Diabetes is a life-long chronic disease that affects more than 24 million Americans. Loss of pancreatic beta-cell mass and function is central to the development of both type 1 (T1D) and type 2 diabetes (T2D). Therefore, preservation or regeneration of functional beta-cell mass is one of the essential strategies to treat diabetes [1]. In my study, I tested if ranolazine, a synthetic compound, has potential to prevent or treat diabetes. Diabetes were induced in mice by giving multiple low-doses of streptozotocin (STZ). Ranolazine was given twice daily via an oral gavage (20 mg/kg) for 5 weeks. blood levels of glucose, insulin, and glycosylated hemoglobin (HbA1c) were measured. Glucose tolerance test was performed in control and treated mice. pancreatic tissues were stained with hematoxylin and eosin or stained with insulin antibody for islet mass evaluation. INS1-832/13 cells and human islets were further used to evaluate the effect of ranalozine on beta-cell survival and related signaling pathway. Fasting blood glucose levels after the fourth week of STZ injections were lower in ranolazine treated group (199.1 mg/dl) compared to the vehicle group (252.1 mg/dl) (p<0.01). HbA1c levels were reduced by ranolozine treatment (5.33%) as compared to the control group (7.23%) (p<0.05%). Glucose tolerance was improved in ranolazine treated mice (p<0.05). Mice treated with ranolazine had higher beta-cell mass (0.25%) than the vehicle group (0.07%)(p<0.01). In addition, ranolazine improved survival of human islets exposed to high levels of glucose and palmitate, whereas cell proliferation was not altered. In addition, ranolazine slightly increased the cAMP in MIN-6 cell and human islets. In conclusion, ranolazine may have therapeutic potential for diabetes by preserving beta-cell mass. / Master of Science

As the prevalence of Parkinson’s disease is expected to increase gradually over the years based on recent scientific predictions, developing a treatment plan to mitigate the development of this disease is essential. Previous research tried to tackle the motor and non-motor symptoms associated with the disease. That said, some symptoms seem to persist, and the quality of life of PD patients continues to decline. Zebrafish have emerged as a strong model to study the regeneration of DAergic neurons as they have the ability to show robust adult neurogenesis. Here, we used adult zebrafish to investigate DAergic neuron regeneration following ablation in various brain regions. In addition, we tested the efficacy of Nifurpirinol, an alternative substrate to MTZ, in ablating DAergic neurons in the adult zebrafish brain. Lastly, we tracked how the ablation of DAergic neurons influences the motor activity of adult zebrafish and how they tend to recover over time. Results showed a significant reduction in DAergic neurons at 7 days following the MTZ treatment in the olfactory bulb, telencephalon, and the periventricular pretectal nucleus. NFP also caused similar changes, albeit they were less statistically significant. In response to ablated DAergic neurons, MTZ-treated fish showed a significant increase in the number of neural stem cells undergoing proliferation at 1 dpt. However, the highest spike in proliferative cells, especially neural stem cells, was found at 7 dpt. This time point corresponded with the greatest decrease in DAergic neurons following ablation. These cellular changes were observed in the olfactory bulb and the telencephalon. That said, more drastic changes were noticed in the rostral and medial telencephalon. Results also showed that the adult zebrafish brain was not able to significantly replenish the number of DAergic neurons as early as 15 dpt. Based on previous observations, it seems that adult zebrafish need at least 45 days to regenerate their DAergic neurons to levels comparable to the DMSO control. Lastly, behaviour analysis showed that NFP has the most significant impact on motor activity across three different parameters at 0 hpt. MTZ also had similar effects on motor activity; however, it was less pronounced. The impact on the behaviour level seems more transient as some recovery was observed at 7 dpt. Overall, this transgenic zebrafish line allowed us to explore how and when the adult zebrafish brain was able to efficiently recover following the specific ablation of DAergic neurons. In addition, it expanded our understanding of adult neurogenesis which will hopefully allow us to better approach patients with Parkinson’s disease.

Serotonin has been widely explored in the brain. Recently, there have been new findings on how serotonin works in the periphery. Serotonin is introduced to the periphery by the enterochromaffin cells and metabolized by the liver and lung. Studies have shown that serotonin plays a role in controlling lung cancer. However, the mechanism by which it initiates tumor formation has not been fully explored. Cell viability was measured in several lung adenocarcinoma cell lines treated with serotonin to study this effect. In GFP-labelled cells, fluorescence intensity was measured for quantification of cell viability. Our data showed an overall increase in viability when serotonin concentration was increased, which is significant because it shows that serotonin affects lung cancer progression. We will look at how serotonin works on tumor cells compared to endothelial cells and its effect on immune system activation. This study hopes to inspire future anti-angiogenesis and immunotherapy studies of lung cancer by understanding this interaction.

In the process of exploring the thorium fuel application in CANDU reactors, it is important to consider the proliferation resistance level as a parameter for comparison with current natural uranium fuel. The concept of a whole fuel cycle was introduced to show the variations in the proliferation resistance level as the material is flowing through the cycle. The depletion and decay histories were simulated with SCALE 6.1 code and the results such as isotopes composition, decay heat, and radioactivity were used to analyze the material attractiveness of pure heavy metal for weapon production. They also served as the intrinsic features during the proliferation resistance level calculation. The Multi-Attribute Utility Analysis (MAUA) method developed by Chalton was used to compare different CANDU fuel cycles with quantified values (PR) from the viewpoint of proliferation resistance. To improve the biased MAUA results that gave a PR of 0.76 to CANDU while 0.93 to PWR, the attributes of size/weight and refueling scheme were reconsidered. In addition, the sensitive technology involved was added for the proliferation resistance recalculation. The results showed an increased PR value of 0.82 for natural uranium CANDU reactor as well as a decreasing trend of PR at the back end. PWR has a PR of 0.82 with revised MAUA method. The PR comparison of thorium and natural uranium fuel indicated that Th/Pu fuel has a slightly higher PR value in the reactor. The Figure of Merit (FOM) method developed by Bathke was used to validate the PR results from another perspective: the attractiveness of pure heavy metals that are suitable for nuclear weapon production. The results showed that FOM of plutonium keeps increasing with decay time and the trend becomes more significant after disposal in the deep geological repository. The FOM of uranium from Th/Pu cases is higher than that of Pu within several hundred years but maintains a decreasing trend. The decreasing FOM of uranium is preferred for direct disposal in deep geological repository. The decreased PR level and the increased FOM value of plutonium at the back end of a fuel cycle indicate the importance of implementing the security and safeguard for each facility dealing with nuclear materials. The comparison results of PR and FOM values for different fuel provided feedback and suggestions for the new fuel application. / Thesis / Master of Applied Science (MASc)

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Three studies were conducted to achieve the following respective objectives: 1) to determine the cellular mechanism by which growth hormone (GH) stimulates skeletal muscle growth; 2) to identify the signaling pathways that mediate the different effects of insulin-like growth factor I (IGF-I) on skeletal muscle growth; and 3) to determine the role of a functionally unknown gene named SH3 and cysteine rich domain 3 (STAC3) in myogenesis. In the first study, the myogenic precursor cells, satellite cells, were isolated from cattle and allowed to proliferate as myoblasts or induced to fuse into myotubes in culture. GH increased protein synthesis without affecting protein degradation in myotubes; GH had no effect on proliferation of myoblasts; GH had no effect on IGF-I mRNA expression in either myoblasts or myotubes. These data suggest that GH stimulates skeletal muscle growth in cattle in part through stimulation of protein synthesis and that this stimulation is not mediated through increased IGF-I mRNA expression in the muscle. In the second study, the signaling pathways mediating the effects of IGF-I on proliferation of bovine myoblasts and protein synthesis and degradation in bovine myotubes were identified by adding to the culture medium rapamycin, LY294002, and PD98059, which are specific inhibitors of the signaling molecules mTOR, AKT, and ERK, respectively. The effectiveness of these inhibitors was confirmed by Western blotting. Proliferation of bovine myoblasts was stimulated by IGF-I, and this stimulation was partially blocked by PD98059 and completely blocked by rapamycin or LY294002. Protein degradation in myotubes was inhibited by IGF-I and this inhibition was completely relieved by LY294002, but not by rapamycin or PD98059. Protein synthesis in myotubes was increased by IGF-I, and this increase was completely blocked by rapamycin, LY294002, or PD98059. These data demonstrate that IGF-I stimulates proliferation of bovine myoblasts and protein synthesis in bovine myotubes through both the PI3K/AKT and the MAPK signaling pathways and that IGF-I inhibits protein degradation in bovine myotubes through the PI3K/AKT pathway only. In the third study, the potential roles of STAC3 in myoblast proliferation, differentiation, and fusion were investigated. Overexpression of STAC3 inhibited differentiation of C2C12 cells (a murine myoblast cell line) and fusion of these cells into myotubes, whereas knockdown of STAC3 had the opposite effects. Either STAC3 overexpression or STAC3 knockdown had no effect on proliferation of C2C12 cells. Myoblasts from STAC3-deficient mouse embryos had a greater ability to fuse into myotubes than control myoblasts; the former cells also expressed more mRNAs for the myogenic regulators MyoD and myogenin and the adult myosin heavy chain protein MyHC1 than the latter. These results suggest that STAC3 inhibits myoblast differentiation and fusion. / Ph. D.

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