Restoration of dystrophin expression in cultured hybrid myotubes

Absence of dystrophin, as found in Duchenne boys, mdx mice and HFMD cats, leads to destabilization of the sarcolemmal-associated protein complex. Gene and cell therapy strategies aim to restore the dystrophin-associated protein complex. In order to better understand the cellular events involved in such therapy in feline and human muscular dystrophy, we asked whether dystrophin-deficient myoblasts would fuse with myoblasts expressing normal dystrophin, and whether the complex would be restored after such a fusion. Cat and human myoblasts were isolated from skeletal muscle of normal subjects and of patients with dystrophin deficiency and proliferated well. After co-culture with normal myoblasts, they fused to form hybrid myotubes. These hybrid myotubes expressed dystrophin, utrophin and dystrophin- associated proteins. Expression of these proteins were restored also in the vicinity of nuclei from dystrophin-deficient donors. These results demonstrate that dystrophin can be expressed and handled normally by hybrid myotubes. They show that myoblasts with a normal dystrophin gene can restore dystrophin expression in dystrophin-deficient myoblasts.

Disturbed trafficking of dystrophin and associated proteins in targetoid phenomena after chronic muscle denervation

Dystrophin and associated proteins form a complex with an important role at the sarcolemma. Expression of this protein complex is highly regulated during development and regeneration. In order to better understand assembling patterns of these proteins, we have studied their expression in targetoid-like phenomena found in human muscle after chronic denervation, a situation known to give rise to abnormal protein trafficking. In eight biopsies of patients with chronic denervation, mainly resulting from amyotrophic lateral sclerosis, we found a number of targetoid phenomena. Selective accumulation of a number of sarcolemmal and sarcoplasmatic proteins occurred in targetoid phenomena. The larger majority of them contained gamma-sarcoglycan (gammaSG), but none contained the developmental heavy chain myosin isoform. In a series of 166 targetoid phenomena which could be studied with 17 different antibodies recognizing sarcolemmal and cytoplasmatic proteins, a high level of colocalization of gammaSG with desmin and alpha-actinin was found. Colocalization rate was much lower with other proteins, including other members of the dystrophin-associated protein complex. These data show that selective changes in expression of otherwise closely related proteins occur during disturbed trafficking leading to target formation. Because members of the dystrophin-associated protein complex do not accumulate in a similar fashion within targets, we suggest that a complex molecular control of gene expression and trafficking of this complex is involved after chronic muscle denervation.

Multiple independent molecular etiology for limb-girdle muscular dystrophy type 2A patients from various geographical origins

Limb-girdle muscular dystrophies (LGMDs) are a group of neuromuscular diseases presenting great clinical heterogeneity. Mutations in CANP3, the gene encoding muscle-specific calpain, were used to identify this gene as the genetic site responsible for autosomal recessive LGMD type 2A (LGMD2A; MIM 253600). Analyses of the segregation of markers flanking the LGMD2A locus and a search for CANP3 mutations were performed for 21 LGMD2 pedigrees from various origins. In addition to the 16 mutations described previously, we report 19 novel mutations. These data indicate that muscular dystrophy caused by mutations in CANP3 are found in patients from all countries examined so far and further support the wide heterogeneity of molecular defects in this rare disease.

[Parkinson syndrome: iatrogenic causes, iatrogenic treatment results]

Iatrogenically induced problems are well known in the treatment of Parkinson's disease. Too rapid introduction or changes in dosage of dopamine agonists and levodopa may lead to acute side effects. Wrong dosage of these drugs in the treatment of advanced Parkinson's disease can lead to severe dyskinesia. All other drugs used in the treatment of Parkinson's disease also have a side effect profile which must be known to the treating physician. In addition, iatrogenic problems may also be found in the general management of the patient and his family. It is also well known that a parkinsonian syndrome may be induced by several types of drugs.

Becker muscular dystrophy with marked divergence between clinical and molecular genetic findings: case series

Both Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) are caused by mutations of the X-linked dystrophin gene. BMD patients are less affected clinically than DMD patients. We present five patients with a diagnosis of BMD. First, two identical twins, with a deletion of exon 48 of the dystrophin gene, who experienced prominent muscle cramps from the age of three. The histopathological examination of muscle biopsies of these two twins revealed only very slight muscle fiber alterations. Second, two brothers who displayed marked, unusual intrafamilial variability of the clinical picture as well as showing a new point mutation in the dystrophin gene. And finally, a fifth boy who displayed a new point mutation in the dystrophin gene. Although he was clinically asymptomatic at the age of 15 and muscle biopsy only showed very minor myopathic signs, serum Creatine Kinase (CK) levels had been considerably elevated for years. Taken together, these cases add to the spectrum of marked discrepancies in clinical, histopathological and molecular genetic findings in BMD.

Liver injury due to verapamil

A 56-year-old female patient on verapamil for hypertension experienced two episodes of jaundice, pruritus and upper abdominal pain with transaminase elevated up to six-fold and alkaline phosphatase up to four-fold when inadvertently re-challenged with the drug. Liver biopsy showed marked cholestasis. Verapamil can occasionally cause mixed cytotoxic-cholestatic liver injury.

[Clinical and molecular genetic analysis of 4 Swiss families with the pure form of hereditary spastic spinal paralysis]

Hereditary spastic paraplegia (HSP) is a rare neurodegenerative disease of the spinal cord with a progressive gait disorder, associated with other neurological abnormalities in the complicated form. A cluster of families with this disorder in the central part of the country has long been known to Swiss neurologists. In the present report, we describe our clinical and molecular findings in four large families originating from this region and suffering from a pure HSP form. Clinical presentation was similar in the four families. The age of onset varied widely from 2 to 70 years with the appearance of a gait disorder, which slowly progressed to wheelchair confinement after 30-70 years. No other neurological abnormality was found except for impairment of the vibration sense and sphincter abnormalities. In three families an association with markers of the SPG4 locus on chromosome 2 was found. In the fourth, the largest one, no linkage could be found with either SPG4, or with the other two known loci, SPG3 on chromosome 14 and SPG6 on chromosome 15. These data demonstrate the genetic heterogeneity in HSP, even in families from the same region. They also suggest the presence of at least one additional locus for the pure form.

Neurons with neurokinin B mRNA in the rat magnocellular basal nucleus: distribution, projection and colocalization studies

Mapping and cortical projections of neurons containing neurokinin B (NKB) mRNA in the rat basal forebrain were studied using hybridization histochemistry and retrograde labeling. Neurokinin B mRNA was found in a small proportion of the neurons present in the magnocellular basal nucleus that project to the cortex. Most of these neurons projected to the frontal and parietal cortices, whereas only few projected to the occipital cortex and almost none to allocortical areas, including the olfactory bulb. NKB mRNA colocalization with galanin or substance P mRNAs, both found within neurons of the magnocellular basal nucleus, was not detected there. These results demonstrate a novel diffuse neocortical tachykinin input from the basal forebrain, in addition to the well-known cholinergic one.

[Quadriceps myopathy as dystrophin-associated myopathy]

Duchenne and Becker muscular dystrophy are both caused by a deletion in the dystrophin gene. In the past few years, many reports of atypical myopathies have been published where an association with a deletion within the same gene was found. We report one sporadic and one familial case of myopathy where we were able to demonstrate a deletion of the dystrophin locus using DNA analysis.

[Molecular genetic investigations in muscular diseases]

The last couple of years have witnessed a rapid development in discoveries of the genetic background in myopathies. It is therefore timely to review the impact they have on clinical work. The recognition of a myopathy remains a clinical activity, and biopsy retains a major role. Molecular genetic investigation can be contemplated early in cases with certain typical clinical presentation. In others, the correct indication to such an investigation can only be made based on findings at biopsy. The information of precise mutation can be used for genetic counselling of the family. Knowledge of genes, whose mutations are sufficient to cause certain myopathies, have provided a great amount of knowledge about pathophysiological mechanisms involved. Some are arguably rare diseases, however, this knowledge also helps understand more frequent myopathies, as it has been the case in neurodegenerative disorders.

Increased energy cost of walking in multiple sclerosis: effect of spasticity, ataxia, and weakness

Multiple sclerosis patients with motor involvement of the lower extremities and the trunk often experience exertional dyspnea and generalized or leg fatigue on walking, and their walking performance is reduced. It has recently been suggested that a high energy cost of walking (Cw) may be an important contributing factor to the observed dyspnea and fatigue. The purpose of this study was to determine which factors influence Cw. Clinical tests were used to assess the major alterations of the motor system. Thirty-three patients (mean age 41 years, mean maximal speed 2.8 km/h, range 1.2 to 6.2 km/h) in a stable phase of their disease were examined. Cost of walking (mean +/- SE) at 1.8 km/h was 0.287 +/- 0.018 ml 02.kg-1.m-1 (normal value 0.163 +/- 0.007, p less than 0.001). A multivariate regression analysis showed that Cw was significantly related to spasticity of the lower extremities, whereas lower extremity and truncal weakness did not contribute to the observed high Cw.

[Chemical neuro-anatomy of the thalamus: an example of the co-expression of 2 neuropeptides, cholecystokinin and intestinal vasoactive peptide]

Recent studies using hybridization histochemistry have demonstrated the presence of cholecystokinin (CCK) gene expression in thalamocortical and thalamo-striatal neurons. To further understand the chemical anatomy of the thalamus, we used the same method to study the coexpression of CCK and vasoactive intestinal peptide (VIP) genes in the same neurons. Most of the neurons expressing the VIP gene in the rat dorsal thalamus (found especially in the ventrolateral nucleus) also expressed the CCK gene, as demonstrated by autoradiography on emulsion-coated adjacent sections studied with probes recognizing either mRNA. Some further neurons, located in the reticular nucleus, had VIP mRNA at lower levels of expression but did not appear to contain CCK mRNA.

[Treatment of movement disorders using botulinum toxin]

Intramuscular injections of botulinum toxin (Botox) are followed by a dose-dependent focal paresis which can be used to treat several focal movement disorders. Botox injections are recommended as effective for the treatment of blepharospasm, hemifacial spasm, and cervical dystonia (torticollis). Focal dystonias elsewhere (for example, writer's cramp) can often be treated with similar success. Others, such as oromandibular dystonia, are more difficult to treat. In the case of more generalized dystonias, some focal muscle spasms can be treated with success by local intramuscular injections. New indications are still being investigated, for example in focal tremors and spasticity. Side effects are in general slight and disappear at the end of toxin effect. In general, it is necessary to repeat the injections after a couple of months, due to a cessation of effect after regrowth of nerve terminals. New injections have similar effects even over years of treatment.

Screening of GABAA-receptor gene mutations in primary dystonia

Several lines of evidence suggest that GABA-ergic neurotransmission plays a role in the pathogenesis of primary dystonia in humans. In this study, we tested the hypothesis that mutations in the GABRA1, GABRB3, and GABRG2 genes encoding the alpha1, beta3, and gamma subunits of the GABA(A) receptor are involved in familial primary dystonia. All exons and exon-intron boundaries of the above genes were amplified by PCR from genomic DNA in 28 patients who had primary dystonia and a positive family history but had no mutation in any other genes known to be involved in primary dystonia. The PCR products were analyzed by single strand conformation polymorphism followed by sequencing of variant conformers compared with normal controls (n = 54). We found no mutations in these genes. We did, however, find a new polymorphism, 559 + 80G>A in intron 5 of GABRA1, and we also confirmed several that were previously reported, including 315C>T in exon 3 and 588C>T in exon 5 of GABRG2, but there were no significant differences between controls and patients in the allele and genotype frequencies of these polymorphisms. In conclusion, mutations of GABRA1, GABRB3, and GABRG2 appear not to play a major role in the development of familial primary dystonia.

[New advances in muscular dystrophy: an up-to-date diagnostic plan]

During the last few years new findings from molecular studies have much advanced the understanding of muscular dystrophies. A unifying concept has been put forward to explain many forms of such disorders. A complex of several proteins associated to dystrophin has been described which links the cytoskeleton to the extracellular matrix. The components of this complex can be examined at molecular and protein levels. This allows a search for an exact diagnosis in many such patients. Relevant new facts are reviewed in the frame of a traditional approach to the diagnosis of muscular dystrophies.

[Idiopathic myositis]

The idiopathic myositis, dermatomyositis, polymyositis and inclusion body myositis are recognized by their clinical and laboratory presentation, and by morphological changes in the muscle biopsy. A rapid diagnostic process is important, in order to start early treatment, which will be more effective and to direct further investigations and management. In the presence of dermatomyositis a precise investigation of neoplasia is important because they are often associated, which is not the case with inclusion body myositis. Symptoms in dermatomyositis and polymyositis respond sometimes quite well to immunomodulatory therapy but not in inclusion myositis. Controlled muscle training may sometimes slow progression in inclusion myositis.