Évaluation d'une procédure antalgique associant protoxyde d'azote et crème EMLA lors des injections de toxine botulique chez l'enfant

AIMS

To evaluate the efficiency and tolerance of analgesic treatment with nitrous oxide and topical eutectic mixture of local anesthetics (EMLA) in children undergoing botulinum toxin injections for focal spasticity.

METHODS

Prospective study including 40 consecutive patients aged 2 to 17 years, most with cerebral palsy, undergoing botulinum toxin injections. Ten had severe cerebral palsy with cognitive deficiency. For most patients the treatment involved several muscles, with several injections per muscle. The total number of injections varied from 1 to 25. The procedure was performed with topical anesthesia with EMLA and inhalation of nitrous oxide (50% nitrous oxide, 50% oxygen). Reactions were recorded by the staff (a practician, a nurse, an auxiliary staff member and an internist) and whether they related to the injection or were nonspecific.

RESULTS

A total of 45% of patients showed no clinical manifestation of pain; for 30%, reactions were crying and withdrawal directly related to the injections; and for 25%, manifestations seemed nonspecific and mainly related to overall anxiety and discomfort. In 3 patients, moderate side effects were observed (visual hallucinations and euphoria).

DISCUSSION

Nitrous oxide analgesic with topical EMLA was efficient for children undergoing botulinum toxin injections but remained insufficient for half of our patients, and modification of the protocol is needed in some cases. Precise evaluation of acute pain is difficult in children with major cognitive deficits. Clinical manifestations are related to pain but also to overall anxiety and stress.

Zaspopathy in a large classic late-onset distal myopathy family

Distal myopathies have been associated with mutations in titin, dysferlin, GNE, desmin and myosin. Of these, only titin mutations were previously known to cause dominant late-onset distal myopathy. Recent findings, however, have indicated that patients affected with myofibrillar myopathy have a more distal than proximal muscle phenotype and a proportion of these may have mutations in myotilin, ZASP or filamin C, besides previously known desmin and alphaB-crystallin. Here we report that the disorder in one of the well-characterized autosomal dominant distal myopathy families, the Markesbery et al. family, first reported in 1974, is caused by ZASP mutation A165V. Previous linkage to the titin locus 2q31 proved incorrect. ZASP expression by immunoblotting shows normal presence of the main 32 and 78 kDa bands and immunohistochemistry in patients reveals normal Z-disc localization except for moderate accumulations together with myotilin, desmin alphaB-crystallin and alpha-actinin. Muscle imaging reveals involvement in both the posterior and anterior compartments of the lower leg and considerable affection of proximal leg muscles at later stages. Haplotype studies in this family and in five other unrelated families with European ancestry carrying the identical A165V mutation share common markers at the locus suggesting the existence of a founder mutation.

AAV-mediated delivery of a mutated myostatin propeptide ameliorates calpain 3 but not α-sarcoglycan deficiency

Myostatin is a negative regulator of muscle mass whose inhibition has been proposed as a therapeutic strategy for muscle-wasting conditions. Indeed, blocking myostatin action through different strategies has proved beneficial for the pathophysiology of the dystrophin-deficient mdx mouse. In this report, we tested the inhibition of myostatin by AAV-mediated expression of a mutated propeptide in animal models of two limb-girdle muscular dystrophies: LGMD2A caused by mutations in the calpain 3 (CAPN3) gene and LGMD2D caused by mutations in the alpha-sarcoglycan gene (SGCA). In the highly regenerative Sgca-null mice, survival of the alpha-sarcoglycan-deficient muscle fibers did not improve after transfer of the myostatin propeptide. In calpain 3-deficient mice, a boost in muscle mass and an increase in absolute force were obtained, suggesting that myostatin inhibition could constitute a therapeutic strategy in this predominantly atrophic disorder.

The genetic and molecular bases of monogenic disorders affecting proteolytic systems

Complete and limited proteolysis represents key events that regulate many biological processes. At least 5% of the human genome codes for components of proteolytic processes if proteases, inhibitors, and cofactors are taken into account. Accordingly, disruption of proteolysis is involved in numerous pathological conditions. In particular, molecular genetic studies have identified a growing number of monogenic disorders caused by mutations in protease coding genes, highlighting the importance of this class of enzymes in development, organogenesis, immunity, and brain function. This review provides insights into the current knowledge about the molecular genetic causes of these disorders. It should be noted that most are due to loss of function mutations, indicating absolute requirement of proteolytic activities for normal cellular functions. Recent progress in understanding the function of the implicated proteins and the disease pathogenesis is detailed. In addition to providing important clues to the diagnosis, treatment, and pathophysiology of disease, functional characterisation of mutations in proteolytic systems emphasises the pleiotropic functions of proteases in the body homeostasis.

Noninvasive monitoring of therapeutic gene transfer in animal models of muscular dystrophies

Muscular dystrophies are a genetically and phenotypically heterogeneous group of degenerative muscle diseases. A subset of them are due to genetic deficiencies in proteins which form the dystrophin-associated complex at the membrane of the myofibers. In this report, we utilized recombinant adeno-associated virus containing a U7 cassette carrying an antisense sequence aimed at inducing exon skipping of the dystrophin gene or containing the alpha-sarcoglycan gene to alleviate the dystrophic phenotype of the mdx and Sgca-null mice, respectively. As these diseases are characterized by cycle of degeneration/regeneration, we postulated that a reporter gene coadministered at the time of the treatment would make it possible to follow the extent of muscle repair. We observed that the murine secreted alkaline phosphatase (muSeAP) level was very much lower in these animal models than in normal mice. Upon treatment of the dystrophic muscle by gene transfer, the level of muSeAP was restored and correlated with the expression of the therapeutic transgene and with the level of muscle improvement. The system described here provides a simple and noninvasive procedure for monitoring the outcome of a therapeutic strategy involving cell survival.

Évaluation de l'attitude vis-à-vis des personnes handicapées des étudiants en médecine de 3e et 4e année par le questionnaire « Attitude towards disabled persons ». Effets de l'enseignement théorique et de stages dans les services de médecine physique et réadaptation

Modifications of the medical curriculum have included a compulsory course on disability.

OBJECTIVE

To determine whether attendance in a course on disability and/or rotations in physical medicine and rehabilitation departments modify the attitude of medical students towards disabled people.

METHODS

All third- and fourth-year students completed a translated version of the ATDPb. This questionnaire rates items evaluating attitude towards disabled people on a 6-point scale (minimum 0; maximum 180). Retro-translation was performed to control the translation. During the second year, all students had attended a general course in ethics. Fourth-year students had attended a 17 hours course on disability, and 21 of 78 had spent 9 weeks in the physical medicine and rehabilitation department. The study compares fourth-year students to third-year students, considered as controls, and students having spent a rotation in the physical medicine and rehabilitation department to others.

RESULTS

The mean score of all students was 108.86+/-15.84 (73-160) on the ATDP scale. Males and females did not differ significantly, and the score did not change from that before the course on disability (109.95+/-14.98 vs 107.6+/-16.65, P=0.23) nor after a rotation in the physical medicine and rehabilitation department (113.52+/-11.42 vs 108.54+/-16.03, P=0.14).

CONCLUSION

Development and validation of scores that would fit better to the European cultural context would be useful. The present method of theoretical courses and rotations do not improve the attitude of students towards disabled people and should be modified if this objective is to be achieved.

Santé publique et traumatismes crâniens graves. Aspects épidémiologiques et financiers, structures et filières de soins

The management of persons with traumatic brain injury affects a large spectrum of interventions from acute phase to the hospital discharge and the return to community. The incidence of brain injuries on mortality and morbidity constitutes a serious problem in front of the Health Administration. The traffic accidents remain the main cause but the falls in elderly are increasing. In the both cases preventive measures can be efficiency. In France, each year, there are about 150,000 new cases, 8000 of them will be dead and 4000 with coma. It is likely that 30,000 persons are living to day with important sequela of a brain injury. The management requires various types of interventions, each of them with specific and specialized techniques. It is necessary to have an overview of the problem and to work together in a comprehensive network. So French Health Ministry has just published an official note to precise some directives and co-ordination of the different interventions.

Trachéotomie et traumatisme crânien grave : pour qui ? Pourquoi ? Quand ? Comment ?

The aim of this study is to determine, from the data available in the literature, the indications of tracheostomy in brain injured patients, the incidence and risk factors for complications and the follow-up required until decannulation. The incidence of tracheostomy is 10% in TBI and 50 to 70% in subpopulations with a Glasgow Coma Scale (GCS) below 9. Early complications are not specific. The most frequent late complication is laryngotracheal stenosis, which occurs in 15% and is more frequently observed in the most severe patients with major hypertonia. It is likely that tracheostomy, if needed, should be performed early and the prognosis as to whether it will be required, can be made at the end of the first week. The follow-up of these patients includes surveillance of multiresistant colonisations and systematic performance of fibroscopy before decannulation. Cuffless, small diameters, soft tracheostomy tubes, are preferred on the long-term unless the risk of aspiration remains high.

[Gait orthosis in patients with complete thoracic paraplegia. Review of 43 patients]

OBJECTIVE

To evaluate of the effective use of gait orthosis in patients with spinal cord injuries.

PATIENTS AND METHODS

A total of 43 patients with complete paraplegia, level T3 to L1, who had a gait orthosis (hip-knee-ankle-foot orthosis, reciprocating gait orthosis, hybrid orthosis and functional electrical stimulation) answered a telephone questionnaire.

RESULTS

Orthotic gait use was discontinued in 65% of patients who used the orthosis twice a week for 15 to 60 minutes. Two-thirds of the patients were able to fit the orthosis independently, 60% for standing and 25% for walking. The main reasons for discontinuing use were psychological reasons in 30% of patients, the lack of functional use and the necessity for human help or supervision.

CONCLUSION

Presently available devices do not allow functional and independent use of gait orthoses. Their use is limited to physical training, and the only demonstrated physiological benefits are the effects of functional electrical stimulation on cardiovascular status. Prescription for gait orthosis appears justified only if requested by a motivated and well-informed patient or if it appears a useful step in the acceptation of the loss of the gait.

Membres supérieurs fonctionnels hypertoniques et toxine botulique. Quels résultats fonctionnels ?

OBJECTIVES

To assess the efficacy of botulinum toxin injections for hypertonic upper limbs in patients with residual motricity that allows a functional use of the hand.

METHODS

Patients were seen between February 2000 and November 2002, before and after botulinum toxin injections for hypertonic upper limbs due to upper motor neuron syndrome. All patients had voluntary motricity in fingers and wrist extensors. Impairment (range of motion, spasticity [Ashworth's scale]), pain (10 centimeters visual analog scale) prehension (400-point measure) and patients' satisfaction were recorded. Two or three functional goals were predefined. Patients were injected after locating the target area with neurostimulation. The aim of the injections was functional improvement.

RESULTS

Eight patients were included. After injections, mean pain score decreased by 3.4 points; mean spasticity decreased by 1.0; and prehension improved, especially for bimanual functions. Three-quarters of the functional goals were reached. Optimal efficacy required repeated injections, with modification of muscle targets and doses.

CONCLUSION

Botulinum toxin injection is efficient for impairment, pain and prehension in hypertonic upper limbs, even if the hypertonic hand is still the "nondominant" hand. Motricity in antagonist muscles is essential for functional improvement, and the assessment must include bimanual tasks. Intrinsic as well as extrinsic muscles must be injected and a neurostimulator used for forearm muscles. Comparative studies are required to define more clearly the place of this treatment among medical and surgical treatments of spasticity.

Titinopathies and extension of the M-line mutation phenotype beyond distal myopathy and LGMD2J

OBJECTIVE

To determine the phenotype variability associated with the specific C-terminal M-line titin mutation known to cause autosomal dominant distal myopathy, tibial muscular dystrophy (TMD; MIM 600334), and limb girdle muscular dystrophy 2J (LGMD2J).

METHODS

Three hundred eighty-six individuals were genotyped for the Finnish founder mutation in titin (FINmaj) causing TMD/LGMD2J.

RESULTS

Two hundred seven patients were heterozygous for the mutation. Among these patients, 189 (91%) had a more common phenotype compatible with the classic description of TMD. However, 18 (9%) had unusual phenotypes such as proximal leg or posterior lower leg muscle weakness and atrophy even at onset. Four patients were confirmed homozygotes representing the LGMD2J phenotype. These homozygotes were half of the eight LGMD patients previously described in the original large consanguineous kindred.

CONCLUSIONS

Large variability of phenotypic expression caused by just one mutation, the Finnish FINmaj, suggests that no certain phenotype of myopathy/dystrophy can be excluded from being caused by mutated titin. Yet unknown homozygous or compound heterozygous titin mutations without phenotype in the heterozygote carriers may be responsible for undetermined recessive MD and LGMD.

Treatment of spasticity with intrathecal Baclofen administration: long-term follow-up, review of 40 patients

STUDY DESIGN

Case series of a consecutive sample. Retrospective audit.

OBJECTIVE

To analyze the long-term safety and efficacy of intrathecal baclofen (ITB), and technical incidents.

SETTING

Neurosurgical and Physical Medicine Departments of two university hospitals in western France.

METHODS

The medical records of 40 patients who underwent ITB pump placement for the treatment of severe chronic spasticity were reviewed. Patients were eligible independently of the origin of the spasticity (spinal cord origin 33, brain damage 8). They underwent a final assessment with clinical examination and questionnaire in 2001. Ashworth scale scores were assessed, patient satisfaction was rated on a visual analog scale (VAS), functional independence before and after treatment was classified as bed-ridden, wheelchair dependent or ambulant, and the frequency and nature of complications were noted.

RESULTS

The average follow-up period was of 4 years. The average Ashworth score at the final assessment was 1.8+/-0.6. Average patients satisfaction was 7.4/10+/-2.21 on VAS. In all, 85% would have undergone the procedure again if they had to make the decision. In 85% of the cases the ambulation status was unchanged. Technical incidents occurred at least once in 37% of the patients (due to the catheter in 58% and to the pump in 42%). They included catheter disconnections (4), migration (4), kinks (3), obstruction (3), development of fibrosis (3), disconnection of pump reservoir (2), porosity of pump membrane (2), unexplained pump dysfunction (4) leakage, and subcutaneous collection (5). Severe pharmacological side effects requiring transfer to intensive care unit occurred in 12% of cases, 80% of which were directly related to pump refill procedures.

CONCLUSION

ITB remained effective in the long term and patients were satisfied. Nevertheless, complications were frequent, involving mainly the catheters, which would require further technical improvements.

Impact de programmes de restauration fonctionnelle sur les peurs, croyances et conduites d’évitement du lombalgique chronique

OBJECTIVE

To assess the impact of functional restoration programs on fears, avoidance and beliefs in chronic low back pain.

METHODS

Open prospective study in eight spine centers. Seventy patients enrolled in several restoration programs were evaluated before and at the end of the program. Variables recorded were pain (VAS), disability (Quebec back pain disability scale), handicap (VAS), anxiety and depression (HAD scale), and fears, avoidance and beliefs (FABQ).

RESULTS

All variables recorded significantly improved at the end of the programs except for fears about professional activities (FABQ1) and lumbar mobility. Fears about physical activities (FABQ2) significantly decreased after these programs. Variations in FABQ1 and FABQ2 scores were not correlated with variations in scores of outcome measures assessing impairment, disability, and handicap.

CONCLUSION

Functional restoration programs in their current form in France do not decrease fears and beliefs about professional activities in chronic low back pain patients. Adding psychosocial intervention at the work place to the functional restoration programs may lead to a better impact on fears about work thus reducing work loss.

Lower limb proximal amputation for a tumour: a retrospective study of 12 patients

OBJECTIVE

To analyse survival, prosthetic fitting and functional status after trans-femoral amputation or hip disarticulation for a primitive tumour.

METHODS

Retrospective study of all patients admitted since 1985.

RESULTS

Mean age at amputation was 55. Causes of amputation were osteosarcoma in 50%. Eight (8) patients had initial conservative surgery. Local recurrence was never observed. Nine (9) developed metastasis and required further hospitalisation. Fifty percent (50%) of patients died. Inpatient rehabilitation started 14 days after amputation (7-27), and was of a mean duration of 32 days. Prosthetic fitting was performed 13 days after admission (7 days when a liner was used). Further improvement of the prosthesis was performed in 10 patients. Among the patients who died, 5 had gone home, 4 were wearing their prosthesis all day long and 2 walked indoors with no additional support at discharge. Three (3) patients lived less than 2 months at home. Among the patients who did survive, all went home, 5 were wearing their prosthesis all day long and 2 walked indoors without aid at discharge. Two (2) patients practised sport and 4 drove. All the patients who were active have gone back to work.

CONCLUSIONS

Gain due to prosthesis provision is undebatable. Good functional results can be obtained with adapted materials. Initial problems due to the synchronisation of treatments are resolved with multidisciplinary care. All patients should have a rapid and short hospitalisation in a rehabilitation unit and receive a first, simple prosthesis that can be further adapted.

Effects of agonists of peroxisome proliferator-activated receptor gamma on proteoglycan degradation and matrix metalloproteinase production in rat cartilage in vitro

OBJECTIVE

To examine the effects of agonists of peroxisome proliferator-activated receptor (PPAR) gamma on proteoglycan degradation induced by interleukin (IL)-1beta or tumor necrosis factor (TNF)alpha in cartilage in vitro.

DESIGN

Proteoglycan degradation was measured as release of radioactivity from rat cartilage explants previously labeled with (35)SO2-4. Western blots were used to examine tissue levels of aggrecan neoepitopes NITEGE and VDIPEN, generated by aggrecanases and matrix metalloproteinases (MMP), respectively. Production of MMP-2, -3 and -9 by cultured rat chondrocytes was measured by zymography and by fluorimetric assay.

RESULTS

IL-1beta-induced proteoglycan degradation was likely due to aggrecanase, since it was associated with a strong increase of NITEGE signal. MMP-dependent VDIPEN signal increased only after further incubation with pro-MMP activator APMA. PPAR agonists 15d-PGJ(2) and GI262570 (10 microM) inhibited IL-1beta- and TNFalpha-induced proteoglycan degradation measured both before and after addition of APMA. The agonists also inhibited cytokine-induced MMP production by isolated chondrocytes.

CONCLUSION

This study shows that PPARgamma agonists inhibit cytokine-induced proteoglycan degradation mediated by both aggrecanase and MMP. This effect is associated with inhibition of production of MMP-3 and -9. These results support the interest for PPARgamma agonists as candidate inhibitors of pathological cartilage degradation.

Molecular adaptations of neuromuscular disease-associated proteins in response to eccentric exercise in human skeletal muscle

The molecular events by which eccentric muscle contractions induce muscle damage and remodelling remain largely unknown. We assessed whether eccentric exercise modulates the expression of proteinases (calpains 1, 2 and 3, proteasome, cathepsin B+L), muscle structural proteins (alpha-sarcoglycan and desmin), and the expression of the heat shock proteins Hsp27 and alphaB-crystallin. Vastus lateralis muscle biopsies from twelve healthy male volunteers were obtained before, immediately after, and 1 and 14 days after a 30 min downhill treadmill running exercise. Eccentric exercise induced muscle damage as evidenced by the analysis of muscle pain and weakness, creatine kinase serum activity, myoglobinaemia and ultrastructural analysis of muscle biopsies. The calpain 3 mRNA level was decreased immediately after exercise whereas calpain 2 mRNA level was increased at day 1. Both mRNA levels returned to control values by day 14. By contrast, cathepsin B+L and proteasome enzyme activities were increased at day 14. The alpha-sarcoglycan protein level was decreased immediately after exercise and at day 1, whereas the desmin level peaked at day 14. alphaB-crystallin and Hsp27 protein levels were increased at days 1 and 14. Our results suggest that the differential expression of calpain 2 and 3 mRNA levels may be important in the process of exercise-induced muscle damage, whereas expression of alpha-sarcoglycan, desmin, alphaB-crystallin and Hsp27 may be essentially involved in the subsequent remodelling of myofibrillar structure. This remodelling response may limit the extent of muscle damage upon a subsequent mechanical stress.

Stable expression of calpain 3 from a muscle transgene in vivo: immature muscle in transgenic mice suggests a role for calpain 3 in muscle maturation

Limb-girdle muscular dystrophy, type 2A (LGMD 2A), is an autosomal recessive disorder that causes late-onset muscle-wasting, and is due to mutations in the muscle-specific protease calpain 3 (C3). Although LGMD 2A would be a feasible candidate for gene therapy, the reported instability of C3 in vitro raised questions about the potential of obtaining a stable, high-level expression of C3 from a transgene in vivo. We have generated transgenic (Tg) mice with muscle-specific overexpression of full-length C3 or C3 isoforms, which arise from alternative splicing, to test whether stable expression of C3 transgenes could occur in vivo. Unexpectedly, we found that full-length C3 can be overexpressed at high levels in vivo, without toxicity. In addition, we found that Tg expressing C3 lacking exon 6, an isoform expressed embryonically, have muscles that resemble regenerating or developing muscle. Tg expressing C3 lacking exon 15 shared this morphology in the soleus, but not other muscles. Assays of inflammation or muscle membrane damage indicated that the Tg muscles were not degenerative, suggesting that the immature muscle resulted from a developmental block rather than degeneration and regeneration. These studies show that C3 can be expressed stably in vivo from a transgene, and indicate that alternatively spliced C3 isoforms should not be used in gene-therapy applications because they impair proper muscle development.

[Heparin induced thrombocytopenia: case report with acute thrombotic complications and literature review]

PURPOSE

Review of the frequency, clinical and biological features and treatment of type II heparin-induced thrombocyopenia.

METHODS

Case report and literature review.

RESULTS

A 65 years old woman received as antithrombotic prophylaxis low molecular weight heparin (LMWH) after prosthetic knee replacement. Day 8, asymptomatic deep vein thrombosis was discovered after systematic echodoppler examination. Curative anticoagulation was started with LMWH. A fall in the platelet count (17 G/L) was noted day 12. Danaparoid was immediately introduced and heparin discontinued. However, day 16 a massive pulmonary embolism occurred which required transfer to an intensive care unit. Danaparoid was changed for lepirudin the same day. It took longer than three weeks for platelet count to return to normal value after heparin discontinuation. The suspicion of heparin-induced thrombocyopenia was confirmed by specific tests.

DISCUSSION

HIT type II are rare but life-threatening and thrombosis events are the most frequent complications. The diagnosis is a high probability proved by both clinical and biological patterns. The treatment consists in alternative thrombin inhibitors such as danaparoid and lepirudin. The platelet count usually requires less than ten days to recover normal values after heparin withdrawal. Cases in which the delay to a normal platelet count exceeds 3 weeks have been reported specially after LMWH therapy.

CONCLUSION

Type II HIT are rare but life-threatening events can occur. The platelet count check-up during heparin therapy must be systematic.

[Total inverted shoulder prosthesis and rotator cuff insufficiency: evaluation and determination of anatomical parameters predictive of good functional outcome in 21 shoulders]

OBJECTIVE

Evaluation of the functional results of the Delta 3 inverted shoulder prosthesis and determination of a radio-anatomical index predictive of best functional outcome.

PATIENTS AND METHODS

Retrospective analysis of 19 patients (21 shoulders). Clinical (pain, satisfaction, amplitudes, Constant index) and radiological (acromio-epiphyseal distance) evaluation at a mean follow up of 13.6 months.

RESULTS

Outcomes concerning pain, quality of life and Constant index were good and similar to other series. Few complications were observed. An increase of the acromio-epiphyseal distance of 33 to 50% compared to the non operated side is associated with a good functional result.

CONCLUSION

Our results confirm those of other series and show that Delta 3 inverted prosthesis is an efficient therapeutic alternative in arthropathy with rotator cuff tears. Rehabilitation is fairly short and easy. The increase of the acromio-epiphyseal distance determines the tension of the deltoid muscle and could predict a favorable outcome.

Mutations in the fukutin-related protein gene (FKRP) identify limb girdle muscular dystrophy 2I as a milder allelic variant of congenital muscular dystrophy MDC1C

The limb girdle and congenital muscular dystrophies (LGMD and CMD) are characterized by skeletal muscle weakness and dystrophic muscle changes. The onset of symptoms in CMD is within the first few months of life, whereas in LGMD they can occur in late childhood, adolescence or adult life. We have recently demonstrated that the fukutin-related protein gene (FKRP) is mutated in a severe form of CMD (MDC1C), characterized by the inability to walk, leg muscle hypertrophy and a secondary deficiency of laminin alpha2 and alpha-dystroglycan. Both MDC1C and LGMD2I map to an identical region on chromosome 19q13.3. To investigate whether these are allelic disorders, we undertook mutation analysis of FKRP in 25 potential LGMD2I families, including some with a severe and early onset phenotype. Mutations were identified in individuals from 17 families. A variable reduction of alpha-dystroglycan expression was observed in the skeletal muscle biopsy of all individuals studied. In addition, several cases showed a deficiency of laminin alpha2 either by immunocytochemistry or western blotting. Unexpectedly, affected individuals from 15 families had an identical C826A (Leu276Ileu) mutation, including five that were homozygous for this change. Linkage analysis identified at least two possible haplotypes in linkage disequilibrium with this mutation. Patients with the C826A change had the clinically less severe LGMD2I phenotype, suggesting that this is a less disruptive FKRP mutation than those found in MDC1C. The spectrum of LGMD2I phenotypes ranged from infants with an early presentation and a Duchenne-like disease course including cardiomyopathy, to milder phenotypes compatible with a favourable long-term outcome.

Genomic organization of the dysferlin gene and novel mutations in Miyoshi myopathy

OBJECTIVE

Mutations in the skeletal muscle gene dysferlin cause two autosomal recessive forms of muscular dystrophy: Miyoshi myopathy (MM) and limb girdle muscular dystrophy type 2B (LGMD2B). The purpose of this study was to define the genomic organization of the dysferlin gene and conduct mutational screening and a survey of clinical features in 21 patients with defined molecular defects in the dysferlin gene.

METHODS

Genomic organization of the gene was determined by comparing the dysferlin cDNA and genomic sequence in P1-derived artificial chromosomes (PACs) containing the gene. Mutational screening entailed conformational analysis and sequencing of genomic DNA and cDNA. Clinical records of patients with defined dysferlin gene defects were reviewed retrospectively.

RESULTS

The dysferlin gene encompasses 55 exons spanning over 150 kb of genomic DNA. Mutational screening revealed nine novel mutations associated with MM. The range of onset in this patient group was narrow with a mean of 19.0 +/- 3.9 years.

CONCLUSION

This study confirms that the dysferlin gene is mutated in MM and LGMD2B and extends understanding of the timing of onset of the disease. Knowledge of the genomic organization of the gene will facilitate mutation detection and investigations of the molecular biologic properties of the dysferlin gene.

Pathophysiology of limb girdle muscular dystrophy type 2A: hypothesis and new insights into the IkappaBalpha/NF-kappaB survival pathway in skeletal muscle

Limb girdle muscular dystrophies (LGMDs) are a group of clinically heterogeneous genetic diseases characterized by progressive weakness and atrophy of scapular and pelvic muscles, with either a dominant or recessive autosomic mode of inheritance. The first symptoms of the disorder appear during the first 20 years of life and progresses gradually, and a walking disability develops 10-20 years later. The gene responsible for LGMD2A has been identified and encodes calpain 3, a protease expressed mainly in skeletal muscle. Apoptotic myonuclei were recently detected in muscular biopsy specimens of LGMD2A patients, and apoptosis was found to be correlated with altered subcellular distribution of inhibitory protein kappaBalpha (IkappaBalpha) and nuclear factor kappaB (NF-kappaB), resulting in sarcoplasmic sequestration of NF-kappaB. Calpain 3 dependent IkappaBalpha degradation was reconstituted in vitro, supporting a possible in vivo sequence of events leading from calpain 3 deficiency to IkappaBkappa accumulation, prevention of nuclear translocation of NF-kappaB, and ultimately apoptosis. Therefore calpain 3, present in healthy muscle as sarcoplasmic and nuclear forms, may control IkappaBalpha turnover and indirectly regulate NF-kappaB dependent expression of survival genes. Recent data reported from a new model of LGMD2A in mice and from other muscular disorders strengthen understanding of the molecular links between calpain 3 and the Ikappaalpha/NF-kappaB pathway. Finally, in light of the lack of apoptosis observed in inflammatory myopathies, a unifying model for the control of cell survival in muscle is proposed and discussed

Calpain 3 mRNA expression in mice after denervation and during muscle regeneration

Lack of functional calpain 3 in humans is a cause of limb girdle muscular dystrophy, but the function(s) of calpain 3 remain(s) unknown. Special muscle conditions in which calpain 3 is downregulated could yield valuable clues to the understanding of its function(s). We monitored calpain 3 mRNA amounts by quantitative RT-PCR and compared them with those of α-skeletal actin mRNA in mouse leg muscles for different types of denervation and muscle injury. Intact muscle denervation reduced calpain 3 mRNA expression by a factor of 5 to 10, while α-skeletal actin mRNA was reduced in a slower and less extensive manner. Muscle injury (denervation-devascularization), which leads to muscle degeneration and regeneration, induced a 20-fold decrease in the mRNA level of both calpain 3 and α-skeletal actin. Furthermore, whereas in normal muscle and intact denervated muscle, the full-length transcript is the major calpain 3 mRNA, in injured muscle, isoforms lacking exon 6 are predominant during the early regeneration process. These data suggest that muscle condition determines the specific calpain 3 isoform pattern of expression and that calpain 3 expression is downregulated by denervation.

Secondary calpain3 deficiency in 2q-linked muscular dystrophy: titin is the candidate gene

BACKGROUND

Tibial muscular dystrophy (TMD), a late-onset dominant distal myopathy, is caused by yet unknown mutations on chromosome 2q, whereas MD with myositis (MDM) is a muscular dystrophy of the mouse, also progressing with age and linked to mouse chromosome 2. For both disorders, linkage studies have implicated titin as a potential candidate gene.

METHODS

The authors analyzed major candidate regions in the titin gene by sequencing and Southern blot hybridization, and performed titin immunohistochemistry on TMD patient material to identify the underlying mutation. Western blot studies were performed on the known titin ligands in muscle samples of both disorders and controls, and analysis of apoptosis was also performed.

RESULTS

The authors identified almost complete loss of calpain3, a ligand of titin, in the patient with limb-girdle MD (LGMD) with a homozygous state of TMD haplotype when primary calpain3 gene defect was excluded. Apoptotic myonuclei with altered distribution of transcription factor NF-kB and its inhibitor IkBalpha were encountered in muscle samples of patients with either heterozygous or homozygous TMD haplotype. Similar findings were confirmed in the MDM mouse.

CONCLUSIONS

These results imply that titin mutations may be responsible for TMD, and that the pathophysiologic pathway following calpain3 deficiency may overlap with LGMD2A. The loss of calpain3 could be a downstream effect of the deficient TMD gene product. The significance of the secondary calpain3 defect for the pathogenesis of TMD was emphasized by similar calpain3 deficiency in the MDM mouse, which is suggested to be a mouse model for TMD. Homozygous mutation at the 2q locus may thus be capable of producing yet another LGMD.