Paraoxonase 1 (PON1) organophosphate hydrolysis is not reduced in ALS.

OBJECTIVE: Four recent studies report a genetic association of the paraoxonase locus with sporadic amyotrophic lateral sclerosis (ALS). We tested the hypothesis that this association correlates with functional changes in paraoxonase 1 (PON1, MIM 168820). METHODS: Sera from 140 ALS participants; 153 age-, race-, and sex-matched controls; and 30 matched CSF samples were tested for paraoxonase, diazoxonase, and arylesterase activities. Participants with ALS were genotyped using tagging single nucleotide polymorphisms across the PON locus. Survival data and enzyme activity were correlated with genotype. RESULTS: There was a trend toward increased paraoxonase activity in ALS compared with controls (mean control paraoxonase 701.9 +/- 469.7 U/L, mean ALS 792.5 +/- 574.1 U/L; p = 0.066 after correction) which correlated with increased frequency of the homozygous arginine (RR) variant of PON1(Q192R) (p = 0.004). There was no significant difference in PON1 protein levels, or arylesterase or diazoxonase activities. Organophosphate hydrolysis rates had no effect on ALS survival. CONCLUSIONS: Contrary to expectations, PON1 protein, paraoxonase, diazoxonase, and arylesterase activities were not reduced in amyotrophic lateral sclerosis (ALS). The increase in PON1(R192) frequency in ALS in our study supports previous genetic susceptibility studies. Our findings suggest that the influence of PON1 polymorphisms on ALS susceptibility is not due to reduced organophosphate hydrolysis.

Quantification of reverse transcriptase in ALS and elimination of a novel retroviral candidate.

BACKGROUND: Retroviral involvement in amyotrophic lateral sclerosis (ALS) has been suspected for several years since the recognition that both murine and human retroviruses can cause ALS-like syndromes. Nonquantitative studies have demonstrated the retroviral enzyme reverse transcriptase (RT) in ALS patients' sera, but the amount and source of RT activity are unknown. We therefore developed a quantitative assay to study RT levels in ALS and examined the possibility that the recently discovered human gammaretrovirus XMRV (xenotropic MuLV-related virus) might be the source of the RT activity. METHODS: A quantitative product-enhanced RT assay was used to measure RT activity levels in serum and CSF. XMRV sequences were sought by PCR analysis of DNA and RNA extracted from blood. RESULTS: Fifty percent of ALS patients' sera contained >6 x 10(-8) RT units/mL as opposed to 7% of control sera (p = 0.008). The levels of RT activity in ALS patients were comparable to the levels observed in patients infected with HIV. RT activity was detected in only 1 of 25 CSF samples tested. XMRV sequences were not found in any of 25 nucleic acid extracts obtained from ALS patients' blood. CONCLUSIONS: These findings further support the concept of retroviral involvement in amyotrophic lateral sclerosis (ALS) and demonstrate that serum is more suitable than CSF for assay of reverse transcriptase (RT) activity in this disease. The levels of serum RT activity detected are comparable to those found in HIV infection. XMRV is not detectable in the blood of ALS patients, and the agent responsible for ALS-associated RT activity therefore remains unidentified.

Revised statistical motor unit number estimation in the Celecoxib/ALS trial.

Techniques to estimate motor unit number (MUNE) measure the number of functioning motor units in a muscle. As amyotrophic lateral sclerosis (ALS) is characterized by progressive motor unit loss, this disease offers an ideal setting for the use of MUNE. Statistical MUNE was employed in a recent multicenter trial of creatine in ALS, and was shown to be reliable, reproducible, and to decline with disease progression. However, motor unit amplitude stayed constant over 7 months, a finding believed to reflect an artifact of the method. The statistical method was revised to reflect more accurately the presence of larger motor units and employed in a 12-month study of Celecoxib in ALS. MUNE declined by 49% in 12 months; however, motor unit amplitude again stayed constant over the same period. Statistical MUNE estimates motor unit number based on the variability of response to a repeated stimulus of constant strength, with an underlying assumption that this variability is due solely to the number of motor units responding in an intermittent manner. Based on studies showing that single motor units in ALS display excessive amplitude variability when stimulated repeatedly, we show that response variability in ALS patients is in large part due to single unit changes. Thus, we conclude that the statistical method is not an appropriate measure of motor unit number in any disease associated with motor unit instability.

Facial onset sensory and motor neuronopathy (FOSMN syndrome): a novel syndrome in neurology.

A 'syringomyelia-like' syndrome has been infrequently reported in neurological disorders such as Tangiers disease and lepromatous leprosy. This study reports a novel 'syringomyelia-like' syndrome in four adult male patients, which we have termed facial onset sensory and motor neuronopathy, or FOSMN syndrome, that appears to have a neurodegenerative aetiology. Clinical, neurophysiological and pathological data of four patients were reviewed, including the autopsy in one patient. Four male patients (mean age at onset 43), initially developed paraesthesiae and numbness in a trigeminal nerve distribution, which slowly progressed to involve the scalp, neck, upper trunk and upper limbs in sequential order. Motor manifestations, including cramps, fasciculations, dysphagia, dysarthria, muscle weakness and atrophy developed later in the course of the illness. Neurophysiological findings revealed a generalized sensory motor neuronopathy of caudally decreasing severity in all four patients. Autopsy in one patient disclosed loss of motoneurons in the hypoglossal nucleus and cervical anterior horns, along with loss of sensory neurons in the main trigeminal sensory nucleus and dorsal root ganglia. FOSMN syndrome appears to be a slowly progressive neurodegenerative disorder, whose pathogenesis remains to be determined.

Neuroprotective agents for clinical trials in ALS: a systematic assessment.

BACKGROUND: Riluzole is currently the only Food and Drug Administration-approved treatment for ALS, but its effect on survival is modest. OBJECTIVE: To identify potential neuroprotective agents for testing in phase III clinical trials and to outline which data need to be collected for each drug. METHODS: The authors identified 113 compounds by inviting input from academic clinicians and researchers and via literature review to identify agents that have been tested in ALS animal models and in patients with ALS. The list was initially narrowed to 24 agents based on an evaluation of scientific rationale, toxicity, and efficacy in previous animal and human studies. These 24 drugs underwent more detailed pharmacologic evaluation. RESULTS: Twenty drugs were selected as suitable for further development as treatments for patients with ALS. Talampanel and tamoxifen have completed early phase II trials and have demonstrated preliminary efficacy. Other agents (ceftriaxone, minocycline, ONO-2506, and IGF-1 polypeptide) are already in phase III trials involving large numbers of patients with ALS. Remaining agents (AEOL 10150, arimoclomol, celastrol, coenzyme Q10, copaxone, IGF-1-viral delivery, memantine, NAALADase inhibitors, nimesulide, scriptaid, sodium phenylbutyrate, thalidomide, trehalose) require additional preclinical animal data, human toxicity and pharmacokinetic data including CNS penetration prior to proceeding to large scale phase III human testing. Further development of riluzole analogues should be considered. CONCLUSIONS: Several potential neuroprotective compounds, representing a wide range of mechanisms, are available and merit further investigation in ALS.

Identification of potential CSF biomarkers in ALS.

BACKGROUND: The clinical diagnosis of ALS is based entirely on clinical features. Identification of biomarkers for ALS would be important for diagnosis and might also provide clues to pathogenesis. OBJECTIVE: To determine if there is a specific protein profile in the CSF that distinguishes patients with ALS from those with purely motor peripheral neuropathy (PN) and healthy control subjects. METHODS: CSF obtained from patients with ALS, disease controls (patients with other neurologic disorders), and normal controls were analyzed using the surface-enhanced laser desorption/ionization time-of-flight mass spectrometry proteomics technique. Biomarker sensitivity and specificity was calculated with receiver operating characteristic curve methodology. ALS biomarkers were purified and sequence identified by mass spectrometry-directed peptide sequencing. RESULTS: In initial proteomic discovery studies, three protein species (4.8-, 6.7-, and 13.4-kDa) that were significantly lower in concentration in the CSF from patients with ALS (n = 36) than in normal controls (n = 21) were identified. A combination of three protein species (the "three-protein" model) correctly identified patients with ALS with 95% accuracy, 91% sensitivity, and 97% specificity from the controls. Independent validation studies using separate cohorts of ALS (n = 13), healthy control (n = 25), and PN (n = 7) subjects confirmed the ability of the three CSF protein species to separate patients with ALS from other diseases. Protein sequence analysis identified the 13.4-kDa protein species as cystatin C and the 4.8-kDa protein species as a peptic fragment of the neurosecretory protein VGF. CONCLUSION: Additional application of a "three-protein" biomarker model to current diagnostic criteria may provide an objective biomarker pattern to help identify patients with ALS.

Detection of serum reverse transcriptase activity in patients with ALS and unaffected blood relatives.

BACKGROUND: Retroviral involvement in the etiology of sporadic ALS has been suspected for several years since the recognition that both murine and human retroviruses can cause motor neuron disease-like syndromes. In a pilot study, an increased prevalence of a retroviral marker (reverse transcriptase [RT] activity) was demonstrated in the serum of British patients with ALS. The current investigation was designed to confirm and extend these findings in a geographically distinct patient cohort under blinded testing conditions. METHODS: A highly sensitive product-enhanced RT assay was employed to test coded sera obtained from 30 American patients with sporadic ALS and from 14 of their blood relatives, 16 of their spouses, and 28 nonrelated, nonspousal control subjects. RESULTS: Serum RT activity was detected in a higher proportion of ALS patients (47%) than in non-blood-related controls (18%; p = 0.008). The prevalence of RT activity in the serum of spousal controls (13%) was similar to that in other non-blood-related controls. Unexpectedly, the prevalence of serum RT activity in blood relatives of ALS patients (43%) approached that in the ALS patients themselves. CONCLUSIONS: These results confirm that patients with ALS have a significantly higher prevalence of serum reverse transcriptase (RT) activity than that seen in unrelated control subjects. The finding of a similarly increased prevalence in blood relatives of ALS patients raises the possibility that the observed RT activity might be due to an inherited endogenous retrovirus.

A clinical trial of creatine in ALS.

BACKGROUND: Mitochondrial dysfunction occurs early in the course of ALS, and the mitochondria may be an important site for therapeutic intervention. Creatine stabilizes the mitochondrial transition pore, and is important in mitochondrial ATP production. In a transgenic mouse model of ALS, administration of creatine prolongs survival and preserves motor function and motor neurons. METHODS: The authors conducted a randomized double-blind, placebo controlled trial on 104 patients with ALS from 14 sites to evaluate the efficacy of creatine supplementation in ALS. The primary outcome measure was maximum voluntary isometric contraction of eight upper extremity muscles, with secondary outcomes including grip strength, ALS Functional Rating Scale-Revised, and motor unit number estimates. Patients were treated for 6 months, and evaluated monthly. RESULTS: Creatine was tolerated well, but no benefit of creatine could be demonstrated in any outcome measure. CI analysis showed that the study, although powered to detect a 50% or greater change in rate of decline of muscle strength, actually made an effect size of greater than 23% unlikely. It was also demonstrated that motor unit number estimation was performed with acceptable reproducibility and tolerability, and may be a useful outcome measure in future clinical trials. CONCLUSION: Any beneficial effect of creatine at 5 g per day in ALS must be small. Other agents should be considered in future studies of therapeutic agents to address mitochondrial dysfunction in ALS. In addition, motor unit number estimation may be a useful outcome measure for future clinical trials in ALS.

Functional outcome measures as clinical trial endpoints in ALS.

The topiramate study was a 12-month randomized placebo-controlled trial in patients with ALS. Follow-up evaluation of the placebo group (n = 97) constituted a well-described cohort of patients with ALS, in whom multiple outcome measures were assessed at 3-month intervals. During the 12-month study period, the decline of forced vital capacity (FVC%) and ALS functional rating scale (ALSFRS) was linear, whereas the decline of maximum voluntary isometric contraction-arm (MVIC-arm) and MVIC-grip Z scores was curvilinear. Rates of FVC% and ALFRS decline, but not of MVIC-arm or MVIC-grip, were independent predictors of survival.

The use of statistical MUNE in a multicenter clinical trial.

Techniques to estimate motor unit number (MUNE) measure the number of functioning motor units in a muscle. In diseases characterized by progressive motor unit loss, such as amyotrophic lateral sclerosis (ALS), MUNE may be useful to monitor disease progression or beneficial response to treatment. As part of a multicenter, placebo-controlled, randomized, double-blind clinical trial testing the efficacy of creatine in patients with ALS, statistical MUNE was measured in 104 patients tested monthly for 6 months. The objective was to determine whether MUNE was a reliable and sensitive outcome measure in the context of a multicenter trial. Formal training and reliability testing was required for all MUNE evaluators. Testing of normal controls showed a high degree of test-retest reliability. All patient data were combined as the experimental treatment showed no efficacy. There was a 23% decline in MUNE over 6 months. The technique as employed in this trial overemphasized the presence of small motor units; this problem was partially addressed by poststudy data monitoring and censuring. Thus, MUNE can be used reliably as an outcome measure in multicenter clinical trials; specific remedies are suggested for the difficulties encountered in this study.

A randomized, placebo-controlled trial of topiramate in amyotrophic lateral sclerosis.

OBJECTIVE: To determine if long-term topiramate therapy is safe and slows disease progression in patients with ALS. METHODS: A double-blind, placebo-controlled, multicenter randomized clinical trial was conducted. Participants with ALS (n = 296) were randomized (2:1) to receive topiramate (maximum tolerated dose up to 800 mg/day) or placebo for 12 months. The primary outcome measure was the rate of change in upper extremity motor function as measured by the maximum voluntary isometric contraction (MVIC) strength of eight arm muscle groups. Secondary endpoints included safety and the rate of decline of forced vital capacity (FVC), grip strength, ALS functional rating scale (ALSFRS), and survival. RESULTS: Patients treated with topiramate showed a faster decrease in arm strength (33.3%) during 12 months (0.0997 vs 0.0748 unit decline/month, p = 0.012). Topiramate did not significantly alter the decline in FVC and ALSFRS or affect survival. Topiramate was associated with an increased frequency of anorexia, depression, diarrhea, ecchymosis, nausea, kidney calculus, paresthesia, taste perversion, thinking abnormalities, weight loss, and abnormal blood clotting (pulmonary embolism and deep venous thrombosis). CONCLUSIONS: At the dose studied, topiramate did not have a beneficial effect for patients with ALS. High-dose topiramate treatment was associated with a faster rate of decline in muscle strength as measured by MVIC and with an increased risk for several adverse events in patients with ALS. Given the lack of efficacy and large number of adverse effects, further studies of topiramate at a dose of 800 mg or maximum tolerated dose up to 800 mg/day are not warranted.

Evidence for more widespread cerebral pathology in early HD: an MRI-based morphometric analysis.

BACKGROUND: Most clinical symptoms of Huntington disease (HD) have been attributed to striatal degeneration, but extrastriatal degeneration may play an important role in the clinical symptoms because postmortem studies demonstrate that almost all brain structures atrophy. OBJECTIVE: To fully characterize the morphometric changes that occur in vivo in HD. METHODS: High-resolution 1.5 mm T1-weighted coronal scans were acquired from 18 individuals in early to mid-stages of HD and 18 healthy age-matched controls. Cortical and subcortical gray and white matter were segmented using a semiautomated intensity contour-mapping algorithm. General linear models for correlated data of the volumes of brain regions were used to compare groups, controlling for age, education, handedness, sex, and total brain volumes. RESULTS: Subjects with HD had significant volume reductions in almost all brain structures, including total cerebrum, total white matter, cerebral cortex, caudate, putamen, globus pallidus, amygdala, hippocampus, brainstem, and cerebellum. CONCLUSIONS: Widespread degeneration occurs in early to mid-stages of HD, may explain some of the clinical heterogeneity, and may impact future clinical trials.

Tissue inhibitors of matrix metalloproteinases are elevated in cerebrospinal fluid of neurodegenerative diseases.

Matrix metalloproteinases (MMPs) are implicated in the pathogenesis of diseases such as Alzheimer's Disease (AD) and amyotrophic lateral sclerosis (ALS). Increased expression of MMP-9 and TIMPs has been reported in postmortem AD and ALS brain tissue, as well as in ALS cerebrospinal fluid (CSF) and plasma. Although individual studies of MMP and TIMP expression in CSF have included AD and ALS samples, there are no studies comparing the expression of these proteins between neurodegenerative diseases. We measured the levels of matrix metalloproteinases (MMPs)-2 and -9 and the tissue inhibitor of MMPs (e.g. TIMP-1 and TIMP-2) in CSF samples from patients with Parkinson's Disease (PD), Huntington's Disease (HD), AD and ALS as compared to age-matched control patients. There was constitutive expression of the proform of gelatinase A (proMMP-2) on zymography gels in all CSF samples. Unexpectedly, there was an additional gelatinolytic band at 130 kDa of unknown etiology in the CSF samples of patients with PD (61% of patients studied), AD (61%), HD (25%) and ALS (39%). Levels of TIMP-1 were significantly elevated in CSF samples from all disease groups. TIMP-2 was significantly increased in CSF of AD and HD patients. MMP-2 levels did not differ significantly between groups. These findings show that TIMPs are elevated in the CSF of patients with neurodegenerative diseases suggesting a potential role of these endogenous inhibitors of matrix metalloproteinases in neurodegenerative diseases.

Survival in transgenic ALS mice does not vary with CNS glutathione peroxidase activity.

OBJECTIVE: Transgenic mice that overexpress a human gene encoding mutant cytosolic superoxide dismutase (SOD1) develop a progressive motor neuron loss that resembles human ALS. Why mutant SOD1 initiates motor neuron death is unknown. One hypothesis proposes that the mutant molecule has enhanced peroxidase activity, reducing hydrogen peroxide (H2O2) to form toxic hydroxyl adducts on critical targets. To test this hypothesis, the authors generated transgenic ALS mice with altered levels of glutathione peroxidase (GSHPx), the major soluble enzyme that detoxifies H2O2. METHODS: SOD1(G93A) ALS mice were bred with mice bearing a murine GSHPx transgene that have a four-fold elevation in brain GSHPx levels and with mice having targeted inactivation of the GSHPx gene and reduced brain GSHPx activity. RESULTS: Survival was not prolonged in ALS mice with elevated brain GSHPx activity (p = 0.09). ALS mice with decreased GSHPx brain activity (20% of normal) showed no acceleration of the disease course (p = 0.89). The age at disease onset in the ALS mice was unaffected by brain GSHPx activity. CONCLUSION: The level of GSHPx activity in the CNS of transgenic ALS mice does not play a critical role in the development of motor neuron disease.

Effect of neurophilin ligands on motor units in mice with SOD1 ALS mutations.

BACKGROUND: Mice with trangenes that express mutations in the gene for cytosolic copper/zinc superoxide dismutase (SOD1) develop motor neuron degeneration resembling human ALS. Neurophilin ligands are small molecules that promote neurite outgrowth. OBJECTIVE: To test the hypothesis that treatment with two neurophilin ligands increases survival in these ALS mice by slowing the loss of motor neurons and increasing the sizes of motor units. METHODS: Transgenic mice hemizygous for the G93A mutation were untreated or treated from 30 days of age with one of two doses of two neurophilin ligands (V-13,670; V-10,367, Vertex Pharmaceuticals, Boston, MA). Onset of behavioral abnormalities and survival were recorded. Motor unit number estimation (MUNE) was performed every 21 days starting at age 60 days. RESULTS: In control animals, disease onset occurred at 77.0 days of age and death occurred at 137 days of age. Neither neurophilin ligand affected the disease course. In control animals, MUNE declined with time beginning before behavioral abnormalities were noted, and motor unit size increased concomitantly. There was no effect of drug on motor unit loss as assessed by MUNE; however, motor unit size increased more rapidly and to a greater degree in animals treated with V-13,670. CONCLUSION: As in human ALS, the transgenic ALS mice show physiologic changes in the motor unit prior to the development of clinical signs: MUNE declines as motor unit size increases. Although neither neurophilin ligand significantly affected survival, one produced an increase in motor unit size. The fact that survival was not altered by the increase in motor unit size may reflect the rapid disease course in this animal model.

Clozapine and risperidone treatment of psychosis in Parkinson's disease.

The authors compared efficacy and safety of risperidone and clozapine for the treatment of psychosis in a double-blind trial with 10 subjects with Parkinson's disease (PD) and psychosis. Mean improvement in the Brief Psychiatric Rating Scale psychosis score was similar in the clozapine and the risperidone groups (P=0.23). Although the mean motor Unified Parkinson's Disease Rating Scale score worsened in the risperidone group and improved in the clozapine group, this difference did not reach statistical significance. One subject on clozapine developed neutropenia. In subjects with PD, risperidone may be considered as an alternative to clozapine because it is as effective for the treatment of psychoses without the hematologic, antimuscarinic, and seizure side effects. However, risperidone may worsen extrapyramidal symptoms more than clozapine and therefore must be used with caution.

Dynamic markers of altered gait rhythm in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a disorder marked by loss of motoneurons. We hypothesized that subjects with ALS would have an altered gait rhythm, with an increase in both the magnitude of the stride-to-stride fluctuations and perturbations in the fluctuation dynamics. To test for this locomotor instability, we quantitatively compared the gait rhythm of subjects with ALS with that of normal controls and with that of subjects with Parkinson's disease (PD) and Huntington's disease (HD), pathologies of the basal ganglia. Subjects walked for 5 min at their usual pace wearing an ankle-worn recorder that enabled determination of the duration of each stride and of stride-to-stride fluctuations. We found that the gait of patients with ALS is less steady and more temporally disorganized compared with that of healthy controls. In addition, advanced ALS, HD, and PD were associated with certain common, as well as apparently distinct, features of altered stride dynamics. Thus stride-to-stride control of gait rhythm is apparently compromised with ALS. Moreover, a matrix of markers based on gait dynamics may be useful in characterizing certain pathologies of motor control and, possibly, in quantitatively monitoring disease progression and evaluating therapeutic interventions.