Altered foot placement modulation with somatosensory stimulation in people with chronic stroke.

Many individuals who experience a stroke exhibit reduced modulation of their mediolateral foot placement, an important gait stabilization strategy. One factor that may contribute to this deficit is altered somatosensory processing, which can be probed by applying vibration to the involved muscles (e.g., the hip abductors). The purpose of this study was to investigate whether appropriately controlled hip abductor vibration can increase foot placement modulation among people with chronic stroke. 40 people with chronic stroke performed a series of treadmill walking trials without vibration and with vibration of either the hip abductors or lateral trunk (a control condition) that scaled with their real-time mediolateral motion. To assess participants' vibration sensitivity, we also measured vibration detection threshold and lateral sway evoked by abductor vibration during quiet standing. As a group, foot placement modulation increased significantly with either hip or trunk vibration, compared to without vibration. However, these changes were quite variable across participants, and were not predicted by either vibration detection threshold or the lateral sway evoked by hip vibration during standing. Overall, we found that somatosensory stimulation had small, positive effects on post-stroke foot placement modulation. Unexpectedly, these effects were observed with both hip abductor and lateral trunk vibration, perhaps indicating that the trunk can also provide useful somatosensory feedback during walking. Future work is needed to determine whether repeated application of such somatosensory stimulation can produce sustained effects on this important gait stabilization strategy.

Relationships between mediolateral step modulation and clinical balance measures in people with chronic stroke.

BACKGROUND: Many people with chronic stroke (PwCS) exhibit walking balance deficits linked to increased fall risk and decreased balance confidence. One potential contributor to these balance deficits is a decreased ability to modulate mediolateral stepping behavior based on pelvis motion. This behavior, hereby termed mediolateral step modulation, is thought to be an important balance strategy but can be disrupted in PwCS. RESEARCH QUESTION: Are biomechanical metrics of mediolateral step modulation related to common clinical balance measures among PwCS? METHODS: In this cross-sectional study, 93 PwCS walked on a treadmill at their self-selected speed for 3-minutes. We quantified mediolateral step modulation for both paretic and non-paretic steps by calculating partial correlations between mediolateral pelvis displacement at the start of each step and step width (ρSW), mediolateral foot placement relative to the pelvis (ρFP), and final mediolateral location of the pelvis (ρPD) at the end of the step. We also assessed several common clinical balance measures (Functional Gait Assessment [FGA], Activities-specific Balance Confidence scale [ABC], self-reported fear of falling and fall history). We performed Spearman correlations to relate each biomechanical metric of step modulation to FGA and ABC scores. We performed Wilcoxon rank sum tests to compare each biomechanical metric between individuals with and without a fear of falling and a history of falls. RESULTS: Only ρFP for paretic steps was significantly related to all four clinical balance measures; higher paretic ρFP values tended to be observed in participants with higher FGA scores, with higher ABC scores, without a fear of falling and without a history of falls. However, the strength of each of these relationships was only weak to moderate. SIGNIFICANCE: While the present results do not provide insight into causality, they justify future work investigating whether interventions designed to increase ρFP can improve clinical measures of post-stroke balance in parallel.

Effect of novel training to normalize altered finger force direction post-stroke: study protocol for a double-blind randomized controlled trial.

BACKGROUND: Functional task performance requires proper control of both movement and force generation in three-dimensional space, especially for the hand. Control of force in three dimensions, however, is not explicitly treated in current physical rehabilitation. To address this gap in treatment, we have developed a tool to provide visual feedback on three-dimensional finger force. Our objective is to examine the effectiveness of training with this tool to restore hand function in stroke survivors. METHODS: Double-blind randomized controlled trial. All participants undergo 18 1-h training sessions to practice generating volitional finger force of various target directions and magnitudes. The experimental group receives feedback on both force direction and magnitude, while the control group receives feedback on force magnitude only. The primary outcome is hand function as measured by the Action Research Arm Test. Other outcomes include the Box and Block Test, Stroke Impact Scale, ability to direct finger force, muscle activation pattern, and qualitative interviews. DISCUSSION: The protocol for this clinical trial is described in detail. The results of this study will reveal whether explicit training of finger force direction in stroke survivors leads to improved motor control of the hand. This study will also improve the understanding of neuromuscular mechanisms underlying the recovery of hand function. TRIAL REGISTRATION: ClinicalTrials.gov NCT03995069 . Registered on June 21, 2019.

Concomitant sensory stimulation during therapy to enhance hand functional recovery post stroke.

BACKGROUND: Post-stroke hand impairment is prevalent and persistent even after a full course of rehabilitation. Hand diminishes stroke survivors' abilities for activities of daily living and independence. One way to improve treatment efficacy is to augment therapy with peripheral sensory stimulation. Recently, a novel sensory stimulation, TheraBracelet, has been developed in which imperceptible vibration is applied during task practice through a wrist-worn device. The objective of this trial is to determine if combining TheraBracelet with hand task practice is superior to hand task practice alone. METHODS: A double-blind randomized controlled trial will be used. Chronic stroke survivors will undergo a standardized hand task practice therapy program (3 days/week for 6 weeks) while wearing a device on the paretic wrist. The device will deliver TheraBracelet vibration for the treatment group and no vibration for the control group. The primary outcome is hand function measured by the Wolf Motor Function Test. Other outcomes include the Box and Block Test, Action Research Arm Test, upper extremity use in daily living, biomechanical measure of the sensorimotor grip control, and EEG-based neural communication. DISCUSSION: This research will determine clinical utility of TheraBracelet to guide future translation. The TheraBracelet stimulation is delivered via a wrist-worn device, does not interfere with hand motion, and can be easily integrated into clinical practice. Enhancing hand function should substantially increase stroke survivors' independence and quality of life and reduce caregiver burden. TRIAL REGISTRATION: NCT04569123 . Registered on September 29, 2020.

Cryptic evolved melts beneath monotonous basaltic shield volcanoes in the Galápagos Archipelago.

Many volcanoes erupt compositionally homogeneous magmas over timescales ranging from decades to millennia. This monotonous activity is thought to reflect a high degree of chemical homogeneity in their magmatic systems, leading to predictable eruptive behaviour. We combine petrological analyses of erupted crystals with new thermodynamic models to characterise the diversity of melts in magmatic systems beneath monotonous shield volcanoes in the Galápagos Archipelago (Wolf and Fernandina). In contrast with the uniform basaltic magmas erupted at the surface over long timescales, we find that the sub-volcanic systems contain extreme heterogeneity, with melts extending to rhyolitic compositions. Evolved melts are in low abundance and large volumes of basalt flushing through the crust from depth overprint their chemical signatures. This process will only maintain monotonous activity while the volume of melt entering the crust is high, raising the possibility of transitions to more silicic activity given a decrease in the crustal melt flux.

Examining Academic Support After Concussion for the Adolescent Student-Athlete: Perspectives of the Athletic Trainer.

CONTEXT: Student-athletes may require cognitive rest and academic support after concussion. Athletic trainers (ATs) in secondary schools are uniquely positioned to provide medical care and to collaborate with school professionals while managing concussions. However, little is known regarding return-to-learn policies and their implementation in secondary schools. OBJECTIVE: To examine ATs' perspectives on return to learn, cognitive rest, and communication with school professionals after concussion. DESIGN: Cross-sectional study. SETTING: Web-based survey. PATIENTS OR OTHER PARTICIPANTS: A total of 1124 secondary school ATs completed the survey (28.5% response rate). The majority of participants were employed full time (752/1114 [67.5%]) in public schools (911/1117 [81.6%]). MAIN OUTCOME MEASURE(S): School and AT employment characteristics, demographics, number of concussions evaluated annually, and perceptions of school professionals' familiarity with ATs' responsibilities were independent variables. RESULTS: Of the ATs, 44% reported having an existing return-to-learn policy. The strongest predictor of a return-to-learn policy was frequent communication with teachers after concussion (odds ratio = 1.5; 95% confidence interval = 1.2, 1.7). Most ATs recommended complete cognitive rest (eg, no reading, television; 492/1087 [45.3%]) or limited cognitive activity based upon symptoms (391/1087 [36.0%]). Common academic accommodations were postponed due dates (789/954 [82.7%]), rest breaks (765/954 [80.2%]), and partial attendance (740/954 [77.6%]). Athletic trainers self-reported as primary monitors of health (764/1037 [73.7%]) and academic progression (359/1011 [35.5%]). The strongest predictor of ATs' communication with school professionals was their perception of school professionals' understanding of ATs' roles. CONCLUSIONS: Overall, ATs followed best practices for cognitive rest and return to learn after concussion. Although ATs are central to the management of student-athletes' physical health after concussion, school professionals may be better suited to monitor academic progress. Increased communication between the AT and school professionals is recommended to monitor recovery and facilitate academic support for symptomatic student-athletes.

The A, B, C, D of hypercalcaemia in Down syndrome.

Hypercalcaemia in infants with Down syndrome is an uncommon condition with only five previous case reports. The patients often present in the toddler years with the classical triad of Down syndrome, biochemical hypercalcaemia, and nephrocalcinosis. We present the sixth case and second male with this condition and further review the clinical details of this under-recognised condition and stratify the diagnostic criteria. The management mandates a reduction in calcium intake as a first step. The natural history of the various aspects of this condition is also considered.

Riparian vegetation dynamics and evapotranspiration in the riparian corridor in the delta of the Colorado River, Mexico.

Like other great desert rivers, the Colorado River in the United States and Mexico is highly regulated to provide water for human use. No water is officially allotted to support the natural ecosystems in the delta of the river in Mexico. However, precipitation is inherently variable in this watershed, and from 1981-2004, 15% of the mean annual flow of the Lower Colorado River has entered the riparian corridor below the last diversion point for water in Mexico. These flows include flood releases from US dams and much smaller administrative spills released back to the river from irrigators in the US and Mexico. These flows have germinated new cohorts of native cottonwood and willow trees and have established an active aquatic ecosystem in the riparian corridor in Mexico. We used ground and remote-sensing methods to determine the composition and fractional cover of the vegetation in the riparian corridor, its annual water consumption, and the sources of water that support the ecosystem. The study covered the period 2000-2004, a flood year followed by 4 dry years. The riparian corridor occupies 30,000 ha between flood control levees in Mexico. Annual evapotranspiration (ET), estimated by Moderate Resolution Imaging Spectrometer (MODIS) satellite imagery calibrated against moisture flux tower data, was about 1.1 m yr(-1) and was fairly constant throughout the study period despite a paucity of surface flows 2001-2004. Total ET averaged 3.4 x 10(8)m(3)yr(-1), about 15% of Colorado River water entering Mexico from the US Surface flows could have played only a small part in supporting these high ET losses. We conclude that the riparian ET is supported mainly by the shallow regional aquifer, derived from agricultural return flows, that approaches the surface in the riparian zone. Nevertheless, surface flows are important in germinating cohorts of native trees, in washing salts from the soil and aquifer, and in providing aquatic habitat, thereby enriching the habitat value of the riparian corridor for birds and other wildlife. Conservation and water management strategies to enhance the delta habitats are discussed in light of the findings.

Expression of ICP0 is sufficient to trigger natural killer cell recognition of herpes simplex virus-infected cells by natural cytotoxicity receptors.

Natural killer (NK) cells are an important component of the immune response to a number of viruses; however, the molecular basis of how NK cells discriminate between healthy and virus-infected cells is largely unknown. Here, we show that expression of the immediate-early gene product ICP0 is sufficient to produce an increased susceptibility to NK lysis of herpes simplex virus (HSV)-infected cells. This effect does not depend on down-regulation of major histocompatibility complex class I molecules or on the induction of expression of ligands for the activating NKG2D receptor. Detection by NK cells of the changes in the target cell induced by HSV ICP0 gene expression depends on the natural cytotoxicity receptors (NCRs) NKp30, NKp44, and NKp46. To our knowledge, this is the first identification of a viral gene that triggers the up-regulation of cellular ligands for the NCR; moreover, these observations highlight the importance of the NCR for immunosurveillance of viral infection by NK cells.

HSV vector-delivery of GDNF in a rat model of PD: partial efficacy obscured by vector toxicity.

Herpes simplex virus (HSV)-derived vectors have been suggested for potential use in gene therapy for Parkinson's disease (PD). HSV naturally infects adult neuronal cells and possesses a large genome for the insertion of transgenes. In the present study, we have used two different HSV constructs to deliver glial cell line-derived neurotrophic factor (GDNF) to the striatum, and to assess the neuroprotective effects of the GDNF product in an intrastriatal 6-hydroxydopamine lesion model. One construct is blocked for IE gene expression whereas the other is deleted in the thymidine kinase gene. Both constructs induced a significant protection of the dopaminergic neurons in the substantia nigra from the lesions, whereas only one induced a transient behavioural recovery in amphetamine-induced rotation. Unexpectedly, the more deleted virus caused the greater toxicity. This was found to be due to the way the vector was purified. The issue of toxicity, which might account for the variable functional effects, needs resolving prior to therapeutic application of these vectors.