CAG/CTG repeat instability is associated with at least 14 neurological disorders, including Huntington’s disease and Myotonic dystrophy type 1. In vitro and in vivo studies have showed that CAG/CTG repeats form a stable hairpin that is believed to be the intermediate for repeat expansion and contraction. Addition of extra DNA is essential for repeat expansion, so DNA synthesis is one of the keys for repeat expansion. In vivo studies reveal that 3’ CTG slippage with subsequent hairpin formation (henceforth called the 3’ CTG slippage hairpin) occurs during DNA synthesis. It is proposed that hairpin tolerance machinery is activated because prolonged stalling of DNA polymerase triggers severe DNA damage. As a means toward studying the hairpin-mediated expansion, we created a special hairpin substrate, mimicking the 3’ CTG slippage hairpin, to determine which polymerase promotes hairpin bypass. Our studies reveal polymerase β (pol β) is involved in the initial hairpin synthesis while polymerase δ (pol δ) is responsible for the resumption of DNA synthesis beyond the hairpin (extension step). Surprisingly, we also found that the pol δ can remove the short CTG hairpin by excision of the hairpin with its 3’ to 5’ exonuclease activity. Besides repairing the hairpin directly, resolving the hairpin is an alternative pathway to maintain CAG/CTG repeat stability. With limited understanding of which human helicase is responsible for resolving CAG/CTG hairpins, we conducted a screening approach to identify the human helicase involved. Werner Syndrome Protein (WRN) induces the hairpin repair activity when (CTG)35 hairpin is formed on the template strand. Primer extension assay reveals that WRN stimulates pol δ synthesis on (CAG)35/(CTG)35 template and such induction was still found in the presence of accessory factors. Helicase assay confirms that WRN unwinds CTG hairpin structures. Our studies provide a better understanding of how polymerases and helicases play a role in CAG/CTG repeat instability. Considering CAG/CTG repeat instability associated disorders are still incurable, our studies can provide several potential therapeutic targets for treating and/or preventing CAG/CTG repeat associated disorders.

Exposure of cells to hydrogen peroxide can cause oxidative damage to cellular constituents including lipids, protein, and DNA. At elevated concentrations, hydrogen peroxide can trigger cell death by apoptosis or necrosis. Apoptotic cell death can be prevented by overexpression of the oncoprotein Bcl-2. The exact mechanism by which Bcl-2 blocks cell death is controversial. Some researchers believe that Bcl-2 possesses antioxidant properties that protect cells from apoptosis. The purpose of this thesis was to assess oxidative stress and apoptosis following hydrogen peroxide exposure in Jurkat T cells overexpressing Bcl-2. One of the major objectives was to ascertain whether or not Bcl-2 overexpression elevated the antioxidant capacity of Jurkat T cells to provide protection from oxidant-induced cell death. Hydrogen peroxide treated Jurkat cells became apoptotic at moderate levels of oxidant (25-100 uM H2O2), and necrotic at higher doses (greater than 200 uM H2O2). Bcl-2 overexpression prevented caspase activation and cell death at the apoptotic doses of H2O2, but not the necrotic doses. Caspase inhibition studies demonstrated that Bcl-2 overexpression provided a greater level of resistance from H2O2-induced cell death than the broad-spectrum caspase inhibitor z-VAD.fmk. A systematic study was carried out examining the antioxidant status of Jurkat cells overexpressing Bcl-2. Several Bcl-2 transfectants were utilised for the study, so that any differences seen could be correlated to the level of Bcl-2 expression. Surprisingly, there were no statistically significant differences among the Bcl-2 transfectants for any of the antioxidant enzymes. Jurkat cells overexpressing Bcl-2 exhibited the same level of oxidative damage to lipids and protein in response to H2O2 exposure as the parental Jurkat cells. Interestingly, Jurkat cells overexpressing Bcl-2 continued to grow in culture after H2O2 exposure, despite harboring damage to cellular constituents. Consistent with these results, H2O2 treated Jurkat cells overexpressing Bcl-2, which failed to undergo apoptosis, were more prone to genomic instability. Together, these findings suggest that Bcl-2 overexpression protects Jurkat cells from H2O2-induced cell death by blocking apoptosis. Jurkat cells overexpressing Bcl-2 were no better at detoxifying oxidants and showed the same level of oxidative damage following H2O2 exposure. As a result, the overexpression of Bcl-2 considerably enhanced the mutagenicity of H2O2.

No description available.

No description available.

The subject of this thesis is financial globalisation in historical perspective, and its key contribution is to demonstrate the J-curve as an alternative depiction of financial globalisation since the classical Gold Standard period. As a preliminary and essential step, some definitions and clarifications on globalisation are provided in a literature review. Then, fundamental issues are considered to assess financial globalisation, so that both the goals and the boundaries of the thesis are clearly stated. Throughout the historical period in debate, there were two waves of financial globalisation: the first one occurring during the 1870-1914 period, and the second lasting from the end of the Bretton Woods agreements until the present day. The dominant approach in economics asserts that the degree of commercial and financial integration corresponds over time to a U-shaped pattern, i.e. markets presented high levels of integration during the forty years before WWI. Then, this integration collapsed in the years between the wars, recovering gradually after the Bretton Woods agreements until it reached again in the 1990s the same pre-1914 level of integration. The thesis approaches this model focusing on the financial side. Then, according to the U-curve, contemporary financial globalisation is not unprecedented. This thesis proposes an alternative view. In contrast to the mainstream U-curve, the empirical data provided indicates that today’s financial integration is unprecedented and more pervasive in some key financial markets than it was during the pre-1914 era. The empirical evidence provided proposes that a J-shaped pattern is a more appropriate way to interpret how financial markets have evolved since the late 19th century. The Jshape suggests that in some financial achieved a huge surge from the 1990s to 2005, surpassing the previous level of integration. So, in these markets, contemporary financial globalisation is unprecedented from the 1990s onwards. The J-curve does not mean that all financial markets became more globalised during the late 20th century in comparison to the Gold Standard era, but only some that presented the U-shape from 1870 to 1995. Qualitative aspects of the J-curve are examined. The different institutional frameworks underlying each historical period are discussed revealing that new institutional arrangements, policy changes, technological advances in ICT and a wide range of financial innovations are the key driving forces that have spurred today’s financial globalisation to higher levels than in the past. Finally, the last chapter assesses the key macroeconomic implications of this new era for the world economy.

Chromosome Instability (CIN) is defined as an increase in the rate at which whole chromosomes or large parts are gained or lost. CIN is not only associated with virtually all tumor types, but it is associated with aggressive tumors, tumor recurrence, acquisition of multidrug resistance and poor patient prognosis. However, the genes and molecular defects that contribute to CIN are poorly understood. I hypothesize that KIF11 is an essential gene for chromosomes integrity during mitosis and therefore any defect in KIF11 expression or function will induce CIN and contribute to tumorigenesis. Accordingly, KIF11 was either silenced using siRNA or inhibited using monastrol within two distinct human cell lines and was investigated for CIN associated phenotypes. Here, I have identified and validated KIF11 as a novel CIN gene. This study represents the first steps necessary to identify and develop novel treatments design to target origins of CIN in CIN associated cancers. / February 2017

Assessing hormone receptors (the estrogen and progesterone receptors) and the human epidermal growth factor receptor 2 (HER2) to guide clinical decision making revolutionized treatment for breast cancer patients. However, in the years since these biomarkers were first incorporated into routine clinical care, only a few others have been validated as clinically useful in guiding adjuvant chemotherapy decisions and are recommended by the American Society of Clinical Oncology (ASCO) for patients with hormone-positive breast cancer. For patients with triple-negative breast cancer (TNBC), which lacks hormone and HER2 receptors, not any of these biomarkers are recommended by ASCO due to insufficient evidence that they meaningfully improve clinical outcomes. Breast cancer is the second-leading cause of cancer-related death among women in the US, indicating an unmet need to improve treatments, which can be accomplished in part by identifying and validating novel predictive and prognostic biomarkers that yield actionable information about the clinical course of breast cancers, especially TNBCs. A major obstacle to improving outcomes for breast cancer patients is intratumor heterogeneity (ITH), which can be extensive in breast cancer and drives treatment resistance and relapse. I envision that assaying drivers of ITH can inform clinicians about which breast tumors may be intrinsically more aggressive and carry a greater risk of breast cancer-related morbidity and mortality. My research, presented here, primarily focuses on testing the impact of drivers of ITH (namely, centrosome amplification [CA], the clustering protein KIFC1, and mitotic propensity and its drivers) on clinical outcomes in breast cancer in multivariable models as well as the correlates of in vitro efficacy of centrosome declustering drugs (which can selectively eliminate cancer cells with CA). Collectively, these studies reveal gene signatures and immunohistochemical biomarkers that are independent predictors of aggressive breast cancer course and rational strategies to optimize targeted therapy to combat cancer cells exhibiting CA, thereby contributing to the literature on the development of precision medicine for breast cancer patients, including TNBC patients.

The Richtmyer-Meshkov Instability (RMI) (Commun. Pure Appl. Math 23, 297-319, 1960; Izv. Akad. Nauk. SSSR Maekh. Zhidk. Gaza. 4, 151-157, 1969) occurs due to an impulsive acceleration acting on a perturbed interface between two fluids of different densities. In the experiments presented in this thesis, single mode 3D RMI experiments are performed. An oscillating speaker generates a single mode sinusoidal initial perturbation at an interface of two gases, air and SF6. A Mach 1.19 shock wave accelerates the interface and generates the Richtmyer-Meshkov Instability. Both gases are seeded with propylene glycol particles which are illuminated by an Nd: YLF pulsed laser. Three high-speed video cameras record image sequences of the experiment. Particle Image Velocimetry (PIV) is applied to measure the velocity field. Measurements of the amplitude for both spike and bubble are obtained, from which the growth rate is measured. For both spike and bubble experiments, amplitude and growth rate match the linear stability theory at early time, but fall into a non-linear region with amplitude measurements lying between the modified 3D Sadot et al. model (Phys. Rev. Lett. 80, 1654-1657, 1998) and the Zhang & Sohn model (Phys. Fluids 9. 1106-1124, 1997; Z. Angew. Math Phys 50. 1-46, 1990) at late time. Amplitude and growth rate curves are found to lie above the modified 3D Sadot et al. model and below Zhang & Sohn model for the spike experiments. Conversely, for the bubble experiments, both amplitude and growth rate curves lie above the Zhang & Sohn model, and below the modified 3D Sadot et al. model. Circulation is also calculated using the vorticity and velocity fields from the PIV measurements. The calculated circulation are approximately equal and found to grow with time, a result that differs from the modified Jacobs and Sheeley's circulation model (Phys. Fluids 8, 405-415, 1996).

Das mediale patello-femorale Ligament (MPFL) wurde in den letzten Jahren und Jahrzehnten als maßgeblicher passiver Stabilisator der Kniescheibe identifiziert und in biomechanischen Studien beschrieben. Auch wurden die verschiedenen Möglichkeiten der operativen Rekonstruktion des MPFL und deren klinisches Outcome bei patellofemoraler Instabilität in zahlreichen Studien beschrieben sowie relevante Ergebnisse für den klinischen Alltag formuliert. Ziel dieser Arbeit war es, die MPFL-Ersatzplastik als Revisionseingriff mit dem Outcome bei Primäreingriffen zu vergleichen und Faktoren zu bestimmen, die das klinische Outcome beeinflussen. Hierzu wurden 61 Patienten, die von Januar 2009 bis Dezember 2012 in der Klinik für Unfall- und Wiederherstellungschirurgie des Diakoniekrankenhauses Friederikenstift gGmbH Hannover operativ mittels MPFL-Ersatzplastik stabilisiert worden sind, untersucht. Retrospektiv nach Aktenlage und im Rahmen einer klinischen Nachuntersuchung wurden anhand eines standardisierten Studienprotokolls verschiedene Ausgangs- und Outcome-Parameter erhoben und mittels IBM SPSS Statistics for Windows, Version 20.0. Armonk, NY: IBM Corp. Released 2011 ausgewertet. Es zeigte sich, dass die Patienten der Primärgruppe eine signifikante Verbesserung durch die Operation erzielen konnten, bei den Patienten der Revisionsgruppe traf dies nicht auf alle Parameter zu. Im Vergleich der Ausgangs- und Outcome-Parameter der Primär- und Revisionsgruppe zeigten sich keine signifikanten Unterschiede. Des Weiteren zeigte sich, dass die Ausgangsparameter Alter bei OP, operativ-versorgte Seite, BMI, Beruf, generelle sportliche Betätigung, verwendete Fadenanker zur Transplantatfixierung an der Patella und Lage der Bohrkanäle in der Patella das Outcome der Operation signifikant beeinflussten.

<p>Topoisomerase 1 (Top1), a Type IB topoisomerase, functions to relieve transcription- and replication-associated torsional stress in DNA. Top1 cleaves one strand of DNA, covalently associates with the 3’ end of the nick to form a Top1-cleavage complex (Top1cc), passes the intact strand through the nick and finally re-ligates the broken strand. The chemotherapeutic drug, Camptothecin, intercalates at a Top1cc and prevents the crucial re-ligation reaction that is mediated by Top1, resulting in the conversion of a nick to a toxic double-strand break during DNA replication or the accumulation of Top1cc. This mechanism of action preferentially targets rapidly dividing tumor cells, but can also affect non-tumor cells when patients undergo treatment. Additionally, Top1 is found to be elevated in numerous tumor tissues making it an attractive target for anticancer therapies. We investigated the effects of Top1 on genome stability, effects of persistent Top1-cleavage complexes and elevated Top1 levels, in Saccharomyces cerevisiae. We found that increased levels of the Top1cc resulted in a five- to ten-fold increase in reciprocal crossovers, three- to fifteen fold increase in mutagenesis and greatly increased instability within the rDNA and CUP1 tandem arrays. Increased Top1 levels resulted in a fifteen- to twenty-two fold increase in mutagenesis and increased instability in rDNA locus. These results have important implications for understanding the effects of CPT and elevated Top1 levels as a chemotherapeutic agent.</p> / Dissertation