Intercellular transmission of pathogenic proteins in ALS: Exploring the pathogenic wave.

In patients with amyotrophic lateral sclerosis (ALS), disease symptoms and pathology typically spread in a predictable spatiotemporal pattern beginning at a focal site of onset and progressing along defined neuroanatomical tracts. Like other neurodegenerative diseases, ALS is characterized by the presence of protein aggregates in postmortem patient tissue. Cytoplasmic, ubiquitin-positive aggregates of TDP-43 are observed in approximately 97% of sporadic and familial ALS patients, while SOD1 inclusions are likely specific to cases of SOD1-ALS. Additionally, the most common subtype of familial ALS, caused by a hexanucleotide repeat expansion in the first intron of the C9orf72 gene (C9-ALS), is further characterized by the presence of aggregated dipeptide repeat proteins (DPRs). As we will describe, cell-to-cell propagation of these pathological proteins tightly correlates with the contiguous spread of disease. While TDP-43 and SOD1 are capable of seeding protein misfolding and aggregation in a prion-like manner, C9orf72 DPRs appear to induce (and transmit) a 'disease state' more generally. Multiple mechanisms of intercellular transport have been described for all of these proteins, including anterograde and retrograde axonal transport, extracellular vesicle secretion, and macropinocytosis. In addition to neuron-to-neuron transmission, transmission of pathological proteins occurs between neurons and glia. Given that the spread of ALS disease pathology corresponds with the spread of symptoms in patients, the various mechanisms by which ALS-associated protein aggregates propagate through the central nervous system should be closely examined.

Lunasin does not slow ALS progression: results of an open-label, single-center, hybrid-virtual 12-month trial.

Objective: Lunasin, a soy peptide that reportedly alters histone acetylation in vitro, was associated with a single ALS reversal in the media. Following an ALSUntangled report, we sought to determine whether Lunasin altered histone acetylation and improved progression in people with ALS, and whether patient-centric trial design features might improve enrollment and retention. Methods: This single-center, year-long trial (NCT02709330) featured broad inclusion criteria, historical controls, primarily virtual data collection, and real-time results. Participants measured their own ALSFRS-R score, weight and perceived efficacy, and recorded these monthly on PatientsLikeMe. Blood tests at screening and month 1 assessed alterations in histone H3 and H4 acetylation. The protocol was published online, empowering patients outside the study to self-experiment. Results: Fifty participants enrolled in 5.5 months. Although this population had more advanced disease compared to other trials, retention and adherence were very high. There was no significant effect of Lunasin treatment on histone acetylation or disease progression. A cohort following our protocol outside the trial reported similar side effects and perceived effectiveness; however, their compliance with data entry was markedly lower. Conclusions: While Lunasin's lack of efficacy is disappointing, our novel trial design had the highest ALS trial enrollment rate ever recorded, with excellent retention and adherence. Low data density from patients who are self-experimenting outside a formal protocol casts doubt on the possibility of gathering useful information from unsupervised expanded access programs or "right to try" initiatives.

The National Registry of Veterans with amyotrophic lateral sclerosis.

BACKGROUND: The Department of Veterans Affairs (VA) Cooperative Studies Program has established a National Registry of Veterans with Amyotrophic Lateral Sclerosis (ALS). This article describes the objectives, methods, and sample involved in the registry. METHODS: United States military veterans with ALS were identified through national VA electronic medical record databases and nationwide publicity efforts for an enrollment period of 4 1/2 years. Diagnoses were confirmed by medical record reviews. Registrants were asked to participate in a DNA bank. Follow-up telephone interviews are conducted every 6 months to track participants' health status. RESULTS: As of September 30, 2007, 2,400 veterans had consented to participate in the registry, 2,068 were included after medical record review, 995 were still living and actively participating, and 1,573 consented to participate in the DNA bank. 979 participants had been enrolled in the registry for at least 1 year, 497 for at least 2 years, and 205 for at least 3 years. Fourteen studies have been approved to use registry data for epidemiological, observational, and interventional protocols. CONCLUSION: This registry has proven to be a successful model for identifying large numbers of patients with a relatively rare disease and enrolling them into multiple studies, including genetic protocols.

Quantitative myasthenia gravis score: assessment of responsiveness and longitudinal validity.

We prospectively tested the quantitative myasthenia gravis score (QMG) for responsiveness and longitudinal construct validity in 53 patients with myasthenia gravis. Index of responsiveness was high. Longitudinal construct validity was confirmed by the correlation between changes in QMG and manual muscle testing and by a difference in QMG changes across patients that were clinically unchanged, improved, or worse between two visits. Our results support QMG use for assessing clinical change in trials.

APOE genotype is a risk factor for neuropathy severity in diabetic patients.

This cross-sectional study tested the hypothesis that APOE genotype is a risk factor for diabetic neuropathy severity. A model with age, duration of diabetes, and APOE genotype was found to predict (p = 0.0083) severity on the Neuropathy Impairment Score in the Lower Limbs (NISLL). Considering genotype alone, patients with APOE 3/4 and 4/4 genotypes had 3 more NISLL points than patients with other genotypes. This impact on severity is equivalent to having 15 extra years of age or diabetes duration.

Apolipoprotein E and neuromuscular disease: a critical review of the literature.

Molecular mechanisms that alter the incidence and rate of neuromuscular disease progression are, in many cases, only partially understood. Several recent studies have asked whether apolipoprotein E (apoE for the protein, APOE for the gene) influences these aspects of specific neuromuscular disorders, as it does in central nervous system disorders such as Alzheimer disease. Although these studies are open to methodological criticism, several interesting trends have emerged. First, the APOE4 allele seems to be associated with an increased risk for developing certain neuromuscular diseases, including diabetic neuropathy and human immunodeficiency viral neuropathy. Second, this allele appears to be associated with faster progression of some neuromuscular diseases, including diabetic neuropathy and possibly motor neuron disease. Third, the APOE2 allele seems to confer protection against developing certain neuromuscular diseases, including the amyotrophic lateral sclerosis (ALS)/parkinsonism/dementia complex of Guam. Finally, this allele is associated with a better prognosis in neuromuscular diseases such as motor neuron disease. The effect of various APOE alleles on neuromuscular diseases therefore parallels their influence on central nervous system diseases. Arch Neurol. 2000;57:1561-1565

How to handle myasthenic crisis. Essential steps in patient care.

Myasthenic crisis, or respiratory failure requiring intubation and mechanical ventilation, may be caused by infections, aspiration, physical and emotional stress, and changes in medication. Although no single factor determines the need for respiratory support, all patients with questionable respiratory status should be admitted to the ICU. Because management of crisis includes treatment of the underlying myasthenia gravis, a neurologist should share in any decisions regarding care.

Hidden afterdischarges in slow channel congenital myasthenic syndrome.

Afterdischarges in motor nerve stimulation studies help distinguish slow channel congenital myasthenic syndrome (SCCMS) from acquired myasthenia gravis (MG) We present a patient with fatigable weakness in whom afterdischarges were not initially apparent. After she failed to respond to treatment for MG, afterdischarges were demonstrated in some, but not all, of her muscles. Genetic testing confirmed SCCMS. This case indicates that electrophysiological distinction between SCCMS and MG may require motor nerve stimulation studies in multiple muscles.

Transient lumbosacral polyradiculopathy after prostatectomy: association with spinal stenosis.

Mononeuropathies are common after pelvic surgery. They are usually the result of unnatural positioning during surgery or faulty restraining devices. Polyneuropathy in the postoperative setting is rare. We report two cases of polyradiculopathy after radical prostatectomy using two different patient positions. Both patients complained of paresthesias and weakness in their lower extremities on postoperative day 1. Neurologic examination in each case was consistent with a polyradiculopathy. Significant spinal stenosis of the lumbosacral spine was found in both patients by magnetic resonance imaging. We propose that spinal stenosis is a risk factor for this type of neurologic injury.

Succinylcholine induced hyperkalemia and cardiac arrest death related to an EEG study.

Changes in EEGs during cardiac arrest have been described in detail by many authors; however, mortality because of an EEG has never been reported. The authors report the case of a patient who developed cardiac arrest causally related to administration of succinylcholine for reduction of excessive amounts of myogenic artifact during an EEG. This case indicates the need for caution when doing an EEG study in an intensive care unit setting.

Distinct electric potentials in soma and neurite membranes.

Structurally similar voltage-dependent ion channels may behave differently in different locations along the surface of a neuron. A possible reason could be that channels experience nonuniform electrical potentials along the plasmalemma. Here, we map the electrical potentials along the membrane of differentiated N1E-115 neuroblastoma cells with a potential-sensitive dye. We find that the intramembrane potential gradient is indeed more positive in the membranes of neurites than in the membranes of somata. This is not attributable to differences in ion conductances or surface charge densities between the membranes of neurites and somata; instead, it can be explained by differences in lipid composition. The spatial variation in intramembrane electrical potential may help account for electrophysiological and functional differences between neurites and somata.

Dual-wavelength ratiometric fluorescence measurement of the membrane dipole potential.

The electrostatic potentials associated with cell membranes include the transmembrane potential (delta psi), the surface potential (psi s), and the dipole potential (psi D). psi D, which originates from oriented dipoles at the surface of the membrane, rises steeply just within the membrane to approximately 300 mV. Here we show that the potential-sensitive fluorescent dye 1-(3-sulfonatopropyl)-4-[beta[2-(di-n-octylamino)-6- naphthyl]vinyl]pyridinium betaine (di-8-ANEPPS) can be used to measure changes in the intramembrane dipole potential. Increasing the content of cholesterol and 6-ketocholestanol (KC), which are known to increase psi D in the bilayer, results in an increase in the ratio, R, of the dye fluorescence excited at 440 nm to that excited at 530 nm in a lipid vesicle suspension; increasing the content of phloretin, which lowers psi D, decreases R. Control experiments show that the ratio is insensitive to changes in the membrane's microviscosity. The lack of an isosbestic point in the fluorescence excitation and emission spectra of the dye at various concentrations of KC and phloretin argues against 1:1 chemical complexation between the dye and KC or phloretin. The macromolecular nonionic surfactant Pluronic F127 catalyzes the insertion of KC and phloretin into lipid vesicle and cell membranes, permitting convenient and controlled modulation of dipole potential. The sensitivity of R to psi D is 10-fold larger than to delta psi, whereas it is insensitive to changes in psi S. This can be understood in terms of the location of the dye chromophore with respect to the electric field profile associated with each of these potentials. These results suggest that the gradient in dipole potential occurs over a span s5 A, a short distance below the membrane-water interface. These approaches are easily adaptable to study the influence of dipole potentials on cell membrane physiology.

Localized membrane depolarizations and localized calcium influx during electric field-guided neurite growth.

Our study explores the mechanisms behind neurite galvanotropism. Using phase, differential interference contrast and ratiometric fluorescence microscopy, we reveal four responses of N1E-115 mouse neuroblastoma cells to 0.1-1.0 mV/microns uniform DC electric fields: cathode-directed neurite initiation and elongation, cathode-biased growth cone filopodial protrusions, transient cathode-localized calcium increases, and persistent cathode-localized membrane depolarizations. These newly demonstrated events are temporally and spatially correlated, suggesting that they are causally related. The calcium increases are prevented by calcium channel blockers and by the removal of extracellular calcium. We therefore propose that the observed field-induced membrane depolarizations activate voltage-dependent calcium channels, resulting in cathode-localized calcium influx. This, in turn, may initiate the observed cathode-biased growth cone filopodial protrusions, followed by the cathode-directed neurite elongation.