No description available.

No description available.

No description available.

No description available.

No description available.

Spinal cord injury results in life-long damage to sensory and motor functions. Recovery from these injuries is limited and often insufficient because the lack of stimulation from supraspinal systems results in further atrophy of the damaged neural pathways. Current studies have shown that repeated sensory activity obtained by applying stimulation enhances plasticity of neural circuits, and in turn increases the ability to create new pathways able to compensate for the damaged neurons. Functional electrical stimulation has been proven to show success in this form of rehabilitation, but it has its limitations. Stimulating neural pathways with electricity results in also stimulating surrounding neurons and muscle tissue. This results in attenuation of the intended effect. The use of optogenetics mitigates this issue, but comes with its own complications. Optogenetics is a growing method of neural stimulation which utilizes genetic modification to create light activated ion channels in neurons to allow for activation or suppression of neural pathways. In order to activate the neurons, light of the appropriate wavelength must be able to penetrate the nerves. Applying the light transcutaneously is insufficient, as the skin and muscle tissue attenuate the signal. The target nerve may also move relative to an external point on the body, creating further inconsistency. Specifically in the case of using a rat model, an external object will be immediately removed by the animal. This thesis seeks to address this issue for a rat model by designing a nerve cuff capable of both optical and electrical stimulation. This device will be scaled to fit the sciatic nerve of a rat and allow for both optical activation and inhibition of the neural activity. It will be wired such that each stimulus may be operated individually or in conjunction with each other. The simultaneous stimulation is required in order to validate the neural inhibition facet. The circuit itself will be validated through the use of an optical stimulation rig, using a photoreceptor in place of an EMG. The application of the cuff will be verified in a live naive rat. Aim 1: Design and build an implantable electrical stimulation nerve cuff for the sciatic nerve of rats. An electrical nerve cuff for the sciatic nerve of a rat will be designed and assembled such that it is able to reliably activate the H-reflex. For it to be used in a walking rat, the cuff must be compatible with a head mount in order to prevent the rat from being able to chew at the wiring or their exit point. The cuff will be controlled through a Matlab program that is able to output specified signals and compare these outputs directly with the resultant EMG inputs. Aim 2: Implement LEDs onto the cuff and perform validation experiments. Light delivery capability will be added to the cuff through the use of LEDs. The functionality of the cuff will be validated through tests on naive rats. If successful, only an electric stimulation will result in a muscle twitch. An optical stimulation should result in no twitches, which would then validate that no current is leaking from the nerve cuff, given that the rat does not express any light sensitive protein channels. Ultimately, with a rat expressing ChR2 opsins on the sciatic nerve, an activation of the nerve using a blue light of wavelength 470nm will result in activating an h-wave without an m-wave when optically stimulated. Similarly, using the nerve cuff with a rat expressing ArchT opsins will result in suppressing the h-wave from an electric stimulation once the sciatic nerve is illuminated with green light of a wavelength of 520 nm. / Bioengineering

No description available.

Flexor tendon lacerations in horses are traumatic injuries that can be career ending and life threatening. In the horse, a tendon repair must withstand the strains placed on the tenorrhaphy by immediate weight bearing and locomotion post-operatively. Despite the use of external coaptation, such strains can lead to significant gap formation, construct failure, longer healing time and poor quality of the healed tendon. Similar to equine surgery, gap formation and construct failure are common concerns in human medicine, with early return to post-operative physiotherapy challenging the primary repair. Early return to exercise and decreased gap formation has been shown to reduce adhesion formation. Based on these concerns, the ideal tenorrhaphy suture pattern for equines would provide: 1) high ultimate failure load, 2) resistance to gap formation, 3) minimal alteration in blood supply, and 4) minimal adhesion formation. Historically, various suture patterns and materials have been evaluated for human and equine flexor tendon repair. Results of equine studies suggest the three-loop pulley pattern (3LP) compares favorably to other patterns and is recommended for primary tenorrhaphy. However, this pattern still experiences significant gap formation and can result in failure. As a result, a technique which decreases the problems inherent in the 3LP is warranted for tenorrhaphy of equine flexor tendons. A review of the human literature highlights certain characteristics of the tenorrhaphy that may improve results including core purchase length and suture loop characteristics. Optimization of these tenorrhaphy characteristics can increase tenorrhaphy performance and patient outcome. The six-strand Savage technique (SSS) is a pattern routinely used in human hand surgery for tendon repair, and possesses high ultimate failure load and resistance to gap formation that may be beneficial for application in equine tendon repair. This study compared a novel tenorrhaphy pattern for horses, the SSS, with the currently recommended pattern, the 3LP, in an in vitro model. We hypothesize the SSS will fail at a higher ultimate load, resist pull through, and resist gap formation better than the 3LP. All testing used cadaveric equine superficial digital flexor tendons from horses euthanized for reasons other than musculoskeletal injury. All testing was approved by the IACUC. The two techniques were applied to cadaveric equine superficial digital flexor tendons. The same investigator performed all repairs (EE). Biomechanical properties were determined in a blinded, randomized pair design. Ultimate failure load, mode of failure and load required to form a 3mm gap were recorded on an Instron Electropuls materials testing system. Gap formation was determined using synchronized high-speed video analysis. Results are reported as mean + standard deviation. Statistical comparisons were made using Student's T test, with significance set at p<0.05. The tenorrhaphies were tested for their ultimate failure load and failure mode. The mean failure load for the SSS construct (421.1 ± 47.6) was significantly greater than that for the 3LP repaired tendons (193.7 ± 43.0). Failure mode was suture breakage for the SSS constructs (13/13) and suture pull through for the 3LP constructs (13/13). The maximum load to create a 3mm gap in the SSS repair (102.0N ± 22.4) was not significantly different from the 3LP repair (109.9N ± 16.0). The results of the current study demonstrate that the SSS tenorrhaphy has a higher ultimate failure load and resistance to pull through than the 3LP. The biomechanical properties of the SSS technique show promise as a more desirable repair for equine flexor tendons. However, in vivo testing of the effects of the pattern on live tissue and in a cyclic loading environment is necessary before clinical application of the pattern is recommended. / Master of Science

Over 2.4 million eye injuries occur each year in the United States as a result of trauma. Eye injuries have been investigated for years; however, the role of the extraocular muscles in relation to eye injuries has yet to be quantified. In this research, Computed Tomography quasi-static tests were conducted to investigate the effect of the presence of the extraocular muscles on the biomechanical response of the human eye in situ. Three matched pairs of human eyes were displaced in 5 mm increments using a large flat cylindrical indenter to a maximum displacement of 30 mm. The loading was similar to what is experienced during a blunt impact, which is believed to cause the most serious eye injuries. In the matched pair, one eye had the extraocular muscles intact and the other had the extraocular muscles transected. Force, pressure, and displacement measurements were collected for each test. A trend was seen where a greater amount of force was created in the eye with the extraocular muscles intact than in the eye with the muscles transected, and a correlation between them was made. The greatest force measured in an eye with the extraocular muscles intact was 92 N, while the greatest force measured in an eye with the extraocular muscles transected was 80 N. An increase in intraocular pressure was also noticed for an eye with the extraocular muscles attached, rising steadily from 2 kPa to a maximum pressure of just over 50 kPa. It was also noted that during a quasi-static impact the eye can move out of the way of the imposing force. Since the test data set was small, analytical calculations were also conducted. / Master of Science

The use of digital technology is becoming increasingly popular in equine research. Current applied technologies for livestock are being used to detect pathogens, observe locomotion patterns, determine estrus periods, and measure vital parameters. These sensors leverage global positioning systems, accelerometers, magnetometers, goniometers, optics, among other emerging sensing technologies. The success of these devices has led to the introduction of various equine wearable sensors into market. These technologies seek to promote mobile devices to be used in equine training, monitoring, and clinical contexts. Therefore, the objective of this research is to characterize advancements, opportunities, and gaps in our existing knowledge of equine wearable sensor technology. Specifically, this research explores two innovative sensors designed for equines and their potential to enhance animal safety and health. The purpose of the research on these sensors is to (1) better contextualize biomechanical data in practically applicable terms and (2) evaluate the accuracy of a photoplethysmography based pulse sensor to detect heart rates of adult horses. In addition, currently marketed equine wearable sensors are reviewed, and their limitations are evaluated. Areas of future research and developments of equine wearable technologies are also explored. / Master of Science / The use of digital technology is becoming increasingly popular in equine research. Several biosensors exist for livestock species which have been successful in helping manage health and wellbeing of these animals. Although commercial development of equine wearable sensors has begun, the success of initial industry prototypes is limited. Commercially available equine wearable sensors currently marketed often seek to provide support in equine training, monitoring, and clinical contexts. Despite several commercially available equine wearable sensors, there has been slow adoption of this type of technology in the industry. Therefore, the objective of this research is to characterize advancements, opportunities, and gaps in our existing knowledge of equine wearable sensor technology. Specifically, it explores two innovative sensors designed for equines and their potential to improve the safety and health these animals. The purpose of these sensors are to (1) better understand factors that influence the safety of equestrian sports with jumping phases and (2) evaluate the accuracy of a sensor to detect heart rates of adult horses. In addition, current marketed equine wearable sensors are reviewed, and their limitations are evaluated. Areas of future research and developments of equine wearable technologies are also explored.