Life Sciences Commons^™

Head Impact Exposures In Youth Canadian Football Players Aged 12-14 Do Not Significantly Impair Antisaccade Performance, William J. Smith

Electronic Thesis and Dissertation Repository

There is a growing body of research evaluating head impacts in sport, but studies have not evaluated youth football in Canada. It is important to evaluate football in Canada as the rules and field size are different than American football, and this may influence the impact exposures. The purpose of this study was to quantify the head impact exposures in youth Canadian football and determine if a season’s worth of impacts could cause impairments in executive function. Players (n=50) had their head impacts recorded using an impact measuring device (GForceTracker) throughout all contact practices and games. A subset ...

Investigation Of Flow Disturbances And Multi-Directional Wall Shear Stress In The Stenosed Carotid Artery Bifurcation Using Particle Image Velocimetry, Amanda L. Dicarlo

Electronic Thesis and Dissertation Repository

Hemodynamics and shear forces are associated with pathological changes in the vascular wall and its function, resulting in the focal development of atherosclerosis. Flow complexities that develop in the presence of established plaques create environments favourable to thrombosis formation and potentially plaque rupture leading to stroke. The carotid artery bifurcation is a common site of atherosclerosis development. Recently, the multi-directional nature of shear stress acting on the endothelial layer has been highlighted as a risk factor for atherogenesis, emphasizing the need for accurate measurements of shear stress magnitude as well direction. In the absence of comprehensive patient specific datasets numerical ...

Top-Down And Bottom-Up Effects On Collembola Communities In Soil Food Webs, Jordan Kustec

Electronic Thesis and Dissertation Repository

Anthropogenic changes are causing shifts within soil food web communities, which may alter ecosystem processes such as nutrient cycling, carbon storage and decomposition. I quantified ecological stressor effects on the abundance, richness, community composition and body size of a soil-dwelling microarthropod (Collembola: Hexapoda). I quantified the effects of warming and nitrogen deposition in two separate field studies and demonstrated that warming shifts Collembola community structure and decreases community body size. I quantified the interactive effects of top-down and bottom-up forces mediated by warming as ecological stressors in Collembola communities. I found that bottom-up effects of nutrient addition did not affect ...

True North Strong Canada 150: Canadian Identity And Its Contribution To Doping Free Sport, Helena A. Hlas

Electronic Thesis and Dissertation Repository

This thesis, a reflective piece inspired by “Canada 150” events, explores the psychosocial and sociocultural factors surrounding the ongoing evolution of the clean sport movement in Canada. A literature review recounts the critical events in the history of doping, viz. the Ben Johnson scandal, which resulted in a call to overhaul sport culture and realign it with fair play values. Theories in sports philosophy and psychology provide a further understanding of the meaning of sport, and psychosocial factors that are inextricably linked to doping behavior, respectively. The autoethnographic method provides insight into current Canadian values to compare with those in ...

Suberin Biosynthesis And Deposition In The Wound-Healing Potato (Solanum Tuberosum L.) Tuber Model, Kathlyn Natalie Woolfson

Electronic Thesis and Dissertation Repository

Suberin is a heteropolymer comprising a cell wall-bound poly(phenolic) domain (SPPD) covalently linked to a poly(aliphatic) domain (SPAD) that is deposited between the cell wall and plasma membrane. Potato tuber skin contains suberin to protect against water loss and microbial infection. Wounding triggers suberin biosynthesis in usually non-suberized tuber parenchyma, providing a model system to study suberin production. Spatial and temporal coordination of SPPD and SPAD-related metabolism are required for suberization, as the former is produced soon after wounding, and the latter is synthesized later into wound-healing. Many steps involved in suberin biosynthesis remain uncharacterized, and the mechanism ...

Landscape-Level Effects Of Agricultural Intensification On The Condition And Diet Of Nestling Barn Swallows (Hirundo Rustica), Jackson W. Kusack

Electronic Thesis and Dissertation Repository

Farmland bird populations have experienced declines with increasing agricultural intensification for which the leading hypothesis is a reduction of prey insects. This may be especially relevant for aerial insectivores whose primary diet is aerial insects. For this thesis, I examined nestling body condition and used stable isotopes (δ¹³C, δ¹⁵N) and fecal DNA barcoding to determine the diet of a farmland breeding aerial insectivore, the Barn Swallow (Hirundo rustica), within an agro-ecosystem in Southern Ontario, Canada. Nestling body condition was positively affected by agricultural intensification, but all benefits were lost by the pre-fledging stage and with no ...

Expression Of Hepatic Cytochrome P450 Drug Metabolizing Enzymes In Diabetes And Diabetic Nephropathy, Cheng Jay Fang

Electronic Thesis and Dissertation Repository

The prevalence of diabetes worldwide is rapidly increasing. Polypharmacy, along with a high risk of adverse drug reactions, is common in diabetic patients. Cytochrome P450 (CYP) 3A and 2C drug metabolizing enzymes are reduced in chronic kidney disease (CKD), altering drug pharmacokinetics and contributing to adverse drug reactions. A large fraction of commonly prescribed drugs are metabolized by CYP3A and CYP2C. Approximately 40% of all CKD cases are attributed to diabetic nephropathy (DN) and early DN presents as mild kidney disease. This study aims to evaluate the impact of diabetes and DN on levels and activity of hepatic CYP3A and ...

The Use Of Current Steering During Subthalamic Deep Brain Stimulation To Alleviate Upper Limb Symptoms Of Parkinson's Disease, Shabna Iftikar Mohideen

Electronic Thesis and Dissertation Repository

Subthalamic (STN) deep brain stimulation (DBS) is an established treatment to alleviate the appendicular motor symptoms of Parkinson's Disease (PD). Current steering during DBS allows the unequal fractionation of current between two electrodes on the lead, resulting in a non-spherical electrical field. It is hypothesized that the way the electrical field is shaped will affect a patient’s upper limb symptom alleviation. Seven PD patients who underwent bilateral STN-DBS were tested over four weeks post-operation. 16 current fractionation settings were tested each week at an amplitude that increased weekly. Optimal setting was defined as the setting that provided the ...

Hitchhiker's Guide To Migration: Effects Of Experimental Parasitic Infection And Other Immune Challenges On Migratory Traits Of Sparrows, Tosha R. Kelly

Electronic Thesis and Dissertation Repository

Seasonal migration exposes animals to a variety of habitats and parasites, and if infected migratory birds migrate successfully there is great potential for birds to transport infectious diseases long distances. Our current understanding of whether birds contribute to the spread of disease relies upon observational field studies that are limited in their ability to discern cause from effect. Using captive and field-based experiments for my doctoral research, I answered three research questions: (1) are nocturnal migratory restlessness (Zugunruhe) and body condition affected by mounting an acute phase immune response during migration; (2) what are the impacts of parasitic infection on ...

The Effect Of Multiple Environmental Stressors On The Growth And Toxicity Of The Red Tide Alga Heterosigma Akashiwo, Malihe Mehdizadeh Allaf

Electronic Thesis and Dissertation Repository

Heterosigma akashiwo (Y.Hada) Y.Hada ex Y.Hara & M.Chihara is a golden-brown phytoflagellate with high potential to kill fish. These cells create large, nearly mono-specific blooms that persist from weeks to months. Although bloom persistence and frequency remain a mystery, environmental factors such as light, temperature, salinity and CO₂ level are proposed as drivers for both bloom initiation and toxicity. As timing and locations of nature blooms are difficult to predict, most of the information on this species comes from laboratory experiments on isolated cells. In this age, when multiple stressors occur simultaneously the traditional “One-factor-at-a-time” (OFAT ...

Predicting Response To Platin Chemotherapy Agents With Biochemically-Inspired Machine Learning, Peter Rogan, Eliseos J. Mucaki, Dan Lizotte

Biochemistry Publications

Selection of effective genes that accurately predict chemotherapy response could improve cancer outcomes. We compare optimized gene signatures for cisplatin, carboplatin, and oxaliplatin response in the same cell lines, and respectively validate each with cancer patient data. Supervised support vector machine learning was used to derive gene sets whose expression was related to cell line GI₅₀ values by backwards feature selection with cross-validation. Specific genes and functional pathways distinguishing sensitive from resistant cell lines are identified by contrasting signatures obtained at extreme vs. median GI₅₀ thresholds. Ensembles of gene signatures at different thresholds are combined to reduce dependence ...

Magnetic Field Frequency-Response For Human Magnetophosphene Perception And Associated Eeg Modulations, Cadence M. Baker

Electronic Thesis and Dissertation Repository

Background: Magnetophosphenes are among the most reliably reported effects resulting from magnetic induction. The frequency dependence of the perception threshold is crucial, as guideline agencies use this information to set exposure limits whose purpose is to protect public and workers.

Objective:Establish the magnetophosphene perception thresholds throughout the extremely low frequency range (0-300 Hz) and evaluate the use of EEG as a biomarker.

Hypothesis:Perception thresholds will be lowest at ~30 Hz. EEG occipital alpha power will decrease upon perception.

Methods:60 participants were exposed to homogenous magnetic fields up to 300 Hz, and 70 mT. EEG alpha power was ...

Growth And Toxicity Of Geographically-Distinct Isolates Of The Fish-Killing Phytoflagellate, Heterosigma Akashiwo, Veerta Singh

Electronic Thesis and Dissertation Repository

Harmful Algal Blooms (HABs)—an accumulation of toxic phytoplankton—often result from environmental changes reflecting the increasing global human footprint and climate change. One HAB species drawing attention is Heterosigma akashiwo, a fish-killing flagellate that can cause extensive fish loss or be benign, depending on location or environmental conditions. Here, I investigate if this difference in toxicity is regulated by environmental conditions or differences in cellular physiology. Six strains were examined. Three originate from the Salish Sea, where fish-kills are common, and three from Japan, where blooms of Heterosigma are common but fish-kills are rare. By measuring growth and toxicity ...

Learning Expands The Preplanning Horizon In Finger Sequence Tasks, Neda Kordjazi

Electronic Thesis and Dissertation Repository

Many everyday skills involve the production of complex sequences of movements. However, the dynamics of the interplay between action selection and execution processes in sequential movements is poorly understood.Here, we set out to investigate the extent to which information regarding upcoming actions is utilized by the motor system to preplan into the future and furthermore, how this ability is influenced by learning. We designed a finger sequence taskwhere participants were shown only a fixed number of upcoming cues regarding future presses in every trial (viewing window, W). W varied between 1 (next digit revealed with pressing the current digit ...

Immunization With Recombinant Myelin Oligodendrocyte Glycoprotein Identifies Autoreactive T Cells As A Limiting Factor In Autoreactive Germinal Center Maintenance, Rajiv William Jain

Electronic Thesis and Dissertation Repository

Germinal center (GC) responses are responsible for the protection provided by immunizations but can also drive autoimmunity. B and T cells collaborate in the GC to target the same antigen (Ag) to inform B cell differentiation; however, the properties of Ags differ substantially in autoimmunity and foreign-Ag driven immunity. Currently, it is not well understood how properties of the Ag itself influence the initiation or progression of GC responses, limiting our ability to develop effective vaccinations and predict the progression of autoimmune responses. The purpose of this thesis is to assess how GC responses initiate and progress when immunizing with ...

Cardiodynamic Associations With Resilience In Undergraduate Students And The Effect Of A Mentorship Intervention, Rachel J. Knetsch

Electronic Thesis and Dissertation Repository

The National College Health Assessment (NCHA) indicates that a majority of Canadian university students report feeling overwhelmed, stressed, and anxious during their undergraduate studies. Resilience refers to positive adaptation, or the ability to maintain or regain mental health, despite experiencing adversity (Herrman et al., 2011). While autonomic indices have been used to describe chronic physiological stress, the role of heart rate variability (HRV) as an index of resilience remains unclear. This research tested the hypotheses that (1) there is a relationship between HRV and resilience scoresand (2) a mentorship intervention will improve HRV and resilience outcomes. Fifty-seven first year students ...

A Comprehensive Catalog Of Post-Translational Modifications Of Drosophila Melanogaster Hox Protein, Sex Combs Reduced, Anirban Banerjee

Electronic Thesis and Dissertation Repository

During formation of the anterior-posterior axis, Homeotic selector (HOX) proteins determine the identity of Drosophila body segments. HOX proteins are transcription factors that regulate gene expression during development. Besides a highly conserved DNA-binding homeodomain (HD), HOX proteins also contain functionally important, evolutionarily conserved small motifs. These short motifs found in HOX proteins may be Short Linear Motifs (SLiMs). SLiMs are proposed to be sites of phosphorylation and this may regulate the activity of HOX proteins. The primary aim of this work was to develop a comprehensive catalogue of the sites of phosphorylation and other post-translational modifications (PTMs) for Fushi tarazu ...

The 2Β Insert Perturbs Folding, Stability And Hydrophobic Exposure Of Stromal Interaction Molecules, Steve Chung

Electronic Thesis and Dissertation Repository

Stromal interaction molecule (STIM)1 and 2 regulate agonist-induced and basal cytosolic calcium (Ca2+) levels through oligomerization and translocation to endoplasmic reticulum (ER)-plasma membrane (PM) junctions. At these junctions, the STIM cytosolic coiled-coil domains couple to PM Orai1 protein subunits to form Ca2+ released activated Ca2+ (CRAC) channels that facilitate store-operated Ca2+ entry (SOCE). One splice variant of STIM2, STIM2β, contains an extra 8-residue (2β insert) located within the coiled-coils and inhibits SOCE through an unresolved mechanism, adding another layer of complexity to Ca2+ regulation in mammals. I hypothesize that the 2β insert perturbs the coiled-coil conformation and dynamics ...

The Effects Of Perceived Predation Threat On Stress Response And Memory In Birds, Chlöe S. N. Carter

Electronic Thesis and Dissertation Repository

This study examined how perception of predator cues, across three sensory modalities, affects physiology and behaviour of songbirds. I hypothesized that the perception of predator threat would elicit physiological and behavioural responses in both acute and chronic exposure conditions. My first study examined the responses of wild-caught black-capped chickadees (Poecile atricapillus) and house sparrows (Passer domesticus), as well as lab-bred zebra finches (Taeniopygia guttata), to acute predation cue exposure by coding video recorded behaviour and corticosterone analysis. My second study examined changes in black-capped chickadees’ foraging behaviour and memory retention after chronic exposure to acoustic predation cues. There were no ...

Effects Of Maternal Protein Restriction On The Pulmonary Surfactant System During The Early Life And Adulthood, Reza Khazaee

Electronic Thesis and Dissertation Repository

Fetal growth restriction (FGR) is defined by low birth weight and contributes to a variety of adult-onset diseases with different severities between males and females. However, the effects of FGR on the pulmonary surfactant are not fully elucidated. In this thesis, first, we investigated the FGR effects on the lung function and the surfactant system at the early postnatal life. It was hypothesized that FGR contributes to alterations of lung mechanics and the surfactant system during the neonatal period. Second, we assessed the FGR effects on the surfactant system in response to sepsis in adulthood. It was hypothesized that FGR ...

Adaptation Mechanisms Of Two-Spotted Spider Mite, Tetranychus Urticae, To Arabidopsis Indole Glucosinolates, Golnaz Salehipourshirazi

Electronic Thesis and Dissertation Repository

The two-spotted spider mite Tetranychus urticae Koch is a key agricultural pest that causes significant yield losses in a wide range of economically important crops. Rapid development of resistance to several classes of pesticides in T. urticae necessitates introduction of alternative management strategies to control this pest. Indole glucosinolates (IGs) are secondary metabolites found in Brassicaceae plants (including Arabidopsis thaliana) that have been shown to be effective against T. urticae and could be potential candidates to control spider mites. However, a laboratory population selected on IG-containing Arabidopsis was able to evolve adaptation to this plant. The overall objective of this ...

Cannabinoid Transmission In The Basolateral Amygdala Modulates Prefrontal Cortex And Ventral Hippocampal Activity, Brian J. Pereira

Electronic Thesis and Dissertation Repository

The cannabinoid system is important for maintaining neuron-to-neuron communication within the mammalian brain. One of the most commonly used substances to alter the cannabinoid system is cannabis. Individuals who are exposed to cannabis report having dissociable effects; both positive and negative. High amounts of THC have been commonly associated with the negative effects of cannabis, whereas CBD can be used to counter these. Pre-clinical evidence suggests that the combination of the two compounds can produce a therapeutic benefit for individuals who are susceptible to the effects of THC. The present study investigates whether the combination of THC+CBD can prevent ...

Dna Sequence Classification: It’S Easier Than You Think: An Open-Source K-Mer Based Machine Learning Tool For Fast And Accurate Classification Of A Variety Of Genomic Datasets, Stephen Solis-Reyes

Electronic Thesis and Dissertation Repository

Supervised classification of genomic sequences is a challenging, well-studied problem with a variety of important applications. We propose an open-source, supervised, alignment-free, highly general method for sequence classification that operates on k-mer proportions of DNA sequences. This method was implemented in a fully standalone general-purpose software package called Kameris, publicly available under a permissive open-source license. Compared to competing software, ours provides key advantages in terms of data security and privacy, transparency, and reproducibility. We perform a detailed study of its accuracy and performance on a wide variety of classification tasks, including virus subtyping, taxonomic classification, and human haplogroup assignment ...

The Post-Fledging Survival And Movements Of Juvenile Barn Swallows (Hirundo Rustica): An Automated Telemetry Approach, Dean R. Evans

Electronic Thesis and Dissertation Repository

For migratory songbirds, population dynamics are primarily influenced by juvenile or first year survival, but survival between fledging and fall migration is particularly important. Unfortunately, our knowledge of this post-fledging period is largely limited due to the difficulty of tracking juveniles outside the nest. For this thesis, I used automated radio telemetry to track the survival and post-fledging movements of 216 juvenile Barn Swallows (Hirundo rustica) from fledging up until departure for autumn migration in 2016-2017. Average apparent survival was 42% for both broods and nestlings in better body condition had higher survival. Nestlings from second broods migrated 21 days ...

Hierarchical Variation In Cellulose Decomposition Across Southern Ontario Reference Streams, Jenna R. Webb

Electronic Thesis and Dissertation Repository

The cotton strip assay (CSA) has been promoted as a method of incorporating functional indicators into standardized river assessments by study of organic-matter decomposition. However, operationalization of the CSA as an indicator requires testing the spatial and temporal controls of variance associated with decomposition of cotton strips at regional reference sites. I conducted a hierarchically structured study of decomposition rates in Ontario, Canada. Cotton strips were deployed during the spring, summer and fall in pool and riffle habitats of 22 streams located in three distinct physiographic regions. Partitioning of variation among hierarchical scales associated with rates of decomposition were examined ...

The Effect Of Anoxia On Mitochondrial Function In A Hibernator (Ictidomys Tridecemlineatus), Leah Hayward

Electronic Thesis and Dissertation Repository

Hibernation protects mammalian tissues against ischemia-reperfusion injury, but the underlying biochemical mechanisms are unknown. I hypothesized that the mechanisms allowing for mitochondrial metabolic flexibility during hibernation permit anoxia tolerance and contribute to tissue ischemia-reperfusion tolerance. I assessed mitochondrial performance before and after five minutes of anoxia in liver mitochondria isolated from thirteen-lined ground squirrels. I compared this anoxia effect among animals that were summer active (SA), or during hibernation (in torpor or interbout euthermia; IBE). Anoxia decreased state 3 respiration in all groups, but mitochondria isolated from torpid squirrels were least affected; these decreases paralleled decreased activity of electron transport ...

Overwintering Biology Of The Brown Marmorated Stink Bug, Halyomorpha Halys (Hemiptera: Pentatomidae), John Ciancio

Electronic Thesis and Dissertation Repository

The invasive crop pest Halyomorpha halys has been established in Ontario since 2012 and poses a significant threat to Canadian agriculture. I investigated the tolerance of H. halys to three stressors - low temperatures, desiccation, and energy depletion - in addition to investigating the role of lab-induced diapause in enhancing stress tolerance. Overwintering H. halys depress their supercooling point to -15.4 °C and LT₅₀ to -17.5 °C after acute (1 h) exposure, however they do not encounter these temperatures while overwintering indoors. Moreover, overwintering H. halys maintain their water balance through a reduction of water loss rates, while conserving ...

Measuring The Impact Of A Weeklong Fall Break On Stress Physiology In First Year Engineering Students, Ayesha Khan, Heather Poole, Elliott A. Beaton

The Canadian Journal for the Scholarship of Teaching and Learning

Canadian post-secondary institutions are increasingly introducing a fall break into their term calendars, with the stated goal of reducing student stress and improving academic success. We conducted a pilot study around the time of this fall break during which we collected saliva samples to measure the ratio of two metabolic hormones (cortisol and dehydroepiandrosterone (DHEA)) from first-year male engineering students in order to document possible changes in their stress levels before and after the break. Participants self-identified a particular day in the week prior to the break that they considered to be most stressful, followed by a day in the ...

Endothelial Glycocalyx Shedding In Pediatric Diabetic Ketoacidosis, Rufina Ning

Electronic Thesis and Dissertation Repository

Diabetic ketoacidosis (DKA) is a state of severe insulin deficiency resulting in hyperglycemia, ketoacidosis, and inflammation. Children with DKA have an increased risk of microvascular complications (e.g. stroke). The glycocalyx maintains the anti-thrombotic properties of endothelial cells (ECs), however the glycocalyx status is unknown in DKA. We quantified major glycocalyx components: hyaluronic acid (HA), heparan sulfate (HS), chondroitin sulfate (CS), and syndecan-1 in DKA plasma and correlated them with DKA severity. HA/HS were significantly increased in the plasma of DKA patients in comparison to insulin-controlled type-1 diabetics, but only HA correlated to DKA severity. Exogenous addition or removal ...

Characterizing The Cortical Contributions To Working Memory-Guided Obstacle Locomotion, Carmen Wong

Electronic Thesis and Dissertation Repository

While walking in complex environments, the ability to acquire information about objects in our surroundings is essential for successful obstacle negotiation. Furthermore, the ease with which most animals can traverse cluttered terrain while grazing, exploring, or hunting is facilitated by the capacity to store obstacle information in working memory (WM). However, the underlying neural substrates supporting such complex behaviours are poorly understood. Therefore, the goal of this thesis is to examine the neural underpinnings of WM-guided obstacle negotiation in the walking cat.

Obstacle locomotion was studied in two main paradigms, characterized by whether obstacle presence was detected via vision or ...