VictorJuiz/thesis huggingface dataset:
Novel Approaches to Evaluating and Characterizing Force Sensor Performance at Body-device Interfaces

Force and pressure sensors are used to monitor fit and inform designers, researchers, and clinicians in various biomedical applications. However, sensor performance at the body-device interface is not well understood. The objective of this thesis was to develop and apply novel approaches to evaluating force sensor performance at clinically-relevant body-device interfaces. This work includes the characterization of existing transducers as well as the development of a novel sensor for assistive device applications. Clinically-relevant static and dynamic loading profiles were applied to two commercial sensors and the prototype sensor via a mechanical testing machine and an apparatus simulating the lower limb. The results of this study provide recommendations for use and summarize the effects of area of applied load, sensor configuration, tissue compliance, and calibration methods. This integration of force sensors is a vital first step towards adaptable, intelligent assistive devices that have the potential to improve fit, comfort, and performance.

Keywords: assistive devices
calibration
dynamic
interface pressure
pressure sensor
sensor evaluation
Advisor: Andrysek, Jan
Behdinan, Kamran
Facial Emotion Recognition in Individuals with Borderline Personality Disorder and First-degree Biological Relatives

Individuals with borderline personality disorder (BPD) show biases in their perceptions of facial emotional expressions. In studies that ask individuals with BPD to label or recognize emotional expressions, they frequently misattribute negative emotions to faces intended to convey no emotion and are less accurate at recognizing negatively-valenced emotional expressions. In the present study, we examined whether these emotion recognition findings are also present in individuals at familial risk for BPD. We administered a standardized measure of facial emotion recognition (FER) to 243 participants (probands, n=89; first-degree biological relatives, n=67; and controls, n=87). Our findings indicate that probands were slower and less accurate at identifying neutral faces compared to relatives and controls. Additionally, results indicated a misattribution bias wherein sad faces were mistaken as fearful more frequently in probands and relatives compared to controls. This is the first family study to investigate the extent to which the FER biases observed in individuals with BPD are familial.

Keywords: borderline personality disorder
facial emotion recogniton
family study
Advisor: Ruocco, Anthony C
Uliaszek, Amanda A
Maximally Additively Reducible Subsets of the Integers

Let A, B ⊆ N be two finite sets of natural numbers. We say that B is an additive divisor for A if there exists some C ⊆ N with A = B + C. We find which subsets of {0, . . . , k} have the most divisors, and prove a correspondence between additive divisors and lunar multiplication, introduced by Appelgate, LeBrun and Sloane [1] in their study of a kind of min/max arithmetic. We use this correspondence to prove conjectures of LeBrun et al. regarding the maximal number of lunar divisors.

Keywords: additive number theory
combinatorics
compositions
dismal arithmetic
lunar arithmetic
sumsets
Advisor: Burchard, Almut
Sac1 Regulates Distribution and Turnover of the Neph1 Ortholog Roughest in the Developing Drosophila Eye

The complex functions of cellular membranes depend on the distribution of crucial lipid species. Sac1 is a conserved ER-localized phosphatase whose substrate, phosphatidylinositol 4- phosphate (PI4P), coordinates secretory pathway and plasma membrane function. PI4P from multiple pools is delivered to Sac1 by oxysterol binding protein (OSBP) family proteins in exchange for phosphatidylserine and sterols, which places Sac1 at the intersection of multiple lipid distribution pathways. However, much remains unknown about Sac1’s roles in subcellular homeostasis and organismal development. In Drosophila, reduced Sac1 activity in a temperature-sensitive mutant (Sac1ts) disrupts cellular patterning during eye morphogenesis. I found that the adhesion protein Roughest, which coordinates key patterning steps, is rapidly turned over during patterning. At later stages, Roughest accumulates in Sac1ts retinas due to a defect in endo-lysosomal trafficking and degradation. This highlights a new facet of Sac1 function, which could potentially have broader consequences for cell physiology, development and disease.

Advisor: Brill, Julie A
Effect of Vitamin C on Nitroglycerin Mediated Vasodilation in Individuals with and without the Aldehyde Dehydrogenase 2 Polymorphism

The mechanism of the bioactivation of nitroglycerin is controversial. Several enzymatic pathways have been suggested but there has been no consensus. The mitochondrial aldehyde dehydrogenase (ALDH-2) has now emerged as the primary enzyme bioactivation at therapeutically relevant concentrations. However human studies have yielded inconsistent results regarding the essential role of ALDH-2 in GTN bioactivation. We investigated the vascular response to nitroglycerin given over a wide range of concentrations in subjects with and without the ALDH-2 Glu504Lys polymorphism. We also examined the effect of supplemental Vitamin C on vascular responses to GTN in those with and without the ALDH-2 polymorphism. Forearm blood flow (FBF) responses to a brachial artery infusion of nitroglycerin were assessed using venous occlusion plethysmography. We conclude that ALDH-2 is involved in GTN bioactivation, and vitamin C co-infusion did not restore the vascular response to GTN in those that are ALDH-2 deficient.

Keywords: ALDH-2
Antioxidant
Bioactivation
Hemodynamic Response
Nitroglycerin
Polymorphism
Advisor: Parker, John D
Elucidating the Role of Histone Acetylation in Regulating Neutrophil Extracellular Trap Formation

Neutrophils undergo a unique form of cell death to generate neutrophil extracellular traps (NETs). However, the importance of histone acetylation (e.g., acetylated histone H4, AcH4) in NET formation (NETosis) has not been established. Belinostat and panobinostat are pan histone deacetylase inhibitors (HDACis) and are widely used in clinical and laboratory applications. However, the relevance of these HDACis in altering neutrophil death is yet unknown. We considered that HDACis-induced AcH4 would dose-dependently alter neutrophil cell death between NETosis and apoptosis. The presence of HDACis (≤0.25 µM Belinostat; ≤0.04 µM panobinostat) significantly induced AcH4 and NETosis without promoting reactive oxygen species (ROS) production. Increasing concentrations of HDACis (>1 µM belinostat; >0.2 µM panobinostat) further induced H4 acetylation, NOX-derived ROS production, and significantly inhibited NETosis and induced apoptosis. However, in the presence of NETosis-inducing stimuli, higher concentrations of HDACis limited both NETosis and Apoptosis. Therefore, HDACis differentially regulate both NETosis and neutrophil apoptosis.

Keywords: epigenetics
histone acetylation
histone deacetylase inhibitors
neutrophil extracellular trap formation
neutrophils
post translational modification
Advisor: Palaniyar, Nades
Investigating a Photothrombotic Pediatric Rodent Stroke Model using MRI Histology

Pediatric stroke has emerged as an important cause of neurological disability in children. Animal studies of ischemic stroke show differences in lesion evolution and blood-brain barrier (BBB) permeability between adult and neonatal rodents. However, little is known about stroke evolution at the juvenile stage. Our study aimed to both qualitatively and quantitatively assess photothrombotically-induced stroke progression in juvenile rats using longitudinal MRI and histology. The assessment involved 1) characterizing the lesion and penumbra evolution; and 2) characterizing degree of BBB disruption. Our results over a 7-day period indicated lesion persistence and penumbra transformation into necrosis, as well as BBB disruption persistence. Our in-vivo and ex-vivo results provide insight into disease progression over time and could serve as a study model to test BBB stabilization agents for future clinical application in the pediatric setting.

Keywords: Animal research
Blood-brain barrier
Brain
Histological staining
Ischemic stroke
MRI
Advisor: Kassner, Andrea
A Comparative Study of Different Plasma Gases on Twin Wire Arc Spray Characteristics

Oxidation during plasma spray coating is a known factor affecting coating qualities. This thesis outlines a comparative approach used to investigate how the oxygen content of plasma forming gas affects the composition of the coatings utilizing a Twin Wire Arc plasma spray torch. Firstly, this paper looks at the effects on the plasma plume and wire melting using high speed imagery. Secondly, it analyzes the oxidation of particles captured from flight. Thirdly, it investigates the oxidization of coatings sprayed at select distances from the torch by analyzing cross-sections for oxidation. Correlation of the results provides an improved understanding of the level of oxidation for composite alloy wires within the plasma spray process.

Keywords: Coating Oxidation
Oxidation
Plasma
Plasma Forming Gas
Spray Coating
Twin Wire Arc
Advisor: Mostaghimi, Javad
Electrophoretic Deposition of Bioactive Nanoparticles for Disinfection of Apical Root Canal Anatomy

Objective: To utilize the principles of electrophoresis to transport and deposit cationic nanoparticles in apical root canal anatomy for enhanced antibacterial effect. Materials and Methods: The novel technological approach was assessed in two phases: i) an infected dentin block model and ii) an infected root canal model. Specimens were subjected to treatment with either: 1) electric field 2) cationic nanoparticles or 3) combined treatment. The specimens were analyzed using microbiological methods and scanning electron microscopy (SEM). Results: The results of both phases yielded a greater antibacterial effect in specimens subjected to a combined treatment with cationic nanoparticles and electric field (p

Keywords: Dentistry
Disinfection
Electrophoresis
Endodontics
Nanoparticles
Root Canal
Advisor: Kishen, Anil
Role of TASK-1/3 Channels at the Hypoglossal Motor Nucleus in Modulating Motor Output

Tongue muscle tone, important for upper airway patency, is reduced during sleep due to the withdrawal of excitatory inputs to the hypoglossal motor nucleus (HMN). These wake-active neurotransmitters all inhibit TWIK-Related Acid-Sensitive Potassium (K+) leak (TASK-1/3) channels on hypoglossal motor neurons in vitro, increasing motor activity. We hypothesize that inhibition of hypoglossal TASK-1/3 channels will increase tongue muscle activity in-vivo, and modulate the responses to applied 5-HT, one such wake-active neurotransmitter. We microperfused the HMN of rats with several TASK-1/3 channel modulators and measured the resulting tongue muscle output, with or without co-applied 5-HT. Furthermore, the effects of 5-HT at the HMN were measured in mice lacking TASK-1/3 channels on hypoglossal motor neurons. This thesis identifies that TASK-1/3 channel modulation at the HMN does not modulate tongue muscle output or its response to 5-HT, suggesting that TASK-1/3 channels are not a suitable target for tongue muscle reactivation during sleep.

Advisor: Horner, Richard L
Effects of Resveratrol on Peri-implant Bone Healing

Resveratrol has demonstrated positive effects on osteogenesis and angiogenesis and may provide benefits in peri-implant wound healing. We employed a model where differences in osseointegration parameters can be demonstrated using implants of different surface topographies. Micro-surfaced and nano-surfaced implants were implanted in rat tibiae and subjected to disruption testing at five timepoints. Subcutaneous resveratrol injections were delivered weekly. Data were analyzed by curve fitting to mathematical functions that comprised of maximum disruption force C, and time constant tau, defined as time required to reach 63.2% of C. Nano-surfaced implants produced greater C values than micro-surfaced as expected, thus confirming validity of the model. Nano-surfaced implants also demonstrated lower tau values, suggesting faster osseointegration rates. Contrary to expectations, resveratrol produced a general trend of lower C and greater tau, which were not statistically significant but approached significance. Overall, resveratrol did not produce beneficial effects on implant osseointegration within this study.

Advisor: Mendes, Vanessa
Davies, John E
Is there Astrocyte Pathology in Posttraumatic Stress Disorder (PTSD)? Preliminary Findings of a PET Study with the Monoamine Oxidase B Radioligand [C-11]SL25.1188

Background: There is a lack of in vivo studies investigating astrocytes in posttraumatic stress disorder. We used positron emission tomography (PET) of the monoamine oxidase B (MAO-B) probe [C-11]SL25.1188.1188 (an index of astrocytes) to explore whether MAO-B binding is lower in PTSD and related to symptoms. Methods: [C-11]SL25.1188/PET binding was measured in 13 PTSD subjects and 17 healthy controls. Results: [C-11]SL25.1188 binding was marginally decreased in PTSD. A Group by ROI interaction suggested lower [C-11]SL25.1188 binding in ventral striatum (p =0.09) with marginal decreases in the frontal areas. [C-11]SL25.1188 binding was lower in PTSD with comorbid MDD. No relationship between [C-11]SL25.1188 and clinical features was found. Conclusion: Our preliminary findings are partly in line with preclinical literature suggesting loss of astrocytes following stress paradigms that model both PTSD and MDD. Replication of these findings in a larger cohort using stratified sampling is warranted.

Keywords: Astrocyte
MAO-B
PET
PTSD
Advisor: Boileau, Isabelle
Biomolecular Nanoparticle Assemblies

Due to their scale, nanoparticles have great potential to treat and diagnose of diseases. Despite early promise, few nanoparticle treatments have made it past the trial phase and into the clinic. This is partially due to our lacuna of knowledge on the interactions of nanoparticles with biomolecules such as proteins and our lack of control over nanoparticle physicochemical properties following administration. This thesis attempts to address both concerns by studying nanoparticle assemblies formed with biomolecules. We begin by studying the complexes formed between sub-10 nm nanoparticles and proteins to determine which component acts as the carrier and how that affects the complexes’ biological interactions. We then apply this knowledge to design nanoparticle assemblies connected by nucleic acids that can change shape in response to biological stimuli. This research provides a foundation for new nanoparticle designs that can overcome the biological barriers that have so far frustrated the field of nanomedicine.

Keywords: DNA nanotechnology
Gold nanoparticle
Nanomedicine
Protein corona
Shapeshifing
Ultrasmall
Advisor: Chan, Warren CW
Mitochondrial Dynamics in Mesenchymal Cells in Placental Development and Preeclampsia

Cellular health hinges on functional mitochondrial networks that are maintained by fusion protein Optic Atrophy 1 (OPA1) and fission protein Dynamin Related Protein 1 (DRP1). Preeclampsia (PE) is a serious pregnancy disorder where exuberant fission events contribute to trophoblast cells demise. Placental mesenchymal stromal cells (pMSCs) are critical for placenta development. We hypothesized that the mitochondrial dynamic events in pMSCs are kept in balance across gestation and that this balance is disrupted in PE. We discovered the low physiologic oxygen in the first trimester placenta produce small and functional mitochondria. Conversely, in PE exuberant fission were related to mitophagy. Healthy mitochondrial fission was attributed to the lysosome, whereas secondary lysosomes in PE degrade damaged mitochondria. In conclusion, during placental development physiologic changes in oxygen regulate mitochondrial dynamic events to maintain their function, however in PE excessive fission impair pMSCs function and contributes to poor placental development.

Keywords: Hypoxia
Mitochondrial Dynamics
Placenta
Placental Mesenchymal Cells
Preeclampsia
Advisor: Caniggia, Isabella
Long-term Caries Relapse following Dental Treatment under General Anesthesia

This retrospective cohort study included 261 patients that received dental treatment under GA at a private pediatric dentistry practice in Southwestern Ontario. Data comprised of patient/caregiver and treatment factors for each subject. Caries relapse over long-term follow-up, along with associations with the collected variables were evaluated. Survival analysis found CR rates of 48% and 71% at 24 months and 48 months post-GA, respectively. Caries relapse was found to be significantly associated with active children, more multisurface composite restorations, and more remaining surfaces available for caries post-GA. Patients treated under GA in the mixed dentition were 75% less likely to experience CR compared to those in primary dentition. Caries relapse rates post-GA were high in this sample of children, suggesting that conventional surgical approaches to managing ECC is not controlling the disease process. Identifying risk factors for caries relapse may influence treatment and risk management decisions.

Keywords: caries relapse
dental caries
general anesthesia
pediatric dentistry
relapse
risk factors
Advisor: Quiñonez, Carlos
Friedman, Clive
Investigating the Cellular and Molecular Correlates of Malignancy in Li-Fraumeni Syndrome

Li-Fraumeni Syndrome is a cancer predisposition syndrome associated with germline TP53 mutations. LFS patients are faced with a significant lifetime cancer risk, which necessitates the identification of cancer prevention strategies. Chemical mTORC1 inhibitors delay cancer onset and extend lifespan in LFS mice, suggesting that mTORC1 favors tumorigenesis in LFS. We show that LFS patient-derived fibroblasts harboring the R248Q p53 mutation exert a pro-tumorigenic influence when co-injected with cancer cells into mice. This influence was negated by rapamycin, suggesting that this pro-tumorigenic phenotype is mTORC1-dependent. To that end, mutant fibroblasts exhibit increased mTORC1 activity and vulnerability to mTORC1 inhibition compared to p53 wildtype fibroblasts. We further show that the secretome of mutant versus wildtype fibroblasts differs, and secretion of certain pro-tumorigenic cytokines is mTORC1-dependent. Our findings suggest that mutant-p53 driven mTORC1 activation promotes a functional dependency on mTORC1 signaling, revealing a vulnerability that may exploited to limit the oncogenicity of mutant p53.

Keywords: Li-Fraumeni Syndrome
mTORC1
p53
Tumorigenesis
Tumour microenvironment
Advisor: Malkin, David
Role of Notch Signaling in the Differentiation of Human Lung Progenitor Cells to Alveolar Epithelial Type II Cells

Human lung development is a complex process guided by specific tissue interactions and cellular signaling. Attempts to generate cell-based model systems of the alveolar region of the lung have relied on recapitulating the biological environment within which these cell types exist. Utilizing an in vitro directed differentiation approach, this thesis demonstrates the efficient differentiation of human induced pluripotent and embryonic stem cells to NKX2-1+ lung progenitor cells and subsequent SFTPC+ alveolar epithelial type II (ATII) cells. With the aim of improving ATII cell differentiation efficiency, the role of Notch signaling throughout lung progenitor and ATII cell differentiation was investigated. Under the specific conditions tested, pharmacological inhibition of Notch signaling did not significantly improve our ability to derive ATII cells. However, a decrease in basal and secretory epithelial cell markers following Notch inhibition suggests that Notch signaling is important in the commitment of lung progenitor cells to specific proximal cell lineages.

Keywords: Alveolar Epithelial Type II Cells
Lung Development
Notch Signaling
Organoids
Advisor: Post, Martin
Teaching Sustainability to Culinary Students: Graduating Sustainability-minded Chefs?

In 2016, The Ministry of Training, Colleges and Universities upon negation with food industry and culinary educational institutions’ stakeholders, mandated that culinary colleges across Ontario implement sustainability into their required program outcomes. Positioning the potential impacts of a chef’s actions on food production, consumer choice and food service operations’ management is crucial in assisting students to develop a sustainable mindset as future culinary leaders. This thesis aims to explore “The Sustainable Chef” course, offered by one of Toronto’s main culinary colleges, to assess its potential to assist culinary schools become vital sites to promote a new sustainable kitchen and food culture. Furthermore, graduating sustainability-minded chefs who are aware of their economic, social and environmental responsibilities as participants of the food system will help to drive change in the industry.

Keywords: Chefs de Cuisine
Culinary Arts Education
Food Culture
Food Studies
Food Systems
Sustainability
Advisor: Sumner, Jennifer
Menthol Mouth Rinsing Improves Cycling Performance in Females under Heat Stress

This study investigated the effects of a menthol mouth rinse on performance and physiological responses in female cycling athletes during a 30-km individual time trial (ITT). Participants (n=9) cycled for 30-km in hot conditions (30 ± 0.6 °C, 70 ± 1% relative humidity, 12 ± 1 km/h windspeed) on two test occasions using a menthol (MEN) mouth rinse (MR) occurring every 5-km. Perceptual responses (perceived exertion and thermal perception) were recorded at 5, 10, 15, 20, 25, and 30-km. The MEN MR significantly improved ITT performance by 2.3 ± 2.7% relative to PLA (p= 0.034, d= 0.85, 95% CI= 8.43 to 166.9). There were no significant differences in perceived exertion and thermal perception. These results demonstrate that a non-thermal cooling agent can improve physiological performance in moderately trained female cyclists with no change in perceived exertion or thermal perception.

Keywords: Heat stress
Menthol
Perception
Thermoregulation
TRPM8
Advisor: Thomas, Scott G
Development of Electrochemical Sensors using Novel Nanocomposites

Modification of electrode surfaces with nanomaterials, polymer films, nanoparticles, nanocomposites, and self-assembled monolayers (SAMs) is a popular approach for improving the performance of electrochemical sensors. Nanomaterial modified electrodes are able to offer improved performance due to improvement in the electron transfer kinetics that occurs at the interface of these electrodes, increases in the electrochemically active surface area, electro-catalytic effects facilitated by the nanomaterials, and changes in the surface geometry. In this thesis, two such electrode modifications have been reported. In the first work, simultaneous electrochemical detection of ascorbic acid (AA), dopamine (DA), and uric acid (UA) was performed using a modified graphite paste electrode (MGPE) with epigallocatechin gallate (EGCG) and green tea (GT) powder. In the second work, multi-walled carbon nanotube-reduced graphene oxide (MWCNTrGO) nanocomposite-modified glassy carbon electrodes (GCEs) were used for the electrochemical detection of gallic acid-capped gold nanoparticles (GA-AuNPs) using differential pulse voltammetry (DPV).

Keywords: carbon nanotubes
differential pulse voltammetry
electrochemical impedance spectroscopy
electrode modifications
graphene
nanocomposites
Advisor: Kerman, Kagan