Acute Intermittent Hypoxia With High-Intensity Gait Training in Chronic Stroke: A Phase II Randomized Crossover Trial.

BACKGROUND: Studies in individuals with chronic stroke indicate high-intensity training (HIT) focused on walking improves locomotor function, which may be due to repeated activation of locomotor circuits and serotonin-dependent modulation of motor output. Separate studies in animals and individuals with spinal cord injury suggest acute intermittent hypoxia (AIH) can augment the effects of locomotor interventions through similar serotonin-dependent mechanisms, although no studies have coupled AIH with HIT in individuals poststroke. The goal of this study was to evaluate the safety and efficacy of AIH+HIT versus HIT alone in individuals with chronic stroke. METHODS: This phase II double-blind randomized, crossover trial recruited individuals between 18 and 85 years old, >6 months poststroke, and self-selected speeds <1.0 m/s. Participants received up to 15 sessions of AIH for 30 minutes using 15 cycles of hypoxia (60-90 seconds; 8%-9% O2) and normoxia (30-60 seconds; 21% O2), followed by 1 hour of HIT targeting >75% heart rate reserve. The control condition received normoxia for 30 minutes before HIT. Following the first training phase, participants performed the second phase >1 month later. The primary outcomes were self-selected speed and fastest speed, a 6-minute walk test, and peak treadmill speed. A 3-way mixed-model ANOVA assessed the effects of time, training, and order of interventions. RESULTS: Of 55 individuals screened, 35 were randomized to AIH+HIT or normoxia+HIT first, and 28 individuals completed both interventions, revealing greater gains in self-selected speeds (0.14 [0.08-0.18] versus 0.05 [0.01-0.10] m/s), fastest speed (0.16 [0.10-0.21] versus 0.06 [0.02-0.10] m/s), and peak treadmill speed (0.21 [0.14-0.29] versus 0.11 [0.06-0.16] m/s) following AIH+HIT versus normoxia+HIT (P<0.01) with no order effects. Greater gains in spatiotemporal symmetry were observed with AIH+HIT, with worse outcomes for those prescribed serotonin-mediated antidepressant medications. CONCLUSIONS: AIH+HIT resulted in greater gains in locomotor function than normoxia+HIT. Subsequent phase III trials should further evaluate the efficacy of this intervention. REGISTRATION: URL: https://clinicaltrials.gov/; Unique identifier: NCT04472442.

Increasing Activity After Stroke: A Randomized Controlled Trial of High-Intensity Walking and Step Activity Intervention.

BACKGROUND: Physical inactivity in people with chronic stroke profoundly affects daily function and increases recurrent stroke risk and mortality, making physical activity improvements an important target of intervention. We compared the effects of a high-intensity walking intervention (FAST), a step activity monitoring behavioral intervention (SAM), or a combined intervention (FAST+SAM) on physical activity (ie, steps/day). We hypothesized the combined intervention would yield the greatest increase in steps/day. METHODS: This assessor-blinded multisite randomized controlled trial was conducted at 4 university/hospital-based laboratories. Participants were 21 to 85 years old, walking without physical assistance following a single, unilateral noncerebellar stroke of ≥6 months duration, and randomly assigned to FAST, SAM, or FAST+SAM for 12 weeks (2-3 sessions/week). FAST training consisted of walking-related activities at 70% to 80% heart rate reserve, while SAM received daily feedback and goal setting of walking activity (steps/day). Assessors and study statistician were masked to group assignment. The a priori-determined primary outcome and end point was a comparison of the change in steps/day between the 3 intervention groups from pre- to post-intervention. Adverse events were tracked after randomization. All randomized participants were included in the intent-to-treat analysis. RESULTS: Participants were enrolled from July 18, 2016, to November 16, 2021. Of 2385 participants initially screened, 250 participants were randomized (mean [SE] age, 63 [0.80] years; 116 females/134 males), with 89 assigned to FAST, 81 to SAM, and 80 to FAST+SAM. Steps/day significantly increased in both the SAM (mean [SE], 1542 [267; 95% CI, 1014-2069] P<0.001) and FAST+SAM group (1307 [280; 95% CI, 752-1861] P<0.001) but not in the FAST group (406 [238; 95% CI, -63 to 876] P=0.09). There were no deaths or serious study-related adverse events. CONCLUSIONS: Only individuals with chronic stroke who completed a step activity monitoring behavioral intervention with skilled coaching and goal progression demonstrated improvements in physical activity (steps/day). REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02835313.

In vivo genome editing using novel AAV-PHP variants rescues motor function deficits and extends survival in a SOD1-ALS mouse model.

CRISPR-based gene editing technology represents a promising approach to deliver therapies for inherited disorders, including amyotrophic lateral sclerosis (ALS). Toxic gain-of-function superoxide dismutase 1 (SOD1) mutations are responsible for ~20% of familial ALS cases. Thus, current clinical strategies to treat SOD1-ALS are designed to lower SOD1 levels. Here, we utilized AAV-PHP.B variants to deliver CRISPR-Cas9 guide RNAs designed to disrupt the human SOD1 (huSOD1) transgene in SOD1G93A mice. A one-time intracerebroventricular injection of AAV.PHP.B-huSOD1-sgRNA into neonatal H11Cas9 SOD1G93A mice caused robust and sustained mutant huSOD1 protein reduction in the cortex and spinal cord, and restored motor function. Neonatal treatment also reduced spinal motor neuron loss, denervation at neuromuscular junction (NMJ) and muscle atrophy, diminished axonal damage and preserved compound muscle action potential throughout the lifespan of treated mice. SOD1G93A treated mice achieved significant disease-free survival, extending lifespan by more than 110 days. Importantly, a one-time intrathecal or intravenous injection of AAV.PHP.eB-huSOD1-sgRNA in adult H11Cas9 SOD1G93A mice, immediately before symptom onset, also extended lifespan by at least 170 days. We observed substantial protection against disease progression, demonstrating the utility of our CRISPR editing preclinical approach for target evaluation. Our approach uncovered key parameters (e.g., AAV capsid, Cas9 expression) that resulted in improved efficacy compared to similar approaches and can also serve to accelerate drug target validation.

Predicting Discharge Walking Function With High-Intensity Stepping Training During Inpatient Rehabilitation in Nonambulatory Patients Poststroke.

OBJECTIVE: This cohort investigation identified primary predictors of discharge walking function of nonambulatory individuals poststroke with high-intensity training (HIT) during inpatient rehabilitation. DESIGN: Observational cohort investigation. SETTING: Inpatient rehabilitation. PARTICIPANTS: Data were collected from individuals (N=257) <6 months poststroke who required assistance to walk at admission. INTERVENTION: Clinical physical therapy interventions attempted to maximize stepping practice at higher intensities. MAIN OUTCOME MEASURES: Primary outcomes included the discharge level of assistance required during walking (minimal or no assistance) and attainment of specific gait speed thresholds (0.4 and 0.8 m/s) during the 10-m walk test. Independent predictors were demographics, training interventions (including steps/day), baseline Berg Balance Scale (BBS), and paretic leg strength. RESULTS: Participants performed a median (interquartile range) of 1270 (533-2297) steps per day throughout inpatient rehabilitation, with significant differences between those who walked with versus without assistance at discharge. Logistic regressions indicate steps per day was a primary predictor of unassisted walking recovery; removal of steps per day resulted in primary predictors of baseline BBS and strength. Receiver operating characteristic (ROC) analyses indicate significant areas under the curve for BBS and relatively low cutoff scores of 5.5 points at admission to walk without assistance at any speed. ROC analyses performed using 1-week outcomes indicate BBS scores of 5-17 points were needed to achieve locomotor thresholds. CONCLUSION: Stepping activity, BBS, and paretic leg strength were primary predictors of walking outcomes in patients performing HIT, and ROC analyses indicated recovery of independent walking could be achieved in low functioning patients early poststroke.

The Value of High Intensity Locomotor Training Applied to Patients With Acute-Onset Neurologic Injury.

Long-standing research in animal models and humans with stroke or incomplete spinal cord injury (iSCI) indicate that specific physical training variables, such as the specificity and amount of practice, may influence neurologic recovery and locomotor function. More recent data highlight the contributions of exercise intensity, as estimated indirectly by cardiovascular exertion, as potentially more important than previously considered. The effects of exercise intensity are well described in neurologically intact individuals, although confusion regarding the definitions of intensity and safety concerns have limited its implementation during physical rehabilitation of patients with neurologic injury. The purpose of this review is to delineate some of the evidence regarding the effects of exercise intensity during locomotor training in patients with stroke and iSCI. We provide specific definitions of exercise intensity used within the literature, describe methods used to ensure appropriate levels of exertion, and discuss potential adverse events and safety concerns during its application. Further details on the effects of locomotor training intensity on clinical outcomes, and on neuromuscular and cardiovascular function will be addressed as available. Existing literature across multiple studies and meta-analyses reveals that exercise training intensity is likely a major factor that can influence locomotor function after neurologic injury. To extend these findings, we describe previous attempts to implement moderate to high intensity interventions during physical rehabilitation of patients with neurologic injury, including the utility of specific strategies to facilitate implementation, and to navigate potential barriers that may arise during implementation efforts.

Use of CRISPR/Cas9-mediated disruption of CNS cell type genes to profile transduction of AAV by neonatal intracerebroventricular delivery in mice.

Adeno-associated virus (AAV) transduction efficiency and tropism are conventionally determined by high expression of a fluorescent reporter gene. Emerging data has suggested that such conventional methods may underestimate AAV transduction for cells in which reporter expression from AAV vectors is undetectable. To explore an alternative method that captures AAV transduction in cells in which low expression of a cargo is sufficient for the intended activity, we sought after CRISPR/Cas9-mediated gene disruption. In this study, we use AAV to deliver CRISPR/guide RNA designed to abolish the genes NeuN, GFAP, or MOG expressed specifically in neurons, astrocytes, or oligodendrocytes respectively in the central nervous system (CNS) of mice. Abrogated expression of these cell-type-specific genes can be measured biochemically in CNS subregions and provides quantitative assessment of AAV transduction in these CNS cell types. By using this method, we compared CNS transduction of AAV9, AAV-PHP.B, and AAV-PHP.eB delivered via intracerebroventricular injection (ICV) in neonatal mice. We found both AAV-PHP.B and AAV-PHP.eB resulted in marked disruption of the NeuN gene by CRISPR/Cas9, significantly greater than AAV9 in several brain regions and spinal cord. In contrast, only modest disruption of the GFAP gene and the MOG gene was observed by all three AAV variants. Since the procedure of ICV circumvents the blood-brain barrier, our data suggests that, independent of their ability to cross the blood-brain barrier, AAV-PHP.B variants also exhibit remarkably improved neuronal transduction in the CNS. We anticipate this approach will facilitate profiling of AAV cellular tropism in murine CNS.

Stepwise Regression and Latent Profile Analyses of Locomotor Outcomes Poststroke.

BACKGROUND AND PURPOSE: Previous data suggest patient demographics and clinical presentation are primary predictors of motor recovery poststroke, with minimal contributions of physical interventions. Other studies indicate consistent associations between the amount and intensity of stepping practice with locomotor outcomes. The goal of this study was to determine the relative contributions of these combined variables to locomotor outcomes poststroke across a range of patient demographics and baseline function. METHODS: Data were pooled from 3 separate trials evaluating the efficacy of high-intensity training, low-intensity training, and conventional interventions. Demographics, clinical characteristics, and training activities from 144 participants >1-month poststroke were included in stepwise regression analyses to determine their relative contributions to locomotor outcomes. Subsequent latent profile analyses evaluated differences in classes of participants based on their responses to interventions. RESULTS: Stepwise regressions indicate primary contributions of stepping activity on locomotor outcomes, with additional influences of age, duration poststroke, and baseline function. Latent profile analyses revealed 2 main classes of outcomes, with the largest gains in those who received high-intensity training and achieved the greatest amounts of stepping practice. Regression and latent profile analyses of only high-intensity training participants indicated age, baseline function, and training activities were primary determinants of locomotor gains. Participants with the smallest gains were older (≈60 years), presented with slower gait speeds (<0.40 m/s), and performed 600 to 1000 less steps/session. CONCLUSIONS: Regression and cluster analyses reveal primary contributions of training interventions on mobility outcomes in patients >1-month poststroke. Age, duration poststroke, and baseline impairments were secondary predictors. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02507466 and NCT01789853.

Clinical Practice Guideline to Improve Locomotor Function Following Chronic Stroke, Incomplete Spinal Cord Injury, and Brain Injury.

BACKGROUND: Individuals with acute-onset central nervous system (CNS) injury, including stroke, motor incomplete spinal cord injury, or traumatic brain injury, often experience lasting locomotor deficits, as quantified by decreases in gait speed and distance walked over a specific duration (timed distance). The goal of the present clinical practice guideline was to delineate the relative efficacy of various interventions to improve walking speed and timed distance in ambulatory individuals greater than 6 months following these specific diagnoses. METHODS: A systematic review of the literature published between 1995 and 2016 was performed in 4 databases for randomized controlled clinical trials focused on these specific patient populations, at least 6 months postinjury and with specific outcomes of walking speed and timed distance. For all studies, specific parameters of training interventions including frequency, intensity, time, and type were detailed as possible. Recommendations were determined on the basis of the strength of the evidence and the potential harm, risks, or costs of providing a specific training paradigm, particularly when another intervention may be available and can provide greater benefit. RESULTS: Strong evidence indicates that clinicians should offer walking training at moderate to high intensities or virtual reality-based training to ambulatory individuals greater than 6 months following acute-onset CNS injury to improve walking speed or distance. In contrast, weak evidence suggests that strength training, circuit (ie, combined) training or cycling training at moderate to high intensities, and virtual reality-based balance training may improve walking speed and distance in these patient groups. Finally, strong evidence suggests that body weight-supported treadmill training, robotic-assisted training, or sitting/standing balance training without virtual reality should not be performed to improve walking speed or distance in ambulatory individuals greater than 6 months following acute-onset CNS injury to improve walking speed or distance. DISCUSSION: The collective findings suggest that large amounts of task-specific (ie, locomotor) practice may be critical for improvements in walking function, although only at higher cardiovascular intensities or with augmented feedback to increase patient's engagement. Lower-intensity walking interventions or impairment-based training strategies demonstrated equivocal or limited efficacy. LIMITATIONS: As walking speed and distance were primary outcomes, the research participants included in the studies walked without substantial physical assistance. This guideline may not apply to patients with limited ambulatory function, where provision of walking training may require substantial physical assistance. SUMMARY: The guideline suggests that task-specific walking training should be performed to improve walking speed and distance in those with acute-onset CNS injury although only at higher intensities or with augmented feedback. Future studies should clarify the potential utility of specific training parameters that lead to improved walking speed and distance in these populations in both chronic and subacute stages following injury. DISCLAIMER: These recommendations are intended as a guide for clinicians to optimize rehabilitation outcomes for persons with chronic stroke, incomplete spinal cord injury, and traumatic brain injury to improve walking speed and distance.

A Stem Cell-Based Screening Platform Identifies Compounds that Desensitize Motor Neurons to Endoplasmic Reticulum Stress.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease selectively targeting motor neurons in the brain and spinal cord. The reasons for differential motor neuron susceptibility remain elusive. We developed a stem cell-based motor neuron assay to study cell-autonomous mechanisms causing motor neuron degeneration, with implications for ALS. A small-molecule screen identified cyclopiazonic acid (CPA) as a stressor to which stem cell-derived motor neurons were more sensitive than interneurons. CPA induced endoplasmic reticulum stress and the unfolded protein response. Furthermore, CPA resulted in an accelerated degeneration of motor neurons expressing human superoxide dismutase 1 (hSOD1) carrying the ALS-causing G93A mutation, compared to motor neurons expressing wild-type hSOD1. A secondary screen identified compounds that alleviated CPA-mediated motor neuron degeneration: three kinase inhibitors and tauroursodeoxycholic acid (TUDCA), a bile acid derivative. The neuroprotective effects of these compounds were validated in human stem cell-derived motor neurons carrying a mutated SOD1 allele (hSOD1A4V). Moreover, we found that the administration of TUDCA in an hSOD1G93A mouse model of ALS reduced muscle denervation. Jointly, these results provide insights into the mechanisms contributing to the preferential susceptibility of ALS motor neurons, and they demonstrate the utility of stem cell-derived motor neurons for the discovery of new neuroprotective compounds.

Contributions of Stepping Intensity and Variability to Mobility in Individuals Poststroke.

Background and Purpose- The amount of task-specific stepping practice provided during rehabilitation poststroke can influence locomotor recovery and reflects one aspect of exercise dose that can affect the efficacy of specific interventions. Emerging data suggest that markedly increasing the intensity and variability of stepping practice may also be critical, although such strategies are discouraged during traditional rehabilitation. The goal of this study was to determine the individual and combined contributions of intensity and variability of stepping practice to improving walking speed and distance in individuals poststroke. Methods- This phase 2, randomized, blinded assessor clinical trial was performed between May 2015 and November 2018. Individuals between 18 and 85 years old with hemiparesis poststroke of >6 months duration were recruited. Of the 152 individuals screened, 97 were randomly assigned to 1 of 3 training groups, with 90 completing >10 sessions. Interventions consisted of either high-intensity stepping (70%-80% heart rate reserve) of variable, difficult stepping tasks (high variable), high-intensity stepping performing only forward walking (high forward), and low-intensity stepping in variable contexts at 30% to 40% heart rate reserve (low variable). Participants received up to 30 sessions over 2 months, with testing at baseline, post-training, and a 3-month follow-up. Primary outcomes included walking speeds and timed distance, with secondary measures of dynamic balance, transfers, spatiotemporal kinematics, and metabolic measures. Results- All walking gains were significantly greater following either high-intensity group versus low-variable training (all P<0.001) with significant correlations with stepping amount and rate (r=0.48-60; P<0.01). Additional gains in spatiotemporal symmetry were observed with high-intensity training, and balance confidence increased only following high-variable training in individuals with severe impairments. Conclusions- High-intensity stepping training resulted in greater improvements in walking ability and gait symmetry than low-intensity training in individuals with chronic stroke, with potential greater improvements in balance confidence. Clinical Trial Registration- URL: https://www.clinicaltrials.gov. Unique identifier: NCT02507466.

LINGO-1 Regulates Oligodendrocyte Differentiation through the Cytoplasmic Gelsolin Signaling Pathway.

Differentiation and maturation of oligodendrocyte progenitor cells (OPCs) involve the assembly and disassembly of actin microfilaments. However, how actin dynamics are regulated during this process remains poorly understood. Leucine-rich repeat and Ig-like domain-containing Nogo receptor interacting protein 1 (LINGO-1) is a negative regulator of OPC differentiation. We discovered that anti-LINGO-1 antibody-promoted OPC differentiation was accompanied by upregulation of cytoplasmic gelsolin (cGSN), an abundant actin-severing protein involved in the depolymerization of actin filaments. Treating rat OPCs with cGSN siRNA reduced OPC differentiation, whereas overexpression of cGSN promoted OPC differentiation in vitro and remyelination in vivo Furthermore, coexpression of cGSN and LINGO-1 blocked the inhibitory effect of LINGO-1. Our study demonstrates that cGSN works downstream of LINGO-1 signaling pathway, which enhances actin dynamics and is essential for OPC morphogenesis and differentiation. This finding may lead to novel therapeutic approaches for the treatment of demyelinating diseases such as multiple sclerosis (MS).SIGNIFICANCE STATEMENT Myelin loss and subsequent axon degeneration contributes to a variety of neurological diseases, such as multiple sclerosis (MS). Understanding the regulation of myelination by oligodendrocytes is therefore critical for developing therapies for the treatment of MS. We previously demonstrated that leucine-rich repeat and Ig-like domain-containing Nogo receptor interacting protein 1 (LINGO-1) is a negative regulator of oligodendrocyte differentiation and that anti-LINGO-1 promotes remyelination in preclinical animal models for MS and in a phase II acute optic neuritis clinical trial (RENEW). The mechanism by which LINGO-1 regulates oligodendrocyte differentiation is unknown. Here, we demonstrate that LINGO-1 regulates oligodendrocyte differentiation and maturation through the cytoplasmic gelsolin signaling pathway, providing new drug targets for the treatment of demyelination diseases.

Motor neuron diversity in development and disease.

Although often considered as a group, spinal motor neurons are highly diverse in terms of their morphology, connectivity, and functional properties and differ significantly in their response to disease. Recent studies of motor neuron diversity have clarified developmental mechanisms and provided novel insights into neurodegeneration in amyotrophic lateral sclerosis (ALS). Motor neurons of different classes and subtypes--fast/slow, alpha/gamma--are grouped together into motor pools, each of which innervates a single skeletal muscle. Distinct mechanisms regulate their development. For example, glial cell line-derived neurotrophic factor (GDNF) has effects that are pool-specific on motor neuron connectivity, column-specific on axonal growth, and subtype-specific on survival. In multiple degenerative contexts including ALS, spinal muscular atrophy (SMA), and aging, fast-fatigable (FF) motor units degenerate early, whereas motor neurons innervating slow muscles and those involved in eye movement and pelvic sphincter control are strikingly preserved. Extrinsic and intrinsic mechanisms that confer resistance represent promising therapeutic targets in these currently incurable diseases.

Intermediate filament protein accumulation in motor neurons derived from giant axonal neuropathy iPSCs rescued by restoration of gigaxonin.

Giant axonal neuropathy (GAN) is a progressive neurodegenerative disease caused by autosomal recessive mutations in the GAN gene resulting in a loss of a ubiquitously expressed protein, gigaxonin. Gene replacement therapy is a promising strategy for treatment of the disease; however, the effectiveness and safety of gigaxonin reintroduction have not been tested in human GAN nerve cells. Here we report the derivation of induced pluripotent stem cells (iPSCs) from three GAN patients with different GAN mutations. Motor neurons differentiated from GAN iPSCs exhibit accumulation of neurofilament (NF-L) and peripherin (PRPH) protein and formation of PRPH aggregates, the key pathological phenotypes observed in patients. Introduction of gigaxonin either using a lentiviral vector or as a stable transgene resulted in normalization of NEFL and PRPH levels in GAN neurons and disappearance of PRPH aggregates. Importantly, overexpression of gigaxonin had no adverse effect on survival of GAN neurons, supporting the feasibility of gene replacement therapy. Our findings demonstrate that GAN iPSCs provide a novel model for studying human GAN neuropathologies and for the development and testing of new therapies in relevant cell types.

Accelerated high-yield generation of limb-innervating motor neurons from human stem cells.

Human pluripotent stem cells are a promising source of differentiated cells for developmental studies, cell transplantation, disease modeling, and drug testing. However, their widespread use even for intensely studied cell types like spinal motor neurons is hindered by the long duration and low yields of existing protocols for in vitro differentiation and by the molecular heterogeneity of the populations generated. We report a combination of small molecules that within 3 weeks induce motor neurons at up to 50% abundance and with defined subtype identities of relevance to neurodegenerative disease. Despite their accelerated differentiation, motor neurons expressed combinations of HB9, ISL1, and column-specific markers that mirror those observed in vivo in human embryonic spinal cord. They also exhibited spontaneous and induced activity, and projected axons toward muscles when grafted into developing chick spinal cord. Strikingly, this novel protocol preferentially generates motor neurons expressing markers of limb-innervating lateral motor column motor neurons (FOXP1(+)/LHX3(-)). Access to high-yield cultures of human limb-innervating motor neuron subtypes will facilitate in-depth study of motor neuron subtype-specific properties, disease modeling, and development of large-scale cell-based screening assays.

Identification of a know-do gap: An observational study of the assessment and treatment of dysphagia during inpatient stroke rehabilitation in primary healthcare in Norway.

PURPOSE: Oropharyngeal dysphagia is a common swallowing impairment post-stroke managed by speech language pathologists (SLP). This article aims to demonstrate a local know-do gap assessment for usual dysphagia care for patients undergoing inpatient stroke rehabilitation in primary healthcare in Norway, which included an assessment of the functional level of the patients and characteristics and outcomes of treatment. MATERIALS AND METHODS: In this observational study, we assessed the outcomes and interventions of patients admitted to inpatient rehabilitation following stroke. The patients received usual care from SLPs while the research team administered a dysphagia assessment protocol that included assessment of several swallowing domains including oral intake, swallowing, patient self-reported functional health status and health-related quality of life, and oral health. The treating SLPs documented the treatments provided in a treatment diary. RESULTS: Of 91 patients who consented, 27 were referred for SLP and 14 received treatment. During the median treatment period of 31.5 days (IQR = 8.8-57.0), patients received 7.0 treatment sessions (IQR = 3.8-13.5) of 60 minutes (IQR = 55-60). The patients who received SLP treatment demonstrated no/minor disorders (n = 7) and moderate/severe disorders (n = 7). Dysphagia treatments primarily included oromotor training and advice on bolus modification and were provided without association to dysphagia severity. Patients with moderate/severe swallowing impairments received slightly more SLP sessions over a longer time. CONCLUSIONS: This study identified gaps between current and best practices and opportunities to improve assessment, decision-making, and implement evidence-based practices.

Comparative Efficacy of High-Intensity Training Versus Conventional Training in Individuals With Chronic Traumatic Brain Injury: A Pilot Randomized Controlled Study.

Numerous studies have evaluated the efficacy of interventions to improve locomotion after acute-onset brain injury, although most focus on patients with stroke, with less attention toward traumatic brain injury (TBI). For example, a number of studies in patients post-stroke have evaluated the effects of high-intensity training (HIT) attempting to maximize stepping practice, while no studies have attempted this intervention in patients with TBI. The purpose of this blinded-assessor randomized trial was to evaluate the effects of HIT focused on stepping practice versus conventional training on walking and secondary outcomes in individuals with TBI. Using a crossover design, ambulatory participants with TBI >6-months duration performed HIT focused on stepping in variable contexts (overground, treadmill, stairs) or conventional training for up to 15 sessions over five weeks, with interventions alternated >4 weeks later. HIT focused on maximizing stepping practice while trying to achieve higher cardiovascular intensities (>70% heart rate reserve), while conventional training focused on impairment-based and functional exercises with no restrictions on intensities achieved. Greater increases in 6-min walk test and peak treadmill speed during graded exercise testing were observed after HIT versus conventional training, with moderate associations between differences in stepping practice and outcomes. Greater gains were also observed in estimates of aerobic capacity and efficiency after HIT, with additional improvements in selected cognitive assessments. The present study suggests that the amount and intensity of stepping practice may be important determinants of improved locomotor outcomes in patients with chronic TBI, with possible secondary benefits on aerobic capacity/efficiency and cognition. Clinical Trial Registration-URL: https://clinicaltrials.gov/; Unique Identifier: NCT04503473.

Reduced calreticulin levels link endoplasmic reticulum stress and Fas-triggered cell death in motoneurons vulnerable to ALS.

Cellular responses to protein misfolding are thought to play key roles in triggering neurodegeneration. In the mutant superoxide dismutase (mSOD1) model of amyotrophic lateral sclerosis (ALS), subsets of motoneurons are selectively vulnerable to degeneration. Fast fatigable motoneurons selectively activate an endoplasmic reticulum (ER) stress response that drives their early degeneration while a subset of mSOD1 motoneurons show exacerbated sensitivity to activation of the motoneuron-specific Fas/NO pathway. However, the links between the two mechanisms and the molecular basis of their cellular specificity remained unclear. We show that Fas activation leads, specifically in mSOD1 motoneurons, to reductions in levels of calreticulin (CRT), a calcium-binding ER chaperone. Decreased expression of CRT is both necessary and sufficient to trigger SOD1(G93A) motoneuron death through the Fas/NO pathway. In SOD1(G93A) mice in vivo, reductions in CRT precede muscle denervation and are restricted to vulnerable motor pools. In vitro, both reduced CRT and Fas activation trigger an ER stress response that is restricted to, and required for death of, vulnerable SOD1(G93A) motoneurons. Our data reveal CRT as a critical link between a motoneuron-specific death pathway and the ER stress response and point to a role of CRT levels in modulating motoneuron vulnerability to ALS.

Increasing activity after stroke: a randomized controlled trial of highintensity walking and step activity intervention.

Background: Physical inactivity in people with chronic stroke profoundly affects daily function and increases recurrent stroke risk and mortality, making physical activity improvements an important target of intervention. We compared the effects of a highintensity walking intervention (FAST), a step activity monitoring behavioral intervention (SAM), or a combined intervention (FAST+SAM) on physical activity (i.e., steps per day). We hypothesized the combined intervention would yield the greatest increase in steps per day. Methods: This assessor-blinded multi-site randomized controlled trial was conducted at four university/hospital-based laboratories. Participants were 21-85 years old, walking without physical assistance following a single, unilateral non-cerebellar stroke of ≥6 months duration, and randomly assigned to FAST, SAM, or FAST+SAM for 12 weeks (2-3 sessions/week). FAST training consisted of walking-related activities for 40 minutes/session at 70-80% heart rate reserve, while SAM received daily feedback and goal-setting of walking activity (steps per day). Assessors and study statistician were masked to group assignment.The a priori-determined primary outcome and primary endpoint was change in steps per day from pre- to post-intervention. Adverse events (AEs) were tracked after randomization. All randomized participants were included in the intent-to-treat analysis.This study is registered at ClinicalTrials.gov, NCT02835313. Findings: Participants were enrolled from July 18, 2016-November 16, 2021. Of 250 randomized participants (mean[SE] age 63[0.80], 116F/134M), 89 were assigned to FAST, 81 to SAM, and 80 to FAST+SAM. Steps per day significantly increased in both the SAM (mean[SE] 1542[267], 95%CI:1014-2069, p<0.001) and FAST+SAM groups (1307[280], 752-1861, p<0.001), but not in the FAST group (406[238], 63-876, p=0.09). There were no deaths or serious study-related AEs and all other minor AEs were similar between groups. Interpretation: Only individuals with chronic stroke who completed a step activity monitoring behavioral intervention with skilled coaching and goal progression demonstrated improvements in physical activity (steps per day).

Lentiviral-mediated silencing of SOD1 through RNA interference retards disease onset and progression in a mouse model of ALS.

Mutations in Cu/Zn superoxide dismutase (encoded by SOD1), one of the causes of familial amyotrophic lateral sclerosis (ALS), lead to progressive death of motoneurons through a gain-of-function mechanism. RNA interference (RNAi) mediated by viral vectors allows for long-term reduction in gene expression and represents an attractive therapeutic approach for genetic diseases characterized by acquired toxic properties. We report that in SOD1(G93A) transgenic mice, a model for familial ALS, intraspinal injection of a lentiviral vector that produces RNAi-mediated silencing of SOD1 substantially retards both the onset and the progression rate of the disease.

Step Monitor Accuracy During PostStroke Physical Therapy and Simulated Activities.

Introduction/Purpose: The amount of stepping activity during rehabilitation post-stroke can predict walking outcomes, although the most accurate methods to evaluate stepping activity are uncertain with conflicting findings on available stepping monitors during walking assessments. Rehabilitation sessions also include non-stepping activities and the ability of activity monitors to differentiate these activities from stepping is unclear. The objective of this study was to examine the accuracy of different activity monitors worn by individuals post-stroke with variable walking speeds during clinical physical therapy (PT) and research interventions focused on walking. Methods: In Part I, 28 participants post-stroke wore a StepWatch, ActiGraph with and without a Low Frequency Extension (LFE) filter, and Fitbit on paretic and non-paretic distal shanks at or above the ankle during clinical PT or research interventions with steps simultaneously hand counted. Mean absolute percent errors were compared between limbs and tasks performed. In Part II, 12 healthy adults completed 8 walking and 9 non-walking tasks observed during clinical PT or research. Data were descriptively analyzed and used to assist interpretation of Part I results. Results: Part I results indicate most devices did not demonstrate an optimal limb configuration during research sessions focused on walking, with larger errors during clinical PT on the non-paretic limb. Using the limb that minimized errors for each device, the StepWatch had smaller errors than the ActiGraph and Fitbit (p<0.01), particularly in those who walked < 0.8 m/s. Conversely, errors from the ActiGraph-LFE demonstrated inconsistent differences in step counts between Fitbit and ActiGraph. Part II results indicate that errors observed during different stepping and non-stepping activities were often device-specific, with non-stepping tasks frequently detected as stepping. Conclusions: The StepWatch and ActiGraph-LFE had smaller errors than the Fitbit or ActiGraph, with greater errors in those walking at slower speeds. Inclusion of non-stepping activities affected step counts and should be considered when measuring stepping activity in individuals post-stroke to predict locomotor outcomes following rehabilitation.