Exchange–spring systems have been proposed as one method of addressing the media trilemma, where a balance must be maintained between thermal stability, writeability and signal to noise ratio. High anisotropy films coupled to low anisotropy films, in bit patterned media (BPM), via the exchange interaction allow the reversal mechanism to be tailored such that thermal stability is maintained whilst the switching field remains realisable in terms of available write elements. Understanding how the exchange interaction is mediated by through exchange break layers (EBL) is key in successfully creating an optimal exchange spring structure based on Co/Pd thin films for applications such as BPM.The work presented in this thesis shows that the perpendicular magnetic anisotropy (PMA) ofCo/Pd magnetic multilayers can be tuned by varying the Ar ion energy during deposition, usingremote plasma sputtering. This provides a novel method of tailoring the PMA without affecting the film composition and reduces the need for post fabrication processing. It is demonstrated that the reduction in PMA is due to chemical intermixing at the multilayer interface as the Ar ion energy is increased. This provides a method of creating two phase or graded exchange–spring materials for data storage or spin torque applications. In–situ anisotropy tuning was used to create hard and soft magnetic phases using Co/Pd multilayers to explore the effect of an exchange break layer (EBL) on exchange coupling. The relative coupling was investigated using Pd and Ta as the exchange break layer in two–phase anisotropy systems. The exchange–spring effect was found to extend 4 nm in the case of a Pd, whereas in the case of a Ta EBL only a 0.5 nm layer exhibited the same effect. These results highlight the importance of the choice of material for the EBL on the effective performance of the exchange–spring.

Parkinson’s disease (PD) impairs the quality of life of patients and causes substantial social and economic burden. However the currently available symptomatic treatments, although initially effective, do not satisfactorily control the progressive disability experienced by patients with PD in the long run. In order to develop effective treatments for patients that aim to attain the desired effect with as few adverse events as possible, it is crucial to be able to follow and understand the biological mechanisms underlying the continued neural degeneration and treatment failure. The efforts to understand the precise pathway by which neurodegenerative processes proceed and the development of approaches to modulate them offers the promise to eventually enable the prevention of these neurodegenerative diseases. This dissertation focused on two potential synthetic methods to produce pharmaceutical grade Fluorodopa, ultimately to be able to produce positron emitting 18Fluorodopa in South Africa with its potential for studying neuronal mechanisms in the brain. 18Fluorodopa allows a unique almost non-invasive in vivo approach to the evaluation of neurochemical function in the human brain and its local introduction will be a valuable addition to medical research within South Africa’s borders. The successful implementation of safe and efficient non-radioactive models for Fluorodopa synthesis was achieved. The successful demonstration of locally synthesised Fluorodopa safety, as well as a low toxicity profile, both in vitro using cell cultures and in vivo in mouse models was achieved. These were both positive outcomes of objectives set out for this study. Copyright / Dissertation (MSc)--University of Pretoria, 2010. / Pharmacology / unrestricted

In underground construction grouting is performed to seal tunnels and caverns against excessive water inflow or to reduce the lowering of the ground water table. The rheological properties, such as viscosity and yield stress, of the used grouts play a fundamental role in grouting. No method has been developed yet to measure these properties in-line in the field during grouting. Methods used today are rather primitive and not robust enough for field use and they are mainly performed in order to verify and fulfil stipulated quality criteria. Modern grouting rigs are today equipped with continuous measurement of flow and pressure but instruments for continuous monitoring of rheological properties and their changes with time in the field are still lacking. A relatively new method, known as ‘UVP-PD’, for continuous in-line measurements of the rheological properties of cement grouts, was tested in this work. Standard grouting equipment (UNIGROUT) and flow meter (LOGAC) was used to ensure field conditions. The objective of this work was to determine the feasibility of the ‘UVP-PD’ method for cement based grouts. After performing full scale experimental works, this method was found feasible for measuring the rheological properties of cement based grouts directly in-line.

Tim-3 and PD-1 are powerful immunoinhibitory molecules involved in immune tolerance, autoimmune responses, and antitumor or antiviral immune evasion. A current model for Tim-3 regulation during immune responses suggests a divergent function, such that Tim-3 acts synergistically with TLR signaling pathways in innate immune cells to promote inflammation, yet the same molecule terminates Th1 immunity in adaptive immune cells. To better understand how Tim-3 might be functioning in innate immune responses, we examined the kinetics of Tim-3 expression in human CD14 + M/M 4 in relation to expression of IL-12, a key cytokine in the transition of innate to adaptive immunity. Here, we show that Tim-3 is constitutively expressed on unstimulated peripheral blood CD14 + monocytes but decreases rapidly upon TLR stimulation. Conversely, IL-12 expression is low in these cells but increases rapidly in CD14 + M/M.J, in correlation with the decrease in Tim-3. Blocking Tim-3 signaling or silencing Tim-3 expression led to a significant increase in TLR-mediated IL-12 production, as well as a decrease in activation-induced up-regula-tion of the immunoinhibitor, PD-1; TNF-a production was not altered significantly, but IL-10 production was increased. These results suggest that Tim-3 has a role as a regulator of pro- and anti-inflammatory innate immune responses.

PD-1 (Programmed Cell death protein -1) est un récepteur co-inhibiteur exprimé à la surface de lymphocytes T (LT) activés. Ce récepteur joue un rôle important dans le maintien de la tolérance périphérique tout en protégeant contre les maladies auto-immunes et inflammatoires. Cependant, une expression élevée et permanente de PD-1 et ses ligands PD-L1 et PD-L2 (PD-Ls) perturbe la réponse immunitaire contre les pathogènes et les cellules tumorales. Les inhibiteurs de points de contrôle immunitaires (ICI) ciblant l'axe PD-1/PD-Ls représentent aujourd’hui une avancé majeure dans le traitement de différents types de cancer, tant sur le plan de l’efficacité que de la tolérance. Le nivolumab (nivo) et le pembrolizumab (pembro) sont deux anticorps monoclonaux (AcM) anti-PD-1 qui bloquent l’interaction de PD-1 avec ses ligands. Ces AcM ont montré des résultats prometteurs dans le traitement de multiples types de cancers comme le mélanome, le cancer bronchique non à petites cellules, le carcinome à cellules rénales, etc. Malgré l’importance thérapeutique de nivo et de pembro dans le cancer, aucune étude n’a défini le devenir de PD-1 après la liaison à ces deux AcM. L’objectif de cette étude a été donc d’évaluer l’endocytose de PD-1 suite au liaison à des AcM anti-PD-1 (clone J110, nivo, pembro) et de déterminer s’il y a différence entre nivo et pembro vis à vis leur capacités à induire l'internalisation de PD-1. L’étude de l’endocytose de PD-1 a été réalisé sur des LT humains obtenus à partir du sang périphérique de donneurs sains et activés avec des Ac anti-CD3/anti-CD28 ou concanavaline A afin d’exprimer le récepteur PD-1. L’analyse des données par cytométrie en flux a montré que l’engagement de PD-1 avec l’Ac anti-PD-1 (clone J110) induit son endocytose dans les LT humains et que 50% de la totalité de PD-1 de surface est internalisé dans les premiers 30 minutes suivant l’incubation de cellules à 37°C, suivi d’un taux d’endocytose plus lent (56% en 60min). Notre étude a montré également que la liaison de nivo et de pembro au PD-1 induit son endocytose et que la plupart de récepteur est internalisée dans les 30 min suivant l’incubation de cellules à 37°C. Toutefois, 32 à 50% des récepteurs sont résistants à l’endocytose. L’analyse comparative de nivo et de pembro a révélé une différence statistiquement significative (p=0.03) entre le taux d’internalisation du complexe PD-1/nivo et celui du PD-1/pembro (46% versus 25% en 30min, respectivement). Même à des concentrations élevées de pembro, la liaison de nivo induit une meilleure internalisation de PD-1, ce qui suggère que nivo pourrait être plus efficace. Bien que les ICI comme nivo et pembro sont connus de bloquer l’interaction de PD-1 avec ses ligands, PD-L1 et PD-L2, notre étude a montré pour la première fois que ce deux AcM induisent aussi l’endocytose du récepteur PD-1 dans les LT humains avec des taux différents, et que 32% à 50% de récepteurs PD-1 sont résistants à l’endocytose. Ces résultats pourraient être exploités pour améliorer l’internalisation de PD-1 dans les LT humains et par la suite augmenter les potentiels thérapeutiques de nivolumab et de pembrolizumab dans le traitement du cancer. Mots clés : Récepteur PD-1, Ligands de PD-1, Lymphocytes T, Inhibiteurs de point de contrôle immunitaires, Anticorps anti-PD-1, Nivolumab, Pembrolizumab, Endocytose, Cancer / PD-1 (Programmed Cell death protein -1) is a co-inhibitory receptor expressed on the surface of activated T cells. It plays an important role in maintaining peripheral tolerance and protecting against autoimmune and inflammatory diseases. However, permanent expression of PD-1 and its ligands PD-L1/ PD-L2 (PD-Ls) disrupts the immune response against pathogens and tumor cells. Immune checkpoint blockade (ICB) targeting the PD-1/PD-Ls axis has revolutionized the treatment of many cancers. Nivolumab (nivo) and pembrolizumab (pembro) are two anti-PD-1 monoclonal antibodies (mAb) that block the interaction between PD-1 and its ligands. They have shown promising results in the treatment of multiple types of cancers such as melanoma, non-small cell lung cancer, renal cell carcinoma, etc. Surprisingly, despite the success of anti-PD-1 in cancer immunotherapy, no-one has defined the destiny of surface PD-1 following antibody binding. Therefore, the objective of my master thesis was to define the fate of surface PD-1 following antibody binding and whether different anti-PD-1 Abs in the clinic differ in their ability to induce PD-1 endocytosis. The study of PD-1 endocytosis was performed on human T lymphocytes obtained from peripheral blood of healthy donors and activated with anti-CD3/anti-CD28 Ab or concanavalin A to express PD-1 receptor. Data analysis by flow cytometry showed that following anti-PD-1 Ab binding, 50% of PD-1 becomes endocytosed by 30min. In addition, we found that the PD-1 receptor is internalised upon its engagement with nivo and pembro and that most of the receptor is endocytosed within 30 min. However, 32 to 50% of the receptors are resistant to endocytosis. The comparative analysis of nivo and pembro has revealed a statistically significant difference (p=0.03) between the internalisation rate of the PD-1/nivo complex versus PD-1/pembro (46% versus 25% by 30min, respectively). Even at high concentrations of pembro, nivo induces better internalization of PD-1, suggesting that nivo could be more effective than pembro. Our study showed for the first time that ICB involves not only in the blockade of PD-1/PD-Ls interaction, but also in the endocytosis of PD-1 receptors from the surface of human T-cells, which differs between nivolumab and pembrolizumab. These results could be exploited to increase the therapeutic potential of nivolumab and pembrolizumab in cancer treatment. Keywords: PD-1 receptor, PD-1 ligands, T lymphocytes, Immune checkpoint blockade, Anti-PD1 antibodies, Nivolumab, Pembrolizumab, Endocytosis, Cancer

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第17813号 / 医博第3811号 / 新制||医||999(附属図書館) / 30628 / 京都大学大学院医学研究科医学専攻 / (主査)教授 髙折 晃史, 教授 武藤 学, 教授 杉田 昌彦 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第19594号 / 医博第4101号 / 新制||医||1014(附属図書館) / 32630 / 京都大学大学院医学研究科医学専攻 / (主査)教授 竹内 理, 教授 河本 宏, 教授 朝長 啓造 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第20254号 / 医博第4213号 / 新制||医||1020(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 武藤 学, 教授 川上 浩司, 教授 生田 宏一 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第21637号 / 医博第4443号 / 新制||医||1034(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 河本 宏, 教授 松田 道行, 教授 小川 誠司 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第21681号 / 医博第4487号 / 新制||医||1036(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 松田 文彦, 教授 清水 章, 教授 濵﨑 洋子 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM