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[Myocardial involvement in carrier states for Duchenne muscular dystrophy. A rare cause of supraventricular arrhythmia]
Ruchardt A; Eisenlohr H; Lydtin H
Medizinische Klinik, Krankenhauses des Landkreises Starnberg.
Dtsch Med Wochenschr (Germany) Jul 31 1998, 123 (31-32) p930-5

HISTORY AND CLINICAL FINDINGS: Two women, both aged 54 years, were admitted because of supraventricular arrhythmias of recent onset. Patient 2 was also in heart failure. Male family members of both patients were known to have Duchenne's muscular dystrophy, of which one had died.

INVESTIGATIONS: The electrocardiogram of patient 1 demonstrated atrial fibrillation. Patient 2 had a raised serum creatine kinase concentration and increased pulmonary marking in the chest radiogram. Patient 1 had normal findings on left heart catheterization, but immunohistochemical analysis of a myocardial biopsy revealed dystrophin mosaic with 20% dystrophin-negative fibres. Patient 2 had a reduced ejection fraction and 80% dystrophin-negative fibres.

DIAGNOSIS, TREATMENT AND COURSE: Myocardial involvement in the carrier state for Duchenne's muscular dystrophy having been demonstrated in both women, patient 1 received antihypertensive treatment while patient 2, who was in cardiac failure, was given diuretics, ACE-inhibitor and beta-receptor blockers.

CONCLUSION: Cardiomyopathy in carriers of Duchenne's muscular dystrophy is a rare cause of supraventricular arrhythmias. The cause can be confirmed by immunochemical analysis of an endomyocardial biopsy.

Nine-year follow-up study of heart rate variability in patients with Duchenne-type progressive muscular dystrophy.
Yotsukura M; Fujii K; Katayama A; Tomono Y; Ando H; Sakata K; Ishihara T; Ishikawa K
The Second Department of Internal Medicine, Kyorin University School of Medicine, Tokyo, Japan.
Am Heart J (United States) Aug 1998, 136 (2) p289-96

OBJECTIVES: The purpose of this study was to investigate the progression of autonomic dysfunction in patients with Duchenne-type progressive muscular dystrophy (DMD) over time by using heart rate variability.

BACKGROUND: Although previous studies suggest the presence of autonomic dysfunction in patients with DMD, the precise cause is not known. On the other hand, it is well known that analysis of heart rate variability provides a useful, noninvasive means of quantifying autonomic activity. High frequency power is determined predominantly by the parasympathetic nervous system, whereas low frequency power is determined by both the parasympathetic and sympathetic nervous systems.

METHODS AND RESULTS: Frequency and time domain analyses of heart rate variability during ambulatory electrocardiographic monitoring were performed in 17 patients with DMD over a 9-year period. At the time of entry, the mean patient age was 11 years and the mean Swinyard-Deaver stage was 4. In the first year, high frequency power was significantly lower and the ratio of low frequency to high frequency was significantly higher in patients with DMD than in the normal control subjects. These differences become significantly greater as the disease progressed. At the time of entry, low and high frequency powers increased at night in both groups. However, over time, high and low frequency powers at night tended to decrease. All of the time domain parameters were significantly lower in the patients with DMD at all time points compared with the normal control subjects.

CONCLUSIONS: We concluded that DMD patients have either a decrease in parasympathetic activity, an increase in sympathetic activity, or both as their disease progresses.

Spinal instrumentation for Duchenne's muscular dystrophy: experience of hypotensive anaesthesia to minimise blood loss
Fox HJ; Thomas CH; Thompson AG
Birmingham Orthopaedic Spinal Service, England.
J Pediatr Orthop (United States) Nov-Dec 1997, 17 (6) p750-3

Nineteen patients with Duchenne's muscular dystrophy underwent segmental spinal instrumentation and posterior fusion between 1989 and 1994. The indication for surgery was loss of the ability to walk and development of scoliosis with sitting discomfort. Preoperative assessment included evaluation of pulmonary function. Average age at operation was 12.5 years. Instrumentation and fusion extended from upper thoracic levels to L-5 or the sacrum. A Hartshill rectangle was used in all cases, with banked allograft bone. Severe intraoperative blood loss was avoided by use of hypotensive anaesthesia. Peroperatively, systolic blood pressure was maintained between 75 and 85 mm Hg. Average blood loss was 1,246 ml (range, 400-3,100) or 30% of estimated total blood volume. Average transfusion requirements were 3 units of packed cells. Postoperative analgesia was provided by infusion via an epidural catheter. There were no postoperative wound or chest infections. Three patients required catheterisation for urinary retention. Postoperatively patients were fitted with a Neofract jacket to allow early mobilisation and discharge. Mean postoperative length of stay was 16 days. Posterior spinal fusion by using the Hartshill rectangle provided good correction and fixation. Hypotensive anaesthesia permitted surgery to be performed rapidly in a relatively dry field and avoided the complications of severe intraoperative blood loss and massive transfusion.

Duchenne muscular dystrophy: a model for studying the contribution of muscle to energy and protein metabolism.
Hankard R
Centre d'investigation clinique, Hopital Robert-Debre, Paris, France.
Reprod Nutr Dev (France) Mar-Apr 1998, 38 (2) p181-6

Duchenne muscular dystrophy (DMD) is associated with a dramatic muscle mass loss. We hypothesized that DMD would be associated with significant changes in both energy and protein metabolism. We studied the resting energy expenditure (REE) in DMD and control children using indirect calorimetry, and their protein metabolism using an intravenous infusion of leucine and glutamine labeled with stable isotopes. In spite of a 75% muscle mass loss in the DMD children, the REE only decreased by 10%. DMD was associated with increased leucine oxidation but neither protein degradation nor protein synthesis were different from that of the controls. In contrast, whole body turnover of glutamine, an amino acid mainly synthesized in the muscle, was significantly decreased. These studies emphasized the quantitatively poor contribution of muscle to energy and protein metabolism in children. The qualitative impact of muscle mass loss on amino acid metabolism (glutamine) offers a fascinating field of research for the next few years and has therapeutic potential. (24 Refs.)

The molecular basis of activity-induced muscle injury in Duchenne muscular dystrophy.
Petrof BJ
Department of Medicine, Royal Victoria Hospital, McGill University, Montreal, Quebec, Canada.
Mol Cell Biochem (Netherlands) Feb 1998, 179 (1-2) p111-23

Duchenne muscular dystrophy (DMD) is the most common of the human muscular dystrophies, affecting approximately 1 in 3500 boys. Most DMD patients die in their late teens or early twenties due to involvement of the diaphragm and other respiratory muscles by the disease. The primary abnormality in DMD is an absence of dystrophin, a 427 kd protein normally found at the cytoplasmic face of the muscle cell surface membrane. Based upon the predicted structure and location of the protein, it has been proposed that dystrophin plays an important role in providing mechanical reinforcement to the sarcolemmal membrane of muscle fibers. Therefore, dystrophin could help to protect muscle fibers from potentially damaging tissue stresses developed during muscle contraction. In the present paper, the nature of mechanical stresses placed upon myofibers during various forms of muscle contraction are reviewed, along with current lines of evidence supporting a critical role for dystrophin as a subsarcolemmal membrane-stabilizing protein in this setting. In addition, the implications of these findings for exercise programs and other potential forms of therapy in DMD are discussed. (93 Refs.)

Social adjustment in adult males affected with progressive muscular dystrophy.
Eggers S; Zatz M
Centro de Miopatias, Departamento de Biologia, Universidade de Sao Paulo, Brazil
Am J Med Genet (United States) Feb 7 1998, 81 (1) p4-12

Adult male patients affected with Becker (BMD, N = 22), limb girdle (LGMD, N = 22) and facioscapulohumeral (FSHMD, N = 18) muscular dystrophy were interviewed to assess for the first time how the disease's severity and recurrence risk (RR) magnitude alter their social adjustment. BMD (X-linked recessive) is the severest form and confers an intermediate RR because all daughters will be carriers, LGMD (autosomal-recessive) is moderately severe with a low RR in the absence of consanguineous marriage, and FSHMD (autosomal-dominant) is clinically the mildest of these three forms of MD but with the highest RR, of 50%. Results of the semistructured questionnaire [WHO (1988): Psychiatric Disability Assessment Schedule] showed no significant difference between the three clinical groups, but more severely handicapped patients as well as patients belonging to lower socioeconomic levels from all clinical groups showed poorer social adjustment. Taken together, myopathic patients displayed intermediate social dysfunction compared to controls and schizophrenics studied by Jablensky [1988: WHO Psychiatric Disability Assessment Schedule]. Since the items of major dysfunction proportion among myopathic patients concern intimate relationships (70%), interest in working among those unemployed (67%), and social isolation (53%), emotional support and social and legal assistance should concentrate on these aspects. Interestingly, the results of this study also suggest that high RRs do not affect relationships to the opposite sex.

[Genetic diagnosis of Duchenne/Becker muscular dystrophy; clinical application and problems]
Takeshima Y
Department of Pediatrics, Kobe University School of Medicine.
No To Hattatsu (Japan) Mar 1998, 30 (2) p141-7

Duchenne/Becker muscular dystrophies (DMD/BMD) are the most common inherited muscular disease and caused by mutations in the dystrophin gene. A half to two-thirds of DMD and BMD patients carry deletions (usually of several kilobases of genomic DNA). The clinical progression in DMD and BMD patients with deletions can be predicted in 92% of cases based on whether the deletion maintains or disrupts the translational reading frame (frame-shift hypothesis). However, some exceptional cases have been reported in which some posttranscriptional modifications were suggested, such as alternative splicing and reinitiation of translation. Splicing mutation is one kind of mutations of dystrophin gene, and usually induced by a small mutation of exon-intron boundary sequence. However, intraexonal small mutation also induces exon skipping, due to disruption of an exon recognition sequence, which is an intraexonal sequence and necessary for splicing of the upstream intron. Carrier diagnosis is one of the important clinical application of genetic diagnosis. In the case of DMD/BMD with deletions of the dystrophin gene, carrier diagnosis is difficult because of the existence of normal X chromosome. In these cases a linkage analysis is useful, and in some cases non-carriers can be directly diagnosed on the basis of microsattelite polymorphism detected in deleted region of patient. For the molecular diagnosis of DMD/BMD it is important to analyze not only at the genomic DNA level, but also at the mRNA, protein, and clinical levels. And the relationship between the molecular abnormality and clinical phenotype should be examined, especially extramuscular symptoms such as heart failure and mental retardation.

[Detection of mutation in dystrophin gene in Duchenne muscular dystrophy--multiplex PCR and Southern blot analysis]
Kawamura J
Department of Internal Medicine, National Higasisaitama Hospital.
Nippon Rinsho (Japan) Dec 1997, 55 (12) p3126-30

The genetic defect responsible for Duchenne muscular dystrophy (DMD) can be identified as a partial deletion of the dystrophin gene in 50% of cases, or as a partial duplication in a further 10%. Multiplex PCR has been applied to screening of mutations in dystrophin gene, and it can identify 98% of deletions detected by Southern blot analysis. However, PCR cannot be available for quantifying DNA, so that detection of carrier status or duplication cannot be identified by multiplex PCR. Quantitative analysis of Southern blot hybridization is the most widely used and reliable method for detection of carrier and duplication mutation in dystrophin gene, but this method is a technically demanding procedure. (10 Refs.)

Scoliosis in Duchenne muscular dystrophy : aspects of orthotic treatment.
Heller KD; Forst R; Forst J; Hengstler K
Orthopaedic Department, University Clinic RWTH Aachen, Germany.
Prosthet Orthot Int (Denmark) Dec 1997, 21 (3) p202-9

The x-linked Duchenne muscular dystrophy (DMD) is the most frequent generalized muscle disorder arising from a lack of the sarcolemmic protein "dystrophin". Patients with DMD develop in the majority a progressive scoliosis when they cease walking and/or standing at the age of 10 years and become confined to a wheelchair. Increasing muscle weakness leads to a progression of the curvature, the pelvic tilt and problems in sitting. Together with the simultaneous progressive weakness of the respiratory muscles a restrictive pulmonary insufficiency will occur. Surgical stabilization of the spine (> 20 degrees Cobb, forced vital capacity > 35%) by an adequate multisegmental instrumentation enabling early mobilization is now the treatment of choice. However, orthotic treatment may offer an acceptable compromise in exceptional cases, if the patient rejects surgical intervention or is in the late (inoperable) stages of the disease. Such a treatment is superior to a primary sitting support provision with insufficient possibilities of correction. The authors' experiences with 48 scoliosis orthoses made for 28 patients with DMD are reported. A "double plaster" cast has emerged as the best method to optimize adaption, especially in severe curvatures and the time taken for manufacturing the orthosis. A great deal of experience, patience and the consideration of the patients' individual demands are inevitable for a successful orthotic treatment.

Challenges in Duchenne muscular dystrophy.
Davies KE
Department of Biochemistry, University of Oxford, UK.
Neuromuscul Disord (England) Dec 1997, 7 (8) p482-6

The last seven years has witnessed an explosion in our understanding of the muscular dystrophies. In the early 1980s, prenatal diagnosis of Duchenne muscular dystrophy was developed. The cloning of the gene, in 1996, resulted in a better understanding of the disease process and led to the identification of a novel complex at the membrane. This information led to the cloning of other genes responsible for the autosomally inherited dystrophies. As we approach the millenium, the challenge is shifting to the development of therapy of these diseases. This review, in honour of Professor Alan Emery, explains how these advances have an impact in the clinical management of patients and head the promise the progress holds for the future. (47 Refs.)

Problems and potential for gene therapy in Duchenne muscular dystrophy.
Kakulas BA
Australian Neuromuscular Research Institute, Perth, Australia.
Neuromuscul Disord (England) Jul 1997, 7 (5) p319-24

Hopes ran high that a cure for Duchenne muscular dystrophy (DMD) would quickly follow the discovery of dystrophin by Lou Kunkel and his group in the 1980's. Myoblast transplantation, the favoured method of gene 'complementation', unfortunately did not progress beyond the experimental stage. A more sober approach to gene therapy followed using a variety of transfection or direct methods to introduce the normal gene. In view of these advances it is timely for the potential of gene therapy for DMD to be considered in the light of the disease process. It may be assumed that if dystrophin is replaced muscle fibre necrosis will cease. For this purpose expression of the gene should be continuous and expressed throughout the body well before there are irreversible changes. It would seem that gene therapy would not be particularly helpful if this occurs when the muscle lesions are near the end stage. If our objective is to retain ambulation dystrophin must be replaced well before the end stage. It should be kept in mind that even when the disorder first becomes clinically apparent at the age of about 5 years, muscle lesions are very advanced in the limb girdle groups. Therefore, the best that may be hoped to achieve by gene therapy at the age of 5 years would be to arrest the process at that stage of involvement with the patient having permanent but static weakness. Cardiac lesions are probably minimal at this time. To improve life expectancy, the respiratory muscles would need to be preserved. The enormous size of the gene is another difficulty so that some thought has been given to the introduction of a 'minigene' converting the clinical phenotype from DMD to the more benign Becker phenotype with improved life expectancy.

Improved adenoviral vectors for gene therapy of Duchenne muscular dystrophy.
Hauser MA; Amalfitano A; Kumar-Singh R; Hauschka SD; Chamberlain JS
Department of Human Genetics, University of Michigan Medical School, Ann Arbor 48109-0618, USA.
Neuromuscul Disord (England) Jul 1997, 7 (5) p277-83

We have been exploring the feasibility of gene therapy for Duchenne muscular dystrophy by characterizing parameters important for the design of therapeutic protocols. These studies have used transgenic mice to analyze expression patterns of multiple dystrophin vectors, and have been accompanied by the development of viral vectors for gene transfer to dystrophic mdx mouse muscle. Analysis of transgenic mdx mice indicates that greater than 50% of the fibers in a muscle group must express dystrophin to prevent development of a significant dystrophy, and that low-level expression of truncated dystrophins can function very well. These results suggest that gene therapy of DMD will require methods to transduce the majority of fibers in critical muscle groups with vectors that express moderate levels of dystrophin proteins. Strategies for the development of viral vectors able to deliver dystrophin genes to muscle include the use of muscle specific regulatory sequences coupled with deletion of viral gene sequences to limit virus-induced immune rejection of transduced tissues. These strategies should enable production of adenoviral vectors expressing full-length dystrophin proteins in muscle.

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