Collision avoidance strategies between two athlete walkers: Understanding impaired avoidance behaviours in athletes with a previous concussion.

BACKGROUND: Individuals who have sustained a concussion often display associated balance control deficits and visuomotor impairments despite being cleared by a physician to return to sport. Such visuomotor impairments can be highlighted in collision avoidance tasks that involves a mutual adaptation between two walkers. However, studies have yet to challenged athletes with a previous concussion during an everyday collision avoidance task, following return to sport. RESEARCH QUESTION: Do athletes with a previous concussion display associated behavioural changes during a 90°-collision avoidance task with an approaching pedestrian? METHODS: Thirteen athletes (ATH; 9 females, 23 ±â€¯4years) and 13 athletes with a previous concussion (CONC; 9 females, 22 ±â€¯3 years, concussion <6 months) walked at a comfortable walking speed along a 12.6 m pathway while avoiding another athlete on a 90º-collision course. Each participant randomly interacted with individuals from the same group 20 times and interacted with individuals from the opposite group 21 times. Minimum predicted distance (mpd) was used to examine collision avoidance behaviours between ATH and CONC groups. RESULTS: The overall progression of mpd(t) did not differ between groups (p > .05). During the collision avoidance task, previously concussed athletes contributed less when passing second compared to their peers(p < .001). When two previously concussed athletes were on a collision course, there was a greater amount of variability resulting in inappropriate adaptive behaviours. SIGNIFICANCE: Although successful at avoiding a collision with an approaching athlete, previously concussed athletes exhibit behavioural changes manifesting in riskier behaviours. The current findings suggest that previously concussed athletes possess behavioural changes even after being cleared to returned to sport, which may increase their risk of a subsequent injury when playing.

Collision avoidance behaviours between older adult and young adult walkers.

BACKGROUND: Collision avoidance between two walkers requires a mutual adaptation based on visual information in order to be successful. Age-related changes to visuomotor processing, kinesthetic input, and intersegmental dynamics increases the risk of collision and falls in older adults. However, few studies examine behavioural strategies in older adults during collision avoidance tasks with another pedestrian. RESEARCH QUESTION: Is there a difference between older adults' and young adults' collision avoidance behaviours with another pedestrian? METHODS: Seventeen older adults (x¯ = 68 ± 3 years) and seventeen young adults (x¯ = 23 ± 2 years) walked at a comfortable walking speed along a 12.6 m pathway while avoiding another walker. Trials were randomized equally to include 20 interactions with the same age group and 21 interactions with the opposite age group. Minimum predicted distance (mpd) was used to characterize collision avoidance behaviours between older adults and young adults. RESULTS: Older adults had riskier avoidance behaviours, passing closer to the other pedestrian (0.79 m ± 0.18 m) compared to when two young adults were on a collision course (0.93 m ± 0.17 m) (χ²(3) = 35.94, p < .0001). Whenever an older adult was on a collision course with a young adult, the young adult contributed more to the avoidance regardless of passing order. SIGNIFICANCE: The results from the current study highlight age-related effects during a collision avoidance task in older adults resulting in risky behaviour and a potential collision. Future studies should further investigate age-related visuomotor deficits during collision avoidance tasks in cluttered environments using virtual reality in order to tease out factors that contribute most to avoidance behaviours in older adults.

A predictive score of inadequate bowel preparation based on a self-administered questionnaire: PREPA-CO.

INTRODUCTION: Inadequate bowel preparation before colonoscopy has a 20-30% rate and impedes on the quality of the procedure. The aim of this study was to develop a predictive score of inadequate bowel preparation, using a patient questionnaire on potential risk factors. METHODS: In this single center study, consecutive patients with colonoscopy indication were enrolled. The primary outcome was inadequate bowel preparation defined by Boston Bowel Preparation Scale (BBPS) score <7 or a score ≤1 in any of the 3 colonic segments. RESULTS: A total of 561 patients were included. Inadequate bowel preparation was seen in 25.0% of cases. Seven risk factors were selected into the prediction model of inadequate bowel preparation: diabetes or obesity, irregular physical activity, cirrhosis, use of antidepressants or neuroleptics, use of opiate medication, history of surgery and history of inadequate bowel preparation. The risk score, named PREPA-CO, had an AUROC of 0.621, adequately predicted bowel cleanliness in 68.3% of cases, with a specificity of 75.8% and a negative predictive value of 80.8%. CONCLUSION: We developed a predictive score named "Prepa-Co", allowing the identification of patients at high risk of inadequate bowel preparation. In clinical practice, this score could help tailor the prescription of the preparation to the patient.

ABHD11, a new diacylglycerol lipase involved in weight gain regulation.

Obesity epidemic continues to spread and obesity rates are increasing in the world. In addition to public health effort to reduce obesity, there is a need to better understand the underlying biology to enable more effective treatment and the discovery of new pharmacological agents. Abhydrolase domain-containing protein 11 (ABHD11) is a serine hydrolase enzyme, localized in mitochondria, that can synthesize the endocannabinoid 2-arachidonoyl glycerol (2AG) in vitro. In vivo preclinical studies demonstrated that knock-out ABHD11 mice have a similar 2AG level as WT mice and exhibit a lean metabolic phenotype. Such mice resist to weight gain in Diet Induced Obesity studies (DIO) and display normal biochemical plasma parameters. Metabolic and transcriptomic analyses on serum and tissues of ABHD11 KO mice from DIO studies show a modulation in bile salts associated with reduced fat intestinal absorption. These data suggest that modulating ABHD11 signaling pathway could be of therapeutic value for the treatment of metabolic disorders.

Minimum predicted distance: Applying a common metric to collision avoidance strategies between children and adult walkers.

BACKGROUND: Collision avoidance between two walkers involves a mutual adaptation to speed and orientation in order to successfully avoid a collision. Minimum Predicted Distance (MPD) is the distance at which two walkers would collide if their speed and path trajectory were maintained at first sight of one another. MPD has been used to describe the risk of collision and its evolution over time between two adult walkers when on a collision course. Middle-aged children have been shown to have poor perception-action coupling during static and dynamic collision avoidance tasks. Research has yet to examine whether perception-action coupling deficits persist in a dynamic collision avoidance task involving a child and another walker. RESEARCH QUESTION: Can the metric MPD(t) be used to examine collision avoidance strategies between children and adults? METHODS: Eighteen children (age: 10 ±â€¯1.5 years) and eighteen adults (34 ±â€¯9.6 years) walked along a 12.6 m pathway while avoiding another participant (child or adult). Groups of three children and three adults were recruited per session. Trials were randomized equally such that each adult interacted with another adult 20 times, each child interacted with another child 20 times, and each adult interacted with a child 21 times, for a total of 141 trials. 3D kinematic data of each participant's head was recorded using the Vicon system. RESULTS: The results demonstrated: (1) MPD(t) can be used to predict future collisions in children, (2) MPD(t) is an absolute measure that is consistently lower when a child is involved compared to two adult walkers, (3) the individual passing second, even when it is a child, contributes more to MPD(t) than the walker passing first. SIGNIFICANCE: It appears children have developed adult-like strategies during a collision avoidance task involving two walkers. Body anthropometrics should be considered when determining collision avoidance strategies between children and adults.

Large oesophageal varice screening by a sequential algorithm using a cirrhosis blood test and optionally capsule endoscopy.

BACKGROUND & AIMS: Large oesophageal varice (LEV) screening is recommended in cirrhosis. We performed a prospective study to improve non-invasive LEV screening. DESIGN: 287 patients with cirrhosis had upper gastrointestinal endoscopy (LEV reference), oesophageal capsule endoscopy (ECE), liver elastography and blood marker analyses. CirrhoMeter (cirrhosis blood test), the most accurate non-invasive LEV test, was segmented for cirrhosis (reference comparator) or LEV. VariScreen, a sequential and partially minimally invasive diagnostic algorithm, was developed by multivariate analysis. It uses CirrhoMeter first, then ECE if CirrhoMeter cannot rule LEV out or in, and finally endoscopy if CirrhoMeter+ECE combination remains uninformative. RESULTS: Diagnostic effectiveness rates for LEV were: cirrhosis-segmented CirrhoMeter: 14.6%, LEV-segmented CirrhoMeter: 34.6%, ECE: 60.6% and VariScreen: 66.4% (P ≤ .001 for overall or pair comparison). The respective missed LEV rates were: 2.8%, 5.6%, 8.3% and 5.6% (P = .789). Spared endoscopy rates were, respectively: 15.6%, 36.0%, 70.6% and 69%, (P < .001 for overall or paired comparison except ECE vs VariScreen: P = .743). VariScreen spared 38% of ECE and reduced missed LEV by 87% compared to classical ECE performed in all patients. Excepting cirrhosis-segmented CirrhoMeter, these spared endoscopy rates were significantly higher than that of the Baveno VI recommendation (using platelets and Fibroscan): 18.4% (P < .001). Ascites and Child-Pugh class independently predicted endoscopy sparing by VariScreen: from 86.0% in compensated Child Pugh class A to 24.1% in Child-Pugh class C with ascites. CONCLUSION: VariScreen algorithm significantly reduced the missed LEV rate with ECE by 87%, ECE use by 38% and endoscopy requirement by 69%, and even 86% in compensated cirrhosis.

Collision avoidance between two walkers: role-dependent strategies.

This paper studies strategies for collision avoidance between two persons walking along crossing trajectories. It has been previously demonstrated that walkers are able to anticipate the risk of future collision and to react accordingly. The avoidance task has been described as a mutual control of the future distance of closest approach, MPD (i.e., Mininum Predicted Distance). In this paper, we studied the role of each walker in the task of controlling MPD. A specific question was: does the walker giving way (2nd at the crossing) and the one passing first set similar and coordinated strategies? To answer this question, we inspected the effect of motion adaptations on the future distance of closest approach. This analysis is relevant in the case of collision avoidance because subtle anticipatory behaviors or large last moment adaptations can finally yield the same result upon the final crossing distance. Results showed that collision avoidance is performed collaboratively and the crossing order impacts both the contribution and the strategies used: the participant giving way contributes more than the one passing first to avoid the collision. Both walkers reorient their path but the participant giving way also adapts his speed. Future work is planned to investigate the influence of crossing angle and TTC on adaptations as well as new types of interactions, such as intercepting or meeting tasks.

Minimal predicted distance: a common metric for collision avoidance during pairwise interactions between walkers.

This study investigated collision avoidance between two walkers by focusing on the conditions that lead to avoidance manoeuvres in locomotor trajectories. Following the hypothesis of a reciprocal interaction, we suggested a mutual variable as a continuous function of the two walkers' states, denoted minimum predicted distance (MPD). This function predicts the risk of collision, and its evolution over time captures the motion adaptations performed by the walkers. By groups of two, 30 walkers were assigned locomotion tasks which lead to potential collisions. Results showed that walkers adapted their motions only when required, i.e., when MPD is too low (<1 m). We concluded that walkers are able (i) to accurately estimate their reciprocal distance at the time the crossing will occur, and (ii) to mutually adapt this distance. Furthermore, the study of MPD evolution showed three successive phases in the avoidance interaction: observation where MPD(t) is constant, reaction where MPD(t) increases to acceptable values by adapting locomotion and regulation where MPD(t) reaches a plateau and slightly decreases. This final phase demonstrates that collision avoidance is actually performed with anticipation. Future work would consist in inspecting individual motion adaptations and relating them with the variations of MPD.

Intra-familial phenotypic heterogeneity in adult onset vanishing white matter disease.

Vanishing white matter (VWM) disease, also known as childhood ataxia with central nervous system hypomyelination (CACH) syndrome, is an autosomal recessive transmitted leukodystrophy. Classically characterised by early childhood onset, adult onset formed with slower progression have been recently recognized. The course of neurological impairment is usually progressive with possible occasional episodes of acute deterioration following febrile illnesses or head trauma. Neurological features are dominated by cerebellar ataxia and spasticity with relatively preserved mental abilities. Brain MRI shows diffuse abnormal signal of the cerebral white matter and cystic degeneration. Mutations in one of the genes coding for the five subunits of the translation factor eukaryotic initiation factor 2B (eIF2B) have been identified. We report here on two sisters affected by adult onset VWM with variable phenotypic expression. The proband is remarkable by the very late age of the disease onset (age of 42). A homozygous p.Arg113His mutation in the eIF2Bvarepsilon gene was identified. This mutation had been recurrently associated with adult onset VWM establishing phenotype-genotype correlations. We will show an important intra-familial phenotypic variability and discuss it in the light of recent molecular progresses. External precipitating factors are contributing for some of the differences observed.