Medicine and Health Sciences Commons^™

Biochemical Characterization Of Human Mismatch Recognition Proteins Mutsα And Mutsβ, Lei Tian

University of Kentucky Doctoral Dissertations

The integrity of an organism's genome depends on the fidelity of DNA replication and the efficiency of DNA repair. The DNA mismatch repair (MMR) system, which is highly conserved from prokaryotes to eukaryotes, plays an important role in maintaining genome stability by correcting base-base mismatches and insertion/deletion (ID) mispairs generated during DNA replication and other DNA transactions. Mismatch recognition is a critical step in MMR. Two mismatch recognition proteins, MutSα (MSH2-MSH6 heterodimer) and MutSβ (MSH2-MSH3 heterodimer), have been identified in eukaryotic cells. MutSα and MutSβ have partially overlapping functions, with MutSα recognizing primarily base-base mismatches and 1-2 nt ID mispairs …

The Role Of The L-Type Calcium Channel And Its Carboxyl-Terminus, Miranda Jean Byse

University of Kentucky Doctoral Dissertations

In the heart, the primary role of the L-type calcium channel (LTCC) Ca_V1.2 is to conduct calcium into cardiomyocytes and initiate contraction. However, part of the Ca_V1.2 channel itself, the cleaved carboxyl-terminus (CCt) can also localize to the nucleus and regulate gene transcription. Therefore, the goal of this dissertation project was to determine the role and regulation of CCt in the embryonic and adult heart. The global hypothesis of my dissertation project is that CCt localizes to the nucleus in embryonic and adult cardiomyocytes via a calcium-mediated mechanism and regulates transcription. A model of pharmacological LTCC …

Neural Mechanisms Of Sympathetic Activation During Hyperinsulinemia And Obesity-Induced Hypertension, Megan Elyse Bardgett

University of Kentucky Doctoral Dissertations

Obesity afflicts more than 30% of the U.S. population and is a major risk factor for the development of hypertension, type II diabetes, and cardiovascular disease. Studies in humans and animals indicate that obesity is associated with increased sympathetic outflow to the vasculature and kidneys. One mechanism postulated to underlie the increase in sympathetic nerve activity (SNA) in obesity is hyperinsulinemia. Little is known regarding the central circuitry underlying elevated SNA and arterial blood pressure (ABP) during hyperinsulinemia and obesity or if sympathoexcitatory circuits are still responsive to insulin in obesity.

Hyperinsulinemic-euglycemic clamps elevate SNA to the hind limb vasculature …

Explorations In Homeoviscous Adaptation And Mass Spectral Analysis Of Membrane Lipids, Michael Douglas Timmons

University of Kentucky Doctoral Dissertations

The focus of this dissertation is centered on the mass spectral analysis of lipids and changes occurring in keeping with the concept of homeoviscous adaptation [1]. Homeoviscous adaptation is the process of modification of membrane lipids in response to environmental stimuli [1]. Dissertation investigations applied this concept to prokaryotic and eukaryotic organisms, and expanded the perception of environmental factors from exogenous organic solvents to intracellular environment.

The field of lipidomics deals with the analysis of phospholipid and fatty acid components of membranes the changes that occur due to environmental stimuli and their biological significance [2-6]. The high sensitivity of mass …

Studies Of The Effects Of Dopamine Neuron Stimulating Peptides In Rodent Models Of Normal And Dysfunctional Dopaminergic Systems, Joshua Lee Fuqua

University of Kentucky Doctoral Dissertations

A theoretical post-translational processing model of the proprotein form of glial cell line-derived neurotrophic factor (GDNF) likely produces three biologically active peptides. The three prospective peptides formed are 5, 11, and 17 amino acid peptides, entitled dopamine neuron stimulating peptide -5 (DNSP-5), -11 (DNSP-11), and -17 (DNSP-17), respectively. The DNSPs were hypothesized to increase dopaminergic neuron function because of their relationship to GDNF: a molecule with established neurotrophic actions on dopaminergic neurons. The DNSPs have the potential to provide a therapeutic molecule similar to GDNF, but with increased ease of delivery and improved bioavailability.

Neurochemical effects of DNSPs were examined …

Development Of Novel Ahr Antagonists, Hyosung Lee

University of Kentucky Doctoral Dissertations

Aryl hydrocarbon receptor (AHR) is a sensor protein, activated by aromatic chemical species for transcriptionally regulating xenobiotic metabolizing enzymes. AHR is also known to be involved in a variety of pathogenesis such as cancer, diabetes mellitus, cirrhosis, asthma, etc. The AHR signaling induced by xenobiotics has been intensively studied whereas its physiological role in the absence of xenobiotics is poorly understood. Despite a number of ligands of AHR have been reported thus far, further applications are still hampered by the lack of specificity and/or the partially agonistic activity. Thus, a pure AHR antagonist is needed for deciphering the AHR cryptic …

The Radiosensitization Effect Of Parthenolide In Prostate Cancer: Implications For Selective Cancer Killing By Modulation Of Intracellular Redox State, Yulan Sun

University of Kentucky Doctoral Dissertations

Parthenolide (PN), a major active component of the traditional herbal medicine feverfew, has been shown to have anti-inflammatory and anti-tumor properties. More remarkably, the cytotoxicity of PN seems selective to tumor cells but not their normal cell counterparts. In the present study, we investigate whether and how PN selectively enhances tumor sensitivity to radiation therapy by using prostate cancer cells LNCaP, DU145 and PC3, as well as normal prostate epithelial cells PrEC.

Our study demonstrates that inhibition of NF-κB pathway and suppression of its downstream target MnSOD are common mechanisms for the radiosensitization effect of PN in prostate cancer cells. …

Structural Instability Of Human Ribosomal Rna Gene Clusters, Dawn Michelle Stults

University of Kentucky Doctoral Dissertations

The human ribosomal RNA genes are critically important for cell metabolism and viability. They code for the catalytic RNAs which, encased in a housing of more than 80 ribosomal proteins, link together amino acids by peptide bonds to generate all cellular proteins. Because the RNAs are not repeatedly translated, as is the case with messenger RNAs, multiple copies are required. The genes which code for the human ribosomal RNAs (rRNAs) are arranged as clusters of tandemly repeated sequences. Three of four catalytic RNAs are spliced from a single transcript. The genes are located on the short arms of the five …

Local Synaptic Network Interactions In The Dentate Gyrus Of A Cortical Contusion Model Of Posttraumatic Epilepsy, Robert F. Hunt Iii

University of Kentucky Doctoral Dissertations

Posttraumatic epilepsy is a common consequence of brain trauma. However, little is known about how long-term changes in local excitatory and inhibitory synaptic networks contribute to epilepsy after closed-head brain injury. This study adapted a widely used model of experimental brain injury as a mouse model of posttraumatic epilepsy. Behavioral seizure activity and alterations in synaptic circuitry in the dentate gyrus were examined in mice after experimental cortical contusion brain injury. Spontaneous behavioral seizures were observed in 20% of mice after moderate injury and 36-40% of mice weeks after severe injury. In the dentate gyrus, most mice displayed regionally localized …

Function Of Androgen Receptor In Prostate Cancer Epithelial Mesenchymal Transition And Microtubule Targeting, Menglei Zhu

University of Kentucky Doctoral Dissertations

Prostate cancer is the most frequently diagnosed non-skin cancer and the third leading cause of cancer mortality among men in the US. Androgens are functionally required for the normal growth of the prostate gland and play a critical role in prostate tumor development and progression. Epithelial-mesenchymal-transition (EMT) is an important process during normal development, and cancer cell metastasis.

This study examined the ability of androgens to influence EMT of prostate cancer epithelial cells and evaluate the effect of taxol chemotherapy on androgen signaling in prostate cancer cells in prostate cancer. The EMT pattern was evaluated on the basis of expression …

Characterization And Optimization Of Microelectrode Arrays For Glutamate Measurements In The Rat Hippocampus, Pooja Mahendra Talauliker

University of Kentucky Doctoral Dissertations

An overarching goal of the Gerhardt laboratory is the development of an implantable neural device that allows for long-term glutamate recordings in the hippocampus. Proper L-glutamate regulation is essential for hippocampal function, while glutamate dysregulation is implicated in many neurodegenerative diseases. Direct evidence for subregional glutamate regulation is lacking in previous in vivo studies because of limitations in the spatio-temporal resolution of conventional experimental techniques. We used novel enzyme-coated microelectrode arrays (MEAs) for rapid measurements (2Hz) of extracellular glutamate in urethane-anesthetized rats. Potassium-evoked glutamate release was highest in the cornu ammonis 1 (CA1) subregion and lowest in the cornu ammonis …