Detection of locomotion deficit in a post-traumatic syringomyelia rat model using automated gait analysis technique

Syringomyelia (SM) is a spinal cord disorder in which a cyst (syrinx) filled with fluid forms in the spinal cord post-injury/disease, in patients syrinx symptoms include loss of pain and temperature sensation or locomotion deficit. Currently, there are no small animal models and connected tools to help study the functional impacts of SM. The objective of this study was to determine the detectability of subtle locomotion deficits due to syrinx formation/expansion in post-traumatic syringomyelia (PTSM) rat model using the recently reported method of Gait Analysis Instrumentation, and Technology Optimized for Rodents (GAITOR) with Automated Gait Analysis Through Hues and Areas (AGATHA) technique. First videos of the rats were collected while walking in an arena (using GAITOR) followed by extracting meaningful locomotion information from collected videos using AGATHA protocol. PTSM injured rats demonstrated detectable locomotion deficits in terms of duty factor imbalance, paw placement accuracy, step contact width, stride length, and phase dispersion parameters compared to uninjured rats due to SM. We concluded that this technique could detect mild and subtle locomotion deficits associated with PTSM injury, which also in future work could be used further to monitor locomotion responses after different treatment strategies for SM.

Adaptation of the Compensatory Stepping Response Following Predictable and Unpredictable Perturbation Training

BackgroundEffective training of the backward step response could be beneficial to improve postural stability and prevent falls. Unpredicted perturbation-based balance training (PBT), widely known as compensatory-step training, may enhance the fear of falling and the patterns of postural muscle co-contraction. Contrastingly, PBT with predictable direction or both direction and timing would suppress the fear and the co-contraction patterns during training, but the efficacy of predictable PBT for unpredictable perturbations is still unknown.ObjectiveTo compare the adaptation effects of compensatory-step training with and without predictable perturbations on backward stepping against unpredictable perturbations.MethodsThirty-three healthy young adults were randomly assigned to one of the following step training groups: Unpredicted, Predicted, and Self-initiated. In training sessions, participants were perturbed to induce a compensatory step with (Predicted group) or without (Unpredicted group) knowledge of the perturbation’s direction or while knowing both the direction and timing of the perturbation (Self-initiated group). In test sessions (pre- and post-training), participants were instructed to recover their postural stability in response to an unpredicted perturbation. The margin of stability (MOS), center of mass (COM) shift, and step characteristics were measured during a backward step in both test and training sessions.ResultsAll three groups showed a significant increase in the step length and velocity in the post-training sessions compared to those in the pre-training sessions. Moreover, in the Unpredicted and Predicted groups, but not in the Self-initiated group, the MOS at step contact was significantly increased following the training session. In addition, the Self-initiated group showed a significant increase in COM shift at 50 ms after slip onset during training compared to the Unpredicted and Predicted groups.ConclusionUnpredicted and predicted PBT improve step characteristics during backward stepping against unpredictable perturbations. Moreover, the unpredictable PBT and PBT with direction-predictable perturbations enhance the feedback postural control reflected as the postural stability at step contact.

Detection of Locomotion Deficit in a Post-Traumatic Syringomyelia Rat Model Using Automated Gait Analysis Technique

Syringomyelia (SM) is a spinal cord disorder in which a cyst (syrinx) filled with fluid forms in the spinal cord post-injury/disease, in patients syrinx symptoms include loss of pain and temperature sensitivity or locomotion deficit. Currently, there are no small animal models and connected tools to help study the functional impacts of SM. The objective of this study was to determine the detectability of subtle locomotion deficits due to syrinx formation/expansion in post-traumatic syringomyelia (PTSM) rat model using the recently reported method of gait analysis instrumentation, and technology optimized for rodents (GAITOR) with automated gait analysis through hues and areas (AGATHA) technique. First videos of the rats were collected while walking in an arena (using GAITOR) followed by extracting meaningful locomotion information from collected videos (using AGATHA software). PTSM injured rats demonstrated detectable locomotion deficits in terms of duty factor imbalance, paw placement accuracy, step contact width, stride length, and phase dispersion parameters compared to uninjured rats due to SM. We concluded that this technique could detect mild and subtle locomotion deficits associated with PTSM injury, which also in future work could be used further to monitor locomotion responses after different treatment strategies for SM.

Possibility of Using Nuclear Track Membrane for Ophthalmology

This work is devoted to study the possibility of using a nuclear track membrane for ophthalmology in epithelial-endothelial corneal dystrophy treatment. Experiments were conducted using the track membrane “TOMTREK” based on polyethylenterephthalate (PET) with pores diameters (0.2-0.8)micron and (5x106-2x109) pores/cm2 density. The pores were formed by irradiating the polymer PET 40Ar+8 ions with energy 41.5 MeV. After irradiation, the membrane was chemically treated in the alkaline solution. Imparting hydrorhilicity membrane was the next step. Contact angle of the wettability the surface track membrane was measured just after the chemical treatment in NaOH and after 10 hours in air. The surface had been processed by the plasma self-sustained volume discharge to give the surface the hydrorhilic properties of the membrane. The maximum voltage on plasma discharge was 20-22 kV. The energy density in the discharge was 6·10-4 J/cm2 per pulse. Pulse repetition rate was 103 s-1. Samples of 6x6 cm were attached in a special rotating device. Thus, the effects were both surfaces of the membrane. After surface treatment, TM samples were placed in plastic bags. After a night contact angle of wetting was measured with these samples. Disks treating by the plasma were cut. The disk’s diameter was 6-8 cm. The edges of the disks were incised and processed with hot temperature in order to obtain the model of an appropriate shape. It was a shape of a truncated sphere with a certain radius of curvature. Then, the membrane was sterilized and implanted into the anterior chamber of the pig’s eye. Thus, we tested the methods of barrier keratoplasty using the nuclear track membrane.

Dynamics Simulations of a Graphite Block Under Longitudinal Impact

Graphite blocks are important core components of the high temperature gas-cooled reactor. As these blocks are simply stacked in array, collisions among neighboring components may occur during earthquakes or accidents. Thus, it is important to develop a reliable seismic model of the stacked graphite blocks and have them designed to maintain their structural integrity during the anticipated occurrences. Various aspects involved in modeling and calculating impact-contact dynamics can affect the resulting behavior of the graphite block. These include mesh size, time step, contact behavior, mechanical constraint formulation of impact-contact analysis, etc. This work is dedicated to perform comparative studies and the effects of these parameters will be identified. The insights obtained through these studies will help build a realistic impact-contact model of the graphite block from which a lumped or reduced dynamics model will be developed for the seismic analysis of the reactor including these graphite components.