Life Sciences Commons^™

Application Of Cytotoxicity Assays For Detection Of Potentially Harmful Bioactive Compounds Produced By Freshwater Bloom-Forming Algae, Jace Thomas Mclaughlin

Electronic Thesis and Dissertation Repository

Detection of harmful bioactive compounds produced by bloom-forming pelagic algae is important to assess the potential risks to communities. We applied two cell-based assays, an erythrocyte lysis assay (ELA) that assesses membrane integrity, and a RTgill-W1 cytotoxicity assay (RCA) that detects changes in cell metabolism, to evaluate the cytotoxic effects of: (1) individual toxins and noxious compounds; and (2) complex mixtures of compounds produced by cyanobacteria and chrysophyte isolates. ELA was insensitive to toxins and noxious compounds except at exceptionally high concentrations (EC₅₀≥10⁶ nM). RCA was sensitive to noxious compounds only, at concentrations greater than reported environmental …

The Role Of Drug Transporters In Statin-Induced Myopathy, Michael J. Knauer

Electronic Thesis and Dissertation Repository

Statins are the first line therapy for treatment and prevention of cardiovascular disease. The 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors, or statins, reduce plasma cholesterol levels by inhibiting the rate-limiting step in cholesterol biosynthesis. While statins are well tolerated, up to 15% of patients develop myopathy, manifesting as muscle aches and pain and in rare cases, potentially life-threatening statin-induced rhabdomyolysis. Given that approximately 3 to 4 million Canadians are treated with statins, an estimated 500,000 patients experience associated skeletal muscle side effects that may prevent the continued treatment of hypercholesterolemia. Despite the prevalence of this side effect, little is known regarding …

Intestinal And Hepatic Drug Transporters And Their Role In The Disposition Of Lipid-Lowering Drugs, Ute I. Schwarz

Electronic Thesis and Dissertation Repository

Membrane transporters are widely recognized for their role in drug disposition in humans. Differences in drug concentration among individuals for drugs used to treat cardiovascular diseases, such as statins and ezetimibe, may result from alteration in hepatic and intestinal transporter function due to genetic, clinical or environmental factors, causing variability in drug efficacy or toxicity.

The closely related uptake transporters organic anion-transporting polypeptides OATP1B3 and OATP1B1, are expressed in human liver sharing numerous drug substrates, including 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors, or statins. Recently, a transport-deficient OATP1B1 variant was associated with increased statin exposure and toxicity, however little is known regarding …

Cadmium Accumulation And Distribution In Lettuce And Barley, Fardausi Akhter

Electronic Thesis and Dissertation Repository

Cadmium (Cd) is a non-essential trace element and its environmental concentrations are increasing due to human activities. Edible plants can accumulate high concentrations of Cd, which could be toxic to humans. Understanding how and where Cd is stored in plants is important for ensuring lower concentration of Cd in the food. In this thesis, the accumulation and distribution of Cd in three agricultural plants, namely lettuce (Lactuca sativa L.), barley (Hordeum vulgare L.) and radish (Raphanus sativus L.), were investigated with a focus on the potential mechanisms involved in the localization of Cd in the root. The …

Human Equilibrative Nucleoside Transporter Subtype 1: Structure-Function Analysis Using Cysteine Mutagenesis And Thiol Modifying Techniques, Jamie Park

Electronic Thesis and Dissertation Repository

Human equilibrative nucleoside transporter 1 is the main mediator of bi-directional nucleoside flux and is found ubiquitously. Inhibitor and substrate interactions with ENT1 are known to be affected by cysteine-modifying reagents. Our aim was to investigate the importance of cysteine residues in hENT1 function and identify which residues were sensitive to thiol modification for further application of cysteine scanning mutagenesis on extracellular loop 5. Transporter function was assessed by the binding of [³H]NBMPR and the cellular uptake of [³H]2-chloroadenosine. Treatment of hENT1 with the neutral sulfhydryl-modifier methyl methanethiosulfonate (MMTS) enhanced [³H]NBMPR binding but decreased …

Statin Transport By Hepatic Organic Anion-Transporting Polypeptides (Oatps), Marianne K. Degorter

Electronic Thesis and Dissertation Repository

Drug transport proteins are important determinants of drug absorption, tissue accumulation, and elimination from the body, and there is growing appreciation for the contribution of altered drug transporter function to interindividual variability in drug response. The organic anion-transporting polypeptides (OATPs/SLCO) are uptake transporters with broad substrate specificity. Notably, the 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors, or statins, are commonly prescribed OATP substrates.

The OATP1B subfamily, expressed predominantly in the liver, is of particular importance to statins, which require hepatic entry to exert their low-density lipoprotein cholesterol lowering effect. We aimed to identify molecular determinants of substrate specificity in the …

The Role Of Grk2 In Hypertension And Regulation Of Gpr30, Bonan Liu

Electronic Thesis and Dissertation Repository

In the hypertensive state, the expression of G protein-coupled receptor kinase 2 (GRK2) level is elevated. On the other hand, the expression of GPR30, a recently discovered GPCR is greatly impaired. The current study focuses on investigating the roles of these two proteins in regulating G protein signaling under the normal and hypertensive states. Angiotensin II and vasopressin were used to examine the effects of GRK2 on G_q coupled GPCR signaling. ERK phosphorylation was proportionally enhanced with GRK2 over-expression. On the other hand, using arborization and wrinkle assays, I have shown that GRK2 acts as a negative regulator of …

Characterization Of Eif2be And Its Interaction With Rgs2, William H. Xue

Electronic Thesis and Dissertation Repository

RGS2 is a GTPase accelerating protein for Gαq and its expression can be upregulated in response to different types of stress. We recently showed that RGS2 can bind to the translation initiation factor, eIF2Bε, and decrease global protein synthesis. The objective of this study is to characterize the RGS2 binding domain of eIF2Bε, and investigate the functional consequences as a result of their interaction. To identify the RGS2 binding domain of eIF2Bε, I generated various truncated eIF2Be-GST fusion proteins and used them in an in vitro pulldown assay. The results of my study revealed that the binding domain lies within …