VictorJuiz/thesis huggingface dataset:
The Temporal Integration of Memory

Episodic memory is defined by the temporal ordering of events, yet, how events occurring close together in time become integrated remains unclear. Evidence from previous studies indicate that increased excitability biases neuronal allocation to a memory trace and that following a learning event, the excitability of allocated neurons remains enhanced for 6 hours. This period of increased excitability provides a window during which additional experiences can become co- allocated to same population. This population overlap has previously been demonstrated to underlie memory integration between two fearful events (Rashid et al., 2016). Here, we demonstrate that an unrelated stimulus can also become integrated into a recently formed fearful memory if animals are exposed to the stimulus within the 6-hour window, effectively forming a false memory where animals display fear to a previously neutral stimulus. These effects were then reversed using optogenetics, suggesting that integration is critically dependent on neuronal excitability.

Advisor: Josselyn, Sheena
Salmon Lice (Lepeoptheirus salmonis) Increase Age-at-maturity in Atlantic Salmon (Salmo salar) by Decreasing Growth: An Estimate of Parasite Effects on Host Growth

The decline in wild Atlantic salmon stocks throughout the North Atlantic has been linked to the complex interactions between these fish in all life stages of their life and numerous anthropogenic activities. One noteworthy interaction is between salmon lice and Atlantic salmon, as some of the declines have been linked back to increases in parasite abundance. However, it is unclear how salmon lice can impact changes in the life-history traits of Atlantic salmon. Here, I use data from a long-term field study to show that salmon lice decrease the growth rate of wild fish, causing them to mature at an older age and size. I also build a size-structured population model and use it to quantify the difference in growth rate between a group of fish treated and untreated for salmon lice. My findings are consistent with predictions of life-history theory, that hosts can alter life-history traits in response to parasitism. Considering the indirect effects of parasitism on critical life-history traits will give better insight into the resilience of wild populations and help improve management strategies.

Keywords: Atlantic salmon
Conservation
Disease
Life-history traits
Parasites
Salmon lice
Advisor: Krkosek, Martin
Working Memory in Oral Contraceptive Users: Does Time of Pill Ingestion and the Catechol-o-methyltransferase Val158Met Single Nucleotide Polymorphism Influence Working Memory?

The main estrogen produced by the ovaries, 17-beta estradiol (E2), interacts with different DA availabilities due to the COMT Val158Met polymorphism to modulate WM. Whether the commonly used synthetic estrogen, ethinyl estradiol (EE), does the same is unknown. To addressed this question, we investigated WM in OC users. Additionally, we examined if the pharmacokinetics of EE affect WM by testing OC users at a peak EE state 1-2 hours after pill ingestion, and at a low EE state just before pill ingestion. Naturally cycling controls were tested at low and high E2 menstrual cycle phases. Our preliminary results indicate time since pill ingestion does not affect WM performance, but COMT genotype may differentially affect WM in NC and OC women. These data suggest that despite the pharmacokinetics of EE in OC users and the variability of DA breakdown, women on OCs have stable WM throughout the day.

Keywords: Catechol-o-Methyltransferase
Dopamine
Estrogen
Oral Contraceptives
Pharmacokinetics
Working Memory
Advisor: Einstein, Gillian
Developing Receptor-directed Synthetic Antagonists against the IL-23 Signal Transduction Pathway

IL-23 is a pro-inflammatory cytokine that initiates and stabilizes the TH17 lineage of T helper cells, often associated with autoimmune inflammatory conditions such as inflammatory bowel disease (IBD), psoriasis, and arthritis. Several antibodies targeting IL-23 have been developed but only one monoclonal antibody has been developed to target IL-23 signaling at the level of the receptor. Using in vitro selections against recombinant IL-23R, we have isolated one antibody from a phage-displayed synthetic antibody library which bound the receptor with high affinity, and interacts with ectopically-expressed cell surface receptors. This antibody was also shown to block the in vitro ligand-receptor interaction and antagonize IL-23-induced STAT3 signalling in cells. These results represent the first report of a recombinant antibody against IL-23R that antagonizes downstream cytokine-induced signalling. Further development and characterization of such antibodies would be beneficial since antibodies that block IL-23 signals at the level of the receptor may possess therapeutic value.

Advisor: Sidhu, Sachdev
Development of Carbon Tolerant Anodes for Solid Oxide Fuel Cells Fabricated by Solution Precursor Plasma Spraying

Carbon black (CB) pore former was incorporated into the solution precursor plasma spraying (SPPS) fabrication of Ni-YSZ anodes. Increasing the amount of feedstock CB content led to anodes with higher open porosity, to the detriment of deposition efficiency. Introducing CB to the SPPS of Ni-YSZ did not affect the composition of the deposited coatings. Due to the limited data set from electrochemical tests, no definitive relationship between the feedstock CB content and the polarization processes could be established. A Ni3Sn-YSZ anode was fabricated using an SPPS process. It was determined that the coating was marginally tin rich, yielding a minor Ni3Sn2 phase. A cell containing the Ni3Sn-YSZ anode was operated in dry CH4 at 750℃. The cell was held at a current density of 0.12 A/cm2 for 600 hours and demonstrated remarkable stability. No notable microstructural or compositional changes occurred during the test.

Keywords: anode
direct oxidation
ni3sn
plasma spray
SOFC
solid oxide fuel cell
Advisor: Kesler, Olivera
Innovation in Low Back Pain Care in Ontario – ISAEC Program Evaluation

This research investigated low back pain (LBP) management in the primary care setting and in the Inter-professional Spine Assessment and Education Clinics (ISAEC). We conducted a descriptive analysis to characterize the patient populations in the two settings. Further, we evaluated the impact of the ISAEC program on patients’ LBP progression using a pre- and post- analysis. Our analysis showed that on average, patients significantly improved on disability index, pain levels, quality of life, and psychological factors. Lastly, we investigated the medical services referrals, medication prescription and utilization patterns for patients in the two settings. Our analysis suggested high frequency of referrals to surgical consultations and diagnostic imaging by primary care physicians. Our analysis also showed that ISAEC patients decreased usage of pharmaceutical treatment 6 months after enrolling into the ISAEC program, while patients in the primary care setting continued to receive medications for the treatment and management of LBP.

Advisor: Carter, Michael W
Exploring Deprescribing Opportunities for Community Pharmacists

Background: Deprescribing, the process of stopping medications, can reduce the use of harmful or unnecessary medications, but is challenging for patients and prescribers to implement. We explored Ontario community pharmacists’ involvement with deprescribing and strategies for enhancing this involvement. Methods: We conducted qualitative telephone interviews with 17 Ontario community pharmacists. The Behavior Change Wheel informed the interviews and analysis. Four investigators coded three transcripts independently to develop a codebook. One investigator coded the remainder and generated themes using thematic analysis. Results: Pharmacists’ involvement in deprescribing was affected by: 1) their understanding of deprescribing, 2) their access to patient information, and 3) competing clinical and business/technical demands of their daily activities. Conclusions: Findings support recommendations for optimizing community pharmacists’ involvement in deprescribing by defining their deprescribing role with multi-stakeholder engagement, focusing on specific steps within deprescribing, and expanding pharmacists’ understanding of how to integrate deprescribing into their practices.

Keywords: Behaviour Change Wheel
Community Pharmacists
Deprescribing
Qualitative
Advisor: McCarthy, Lisa
MacKeigan, Linda
Development and Evaluation of a Simulator for Surgical Training in Tracheostomy and Advanced Open Airway Surgery

The challenges of resident work-hour restrictions, low case volumes and growing concerns over patient safety limit learning opportunities for surgical trainees in the operating room. Surgical simulation can provide trainees with valuable opportunities to develop technical skills without risk to patient safety. Current synthetic airway simulators lack realistic tissue characteristics and anatomical accuracy. The objective of this thesis was to develop and validate a realistic airway simulator for training in tracheostomy and laryngotracheoplasty using anterior costal cartilage and thyroid ala cartilage grafts. A late adolescent/adult airway simulator was developed using image segmentation techniques, three-dimensional modeling/printing, and silicone casting. Nine expert otolaryngologists-head and neck surgeons evaluated the synthetic simulator as realistic/anatomically accurate (face validity), comparable to a live porcine model (gold standard in open airway simulation) and having perceived effectiveness as a training tool (content validity). The synthetic airway simulator has the potential to enhance tracheostomy and open airway surgical education.

Keywords: laryngotracheoplasty
open airway surgery
otolaryngology
resident education
simulation
tracheostomy
Advisor: Harrison, Robert V
Effects of Anti-αIIb-mediated Fetal Neonatal Alloimmune Thrombocytopenia on Fetal Hematopoietic Stem Cells and Embryonic Development

Fetal neonatal alloimmune thrombocytopenia (FNAIT) is characterized by an aberrant maternal immune response against fetal platelet antigens that can result in severe bleeding and miscarriage. Platelet receptor αIIbβ3 integrin is commonly targeted however there are disproportionately fewer reports of FNAIT against the αIIb subunit despite an equal prevalence of polymorphisms in the population, possibly due to increased fetal death. αIIb is also expressed on hematopoietic stem cells (HSCs). Whether they are targeted by alloantibodies, or contribute to increased disease severity is unknown. Using murine models, I revealed fetal death is prevalent in anti-αIIb-mediated FNAIT and significantly more frequent than in anti-β3-mediated. I found significantly reduced αIIb+ and αIIb- HSC, and HSC progenitor populations in fetal liver, placenta and fetal blood in FNAIT, in addition to a 3-fold decrease in hepatic megakaryocyte populations. These findings may explain the dearth of anti-αIIb-mediated FNAIT cases and the mechanisms of increased disease severity.

Keywords: fetal neonatal alloimmune thrombocytopenia
hematopoietic stem cell
megakaryocytes
placenta
platelets
αIIbβ3 integrin
Advisor: Ni, Heyu
The Development of a Local Food Environment Policy Framework and its Application in Several Ontario Municipal Jurisdictions

Governments can influence diet quality through policies that improve the state of the food environment. While national and state/provincial obesity prevention efforts have been well documented, monitoring at the municipal level has not been widely explored. This thesis aimed to develop a framework and inventory to monitor municipal food environment policies and government action, and apply it in three municipal jurisdictions in Ontario, Canada. The collection of implemented policies within US and Canadian municipalities suggest that local governments have the authority and capacity to introduce novel policies in many food environment domains to promote healthy food choices. Currently, municipal governments in Ontario are using a variety of approaches to create healthy food environments, but local government and non-government experts agreed there are areas for further improvement. These findings will help municipalities identify the strengths and opportunities to address weaknesses in their food environments to improve population health.

Keywords: Canada
food environment
food policy framework
municipal governments
Ontario
US
Advisor: L'Abbé, Mary
Novel High-throughput Drug Screening Application Using Human Cardiomyocytes In Mechanically Controlled Environment

Drug side-effects endanger patients and cause drug recalls from the market. High-throughput screening (HTS) tests with human cardiomyocytes (CMs) can detect drug side-effects earlier in the drug development process, but no available HTS test assesses CM contraction amplitude. We established 96-well substrates with modulus corresponding to both, healthy and diseased heart tissue that ‘wrinkle’ upon cell force exertion. Stem cell-derived CMs were used to quantify frequency, amplitude, and regularity of contraction in response to substrate modulus, drugs with known effects on heart function, and electrical pacing. The wrinkling device was benchmarked against an industry-standard impedance assay. Wrinkling substrates tuned to the modulus of heart enhanced CM maturity, including sarcomere alignment (α-actinin staining), which correlated with higher degree of CM responsiveness to drug treatment. Thus, the wrinkling assay fills the gap of HTS tests for the measure of CM contraction amplitude and enhances the sensitivity of in vitro drug tests.

Keywords: cardiomyocytes
drug screening
high-throughput
iPSC-CM maturation
mechanical stiffness
silicone polymer
Advisor: Hinz, Boris
Involvement of Lipids in the Physicochemical and In Vitro Characteristics of Polymer-lipid Nanoparticles in Cancer Cell Models

Polymer-lipid nanoparticles (PLN) have been a focus in cancer chemotherapy research due to their potential for targeting tumour cells, overcoming drug resistance and reducing toxicity. This work explores the (1) impact of “lipid” component properties and formulation parameters on PLN physicochemical properties and in vitro cytotoxicity using statistical design-of-experiments, and (2) mechanisms of PLN cell entry and organelle distribution, and response to lysosomal environments. These analyses show effects of melting point and chemical structure of multiple fatty acids/esters, and long heat exposure on PLN properties. As a result, a robust PLN system was optimized as a doxorubicin (DOX) delivery system for human glioblastoma U87-MG-RED-FLuc cells. This PLN system demonstrated intracellular internalization by multiple cell mechanisms. Furthermore, mechanistic studies examined the role of not only the optimized PLN in glioblastoma cells, but also in a previously-studied myristic acid-based PLN in breast tumour cells on improved potency over free drug.

Keywords: breast cancer
ethyl arachidate
factorial design
fatty acid binding protein
glioblastoma
polymer lipid nanoparticle
Advisor: Wu, Xiao Yu
Design and Study of Novel Fluorinated Tags for Elucidation of Protein Conformational Dynamics by 19F NMR

Here we explore a variety of monofluorinated and trifluoromethyl reporters in an effort to derive optimal tags for purposes of fluorine NMR studies of proteins. By examining fluorine NMR spectra in MeOH and water mixtures, we compared chemical shift sensitivity to solvent polarity. A bromo-acetamide functionalized monofluorinated pyridinol, which was designed to be specifically reactive towards thiols, was observed to exhibit an unprecedented range of chemical shift dispersions of 2.56 ppm in these solvents. A trifluoromethylated analog exhibited a chemical shift range of 1.67 ppm albeit with higher intensity and reduced linewidth. This may be contrasted with conventional fluorinated tags such as BTFA and BTFMA, whose dispersions are on the order of 0.57 and 1.03 ppm, respectively. We anticipate that these next-generation tags will greatly enhance prospects for fluorine NMR studies of proteins and fluorine NMR based drug discovery.

Keywords: 19F NMR
Small molecule
Tag
Advisor: Prosser, Scott
C-Terminus of HSP70 Interacting Protein as a Regulator of Parkin Translocation

Several genes implicated in Parkinson’s disease encode for proteins involved in the PINK1-Parkin pathway of mitochondrial clearance. The co-chaperone BAG proteins were previously shown to regulate this pathway as well as the co-chaperone CHIP. In this thesis, I determined which BAG proteins physically interact with CHIP and identified a novel interaction between CHIP and BAG4, a known regulator of Parkin translocation to the mitochondria. This interaction was dependent on the TPR domain of CHIP. Further, I demonstrated that CHIP is a potential regulator of the PINK1-Parkin pathway in that CHIP interacted with PINK1 and CHIP overexpression reduced Parkin translocation. I found that neither BAG4 nor the CHIP-BAG4 interaction were necessary for the effect of CHIP on Parkin translocation. I also found that CHIP knockdown did not increase Parkin translocation. This thesis provided initial work on how CHIP may regulate Parkin translocation and how co-chaperones control cell systems underlying Parkinson’s disease.

Keywords: BAG4
Chaperones
CHIP
Parkin
Parkinson's disease
PINK1
Advisor: Kalia, Lorraine
Development of CD200/CD200R Antibodies and Assessment of their Anti-tumor Potency

Immune system evasion in cancer contributes to the failure of host immune response against tumors. Immune escape may be caused by many factors, such as, the expansion of regulatory T cells, production of immunosuppressive cytokines by M2 (type-2 macrophages) or the over-expression of immunosuppressive molecules on tumor cells. CD200 is overexpressed in multiple cancers, and its interaction with CD200R transduces an immunoregulatory signal that can cause myeloid cell inhibition, allowing these CD200+ tumors to escape elimination by macrophages. Using phage-display technology, we developed a panel of synthetic anti-CD200 and CD200R antibodies. Their specificity, affinity, size exclusion profile, and ability to block the CD200:CD200R interaction was determined. Their anti-tumor potency was assessed by phagocytosis of tumor cells in vitro. Three out of four anti-CD200 antibody clones enhanced tumor phagocytosis by macrophages. Thus, synthetic anti-CD200 Abs may offer a new revenue for the treatment of various CD200-positive cancers through CD200:CD200R interaction blockade.

Advisor: Sidhu, Sachdev
Type 1 Interferon Limits Phagocyte Antimicrobial Function by Modulating Lysosomal Cholesterol

Listeria monocytogenes is a foodborne bacterial pathogen that is responsible for causing listeriosis in humans and animals. These infections can lead to severe disease such as meningitis and encephalitis, with a high mortality rate especially in the elderly and immunocompromised individuals. Prior studies have revealed that these bacteria can induce a type 1 interferon response that is deleterious to the host during systemic infection, while also affecting the intracellular life cycle of L. monocytogenes. However, the impact of type 1 interferon on innate cellular defenses to bacterial infections remain unclear. Here, we show that type 1 interferon can negatively impact the antimicrobial activity of macrophages. Type 1 interferon was found to cause cholesterol accumulation in lysosomes that alters their fusion with phagosomes, and also their ability to fuse with the plasma membrane in response to membrane damage. These findings help to explain how L. monocytogenes exploits type 1 interferon responses during infection.

Keywords: Bacteria
Cholesterol
Interferon
Lysosome
Phagocyte
Advisor: Brumell, John H
The Impact of Maternal High Fat Diet and Caffeine Exposure on Maternal and Offspring Health

Maternal malnutrition and resulting metabolic state is detrimental to offspring survival and increases offspring disease risk. Despite prevalence of maternal obesity and caffeine use during pregnancy, the effects on fetal outcomes are unclear. In this study, mice were fed with 60% high fat diet and/or 0.3g/L caffeine in water for 5 weeks prior to mating and through gestation and lactation. Caffeine effectively reduced high-fat diet induced weight gain however resulted in detrimental effects on offspring survival. Neurodevelopment and anxiety-like behaviours were altered in offspring born from obese dams using caffeine and this was correlated with reduction in maternal-pup interaction. These results highlight the differential effects of maternal caffeine on offspring health which are nutritional status dependent and may be mediated by changes in maternal care.

Keywords: Development
Diet
Maternal Fetal Medicine
Neuroscience
Obesity
Advisor: Feng, Zhong-Ping
Exploring Phosphorylation-independent Pathway of STAT5 Activation for Development of Small Molecule Inhibitors of STAT5

STAT5B is critical in the molecular pathogenesis of multiple blood cancers. The activation of STAT5B involves cytokine stimulation of a cell surface receptor. The intracellular receptor tail recruits a tyrosine kinase, which phosphorylates a tyrosine residue that is C-terminal to the SH2 domain of STAT5B followed by dimerization of STAT5B, and subsequent translocation to the nucleus to regulate gene expression. Currently, several therapeutic strategies are designed around inhibiting STAT5B phosphorylation, thereby preventing dimerization and downstream activation. However, recent studies have suggested a phosphorylation-independent mode of dimerization for STATs. Here we have examined the paradigm of phosphorylation-independent STAT5B dimerization. These studies suggest that in-vitro STAT5B dimerization is cysteine-mediated. We examined phosphorylation-dependent dimerization of STAT5B and utilized this to develop biophysical assays for screening differences in inhibitor binding. Finally, we examined the structural changes in the most frequently occurring disease-causing missense mutation, STAT5BN642H, which promotes phosphatase resistance and therefore enhances dimer lifetime.

Keywords: Cancer
cancer biology
Medicinal chemistry
rational drug discovery
STAT5B
STAT5B N624H
Advisor: Gunning, Patrick T
Generation and Characterization of Clinical Grade Induced Pluripotent Stem Cells (iPSCs) from Human Umbilical Cord Tissue Mesenchymal Stromal Cells (CT-MSCs)

Induced pluripotent stem cells (iPSCs) have had tremendous potential in the field of cell-based therapies, due to their unlimited capacity for proliferation and differentiation into any cell linage. For clinical use, it is important to make sure the cells are grown under Good Manufacturing Practice (GMP) by using an optimal starting cell source, an integration-free reprogramming method, and culturing the cells in feeder-free and xenogenic-free cell culture techniques. Mesenchymal stromal cells (MSCs) derived from the human umbilical cord tissue are a promising source for creating iPSCs as these cells can be stored for many years without the loss of viability and their collection is non-invasive. I have established a clinical grade protocol that produced feeder-free and integration-free human iPSCs from human umbilical cord MSCs. The iPSCs lines were successfully characterized through karyotyping, expression of pluripotency markers (OCT4, SOX2 and NANOG), and the formation of embryoid bodies (EBs) and teratomas.

Keywords: Reporgramming
Stem Cells
Umbilical Cord
Advisor: Rogers, Ian