The effect of tibialis anterior weakness on foot drop and toe clearance in patients with facioscapulohumeral dystrophy.

BACKGROUND: Facioscapulohumeral dystrophy is a genetic disease characterized by progressive muscle weakness leading to a complex combination of postural instability, foot drop during swing and compensatory strategies during gait that have been related to an increased risk of falling. The aim is to assess the effect of tibialis anterior muscle weakness on foot drop and minimum toe clearance of patients with facioscapulohumeral dystrophy during gait. METHODS: Eight patients allocated to a subgroup depending on the severity of tibialis anterior muscle weakness, assessed by manual muscle testing (i.e., severe and mild weakness), and eight matched control participants underwent gait analysis at self-selected walking speeds. FINDINGS: Walking speed, for all facioscapulohumeral dystrophy patients, and step length, for patients with severe weakness only, were significantly decreased compared to control participants. Minimum toe clearance was similar across all groups, but its variability was increased only for patients with severe weakness. A greater foot drop was systematically observed for patients with severe weakness during swing and only in late swing for patients with mild weakness. Individual strategies to compensate for foot drop remain unclear and may depend on other muscle impairment variability. INTERPRETATION: Although all patients were able to control the average height of their foot trajectory during swing, patients with severe tibialis anterior muscle weakness exhibited increased foot drop and minimum toe clearance variability. Manual muscle testing is a simple, cheap and effective method to assess tibialis anterior muscle weakness and seems promising to identify facioscapulohumeral dystrophy patients with an increased risk of tripping.

Reproducibility of 'COST reference microplasma jets'.

Atmospheric pressure plasmas have been ground-breaking for plasma science and technologies, due to their significant application potential in many fields, including medicinal, biological, and environmental applications. This is predominantly due to their efficient production and delivery of chemically reactive species under ambient conditions. One of the challenges in progressing the field is comparing plasma sources and results across the community and the literature. To address this a reference plasma source was established during the 'biomedical applications of atmospheric pressure plasmas' EU COST Action MP1101. It is crucial that reference sources are reproducible. Here, we present the reproducibility and variance across multiple sources through examining various characteristics, including: absolute atomic oxygen densities, absolute ozone densities, electrical characteristics, optical emission spectroscopy, temperature measurements, and bactericidal activity. The measurements demonstrate that the tested COST jets are mainly reproducible within the intrinsic uncertainty of each measurement technique.

Modification of knee flexion during walking with use of a real-time personalized avatar.

Visual feedback is used in different research areas, including clinical science and neuroscience. In this study, we investigated the influence of the visualization of a real-time personalized avatar on gait parameters, focusing on knee flexion during the swing phase. We also studied the impact of the modification of avatar's knee amplitude on kinematic of the knee of healthy subjects. For this purpose, we used an immersive reality treadmill equipment and developed a 3D avatar, with instantly modifiable parameters for knee flexion and extension (acceleration or deceleration). Fourteen healthy young adults, equipped with motion capture markers, were asked to walk at a self-selected pace on the treadmill. A real-time 3D image of their lower limbs was modelized and projected on the screen ahead of them, as if in a walking motion from left to right. The subjects were instructed to continue walking. When we initiated an increase in the knee flexion of the avatar, we observed a similar increase in the subjects' knee flexion. No significant results were observed when the modification involved a decrease in knee flexion. The results and their significance are discussed using theories encompassing empathy, sympathy and sensory re-calibration. The prospect of using this type of modified avatar for stroke rehabilitation is discussed.

Effect of robotic-assisted gait rehabilitation on dynamic equilibrium control in the gait of children with cerebral palsy.

Due to the intensity and repetition of movement, roboticassisted gait training therapy could have a beneficial effect on the recovery and improvement of postural and locomotor functions of the patient. This study sought to highlight the effects of robotic-assisted gait rehabilitation in gait of children with Cerebral Palsy (CP). We analyzed the different strategies before and after this rehabilitation which was used in order to generate forward motion while maintaining balance. Data were collected by a motion analysis system (Vicon® - Oxford Metrics, Oxford, UK). The children were divided into two groups in such a way as to obtain a randomized controlled population: i) a group of fourteen children (Treated Group) underwent 20 sessions of roboticassisted gait training therapy using the driven gait orthosis Lokomat®Pediatric (Hocoma AG, Volketswil, Switzerland) compared to ii) a group of sixteen children without sessions of Lokomat®Pediatric (Control Group). Significant differences are observed for the TG between the preand post-test values of the locomotor parameters and of the kinetic data of the propulsive forces of the Center of Mass (COM) and of the Center of Pressure (COP) dynamic trajectory. This first study, although performed on a limited number of patients, shows the usefulness of this robotic gait rehabilitation mainly in the balance control in gait. Indeed after this rehabilitation, these children improve their gait that is especially characterized by a more appropriate time lag between the time instant of COM-COP trajectory divergence and the time instant when the forward propulsive forces became apparent.

Comparison of methodologies to assess muscle co-contraction during gait.

The aim of this study was to compare co-contraction index (CCI) computed from muscle moments to different co-activation indexes (Co-Act) derived from EMG data at the ankle and the knee joint during gait. An EMG-driven model was used to estimate muscle moments during over-ground walking gait at a self-selected velocity from twelve healthy subjects. The CCI calculated from muscle moments was compared with three Co-Acts estimated from the normalized EMG data. The co-activation methods produced lower values than the CCI during the first double-support and the swing phase at the ankle joint and during the stance phase at the knee joint. The co-activation methods trend is to underestimate the simultaneous action of agonist and antagonist contraction. Because the EMG-driven model included the muscle mechanical properties (e.g. force-length-velocity relationship) and muscle moment-arm, the co-contraction based on major agonist and antagonist muscle moment may provide a more confident description of muscle action compared to co-activation indexes.

Robotic-assisted gait training improves walking abilities in diplegic children with cerebral palsy.

The robotic-assisted gait training therapy (RAGT), based on intensity and repetition of movement, presents beneficial effects on recovery and improvement of postural and locomotor functions of the patient. This study sought to highlight the effect of this RAGT on the dynamic equilibrium control during walking in children with Cerebral Palsy (CP) by analyzing the different postural strategies of the fullbody (upper/lower body) before and after this RAGT in order to generate forward motion while maintaining balance. Data were collected by a motion analysis system (Vicon® - Oxford Metrics). Thirty children with bilateral spastic CP were evaluated using a full-body marker set which allows assessing both the lower and upper limb kinematics. The children were divided into two groups in such a way as to obtain a randomized controlled population: i) a group of fourteen children (Treated Group) underwent 20 sessions of RAGT using the driven gait orthosis Lokomat®Pediatric (Hocoma) compared to ii) a group of sixteen children without sessions of Lokomat®Pediatric (Control Group) receiving only daily physiotherapy. Significant improvements are observed between the TG pre- and post-test values of i) the kinematic data of the full-body in the sagittal and frontal planes and ii) the Gross Motor Function Measure test (D and E). This study shows the usefulness of this RAGT mainly in the balance control in gait. Indeed, the Treated Group use new dynamic strategies of gait that are especially characterized by a more appropriate control of the upper body associated with an improvement of the lower limbs kinematics.

Effects of robotic gait rehabilitation on biomechanical parameters in the chronic hemiplegic patients.

Hemiplegia is a more or less complete loss of hemibody voluntary motricity following a brain injury, usually resulting in alterations of the locomotor system with persistent disorders of movement and posture. We were interested in studying the gait pattern called "stiff knee gait" with the main objective to highlight the role of a robotic rehabilitation in improving or modifying/changing the walking pattern in adults with chronic hemiplegic disorders. Data were collected by a motion analysis system (Vicon(®)--Oxford Metrics, Oxford, UK) in order to achieve a Clinical Gait Analysis before and after a robotic gait rehabilitation (Lokomat(®)). Four intensive sessions per weeks during five weeks were performed by ten chronic hemiplegic adults. The results show a significant improvement in locomotor parameters (walking speed, step length, single and double support time) and in the knee kinematics. This first study provides experimental evidence of the importance and usefulness of the robotic rehabilitation as an aid in the rehabilitation of gait pattern in adults with chronic hemiplegia.

Balance control in gait children with cerebral palsy.

This study sought to highlight the balance control process during gait in children with cerebral palsy (CP) by analyzing the different strategies used in order to generate forward motion while maintaining balance. Data were collected using a motion analysis system in order to provide a clinical gait analysis for 16 children with CP and 16 children with typical development. Significant differences between the two groups are observed in terms of kinetic data of the propulsive forces of the center of mass (COM) and of the center of pressure (COP) dynamic trajectory and for locomotor parameters. The imbalance generated by divergent trajectories of COM and COP produce the propulsive forces responsible for human gait initiation. Moreover, we observe in children with CP an "en bloc" postural strategy resulting in increasing divergence between trajectories of COM-COP. This particular strategy of the children with CP is characterized by a greater time duration between the moment of COM-COP trajectory divergence and the moment where the forward propulsive forces became apparent.

The role of head stabilization in locomotion in children with cerebral palsy.

OBJECTIVE: The objective of the present study was to highlight the role of head stabilization and to analyze multisegment head-trunk coordination during gait in children with cerebral palsy (CP). MATERIAL AND METHOD: Postural control was measured and compared in a group of 16 CP subjects and a control group of 16 healthy subjects. The subjects had to walk along an out-and-back course at their freely chosen gait speed. For each gait cycle, motion analysis techniques were used to calculate the amplitude of the head angle (relative to the trunk) in the sagittal and frontal planes. RESULTS: Kinematic analysis revealed a number of significant intergroup differences, with a more pronounced variation in the head angle (relative to the trunk) in the CP group than in the control group. There were no significant intergroup differences in terms of the angular amplitude of the head in the sagittal plane. CONCLUSION: The greater variability of the head angle in the frontal plane in the CP subjects might reflect the presence of greater head roll as a compensatory strategy. These finding suggest that the clinical evaluation of posture during gait in children with CP should be reconsidered.

Enterobacter gergoviae and the prevalence of efflux in parabens resistance.

OBJECTIVES: In order to characterize the mechanism involved in parabens resistance, we studied 13 Enterobacter gergoviae collected from diverse cosmetic formulations containing parabens as preservatives and 10 isolates from clinical or industrial sources. METHODS: RAPD and ERIC-PCR were employed and compared for the epidemiological typing. To study antibiotic and paraben susceptibility, the standard disc diffusion method and the 2-fold dilution method in Luria-Bertani medium were used. Characterization of porins was performed using immunodetection with polyclonal antibodies. Resistance mechanisms against parabens membrane permeabilization were evaluated by measuring K(+) efflux using a specific electrode. mar regulon identification and comparison were carried out. RESULTS: Epidemiological typing confirmed that most of the cosmetic formulations were contaminated by unrelated strains. All of the E. gergoviae strains presented high methylparaben MICs, ranging from 1 to 3.8 g/L, values that were 2-5 times higher than for Escherichia coli or Enterobacter aerogenes, even in strains overexpressing MarA. These MICs decreased in the presence of phenylalanine arginine beta-naphthylamide, pinpointing efflux as a major mechanism of parabens resistance even in E. gergoviae clinical strains. CONCLUSIONS: This is the first report showing the role of active efflux in the parabens resistance in E. gergoviae, a mechanism that may explain its frequent isolation in parabens-containing cosmetics compared with other enterobacterial species. Paraben efflux seems to be regulated by a mar-independent process in E. gergoviae.

Multifactorial interactions involved in linear self-transport distance estimate: a place for time.

As the vestibular system is the only sensory organ whose primary function is self-motion detection, we examined the conditions under which the otoliths, which detect the linear acceleration of the head, could be used to estimate traveled distance. In order to isolate the contribution of the otoliths (with the somatosensory system) from contributions of the visual and motor systems subjects were transported in darkness. We initially hypothesized that self-transport with continuously varying linear velocity should facilitate distance computation by continuously stimulating the otoliths, and that active control of self-motion should also help subjects estimate the distance traveled. However, it was found that the distance covered during self-motion is actually better estimated when transport velocity is quasi-constant. Nevertheless, such estimates strongly depend upon velocity magnitude; subjects show an idiosyncratic preferred self-motion velocity for which distance measurements are most accurate. Furthermore, the active control of self-transport improves estimates of self-motion mainly because the subjects can then adopt a constant velocity, and more precisely their preferred one. It was finally found that subjects mentally count in order to assess their displacement length, and that time perception is indeed disturbed by varying self-motion velocity.

Imipenem resistance in Salmonella enterica serovar Wien related to porin loss and CMY-4 beta-lactamase production.

Two multidrug-resistant Salmonella enterica serovar Wien strains (SW468 and SW1107) were isolated in 2001 in Tunis. Both strains produced the beta-lactamases TEM-1, SHV-2a, and CMY-4, whereas strain SW1107 also produced the beta-lactamase CTX-M-3. The imipenem-resistant strain (SW468) was totally devoid of the OmpF-immunorelated porin. Imipenem resistance was shown as being related to porin loss and CMY-4 beta-lactamase production.