Κυριακή 28 Αυγούστου 2016

Temporal and spatial gait parameters in children with Cri du Chat Syndrome under single and dual task conditions

Publication date: October 2016
Source:Gait & Posture, Volume 50
Author(s): Laurel D. Abbruzzese, Rachel Salazar, Maddie Aubuchon, Ashwini K. Rao
AimTo describe temporal and spatial gait characteristics in individuals with Cri du Chat syndrome (CdCS) and to explore the effects of performing concurrent manual tasks while walking.MethodsThe gait parameters of 14 participants with CdCS (mean age 10.3, range 3–20 years) and 14 age-matched controls (mean age 10.1, range 3–20 years) were collected using the GAITRite® instrumented walkway. All participants first walked without any concurrent tasks and then performed 2 motor dual task walking conditions (pitcher and tray).ResultsIndividuals with CdCS took more frequent, smaller steps than controls, but, on average, had a comparable gait speed. In addition, there was a significant task by group interaction. Participants decreased gait speed, decreased cadence, decreased step length, and increased% time in double limb support under dual task conditions compared to single task conditions. However, the age-matched controls altered their gait for both manual tasks, and the participants with CdCS only altered their gait for the tray task.InterpretationAlthough individuals with CdCS ambulate with a comparable gait speed to age-matched controls under single task conditions, they did not significantly alter their gait when carrying a pitcher with a cup of water inside, like controls. It is not clear whether or not individuals with CdCS had difficulty attending to task demands or had difficulty modifying their gait.



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Reduced knee adduction moments for management of knee osteoarthritis:

Publication date: October 2016
Source:Gait & Posture, Volume 50
Author(s): Ryan T. Lewinson, Isabelle A. Vallerand, Kelsey H. Collins, J. Preston Wiley, Victor M.Y. Lun, Chirag Patel, Linda J. Woodhouse, Raylene A. Reimer, Jay T. Worobets, Walter Herzog, Darren J. Stefanyshyn
Wedged insoles are believed to be of clinical benefit to individuals with knee osteoarthritis by reducing the knee adduction moment (KAM) during gait. However, previous clinical trials have not specifically controlled for KAM reduction at baseline, thus it is unknown if reduced KAMs actually confer a clinical benefit. Forty-eight participants with medial knee osteoarthritis were randomly assigned to either a control group where no footwear intervention was given, or a wedged insole group where KAM reduction was confirmed at baseline. KAMs, Knee Injury and Osteoarthritis Outcome Score (KOOS) and Physical Activity Scale for the Elderly (PASE) scores were measured at baseline. KOOS and PASE surveys were re-administered at three months follow-up. The wedged insole group did not experience a statistically significant or clinically meaningful change in KOOS pain over three months (p=0.173). Furthermore, there was no association between change in KAM magnitude and change in KOOS pain over three months within the wedged insole group (R2=0.02, p=0.595). Improvement in KOOS pain for the wedged insole group was associated with worse baseline pain, and a change in PASE score over the three month study (R2=0.57, p=0.007). As an exploratory comparison, there was no significant difference in change in KOOS pain (p=0.49) between the insole and control group over three months. These results suggest that reduced KAMs do not appear to provide any clinical benefit compared to no intervention over a follow-up period of three months. ClinicalTrials.gov ID Number: NCT02067208



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Decreased high-frequency center-of-pressure complexity in recently concussed asymptomatic athletes

Publication date: October 2016
Source:Gait & Posture, Volume 50
Author(s): Peter C. Fino, Maury A. Nussbaum, Per Gunnar Brolinson
Two experiments compared multiple methods of estimating postural stability entropy to address: 1) if postural complexity differences exist between concussed and healthy athletes immediately following return-to-play; 2) which methods best detect such differences; and 3) what is an appropriate interpretation of such differences. First, center of pressure (COP) data were collected from six concussed athletes over the six weeks immediately following their concussion and from 24 healthy athletes. Second, 25 healthy non-athletes performed four quiet standing tasks: normal, co-contracting their lower extremity muscles, performing a cognitive arithmetic task, and voluntarily manipulating their sway. Postural complexity was calculated using approximate, sample, multi-variate sample, and multi-variate composite multi-scale (MV-CompMSE) entropy methods for both high-pass filtered and low-pass filtered COP data. MV-CompMSE of the high-pass filtered COP signal identified the most consistent differences between groups, with concussed athletes exhibiting less complexity over the high frequency COP time-series. Among healthy non-athletes, high-pass filtered MV-CompMSE increased only in the co-contraction condition, suggesting the decrease in high frequency MV-CompMSE found in concussed athletes may be due to more relaxed muscles or less complex muscle contractions. This decrease in entropy may associate with reported increases in intra-cortical inhibition. Furthermore, a single-case study suggested high frequency MV-CompMSE may be a useful clinical tool for concussion management.



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Toddlers actively reorganize their whole body coordination to maintain walking stability while carrying an object

Publication date: October 2016
Source:Gait & Posture, Volume 50
Author(s): Wen-Hao Hsu, Daniel L. Miranda, Trevor L. Chistolini, Eugene C. Goldfield
Balanced walking involves freely swinging the limbs like pendula. However, children immediately begin to carry objects as soon as they can walk. One possibility for this early skill development is that whole body coordination during walking may be re-organized into loosely coupled collections of body parts, allowing children to use their arms to perform one function, while the legs perform another. Therefore, this study examines: 1) how carrying an object affects the coordination of the arms and legs during walking, and 2) if carrying an object influences stride length and width. Ten healthy toddlers with 3–12 months of walking experience were recruited to walk barefoot while carrying or not carrying a small toy. Stride length, width, speed, and continuous relative phase (CRP) of the hips and of the shoulders were compared between carrying conditions. While both arms and legs demonstrated destabilization and stabilization throughout the gait cycle, the arms showed a reduction in intra-subject coordination variability in response to carrying an object. Carrying an object may modify the function of the arms from swinging for balance to maintaining hold of an object. The observed period-dependent changes of the inter-limb coordination of the hips and of the shoulders also support this interpretation. Overall, these findings support the view that whole-body coordination patterns may become partitioned in particular ways as a function of task requirements.



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Stereocilia morphogenesis and maintenance through regulation of actin stability.

Stereocilia morphogenesis and maintenance through regulation of actin stability.

Semin Cell Dev Biol. 2016 Aug 23;

Authors: McGrath J, Roy P, Perrin BJ

Abstract
Stereocilia are actin-based protrusions on auditory and vestibular sensory cells that are required for hearing and balance. They convert physical force from sound, head movement or gravity into an electrical signal, a process that is called mechanoelectrical transduction. This function depends on the ability of sensory cells to grow stereocilia of defined lengths. These protrusions form a bundle with a highly precise geometry that is required to detect nanoscale movements encountered in the inner ear. Congenital or progressive stereocilia degeneration causes hearing loss. Thus, understanding stereocilia hair bundle structure, development, and maintenance is pivotal to understanding the pathogenesis of deafness. Stereocilia cores are made from a tightly packed array of parallel, crosslinked actin filaments, the length and stability of which are regulated in part by myosin motors, actin crosslinkers and capping proteins. This review aims to describe stereocilia actin regulation in the context of an emerging "tip turnover" model where actin assembles and disassembles at stereocilia tips while the remainder of the core is exceptionally stable.

PMID: 27565685 [PubMed - as supplied by publisher]



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