vs. 244 +/- 151 ml, respectively, P < 0.001). The ability to increase lung volume by air stacking (MIC) was better retained than was the ability to increase lung volume by GPB (GPmaxSBC). Air stacking also permitted assisted CPF to exceed unassisted CPF: 289 +/- 91 and 164 +/- 76 liters/m, respectively (P < 0.001).

Conclusions: GPB and air stacking can increase lung volumes and, thereby, cough flows. GPB also can be used in many cases to delay and decrease daytime ventilator use.

14 - BM stem cell transplantation rescues pathophysiologic features of aged dystrophic mdx muscle

03 - (Neuromuscular Disorders, 2007) Myostatin does not regulate cardiac hypertrophy or fibrosis

Ronald D. CohN, Hsin-Yueh Liang, Reena Shetty, Theodore Abraham and Kathryn R. WagneR - USA

Myostatin is a negative regulator of muscle growth. Loss of myostatin has been shown to cause increase in skeletal muscle size and improve skeletal muscle function and fibrosis in the dystrophin-deficient mdx muscular dystrophy mouse model. We evaluated whether lack of myostatin has an impact on cardiac muscle growth and fibrosis in vivo. Using genetically modified mice we assessed whether myostatin absence induces similar beneficial effects on cardiac function and fibrosis. Cardiac mass and ejection fraction were measured in wild-type, myostatin-null, mdx and double mutant mdx/myostatin-null mice by high resolution echocardiography. Heart mass, myocyte area and extent of cardiac fibrosis were determined post mortem. Myostatin-null mice do not demonstrate ventricular hypertrophy when compared to wild-type mice as shown by echocardiography (ventricular mass 0.69 ± 0.01 vs. 0.69 ± 0.018 g) and morphometric analyses including heart/body weight ratio (5.39 ± 0.45 vs. 5.62 ± 0.58 mg/g) and cardiomyocyte area 113.67 ± 1.5, 116.85 ± 1.9 μm²). Moreover, absence of myostatin does not attenuate cardiac fibrosis in the dystrophin-deficient mdx mouse (12.2% vs. 12%). The physiological role of myostatin in cardiac muscle appears significantly different than that in skeletal muscle as it does not induce cardiac hypertrophy and does not modulate cardiac fibrosis in mdx mice.

03 - Multinational Trial to Evaluate Steroids in DMD


FEBRUARY

24 - Poloxamer 188 failed to prevent exercise-induced membrane breakdown in mdx skeletal muscle fibers

24 - Streptomycin reduces stretch-induced membrane permeability in muscles from mdx mice.

22 -  (Molecular Biology Cell, 2007) Menstrual Blood-derived Cells Confer Human Dystrophin Expression in the Murine Model of Duchenne Muscular Dystrophy via Cell Fusion and Myogenic Transdifferentiation

ChangHao Cui, Taro Uyama, Kenji Miyado, Masanori Terai, Satoru Kyo, Tohru Kiyono, and Akihiro Umezawa - Japan