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Skeletal muscle satellite cells (SC) are essential in muscle repair and regeneration. The role of SCs in mediating hypertrophic adaptations following resistance training has been widely studied. Recent evidence from endurance training studies suggest that SCs may also play a role in mediating non-hypertrophic adaptations. Indeed, it has been shown that satellite cells respond to endurance training. Work in rodent models suggest that exercise intensity may play an important role in expanding the SC pool whereas the results of endurance training studies in humans are much less consistent. Limited evidence also suggest that exercise intensity may be important in mediating exercised-induced capillarization following endurance training in humans. In both instances, it is unknown whether the on-and-off pattern characteristic of interval training (i.e. the rest-work cycles) plays a role in the magnitude of these skeletal muscle responses to this type of exercise. Thus, we sought to determine if the rest-to-work cycle plays a role in the scope of these skeletal muscle responses by comparing the SC response and capillarization to two distinct work-matched protocols that are performed at the same intensity but at two different exercise patterns (interval versus continuous). We hypothesized that interval exercise will elicit a greater SC response and induce greater capillary growth compared to work-matched continuous exercise. Ten young active individuals performed 12 sessions of counterweighted single-leg cycling over 4 weeks. Each leg was randomly assigned to Interval (INT) (10 x 3-min intervals at 50% of single leg peak power output (PPO), with 1 min recovery) or Continuous (CONTIN) (30 min at 50% PPO, followed by 10 min recovery), which were performed 5 min apart on each day, in an alternating order. Resting muscle biopsies were obtained from the vastus lateralis pre- and post-training. Immunofluorescent microscopy of muscle cross sections was used to assess muscle fibre capillarization, SC expansion and activation. Western blot analysis was performed on pro-angiogenic factors, specifically VEGF and VEGFR2. Mixed muscle SC activation increased in the INT leg compared to the pre-training time-point (3.2 ± 0.5 vs. 1.5 ± 0.2 Pax7+/MyoD+ cells/ 100 myofibers, respectively; P < 0.05). Mixed muscle SC activation did not increase significantly in the CONTIN leg compared to the pre-training time-point and there was no significant difference in activation between CONTIN and INT post-training. With regards to capillarization, no differences in type I or type II muscle fibre CC (capillary contacts), C/Fi (individual capillary-to-fibre ratio) or CFPE (capillary-to-fibre perimeter exchange index) were observed post-training or between legs. No significant expansion of the SC pool occurred in either legs post-training and no increases in fibre cross-sectional area was observed. This study presents novel evidence of mixed muscle SC activation following interval exercise training that is not observed following work- and intensity-matched continuous exercise training. This suggest that the rest-to-work cycle associated with interval exercise may dictate, to some extent, SC activation whereas it may not be a primary stimulus for training-induced changes in capillarization. / Thesis / Master of Science (MSc)

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We investigate the relative equilibria of a gyrostat with a spring-mass-dashpot damper to gain new insights into the dynamics of spin-stabilized satellites. The equations of motion are developed using a Newton-Euler approach, resulting in equations in terms of system momenta and damper variables. Linear and nonlinear stability methods produce stability conditions for simple spins about the nominal principal axes. We use analytical and numerical methods to explore system equilibria, including the bifurcations that occur for varying system parameters for varying rotor momentum and damper parameters. The equations and bifurcations for zero rotor absolute angular momentum are identical to those for a rigid body with an identical damper. For the more general case of non-zero rotor momentum, the bifurcations are complex structures that are perturbations of the zero rotor momentum case. We examine the effects of spring stiffness, damper position, and inertia properties on the global equilibria. Stable equilibria exist for many different spin axes, including some that do not lie in the nominally principal planes. Some bifurcations identify regions where a jump phenomenon is possible. We use Liapunov-Schmidt reduction to determine an analytic relationship between parameters to determine if the jump phenomenon occurs. Bifurcations of the nominal gyrostat spin are characterized in parameter space using two-parameter continuation and the Liapunov-Schmidt reduction technique. We quantify the effects of rotor or damper alignment errors by adding small displacements to the alignment vectors, resulting in perturbations of the bifurcations for the standard model. We apply the global bifurcation results to several practical applications. We relate the general set of all possible equilibria to specific equilibria for dual-spin satellites with typical parameters. For systems with tuned dampers, where the natural frequency of the spring-mass-damper matches the gyrostat precession frequency, we show numerically and analytically that the existence of certain equilibria are related to the damper tuning condition. Finally, the global equilibria and bifurcations for varying rotor momentum provide a unique perspective on the dynamics of simple rotor spin-up maneuvers. / Ph. D.

In the equine industry, there is a need for supplements that can improve performance and muscle recovery. Tributyrin and butyrate affect satellite cells and oxidative metabolism in other species. To assess the effects of tributyrin on equine muscle repair, Thoroughbred horses were supplemented tributyrin, and a submaximal exercise test was performed. RNA isolated from the gluteal muscle of horses supplemented with tributyrin had increased myogenin mRNA. Satellite cells isolated from supplemented horses had a higher percentage of proliferating cell nuclear antigen immunopositive cells, indicating tributyrin primed satellite cells to activate. Another experiment was performed to test the effects of tributyrin supplementation on equine muscle metabolism. Horses were fed tributyrin for 30 days while partaking in light exercise training. After the supplementation period, horses performed an exhaustive exercise test. Tributyrin supplementation did not affect performance or measures of oxidative metabolism in the muscle. To measure the effects of butyrate on equine muscle metabolism, Thoroughbred horses were supplemented butyrate for 30 days. At the end of supplementation gluteal muscle from butyrate fed horses had a higher percentage of type IIA fibers. Tributyrin supplementation demonstrated positive effects on satellite cell activation, but failed to increase oxidative metabolism measures. Butyrate did statistically increase the percentage of type IIA fibers, but not oxidative enzyme activity and the modest increase seen would likely not effect performance. Higher doses and longer supplementation of butyrate and tributyrin should be investigated to see if a metabolic shift beneficial to racehorses can be achieved. Furthermore, future research should focus on tributyrin's effects on satellite cells and how supplementation can improve muscle recovery in racehorses. / Doctor of Philosophy / Thoroughbred racehorses take part in strenuous races that result in exercise induced damage to the muscle. In turn, this resulting damage to the muscle must be properly repaired before the horse can successfully race again. My projects involved finding nutritional supplements to improve equine muscle repair or metabolism. A special cell in the muscle, called a satellite cell is responsible for repairing this muscle damage. Unlike other muscle nuclei, satellite cells have the ability to divide, providing more myonuclei, able to fuse into muscle fibers for repair. In an un-damaged state, satellite cells are lying dormant in the muscle. However, upon stimulus, satellite cells leave their dormant state and become activated. Along with muscle damage, a lot of energy is used during a race. There are two main ways that energy can be made, either without oxygen (anerobic) or with oxygen (aerobic). Aerobic metabolism is able to produce more energy and is fatigue resistant. I supplemented Thoroughbred horse's diet's with two products, butyrate or tributyrin to test their effects on equine satellite cells and muscle metabolism. Ultimately, my research found that tributyrin was able to stimulate equine satellite cells activate after exercise. I also found that butyrate supplementation increased the percentage of aerobic muscle fibers.

The Iridium satellite system as proposed by Motorola, Inc. provides continuous global communications coverage by supplementing prevailing telephone services. The satellite system is comprised of 66 Low Earth Orbiting (LEO) satellites which are able to accommodate Iridium handsets or existing telephone links. These satellites are monitored and controlled by ground control facilities for approximately 6 years ( the estimated life of the vehicles) and are then replaced. The ground control facilities are required to provide software upgrades, monitor the health of the vehicles, remove a satellite from the constellation when necessary, and coordinate launch and deorbit of the satellites. The approach used to code and modulate the telemetry processed by the ground stations is analyzed in order to develop support software for a recommended data network configuration used at the ground stations. A Reed-Solomon coding scheme is prepared for the telemetry channel since this coding scheme corrects bit errors and protects against burst errors. The Groupe Speciale Mobile (GSM), a combination of time division mUltiple access, TDMA, and frequency division multiple access, FDMA, is recommended for use by Iridium. A bus topology with a fiber backbone is suggested to support the operations at each facility and a separate landline is considered to support operations between the facilities when possible. The support software is available in the appendix and is written in Fortran 77. A data security coding algorithm is introduced; however, this is not a requirement or a concern for Motorola and is an option that may be considered by the ground facilities. The data security for a commercial satellite system is considered insignificant at this time. / Master of Science

Intrauterine growth restriction causes impaired growth and development of mammalian fetus, and leads to long-term negative effect on postnatal growth. Among domestic animals, pigs exhibit the most severe naturally occurring IUGR and reduced postnatal muscle growth. The objectives of this research project were to: 1) determine muscle stem cell characteristics in IUGR pigs; 2) determine how intrauterine growth restriction alters protein deposition in skeletal muscle; 3) investigate whether branched-chain amino acids (BCAA) are able to enhance protein synthesis in intrauterine growth restricted (IUGR) pig muscle. Newborn piglets were considered normal body weight (NBWT) or IUGR when birth weight was within ± 0.5 SD and -2 SD of litter average respectively. Muscle satellite cell numbers, believed to be the major nuclei source for postnatal muscle growth, were lower in newborn IUGR pigs which could result in reduced muscle hypertrophy potential. In addition, cultures derived from IUGR muscle satellite cells had a lower fusion percentage. Fewer satellite cells and impaired differentiation ability may contributor to impaired muscle growth in these pigs. Protein synthesis rate was significantly lower in IUGR pig hindquarter in the first hour after feeding, but BCAA supplementation had no effect on protein synthesis in IUGR pigs. Further, eukaryotic translation initiation factor 4E (eIF4E) expression is down regulated in IUGR pig muscle. These results suggest that impaired translation initiation may provide a plausible explanation for the lower protein synthesis rates observed in IUGR pigs. Overall, reduced muscle stem cell number and changes in their activity, as well as impaired translation initiation may be important explanations for compromised postnatal muscle growth in intrauterine growth restricted pigs. / Ph. D.

Satellite glial cells (SGC) are laminar cells that wrap completely around the sensory neuron and are responsible for buffering extracellular K+ after neuronal excitation. A decrease in the potassium buffering capacity of SGC has been associated with neuropathic pain (NP) behavior and apoptosis. This dissertation investigated the role of the potassium buffering capacity and apoptosis of trigeminal satellite glial cells (SGC) in the maintenance and development of orofacial NP in rats using in vivo and in vitro methodologies. In vivo endpoints were evaluated after performing chronic constriction injury (CCI) of the infraorbital nerve (IoN). NP signs and behavior were evaluated at 5, 10, 20 40 and 80 hours after injury. We evaluated the potassium buffering capacity of SGC by measuring the intracellular potassium concentration and protein levels and gene expression of the Kir4.1 and the SK3 potassium channels and gap junction protein connexin 43 (Cx43). We evaluated apoptosis endpoints including protein levels and gene expression of apoptotic related proteins bcl-2, caspase 9, caspase 3 and p53. Results indicate that NP signs developed as early as 5 hours after injury. After PNI, SGC responded by increasing their intracellular potassium concentration and by increasing protein levels of Kir4.1, SK3 and Cx43. Nonetheless, this increase in protein levels was not accompanied by an increase in gene expression. Apoptosis results revealed that SGC decreased protein levels and gene expression of anti-apoptotic protein Bcl-2. Using in vitro methodologies, we developed primary trigeminal SGC cultures and evaluated how a decrease in the intracellular potassium concentration modulates apoptosis induced by the mitochondrial and death receptor pathways. SGC depleted of potassium after hypoosmotic shock showed a significant increase in early apoptosis after incubation with mitochondrial pathway apoptotic inducer staurosporine when compared to SGC with normal intracellular concentration. This research has revealed that SGC respond early to PNI by increasing their potassium buffering capacity. We also determined that the mitochondrial apoptotic pathway might be involved in the trigeminal SGC response to PNI. From our in vitro experiments we have revealed that potassium is an important modulator of apoptosis induced by the mitochondrial pathway in cultured trigeminal SGC. / Ph. D.

Many industries are turning to wireless communication systems to track their assets. One example of such an industry is the shipping industry, where — under the growing emphasis on homeland security — tracking cargo containers and their contents has become a high priority. There are several beacons on the commercial market that will meet this need if the required beacon does not need to be independently powered or to have global coverage. This thesis attempts to find a design solution for a beacon that transmits location data, is battery powered, and has world-wide coverage. The beacon is intended to be a low power, transmit only device, and the receiver will not be designed to operate in real-time. Several communication systems were evaluated on these conditions, and the Globalstar Satellite System was selected to use as the communication system for the beacon. The Globalstar Satellite System is a low earth orbiting (LEO) satellite system and uses Code Division Multiple Access (CDMA) to allocate system resources to the maximum number of users possible. Discussions of spread spectrum techniques and theory, Rake receivers, and error correction codes are included as a background for the design. This thesis examines the initial steps in the design of the transmitter beacon and aims to determine the minimum required beacon transmit power for good receiver performance. A portion of the correlator in the Globalstar receiver is simulated for several scenarios: a single user case with varying transmit power, and a multiple user case with fixed transmit power. Although not likely to occur, the single user case was used to baseline system performance and to verify the multi-user case results. The simulated correlator employed a parallel search strategy and used a truncated version of the Globalstar system code sequence. Finally, a threshold analysis was performed to determine if better receiver performance could be obtained. / Master of Science