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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.

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 β-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. [ABSTRACT FROM AUTHOR]

This is a reply to the comments made by Bogdanov et al on our paper entitled ‘A review on ion–ion plasmas created in weakly magnetized electronegative plasmas’. We have clarified some issues regarding the electronegative plasma stratification and the definition of an ion–ion plasma, and we discuss the issue of extracting negative ions from a steady-state ion–ion plasma formed at the periphery or downstream a magnetized electronegative plasma. [ABSTRACT FROM AUTHOR]

After a unilateral muscle exercise, the performance of the non-exercised contralateral limb muscle can be also impaired. This crossover fatigue phenomenon is still debated in the literature and very few studies have investigated the influence of eccentric contractions. This study was designed to assess neuromuscular adaptations involved in the crossover fatigue of the non-exercised contralateral knee flexor muscles. Seventeen healthy young men performed a unilateral submaximal eccentric exercise of the right knee flexors until a 20% reduction in maximal voluntary isometric contraction torque was attained in the exercised limb. Before (PRE), immediately after exercise cessation (POST) and 24 hours later (POST24), neuromuscular function and perceived muscle soreness were measured in both the exercised limb and non-exercised limb. In addition, global perceived fatigue was assessed at each measurement time. At POST, significant reductions in maximal voluntary isometric contraction were observed in the exercised limb (-28.1%, p < 0.001) and in the non-exercised limb (-8.5%, p < 0.05), evidencing crossover fatigue. At POST, voluntary activation decreased in the exercised limb only (-6.0%, p < 0.001), while electrically evoked potentiated doublet torque was impaired in both the exercised limb and the non-exercised limb (-11.6%, p = 0.001). In addition, global perceived fatigue significantly increased at POST (p < 0.001). At POST24, all measured variables returned to PRE values, except for perceived muscle soreness scores exhibiting greater values than PRE (p < 0.05). A possible cumulative interaction between peripheral alterations and global perceived fatigue may account for the immediate crossover fatigue observed in the non-exercised limb., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Gioda et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

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., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

Recent research has shown that inducing a negative stereotype toward women does not always decrease the subsequent motor performance of women, but can increase it, especially during endurance tasks. The mechanisms involved are nonetheless still poorly understood. The main aim of the present study was to investigate the effect of a negative stereotype toward women on men's and women's performance during an endurance task, and to analyze the neuropsychological mechanisms involved through motor-related cortical potentials and motivation toward men/women. Thirty-four participants were assigned to a negative stereotype toward women condition and a nullified-stereotype condition and performed 80 self-paced intermittent isometric elbow contractions at a moderate perceived intensity. Results showed that women performed better when assigned to the negative stereotype toward women condition, they were more motivated to outperform men, and their MRCP amplitudes were higher in this same condition over the prefrontal cortex (i.e., FP1 and FP2). Concerning men, they also performed better when the negative stereotype toward women was induced. However, no effect emerged on motivation toward women and MRCP amplitudes. This study showed that inducing a negative stereotype during an endurance task led to a performance increase in women, which is contrary to the stereotype threat theory, strengthening the idea of a task-dependency effect when inducing a negative stereotype. This performance improvement observed in women may be caused by increased motivation to outperform men and a planning of the upcoming movement. Concerning men, more research is needed to clarify the mechanisms involved in such performance improvement., Competing Interests: Declaration of competing interest The authors declared no potential conflicts of interests with respect to the authorship and/or publication of this article., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

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., (© 2020 The Author(s). Published by IOP Publishing Ltd.)

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., (© 2019 The Author(s).)

Single frequency, geometrically symmetric Radio-Frequency (rf) driven atmospheric pressure plasmas exhibit temporally and spatially symmetric patterns of electron heating, and consequently, charged particle densities and fluxes. Using a combination of phase-resolved optical emission spectroscopy and kinetic plasma simulations, we demonstrate that tailored voltage waveforms consisting of multiple rf harmonics induce targeted disruption of these symmetries. This confines the electron heating to small regions of time and space and enables the electron energy distribution function to be tailored.

Background: Impairments resulting from hemiparetic stroke lead to persistent difficulties with walking. Abnormal co-contraction patterns of lower limb muscles might be a compensatory mechanism to deal with its resulting gait impairments., Aim: The aim of this study was to assess muscle co-contraction obtained from muscle moments in chronic hemiparetic patients presenting a stiff-knee gait (SKG) during walking., Design: Cross-sectional study., Setting: Clinical movement analysis laboratory in a health center and a community hospital., Population: Twelve hemiparetic patients 6 months' post-stroke (mean±SD age 49.3±12.5) walking with a SKG and twelve healthy adults (mean±SD age 23.5±7.7)., Methods: Hemiparetic patients walked at their natural gait speed while healthy adults walked at their natural and slow gait speed. Spatiotemporal, kinetic and kinematic gait parameters were determined for both lower limbs. Co-Contraction Index at the knee and the ankle was calculated from muscle moments estimated using an EMG-driven model during the first (DS1) and second (DS2) double support and the single support (SS) phases and the swing phase (SW)., Results: The results revealed that chronic stroke patients have reduced ankle co-contraction and increased knee co-contraction during DS1 phase, increased ankle co-contraction during DS2 phase and increased knee co-contraction during SW phase on the paretic side. On the non-paretic side, muscle co-contraction was higher at the knee during SS phase., Conclusions: Increased co-contraction during walking in both the paretic and the non-paretic side, in patients with hemiparesis exhibiting a SKG, might be an adaptive strategy to increase walking stability, as it may be related to spasticity, but also could result in a high metabolic cost., Clinical Rehabilitation Impact: The information obtained in this study may be used to support rehabilitation programs focusing on the selectivity of movement control such as strength or power training.

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., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The use of Serious Games (SG) in the health domain is expanding. In the field of neurodegenerative disorders (ND) such as Alzheimer's disease, SG are currently employed both to support and improve the assessment of different functional and cognitive abilities, and to provide alternative solutions for patients' treatment, stimulation, and rehabilitation. As the field is quite young, recommendations on the use of SG in people with ND are still rare. In 2014 we proposed some initial recommendations (Robert et al., 2014). The aim of the present work was to update them, thanks to opinions gathered by experts in the field during an expert Delphi panel. Results confirmed that SG are adapted to elderly people with mild cognitive impairment (MCI) and dementia, and can be employed for several purposes, including assessment, stimulation, and improving wellbeing, with some differences depending on the population (e.g., physical stimulation may be better suited for people with MCI). SG are more adapted for use with trained caregivers (both at home and in clinical settings), with a frequency ranging from 2 to 4 times a week. Importantly, the target of SG, their frequency of use and the context in which they are played depend on the SG typology (e.g., Exergame, cognitive game), and should be personalized with the help of a clinician.

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., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

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., (Copyright © 2017 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.)

The process of learning to walk is ongoing throughout childhood. The Gait Variability Index (GVI; A. Gouelle et al., 2013) has been proposed to quantify the variability of spatiotemporal parameters (STP) during gait. The authors' aim was to evaluate the GVI and STP of healthy children and teenagers to (a) determine changes in the GVI with age and to derive normal values in children and (b) to evaluate the influence of STP on the GVI. A total of 140 typically developing children from 1 to 17 years old were categorized into 7 groups of 20 based on age. Spatiotemporal gait parameters were recorded using an electronic walkway. GVI increased and STP changed with age. In the children-teenagers group, the GVI was positively related to step length, speed, and negatively to cadence. Following normalization by lower limb length, correlations were no longer significant. In contrast, raw base of support was not correlated with the GVI but normalized base of support was. A multiple linear regression showed that only age had a direct impact on the GVI, indicating that gait continues to change after 6-7 years. These changes were only demonstrated by the GVI, highlighting its usefulness for the evaluation of gait in young populations.

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., (Copyright © 2015 Elsevier Masson SAS. All rights reserved.)

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., (Copyright © 2014 Elsevier B.V. All rights reserved.)

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., (Copyright © 2012 Elsevier Masson SAS. All rights reserved.)

The aim of this article is to elaborate a general framework for modeling dual opposition activities, or more generally, dual interaction. The main hypothesis is that opposition behavior can be measured directly from a global variable and that the relative distance between the two subjects can be this parameter. Moreover, this parameter should be considered as multidimensional parameter depending not only on the dynamics of the subjects but also on the "internal" parameters of the subjects, such as sociological and/or emotional states. Standard and simple mechanical formalization will be used to model this multifactorial distance. To illustrate such a general modeling methodology, this model was compared with actual data from an opposition activity like Japanese fencing (kendo). This model captures not only coupled coordination, but more generally interaction in two-subject activities.

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.

The ability to estimate distance walked when blindfolded is associated with the vestibular, proprioceptive and (loco-)motor systems. In this study, we examined subjects' ability to walk when blindfolded to a previously seen target. We examined whether there is a difference of performance in path integration between athletes and non-athletes. Two groups of healthy volunteers took part in this experiment: 21 athletes and 20 non-athletes. Subjects were asked to walk at three different velocities (slow, normal, fast) to a target (10 m in front of them) that they had seen before being blindfolded. Increase in velocity was associated with a decrease in the distance walked for both groups. Both groups were accurate at normal velocities. Athletes were also accurate at fast velocities whereas non-athletes undershot the target. In both groups, accuracy considerably decreased at slow velocities. It seems that our perceptual system can adapt to different velocities (normal, fast) but is most strongly disrupted at low velocity. When attempting to modify walking velocity, step length is also modified, playing a determining role in the estimation of distance.

Objectives: Parabens are currently used as antibacterial preservatives in pharmaceutical, cosmetic and food products but there are no precise data concerning their activity on bacterial membranes., Methods: We analysed the cytoplasmic potassium release during propyl paraben addition by using a selective electrode. Various conditions were assayed to investigate the bacterial paraben susceptibility. We compared the activity of propyl paraben with the activities of colicin A and polymyxin B., Results: Propyl paraben induced potassium efflux that was related to the porin expression in the bacterial outer membrane. In addition, the presence of spermine, previously described as an efficient OmpF channel-blocker, protected susceptible cells against paraben activity., Conclusions: Propyl paraben induced potassium release in susceptible Escherichia coli cells similar to that observed with polymyxin B. Moreover, this efflux depended on porin channel activity. This permeabilizing effect is probably related to antibacterial properties of paraben molecules.

Beta-lactams use aqueous channels of porins to penetrate Gram-negative bacteria. The L3 loop of Escherichia coli OmpF porin is a key feature that actively contributes to both channel size and electrostatic properties. Acid residues D113, E117, and D121 are responsible for the negative part of the local electrostatic field on this loop. Two substitutions, D113A and D121A, located in the negatively charged cluster of the OmpF eyelet, increase the likelihood of producing bacteria susceptible to several beta-lactams. D113A substitution results in an increase in the ampicillin, cefoxitin, and ceftazidime susceptibility. Molecular modeling suggests that the charges harbored by the beta-lactam molecules interact with the charged residues located inside the porin eyelet.

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., (Copyright 2004 Elsevier B.V.)

In Enterobacter aerogenes and Klebsiella pneumoniae, efflux provides efficient extrusion of antibiotics and contributes to the multidrug resistance phenotype. One of the alkoxyquinoline derivatives studied here, 2,8-dimethyl-4-(2'-pyrrolidinoethyl)-oxyquinoline, restores noticeable drug susceptibility to resistant clinical strains. Analyses of energy-dependent chloramphenicol efflux indicate that this compound inhibits the efflux pump mechanism and improves the activity of structurally unrelated antibiotics on multidrug-resistant E. aerogenes and K. pneumoniae isolates.

The L3 loop is an important feature of the OmpF porin structure, contributing to both channel size and electrostatic properties. Colicins A and N, spermine, and antibiotics that use OmpF to penetrate the cell, were used to investigate the structure-function relationships of L3. Spermine was found to protect efficiently cells expressing wild-type OmpF from colicin action. Among other solutes, sugars had minor effects on colicin A activity, whereas competitions between colicin A and antibiotic fluxes were observed. Among the antibiotics tested, cefepime appeared the most efficient. Escherichia coli cells expressing various OmpF proteins mutated in the eyelet were tested for their susceptibility to colicin A, and resistant strains were found only among L3 mutants. Mutations at residues 119 and 120 were the most effective at conferring resistance to colicin A, probably due to epitope structure alteration, as revealed by a specific antipeptide. More detailed information was obtained on mutants D113A and D121A, by focusing on the kinetics of colicin A and colicin N activities through measurements of potassium efflux. D113 appeared to play an essential role for colicin A activity, whereas colicin N activity was more dependent on D121 than on D113.

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.