Identification of human balance control responses to visual inputs using virtual reality.

Human upright balance is maintained through feedback mechanisms that use a variety of sensory modalities. Vision senses information about the position and velocity of the visual surround motion to improve balance by reducing the sway evoked by external disturbances. This study characterized the effects of visual information on human anterior-posterior body sway in upright stance by presenting perturbations through a virtual reality system. This made it possible to use a new visual perturbation signal, based on trapezoidal velocity pulses, whose amplitude and velocity could be controlled separately. To date, the influences of visual field position and velocity have only been studied independently due to the experimental limitations. The hip displacement, ankle torques, shank angles, and surface EMGs of four major ankle muscles were measured bilaterally as outputs. We found that the root mean square (RMS) hip displacement (body angle) increased systematically with visual input amplitude. However, for each amplitude, the RMS body angle increased when input velocity was changed from 2 to 5 degrees per second (dps) and then decreased from 5 to 10 dps. Spectral analysis was used to compute frequency response over a frequency range from 0.04 to 0.6 Hz. The gain of body sway relative to the perturbation increased with frequency, whereas the coherence declined. Moreover, as the stimulus amplitude increased, the gain generally decreased, whereas the mean coherence values always increased. The mean gains and mean coherence values were greatest for the velocity of 5 dps. This study presents a novel experimental approach to study human postural control and augments our knowledge of how visual information is processed in the central nervous system to maintain balance.NEW & NOTEWORTHY In this paper, we developed a new methodological approach to study the effects of visual information on dynamic body sway. We used VR to apply visual perturbations to induce AP body sway. We designed a new visual stimulus waveform based on trapezoidal velocity pulses whose peak-to-peak amplitude and velocity could be modulated independently. Subsequently, we investigated how the amplitude and velocity of visual field motion influence the postural responses evoked in healthy adults.

Antibacterial, anti-swarming and anti-biofilm formation activities of Chamaemelum nobile against Pseudomonas aeruginosa

Chamomile ( Chamaemelum nobile ) is widely used throughout the world, and has anti-inflammatory, deodorant, bacteriostatic, antimicrobial, carminative, sedative, antiseptic, anti-catarrhal, and spasmolytic properties. Because of the increasing incidence of drug-resistant bacteria, the development of natural antibacterial sources such as medical herbs for the treatment of infectious diseases is necessary. Extracts from different plant parts such as the leaves, flowers, fruit, and bark of Combretum albiflorum, Laurus nobilis , and Sonchus oleraceus were found to possess anti-quorum sensing (QS) activities. In this study, we evaluated the effect of C. nobile against Pseudomonas aeruginosa biofilm formation

Determination of the influence of walking with orthosis on bone osteoporosis in paraplegic subjects based on the loads transmitted through the body.

BACKGROUND: Spinal cord injury is a damage to spinal cord that results in loss of function and mobility below the level of injury. The patients use various orthoses to improve their general health, to decrease bone osteoporosis, and to improve bone mineral density. It was controversial if how much percentage of the loads applied on an orthosis and body complex is transmitted by orthosis. Therefore, it was aimed to determine the magnitude of the loads transmitted by orthosis to find the influence of walking with orthosis on bone mineral density. METHODS: Three spinal cord injured subjects were recruited in this study. They were trained to walk with a reciprocal gait orthosis. The loads applied on the hip joint of the orthosis and body complex, anatomy and orthosis were measured by use of strain gauges and motion analysis system. FINDINGS: The mean values of the force and moments transmitted by the orthosis were significantly less than those of the complex. The mean values of adduction moment transmitted through the orthosis and body complex and by the orthosis structure were 1.06 and 0.49N·m/body weight, respectively. INTERPRETATION: As a higher percentage of loads were transmitted by body than the orthosis, it can be concluded that walking with orthosis could improve bone mineral density, due to the role of bone in transmission of the loads. Therefore, it is recommended that spinal cord injured subjects walk with an orthosis in order to reduce bone osteoporosis, especially for a long period of time.