Endothelial cell TRPA1 activity exacerbates cerebral hemorrhage during severe hypertension.

Introduction: Hypoxia-induced dilation of cerebral arteries orchestrated by Ca2+-permeable transient receptor potential ankyrin 1 (TRPA1) cation channels on endothelial cells is neuroprotective during ischemic stroke, but it is unknown if the channel has a similar impact during hemorrhagic stroke. TRPA1 channels are endogenously activated by lipid peroxide metabolites generated by reactive oxygen species (ROS). Uncontrolled hypertension, a primary risk factor for the development of hemorrhagic stroke, is associated with increased ROS production and oxidative stress. Therefore, we hypothesized that TRPA1 channel activity is increased during hemorrhagic stroke. Methods: Severe, chronic hypertension was induced in control (Trpa1 fl/fl) and endothelial cell-specific TRPA1 knockout (Trpa1-ecKO) mice using a combination of chronic angiotensin II administration, a high-salt diet, and the addition of a nitric oxide synthase inhibitor to drinking water. Blood pressure was measured in awake, freely-moving mice using surgically placed radiotelemetry transmitters. TRPA1-dependent cerebral artery dilation was evaluated with pressure myography, and expression of TRPA1 and NADPH oxidase (NOX) isoforms in arteries from both groups was determined using PCR and Western blotting techniques. In addition, ROS generation capacity was evaluated using a lucigenin assay. Histology was performed to examine intracerebral hemorrhage lesion size and location. Results: All animals became hypertensive, and a majority developed intracerebral hemorrhages or died of unknown causes. Baseline blood pressure and responses to the hypertensive stimulus did not differ between groups. Expression of TRPA1 in cerebral arteries from control mice was not altered after 28 days of treatment, but expression of three NOX isoforms and the capacity for ROS generation was increased in hypertensive animals. NOX-dependent activation of TRPA1 channels dilated cerebral arteries from hypertensive animals to a greater extent compared with controls. The number of intracerebral hemorrhage lesions in hypertensive animals did not differ between control and Trpa1-ecKO animals but were significantly smaller in Trpa1-ecKO mice. Morbidity and mortality did not differ between groups. Discussion: We conclude that endothelial cell TRPA1 channel activity increases cerebral blood flow during hypertension resulting in increased extravasation of blood during intracerebral hemorrhage events; however, this effect does not impact overall survival. Our data suggest that blocking TRPA1 channels may not be helpful for treating hypertension-associated hemorrhagic stroke in a clinical setting.

Spatio-temporal gait differences in facioscapulohumeral muscular dystrophy during single and dual task overground walking - A pilot study.

Background: Facioscapulohumeral muscular dystrophy (FSHD) is a rare genetic muscle disorder leading to progressive muscle loss over time. Research indicates that this progressive muscular atrophy can negatively impact spatio-temporal gait characteristics, but this is not always the case during early-onset or mild cases of the disease. In addition, the performance of a secondary task during overground walking may elucidate greater deficits in spatio-temporal characteristics of gait. However, such dual task effects on FSHD gait have not been studied thus far. Aim: The current study aimed to (a) quantify changes in spatio-temporal gait parameters in individuals with FSHD using the Tekscan Strideway gait mat system, (b) measure the dual task (DT) effects on cadence and gait velocity during single task (ST) and DT overground walking in FSHD and healthy controls and (c) investigate the correlation between the gait parameters and the methylation status in FSHD. Methods: Nine FSHD (M±SD=52.78±14.69 years) and nine nearly matched healthy controls (M±SD=50.11±16.18 years) performed five ST and five DT walking in a pseudo-randomized order. The DT included a serial 7's subtraction task from a random number between 50 and 100. Dependent variables: Cadence (steps/min) and gait velocity (cm/sec) were obtained from Tekscan Strideway (30 Hz, Boston, MA). Results: The pairwise comparison indicated that cadence was significantly different for both ST (P<0.004) and DT (P<0.02) where FSHD showed lower cadence compared to controls. Gait velocity was also significantly lower for FSHD during ST (P<0.004) and DT (P<0.008). Multilevel modeling (MLM) approach revealed a group by task interaction for cadence (P<0.05) and gait velocity (P<0.001). The interaction showed a significant difference between ST and DT in controls for cadence and gait velocity. However, there was no difference between ST and DT in FSHD. Finally, a comparison of methylation percentage versus gait parameters revealed a significant negative correlation coefficient for cadence but not for gait velocity. Conclusion: These results indicate specific pairwise differences in both ST and DT walking, observed in the gait parameters as decreased cadence and gait velocity during ST and DT. In addition, the MLM showed that controls exhibited the DT cost as expected but FSHD did not for cadence and gait velocity. Relevance for Patients: ST appears to be sufficiently challenging in FSHD and results in overall declines in spatio-temporal characteristics of gait. Further research is needed to test this paradigm with early-onset or mild cases to track disease progression and its effects on ambulation.

Sport-related concussion adopt a more conservative approach to straight path walking and turning during tandem gait.

BACKGROUND: It is currently unknown what specific neuronal deficits influence postural instability following SRC; however, the modulation of postural control relies heavily on the appropriate integration of sensory information from the visual, vestibular, and somatosensory system. It is possible symptom provocation of vestibular or ocular function is related to unsteady gait patterns during tandem gait. AIM: The purpose of this study was to evaluate the differences in temporal and center of pressure (CoP) metrics during discrete events of instrumented tandem gait (iTG) among those with sport-related concussion (SRC) compared to healthy controls. Secondarily, this study attempted to evaluate the relationship between iTG CoP metrics and the Vestibular/Ocular Motor Screening (VOMS) Exam. MATERIALS AND METHODS: 30 collegiate athletes with SRC and 30 healthy controls completed three single task (ST) iTG trials on an instrumented walkway and the VOMS. All individuals with SRC were assessed within 24-48 h post-injury while all controls were measured during pre-participation physicals. CoP metrics in the anteroposterior (AP) and mediolateral (ML) directions and time to completion were evaluated during the first, turn and second pass of iTG between groups. VOMS score was correlated to the CoP metrics across the discrete events. RESULTS: Athletes with SRC took longer to complete tandem gait (P<0.001) along with the first pass, second pass but not the turn when compared to the control group. SRC had slower velocity in the AP direction during both the first (P<0.001) and second pass (P<0.001) with increased postural sway in the ML direction during the first pass (P=0.014). During the turn, athletes with SRC had postural sway in the ML direction (P=0.008). Finally, VOMS score was weakly negatively related to CoP velocity in the AP direction during first (r=-0.39) and second (r=-0.36) pass while being weakly positively related to postural sway during the turn (r=-0.30). CONCLUSIONS: Athletes with SRC adopted a more conservative walking pattern and the presence of vestibular and/or ocular symptoms influence the ability to perform heel-to-toe walking. RELEVANCE FOR PATIENTS: Individuals with SRC will walk slower during heel-to-toe walking and move more in the ML direction with great movement in the ML direction while en pointe turning. This may increase given the total amount of vestibular or vision symptoms following the SRC.

Repetitive head impacts affect mediolateral postural sway entropy in the absence of vision following a competitive athletic season: preliminary findings.

BACKGROUND: Repetitive head impacts (RHIs) have received more notice over the past decade. More sensitive measures, such as postural control, have been used to evaluate if there are biomechanical changes after RHI exposure. Similar to the clinical findings, most of the studies have failed to find any significant changes across an athletic season. However, these studies included those with a concussion history and only assessed postural control in the eyes open (EO) condition, rather than in both the EO and eyes closed (EC) conditions. AIM: The purpose of this study was to investigate postural control changes during quiet stance following a season of RHI in Division I football athletes who did not have a prior diagnosed signet ring cell compared to a group of non-RHI athletes with no history of a diagnosed sport-related concussion. MATERIALS AND METHODS: Eighteen male Division I athletes were recruited and met the inclusion criteria: Nine football athletes (RHI group) and nine baseball athletes (CON group). All athletes performed three 30 s trials while standing with feet together on a force platform during EC and EO conditions. Center of pressure data was analyzed with sample entropy (SampEn) in the anteroposterior (AP) and mediolateral (ML) directions. SampEn data were analyzed with a three-level linear mixed effects model or the multilevel model, with the three levels being condition, time, and group. RESULTS: The analysis reported no significant effect for SampEn AP, but reported a significant three-way interaction (Group by Task by Time) for SampEn ML. Specifically, SampEn ML was significantly higher for EC than EO for both groups. CONCLUSIONS: There are postural control changes from pre- to post-season, with the main contributor being EC postural control. Thus, there could be a change in the sensory reweighting dynamics due to RHI and the effect of sport. RELEVANCE FOR PATIENTS: RHI may be better assessed in the clinical setting with EC, rather than with EO. Furthermore, clinicians should include tasks that deprive sensory inputs to examine the effects of RHI.

Water Immersion Affects Episodic Memory and Postural Control in Healthy Older Adults.

BACKGROUND AND PURPOSE: Previous research has reported that younger adults make fewer cognitive errors on an auditory vigilance task while in chest-deep water compared with on land. The purpose of this study was to extend this previous work to include older adults and to examine the effect of environment (water vs land) on linear and nonlinear measures of postural control under single- and dual-task conditions. METHODS: Twenty-one older adult participants (age = 71.6 ± 8.34 years) performed a cognitive (auditory vigilance) and motor (standing balance) task separately and simultaneously on land and in chest-deep water. Listening errors (n = count) from the auditory vigilance test and sample entropy (SampEn), center of pressure area, and velocity for the balance test served as dependent measures. Environment (land vs water) and task (single vs dual) comparisons were made with a Wilcoxon matched-pair test. RESULTS: Listening errors were 111% greater during land than during water environments (single-task = 4.0 ± 3.5 vs 1.9 ± 1.7; P = .03). Conversely, SampEn values were 100% greater during water than during land environments (single-task = 0.04 ± 0.01 vs 0.02 ± 0.01; P < .001). Center of pressure area and velocity followed a similar trend to SampEn with respect to environment differences, and none of the measures were different between single- and dual-task conditions (P > .05). CONCLUSIONS: The findings of this study expand current support for the potential use of partial aquatic immersion as a viable method for challenging both cognitive and motor abilities in older adults.

Interaction of Perception and Action in Discrete and Continuous Rapid Aiming Tasks.

Previously, we have shown that discrete and continuous rapid aiming tasks are governed by distinct visuomotor control mechanisms by assessing the combined visual illusion effects on the perceived and effective index of difficulty (ID). All participants were perceptually biased by the combined visual illusion before they performed the rapid aiming tasks. In the current study, the authors manipulated the order of performing perceptual and motor tasks to examine whether perceptual or motor experience with the illusory visual target would influence the subsequent perceived and effective ID in discrete and continuous tapping tasks. The results supported our hypothesis showing that perceptual experience with the illusory visual target in the discrete condition reduced the effective ID in the subsequent discrete tapping task, and motor experience with the illusory visual target in the continuous condition reduced the illusion effects on the perceived ID in the subsequent perceptual judgment task. The study demonstrates the coinfluence of perception and action, and suggests that perception and action influence one another with different magnitude depending on the spatial frame of reference used to perform the perceptuomotor task.

Combined visual illusion effects on the perceived index of difficulty and movement outcomes in discrete and continuous fitts' tapping.

The speed-accuracy trade-off is a fundamental movement problem that has been extensively investigated. It has been established that the speed at which one can move to tap targets depends on how large the targets are and how far they are apart. These spatial properties of the targets can be quantified by the index of difficulty (ID). Two visual illusions are known to affect the perception of target size and movement amplitude: the Ebbinghaus illusion and Muller-Lyer illusion. We created visual images that combined these two visual illusions to manipulate the perceived ID, and then examined people's visual perception of the targets in illusory context as well as their performance in tapping those targets in both discrete and continuous manners. The findings revealed that the combined visual illusions affected the perceived ID similarly in both discrete and continuous judgment conditions. However, the movement outcomes were affected by the combined visual illusions according to the tapping mode. In discrete tapping, the combined visual illusions affected both movement accuracy and movement amplitude such that the effective ID resembled the perceived ID. In continuous tapping, none of the movement outcomes were affected by the combined visual illusions. Participants tapped the targets with higher speed and accuracy in all visual conditions. Based on these findings, we concluded that distinct visual-motor control mechanisms were responsible for execution of discrete and continuous Fitts' tapping. Although discrete tapping relies on allocentric information (object-centered) to plan for action, continuous tapping relies on egocentric information (self-centered) to control for action. The planning-control model for rapid aiming movements is supported.