Pharmacology, Toxicology and Environmental Health Commons^™

Identification Of Early Diagnostic And Predictive Biomarkers Of Cisplatin-Induced Acute Kidney Injury Using Metabolomics, Yong Jin Lim

Electronic Thesis and Dissertation Repository

Cisplatin is an effective chemotherapeutic agent used for the treatment of a wide variety of solid tumors and hematologic cancers. Despite its effectiveness, cisplatin is associated with several toxic effects to non-cancerous tissues. Nephrotoxicity is the main dose-limiting toxicity in cisplatin therapy, manifesting as acute kidney injury (AKI) in approximately one-third of patients receiving cisplatin. AKI is defined as an abrupt decline in kidney function and is associated with several short- and long-term adverse outcomes, including chronic kidney disease, cardiovascular disease, and mortality. AKI is currently diagnosed by increased serum creatinine (SCr) concentrations. However, SCr is a marker of functional …

Antidepressants Versus Placebo For Generalized Anxiety Disorder: A Systematic Review And Meta-Analysis, Katarina Kopcalic

Electronic Thesis and Dissertation Repository

Objectives: To assess the efficacy and acceptability of antidepressants compared to placebo among adults with a primary diagnosis of generalized anxiety disorder (GAD). Methods: Five electronic databases and 2 trial registries were searched to identify studies for inclusion. The risk of bias version 1 tool was used to assess the risk of bias. A random-effects meta-analysis was conducted using RevMan web. Results were presented using forest plots. Results: 38 studies (12,570 participants) were included. Very low-quality evidence showed a benefit for antidepressants over placebo in the rate of treatment response (RR, 1.39: 95% CI: 1.27, 1.52) and no differences in …

Non-Renal Alterations Of Drug Disposition In Chronic Kidney Disease, Nicholas Tonial

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Chronic kidney disease (CKD) results in profound changes to non-renal drug elimination pathways including hepatic drug metabolism and hepatic transport mediated excretion. This results in complex pharmacological changes to drug disposition in the setting of kidney dysfunction. Four million Canadians are affected by CKD and the average CKD patient takes 14 medications daily with up to 40% experiencing adverse drug reactions at some point in their disease progression. Better elucidation of these changes in the setting of CKD is required to properly dose medications to provide therapeutic benefits while minimizing toxicity. This thesis aimed to better understand the impact kidney …

The Effect Of Oatp2b1-Mediated Statin Transport On Beta Cell Dysfunction, Jihoon Kwon

Electronic Thesis and Dissertation Repository

Statins are a class of cholesterol-lowering drugs which work by inhibiting the mevalonate pathway. Statin treatment has been linked to an increase in the risk of new-onset diabetes mellitus, and previous studies have suggested impairment in insulin secretion following statin treatment. Recent work from our laboratory confirmed the expression of organic anion transporting polypeptide 2B1 (OATP2B1), an important statin uptake transporter, in human pancreatic beta cells. Our study examined the role of OATP2B1 in statin-associated beta cell toxicity using INS-1 cells as a beta cell model. We showed that OATP2B1 augments cellular accumulation of rosuvastatin and atorvastatin, but not pravastatin. …

Absence Of Enhancer Of Zeste Homolog 2 Promotes The Progression Of Kras-Driven Pancreatic Ductal Adenocarcinoma, Xiaoyi Wang

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Pancreatic ductal adenocarcinoma (PDAC) is estimated to be the second deadliest cancer by 2030. Previous studies showed constitutive activation of KRAS (KRAS^G12D) is a key genetic driver of PDAC, accelerated by deletion of the epigenetic regulator Enhancer of Zeste Homologue 2 (EZH2). However, contradictory findings suggest multiple roles for EZH2. The goal of this study was to define EZH2’s contributes to early KRAS^G12D-driven PDAC. I hypothesized that EZH2 restricts KRAS^G12D initiation of PDAC in response to injury. To address this hypothesis, genetically modified mice with targeted deletion of the SET domain of Ezh2 +/- KRAS …

Prefrontal Coding Of Naturalistic Working Memory: Mechanisms During Normal Maintenance And Modelled Disease, Megan P. Roussy

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Neural activity in the primate lateral prefrontal cortex (LPFC) has been causally linked to working memory (WM) ⁠— the brief maintenance and mental manipulation of information. Primates use WM to perform tasks in complex contexts; however, neural mechanisms of WM and the pathophysiology related to WM deficits have traditionally been studied using simple tasks that deviate from naturalistic conditions. This raises the question, how is WM processed in naturalistic conditions? To explore this, I trained two macaque monkeys on a spatial WM task set in a naturalistic virtual environment. During the task, a target was presented in 1 of 9 …

Investigating A Novel Receptor That Mediates Vasoconstriction In Mouse Femoral Arteries, Joselia Carlos

Electronic Thesis and Dissertation Repository

The synthetic peptide trans-cinnamoyl-leucine-isoleucine-glycine-arginine-leucine-ornithine-amide (tcLIGRLO) causes smooth muscle contraction in mouse femoral arteries. The identity of the receptor that mediates this response is undetermined. We hypothesize that the novel mechanism for tcLIGRLO-induced contractions involves a G-protein coupled receptor (GPCR) and a G_q-Ca²⁺ signalling pathway. Chapter 2 describes experiments using femoral arteries isolated from male and female systemic protease-activated receptor 2 (PAR2KO) mice (n=31; 21 – 39 weeks of age) using tcLIGRLO and the G_q-inhibitor, YM-254890 (YM). Contractions produced by tcLIGRLO did not differ by sex but decreased as age increased. YM inhibited tcLIGRLO-induced contractions. Chapter …

Exogenous Surfactant As A Delivery Vehicle For Intrapulmonary Therapeutics, Brandon J. Baer

Electronic Thesis and Dissertation Repository

As an organ system, the lung has unique advantages and disadvantages for direct drug delivery. Its contact with the external environment allows for the airways to be easily accessible to intrapulmonary delivery. However, its complex structure, which divides into more narrow airways with each branch, can make direct delivery to the remote alveoli challenging. The objective of this thesis was to overcome this issue by using exogenous surfactant, a lipoprotein complex used to treat neonatal respiratory distress syndrome, as a carrier for pulmonary therapeutics. It was hypothesized that therapeutics administered with a surfactant vehicle would display enhanced delivery to the …

Characterizing The Structural, Biophysical And Functional Effects Of S-Glutathionylation On Stim1 Ca2+ Sensing, Christian Michael Sirko

Electronic Thesis and Dissertation Repository

Stromal interaction molecule 1 (STIM1) is an endo/sarcoplasmic reticulum (ER/SR) calcium (Ca²⁺) sensing protein that initiates cytoplasmic Ca²⁺ influx via store-operated calcium entry (SOCE). STIM1, in conjunction with Orai, a plasma membrane (PM) protein, function as mediators of SOCE through the formation of calcium-release activated calcium (CRAC) channels. S-Glutathionylation of STIM1 at Cys56 has been shown to evoke constitutive Ca²⁺ entry in DT40 cells, however no studies have carefully investigated the biophysical and structural effects of this covalent modification to the luminal domain, which are critical for understanding the molecular mechanism underlying the regulation of …

The Effects Of Maternal Delta-9-Tetrahydrocannabinol And Cannabidiol Exposure On Fetal Heart Development In Mice, Gregory Robinson

Electronic Thesis and Dissertation Repository

Up to 22.6% of pregnant women consume cannabis during pregnancy despite the uncertainty of teratogenicity of the main ingredients in cannabis, delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD). This study tested the hypothesis that gestational THC and CBD exposure leads to heart abnormalities. Daily, oral THC exposure induced heart abnormalities in 68% of offspring with three main phenotypes including thickened semilunar valves, ventricular myocardial hypertrophy and hypoplastic coronary arteries in fetuses, and postnatal cardiac dysfunction. Altered gene expression of key cardiogenic regulators, increased proliferation, and reduced epicardial epithelial-to-mesenchymal-transition were demonstrated implicating potential mechanisms responsible for these abnormalities. Also, maternal CBD exposure resulted …

Molecular Mechanisms Regulating The Platelet Thrombin Receptor Par4, Pierre E. Thibeault

Electronic Thesis and Dissertation Repository

Proteinase activated receptor 4 (PAR4) is a G-protein-coupled receptor with an important role in the platelet response to vascular injury. In platelets, PAR4 activation, by thrombin-cleavage of its N-terminus and unmasking of a tethered ligand, leads to G-protein- and beta-arrestin-mediated intracellular signalling pathways which result in platelet activation, shape change, and ultimately, platelet aggregation. As an important platelet thrombin receptor, PAR4 is an interesting target for the development of anti-platelet therapeutics. However, molecular determinants of PAR4 activation, signalling, and signal regulation remain poorly understood. In this thesis, mechanisms of PAR4 activation and signalling were studied through determination of the molecular …

Understanding Neonicotinoid Related Immunosuppression: A Potential For Beneficial Bacterial Intervention, John A. Chmiel

Electronic Thesis and Dissertation Repository

The use of neonicotinoid pesticides has been implicated in the recent decrease of honey bee (Apis mellifera) populations. In this thesis, a Drosophila melanogaster model was used to characterize immune impairment associated with imidacloprid (neonicotinoid) exposure and test the ability of beneficial bacteria (lactobacilli) to alleviate these harmful effects. The experiments outlined in chapters 2 and 3 demonstrate that imidacloprid alters the gut microbiota by exploiting the cooperation between gut immune pathways. The pesticide reduces expression of Duox via dysregulation of the immune deficiency pathway resulting in decreased hydrogen peroxide production. This contributes to the microbiota changes but …

Excess No Stabilizes The Luminal Domain Of Stim2 In A Cys-Specific Manner Thereby Regulating Basal Calcium Homeostasis And Store-Operated Calcium Entry, Matthew Novello

Electronic Thesis and Dissertation Repository

Stromal-interaction molecule 2 (STIM2) is an endoplasmic reticulum (ER) membrane-inserted Ca²⁺-sensing protein which, together with the plasma membrane Ca²⁺ channel Orai1, regulates basal Ca²⁺ homeostasis and store-operated Ca²⁺ entry (SOCE). Recent evidence suggests that S-nitrosylation, which is the covalent attachment of a nitric oxide (NO) moiety to a cysteine thiol, can attenuate the function of the paralog STIM1 protein. Compared to STIM1, STIM2 also functions as a basal Ca²⁺ homeostatic feedback regulator. Therefore, the objective of my study was to evaluate the susceptibility of STIM2 to S-nitrosylation and the effects that this …

Pregestational Diabetes Induced Congenital Heart Defects And Coronary Artery Malformations; Mechanisms And Preventative Therapies, Anish Engineer

Electronic Thesis and Dissertation Repository

Congenital heart defects (CHDs) arise from perturbations in complex molecular and cellular processes underlying normal embryonic heart development. CHDs are the most common congenital malformation, occurring in 1 to 5% of live births, and are the leading cause of pediatric mortality. Adverse genetic and environmental factors can impede normal cardiogenesis and increase the likelihood of CHDs. Pregestational maternal diabetes increases the risk of CHDs in children by more than four-fold. As the prevalence of diabetes rapidly rises among women of childbearing age, there is a need to investigate the mechanisms and potential preventative strategies for these defects. The aim of …

Maternal Nicotine Exposure Induces Congenital Heart Defects In The Offspring Of Mice, Elizabeth Greco

Electronic Thesis and Dissertation Repository

Congenital heart defects are the most prevalent birth defect, and maternal cigarette smoking is a known risk factor. Nicotine replacement therapies are recommended to pregnant women who smoke to aid in smoking cessation, as this alternative is thought to be much safer compared to cigarette smoking. However, these products contain nicotine, and the safety of nicotine on the developing heart is not well known. In this thesis, a mouse model was used to test the hypothesis that maternal nicotine exposure (MNE) during pregnancy leads to congenital heart defects and coronary artery defects in the offspring of mice. MNE resulted in …

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 best …

Consequences Of Environmental Mercury Exposure For Migratory Fitness And Survival Of Passerine Birds, Yanju Ma

Electronic Thesis and Dissertation Repository

Mercury (Hg) is a global contaminant that persists in the environment. The organic form, methylmercury (MeHg) has been shown to adversely affect bird immune function, foraging behavior, navigation, and flight ability. Many songbirds migrate seasonally, a process that consists of multiple endurance flights and refueling at stopovers. Current knowledge of the effects of MeHg on songbird migration and survival is mostly speculative. In this thesis, I present three studies of MeHg in migratory songbirds. In Chapter 2, I assessed the breeding ground MeHg exposure (inferred from feather Hg) of 15 songbird species captured during fall migration at bird banding stations …

The Role Of Oatp-Mediated Statin Transport In Pancreatic Beta Cell Function, Michelle S. Kim

Electronic Thesis and Dissertation Repository

Cholesterol-lowering statins, or the 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) reductase inhibitors, are one of the leading treatments for hypercholesterolemia and are recognized for their ability to prevent cardiovascular events. Though safe and effective for most, statin therapy has recently been associated with new-onset diabetes, with risk varying depending on potency and dose. Additionally, in vitro data suggest statin-mediated alterations in insulin secretion; however, the exact mechanism is currently unknown. Statins are known substrates of various membrane transporters belonging to the organic anion-transporting polypeptides (OATPs), on which they rely heavily for hepatic uptake and therapeutic efficacy. We have recently reported expression of OATP1B3 …

The Effects Of Acetylenic Tricyclic Bis-(Cyano Enone) On Cell Migration, Eddie Chan

Electronic Thesis and Dissertation Repository

Although cancer survival rates have significantly improved over the past few decades, the improvements are primarily due to early diagnosis and inhibiting cancer growth. Limited progress has been made in the treatment of cancer metastasis, which contributes to 90% of cancer related deaths, and therapeutic agents targeting the various aspects of metastasis are lacking. One potential approach is to utilize small pharmacological compounds to inhibit tumour cell motility, as a strategy against tumour cell migration, invasion, and metastasis. The acetylenic tricyclic bis-(cyano enone), TBE-31, has been shown to be a promising chemopreventative compound. However, its effects on cell migration are …

Microbial Repopulation Following In Situ Star Remediation, Gavin Overbeeke

Electronic Thesis and Dissertation Repository

In situ STAR (Self-sustaining Treatment for Active Remediation) is an emerging remediation technology which uses smouldering combustion to destroy nonaqueous phase liquid (NAPL) contamination in the subsurface. Since STAR smouldering travels through contaminated soils slowly (~0.5 to 5 m/day) and subjects them to high temperatures (400–1000°C), it is expected that this technology will thoroughly dry and sterilize the zones which it treats. Further, soils surrounding the treatment zone which are not smouldered will be heated, although not smouldered, by virtue of their proximity to STAR, impacting microbial communities within them. Therefore, the objectives of this work are to quantify the …

New Insights Into Signal Detection Of The Effects Of Exposures During Pregnancy, Fatma Etwel

Electronic Thesis and Dissertation Repository

There is inadequate information on the fetal safety of drugs during pregnancy for the majority of marketed drugs. It is challenging to examine the safety and efficacy of drugs during pregnancy due to the ethical issues of exposing unborn babies to these chemicals. It often takes many years before associations between a drug and its safety, efficacy, and toxicity in pregnancy can be established. This thesis will examine strategies in signal detection of the effects of drug exposures during pregnancy.

Meta-analyses have become useful in the area of clinical teratology. Observational studies provide the main source of information in these …

Corticotropin Releasing Factor Receptor Type 1 Signaling In Epilepsy And Traumatic Brain Injury, V V Chakravarthi Narla

Electronic Thesis and Dissertation Repository

Stress increases the frequency by which epileptic seizures occur. Corticotropin-releasing factor (CRF) coordinates neuroendocrine, autonomic and behavioral response to stress. This thesis sought to study the cellular and molecular mechanisms by which CRF regulates the activity of neural circuits in the piriform cortex (PC) in normal and epileptic states. The PC is richly innervated by CRF and 5-HT containing axons arising from the central amygdala and raphe nucleus. CRFR₁ and 5-HT_2A/CRs have been shown to interact in a manner where CRFR activation subsequently potentiates the activity of 5-HT_2A/CRs. The first purpose of this thesis was …

Characterization Of The Catalytic Ck2 Subunits With Substitutions At Residues Involved In Inhibitor Binding, Paul Desormeaux

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CK2 is a constitutively active, ubiquitously expressed and pleiotropic serine/threonine protein kinase that is implicated in many cellular functions including tumorigenesis. CK2 has two catalytic subunits, CK2a and CK2a’, that carry out its function in the cell. Previous studies have indicated that inhibitor-refractory mutants have been effective in recovering residual CK2 activity, in the presence of inhibitors, when compared to wild type CK2. Based on these observations, inhibitor-refractory mutants were created for both CK2a and CK2a’ and tested with various concentrations with two CK2-specific inhibitors, CX-4945 and inhibitor VIII. The CK2a triple mutant (V66A/I174A/H160D) was tested in inducible U2OS Flp-In …

Beta Blocker Dialyzability And Effectiveness In Chronic Hemodialysis Patients, Alvin Tieu

Electronic Thesis and Dissertation Repository

Of the minimal information describing drug dialyzability, the majority was obtained prior to modern hemodialysis membranes. This study characterized the dialyzability of the most commonly prescribed beta blockers in patients undergoing high-flux hemodialysis. Eight subjects were recruited to a pharmacokinetic, 4-way crossover trial. Drug concentrations were measured using mass spectrometry and dialyzability determined by the arterial-venous difference and recovery clearance methods. A provincial-wide retrospective cohort study was designed to determine the effect of dialyzability on adverse clinical outcomes. Beta blocker efficacy can be hindered if substantial clearance occurs during dialysis. Our results demonstrate atenolol and metoprolol are extensively cleared during …

Evaluating The Role Of Intestinal Transporters In Fruit Juice-Drug Interactions, Mandy Mj Li

Electronic Thesis and Dissertation Repository

Fruit juice-drug interactions (FJDIs) involving non-metabolized oral medications result in decreased drug exposure that may lead to reduced therapeutic efficacy. The effect is thought to be mediated by inhibition of the intestinal drug transporters organic anion transporting polypeptide 1A2 and 2B1 (OATP1A2 and OATP2B1) by fruit juice constituents, however the exact mechanisms remain controversial. We tested the hypothesis that fruit juices limit the absorption of fexofenadine through interactions with specific intestinal transporters. In vitro transport and fruit juice inhibition studies using fexofenadine, a medication involved in FJDIs, revealed that in addition to previously implicated transporters, organic cation transporter 1 (OCT1) …

Mitigation Of Pesticide Toxicity By Food-Grade Lactobacilli, Mark E. Trinder

Electronic Thesis and Dissertation Repository

Lactobacilli are Gram-positive bacteria used in fermented foods. Many species are commensal microbiota members that confer host benefits. This thesis investigated lactobacilli mitigation of organophosphate and neonicotinoid pesticide toxicity in mammals and insects, respectively. Lactobacillus rhamnosus GG (LGG) and GR-1 (LGR-1) were found to sequester, but not metabolize, organophosphate pesticides (parathion and chlorpyrifos) in solution. For LGG, this sequestration reduced organophosphate pesticide absorption in a Caco-2 intestinal Transwell model and promoted survival of Drosophila melanogaster lethally exposed to chlorpyrifos. Supplementation of mice with LGR-1 was found to alter host xenobiotic metabolism in the liver, and consequently chlorpyrifos metabolism following acute …

Investigating The Suitability Of The Crayfish Metabolome As A Bioindicator Of Stream Conditions, Natalie M. Izral

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The suitability of the crayfish metabolome as a bioindicator of stream conditions was investigated because there is a need for fast responding, sensitive, diagnostic, and ecologically relevant bioindicators. A laboratory study assessed Procambarus clarkii metabolome sensitivity to six different treatments of food or DO stress. A field study in subcatchments of the Red River Valley, Manitoba, Canada assessed the effects of land-use type (reference, agriculture, wastewater effluent) on the Orconectes virilis metabolome. Crayfish were sacrificed, and hepatopancreas, gill, and tail tissues were dissected. Analyses found the metabolome was sensitive enough to potentially diagnose food and DO stress in P. clarkii …

Cardioprotective Role Of The Cholinergic System, Mouhamed Dakroub

Electronic Thesis and Dissertation Repository

The process of aging is an irreversible continuum experienced by all individuals. A large number of physiological transformations occur to the cardiovascular system as one ages. These changes result in increased risk of developing cardiovascular diseases, many of which are frequently seen in geriatric populations. While the exact mechanisms of age-related cardiac dysfunction have not been established, abnormal cholinergic dysfunction has been implicated in the pathology of other age related diseases; therefore, we have hypothesized that age induced cholinergic dysfunction is detrimental to cardiac function and health. This study seeks to identify whether increased cholinergic signaling, either by transgenic overexpression …

Regulation Of Hepatic Drug Metabolizing Enzymes In Chronic Kidney Disease, Thomas J. Velenosi

Electronic Thesis and Dissertation Repository

Chronic kidney disease (CKD) occurs as a result of declining renal function for 3 or more months. CKD effects 1 in 10 Canadians and is associated with a number of co-morbidities including diabetes and cardiovascular disease. To manage CKD and associated co-morbidities, patients take an average of 12 medications with a median pill burden of 19. Indeed, renal drug elimination is compromised in CKD, as declining glomerular filtration reduces drug excretion into urine. More recently, studies have provided evidence of altered non-renal drug clearance in CKD. The majority of drug clearance occurs in the liver by CYP2C and CYP3A drug …