In part 1 of the thesis quantitative proteomics was used to determine changes in abundance and phosphorylation status of host proteins during infection with the human pathogen chikungunya virus ... Show moreIn part 1 of the thesis quantitative proteomics was used to determine changes in abundance and phosphorylation status of host proteins during infection with the human pathogen chikungunya virus (CHIKV). Several proteins were identified that may be specifically downregulated during CHIKV infection to create a suitable environment for viral replication. eEF2 was identified as a factor that becomes strongly phosphorylated during infection with several viruses which may be a mechanism to stall translation in response to viral infection. In part 2 of the thesis the discovery of a novel and unusual -2/-1 programmed ribosomal frameshifting (PRF) mechanism is described that is used during translation of the nonstructural open reading frame of the economically important porcine reproductive and respiratory syndrome virus (PRRSV). This mechanism relies on a slippery site and stimulatory RNA signal in the PRRSV genome and is stimulated by the viral protein nsp1beta and host poly (C) binding proteins 1 and 2. Frameshifting results in the synthesis of two previously unidentified proteins, nsp2 TF (-2 PRF) and nsp2N (-1 PRF). Virus mutants that can no longer make the frameshift products are attenuated and may be used for vaccine development. Show less
The glycosylation, the reaction which forms a bond between sugar molecules (the donor and the acceptor), is the central reaction in carbohydrate chemistry. Despite tremendous advances in... Show more The glycosylation, the reaction which forms a bond between sugar molecules (the donor and the acceptor), is the central reaction in carbohydrate chemistry. Despite tremendous advances in the past decades, however, the glycosylation reaction remains relatively poorly understood. Especially the formation of 1,2-cis glycosidic linkages remains a significant challenge. This thesis describes an investigation of the influence of reactivity and selectivity of several classes of carbohydrate donors and –acceptors on the selectivity in glycosylation reactions. Special emphasis was placed on the influence of protecting groups on the donor, and nucleophilicity of the acceptor, two major factors that play a tremendous role in the outcome of a glycosylation reaction. The obtained knowledge has been applied in the synthesis of complex carbohydrate molecules, native to pathogens such as Staphylococcus aureus, of which antibiotic-resistant forms such as MRSA present significant danger in hospitals, and the parasite Schistosoma mansoni, causative agent of the neglected tropical disease schistosomiasis. The synthesis of these molecules can play a part in the development of vaccines targeted against these pathogens. Show less
This thesis is part of a project which attempts to unveil the structure of the galactic bulge of our galaxy through the study of the kinematics of stars in low foreground extinction windows.Thus,... Show moreThis thesis is part of a project which attempts to unveil the structure of the galactic bulge of our galaxy through the study of the kinematics of stars in low foreground extinction windows.Thus, in order to effectively constraint the phase-space distribution function of the galactic bulge, we have collected a large number of radial velocities (~3200) and proper motions (~50000) in six of those ``windows'' with low extinction across the bulge. In addition, a self-consistent Schwarzschild model to study the distribution of stellar orbits in the galactic bulge has been produced. Show less
3D Active Shape Modeling is a technique to capture shape information from a training set containing characteristic shapes of, e.g., a heart. The description contains a mean shape, and shape... Show more3D Active Shape Modeling is a technique to capture shape information from a training set containing characteristic shapes of, e.g., a heart. The description contains a mean shape, and shape variations (e.g. eigen deformations and eigen values). Many models based on these statistics, and used for medical purposes, are limited in their application by properties of the training set. These properties are, the radiological modality used for image acquisition (1), the orientation of the images (2), and the density of the data (3). In our model of the cardiac left ventricle, the limits above were relieved by not training on gray level information (1,2), using a Fuzzy Inference System for finding image features in CT and MR data (1), and weighted propagation of image features along the model surfaces (3). Evalutation of our model on both CT and MR showed almost equal performance. Evaluation of three different point-correspondences used for model- building did not clearly indicate one as best. By extended tuning using a grid-computing approach, and propagation of image features, we managed to achieve segmentation results on sparse data comparable to those of others on dense data. Our model is more widely applicable thanks to these developments. Show less
The aim of this thesis was to gain evidence-based insights to improve anatomical and surgical education by evaluating how various levels of visual-spatial abilities interacts with learning using... Show moreThe aim of this thesis was to gain evidence-based insights to improve anatomical and surgical education by evaluating how various levels of visual-spatial abilities interacts with learning using stereoscopic 3D visualization technology Show less
Dutch-type cerebral amyloid angiopathy (D-CAA) is a rare neurodegenerative/neurovascular disease caused by a point mutation in the amyloid precursor protein (APP) gene that leads to aggregation of... Show moreDutch-type cerebral amyloid angiopathy (D-CAA) is a rare neurodegenerative/neurovascular disease caused by a point mutation in the amyloid precursor protein (APP) gene that leads to aggregation of the amyloid beta peptide in the brain vasculature. It is characterized by intracerebral hemorrhages, infarcts, cognitive decline and vascular dementia. To date there are no therapies that prevent or delay D-CAA onset or progression. In this thesis we aimed to model the disease using patient-derived cell models, develop and test an RNA-targeting therapy and look into the mutated protein trafficking in the cell. Using D-CAA patient-derived induced pluripotent stem cells as template, we generated state-of-the-art 3D brain organoids and successfully modeled the amyloid beta aggregation and other D-CAA disease signatures, also found in the D-CAA human brain. We developed and tested an RNA-targeting therapy that showed efficient and significant reduction of the amyloid beta peptide in D-CAA patient-derived cells and control mice. Finally, when looking into the mutated APP protein trafficking we have found that the Dutch mutation affects the processing and trafficking of APP protein prior to the generation of the amyloid beta fragment, a phenotype that was reversed when the RNA-targeting therapy was applied. With the data generated in this thesis we hope to further advance the knowledge on D-CAA disease mechanisms as well as the possibility for therapeutics that will benefit D-CAA patients. Show less
The thesis assess the robustness of 4D flow MRI for analyzing aortic hemodynamics and valvular flow, as well as exploring the clinical potential of this technique in patients with aortic and... Show moreThe thesis assess the robustness of 4D flow MRI for analyzing aortic hemodynamics and valvular flow, as well as exploring the clinical potential of this technique in patients with aortic and valvular disease. The first part of the thesis evaluates the reproducibility of segmenting the aortic lumen and calculating various hemodynamic parameters, demonstrating that these processes can be performed accurately and consistently. The second part examines the natural course of aortic hemodynamics during aging, concluding that hemodynamic parameters remain relatively stable. Furthermore, different hemodynamic phenotypes are identified in patients with aortic root and ascending aortic dilatation, possibly explaining the presence of dilatation. Show less
Improving implant longevity is an eminent challenge in joint replacement surgery with aseptic loosening as the major reason for early failure necessitating revision surgery in both total hip and... Show moreImproving implant longevity is an eminent challenge in joint replacement surgery with aseptic loosening as the major reason for early failure necessitating revision surgery in both total hip and total knee arthroplasty (THA and TKA). Analysis of implant fixation by measuring migration with roentgen stereophotogrammetric analysis (RSA) has shown that the loosening process starts at very early onset after implantation. Implants showing relative high migration during the first post-operative year are prone to failure and subsequent revision later on. However, it is still not crystallized how specific implant characteristics or the surgical procedure affect the implant migration pattern and what degree of initial migration is acceptable without jeopardizing longevity of implant fixation at 10-20 years. In this thesis the migration pattern in relation to longevity of both cemented and cementless stems in THA, the influence of mobile-bearings in TKA on migration and survival, and methods to instantly evaluate implant fixation by inducible displacement have been studied. Show less
Colorectal cancer (CRC) is a complicated disease in which both genetic pre-desposition and environmental factors are important. Patients with inflammatory bowel disease (IBD) have an increased risk... Show moreColorectal cancer (CRC) is a complicated disease in which both genetic pre-desposition and environmental factors are important. Patients with inflammatory bowel disease (IBD) have an increased risk of developing CRC, and it is believed that treatment of IBD patients with 5-Aminosalicylic acid (5-ASA) reduces the CRC risk. The general purpose of the studies described in this thesis was to evaluate the effect of 5-ASA on the development of CRC, as well as determining the feasibility of introducing 5-ASA as an adjuvant therapy for CRC patients. Animal research showed that chronic 5-ASA medication has the ability to prevent colitis-associated CRC, confirming results from 5-ASA medication in IBD patients. Although 5-ASA was not able to prevent the development of sporadic CRC, 5-ASA treatment was found to hold a great promise for the treatment of CRC, by exerting CRC growth inhibiting, anti-progression and cell death inducing effects, and should be considered to be implemented in a future treatment strategy to CRC. Besides this, the determination of cell death products in the circulation of CRC patients and within the tumour, holds a great promise for selection of CRC patient treatment and patient folluw-up. Show less
The most massive galaxies in the local universe are not forming new stars -- but we don__t know why. As a step towards figuring out why big galaxies stop forming stars, we set out to measure when... Show moreThe most massive galaxies in the local universe are not forming new stars -- but we don__t know why. As a step towards figuring out why big galaxies stop forming stars, we set out to measure when they stop forming stars. By looking at the colors of massive galaxies have changed over 10 billion years of cosmic time (roughly 80% of the history of the universe), we found that around 1/6 massive galaxies had already finished their star formation when the universe was just a few billion years old, and around 1/2 were still forming stars about 7 billion years ago. But the story doesn__t stop there. Even after galaxies have stopped forming stars they somehow keep growing in size: the massive, quiescent galaxies that existed 10 billion years ago are 3-10 times more compact than the ones we see today. We confirmed this fact by showing that there really are no galaxies in the local universe as small as those that existed 10 billion years ago. A major feature of this work is detailed and systematic study of the importance of different kinds of errors in these results. In this way, our results are more robust than those that have come before. Show less
Several associations between 14-3-3 proteins and members of the p53 family have been revealed. However, numerous questions regarding 14-3-3 proteins, p53 family members and the relationships... Show moreSeveral associations between 14-3-3 proteins and members of the p53 family have been revealed. However, numerous questions regarding 14-3-3 proteins, p53 family members and the relationships between thetwo families remain. This thesis contributes to answer these questions. Downregulation of 14-3-3_ increased the propensity for DNA-damage induced apoptosis and increased cell-cell contacts, two characteristics that are often lost in cancer cells. Differences between 14-3-3_ and 14-3-3_ in nucleocytoplasmic shuttling have been described. The difference innucleocytoplasmic shuttling likely forms a basis for specialized biological functions of the 14-3-3 isoforms. Keratinocyte specific p53 regulated G2cell-cycle arrest and the lack of a contribution for 14-3-3_ in this cell-type has been observed, whereas 14-3-3_ induction clearly plays a distinct role in G2 arrest in other cell-types. An improved method for detecting p53 induced apoptosis by flow cytometry is portrayed by expressing a duplicated GFP protein. This double GFP protein can be used for future research in the fields of 14-3-3 and p53. A widely used method to detect and quantify p73 splice-variant expression is critically assessed. It turns out that, using this method it is not possible to accurately quantify p73splice-variants. Show less
14q32 microRNAs are known to play a role in various forms of vascular remodelling. This thesis elucidated that snoRNAs of the 14q32 locus are also involved in vascular remodelling processes. The... Show more14q32 microRNAs are known to play a role in various forms of vascular remodelling. This thesis elucidated that snoRNAs of the 14q32 locus are also involved in vascular remodelling processes. The expression of both noncoding RNA types in the human vasculature has been found to be vascular location and vessel type specific and are therefore promising targets for future implementation in clinical practice.The second part of this thesis focuses on three different types of 14q32 microRNA expression regulation in order to affect various vascular remodelling processes. 14q32 DNA methylation, myostatin and CIRBP were tested for their effect on 14q32 microRNA expression and the (subsequent) effect on vein graft disease and tissue ischemia, restenosis and angiogenesis, respectively. DNA methylation is not correlated with 14q32 microRNA expression, but directly interacts with vascular remodelling process status. Myostatin negatively affects 14q32 microRNA expression in vascular smooth muscle cells, but not in inflammatory cells involved in restenosis. Due to this latter finding, overall restenosis was not inhibited by myostatin. Inhibition of CIRBP inhibited 14q32 microRNA expression post-transcriptionally and therefore increased in vitro angiogenesis. These promising findings provide novel indirect regulators of vascular remodelling processes and future research will elucidate the potential for clinical application. Show less
The human body is colonized by microorganisms, collectively referred to as the human microbiota. Microbiota disturbance has been associated with a wide range of diseases and is the focus of many... Show moreThe human body is colonized by microorganisms, collectively referred to as the human microbiota. Microbiota disturbance has been associated with a wide range of diseases and is the focus of many research initiatives. The most widely used approach is based on sequencing of the 16S rRNA gene. This method can also be very valuable for clinical microbiology as it enables identification of a theoretically unlimited number of bacteria present in a specimen and permits (semi)quantitative information about the composition of a microbial community. In this thesis we investigated whether 16S rRNA gene profiling would have added value for direct diagnostics and/or as an indirect tool for evaluating cheaper diagnostic tests or evaluating treatments. The studies in this thesis were focused on respiratory tract infections, bacterial vaginosis, atopic dermatitis or male genital lichen sclerosus. The main challenge of 16S rRNA gene profiling is the clinical interpretation of relative abundance of the identified bacteria in clinical specimens. More clinical studies with appropriate control groups are needed to define and validate clinically relevant cut-off values, to measure microbiota variability over time and to determine microbial phenotypes. The clinical value of 16S rRNA gene profiling will probably become clear in the forthcoming years. Show less
We studied the impact of advances in the development of AF devices on the incidence of complications. More specifically, the safety of the improved non-irrigated catheter (PVAC-Gold) was... Show moreWe studied the impact of advances in the development of AF devices on the incidence of complications. More specifically, the safety of the improved non-irrigated catheter (PVAC-Gold) was investigated. The first generation of this catheter showed a high incidence of asymptomatic cerebral embolism. Subsequently, the ablation device and protocol were revised to improve the safety of this device. Therefore, we investigated whether these revisions improved the incidence of cerebral infarcts by comparing it in a randomized fashion with an irrigated catheter. Secondly, the cryoballoon ablation catheter, was investigated to prevent complications by optimizing the ablation duration. The development of the second-generation cryoballoon brought a significant improvement in terms of efficacy. To prevent complications however, the ablation duration still needed to be optimized. We aimed to optimize the ablation duration by randomizing patients to different ablation durations using the incidence of dormant conduction as an indicator for incomplete isolation. Furthermore we tried to predict the absence of incomplete cryoballoon applications, making the standard waiting period after ablation unnecessary. Finaly, we focused on posterior left atrial box isolation in patients with progressive left atrium illness and investigated the effect of the ablation surface area on the outcome of the ablation. Show less
Democratie van onderaf: het is even verleidelijk als problematisch. Dat zien we niet alleen bij de Occupy-beweging en de Arabische lente, maar ook in de geschiedenis. In 1848 trok een golf van... Show moreDemocratie van onderaf: het is even verleidelijk als problematisch. Dat zien we niet alleen bij de Occupy-beweging en de Arabische lente, maar ook in de geschiedenis. In 1848 trok een golf van revoluties over ons continent. Plotseling kregen miljoenen Europeanen de kans hun stem te laten horen in drukbezochte volksvergaderingen en politieke clubs. In dit moment van gekte leek even alles mogelijk. De toekomst lag open. 1848 – Clubkoorts en revolutie neemt de lezer mee naar de onrustige steden Parijs en Berlijn, twee brandpunten van de ‘Europese lente’. Geerten Waling schetst de dromen en verwachtingen achter de honderden democratische experimenten die er een nieuw publiek debat creëerden. En de politieke realiteit waarmee zij werden geconfronteerd. De revoluties van 1848 werden uiteindelijk allemaal neergeslagen of doofden uit, maar de ervaringen van dat jaar zouden de politieke cultuur in Europa blijvend veranderen. Ze maakten de moderne democratieën mogelijk die wij tegenwoordig als vanzelfsprekend beschouwen. Show less
School refusal is an attendance problem characterized by a young person’s difficulty in going to school, accompanied by emotional distress on the part of the young person and parental attempts to... Show moreSchool refusal is an attendance problem characterized by a young person’s difficulty in going to school, accompanied by emotional distress on the part of the young person and parental attempts to return the young person to regular school attendance. Prolonged absence from school has serious short- and long-term consequences for young people, their families, and schools. Therefore, effective treatment of school refusal is essential. Numerous treatment outcome studies provide evidence for the efficacy of cognitive-behavioural therapy (CBT) for school refusal. Previous research has however indicated that adolescent school refusers may be particularly disturbed and harder to treat. An existing treatment for school-refusing children and adolescents was modified to better account for the impact of developmental variables on engagement in treatment. The studies presented in this dissertation describe the preparation, implementation, and evaluation of the resulting developmentally-appropriate CBT for adolescent school refusal. The treatment was associated with increased school attendance, reduced emotional symptoms, and increased adolescent and parental self-efficacy. Exploratory analyses revealed that several developmental factors were related to treatment outcomes, namely clinician developmental appropriateness, insight, and autonomy. Recommendations for research and clinical practice are made on the basis of these findings, and on the methodological strengths and limitations of the current research. Show less
This study focuses on the decorative oeuvre of Willem Adrianus Fabri (1853-1925). As one of the few decorative painters from the era 1870-1925, quite a bit of his work has been preserved in situ.... Show moreThis study focuses on the decorative oeuvre of Willem Adrianus Fabri (1853-1925). As one of the few decorative painters from the era 1870-1925, quite a bit of his work has been preserved in situ. Characteristic for his decorative paintings is the great variety of activities in terms of interior types. In his almost fifty-year career Fabri has decorated houses, theaters, churches, government buildings, palaces and passenger ships. From around 1877 Fabri worked for the Rotterdam furniture company C.H. Eckhart. This company belonged to the large furniture factories in the Netherlands. Around 1893 Fabri started his own painting studio. Fabri's oeuvre is pre-eminently representative of the profession of decorative painter in the period described. This area of the applied arts in the Netherlands has been neglected so far. Beside the decoration works of Willem Fabri this study examines his network, sources of inspiration, clients and competitors. Show less
