The objective of the investigations described in this thesis was to characterize the in vivo pharmacological and PK-PD properties of buprenorphine relative to fentanyl with respect to: 1) kinetics... Show moreThe objective of the investigations described in this thesis was to characterize the in vivo pharmacological and PK-PD properties of buprenorphine relative to fentanyl with respect to: 1) kinetics of onset and offset of the pharmacological effects at the mu-opioid receptor, 2) selectivity of action (antinociception versus respiratory depression), 3) the interspecies extrapolation of the PK-PD correlation of the antinociceptive and respiratory depressant effect, 4) the role of active metabolites, 5) kinetics of antagonism of the respiratory depressant effect. Preclinical investigations were performed to develop and validate mechanism-based PK-PD models for the effects of opioids on antinociception and respiration. These PK-PD models were subsequently applied to characterize the effects of buprenorphine and fentanyl in humans. It was shown that the developed PK-PD model can be used to predict the efficacy and safety outcome of opioids in animals. Furthermore, the PK-PD model had excellent properties to enable animal-to-human extrapolation of the efficacy and safety outcome. Show less
Atherosclerosis is a progressive disease of the large arteries characterized by lipid deposition, inflammation, cell death and fibrosis and it is the major cause of death in the Western world. In... Show moreAtherosclerosis is a progressive disease of the large arteries characterized by lipid deposition, inflammation, cell death and fibrosis and it is the major cause of death in the Western world. In this thesis new and experimental therapies against atherosclerosis are designed and tested. New targets for these therapies were identified by using a mouse model for atherosclerosis, the LDL receptor deficient mouse. We used micro-arrays to compare gene expression from mice with atherosclerosis to control mice and the following targets, all related to leukocyte migration and activation, were identified; CCR5, CXCR3, CD99, IL-16, OX-40 and CD127. Vaccines against CD99, IL-16 and CD127 were designed and tested. Specific antagonists of CCR5 and CXCR3 were used to block these molecules and a specific antibody against OX40 ligand was tested in LDL receptor deficient mice. The effects of these treatment strategies are described in the chapters of this thesis. In conclusion, modulation of leukocyte activation and migration provides an attractive possibility for future drug design in the field of atherosclerosis. Show less
With the use of combinatorial phage display, solid phase peptide synthesis and a multidiscipline of molecular and cellular assays in vascular biology, the research described in this thesis has... Show moreWith the use of combinatorial phage display, solid phase peptide synthesis and a multidiscipline of molecular and cellular assays in vascular biology, the research described in this thesis has resulted in the identification of two novel peptides targeting to SR-AI and CD40 respectively which hold promise as targeted contrast agents for the diagnosis of atherosclerosis symptom. In addition, a peptide named VIVIT and its derivatives had been discovered and synthesized which constitute a more selective and less toxic drug candidate than currently used immunosuppressant cyclosporine A or FK506, leading to new generation immunosuppressants and therapeutics for autoimmune diseases such as rheumatoid arthritis or allograft transplantation and cardiovascular disorders including atherosclerosis, restenosis and cardiac hypertrophy. Show less
Our kidneys play a major role in regulating the body__s internal environment, via transportation of water, salt, potassium and waste products. As a result of this transport function, cells within... Show moreOur kidneys play a major role in regulating the body__s internal environment, via transportation of water, salt, potassium and waste products. As a result of this transport function, cells within the kidney are relatively sensitive to injury. This injury can occur when the kidneys are exposed to anticancer drugs, antibiotics, toxic chemicals or as a result of a drop in blood flow during kidney transplantation (ischemia/reperfusion injury). As a consequence, renal function is rapidly lost. The primary targets for injury are epithelial cells lining the proximal tubule. These cells rest on a basement membrane via cell-matrix interactions and are connected to each other via cell-cell interactions. At these adhesion sites, several signalling complexes are located, which are linked to the F-actin cytoskeleton of the cell. When cells are damaged, they alter or may loose their cell-cell and cell-matrix adhesions in association with reorganization of the actin cytoskeleton. This is associated with changes in the activation status of several signal transduction pathways. The research described in this thesis was designed to identify __new__ signalling pathways involved in renal cell injury and understand their role in this process. The changes in protein expression and phosphorylation that occur in association with changes in cell adhesion and cytoskeletal organization prior to or during renal cell injury were analyzed using 2D-Difference In Gel Electrophoresis (DIGE) and 2D-phosphotyrosine blotting.the protein identifications that are described in this thesis point to a more common observation of alterations in the F-actin cytoskeleton that take place during the process of renal cell injury and regeneration. Assessing the precise role of these proteins and their phosphorylation status will increase our understanding of the events that take place during this process. Show less
The main objective of the investigations was to explore the PK/PD correlations of fluvoxamine, as a prototype for the Selective Serotonin Reuptake Inhibitors (SSRIs). In the various investigations,... Show moreThe main objective of the investigations was to explore the PK/PD correlations of fluvoxamine, as a prototype for the Selective Serotonin Reuptake Inhibitors (SSRIs). In the various investigations, a spectrum of different biomarkers was used, each reflecting a specific process on the causal path between drug administration and response. The effects of fluvoxamine have been explored in six investigation steps; from the relatively simple description of the pharmacokinetics of fluvoxamine in plasma and brain to the more complex relationships with the effects on SERT occupancy, 5-HT and 5-HIAA levels and REM sleep. In the PCA study, a categorical PK/PD model was proposed for the effects of fluvoxamine on PCA induced behavioral effects as a kind of intermediary biomarker. There appeared to be important aspects in the PK/PD relationships of fluvoxamine, which was already indicated in the well-known delayed therapeutic effect of SSRIs. The cascading PK/PD model enables the prediction of the effects of functional adaptation upon long-term administration. For SSRIs, adaptation may occur at various levels in the biological system. The various studied biomarkers provide a basis to determine at which level of the biological system functional adaptation occurs (i.e. target site distribution, target expression, turnover of neurotransmitters, transduction mechanisms). Show less
The objective of the investigations described in this thesis was the development of novel PK-PD modelling for the characterisation and prediction of the effects of anti-migraine drugs in clinical... Show moreThe objective of the investigations described in this thesis was the development of novel PK-PD modelling for the characterisation and prediction of the effects of anti-migraine drugs in clinical investigations. The Markov approach has first been applied to migraine data by Hassani and Ebutt. They used a two-state approach that distinguished between headache and no headache. This approach is appropriate for describing the pain free response, but not the pain relief response, as this endpoint would require that an additional state be included. Moreover, this model does not consider a relationship between drug concentration and transition rate. Rather, dose was used as a predictor of pain resolution. Markov models and other state-space models have always enjoyed much appeal in the analysis of disease progression. However, they have seen little application in PK-PD modelling. The current series of studies attempts to evaluate the usefulness of Markov models in determining the PK-PD relationships of 5-HT1B/1D receptor agonists. Show less
In order to form a distant metastasis, a cancer cell has to migrate out of the primary tumor, intravasate into a blood or a lymphatic vessel, subsequently survive in the absence of cell-cell and... Show moreIn order to form a distant metastasis, a cancer cell has to migrate out of the primary tumor, intravasate into a blood or a lymphatic vessel, subsequently survive in the absence of cell-cell and cell-matrix interactions, extravasate the blood or lymphatic vessel, migrate through the target organ and finally proliferate to grow out into a full metastasis. During all of these processes, specific kinases are involved in the concerted activation of distinct signaling pathways. We hypothesised that the protein tyrosine kinase FAK plays a crucial role in one or multiple of the processes involved in the formation of metastases. Therefore, the overall aim of the studies described in this thesis was to investigate the role of the non-receptor protein tyrosine kinase FAK in the distinct processes involved in tumorigenesis and metastasis and to unravel the involved downstream signaling pathways. Moreover, the potential of a combined therapy of the inhibition of FAK and exposure to the cytostatic doxorubicin was tested, as well as dissection of the intracellular events downstream of FAK. Show less
