In vitro and in vivo synthesis of the hepatitis B virus surface antigen and of the receptor for polymerized human serum albumin from recombinant human adenoviruses.

We have developed an adenovirus vector to express foreign proteins under the control of the adenovirus E1a promoter. Two recombinant plasmids, harbouring either the S gene or the pre-S2 region and the S gene of hepatitis B virus under the control of the E1a promoter, were used to construct two recombinant adenoviruses. These two viruses direct the synthesis of hepatitis B virus surface antigen (HBsAg) particles during the time course of an infectious cycle. When the pre-S2 region is present in the constructed virus, the synthesis of particles carrying the receptor for polymerized human serum albumin (pHSA) is observed. Moreover, the inoculation of rabbits with this latter purified recombinant adenovirus elicits the production of antibodies that react with both HBsAg and pHSA receptor

''How the ankle joint angle alters the antagonist and agonist torques during maximal efforts in dorsi- and plantar flexion''

International audience''The aim of this study was to assess, via an EMG bio-feedback method, the ankle joint angle effect on the agonist and antagonist torques in plantar- (PF) and dorsi-flexion (DF). The isometric PF and DF maximal voluntary contractions (MVCs) torques were measured simultaneously with surface EMG activity of triceps surae (TS) and tibialis anterior (TA) muscles in 12 young adults (mean age 27) at five different ankle joint angles. Our results showed that: (i) The coactivation level does not properly reflect the mechanical effect of the antagonist muscle, (ii) TS antagonist torque significantly altered the DF MVC-angle relationship, whereas TA antagonist torque did not influence this MVC-angle relationship in PF. The alteration of the MVC with angular position was due, in part, to the coactivation phenomenon in DF, but not in PF. Thenceforth, when investigating the torque at the ankle joint, it is necessary to take into account both agonist and antagonist torque modifications with ankle joint angle.'

Quantifying Paddling Kinematics through Muscle Activation and Whole Body Coordination during Maximal Sprints of Different Durations on a Kayak Ergometer: A Pilot Study

Paddling technique and stroke kinematics are important performance factors in flatwater sprint kayaking and entail significant energetic demands and a high strength from the muscles of the trunk and upper limbs. The various distances completed (from 200 m to 1000 m) require the athletes to optimize their pacing strategy, to maximize power output distribution throughout the race. This study aimed to characterize paddling technique and stroke kinematics during two maximal sprints of different duration. Nine nationally-trained participants (2 females, age: 18 ± 3 years; BMI: 22.2 ± 2.0 Kg m−1) performed 40 s and 4 min sprints at maximal intensity on a kayak ergometer. The main findings demonstrated a significantly greater mean stroke power (237 ± 80 W vs. 170 ± 48 W; p < 0.013) and rate (131 ± 8 spm vs. 109 ± 7 spm; p < 0.001) during the 40 s sprint compared to the 4 min sprint. Athletes used an all-out strategy for the 40 s exercise and a parabolic-shape strategy during the 4 min exercise. Despite the different strategies implemented and the higher muscular activation during the 40 s sprint, no change in paddling technique and body coordination occurred during the sprints. The findings of the present study suggest that the athletes constructed a well-defined profile that was not affected by fatigue, despite a decrease in power output during the all-out strategy. In addition, they regulated their paddling kinematics during the longer exercises, with no change in paddling technique and body coordination

Motor resonance mechanisms are preserved in Alzheimer's disease patients

This study aimed to better characterize the sensorimotor mechanisms underlying motor resonance, namely the relationship between motion perception and movement production in patients suffering from Alzheimer's disease (AD). This work first gives a kinematic description of AD patients' upper limb movements, then it presents a simple paradigm in which a dot with different velocities is moved in front of the participant who is instructed to point to its final position when it stopped. AD patients' actions, as well as healthy elderly participants, were similarly influenced by the dot velocity, suggesting that motor resonance mechanisms are not prevented by pathology. In contrast, only patients had anticipatory motor response: i.e. they started moving before the end of the stimulus motion, unlike what was requested by the experimenter. While the automatic imitation of the stimulus suggests an intact ability to match the internal motor representations with that of the visual model, the uncontrolled motion initiation would indicate AD patients' deficiency to voluntarily inhibit response production. These findings might open new clinical perspectives suggesting innovative techniques in training programs for people with dementia. In particular, the preservation of the motor resonance mechanisms, not dependent on conscious awareness, constitutes an intact basis upon which clinicians could model both physical and cognitive interventions for healthy elderly and AD patients. Furthermore, the evaluation of the inhibitory functions, less sensitive to the level of education than other methods, might be useful for screening test combined with the traditional AD techniques. However, further investigations to understand if this feature is specific to AD or is present also in other neurodegenerative diseases are needed. \ua9 2012 IBRO

Pratiques performatives

À notre époque, les nouvelles technologies contribuent largement à l'évolution des langages scéniques modifiant profondément les conditions de représentation et intensifiant toujours davantage les effets de présence et les effets de réel. Ces technologies sont souvent liées à l'émergence de nouvelles formes scéniques qui transgressent les limites des disciplines et se caractérisent par des spectacles à l'identité instable, mouvante, en perpétuelle redéfinition. Projections, installations interactives, environnements immersifs, spectacles sur la toile, les sens(ations) sont plus que jamais sollicité(e)s. Le performeur y est confronté à un Autre virtuel, à la fois personnage et partenaire. Quant au corps, charnel, physique, palpable, il constitue encore la trace incontestée de l'homme dans ces espaces où la déréalisation fait loi. Contre-point d'une culture du virtuel, le corps semble rester au cœur des dispositifs (scénique, interactif, immersif). Quel(s) corps ces œuvres convoquent-elles ? Comment ces dernières renouvellent-elles la dynamique entre performeurs, spectateurs et dispositifs ? Quelles sont les diverses modalités d'interpénétration entre le virtuel et le réel dans ces formes d'art ? Voilà autant de questions auxquelles ce livre tente de répondre. Celles-ci sont le résultat de plusieurs années de recherche consacrées aux effets de présence et aux effets de réel. C'est le résultat de ces explorations effectuées par l'équipe de recherche « Performativité et effets de présence » de l'université du Québec à Montréal (sous la direction de Josette Féral et Louise Poissant), que le lecteur pourra trouver dans ce premier volume consacré au corps. Body Remix reprend le titre du spectacle de la chorégraphe Marie Chouinard présenté en 2005