Zugl.: München, University, Diss., 2009.

Tierärztl. Hochsch., Diss., 2003--Hannover.

Cancer is the most fatal disease after cardiovascular disease with over 8.2 million deaths worldwide each year. Ever since the serendipitous discovery of mustard gas as an anti-cancer therapeutic in the 1940s, serious efforts have been put into discovering more chemotherapies. Chemotherapies can be categorized into different groups such as alkylating agents (cisplatin, cyclophosphamide), antimetabolites (5-fluorouracil, Ara-C) and mitotic inhibitors (taxanes, vinca alkoids) among others. While chemotherapies have proven to kill cancer cells by targeting cell division processes, over time, tumor cells can adapt and become resistant to these drugs. With a growing understanding of cell signaling networks, targeted therapies are being developed to overcome the issue of chemotherapy resistance. Targeted therapies are highly specific molecules that bind to a specific cellular protein or molecule and block signaling networks associated with biological processes. One of the most frequently dysregulated receptor systems in cancers is the receptor tyrosine kinase family with ErbB being one of the most studied receptors families. ErbB or HER receptors consists of four structurally related receptor tyrosine kinases namely, EGFR/ErbB1, HER2/ErbB2, HER3/ErbB3 and HER4/ErbB4. The ErbB family of receptors plays a major role in morphogenesis of the human body as well as various cellular responses such as cell growth, differentiation and proliferation. Overexpression and dysregulation of these receptors, particularly EGFR and HER2, have been linked to a number of cancers such as breast cancer, gastric cancer, ovarian cancer and non-small cell lung cancer, to name a few. One of the most successful therapies against ErbB related cancers have been targeted therapies. Targeted therapies for ErbB related cancers are of two kinds: (i) Small molecule tyrosine kinase inhibitors (such as erlotinib and gefitinib against EGFR) and, (ii) Monoclonal antibodies (such as trastuzumab against HER2 and cetuximab against EGFR). These drugs function either by inhibiting the kinase activity of the receptor and preventing phosophorylation of tyrosine residues, or binding to some other site on the extracellular domain of the receptor and preventing ligand binding and heterodimerization of ErbB monomers. These drugs have proven to have limited efficacy as monotherapy, but are more effective in combination with standard chemotherapies. However, tumor cells can adapt their signaling networks developing resistance to targeted therapies over the course of treatment and lead to cancer progression. While overexpression and dysfunction of EGFR and HER2 are implicated in most ErbB driven cancers, recent studies have found HER3 playing a pivotal role in inducing resistance to EGFR and HER2 targeted therapies in various cancers and has been found to be the most sensitive node in driving the PI3K pathway leading to tumorigenesis. Thus, there is an urgent need to develop drugs targeted against HER3 and bring them into the clinic. Since HER3 lacks kinase activity, only monoclonal antibodies can be developed against it. Currently, there are a number of molecules in clinical development that target HER3. For example, patritumab and MM-121 are humanized monoclonal antibodies that target the extracellular domain of HER3 receptor and leads to inhibition of HER3-PI3K signaling followed by rapid internalization of the receptor. MM-111 and MM-141, two different bispecific monoclonal antibodies that bind to HER2, HER3 and IGFR-1, HER3, respectively, are currently in clinical development. HER3 inhibitors provide hope to effectively overcome HER3 induced tumor resistance and successfully treat several ErbB driven cancers. However, further development of HER3 inhibitors is necessary by taking strategic approaches. One of these approaches it the utilization of systems biology, a branch of biology that involves computational and mathematical modeling of complex biological systems with the aim of discovering emergent properties of biological systems. Systems biology enables researchers to get a deeper understanding of biological networks such as that of ErbB and make predictive models and test outcomes. This approach was used by Merrimack Pharmaceuticals to develop novel monoclonal antibodies against HER3. Computational outcomes were successfully validated by in vitro and in vivo experiments. Thus, this suggests that systems biology might be the future of designing and developing HER3 inhibitors that would successfully overcome HER3 resistance and cancer progression.

La bonne prise en charge des tumeurs repose sur un diagnostic précoce et une thérapie ciblée efficace. Nousétudions dans ce projet trois outils théranostiques, différents par leur origine et par leurs caractéristiques, afin dedémontrer leur intérêt pour l’imagerie et la thérapie des tumeurs.Le premier est un outil biologique, les cellules souches mésenchymateuses humaines connues pour leur tropismenaturel pour les sites inflammatoires et/ou hypoxiques, qui devrait donc leur permettre d’atteindre les tumeurs.Le deuxième outil consiste en des nanoparticules fonctionnalisées ou non avec un ligand ciblant les cellulestumorales, délivrées sous forme de spray dans les poumons. Cette méthode présente l’avantage de développer unoutil peu invasif pouvant être administré chez un patient présentant un cancer du poumon disséminé.Le dernier est un outil synthétique, bien défini structurellement, synthétisable de manière reproductible, de petitetaille, qui, après une administration par voie systémique cible les cellules tumorales primaires ou métastasées.Mes travaux permettent de mettre en évidence que, bien que les cellules souches mésenchymateuses ne soientpas de bons vecteurs pour le diagnostic et pour véhiculer un agent vers la tumeur, elles permettent de normaliserla vascularisation tumorale et de réorganiser les flux sanguins au sein de la tumeur. Ceci présente un éventuelintérêt thérapeutique, bien que complexe à mettre en application, qui pourrait ouvrir la porte à un pré-traitement« normalisateur » de la vascularisation tumorale.L’étude sur les nanovecteurs aérosolisés montre qu’ils peuvent être utiles, non seulement pour le ciblage tumoralpassif mais également pour le ciblage actif lorsqu’ils sont greffés avec un anticorps monoclonal spécifique descellules tumorales puisqu’ils permettent de détecter des nodules tumoraux répartis dans les poumons. De plus, leCetuximab utilisé ici comme agent de ciblage acquiert des propriétés nouvelles lorsqu’il est présenté sur desnanoparticules et permettrait de diminuer la résistance des cellules tumorales au traitement.Enfin, la petite molécule synthsétique PoroCombo que nous développons à partir de nos travaux antérieurs sur levecteur RAFT-RGD semble être la plus appropriée des trois pour délivrer une drogue dans le cytoplasme descellules après injection par voie systémique. De plus, cette molécule présente une triple activité anti-tumoraleavec l’induction de la mort cellulaire ainsi qu’un effet anti-angiogénique et le possible déclenchement d’uneréaction immunitaire anti-tumorale.Les trois « biovecteurs » étudiés ouvrent la porte vers un grand nombre d’applications permettant d’améliorer laprise en charge des tumeurs. / A good tumor treatment relies on an early diagnosis and an efficient targeted therapy.Three theranostic tools are studied, each one having a different origin and different properties, in order to showtheir interest for tumor’s imaging and therapy.The first tool is a biologic one, human mesenchymal stem cells (MSC) having a natural tropism towardinflammatory and/or hypoxic sites, which should permit them to reach tumors.The second one is nanoparticles, functionnalized or not with an antibody targeting tumor cells, delivered by alung spray. By this method we develop a non-invasive tool to treat patients with a disseminated lung tumor.The last one is a synthetic small sized theranostic tool with a reproducible synthesis, which, after a systemicadministration, targets primary and metastatic tumor cells.By my work, I show that even if MSC are not good vectors for diagnosis and delivery of therapeutic agents tothe tumors’ sites, they normalize tumors’ vessels, improving blood flow inside the tumor. This property presentsa real therapeutic interest, by pre-treating tumors before using chemotherapy.The study of aerosolized nanovectors reveals their interest for passive tumor targeting and for an active onewhen grafted with a specific monoclonal antibody as they permit the detection of tumor nodules disseminated inthe lungs.More, the targeting agent Cetuximab acquires new properties when grafted on nanoparticles permitting todecrease tumor cells resistance to the treatment.Finally, the small synthetic molecule PoroCombo developed from our previous work on RAFT-RGD vectors,seems to be the most appropriated to deliver a molecule in the cell’s cytoplasm after a systemic administration.This molecule has three anti-tumor activities by inducing cell death, by inducing anti-angiogenic impact and bytriggering anti-tumor immune reaction.The three studied “biovectors” reveal large applications to improve tumors’ treatment.Key words:

Les protéines Sémaphorines et leurs récepteurs Plexines jouent un rôle primordial dans le réseau de signalisation cellulaire. Initialement découvertes pour leur rôle dans le guidage axonal, il fut rapidement mis en lumière qu'elles étaient également impliquées dans le développement du système cardiovasculaire, dans la tumorigénèse et le fonctionnement du système immunitaire, démontrant les multiples facettes de ces protéines. Parmi ces couples de ligands et de récepteurs, la Sémaphorine 3E et son récepteur Plexine D1 représentent des cibles d'intérêt pour les thérapies anti-cancéreuses. La Sémaphorine 3E est surexprimée dans de nombreux cancers et son expression est corrélée à la dissémination métastatique et à la progression tumorale. Ces travaux de thèse ont donc consisté en la caractérisation de ce couple en temps que nouvelle cible anti-tumorale et le développement d'une thérapie ciblée qui a montré des effets prometteurs dans les études pré-cliniques en combinaison avec d'autres thérapies innovantes / The Semaphorin proteins and their receptors Plexins play a primordial role in the cell signaling network. Initially discovered for their role in axonal guidance, it was soon identified that they also are implied in cardiovascular system development, tumorigenesis and immune system functioning, demonstrating the multiple facets of these proteins. Among these pairs of ligands and receptors, Semaphorin 3E and its receptor Plexin D1 represent targets of interest for anticancer therapies. Semaphorin 3E is overexpressed in many cancers and its expression is correlated with metastatic dissemination and tumor progression. This work consisted in characterizing Sema3E/PlxnD1 as new anti-tumor target and developing a targeted therapy. Combination between this therapy and other innovative drugs provided promising results in preclinical studies

The goal of this dissertation was to examine the realized value of targeted therapies in routine care and to identify opportunities for improving the return on medical spending for these technologies. Chapter 1 investigated the value of targeted therapies in lung cancer patients who were treated in routine care. This observational, claims-based analysis used propensity score, and instrumental variable methods, combined with a Kaplan Meier Sample Average estimator to calculate lifetime costs and life expectancy. An incremental comparison showed that the realized value of targeted therapies in routine care was unfavorable relative to chemotherapy treatment. Subgroup analyses revealed that initial erlotinib therapy yielded effectiveness results that are substantially lower than efficacy survival outcomes in molecularly guided trials. Our results indicated that in routine care, chemotherapy was the most cost effective strategy. The unexpectedly low outcomes with first-line erlotinib suggested that some of the value of this treatment was not being realized in practice. Chapter 2 examined the practice patterns of targeted therapies and utilization of predictive biomarker testing in routine care to better understand the observed gaps between trial-based and `real-world' outcomes with these agents. In our nationally representative cohort of lung cancer patients, we found that the vast majority of patients did not undergo molecular testing to inform first-line therapy. Our prediction models for biomarker screening and first-line treatment suggested that phenotypic enrichment criteria guided selection for testing and initiation of erlotinib therapy. Since clinical characteristics do not adequately discriminate between mutation positive and wild type tumors, these practices signal the need for wider dissemination of biomarker screening to accurately target patients towards improving therapeutic gains with erlotinib. Chapter 3 assessed the cost-effectiveness of multiplexed predictive biomarker screening to inform treatment decisions in lung cancer patients. Using a micro-simulation model to evaluate the incremental value of molecularly guided therapy compared to chemotherapy in unselected patients, we found that personalized therapy is a cost effective strategy. Our results indicated that better value of targeted therapies in lung cancer is achievable through molecularly guided treatment.

Violence in South Africa is not only prevalent in society and the home environment, but is also present in the workplace. Although substantial research has been conducted into school violence and learner-focused, school-based violence, the study set out to determine the nature and extent of workplace violence that educators face; identify the effects and consequences of workplace violence on victims; profile educators as victims of workplace violence with specific reference to gender, age and occupational level; and determine the presence and role of policies and educator participation in managing and preventing educator-targeted violence. The comparative investigation further established difference in such experiences between private and public secondary schools. In pursuit of the objectives of the study, 274 self-administered questionnaires were delivered to three public and three private secondary schools in Gauteng after both probability and non-probability sampling methods were employed. A total of 122 completed questionnaires were returned. Using descriptive and inferential data analysis, by means of the Mann-Whitney U test and the Kruskal-Wallis H test, relationships, differences and similarities were determined. Both univariate and bivariate data are displayed in multiple formats. Evident from the results and corroborating existing literature, educators in the study reported having experienced both physical and non-physical (verbal and social) violence, although the survey findings indicate the latter to be dominant. Notably, educators are victimised by various perpetrators and the opportunity to become victimised is greatest during classes, especially in public schools. Educator-targeted violence appears to be the result of multiple interrelated contextual factors that result in a fear for personal safety and far-reaching personal and professional consequences for educators. The profile of educators as victims verified and further exposed various risk factors in terms of demographics and background. Female educators, unmarried educators, public school educators, educators working for long periods of time and educators with lower educational achievements presented greater risk of victimisation. Similarly, female educators and public school educators experienced deficits in power and control. In terms of the public and private divide, significant associations indicated that educators in public schools were more likely to experience physical violence, verbal violence, bullying and vandalism by learners thus justifying their increased likelihood of feeling threatened in the workplace, considering their school at high risk of violence, and viewing workplace violence as a serious problem. Furthermore, with a higher chance of victimisation by not being heard, favouritism and overcrowding, public school respondents were more likely to report lower levels of involvement in decision-making regarding school issues, which consequently affected their sense of power and control in the workplace and increased their risk of victimisation. The majority of respondents indicated having neither been provided with material(s) related to workplace violence nor having received training with regards to the phenomenon (in particular female respondents) therefore the researcher recommends, amongst others, an increase in training and the dissemination of information regarding workplace violence against educators, both in the school setting and among the community. / Dissertation (MSW)--University of Pretoria, 2017. / Social Work and Criminology / MSW / Unrestricted

This thesis discusses the possibilities of using cluster analysis methods for customer segmentation. The theoretical part is focused on description of selected methods of cluster analysis and explanation of other concepts related to this topic, such as CRM, segmentation and targeted communication. In the practical part are applied cluster analysis methods to real data unnamed company with the aim of creating a default substrates useful for planning and implementation of targeted communication. For the main calculations is used program R, for data and output editing is used MS Excel. At the end of the work are evaluated applied methods and summarized lessons learned from the cluster analysis. For a company were created and characterized databases which could be useful for marketing decisions.

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>Magister Scientiae - MSc / Alzheimer’s Disease (AD) is a neurodegenerative disease which results from the irreversible loss of neurons in the brain. The disease is characterized by progressive cognitive impairment with recurrent short-term memory loss. AD is the leading cause of dementia and 4th leading cause of death in the elderly. Success in the treatment of AD has been limited, with drugs only treating it at a symptomatic level due to its pathology being complex and poorly understood. However, it is known that the cholinesterase and MAO-B enzymes play an important role in the disease through their association with production of amyloid plaques and oxidative stress respectively, two mechanisms associated with cell death and the symptoms seen in AD.