101
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Hegemann SCA, Palla A. New methods for diagnosis and treatment of vestibular diseases. F1000 MEDICINE REPORTS 2010; 2:60. [PMID: 21173877 PMCID: PMC2990630 DOI: 10.3410/m2-60] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Dizziness and vertigo are common complaints, with a lifetime prevalence of over 30%. This review provides a brief summary of the recent diagnostic and therapeutic advances in the field of neuro-otology. A special focus is placed on the clinical usefulness of vestibular tests. While these have markedly improved over the years, treatment options for vestibular disorders still remain limited. Available therapies for selected vestibular diseases are discussed.
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Affiliation(s)
- Stefan CA Hegemann
- Department of ENT- HNS, Zurich University Hospital8091 ZurichSwitzerland
| | - Antonella Palla
- Department of Neurology, Zurich University Hospital8091 ZurichSwitzerland
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102
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Abstract
Episodic ataxia type-2 (EA2) is an inherited movement disorder caused by mutations in the gene encoding the Ca(v)2.1alpha1 subunit of the P/Q-type voltage-gated calcium channel that result in an overall reduction in the P/Q-type calcium current. A consequence of these mutations is loss of precision of pacemaking in cerebellar Purkinje cells. This diminished precision reduces the information encoded by Purkinje cells and is thought to contribute to symptoms associated with this disorder. The loss of the precision of pacemaking in EA2 is the consequence of reduced activation of calcium-dependent potassium channels (K(Ca)) by the smaller calcium current and in vitro can be pharmacologically restored by K(Ca) activators. We used a well established mouse model of EA2, the tottering (tg/tg) mouse, to examine the potential therapeutic utility of one such Food and Drug Administration (FDA)-approved compound, chlorzoxazone (CHZ). Compared with wild-type Purkinje cells, we found the firing rate of tg/tg Purkinje cells in acutely prepared cerebellar slices to be very irregular. Bath application of CHZ successfully restored the precision of pacemaking in a dose-dependent manner. Oral administration of CHZ to tg/tg mice improved their baseline motor performance and reduced the severity, frequency, and duration of episodes of dyskinesia without producing any adverse effects. We propose the use of CHZ, which is currently FDA approved as a muscle relaxant, as a safe and novel treatment of EA2.
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103
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Abstract
Episodic ataxia type 2 (EA2) is a hereditary cerebellar ataxia associated with mutations in the P/Q-type voltage-gated calcium (Ca(2+)) channels. Therapeutic approaches for treatment of EA2 are very limited. Presently, the potassium (K(+)) channel blocker 4-aminopyridine (4-AP) constitutes the most promising treatment, although its mechanism of action is not understood. Here we show that, in contrast to what is commonly believed, therapeutic concentrations of 4-AP do not increase the inhibitory drive of cerebellar Purkinje cells. Instead, 4-AP restores the severely diminished precision of pacemaking in Purkinje cells of EA2 mutant mice by prolonging the action potential and increasing the action potential afterhyperpolarization. Consistent with this mode of action, the therapeutic efficacy of 4-AP was comparable, and not additive, to chlorzoxazone, an activator of Ca(2+)-dependent K(+) channels that also restores the precision of Purkinje cell pacemaking. The likely target of 4-AP at the concentrations used are the K(v)1 family of K(+) channels, possibly the K(v)1.5 subtype. Because at higher concentrations 4-AP blocks a large array of K(+) channels and is a proconvulsant, use of selective K(v)1 channel blockers is likely to be a safer substitute for treatment of cerebellar ataxia.
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104
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Hopkins AL, Clarke J. Episodic cerebellar dysfunction in a bichon frise: a canine case of episodic ataxia? J Small Anim Pract 2010; 51:444-6. [DOI: 10.1111/j.1748-5827.2010.00955.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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105
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Rajakulendran S, Graves TD, Labrum RW, Kotzadimitriou D, Eunson L, Davis MB, Davies R, Wood NW, Kullmann DM, Hanna MG, Schorge S. Genetic and functional characterisation of the P/Q calcium channel in episodic ataxia with epilepsy. J Physiol 2010; 588:1905-13. [PMID: 20156848 DOI: 10.1113/jphysiol.2009.186437] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Mutations in CACNA1A, which encodes the principal subunit of the P/Q calcium channel, underlie episodic ataxia type 2 (EA2). In addition, some patients with episodic ataxia complicated by epilepsy have been shown to harbour CACNA1A mutations, raising the possibility that P/Q channel dysfunction may be linked to human epilepsy. We undertook a review of all published CACNA1A EA2 cases and this showed that 7% have epilepsy--representing a sevenfold increased epilepsy risk compared to the background population risk (P<0.001). We also studied a series of 17 individuals with episodic ataxia accompanied by epilepsy and/or clearly epileptiform electroencephalograms (EEGs). We screened the entire coding region of CACNA1A for point mutations and rearrangements to determine if genetic variation in the gene is associated with the epilepsy phenotype, and measured the functional impact of all missense variations on heterologously expressed P/Q channels. We identified two large scale deletions and two new missense mutations in CACNA1A. When expressed, L621R had little detectable effect on P/Q channel function, while the other missense change, G540R, caused an approximately 30% reduction in current density. In nine patients we also identified the previously reported non-synonymous coding variants (E921D and E993V) which also resulted in impairment of P/Q channel function. Taken together, 12 of the 17 patients have genetic changes which decrease P/Q channel function. We conclude that variants in the coding region of CACNA1A that confer a loss of P/Q-type channel function are associated with episodic ataxia and epilepsy. Our data suggest that functional stratification of all variants, including common polymorphisms, rare variants and novel mutations, may provide new insights into the mechanisms of channelopathies.
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Affiliation(s)
- Sanjeev Rajakulendran
- MRC Centre for Neuromuscular Diseases, Department of Molecular Neuroscience, University College London, Institute of Neurology, London WC1N 3BG, UK
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106
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Wu ZZ, Li DP, Chen SR, Pan HL. Aminopyridines potentiate synaptic and neuromuscular transmission by targeting the voltage-activated calcium channel beta subunit. J Biol Chem 2009; 284:36453-36461. [PMID: 19850918 DOI: 10.1074/jbc.m109.075523] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Aminopyridines such as 4-aminopyridine (4-AP) are widely used as voltage-activated K(+) (Kv) channel blockers and can improve neuromuscular function in patients with spinal cord injury, myasthenia gravis, or multiple sclerosis. Here, we present novel evidence that 4-AP and several of its analogs directly stimulate high voltage-activated Ca(2+) channels (HVACCs) in acutely dissociated neurons. 4-AP, 4-(aminomethyl)pyridine, 4-(methylamino)pyridine, and 4-di(methylamino)pyridine profoundly increased HVACC, but not T-type, currents in dissociated neurons from the rat dorsal root ganglion, superior cervical ganglion, and hippocampus. The widely used Kv channel blockers, including tetraethylammonium, alpha-dendrotoxin, phrixotoxin-2, and BDS-I, did not mimic or alter the effect of 4-AP on HVACCs. In HEK293 cells expressing various combinations of N-type (Cav2.2) channel subunits, 4-AP potentiated Ca(2+) currents primarily through the intracellular beta(3) subunit. In contrast, 4-AP had no effect on Cav3.2 channels expressed in HEK293 cells. Furthermore, blocking Kv channels did not mimic or change the potentiating effects of 4-AP on neurotransmitter release from sensory and motor nerve terminals. Thus, our findings challenge the conventional view that 4-AP facilitates synaptic and neuromuscular transmission by blocking Kv channels. Aminopyridines can directly target presynaptic HVACCs to potentiate neurotransmitter release independent of Kv channels.
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Affiliation(s)
- Zi-Zhen Wu
- Division of Anesthesiology and Critical Care, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - De-Pei Li
- Division of Anesthesiology and Critical Care, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Shao-Rui Chen
- Division of Anesthesiology and Critical Care, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
| | - Hui-Lin Pan
- Division of Anesthesiology and Critical Care, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030; Program in Neuroscience, The University of Texas Graduate School of Biomedical Sciences, Houston, Texas 77225.
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107
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Abstract
BACKGROUND The lifelong prevalence of rotatory vertigo is 30%. Despite this high figure, patients with vertigo generally receive either inappropriate or inadequate treatment. However, the majority of vestibular disorders have a benign cause, take a favorable natural course, and respond positively to therapy. OBJECTIVE This review puts special emphasis on the medical rather than the physical, operative, or psychotherapeutic treatments available. METHODS A selected review of recent reports and studies on the medical treatment of peripheral and central vestibular disorders. RESULTS/CONCLUSIONS In vestibular neuritis, recovery of the peripheral vestibular function can be improved by oral corticosteroids; in Menière's disease, there is first evidence that high-dose, long-term administration of betahistine reduces attack frequency; carbamazepine or oxcarbamazepine is the treatment of first choice in vestibular paroxysmia, a disorder mainly caused by neurovascular cross-compression; the potassium channel blocker aminopyridine provides a new therapeutic principle for treatment of downbeat nystagmus, upbeat nystagmus, and episodic ataxia type 2.
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Affiliation(s)
- Thomas Brandt
- Ludwig-Maximilians-University, Institute of Clinical Neuroscience, Marchioninistr. 15, 81377 Munich, Germany.
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108
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Trujillo-Martín MM, Serrano-Aguilar P, Monton-Alvarez F, Carrillo-Fumero R. Effectiveness and safety of treatments for degenerative ataxias: a systematic review. Mov Disord 2009; 24:1111-24. [PMID: 19412936 DOI: 10.1002/mds.22564] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The aim of this study was to determine the effectiveness and safety of available treatment alternatives for degenerative ataxias (DA). We systematically reviewed studies that assess pharmacological, rehabilitative, or psychological treatments in patients with DA. Studies were included if they fulfilled prespecified criteria. All included clinical trials were scored for methodological quality. Main outcome measures were clinical status of neurological disorder, adverse events, and patient-based factors. Twenty-five studies were included. Most studies were of small sample sizes, wide age variations, and low scientific validity. Only one study gave information on physical rehabilitation and none on psychological therapy. The remaining 24 studies reported on the effects of different pharmacological treatments. Outcomes such as functional capacity and psychological functioning of patients were evaluated by few studies. Some evidence supports that 5-hydroxytryptophan is more effective than placebo improving neurological symptoms in patients with Friedreich ataxia (FA), olivopontocerebellar atrophy, or cerebellar atrophy. Idebenone is more effective than placebo for halting and reversing the hypertrophic cardiomyopathy associated with FA, but it seems unable to improve neurological semiology. Limited evidence for other therapies was found. No relevant side effects for drugs that shown some degree of effectiveness were reported. Availability of quality studies to evaluate the safety and efficacy of treatments for most DA is scarce. No valid information on the actual value of physical rehabilitation and psychological support as treatments for DA is available. Further investigations with improved trial designs are necessary.
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Affiliation(s)
- M Mar Trujillo-Martín
- Canary Islands Research and Health Foundation (Fundación Canaria de Investigación y Salud-FUNCIS), Santa Cruz de Tenerife, Canary Islands, Spain.
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109
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Tomlinson SE, Hanna MG, Kullmann DM, Tan SV, Burke D. Clinical neurophysiology of the episodic ataxias: insights into ion channel dysfunction in vivo. Clin Neurophysiol 2009; 120:1768-76. [PMID: 19734086 DOI: 10.1016/j.clinph.2009.07.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2008] [Revised: 07/03/2009] [Accepted: 07/03/2009] [Indexed: 01/02/2023]
Abstract
Clinical neurophysiology has become an invaluable tool in the diagnosis of muscle channelopathies, but the situation is less clear cut with neuronal channelopathies. The genetic episodic ataxias are a group of disorders with heterogeneous phenotype and genotype, but share in common the feature of intermittent cerebellar dysfunction. Episodic ataxia (EA) types 1 and 2 are the most widely recognised of the autosomal dominant episodic ataxias and are caused by dysfunction of neuronal voltage-gated ion channels. There are central and peripheral nervous system manifestations in both conditions, and they are therefore good models of neuronal channelopathies to study neurophysiologically. To date most work has focussed upon characterising the electrophysiological properties of mutant channels in vitro. This review summarises the role of voltage-gated potassium and calcium channels, mutations of which underlie the main types of episodic ataxia types 1 and 2. The clinical, genetic and electrophysiological features of EA1 and EA2 are outlined, and a protocol for the assessment of these patients is proposed.
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Affiliation(s)
- Susan E Tomlinson
- Institute of Clinical Neurosciences, Royal Prince Alfred Hospital and University of Sydney, Sydney, Australia.
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110
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Abstract
For several forms of acquired nystagmus, animal models exist, mathematical hypotheses have been proposed, and treatments are available. What insights could acquired nystagmus provide for congenital forms of nystagmus? Acquired periodic alternating nystagmus (PAN) is caused by instability of the velocity storage mechanism for vestibular eye movements; an adaptive mechanism produces the oscillations that have a period of about 4 minutes. Surprisingly, the ability of individuals with congenital forms of nystagmus to adapt their eye movements to new visual demands has received little study. Acquired pendular nystagmus (APN) may arise from instability in the neural integrator for eye movements; identification of the neurotransmitters contributing to normal gaze holding made it possible to identify candidate drugs for treatment of APN. Similar knowledge of the biology underlying of congenital forms of nystagmus might similarly suggest effective drugs. Downbeat nystagmus (DBN) is caused by cerebellar disease, which includes structural lesions affecting the flocculus and paraflocculus, and calcium channelopathies, such as episodic ataxia type 2 (EA2), for which a mouse model and effective treatment is available. Since some congenital forms of nystagmus are genetic in origin, then the possibility arises that they may be caused by a channelopathy, a hypothesis that suggests novel drugs for evaluation in randomized controlled trials.
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Affiliation(s)
- R John Leigh
- Department of Neurology, Veterans Affairs Medical Center and University Hospitals, Case Western Reserve University, Cleveland, Ohio 44106-5040, USA.
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111
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Blight AR, Henney HR. Pharmacokinetics of 14C-radioactivity after oral intake of a single dose of 14C-labeled fampridine (4-aminopyridine) in healthy volunteers. Clin Ther 2009; 31:328-35. [PMID: 19302905 DOI: 10.1016/j.clinthera.2009.02.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/26/2009] [Indexed: 11/30/2022]
Abstract
BACKGROUND Fampridine (4-aminopyridine) is a potassium channel blocker that has been evaluated as a treatment for patients with spinal cord injury and multiple sclerosis. OBJECTIVE The purpose of this study was to determine the pharmacokinetics of a single dose of an orally administered solution of (14)C-labeled fampridine in healthy volunteers. METHODS In this open-label, single-dose study conducted in an inpatient setting, healthy adult men were administered an oral solution containing 15 mg of (14)C-labeled fampridine (100 microCi) in a fasted state. In addition to blood sampling for analysis of plasma (14)C-radioactivity at prescribed intervals over 7 days, all urine and feces were collected for analysis of drug recovery and disposition. Urine samples were also analyzed for metabolic profiling. Plasma pharmacokinetic parameters of the (14)C-radiolabeled drug were determined using standard liquid-scintillation techniques. Recovery was calculated to provide the total amount of radioactivity excreted as a proportion of the original dose. Nonhydrolyzed and hydrolyzed urine extracts were analyzed for radioactivity and metabolites using reverse-phase, isocratic high-performance liquid chromatography with spectrophotometric and radioactive detection. Tolerability was assessed through evaluation of vital signs, hematologic and other laboratory parameters, and electrocardiography. RESULTS The 4 white male subjects had a mean (SD) age of 21 (2) years. No clinically significant abnormalities in vital signs, clinical chemistry, hematology, urinalysis, or electrocardiography were observed either before or during the study. Peak plasma radioactivity was reached at 1 hour after dosing, with a median concentration of 72.9 ng x mL(-1). There was complete disappearance of radioactivity by 24 hours (limit of quantitation, 400 disintegrations/min per peak), and the calculated median t(1/2) was 3.14 hours. Total cumulative recovery of (14)C-radioactivity was 96.36%, with only 0.51% of drug recovered in feces. On chromatography, 2 metabolites accounted for a low proportion of total urinary radioactivity (3% and 6% of total radioactivity in the interval from 0 to 4 hours after dosing; 17% and 9% in the interval from 8 to 12 hours after dosing). Three subjects reported mild and transient dizziness occurring 1 half-hour after dosing; this was considered possibly related to the study drug. CONCLUSION Fampridine administered as an oral solution was rapidly absorbed and was nearly completely and rapidly eliminated as unchanged drug via urinary excretion, suggesting that it is unlikely to undergo substantial metabolic transformation.
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112
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Janahmadi M, Goudarzi I, Kaffashian MR, Behzadi G, Fathollahi Y, Hajizadeh S. Co-treatment with riluzole, a neuroprotective drug, ameliorates the 3-acetylpyridine-induced neurotoxicity in cerebellar Purkinje neurones of rats: Behavioural and electrophysiological evidence. Neurotoxicology 2009; 30:393-402. [DOI: 10.1016/j.neuro.2009.02.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2008] [Revised: 01/03/2009] [Accepted: 02/18/2009] [Indexed: 01/22/2023]
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113
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Kalla R, Spiegel R, Wagner J, Rettinger N, Jahn K, Strupp M. [Pharmacotherapy of central oculomotor disorders]. DER NERVENARZT 2009; 79:1377-8, 1380-2, 1384-5. [PMID: 18633586 DOI: 10.1007/s00115-008-2516-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Nystagmus causes blurred vision due to oscillopsia, as well as impaired balance. Depending on etiology, additional cerebellar and brain stem signs may occur. We present the current pharmacotherapy of the most common forms of central nystagmus: downbeat nystagmus (DBN), upbeat nystagmus (UBN), acquired pendular nystagmus (APN), and congenital nystagmus (CGN). Recommended medical therapies are aminopyridines (4-AP) for DBN and UBN, gabapentin and memantine for CGN and APN, and baclofen for periodic alternating nystagmus (PAN).
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Affiliation(s)
- R Kalla
- Neurologische Klinik, Klinikum Grosshadern Ludwig-Maximilians-Universität (LMU) München, Marchioninistr. 15, 81377, München.
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114
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Jebas SR, Sinthiya A, Ravindran Durai Nayagam B, Schollmeyer D, Raj SAC. Bis(4-amino-pyridinium) tetra-chlorido-cobaltate(II). Acta Crystallogr Sect E Struct Rep Online 2009; 65:m521. [PMID: 21583764 PMCID: PMC2977578 DOI: 10.1107/s1600536809013270] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2009] [Accepted: 04/07/2009] [Indexed: 11/10/2022]
Abstract
In the title compound, (C5H7N2)2[CoCl4], the cobalt(II) ion is coordinated by four chloride ions in a slightly distorted tetrahedral geometry. The crystal packing is stabilized by intermolecular N—H⋯Cl hydrogen bonding, forming a three-dimensional network. The crystal was a non-merohedral twin emulating tetragonal symmetry, but being in fact orthorhombic.
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115
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Fun HK, John J, Jebas SR, Balasubramanian T. Bis(4-amino-pyridinium) bis(hydrogen oxalate) monohydrate. Acta Crystallogr Sect E Struct Rep Online 2009; 65:o748-9. [PMID: 21582480 PMCID: PMC2968938 DOI: 10.1107/s1600536809007247] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Accepted: 02/27/2009] [Indexed: 12/03/2022]
Abstract
In the title compound, 2C5H7N2+·2C2HO4−·H2O, the asymmetric unit consists of an aminopyridinium cation, an oxalic actetate anion and a half-molecule of water, which lies on a two-fold rotation axis. The crystal packing is consolidated by intermolecular O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds. The molecules are linked into an infinite one dimensional chain along [010].
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116
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Fun HK, John J, Jebas SR, Balasubramanian T. 4-Amino-pyridinium hydrogen succinate. Acta Crystallogr Sect E Struct Rep Online 2009; 65:o765-6. [PMID: 21582495 PMCID: PMC2968853 DOI: 10.1107/s1600536809006990] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2009] [Accepted: 02/25/2009] [Indexed: 11/23/2022]
Abstract
In the title salt, C5H7N2+·C4H5O4−, the asymmetric unit comprises an aminopyridinium cation and a hydrogen succinate anion as protonation of the aromatic N atom of the 4-aminopyridine molecule has occurred. The crystal packing is stabilized by intermolecular O—H⋯O and N—H⋯O hydrogen bonds that lead to a two-dimensional array. Short C—H⋯O contacts are also present.
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117
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Rodnitzky R. A 44-year-old man with dizziness since the teens. Mov Disord 2008. [DOI: 10.3109/9780203008454-19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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118
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Fun HK, Sinthiya A, Jebas SR, Ravindran Durai Nayagam B, Alfred Cecil Raj S. Octa-akis(4-amino-pyridine)-1κN,2κN-aqua-2κO-μ-carbonato-1:2κO,O':O''-dinickel(II) dichloride penta-hydrate. Acta Crystallogr Sect E Struct Rep Online 2008; 64:m1436-m1437. [PMID: 21580879 PMCID: PMC2959610 DOI: 10.1107/s1600536808033321] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2008] [Accepted: 10/14/2008] [Indexed: 05/30/2023]
Abstract
In the title compound, [Ni(2)(CO(3))(C(5)H(6)N(2))(8)(H(2)O)]Cl(2)·5H(2)O, one of the the Ni(II) ions is six-coordinated in a distorted octa-hedral geometry, with the equatorial plane defined by four pyridine N atoms from four amino-pyridine ligands, the axial positions being occupied by one water O and a carbonate O atom. The other Ni(II) ion is also six-coordinated, by four other pyridine N atoms from four other amino-pyridine ligands and two carbonate O atoms to complete a distorted octa-hedral geometry. In the crystal structure, mol-ecules are linked into an infinite three-dimensional network by O-H⋯O, N-H⋯Cl, N-H⋯O, O-H⋯N, C-H⋯O, C-H⋯N and C/N-H⋯π inter-actions involving the pyridine rings.
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Affiliation(s)
- Hoong-Kun Fun
- X-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia
| | - A Sinthiya
- Department of Electronics, St Josephs College, Tiruchirappalli 620 002, India
| | - Samuel Robinson Jebas
- X-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia
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119
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120
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Quah CK, Jebas SR, Fun HK. 4-Amino-pyridinium 4-nitro-benzoate 4-nitro-benzoic acid. Acta Crystallogr Sect E Struct Rep Online 2008; 64:o1878-9. [PMID: 21201092 PMCID: PMC2959422 DOI: 10.1107/s1600536808027761] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2008] [Accepted: 08/29/2008] [Indexed: 11/23/2022]
Abstract
The asymmetric unit of the title compound, C(5)H(7)N(2) (+)·C(7)H(4)NO(4) (-)·C(7)H(5)NO(4), consists of an amino-pyridinium cation, a 4-nitro-benzoate anion and a neutral 4-nitro-benzoic acid mol-ecule. The pyridine ring forms dihedral angles of 64.70 (5)° and 70.37 (5)°, respectively, with the benzene rings of 4-nitro-benzoic acid and 4-nitro-benzoate. In the crystal structure, the cations, anions and the neutral 4-nitro-benzoic acid mol-ecules are linked by O-H⋯O and N-H⋯O hydrogen bonds, forming a two-dimensional network parallel to (001). Adjacent networks are cross-linked via C-H⋯O hydrogen bonds and π-π stacking inter-actions [centroid-centroid distances 3.6339 (6) and 3.6566 (6) Å].
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Affiliation(s)
- Ching Kheng Quah
- X-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia
| | - Samuel Robinson Jebas
- X-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia
| | - Hoong-Kun Fun
- X-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia
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121
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Löhle M, Schrempf W, Wolz M, Reichmann H, Storch A. Potassium channel blocker 4‐aminopyridine is effective in interictal cerebellar symptoms in episodic ataxia type 2 — A video case report. Mov Disord 2008; 23:1314-6. [DOI: 10.1002/mds.22071] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Matthias Löhle
- Department of Neurology, Technical University of Dresden, Dresden, Germany
| | - Wiebke Schrempf
- Department of Neurology, Technical University of Dresden, Dresden, Germany
| | - Martin Wolz
- Department of Neurology, Technical University of Dresden, Dresden, Germany
| | - Heinz Reichmann
- Department of Neurology, Technical University of Dresden, Dresden, Germany
| | - Alexander Storch
- Department of Neurology, Technical University of Dresden, Dresden, Germany
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122
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Fun HK, Sinthya A, Jebas SR, Devadasan S. Tetra-kis(4-amino-pyridine-κN)dichlorido-copper(II) monohydrate. Acta Crystallogr Sect E Struct Rep Online 2008; 64:m853-4. [PMID: 21202731 PMCID: PMC2961768 DOI: 10.1107/s1600536808015778] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2008] [Accepted: 05/26/2008] [Indexed: 11/10/2022]
Abstract
The asymmetric unit of the title compound, [CuCl(2)(C(5)H(6)N(2))(4)]·H(2)O, contains two crystallographically independent complex mol-ecules and two water mol-ecules. The Cu(II) ion in each mol-ecule is six-coordinated in an elongated octa-hedral geometry, with the equatorial plane defined by four pyridine N atoms of four amino-pyridine ligands and the axial positions occupied by two Cl atoms. In the crystal structure, mol-ecules are linked into a three-dimensional framework by C-H⋯Cl, O-H⋯Cl, N-H⋯O, N-H⋯Cl and N-H⋯N hydrogen bonds and C/N-H⋯π inter-actions involving the pyridine rings.
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123
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Axonal function in a family with episodic ataxia type 2 due to a novel mutation. J Neurol 2008; 255:750-5. [DOI: 10.1007/s00415-008-0794-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2007] [Revised: 09/19/2007] [Accepted: 10/19/2007] [Indexed: 10/22/2022]
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124
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Fun HK, Jebas SR, Sinthiya A. 4-Amino-pyridinium 4-amino-benzene-sulfonate 4-ammonio-benzene-sulfonate monohydrate. Acta Crystallogr Sect E Struct Rep Online 2008; 64:o697-8. [PMID: 21202089 PMCID: PMC2960977 DOI: 10.1107/s1600536808006259] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2008] [Accepted: 03/06/2008] [Indexed: 11/29/2022]
Abstract
The asymmetric unit of the title compound, C5H7N2+·C6H6NO3S−·C6H7NO3S·H2O, contains one 4-ammoniobenzenesulfonate zwitterion (+H3NC6H4SO3−), one 4-aminobenzenesulfonate anion (H2NC6H4SO3−), one 4-aminopyridinium cation and two half-molecules of water, each lying on a twofold rotation axis. The various ions and molecules in the structure are linked through N—H⋯O, N—H⋯N and N—H⋯S hydrogen bonds and C—H—π interactions into a three-dimensional framework.
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125
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Strupp M, Brandt T. Diagnosis and treatment of vertigo and dizziness. DEUTSCHES ARZTEBLATT INTERNATIONAL 2008; 105:173-80. [PMID: 19629221 DOI: 10.3238/arztebl.2008.0173] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2007] [Accepted: 11/19/2007] [Indexed: 02/05/2023]
Abstract
INTRODUCTION Vertigo is not a separate disease process, but a multisensory and sensorimotor syndrome with various etiologies and pathogeneses. It is among the commonest symptoms presented to doctors, with a lifetime prevalence of around 20% to 30%. Patients have often consulted multiple physicians before a diagnosis is made and therapy initiated. METHODS Selective literature research and review of the guidelines of the German Neurological Society. RESULTS A careful history remains the cornerstone of diagnosis. Once the correct diagnosis is made, specific and effective treatments are available for most peripheral, central, and psychogenic forms of dizziness. Treatment may include medication, physiotherapy, and psychotherapy; a few limited cases may require surgical treatment. The treatment of choice for acute vestibular neuritis is the administration of corticosteroids. Menière's disease is treated with high-dose, long-term betahistine. A new approach to the management of downbeat and upbeat nystagmus, and of episodic ataxia type 2, involves the use of aminopyridines as potassium-channel blockers. Close multidisciplinary cooperation is essential in dizziness, and further multicenter studies are needed.
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Affiliation(s)
- Michael Strupp
- Neurologische Klinik der Universität München, Klinikum Grosshadern, Marchioninistrasse 15,Munich, Germany.
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126
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Glasscock E, Noebels JL. When a disease gene is not really a disease gene. FUTURE NEUROLOGY 2008. [DOI: 10.2217/14796708.3.2.103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Edward Glasscock
- Baylor College of Medicine, Department of Neurology, One Baylor Plaza, Houston, TX 77030, USA
| | - Jeffrey L Noebels
- Baylor College of Medicine, Department of Neurology, Department of Neuroscience & Department of Molecular & Human Genetics, One Baylor Plaza, Houston, TX 77030, USA
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128
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Strupp M, Kalla R, Glasauer S, Wagner J, Hüfner K, Jahn K, Brandt T. Aminopyridines for the treatment of cerebellar and ocular motor disorders. PROGRESS IN BRAIN RESEARCH 2008; 171:535-41. [DOI: 10.1016/s0079-6123(08)00676-6] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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129
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Modelling drug modulation of nystagmus. PROGRESS IN BRAIN RESEARCH 2008. [DOI: 10.1016/s0079-6123(08)00675-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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Kim JM, Ryu WS, Hwang YH, Kim JS. Aggravation of ataxia due to acetazolamide induced hyperammonaemia in episodic ataxia. J Neurol Neurosurg Psychiatry 2007; 78:771-2. [PMID: 17575025 PMCID: PMC2117686 DOI: 10.1136/jnnp.2006.105353] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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131
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Abstract
Fampridine-SR is a sustained-release tablet form of the K(+) channel-blocking compound 4-aminopyridine that has been shown to restore conduction in focally demyelinated axons, to enhance synaptic transmission in many types of neurons and to potentiate muscle contraction. The present review describes the mechanism of action and chemistry of Fampridine-SR, its pharmacokinetics and safety, and the outcomes of clinical trials of its safety and efficacy for enhancing neuromuscular function in patients with multiple sclerosis or spinal cord injury. Randomized clinical trials completed to date indicate that this form of K(+) channel blockade may be useful for the improvement of walking ability in patients with multiple sclerosis.
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Affiliation(s)
- Keith C Hayes
- The University of Western Ontario, Department of Physical Medicine & Rehabilitation, London, Ontario, Canada.
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132
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Tilikete C, Pisella L, Pélisson D, Vighetto A. Oscillopsies : approches physiopathologique et thérapeutique. Rev Neurol (Paris) 2007; 163:421-39. [PMID: 17452944 DOI: 10.1016/s0035-3787(07)90418-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Oscillopsia is an illusion of an unstable visual world. It is associated with poor visual acuity and is a disabling and stressful symptom reported by numerous patients with neurological disorders. The goal of this paper is to review the physiology of the systems subserving stable vision, the various pathophysiological mechanisms of oscillopsia and the different treatments available. Visual stability is conditioned by two factors. First, images of the seen world projected onto the retina have to be stable, a sine qua non condition for foveal discriminative function. Vestibulo-ocular and optokinetic reflexes act to stabilize the retinal images during head displacements; ocular fixation tends to limit the occurrence of micro ocular movements during gazing; a specific system also acts to maintain the eyes stable during eccentric gaze. Second, although we voluntary move our gaze (body, head and eye displacements), the visual world is normally perceived as stable, a phenomenon known as space constancy. Indeed, complex cognitive processes compensate for the two sensory consequences of gaze displacement, namely an oppositely-directed retinal drift and a change in the relationship between retinal and spatial (or subject-centered) coordinates of the visual scene. In patients, oscillopsia most often results from abnormal eye movements which cause excessive motion of images on the retina, such as nystagmus or saccadic intrusions or from an impaired vestibulo-ocular reflex. Understanding the exact mechanisms of impaired eye stability may lead to the different treatment options that have been documented in recent years. Oscillopsia could also result from an impairment of spatial constancy mechanisms that in normal condition compensate for gaze displacements, but clinical data in this case are scarce. However, we suggest that some visuo-perceptive deficits consecutive to temporo-parietal lesions resemble oscillopsia and could result from a deficit in elaborating spatial constancy.
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Affiliation(s)
- C Tilikete
- Unité de Neuro-Ophtalmologie, Hôpital Neurologique, Hospices Civils de Lyon, Bron.
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133
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Abstract
Episodic ataxia type 2 (EA 2) is a rare neurological disorder of autosomal dominant inheritance resulting from dysfunction of a voltage-gated calcium channel. It manifests with recurrent disabling attacks of imbalance, vertigo, and ataxia, and can be provoked by physical exertion or emotional stress. In the spell-free interval, patients present with central ocular motor dysfunction, mainly downbeat nystagmus. A slow progression of cerebellar signs accompanied by a slight atrophy of midline cerebellar structures is commonly observed during the course of the disease. EA 2 is caused most often by the loss of function mutations of the calcium channel gene CACNA1A, which encodes the Ca(v)2.1 subunit of the P/Q-type calcium channel and is primarily expressed in Purkinje cells. To date, more than 30 mutations have been described. Two effective treatment options have been established for EA 2: acetazolamide (ACTZ), which probably changes the intracellular pH and thereby the transmembraneous potential, and 4-aminopyridine (4-AP), a potassium channel blocker. Approximately 70% of all patients respond to treatment with ACTZ, but the effect is often only transient. In an open trial, 4-AP prevented attacks in five of six patients with EA 2, most likely by increasing the resting activity and excitability of the Purkinje cells. These findings were confirmed by experiments in animal models of EA 2. Many aspects of the pathophysiology (e.g., induction of the attacks) and treatment of EA 2 (e.g., mode of action of ACTZ and 4-AP) still remain unclear and need to be addressed in further animal and clinical studies.
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Affiliation(s)
- Michael Strupp
- Department of Neurology, University of Munich, Munich, Germany.
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Venance SL, Herr BE, Griggs RC. Challenges in the design and conduct of therapeutic trials in channel disorders. Neurotherapeutics 2007; 4:199-204. [PMID: 17395129 DOI: 10.1016/j.nurt.2007.01.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Neurologic channelopathies are rare, inherited paroxysmal disorders of muscle (e.g., the periodic paralyses and nondystrophic myotonias) and brain (e.g., episodic ataxias, idiopathic epilepsies, and familial hemiplegic migraine). Mutation is necessary but not sufficient for phenotypic expression and there are no simple phenotype-genotype relationships. Attacks may be spontaneous or triggered, with affected individuals often asymptomatic and neurologically normal between attacks. Performance of daily activities may be affected by the unpredictable nature; often late-onset degenerative changes cause permanent disability; for example, muscle atrophy and fixed weakness in periodic paralysis and cerebellar atrophy and progressive ataxia in the episodic ataxias. Currently, the natural history of these disorders is being defined. Clearly, the established methodologies for randomized controlled clinical trials are not feasible for rare diseases and innovative trial design is essential. There is a requirement for clinically relevant outcome measures for episodic disorders. Increasing our knowledge of the pathophysiology will help in targeting and designing rational therapeutic approaches. We will use the current understanding of the neurological channelopathies to illustrate some of the opportunities, challenges, and strategies in bringing safe and effective treatments to patients. There are reasons for optimism that new partnerships between clinical investigators, government, patient advocacy groups, and industry will prevent symptoms and progression of the neurological channelopathies.
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135
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Haan J, Kors EE, Vanmolkot KRJ, van den Maagdenberg AMJM, Frants RR, Ferrari MD. Migraine genetics: an update. Curr Pain Headache Rep 2006; 9:213-20. [PMID: 15907261 DOI: 10.1007/s11916-005-0065-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
A growing interest in genetic research in migraine has resulted in the identification of several chromosomal regions that are involved in migraine. However, the identification of mutations in the genes for familial hemiplegic migraine (FHM) forms the only true molecular genetic knowledge of migraine thus far. The increased number of mutations in the FHM1 (CACNA1A) and the FHM2 (ATP1A2) genes allow studying the relationship between genetic findings in both genes and the clinical features in patients. A wide spectrum of symptoms is seen in patients. Additional cerebellar ataxia and (childhood) epilepsy can occur in FHM1 and FHM2. Functional studies show a dysfunction in ion transport as the key factor in the pathophysiology of (familial hemiplegic) migraine that predict an increased susceptibility to cortical spreading depression--the underlying mechanism of migraine aura.
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Affiliation(s)
- J Haan
- Department of Neurology, Leiden University Medical Centre, P.O. Box 9600, 2300 RC Leiden, The Netherlands. E-mail:
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136
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Martina M, Metz AE, Bean BP. Voltage-dependent potassium currents during fast spikes of rat cerebellar Purkinje neurons: inhibition by BDS-I toxin. J Neurophysiol 2006; 97:563-71. [PMID: 17065256 DOI: 10.1152/jn.00269.2006] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We characterized the kinetics and pharmacological properties of voltage-activated potassium currents in rat cerebellar Purkinje neurons using recordings from nucleated patches, which allowed high resolution of activation and deactivation kinetics. Activation was exceptionally rapid, with 10-90% activation in about 400 mus at +30 mV, near the peak of the spike. Deactivation was also extremely rapid, with a decay time constant of about 300 mus near -80 mV. These rapid activation and deactivation kinetics are consistent with mediation by Kv3-family channels but are even faster than reported for Kv3-family channels in other neurons. The peptide toxin BDS-I had very little blocking effect on potassium currents elicited by 100-ms depolarizing steps, but the potassium current evoked by action potential waveforms was inhibited nearly completely. The mechanism of inhibition by BDS-I involves slowing of activation rather than total channel block, consistent with the effects described in cloned Kv3-family channels and this explains the dramatically different effects on currents evoked by short spikes versus voltage steps. As predicted from this mechanism, the effects of toxin on spike width were relatively modest (broadening by roughly 25%). These results show that BDS-I-sensitive channels with ultrafast activation and deactivation kinetics carry virtually all of the voltage-dependent potassium current underlying repolarization during normal Purkinje cell spikes.
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Affiliation(s)
- Marco Martina
- Department of Physiology, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611, USA.
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137
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Wang D, Darwish DS, Schreurs BG. Effects of 4-aminopyridine on classical conditioning of the rabbit (Oryctolagus cuniculus) nictitating membrane response. Behav Pharmacol 2006; 17:319-29. [PMID: 16914950 DOI: 10.1097/01.fbp.0000224381.56121.15] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
A large body of data suggests that potassium channels may play an important role in learning and memory. Previous in-vitro research in a number of species including Hermissenda and the rabbit suggests that a 4-aminopyridine-sensitive transient potassium channel may be involved in classical conditioning. We investigated the effects of in-vivo 4-aminopyridine administration (0.5 mg/kg) on classical conditioning of the rabbit nictitating membrane response using a battery of tests designed to assess the associative, sensory, and motor contributors of 4-aminopyridine to responding. 4-Aminopyridine enhanced both classical conditioning and conditioning-specific reflex modification compared with a saline vehicle control, and these effects had several nonassociative components including an increase in the frequency of responding to both the conditioned and the unconditioned stimuli, suggesting a sensitizing effect of the drug. Although 4-aminopyridine can have peripheral effects, it may also modify cerebellar excitability or hippocampal neurotransmitter balance resulting in heightened responsiveness to stimulation.
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Affiliation(s)
- Desheng Wang
- Department of Physiology and Pharmacology, Blanchette Rockefeller Neurosciences Institute, West Virginia University School of Medicine, Morgantown, West Virginia 26506, USA
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138
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McKeown L, Robinson P, Jones OT. Molecular basis of inherited calcium channelopathies: role of mutations in pore-forming subunits. Acta Pharmacol Sin 2006; 27:799-812. [PMID: 16787562 DOI: 10.1111/j.1745-7254.2006.00394.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The pore-forming alpha subunits of voltage-gated calcium channels contain the essential biophysical machinery that underlies calcium influx in response to cell depolarization. In combination with requisite auxiliary subunits, these pore subunits form calcium channel complexes that are pivotal to the physiology and pharmacology of diverse cells ranging from sperm to neurons. Not surprisingly, mutations in the pore subunits generate diverse pathologies, termed channelopathies, that range from failures in excitation-contraction coupling to night blindness. Over the last decade, major insights into the mechanisms of pathogenesis have been derived from animals showing spontaneous or induced mutations. In parallel, there has been considerable growth in our understanding of the workings of voltage-gated ion channels from a structure-function, regulation and cell biology perspective. Here we document our current understanding of the mutations underlying channelopathies involving the voltage-gated calcium channel alpha subunits in humans and other species.
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Affiliation(s)
- Lynn McKeown
- Faculty of Life Sciences, the University of Manchester, Manchester, UK
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139
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de Theije-Kors E, Haan J. Hemiplegic and Basilar-type Migraine: Epidemiology, Genetics, and Mechanisms. ACTA ACUST UNITED AC 2006. [DOI: 10.1111/j.1743-5013.2006.00036.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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140
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Scoggan KA, Friedman JH, Bulman DE. CACNA1A mutation in a EA-2 patient responsive to acetazolamide and valproic acid. Can J Neurol Sci 2006; 33:68-72. [PMID: 16583725 DOI: 10.1017/s0317167100004728] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND Episodic ataxia type-2 (EA-2) is an autosomal dominant neurological disorder that has been shown to result from mutations in the CACNA1A gene encoding the P/Q-type calcium channel. Affected individuals experience episodes of cerebellar ataxia usually associated with migraine symptoms, interictal nystagmus, mild residual and in some cases a progressive cerebellar incoordination and respond to acetazolamide treatment. We identified a patient with a positive family history for episodic ataxia, who was originally diagnosed with epilepsy and treated with valproic acid. Subsequent examination revealed that the symptoms were consistent with a diagnosis of EA-2. The patient responded positively to a combination of acetazolamide and valproic acid. Molecular genetic analysis of the CACNA1A gene was performed in order to confirm a diagnosis of EA-2. METHODS The CACNA1A gene was evaluated for mutations using single strand conformational polymorphism analysis and direct DNA sequencing. Allele specific oligo hybridization was used to confirm that the mutation was segregating with only affected family members and was not present in the control group. RESULTS In this study we identified a new missense mutation in exon 12 of the CACNA1A gene from a patient with EA-2 whose symptoms could be controlled with a combination of acetazolamide and valproic acid. This G to A transition changes a highly conserved glutamic acid residue to a lysine residue in domain II S2 of the P/Q-type calcium channel alpha1A subunit. CONCLUSIONS The use of valproic acid in treating patients with EA-2 is not well documented. Here we describe a patient with a novel mutation in the CACNA1A gene who responded positively to a combination of acetazolamide and valproic acid.
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141
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Strupp M, Brandt T. Pharmacological advances in the treatment of neuro-otological and eye movement disorders. Curr Opin Neurol 2006; 19:33-40. [PMID: 16415675 DOI: 10.1097/01.wco.0000196156.00481.e1] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW First, to describe the current pharmacological treatment options for peripheral and central vestibular, cerebellar, and ocular motor disorders. Second, to identify vestibular and ocular motor disorders in which treatment trials are warranted. RECENT FINDINGS Peripheral vestibular disorders: In vestibular neuritis recovery of the peripheral vestibular function can be improved by treatment with oral corticosteroids. In Ménière's disease treatment strategies range from low-salt diet, diuretics, and betahistine, to intratympanic injection of corticosteroids or gentamicin. Unfortunately most of the trials on Ménière's disease do not have an up-to-date design. In bilateral vestibulopathy steroids do not seem to improve vestibular function.Central vestibular, cerebellar, and ocular motor disorders: The use of aminopyridines introduced a new therapeutic principle in the treatment of downbeat and upbeat nystagmus and episodic ataxia type 2 (EA2). These potassium channel blockers presumably increase the activity and excitability of cerebellar Purkinje cells, thereby augmenting the inhibitory influence of these cells on vestibular and cerebellar nuclei. A few studies showed that baclofen improves periodic alternating nystagmus, and gabapentin and memantine, pendular nystagmus. Many other eye movement disorders, however, such as ocular flutter, opsoclonus, central positioning, or see-saw nystagmus are still difficult to treat. SUMMARY Although progress has been made in the treatment of vestibular neuritis, downbeat and upbeat nystagmus, as well as EA2, state-of-the-art trials must still be performed on many vestibular and ocular motor disorders, namely Ménière's disease, bilateral vestibulopathy, vestibular paroxysmia, vestibular migraine, and many forms of central eye movement disorders.
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143
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Weisz CJC, Raike RS, Soria-Jasso LE, Hess EJ. Potassium channel blockers inhibit the triggers of attacks in the calcium channel mouse mutant tottering. J Neurosci 2006; 25:4141-5. [PMID: 15843617 PMCID: PMC6724952 DOI: 10.1523/jneurosci.0098-05.2005] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Humans with the disorder episodic ataxia type 2 (EA2) and the tottering mouse mutant exhibit episodic attacks induced by emotional and chemical stress. Both the human and mouse disorders result from mutations in CACNA1A, the gene encoding the alpha(1)2.1 subunit of Ca(v)2.1 voltage-gated calcium channels. These mutations predict reduced calcium currents, particularly in cerebellar Purkinje cells, where these channels are most abundant. 4-Aminopyridine (4-AP), a nonselective blocker of K(v) voltage-gated potassium channels, alleviates attacks of ataxia in EA2 patients. To test the specificity of the effect for K(v) channels, aminopyridine analogs were assessed for their ability to ameliorate attacks of dyskinesia in tottering mice. 4-AP and 3,4-diaminopyridine (3,4-DiAP), which have relatively high affinities for K(v) channels, reduced the frequency of restraint- and caffeine-induced attacks. Furthermore, microinjection of 3,4-DiAP into the cerebellum completely blocked attacks in tottering mice. Other aminopyridine analogs reduced attack frequency but, consistent with their lower affinities for K(v) channels, required comparatively higher doses. These results suggest that aminopyridines block tottering mouse attacks via cerebellar K(v) channels. That both stress- and caffeine-induced attacks were blocked by aminopyridines suggests that these triggers act via similar mechanisms. Although 4-AP and 3,4-DiAP were effective in preventing attacks in tottering mice, these compounds did not affect the severity of "breakthrough" attacks that occurred in the presence of a drug. These results suggest that the aminopyridines increase the threshold for attack initiation without mitigating the character of the attack, indicating that attack initiation is mediated by mechanisms that are independent of the neurological phenotype.
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Affiliation(s)
- Catherine J C Weisz
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA
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Strupp M, Kalla R, Freilinger T, Dichgans M, Brandt T. Dysfunction of the brain calcium channel CaV2.1 in absence epilepsy and episodic ataxia--a comment. ACTA ACUST UNITED AC 2005; 128:E32; author reply E33. [PMID: 15900025 DOI: 10.1093/brain/awh440] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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145
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Hanna MG, Graves TD, Jaffe S, Imbrici P, Kullmann DM. Dysfunction of the brain calcium channel CaV2.1 in absence epilepsy and episodic ataxia—authors' response. Brain 2005. [DOI: 10.1093/brain/awh439] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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146
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Abstract
PURPOSE OF REVIEW This review focuses on three neuro-otological syndromes, which are all marked by rapid scientific progress on the one hand but under-recognition or undertreatment on the other: benign paroxysmal positional vertigo and its variants, superior semicircular canal dehiscence syndrome, and migrainous vertigo. RECENT FINDINGS The efficacy of Epley's maneuver for treatment of benign paroxysmal positional vertigo has been convincingly demonstrated by a meta-analysis of nine randomized controlled trials. Head vibration during Epley's procedure and keeping upright for 48 h after effective treatment do not improve the outcome. Superior canal dehiscence syndrome presents not only with sound and pressure-induced vertigo but also with conductive hearing loss at low frequencies. Migrainous vertigo may present not only with spontaneous attacks but also with positional vertigo or with chronic dizziness and imbalance. Vestibular rehabilitation has been proven to relieve chronic dizziness and visual vertigo. SUMMARY Recent studies have eliminated several white spots on the neuro-otological map. However, many areas are still unexplored, particularly with regard to treatment of specific vestibular syndromes where randomized controlled trials are just at their beginning.
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Affiliation(s)
- Thomas Lempert
- Department of Neurology, Schlosspark-Klinik, Charité, Humboldt University, Berlin, Germany.
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147
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Abstract
Acquired and congenital nystagmus often causes decreased visual acuity as a direct result of the inability to maintain stable foveal vision. In addition, acquired nystagmus causes a disabling subjective sensation of movement of the visual world called oscillopsia. The eye movements themselves do not require treatment if the patient is asymptomatic. However, therapy is necessary if visual disability is present. Treatments based in pharmacologic mechanisms are preferred. There are few controlled treatment trials and therapeutic efficacy generally is sought in a trial and error approach, depending on the type of nystagmus present. Treatment with 3,4-diaminopyridine and 4-aminopyridine recently have been shown to be effective for downbeat nystagmus. Gabapentin, baclofen, and clonazepam also are useful in some patients with downbeat nystagmus. Baclofen is the therapy of choice for periodic alternating nystagmus. Gabapentin often is effective for acquired pendular nystagmus. Clonazepam and valproate also may be effective for acquired pendular nystagmus. Memantine now is available in the United States and is promising in the treatment of pendular nystagmus. Optical devices that negate the negative effects of nystagmus continue to undergo development research. These and other medical, surgical, and optical devices are potentially useful alone or in combination with other therapies.
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Affiliation(s)
- Janet C Rucker
- Department of Neurology, Case Western Reserve School of Medicine, Hanna House 5th Floor, 11100 Euclid Avenue, Cleveland, OH 44106, USA.
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