Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0004134 (ataxia)
 15,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Analysis of the molecular defects in mouse mutants can identify candidate genes for human neurological disorders. During the past 2 years, mutations in sodium channels, calcium channels and potassium channels have been identified by positional cloning of the spontaneous mouse mutants motor endplate disease, tottering, lethargic and weaver. The phenotypes of four allelic mutations identified in the sodium channel gene Scn8a range from ataxia and muscle weakness through severe dystonia and progressive paralysis, indicating that human mutations in this gene could be associated with a variety of clinical syndromes. Mutations of the calcium channel subunits beta 4 in the lethargic mouse and alpha 1A in the tottering mouse have specific effects on cerebellar function. Targeted mutation of ligand-gated ion channels has also been used to generate new models of neurological disease. We will review these recent achievements and their implications for human neurological disease. The mouse studies indicate that mutations in ion channel genes are likely to be responsible for a broad spectrum of clinical phenotypes in human neurological disorders.
 ...
PMID:Ion channel mutations in mouse models of inherited neurological disease. 956 26

Information on the long-term development of larger series of children with non-progressive congenital ataxia (NPCA) is scarce. We have updated a personal cohort of subjects previously diagnosed as having NPCA. Children with brain malformations, acquired neurological illness, or defined syndromes were excluded. From 58 subjects, 34 were available for review (including three pairs of siblings). All our subjects had delayed motor and speech development. Truncal ataxia persisted but became less significant. Two subjects developed spasticity and three a focal dystonia. Epilepsy was a feature in 10 of the subjects. Cognitive impairment was present in 22 of 34 subjects. MRI was normal in 15 of 27. There were no obvious correlations between degree of motor delay, severity of ataxia, cognitive impairment, and neuroimaging. Although genetically and clinically not a homogeneous entity, NPCA is a helpful diagnostic label. Major problems arise in the majority of subjects related to cognitive impairment and less to neurological symptoms. Early individual prognosis is not possible from early developmental milestones, neurological signs, or neuroimaging.
 ...
PMID:Non-progressive congenital ataxia with or without cerebellar hypoplasia: a review of 34 subjects. 956 49

Niemann-Pick disease Type C (NPC) is a progressive neurovisceral metabolic disorder that is caused in most patients by a defect in a recently found gene, NPC-1. Neurological damage includes visual disorders such as vertical supranuclear gaze palsy, movement disorders such as dystonia and ataxia, dementia, and seizures. So far the biochemical deficit, most likely manifested by delayed intracellular cholesterol transport, has not been correlated with the progressive neurological damage. A mutant Balb/C mouse with a defect in the same gene is used as a model to study NPC. Pathological examination of brain tissue obtained by autopsy from NPC patients or brains of affected NPC mice of different ages, revealed signs of extensive damage throughout the brain, including neurofibrillary tangles and intracellular storage of various compounds. Loss of cerebellar Purkinje cells was the most significant specific damage. The present study examined whether the neurochemical changes present in the NPC mouse brain were related to the pathological changes. The results show major alterations in the levels of serotonin and its main metabolite, 5-hydroxyindoleacetic acid, in the cerebellum and cortex of NPC mice. The levels of the inhibitory amino acid glycine were threefold higher in the cerebellum of NPC mice and those of glutamate and GABA decreased in the cortex. Tyrosine hydroxylase immunoreactivity was present in Purkinje cells, and the levels of L-DOPA increased specifically in the vermis of the cerebellum. These results are the first to indicate changes in neurotransmitters in NPC and that these could be correlated with some of the neuropathology of this disease.
 ...
PMID:Neurochemical alterations in the cerebellum of a murine model of Niemann-Pick type C disease. 967 2

The mouse Scn8a sodium channel and its ortholog Na6 in the rat are abundantly expressed in the CNS. Mutations in mouse Scn8a result in neurological disorders, including paralysis, ataxia, and dystonia. In addition, Scn8a has been observed to mediate unique persistent and resurgent currents in cerebellar Purkinje cells (Raman et al., 1997). To examine the functional characteristics of this channel, we constructed a full-length cDNA clone encoding the mouse Scn8a sodium channel and expressed it in Xenopus oocytes. The electrophysiological properties of the Scn8a channels were compared with those of the Rat1 and Rat2 sodium channels. Scn8a channels were sensitive to tetrodotoxin at a level comparable to that of Rat1 or Rat2. Scn8a channels inactivated more rapidly and showed differences in their voltage-dependent properties compared with Rat1 and Rat2 when only the alpha subunits were expressed. Coexpression of the beta1 and beta2 subunits modulated the properties of Scn8a channels, but to a lesser extent than for the Rat1 or Rat2 channels. Therefore, all three channels showed similar voltage dependence and inactivation kinetics in the presence of the beta subunits. Scn8a channels coexpressed with the beta subunits exhibited a persistent current that became larger with increasing depolarization, which was not observed for either Rat1 or Rat2 channels. The unique persistent current observed for Scn8a channels is consistent with the hypothesis that this channel is responsible for distinct sodium conductances underlying repetitive firing of action potentials in Purkinje neurons.
 ...
PMID:Functional analysis of the mouse Scn8a sodium channel. 969 4

This paper describes a 20 year old woman with a new combination of neurological impairments in which the motor phenomena were responsive to corticosteroid treatment. She had lifelong moderate learning impairment. A variable ataxia with cerebellar characteristics was present from early life, with early severe exacerbation when seizures were uncontrolled. Atypical absence and simple and complex partial seizures were present from the first year of life and EEG abnormalities were maximal in the right parietal region, concordant with a mild non-specific abnormality of the white matter in the region of the trigone. Episodes of alternating hemiplegia occurred from 11 years, unassociated with seizures. Exercise induced dystonia occurred from the age of 5. After 10-20 minutes walking, her right foot would turn in and the right leg would stiffen, followed by the left and by falling and inability to get up for several minutes. Prednisolone improved her ataxia and was associated with cessation of both seizures and exercise induced dystonia. This adds a new syndrome to the corticosteroid responsive motor disorders associated with epilepsy.
 ...
PMID:Exercise induced steroid dependent dystonia, ataxia, and alternating hemiplegia associated with epilepsy. 970 79

Carbon disulfide toxicity is well characterized. The principal target organ is the nervous system, although cardiovascular, reproductive, ophthalmologic, and other effects are also recognized. The neurotoxicity manifests in three ways: encephalopathy, peripheral and cranial nerve dysfunction, and movement abnormalities. This report describes a case of olivopontocerebellar atrophy, a form of multiple system atrophy, developing in an adult after over 30 years of occupational exposure to carbon disulfide. The patient presented with the insidious onset of balance problems, impotence, and irritability, without tremor, cogwheel rigidity, bradykinesia, or changes in facial expression. Over the next few years severe ataxia developed, and the clinical diagnosis was confirmed with computed tomography and magnetic resonance imaging scans. The patient experienced multiple medical complications and died approximately 9 years after diagnosis. This case is consistent with a large body of clinical and experimental literature, much of it 50 years old, showing that carbon disulfide can cause movement disorders. It also serves as a reminder that movement disorders, ranging from parkinsonism to dystonia, are associated with a variety of toxic exposures such as manganese, carbon monoxide, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, and medications.
 ...
PMID:Multiple system atrophy following chronic carbon disulfide exposure. 1070 37

We studied the clinical efficacy of mexiletine, a derivative oral form of lidocaine, for treatment of spasmodic torticollis. One of the nine subjects of this study was previously reported. Before starting oral mexiletine, normal saline was first injected intravenously as placebo control; lidocaine infusion then followed and clinical evaluation was provided by dystonia rating scale scores, videotape recordings, and surface electromyographic recording. In all patients, lidocaine injection resulted in a decrease of dystonic muscle contractions within 5 minutes and the effect lasted approximately 1 hour. With gradual increase of mexiletine dose, similar clinical improvement was obtained with oral doses ranging from 450-1200 mg/day for more than 6 months. Side effects in six of nine patients included upper gastrointestinal symptoms, dizziness, ataxia, and dysarthria. These were tolerable or medically manageable; only one patient required a small reduction in mexiletine dose. Strong positive correlation was found between serum and cerebrospinal fluid (CSF) mexiletine concentrations with a CSF/serum ratio of 0.6 (r = 0.96, p = 0.0005) suggesting its effective penetrance into the central nervous system. We suggest that oral mexiletine therapy may be a safe and effective treatment for spasmodic torticollis.
 ...
PMID:Mexiletine in the treatment of spasmodic torticollis. 982 18

The voltage-gated sodium channel SCN8A is associated with inherited neurological disorders in the mouse that include ataxia, dystonia, severe muscle weakness, and paralysis. We report the complete coding sequence and exon organization of the human SCN8A gene. The predicted 1980 amino acid residues are distributed among 28 exons, including two pairs of alternatively spliced exons. The SCN8A protein is evolutionarily conserved, with 98.5% amino acid sequence identity between human and mouse. Consensus sites for phosphorylation of serine/threonine and tyrosine residues are present in cyoplasmic loop domains. The polymorphic (CA)n microsatellite marker D12S2211, with PIC = 0.68, was isolated from intron 10C of SCN8A. Single nucleotide polymorphisms in intron 19 and exon 22 were also identified. We localized SCN8A to chromosome band 12q13.1 by physical mapping on a YAC contig. The cDNA clone CSC-1 was reported by others to be a cardiac-specific sodium channel, but sequence comparison demonstrates that it is derived from exon 24 of human SCN8A. The genetic information described here will be useful in evaluating SCN8A as a candidate gene for human neurological disease.
 ...
PMID:Exon organization, coding sequence, physical mapping, and polymorphic intragenic markers for the human neuronal sodium channel gene SCN8A. 982 31

We prospectively studied motor symptoms in 32 patients with CT- or MRI-proven acute pure parietal stroke. A transient, mild, 'pseudoparesis' of the hand (90%), was noted, improved by visual attention and prompting, associated with non-awareness of muscle power (53%), transient soft pyramidal signs (50%), unilateral akinesia (100%) and motor hemineglect (37%) in non-dominant lesions. Lower motoneurone-type atrophy was not observed in this acute phase. We called 'poikilotonia' the striking unpredictable variations in muscle tone, ranging from extreme hypertonia to hypotonia, found in all patients. When maintaining postures, patients showed large oscillations (100%), laterodeviation or levitation of the arm (60%), especially in the case of large or posterior lesions, or, occasionally (3%), motor persistence or even hemicatalepsy (3%). Limb kinetic and manipulatory apraxia, with inadequate organization and anticipation of motor sequences and synergies, motor arrests, perplexity, unrecognizable gestures and loss of bimanual coordination, was a constant finding (100%). Other apraxias (62%) and difficulty in copying intransitive gestures of the hand (84%) were associated with posterior lesions involving the supramarginal gyrus. When reaching towards objects, all patients showed abnormal anticipatory hand shaping, but visuomotor ataxia (3%) was only seen with bilateral posterior stroke. Sensory (70%) or pseudocerebellar (4%) ataxia, was seen in both anterior and posterior lesions. Avoidance behaviors (34%) were not uncommon, but had no localizing value. Of the dyskinesias, hand dystonia (84%) was frequent, but athetosis (16%), asterixis (15%), postural tremor (15%), myoclonus (9%) and stereotypia (9%), were uncommon. The abnormal eye movements were unilateral hypo-akinesia of exploratory saccades (43%), abnormal ipsilateral pursuit and contralateral optokinetic nystagmus in the case of posterior lesions, and oculomotor apraxia with bilateral posterior lesions. In conclusion, parietal motor syndrome can be recognized during bedside examination, and probably reflects the loss of multiple sensory feedback to motor programs, especially those directed to the extrapersonal space.
 ...
PMID:Parietal motor syndrome: a clinical description in 32 patients in the acute phase of pure parietal strokes studied prospectively. 987 53

Tottering mice inherit a recessive mutation of the calcium channel alpha1A subunit that causes ataxia, polyspike discharges, and intermittent dystonic episodes. The calcium channel alpha1A subunit gene encodes the pore-forming protein of P/Q-type voltage-dependent calcium channels and is predominantly expressed in cerebellar granule and Purkinje neurons with moderate expression in hippocampus and inferior colliculus. Because calcium misregulation likely underlies the tottering mouse phenotype, calcium channel blockers were tested for their ability to block the motor episodes. Pharmacologic agents that specifically block L-type voltage-dependent calcium channels, but not P/Q-type calcium channels, prevented the inducible dystonia of tottering mutant mice. Specifically, the dihydropyridines nimodipine, nifedipine, and nitrendipine, the benzothiazepine diltiazem, and the phenylalkylamine verapamil all prevented restraint-induced tottering mouse motor episodes. Conversely, the L-type calcium channel agonist Bay K8644 induced stereotypic tottering mouse dystonic at concentrations significantly below those required to induce seizures in control mice. In situ hybridization demonstrated that L-type calcium channel alpha1C subunit mRNA expression was up-regulated in the Purkinje cells of tottering mice. Radioligand binding with [3H]nitrendipine also revealed a significant increase in the density of L-type calcium channels in tottering mouse cerebellum. These data suggest that although a P/Q-type calcium channel mutation is the primary defect in tottering mice, L-type calcium channels may contribute to the generation of the intermittent dystonia observed in these mice. The susceptibility of L-type calcium channels to voltage-dependent facilitation may promote this abnormal motor phenotype.
 ...
PMID:L-type calcium channels contribute to the tottering mouse dystonic episodes. 988 94


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>