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ObjectiveTo identify the rate of change of clinical outcome measures in children with 2 types of congenital muscular dystrophy (CMD), COL6-related dystrophies (COL6-RDs) and LAMA2-related dystrophies (LAMA2-RDs).MethodsOver the course of 4 years, 47 individuals (23 with COL6-RD and 24 with LAMA2-RD) 4 to 22 years of age were evaluated. Assessments included the Motor Function Measure 32 (MFM32), myometry (knee flexors and extensors, elbow flexors and extensors), goniometry (knee and elbow extension), pulmonary function tests, and quality-of-life measures. Separate linear mixed-effects models were fitted for each outcome measurement, with subject-specific random intercepts.ResultsTotal MFM32 scores for COL6-RDs and LAMA2-RDs decreased at a rate of 4.01 and 2.60 points, respectively, each year (p < 0.01). All muscle groups except elbow flexors for individuals with COL6-RDs decreased in strength between 1.70% (p < 0.05) and 2.55% (p < 0.01). Range-of-motion measurements decreased by 3.21° (p < 0.05) at the left elbow each year in individuals with LAMA2-RDs and 2.35° (p < 0.01) in right knee extension each year in individuals with COL6-RDs. Pulmonary function demonstrated a yearly decline in sitting forced vital capacity percent predicted of 3.03% (p < 0.01) in individuals with COL6-RDs. There was no significant change in quality-of-life measures analyzed.ConclusionResults of this study describe the rate of change of motor function as measured by the MFM32, muscle strength, range of motion, and pulmonary function in individuals with COL6-RDs and LAMA2-RDs.

A 26-year-old right-handed man presented with progressive gait imbalance over 6 years. His examination was consistent with cerebellar and upper motor neuronal dysfunction. He had no significant family history. Most of the serum and cerebrospinal fluid studies were unremarkable. Neuroimaging was remarkable for mild cerebellar and noticeable thoracic spinal cord atrophy. The initial differential diagnosis for the patient's presentation was broad, but because of certain clinical characteristics, it was later focused on hereditary ataxias. Detailed analysis of the clinical features in the history, neurologic examination, and neuroimaging studies led to the diagnosis.

Familial ALS patients with TDP-43 gene mutations and sporadic ALS patients share common TDP-43 neuronal pathology. To delineate mechanisms underlying TDP-43 proteinopathies, transgenic mice expressing A315T, M337V or wild type human TDP-43 were generated. Multiple TDP-43 founders developed a severe early motor phenotype that correlated with TDP-43 levels in spinal cord. Three A315T TDP-43 lines developed later onset paralysis with cytoplasmic ubiquitin inclusions, gliosis and TDP-43 redistribution and fragmentation. The WT TDP-43 mouse line with highest spinal cord expression levels remains asymptomatic, although these mice show spinal cord pathology. One WT TDP-43 line with high skeletal muscle levels of TDP-43 developed a severe progressive myopathy. Over-expression of TDP-43 in vivo is sufficient to produce progressive motor phenotypes by a toxic gain of function paradigm. Transgenic mouse lines expressing untagged mutant and wild type TDP-43 under the same promoter represent a powerful new model system for studying TDP-43 proteinopathies in vivo.

International audience; G93A SOD1 transgenic mice overexpressing CCS protein develop an accelerated disease course that is associated with enhanced mitochondrial pathology and increased mitochondrial localization of mutant SOD1. Because these results suggest an effect of mutant SOD1 on mitochondrial function, we assessed the enzymatic activities of mitochondrial respiratory chain complexes in the spinal cords of CCS/G93A SOD1 and control mice. CCS/G93A SOD1 mouse spinal cord demonstrates a 55% loss of complex IV (cytochrome c oxidase) activity compared with spinal cord from age-matched non-transgenic or G93A SOD1 mice. In contrast, CCS/G93A SOD1 spinal cord shows no reduction in the activities of complex I, II, or III. Blue native gel analysis further demonstrates a marked reduction in the levels of complex IV but not of complex I, II, III, or V in spinal cords of CCS/G93A SOD1 mice compared with non-transgenic, G93A SOD1, or CCS/WT SOD1 controls. With SDS-PAGE analysis, spinal cords from CCS/G93A SOD1 mice showed significant decreases in the levels of two structural subunits of cytochrome c oxidase, COX1 and COX5b, relative to controls. In contrast, CCS/G93A SOD1 mouse spinal cord showed no reduction in levels of selected subunits from complexes I, II, III, or V. Heme A analyses of spinal cord further support the existence of cytochrome c oxidase deficiency in CCS/G93A SOD1 mice. Collectively, these results establish that CCS/G93A SOD1 mice manifest an isolated complex IV deficiency which may underlie a substantial part of mutant SOD1-induced mitochondrial cytopathy.

The CCS copper chaperone is critical for maturation of Cu, Zn-superoxide dismutase (SOD1) through insertion of the copper co-factor and oxidization of an intra-subunit disulfide. The disulfide helps stabilize the SOD1 polypeptide, which can be particularly important in cases of amyotrophic lateral sclerosis (ALS) linked to misfolding of mutant SOD1. Surprisingly, however, over-expressed CCS was recently shown to greatly accelerate disease in a G93A SOD1 mouse model for ALS. Herein we show that disease in these G93A/CCS mice correlates with incomplete oxidation of the SOD1 disulfide. In the brain and spinal cord, CCS over-expression failed to enhance oxidation of the G93A SOD1 disulfide and if anything, effected some accumulation of disulfide-reduced SOD1. This effect was mirrored in culture with a C244,246S mutant of CCS that has the capacity to interact with SOD1 but can neither insert copper nor oxidize the disulfide. In spite of disulfide effects, there was no evidence for increased SOD1 aggregation. If anything, CCS over-expression prevented SOD1 misfolding in culture as monitored by detergent insolubility. This protection against SOD1 misfolding does not require SOD1 enzyme activation as the same effect was obtained with the C244,246S allele of CCS. In the G93A SOD1 mouse, CCS over-expression was likewise associated with a lack of obvious SOD1 misfolding marked by detergent insolubility. CCS over-expression accelerates SOD1-linked disease without the hallmarks of misfolding and aggregation seen in other mutant SOD1 models. These studies are the first to indicate biological effects of CCS in the absence of SOD1 enzymatic activation.

The accumulation of protein aggregates is thought to be an important component in the pathogenesis of mutant SOD1-induced disease. Mutant SOD1 aggregates appear to be cleared by proteasomes, at least in vitro, suggesting a potentially important role for proteasome degradation pathways in vivo. G93A SOD1 transgenic mice show an increase in proteasome activity and induction of immuno-proteasome subunits within spinal cord as they develop neurological symptoms. To determine what role immuno-proteasomes may have in mutant SOD1-induced disease, we crossed G93A SOD1 transgenic mice with LMP2-/- mice to obtain G93A SOD1 mice lacking the LMP2 immuno-proteasome subunit. G93A SOD1/LMP2-/- mice show significant reductions in proteasome function within spinal cord compared to G93A SOD1 mice. However, G93A SOD1/LMP2-/- mice show no change in motor function decline, or survival compared to G93A SOD1 mice. These results indicate that the loss of immuno-proteasome function in vivo does not significantly alter mutant SOD1-induced disease.

Mutations in SOD1 cause FALS by a gain of function likely related to protein misfolding and aggregation. SOD1 mutations encompass virtually every domain of the molecule, making it difficult to identify motifs important in SOD1 aggregation. Zinc binding to SOD1 is important for structural integrity, and is hypothesized to play a role in mutant SOD1 aggregation. To address this question, we mutated the unique zinc binding sites of SOD1 and examined whether these changes would influence SOD1 aggregation. We generated single and multiple mutations in SOD1 zinc binding residues (H71, H80 and D83) either alone or in combination with an aggregate forming mutation (A4V) known to cause disease. These SOD1 mutants were assayed for their ability to form aggregates. Using an in vitro cellular SOD1 aggregation assay, we show that combining A4V with mutations in non-zinc binding domains (G37R or G85R) increases SOD1 aggregation potential. Mutations at two zinc binding residues (H71G and D83G) also increase SOD1 aggregation potential. However, an H80G mutation at the third zinc binding residue decreases SOD1 aggregation potential even in the context of other aggregate forming SOD1 mutations. These results demonstrate that various mutations have different effects on SOD1 aggregation potential and that the H80G mutation appears to uniquely act as a dominant inhibitor of SOD1 aggregation.

(2004). Western ALS Study Group. Amyotrophic Lateral Sclerosis and Other Motor Neuron Disorders: Vol. 5, No. sup1, pp. 121-124.

Aggregation of Cu,Zn superoxide dismutase (SOD1) protein is a pathologic hallmark of familial amyotrophic lateral sclerosis linked to mutations in the SOD1 gene, although the structural motifs within mutant SOD1 that are responsible for its aggregation are unknown. Copper chaperone for SOD1 (CCS) and extracellular Cu,Zn superoxide dismutase (SOD3) have some sequence identity with SOD1, particularly in the regions of metal binding, but play no significant role in mutant SOD1-induced disease. We hypothesized that it would be possible to form CCS- or SOD3-positive aggregates by making these molecules resemble mutant SOD1 via the introduction of point mutations in codons homologous to a disease causing G85R SOD1 mutation. Using an in vitro assay system, we found that expression of wild type human CCS or a modified intracellular wild type SOD3 does not result in significant aggregate formation. In contrast, expression of G168R CCS or G146R SOD3 produced aggregates as evidenced by the presence of high molecular weight protein complexes on Western gels or inclusion bodies on immunofluorescence. CCS- and SOD3-positive inclusions appear to be ubiquitinated and localized to aggresomes. These results suggest that proteins sharing structural similarities to mutant SOD1 are also at risk for aggregate formation.

Background: Regulation of microRNA activity independent of processing and biogenesis has not been demonstrated. Results: The RNA-binding protein, TDP-43, interacts with mature miR-1/miR-206, limiting their RNA-induced silencing complex (RISC) association and activity. Conclusion: RNA-binding proteins can selectively control microRNA activity by disrupting RISC incorporation. Significance: This is the first known microRNA-protein interaction that controls microRNA activity independent of processing., MicroRNA (miRNA) maturation is regulated by interaction of particular miRNA precursors with specific RNA-binding proteins. Following their biogenesis, mature miRNAs are incorporated into the RNA-induced silencing complex (RISC) where they interact with mRNAs to negatively regulate protein production. However, little is known about how mature miRNAs are regulated at the level of their activity. To address this, we screened for proteins differentially bound to the mature form of the miR-1 or miR-133 miRNA families. These muscle-enriched, co-transcribed miRNA pairs cooperate to suppress smooth muscle gene expression in the heart. However, they also have opposing roles, with the miR-1 family, composed of miR-1 and miR-206, promoting myogenic differentiation, whereas miR-133 maintains the progenitor state. Here, we describe a physical interaction between TDP-43, an RNA-binding protein that forms aggregates in the neuromuscular disease, amyotrophic lateral sclerosis, and the miR-1, but not miR-133, family. Deficiency of the TDP-43 Drosophila ortholog enhanced dmiR-1 activity in vivo. In mammalian cells, TDP-43 limited the activity of both miR-1 and miR-206, but not the miR-133 family, by disrupting their RISC association. Consistent with TDP-43 dampening miR-1/206 activity, protein levels of the miR-1/206 targets, IGF-1 and HDAC4, were elevated in TDP-43 transgenic mouse muscle. This occurred without corresponding Igf-1 or Hdac4 mRNA increases and despite higher miR-1 and miR-206 expression. Our findings reveal that TDP-43 negatively regulates the activity of the miR-1 family of miRNAs by limiting their bioavailability for RISC loading and suggest a processing-independent mechanism for differential regulation of miRNA activity.

1. Missense mutations in the gene encoding Cu,Zn superoxide dismutase (SOD1) are responsible for causing one form of familial amyotrophic lateral sclerosis (FALS) linked to chromosome 21q. 2. Mutant SOD1-induced disease is clearly related to a toxic gain of function for the abnormal enzyme, and recent work has begun to investigate the mechanisms underlying this toxicity. In addition to its well known and likely beneficial dismutase activity, wild type SOD1 also possesses the ability to participate in other enzymatic reactions that may be injurious to cells including peroxidation or nitration. 3. Many of the SOD1 mutations associated with FALS appear to increase the likelihood that the enzyme will perform either one of those potentially harmful functions resulting in increased hydroxyl radical formation or the addition of nitro groups to tyrosine residues within cellular proteins. 4. Because several in vitro experiments have suggested that the extent of SOD1s ability to perform peroxidase and nitration reactions is dependent on the degree of copper and or zinc binding within the enzyme, these metals have become a focus of interest for understanding the exact mechanisms underlying motor neuron dysfunction in FALS as

Objective: To ascertain the specificity of alternatively spliced mRNA variants of the astroglial glutamate transporter EAAT2 for ALS. Background: An important hypothesis for ALS pathogenesis is that motor neuron injury may result from chronically elevated glutamate levels in the CNS. Supporting this idea are reports of decreased glutamate transport in ALS. This in turn has recently been suggested to be due to the presence of aberrant mRNA splice variants for EAAT2 in ALS. Methods: Postmortem human brain tissue was obtained from different brain regions of patients with ALS, normal controls (NC), and patients with AD and Lewy body dementia (LB)—neurodegenerative diseases in which motor neurons are unaffected. Brain RNA was analyzed for EAAT2 isoforms using reverse transcription PCR and cDNA cloning/sequencing methods. Results: Splice variants lacking exons 7 or 9 were present in ALS brain, as previously reported, but were also present in brains from NC, AD, and LB patients. PCR product sequence analyses from non-ALS brain show variant splicing identical to that reported for ALS. Quantitative PCR analysis shows that these isoforms may be somewhat more abundant in ALS than AD, LB, and NC brains. Conclusions: EAAT2 mRNA splice variants are found in the brains of NC and AD patients, as in ALS. The authors cannot exclude the possibility that quantitative changes in variant EAAT2 isoforms might relate directly, or indirectly, to ALS pathology. However, the qualitative presence of these “abnormal” EAAT2 splice variants does not appear to be sufficient to explain motor neuron degeneration in ALS.

Missense mutations in the gene encoding copper zinc superoxide dismutase (SOD1) have been found to cause one form of familial amyotrophic lateral sclerosis (FALS). Although the exact mechanism of disease is unknown, abnormalities in the ability of mutant SOD1 to bind zinc or copper ions may be crucial in the pathogenesis of disease. Because members of the metallothionein (MT) family of zinc and copper binding proteins function as important cellular regulators of metal ion bioavailability in the central nervous system, we used in situ hybridization and immunohistochemistry to study the expression pattern of these molecules in a transgenic mouse model of familial ALS. In adult wild-type mouse spinal cord, expression of MT-I and MT-II is restricted to ependymal cells and a subset of astrocytes located in white matter tracts, while MT-III synthesis is limited to neurons within gray matter. Compared to wild-type littermates, transgenic mice carrying the G93A SOD1 mutation demonstrate markedly increased expression of MT-I and MT-II within astrocytes in both white and gray matter as weakness develops. MT-III synthesis in neurons is also greatly upregulated as G93A SOD1 animals age, with glial cell expression of MT-III evident by later stages of the disease. Changes in MT expression occur before the onset of motor deficits or significant motor neuron pathology in G93A SOD1 mice and remarkably extend beyond ventral horn populations of neurons and glia. These results are consistent with the hypothesis that metallothioneins may serve an early and important protective function in FALS.

Evidence garnered from both human autopsy studies and genetic animal models has suggested a potential role for astrocytes in the pathogenesis of amyotrophic lateral sclerosis (ALS). Currently, mutations in the gene encoding Cu/Zn superoxide dismutase (SOD1) represent the only known cause of motoneuron loss in the disease, producing 21q linked familial ALS (FALS). To determine whether astrocytic dysfunction has a primary role in familial ALS, we have generated multiple lines of transgenic mice expressing G86R mutant SOD1 restricted to astrocytes. In GFAP-m SOD1 mice, astrocytes exhibit significant hypertrophy and increased GFAP reactivity as the animals mature. However, GFAP-mutant SOD1 transgenic mice develop normally and do not experience spontaneous motor deficits with increasing age. Histological examination of spinal cord in aged GFAP-mSOD1 mice reveals normal motoneuron and microglial morphology. These results indicate that 21q linked FALS is not a primary disorder of astrocytes, and that expression of mutant SOD1 restricted to astrocytes is not sufficient to cause motoneuron degenerationin vivo. Expression of mutant SOD1 in other cell types, most likely neurons, is critical for the initiation of disease.

Axonal forms of autosomal dominant hereditary motor and sensory neuropathies (HMSNs) represent a heterogeneous group of disorders based on genetic linkage studies. We recently identified one large family with axonal HMSN exhibiting linkage to chromosome 3q, designated HMSN IIB, and report here the clinical and electrodiagnostic features. We clinically evaluated 10 individuals with HMSN IIB and performed detailed electrophysiologic studies in 5 of these patients. HMSN IIB is characterized clinically by the presence of distal symmetric motor weakness and prominent sensory loss affecting the lower extremities with preserved ankle reflexes. Symptomatic age at onset is in the second or early third decade of life. Six patients with HMSN IIB had distal trophic ulcerations in the feet, leading to eventual toe amputations in four cases. Electrodiagnostic studies confirmed a distal sensorimotor axonopathy involving the lower limbs with normal motor conduction velocities. Tibial H-reflexes were preserved in HMSN IIB, despite the uniform loss of sural nerve potentials. Overall, individuals with HMSN IIB demonstrated a consistent clinical and electrodiagnostic phenotype that had no overlap with genetically unaffected family members. The identification of specific clinical and electrodiagnostic features of HMSN IIB may prove useful in the diagnosis and differentiation between various subtypes of HMSN II.

Several hypotheses have been proposed for the mechanisms underlying mutant Cu,Zn Superoxide Dismutase‐related Amyotrophic Lateral Sclerosis. These include aggregation pathology, mitochondrial dysfunctions, oxidative stress, and glutamate‐mediated excitotoxicity. Mitochondrial disease may be a primary event in neurodegeneration, contributing to oxidative stress and apoptosis, or it may be caused by other cellular processes. Mitochondrial structural abnormalities have been detected in the skeletal muscle, lymphoblast and central nervous system of Amyotrophic Lateral Sclerosis patients. The cause or even the extent of mitochondrial defects in spinal cord and brain of patients with Cu,Zn Superoxide Dismutase mutations is difficult to determine because of rapid mitochondrial deterioration in autopsy samples. The focus of this review is how abnormalities in Cu,Zn Superoxide Dismutase redox states, folding and metallation contribute to mitochondrial deficiencies, investigating the differences in mitochondrial defects observed among transgenic mice expressing various Cu,Zn Superoxide Dismutase mutations.

The identification of proteins which determine fat and lean body mass composition is critical to better understanding and treating human obesity. TDP-43 is a well-conserved RNA-binding protein known to regulate alternative splicing and recently implicated in the pathogenesis of amyotrophic lateral sclerosis (ALS). While TDP-43 knockout mice show early embryonic lethality, post-natal conditional knockout mice show weight loss, fat depletion, and rapid death, suggesting an important role for TDP-43 in regulating energy metabolism. Here we report, that over-expression of TDP-43 in transgenic mice can result in a phenotype characterized by increased fat deposition and adipocyte hypertrophy. In addition, TDP-43 over-expression in skeletal muscle results in increased steady state levels of Tbc1d1, a RAB-GTPase activating protein involved in Glucose 4 transporter (Glut4) translocation. Skeletal muscle fibers isolated from TDP-43 transgenic mice show altered Glut4 translocation in response to insulin and impaired insulin mediated glucose uptake. These results indicate that levels of TDP-43 regulate body fat composition and glucose homeostasis in vivo.

Background There have been a few case reports of motor neuron disease in association with Huntington disease (HD). Objective To describe a patient presenting with prominent fasciculations, chorea, and possible amyotrophic lateral sclerosis (ALS) in whom genetic testing revealed HD mutation. Design Case report. Setting University of Texas Southwestern Medical Center, Dallas. Patient A 69-year-old man with chorea and fasciculations. Interventions Genetic and electrophysiologic testing. Main Outcome Measures Genetic test result, electrophysiologic test result, and physical examination. Results A 69-year-old man with long-standing depression and failing memory presented with muscle twitches of 8 months' duration. He was found to have choreoathetoid movements and distal weakness on neurological examination. Electrophysiologic studies revealed evidence of motor neuron disease. Genetic test showed CAG repeat of 40 on chromosome 4, confirming the diagnosis of HD. Conclusion Motor neuron disease can rarely occur in patients with HD and could be one of its presenting features.

Elucidating the cross-talk between inflammatory and cell proliferation pathways might provide important insights into the pathogenesis of inflammation-induced cancer. Here, we show that the receptor-interacting protein 1 (RIP1)-an essential mediator of inflammation-induced nuclear factor-kappaB (NF-kappaB) activation-regulates p27(Kip1) levels and cell-cycle progression. RIP1 regulates p27(Kip1) levels by an NF-kappaB-independent signal that involves activation of the phosphatidylinositol 3-kinase (PI3K)-Akt-forkhead pathway. Mouse embryonic fibroblasts (MEFs) from RIP1-knockout mice express high levels of p27(Kip1). Reconstitution of MEFs with RIP1 downregulates p27(Kip1) levels in a PI3K-dependent manner. RIP1 regulates p27(Kip1) at the messenger RNA level by regulating the p27(Kip1) promoter through the forkhead transcription factors. RIP1 expression blocks accumulation of cells in G(1) in response to serum starvation and favours cell-cycle progression. Finally, we show that overexpression of p27(Kip1) blocks the effects of RIP1 on the cell cycle. Thus, our study provides a new insight into how components of inflammatory and immune signalling pathways regulate cell-cycle progression.

Protein aggregation is a pathologic hallmark of familial amyotrophic lateral sclerosis caused by mutations in the Cu, Zn superoxide dismutase gene. Although SOD1-positive aggregates can be cleared by proteasomes, aggregates have been hypothesized to interfere with proteasome activity, leading to a vicious cycle that further enhances aggregate accumulation. To address this issue, we measured proteasome activity in transgenic mice expressing a G93A SOD1 mutation. We find that proteasome activity is induced in the spinal cord of such mice compared to controls but is not altered in uninvolved organs such as liver or spleen. This induction within spinal cord is not related to an overall increase in the total number of proteasome subunits, as evidenced by the steady expression levels of constitutive alpha7 and beta5 subunits. In contrast, we found a marked increase of inducible beta proteasome subunits, LMP2, MECL-1 and LMP7. This induction of immunoproteasome subunits does not occur in all spinal cord cell types but appears limited to astrocytes and microglia. The induction of immunoproteasome subunits in G93A spinal cord organotypic slices treated with TNF-alpha and interferon-gamma suggest that certain cytokines may mediate such responses in vivo. Our results indicate that there is an overall increase in proteasome function in the spinal cords of G93A SOD1 mice that correlates with an induction of immunoproteasomes subunits and a shift toward immunoproteasome composition. These results suggest that increased, rather than decreased, proteasome function is a response of certain cell types to mutant SOD1-induced disease within spinal cord.

Mutations in the Cu/Zn superoxide dismutase (SOD1) gene cause one form of familial amyotrophic lateral sclerosis, a progressive disorder of motor neurons leading to weakness and death of affected individuals. Experiments using both transgenic mice expressing mutant SOD1 and SOD1 knock-out mice have demonstrated that disease is caused by a toxic gain of function and not by a loss of normal SOD1 activity. Precise mechanisms underlying mutant SOD1 toxicity are unclear but may involve abnormal interactions between zinc and SOD1. The metallothioneins (MTs) represent a family of zinc binding proteins that can function as zinc chaperones for apo-SOD1 in vitro. We hypothesized that manipulation of metallothioneins in vivo might alter the disease phenotype of transgenic mice expressing G93A SOD1 and therefore crossed this line with MT-I and MT-II or MT-III knock-out mice. G93A SOD1 mice deficient of either MT-I and MT-II or MT-III exhibited significant reductions in survival compared with G93A SOD1 mice. In addition, motor dysfunction was markedly accelerated in G93A SOD1 mice deficient in metallothioneins with regard to onset (MT-I and MT-II) or progression (MT-III). These results indicate that the disease course in G93A SOD1 mice is dependent on levels of metallothionein expression. Because MT-I and MT-II are expressed in glia whereas MT-III is found in neurons, these results also indicate that primary changes within non-neuronal cells can affect mutant SOD1-induced disease and do so in ways distinct from primary neuronal changes.

Although pronounced changes in astrocytes and microglia accompany the neuronal degeneration observed in a murine model of familial amyotrophic lateral sclerosis, the significance of non-neuronal cell contribution to the disease process remains unclear. Activated astrocytes and microglia are capable of secreting numerous cytokines, some of which may have potentially harmful effects on neuron survival. For this reason we wished to determine the expression pattern of various cytokines in the spinal cords of transgenic mice expressing a Cu–Zn superoxide dismutase mutation (Tgn G93A SOD1) by using semi-quantitative RT–PCR. Three different patterns of cytokine expression were observed in G93A SOD1 transgenic mice. For most cytokines, we were unable to detect mRNA expression in Tgn G93A SOD1 mouse spinal cords at any age, yet message was readily detected in spleen or activated splenocytes. A second pattern, typified by TNF-α, was characterized by mRNA expression prior to the onset of motor deficits and increasing until the terminal stages of the disease. For other cytokines, including TGF-β1 and M-CSF, mRNA expression was detected in young presymptomatic Tgn G93A SOD1 mice (as well as wild-type and transgenic mice expressing wild-type SOD1 (Tgn SOD1)), with upregulation later occurring only in G93A SOD1 transgenic mice. These results indicate a temporal correlation between the expression of certain cytokines and the onset of motor dysfunction in Tgn G93A SOD1 mice and suggest a potential role for these molecules in the disease.

Amyotrophic lateral sclerosis (ALS) is a chronic neurodegenerative disease characterized by the progressive loss of motor neurons, leading to profound weakness and eventual death of affected individuals. For the vast majority of patients with ALS, the etiology of the disorder is unknown, and although multiple clinical trials of various therapeutic agents have been undertaken, truly effective therapy is not currently available for the disease. The selection of treatments used in ALS clinical trials frequently has its basis in promising data obtained from experimental model systems in which the proposed agent has shown some effect in protecting motor neurons from a particular insult. The likelihood of a successful clinical outcome for a given treatment in ALS would therefore depend on two principal factors, including the similarity of the model to the disease and the biologic action of the potential therapeutic agent. Partly because early experimental models of ALS failed to replicate the disease process, treatment success in these models did not carry over into human trials. Recently, however, a variety of newer model systems have been developed and utilized to investigate motor neuron degeneration as related to ALS. For example, in this issue, Corse et al. use a rat spinal cord organotypic slice subjected to glutamate excitotoxicity as a model system to test the effectiveness of neurotrophic factors in preventing motor neuron degeneration. This review will assess the strengths and weaknesses of differing ALS model systems that have been used to preclinically test potential drug efficacy in ALS.

Objective: To describe a sporadic motor neuron disorder that remains largely restricted to the upper limbs over time. Background: Progressive amyotrophy that is isolated to the upper limbs in an adult often suggests ALS. The fact that weakness can remain largely confined to the arms for long periods of time in individuals presenting with this phenotype has not been emphasized. Methods: We reviewed the records of patients who had a neurogenic “man-in-the-barrel” phenotype documented by examination at least 18 months after onset. These patients had severe bilateral upper-extremity neurogenic atrophy that spared lower-extremity, respiratory, and bulbar musculature. Results: Nine of 10 patients meeting these criteria had a purely lower motor neuron disorder. During follow-up periods ranging from 3 to 11 years from onset, only three patients developed lower-extremity weakness, and none developed respiratory or bulbar dysfunction or lost the ability to ambulate. Conclusion: Patients presenting with severe weakness that is fully isolated to the upper limbs, without pyramidal signs, may have a relatively stable variant of motor neuron disease.

The purpose of this study was to search for STA gene defects in three families with clinically typical Emery-Dreifuss muscular dystrophy. Emery-Dreifuss is an X-linked muscular dystrophy with humeroperoneal weakness and life-threatening, but treatable, cardiac abnormalities in male patients and in female carriers. The defect is in the gene coding for emerin, a 254 amino acid protein of unknown function. Complementary and genomic DNA from T lymphocytes from the reported patients and their family members were amplified, cloned, and sequenced. A novel mutation, a 26 base-pair deletion in three brothers and a carrier mother, was detected in one family. A splicing mutation with one base pair insertion and a five base-pair deletion, which have been described previously, were found in the second and third families, respectively. The additional novel mutation detected and the findings of three different mutations in these three families support the idea of genetic heterogeneity of Emery-Dreifuss muscular dystrophy with different mutations in different families.

The last 5 years have witnessed a great outgrowth in the number of clinical trials testing neuronal growth factors as potential treatments in ALS. These attempts to prevent motor neuron degeneration in ALS with the use of growth factors have their basis in the profound abilities of these molecules to affect motor neuron survival in experimental animals during early development and into maturity. Recent advances in molecular biology have led to the identification of a large number of new potential motor neuron growth factors Table 1, as well as insights into the molecular mechanisms regulating motor neuron death after growth factor deprivation. A major challenge in the field is now to select those growth factors that are the most promising for future ALS trials either alone or in combination therapy. View this table: Table 1. Motor neuron growth factors Two members of the prototypical family of nerve growth factors, the neurotrophins, are powerful modulators of motor neuron survival during development and into adulthood. The neurotrophin family in mammals comprises four members, including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4), molecules that share a significant degree of sequence homology. [1] An early indicator that one or more members of this neurotrophin growth factor family might affect motor neurons derived from experiments performed by Yan and colleagues. [2] These investigators demonstrated that motor neurons have the ability to retrogradely transport members of the neurotrophin family, including BDNF and NT-3, after these molecules have been injected into peripheral muscle. This experiment provided evidence that motor neurons express receptors for neurotrophins and might, in fact, respond to them. Localization studies have also demonstrated that skeletal muscle normally synthesizes neurotrophins (BDNF, NT-3, and NT-4) during the period of motor neuron innervation, during the maturation of synapse formation, and into adulthood. [3,4] …

Motor neuropathies associated with electrodiagnostic evidence of motor conduction block often improve after treatment with immunotherapy, but there is less evidence about the responsiveness of lower motor neuron (LMN) syndromes without conduction block. In this study we treated four patients with an asymmetric, predominantly distal LMN syndrome associated with high serum titers of IgM anti-GM1 ganglioside antibodies but without conduction block on electrodiagnostic testing. Treatment courses consisted of five to seven repeated monthly regimens of plasma exchange on 2 consecutive days followed, on day 3, by intravenous cyclophosphamide (1 g/m2). The results of treatment were quantitatively measured using hand-held dynamometry. We found that all four patients showed progressive improvement in strength over the 6 to 24 months following treatment. Improvement was documented by both objective muscle testing and patient reports of increased strength and less fatigability. We conclude that immunotherapy may be followed by useful functional benefit in selected patients with an asymmetric, predominantly distal LMN syndrome associated with high serum titers of IgM anti-GM1 antibodies. Gradual improvement often begins as late as 6 to 9 months after the onset of treatment and may persist for 1 to 2 years, or longer, after immunosuppressive treatment is stopped.