A randomized, placebo-controlled trial of memantine for functional disability in amyotrophic lateral sclerosis

Intraspinal stem cell transplantation for amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disorder in which the loss of upper and lower motor neurons produces progressive weakness and eventually death. In the decades since the approval of riluzole, the only US Food and Drug Administration-approved medication to moderately slow progression of ALS, no new therapeutics have arisen to alter the course of the disease. This is partly due to our incomplete understanding of the complex pathogenesis of motor neuron degeneration. Stem cells have emerged as an attractive option in treating ALS, because they come armed with equally complex cellular machinery and may modulate the local microenvironment in many ways to rescue diseased motor neurons. Various stem cell types are being evaluated in preclinical and early clinical applications; here, we review the preclinical strategies and advances supporting the recent clinical translation of neural progenitor cell therapy for ALS. Specifically, we focus on the use of spinal cord neural progenitor cells and the pipeline starting from preclinical studies to the designs of phase I and IIa clinical trials involving direct intraspinal transplantation in humans.

Multifactorial Gene Therapy Enhancing the Glutamate Uptake System and Reducing Oxidative Stress Delays Symptom Onset and Prolongs Survival in the SOD1-G93A ALS Mouse Model

The 150-year-long search for treatments of amyotrophic lateral sclerosis (ALS) is still fueled by frustration over the shortcomings of available therapeutics. Contributing to the therapeutic limitations might be the targeting of a single aspect of this multifactorial-multisystemic disease. In an attempt to overcome this, we devised a novel multifactorial-cocktail treatment, using lentiviruses encoding: EAAT2, GDH2, and NRF2, that act synergistically to address the band and width of the effected excito-oxidative axis, reducing extracellular-glutamate and glutamate availability while improving the metabolic state and the anti-oxidant response. This strategy yielded particularly impressive results, as all three genes together but not separately prolonged survival in ALS mice by an average of 19-22 days. This was accompanied by improvement in every parameter evaluated, including body-weight loss, reflex score, neurologic score, and motor performance. We hope to provide a novel strategy to slow down disease progression and alleviate symptoms of patients suffering from ALS.

Flecainide in Amyotrophic Lateral Sclerosis as a Neuroprotective Strategy (FANS): A Randomized Placebo-Controlled Trial

Background

Abnormalities in membrane excitability and Na⁺ channel function are characteristic of amyotrophic lateral sclerosis (ALS). We aimed to examine the neuroprotective potential, safety and tolerability of the Na⁺ channel blocker and membrane stabiliser flecainide in ALS.

Methods

A double-blind, placebo-controlled, randomised clinical trial of flecainide (200 mg/day) for 32-weeks with a 12-week lead-in phase was conducted in participants with probable or definite ALS recruited from multiple Australian centres (ANZCT Registry number ACTRN12608000338369). Patients were reviewed by a cardiologist to rule out cardiac contraindications. Participants were randomly assigned (1:1) to flecainide or placebo using stratified permuted blocks by a central pharmacy. The primary outcome measure was the slope of decline of the ALS Functional Rating Scale-revised (ALS FRS-r) during the treatment period.

Findings

Between March 11, 2008 and July 1, 2010, 67 patients were screened, 54 of whom were randomly assigned to receive flecainide (26 patients) or placebo (28 patients). Four patients in the flecainide group and three patients in the placebo group withdrew from the study. One patient in the flecainide group died during the study, attributed to disease progression. Flecainide was generally well tolerated, with no serious adverse events reported in either group. There was no significant difference in the rate of decline in the primary outcome measure ALS-FRS-r between placebo and flecainide treated patients (Flecainide 0.65 [95% CI 0.49 to 0.98]; Placebo 0.81 [0.49 to 2.12] P = 0.50). However, the rate of decline of the neurophysiological index was significantly reduced in the flecainide group (Flecainide 0.06 [0.01 to 0.11]; Placebo 0.14 [0.09 to 0.19], P = 0.02). Placebo-treated patients demonstrated greater CMAP amplitude reduction during the course of the study in the subset of patients with a reduced baseline CMAP amplitude (Flecainide: − 15 ± 12%; Placebo − 59 ± 12%; P = 0.03). Flecainide-treated patients maintained stabilized peripheral axonal excitability over the study compared to placebo.

Interpretation

This pilot study indicated that flecainide was safe and potentially biologically effective in ALS. There was evidence that flecainide stabilized peripheral axonal membrane function in ALS. While the study was not powered to detect evidence of benefit of flecainide on ALS-FRS-r decline, further studies may demonstrate clinical efficacy of flecainide in ALS.

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To determine safety and neuroprotective potential, a double-blind, placebo-controlled, randomised trial of the Na⁺ channel blocking agent flecainide was conducted in ALS.

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Flecainide was well tolerated, with no serious adverse events.

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Although there was some evidence that flecainide stabilised peripheral axonal membrane function, the study was not powered to provide evidence of benefit on functional decline.

Changes in nerve excitability function occur in patients with amyotrophic lateral sclerosis (ALS). We conducted a double-blind, placebo-controlled, randomised clinical trial to examine the impact of a membrane/nerve stabilizer (flecainide) in ALS patients. Although there was some evidence that flecainide stabilised peripheral axonal membrane function in ALS, the study was not powered to find evidence that flecainide benefited patient function.

A comprehensive review of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a late-onset fatal neurodegenerative disease affecting motor neurons with an incidence of about 1/100,000. Most ALS cases are sporadic, but 5–10% of the cases are familial ALS. Both sporadic and familial ALS (FALS) are associated with degeneration of cortical and spinal motor neurons. The etiology of ALS remains unknown. However, mutations of superoxide dismutase 1 have been known as the most common cause of FALS. In this study, we provide a comprehensive review of ALS. We cover all aspects of the disease including epidemiology, comorbidities, environmental risk factor, molecular mechanism, genetic factors, symptoms, diagnostic, treatment, and even the available supplement and management of ALS. This will provide the reader with an advantage of receiving a broad range of information about the disease.

Item response theory analysis of the Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised in the Pooled Resource Open-Access ALS Clinical Trials Database

Our objective was to examine dimensionality and item-level performance of the Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised (ALSFRS-R) across time using classical and modern test theory approaches. Confirmatory factor analysis (CFA) and Item Response Theory (IRT) analyses were conducted using data from patients with amyotrophic lateral sclerosis (ALS) Pooled Resources Open-Access ALS Clinical Trials (PRO-ACT) database with complete ALSFRS-R data (n = 888) at three time-points (Time 0, Time 1 (6-months), Time 2 (1-year)). Results demonstrated that in this population of 888 patients, mean age was 54.6 years, 64.4% were male, and 93.7% were Caucasian. The CFA supported a 4* individual-domain structure (bulbar, gross motor, fine motor, and respiratory domains). IRT analysis within each domain revealed misfitting items and overlapping item response category thresholds at all time-points, particularly in the gross motor and respiratory domain items. Results indicate that many of the items of the ALSFRS-R may sub-optimally distinguish among varying levels of disability assessed by each domain, particularly in patients with less severe disability. Measure performance improved across time as patient disability severity increased. In conclusion, modifications to select ALSFRS-R items may improve the instrument's specificity to disability level and sensitivity to treatment effects.

Erythropoietin in amyotrophic lateral sclerosis: a multicentre, randomised, double blind, placebo controlled, phase III study

OBJECTIVE

To assess the efficacy of recombinant human erythropoietin (rhEPO) in amyotrophic lateral sclerosis (ALS).

METHODS

Patients with probable laboratory-supported, probable or definite ALS were enrolled by 25 Italian centres and randomly assigned (1:1) to receive intravenous rhEPO 40,000 IU or placebo fortnightly as add-on treatment to riluzole 100 mg daily for 12 months. The primary composite outcome was survival, tracheotomy or >23 h non-invasive ventilation (NIV). Secondary outcomes were ALSFRS-R, slow vital capacity (sVC) and quality of life (ALSAQ-40) decline. Tolerability was evaluated analysing adverse events (AEs) causing withdrawal. The randomisation sequence was computer-generated by blocks, stratified by centre, disease severity (ALSFRS-R cut-off score of 33) and onset (spinal or bulbar). The main outcome analysis was performed in all randomised patients and by intention-to-treat for the entire population and patients stratified by severity and onset. The study is registered, EudraCT 2009-016066-91.

RESULTS

We randomly assigned 208 patients, of whom 5 (1 rhEPO and 4 placebo) withdrew consent and 3 (placebo) became ineligible (retinal thrombosis, respiratory insufficiency, SOD1 mutation) before receiving treatment; 103 receiving rhEPO and 97 placebo were eligible for analysis. At 12 months, the annualised rate of death (rhEPO 0.11, 95% CI 0.06 to 0.20; placebo: 0.08, CI 0.04 to 0.17), tracheotomy or >23 h NIV (rhEPO 0.16, CI 0.10 to 0.27; placebo 0.18, CI 0.11 to 0.30) did not differ between groups, also after stratification by onset and ALSFRS-R at baseline. Withdrawal due to AE was 16.5% in rhEPO and 8.3% in placebo. No differences were found for secondary outcomes.

CONCLUSIONS

RhEPO 40,000 IU fortnightly did not change the course of ALS.

Preliminary evaluation of the sensitivity to change of DE-STA motor unit number estimation in the upper trapezius muscle in amyotrophic lateral sclerosis

OBJECTIVE

To compare the sensitivity to change of decomposition-enhanced spike-triggered averaging (DE-STA) motor unit number estimation (MUNE) in the upper trapezius (UT) to that of various clinical outcome measures in subjects with amyotrophic lateral sclerosis (ALS).

METHODS

Ten patients with clinically probable or definite ALS were assessed at baseline, 2, 4 and 6months with the following outcome measures: manual muscle testing in five upper extremity muscle groups, scapular elevation and elbow flexion peak force measured with hand-held dynamometry, MUNE, forced vital capacity and the Revised ALS Functional Rating Scale (ALSFRS-R).

RESULTS

ALSFRS-R was the only outcome measure for which there was a significant difference between baseline and 6months (p=0.034). ALSFRS-R had the largest standardized response mean (SRM), and was thus the most sensitive to change. MUNE demonstrated a decline over 6months and a moderate SRM (-0.63).

CONCLUSIONS

This study has demonstrated a moderate degree of sensitivity to change for DE-STA MUNE as applied to the UT in subjects with ALS.

SIGNIFICANCE

In this preliminary study, DE-STA MUNE detected motor unit loss over 6months, with a moderate degree of sensitivity, in the upper trapezius of subjects with ALS.

Gacyclidine improves the survival and reduces motor deficits in a mouse model of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder typified by a massive loss of motor neurons with few therapeutic options. The exact cause of neuronal degeneration is unknown but it is now admitted that ALS is a multifactorial disease with several mechanisms involved including glutamate excitotoxicity. More specifically, N-methyl-D-aspartate (NMDA)-mediated cell death and impairment of the glutamate-transport has been suggested to play a key role in ALS pathophysiology. Thus, evaluating NMDAR antagonists is of high therapeutic interest. Gacyclidine, also named GK11, is a high affinity non-competitive NMDAR antagonist that may protect against motor neuron death in an ALS context. Moreover, GK11 presents a low intrinsic neurotoxicity and has already been used in two clinical trials for CNS lesions. In the present study, we investigated the influence of chronic administration of two doses of GK11 (0.1 and 1 mg/kg) on the survival and the functional motor activity of hSOD1(G93A) mice, an animal model of ALS. Treatment started at early symptomatic age (60 days) and was applied bi-weekly until the end stage of the disease. We first confirmed that functional alteration of locomotor activity was evident in the hSOD1(G93A) transgenic female mice by 60 days of age. A low dose of GK11 improved the survival of the mice by 4.3% and partially preserved body weight. Improved life span was associated with a delay in locomotor function impairment. Conversely, the high dose treatment worsened motor functions. These findings suggest that chronic administration of GK11 beginning at early symptomatic stage may be beneficial for patients with ALS.

The neuroprotection exerted by memantine, minocycline and lithium, against neurotoxicity of CSF from patients with amyotrophic lateral sclerosis, is antagonized by riluzole

In a recent study we found that cerebrospinal fluids (CSFs) from amyotrophic lateral sclerosis (ALS) patients caused 20-30% loss of cell viability in primary cultures of rat embryo motor cortex neurons. We also found that the antioxidant resveratrol protected against such damaging effects and that, surprisingly, riluzole antagonized its protecting effects. Here we have extended this study to the interactions of riluzole with 3 other recognized neuroprotective agents, namely memantine, minocycline and lithium. We found: (1) by itself riluzole exerted neurotoxic effects at concentrations of 3-30 µM; this cell damage was similar to that elicited by 30 µM glutamate and a 10% dilution of ALS/CSF; (2) memantine (0.1-30 µM), minocycline (0.03-1 µM) and lithium (1-80 µg/ml) afforded 10-30% protection against ALS/CSF-elicited neurotoxicity, and (3) at 1-10 µM, riluzole antagonized the protection afforded by the 3 agents. These results strongly support the view that at the riluzole concentrations reached in the brain of patients, the neurotoxic effects of this drug could be masking the potential neuroprotective actions of new compounds being tested in clinical trials. Therefore, in the light of the present results, the inclusion of a group of patients free of riluzole treatment may be mandatory in future clinical trials performed in ALS patients with novel neuroprotective compounds.

Rodent models of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterised by the degeneration of upper and lower motor neurons. Recent advances in our understanding of some of the genetic causes of ALS, such as mutations in SOD1, TARDBP, FUS and VCP have led to the generation of rodent models of the disease, as a strategy to help our understanding of the pathophysiology of ALS and to assist in the development of therapeutic strategies. This review provides detailed descriptions of TDP-43, FUS and VCP models of ALS, and summarises potential therapeutics which have been recently trialled in rodent models of the disease. This article is part of a Special Issue entitled: Animal Models of Disease.

[Amyotrophic lateral sclerosis: update on etiological treatment]

Amyotrophic lateral sclerosis is a rare neurodegenerative disease. It is characterized by motoneurons progressive degeneration. Associated with a paralysis of the legs, arms and the respiratory muscles, its evolution is lethal. Riluzole is the only drug available with an marketing authorisation (autorisation de mise sur le marché [AMM]) in this indication. In the beginning stages of the disease it demonstrated a modest efficacy by prolonging survival for a few months. Although the physiopathological mechanisms of this disease have not been totally solved, the progression of knowledge in recent years in this area led to the development of a large number of neuroprotective agents which showed effective results in animal models of ALS and which could be good candidates for the treatment of ALS. Several clinical trials have been conducted about antiglutamatergic, antioxidant, antiapoptotic agents and growing cell factors but they failed to demonstrate efficacy on survival or quality of life. Therefore, clinical trials using innovative therapeutics and stem cells are ongoing and offer more distant hope.

Enhancing clinical trials in neurodegenerative disorders: lessons from amyotrophic lateral sclerosis

PURPOSE OF REVIEW

This review article is focused on strategies that may enhance clinical trial efficiency in neurodegenerative disorders, as demonstrated within the research field of amyotrophic lateral sclerosis (ALS).

RECENT FINDINGS

Unravelling ALS pathophysiology will result in an increased number of candidate therapeutics. Recent ALS clinical trials have employed novel study designs that expedite the drug development process and limit sample size, including futility, lead-in, selection, adaptive and sequential designs. The search for sensitive and specific biomarkers in ALS continues to develop, and they are essential in accelerating the drug discovery process. Several candidate cerebrospinal fluid (CSF), neuroimaging and electrophysiological biomarkers have been recently described in ALS, and some have been successfully employed as secondary outcome measures in clinical trials. The advent of web-based technologies has provided a complementary platform to expedite clinical trials, through electronic data capture, teleconferencing and online registries. In addition, the formation of ALS consortia has enhanced collaborative multicentre studies.

SUMMARY

ALS research studies have employed novel strategies to accelerate the efficiency and pace of drug discovery. The importance of adapting to novel measures that enhance study efficiency is not unique to ALS and can be applied to other neurodegenerative diseases in search of effective treatments.

CDP-choline is not protective in the SOD1-G93A mouse model of ALS

Important pathogenic factors in ALS include excitotoxicity and oxidative stress. Cytidine 5-diphosphocholine (CDP-choline) has recently been reported to have neuroprotective effects in animal models for neurodegenerative diseases, attributable to its anti-glutamatergic, anti-excitotoxic, anti-apoptotic and membrane-preserving properties. In this study we administered either CDP-choline or vehicle to transgenic SOD1-G93A mice daily via intraperitoneal (i.p.) injection starting before disease onset (day 30). By monitoring of survival, motor function, weight and general condition we examined possible therapeutic effects. Additional animals were used for histological studies to determine the effect of CDP-choline on motor neuron survival, astrocytosis and myelination in the spinal cord. Results showed that CDP-choline treatment modified neither the deterioration of general condition nor the loss of body weight. Survival of CDP-choline treated animals was not prolonged compared to vehicle treated controls. None of the behavioural motor function tests revealed differences between groups and no differences in motor neuron survival, astrocytosis or myelination were detected by histological analyses. In conclusion, our data from the transgenic mouse model do not strongly support further clinical validation of CDP-choline for the treatment of ALS.

Role of the N-methyl-d-aspartate receptors complex in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is an adult onset neurodegenerative disease pathologically characterized by the massive loss of motor neurons in the spinal cord, brain stem and cerebral cortex. There is a consensus in the field that ALS is a multifactorial pathology and a number of possible mechanisms have been suggested. Among the proposed hypothesis, glutamate toxicity has been one of the most investigated. Alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor mediated cell death and impairment of the glutamate-transport system have been suggested to play a central role in the glutamate-mediated motor neuron degeneration. In this context, the role played by the N-methyl-d-aspartate (NMDA) receptor has received considerable less attention notwithstanding its high Ca(2+) permeability, expression in motor neurons and its importance in excitotoxicity. This review overviews the critical role of NMDA-mediated toxicity in ALS, with a particular emphasis on the endogenous modulators of the NMDAR.

Progress in therapy development for amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that cannot be slowed substantially using any currently-available clinical tools. Through decades of studying sporadic and familial ALS (SALS and FALS), researchers are coming to understand ALS as a complex syndrome with diverse genetic and environmental etiologies. It is know appreciated that motor neuron degeneration in ALS requires active (gain of function) and passive (loss of function) events to occur in non-neuronal cells, especially astrocytes and microglia. These neuroinflammatory processes produce paracrine factors that detrimentally affect motor neurons, precipitating protein aggregation and compromising cytoskeletal integrity. The result is a loss of neuronal homeostasis and progressive die-back of motor axons culminating in death of the afflicted motor neurons. This review will discuss experimental therapeutics that have been tested in murine ALS models, with an emphasis on those that have progressed to human clinical trials. Reasons will be considered for the frequent failure of preclinical successes to translate into positive clinical outcomes. Finally, this review will explore current trends in experimental therapeutics for ALS with emphasis on the emerging interest in axon guidance signaling pathways as novel targets for pharmacological support of neural cytoskeletal structure and function in order to slow ALS.

Treatment for cramps in amyotrophic lateral sclerosis/motor neuron disease

BACKGROUND

Cramps are painful, involuntary muscle contractions. They commonly affect people with amyotrophic lateral sclerosis/motor neuron disease (ALS/MND) at all stages of the disease. To date, the treatment of muscle cramps in ALS has been largely empirical without any evidence from randomised controlled trials.

OBJECTIVES

To systematically assess the effect of interventions on muscle cramps as a primary or secondary endpoint or adverse event in people with ALS/MND.

SEARCH METHODS

We searched the Cochrane Neuromuscular Disease Group Specialized Register (14 February 2011), the Cochrane Central Register of Controlled Trials (Issue 1, 2011 in The Cochrane Library), MEDLINE (January 1966 to January 2011) and EMBASE (January 1980 to January 2011) and reference lists of articles searched using the terms motor neuron disease, motor neurone disease, motoneuron disease or amyotrophic lateral sclerosis. We contacted authors of trials for further information.

SELECTION CRITERIA

We included all randomised and quasi-randomised trials of oral medications in people with ALS which assessed cramps as a primary or secondary outcome measure or as an adverse event. We also included trials using subcutaneous or intravenous medications or physical therapy.

DATA COLLECTION AND ANALYSIS

All authors applied the selection criteria and assessed study quality independently, and all authors performed independent data extraction.

MAIN RESULTS

Twenty studies including 4789 participants were identified. Only one trial, of tetrahydrocannabinol (THC), assessed cramps as the primary endpoint. Thirteen studies assessed cramps as a secondary endpoint. The medications comprised vitamin E, baclofen, riluzole, L-threonine, xaliproden, indinavir, and memantine. Six studies assessed cramps as an adverse event. The medications comprised creatine, gabapentin, dextromethorphan, quinidine, and lithium. In all 20 studies no favourable effect for the treatment of cramps in ALS/MND could be demonstrated, but many studies were underpowered to draw a definite conclusion. A meta-analysis of two small studies showed a statistically nonsignificant result for the amino acid L-threonine for the treatment of cramps in ALS/MND. No study was identified using physical therapy as a therapeutic intervention for cramps.

AUTHORS' CONCLUSIONS

There is no evidence to support the use of any intervention for muscle cramps in ALS/MND. More and larger randomised controlled trials evaluating treatments for muscle cramps in ALS/MND are needed.

Current and prospective disease-modifying therapies for amyotrophic lateral sclerosis

INTRODUCTION

Amyotrophic lateral sclerosis (ALS) is a devastating illness of unclear etiology affecting motor neurons. It causes unremitting muscle paralysis, atrophy and death usually within 3 - 5 years from diagnosis. The human and economic costs for those affected are sobering. To date, tremendous efforts have failed to find a cure.

AREAS COVERED

An extensive literature search was undertaken using Medline and the Cochrane Systematic Review and Clinical Trial databases. Riluzole and investigational ALS drugs are discussed. Riluzole is the only approved disease-modifying therapy despite its modest effect on survival. Recent research has produced promising agents aimed at better disease control if not a cure. This review discusses agents targeting neuronal glutamate excitotoxicity, protein misfolding and accumulation, autophagy, apoptosis, mitochondrial dysfunction, free radical oxidative injury, immunomodulation, mutant mRNA counteraction, muscle physiology, neurotrophic factors and stem cell applications. The challenges in ALS drug development are highlighted.

EXPERT OPINION

Riluzole should be used for patients with definite, probable, suspected or possible ALS by World Federation of Neurology diagnostic criteria. Systematic monitoring for hepatic dysfunction, neutropenia and other serious adverse effects should be done routinely as outlined. All ALS patients should consider genetic screening and enrollment in ALS trials guided by the data reviewed.

A review of clinical trial designs in amyotrophic lateral sclerosis

SUMMARY Amyotrophic lateral sclerosis is a serious disease characterized by a rapid decline in the ability to carry out daily activities, which leads to death within 2–5 years of diagnosis. Numerous agents for slowing disease progression have been tested but only one (riluzole) has proven to be moderately successful. Here we review clinical trial designs with a focus on novel Phase II designs developed since 2005, that attempt to speed up the process of testing new agents. The review is organized by four features that are critical in defining a clinical trial: the comparison group, the end point, the method of analysis and the type of trial. We note continuing trends over the past 5 years toward more efficient designs with shorter duration trials, increased interest in biomarkers and use of well-characterized historical controls.

Emerging drugs for amyotrophic lateral sclerosis

INTRODUCTION

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neurodegenerative disease that results in increasing disability and that is uniformly fatal. Since its approval in the 1990s, riluzole remains the sole treatment for ALS offering modest survival benefit. While significant advances have been made in the symptomatic management of the disease, more effective drug therapy targeting disease progression is sorely needed.

AREAS COVERED

Advances in the understanding of pathogenic mechanisms involved in disease development and progression have provided multiple avenues for developing effective treatment strategies. This review highlights recent discoveries relating to these diverse mechanisms and their implications for the development of drug therapy. Previous human clinical trials that have targeted these pathways are mentioned and ongoing drug trials are discussed.

EXPERT OPINION

The search for effective drug therapy faces important challenges in the areas of basic science and animal research, translation of these results into human clinical trials, inherent bias in human studies and issues related to delays in clinical diagnosis. How these issues may be addressed and why ALS research constitutes fertile grounds for drug development not only for this devastating disease, but also for other more prevalent neurodegenerative diseases, is discussed in this review.

Emerging targets and treatments in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive motor neuron disease that is currently untreatable. Many compounds have been tested in laboratory-based models and in patients with ALS, but so far only one drug, riluzole, has shown efficacy, yet it only slightly slows disease progression. Several new insights into the causes of motor neuron death have led to the identification of some important novel targets for intervention. At no time have studies involved such a wide range of innovations and such advanced technologies. Many promising studies are underway to test potential targets that will hopefully translate into meaningful therapeutics for patients with ALS.

Inhibitory effect of memantine, an NMDA-receptor antagonist, on electroporation-induced inward currents in pituitary GH3 cells

The membrane electroporation-induced inward current (IMEP) in pituitary tumor (GH3) cells was characterized. This current emerges irregularly when membrane hyperpolarizations to -200 mV with a holding potential of -80 mV were elicited. Neither E-4031 (10 μM), glibenclamide (30 μM), nor ZD7288 (30 μM) caused any effects on IMEP. The single-channel conductance and pore radius were estimated to be around 1.12 nS and 1.7 nm, respectively. LaCl3- and memantidine (MEM)-induced block of this current was also examined. The IC50 value for LaCl3- and MEM-induced inhibition of IMEP was 35 and 75 μM, respectively. However, unlike LaCl3, MEM (300 μM) did not exert any effect on voltage-gated Ca2+ current. In inside-out configuration, MEM applied to either external or internal surface of the excised patch did not suppress the activity of ATP-sensitive K+ channels expressed in GH3 cells, although glibenclamide significantly suppressed channel activity. This study provides the first evidence to show that MEM, a non-competitive antagonist of N-methyl D-aspartate receptors, directly inhibits the amplitude of IMEP in pituitary GH3 cells. MEM-mediated block of IMEP in these cells is unlinked to its inhibition of glutamate-induced currents or ATP-sensitive K+ currents. The channel-suppressing properties of MEM might contribute to the underlying mechanisms by which it and its structurally related compounds affect neuronal or neuroendocrine function.