A crucial step of the radiotherapy workflow is the segmentation of the tumors. Currently, this is done manually, which is very time-consuming and therefore puts a lot of burden in the clinical... Show moreA crucial step of the radiotherapy workflow is the segmentation of the tumors. Currently, this is done manually, which is very time-consuming and therefore puts a lot of burden in the clinical workflow. Deep learning techniques, currently state of the art for computer vision tasks, are a potential solution to speed up the process. Even though they have been applied to segment other structures of interest for the RT workflow, they still underperform for the case of tumors. Furthermore, there is limited research in automatic segmentation of tumors for the particular case of MRI, even though this imaging modality presents better soft tissue contrast and it is therefore ideal to visualize tumors. The goal of this thesis was to develop automatic segmentation techniques for tumors on MRI images that deliver clinically acceptable segmentations. The different automatic segmentation methods were applied in two different tasks: the automatic segmentation of the oropharyngeal primary tumor in multiparametric diagnostic MRI images and the automatic segmentation of the cervical cancer gross tumor volume in the MRI images of the brachytherapy treatment images. Show less
This dissertation examines the public presentation of fixed media electroacoustic music and investigates the performative capacities which are involved in materialising such music, in order to shed... Show moreThis dissertation examines the public presentation of fixed media electroacoustic music and investigates the performative capacities which are involved in materialising such music, in order to shed light on the question of what performing means in the context of fixed media music, which is prefabricated and presented through loudspeakers in a concert venue. While electroacoustic music production has been the main focus of academic work in this area in recent decades, less attention has been given to its public presentation. Through the process of composing a series of fixed media works and presenting them in various circumstances, I formulate an understanding of the important elements involved in such process. This has resulted in the emergence of concepts and strategies which ground the composition within its performance context, so that the work comes to full existence only in the performance space. Such perspectives shift the focus from the (alleged) fixity of the medium towards the diversity and wealth of the listening experiences that it can engender. This dissertation also includes an audiovisual part; complementary and of equal importance to the written component, by simultaneously expressing its central ideas and demonstrating them in the form of a multichannel fixed media work. Show less
One of the key discoveries in exoplanet research over the past decade is the abundance of small planets in our Milky Way. Despite their high numbers, our understanding of their atmospheres remains... Show moreOne of the key discoveries in exoplanet research over the past decade is the abundance of small planets in our Milky Way. Despite their high numbers, our understanding of their atmospheres remains limited, and it is unknown if they possess atmospheres at all. Predicting the presence of an atmosphere on small planets is challenging due to factors like atmospheric escape and volcanism. Reliable determination requires direct study of thermal emission, reflected light, or transmission spectrum. With the launch of the JWST in late 2021, we gained unprecedented access to detailed observations of rocky exoplanets, enabling the search for atmospheres composed of carbon dioxide, oxygen, and nitrogen on temperate rocky worlds. My thesis summarizes my work on atmospheric characterization of small, rocky exoplanets using space-based telescopes such as Spitzer, Hubble, and JWST. I have studied a wide temperature range, from lava worlds with atmospheres of outgassed rock vapor at over 2000 Kelvin, to terrestrial planets with temperatures around 400 Kelvin, similar to our inner solar system. I characterized the surfaces and atmospheres of exoplanets like K2-141 b and TRAPPIST-1 c to ultimately learn about their surfaces and the conditions under which rocky planets can retain atmospheres. Show less
Our research focuses on developing advanced nanoparticles for cancer treatment, with a focus on reducing side effects and improving efficacy. We have developed nanoparticles that can not only... Show moreOur research focuses on developing advanced nanoparticles for cancer treatment, with a focus on reducing side effects and improving efficacy. We have developed nanoparticles that can not only target cancer cells but also serve as imaging agents to monitor treatment. In addition, we have investigated how lipids and immune cells in the tumor environment can be manipulated to improve cancer therapy.Our findings show that the developed nanoparticles can improve drug delivery to tumors while reducing side effects to the rest of the body. Moreover, we have shown that lipids can be used to reprogramme immune cells in the tumor environment, causing them to exhibit anti-tumor activity. In addition, the nanoparticles show excellent delivery capabilities in 3D models of skin cancer, allowing them to kill skin tumor cells more effectively.The societal relevance of our research lies in improving cancer treatment options, particularly by reducing side effects and increasing the effectiveness of therapies. These findings provide new insights and approaches for the development of cancer therapies, which can contribute to a better quality of life for patients.We have achieved these results through a multidisciplinary approach using nanotechnology, chemotherapeutic drugs and knowledge of the tumor environment. Our findings are special because they offer promising new strategies for cancer treatment using cutting-edge technologies and insights into tumor biology. Show less
The introduction of the vacuum tube in 1949 revolutionized blood collection, significantly improving sample quality and patient comfort. Over the past 75 years, laboratory diagnostics have evolved... Show moreThe introduction of the vacuum tube in 1949 revolutionized blood collection, significantly improving sample quality and patient comfort. Over the past 75 years, laboratory diagnostics have evolved drastically, from manual to automated processes, reducing required test volumes by over 1,000 times. Despite these advancements, venous blood collection presents logistical challenges, including centralized scheduling and a large volume of biological waste due to the imbalance between the needed blood volume (often very little) and the collected volume (often in excess). The COVID-19 pandemic further emphasized the need for decentralized healthcare solutions and patient empowerment. Capillary blood collection, widely used in point-of-care testing, offers a promising alternative, particularly for patients facing frequently, or difficulties with, venous sampling. The Leiden University Medical Center in the Netherlands experienced a 15 % reduction in volume of laboratory tests during and after the pandemic, attributed to patient preference for local blood collection and testing. To address these challenges, self-sampling devices are emerging, empowering patients and streamlining sample logistics. However, challenges such as cost, transportation regulations, and sample volume adequacy persists. Robust devices tailored for total lab automation and sustainable practices are crucial for widespread adoption. Despite hurdles, the integration of self-sampling into diagnostic processes is inevitable, heralding a shift towards patient-centered, proactive healthcare. Practical recommendations include robust device design, ease of use, affordability, sustainability, sufficient quality and acceptability by seamless integration into laboratory workflows. Although obstacles remain, self-sampling represents the future of laboratory diagnostics, offering convenience, cost-effectiveness, interoperability and patient empowerment. Show less
Spreafico, M.; Hazewinkel, A.-D.; Gelderblom, H.; Fiocco, M. 2024
Oratie uitgesproken door Prof. Dr. Hans Ulrich Scherer bij de aanvaarding van het ambt van hoogleraar Reumatologie aan de Universiteit Leiden op vrijdag 21 juni 2024________________________________... Show moreOratie uitgesproken door Prof. Dr. Hans Ulrich Scherer bij de aanvaarding van het ambt van hoogleraar Reumatologie aan de Universiteit Leiden op vrijdag 21 juni 2024____________________________________________________________Text also in German : Über Barrieren und Brücken: Autoimmunerkrankungen auf dem Weg zur Heilung Show less
The liver X receptor (LXR) is considered a therapeutic target for atherosclerosis treatment, but synthetic LXR agonists generally also cause hepatic steatosis and hypertriglyceridemia. Desmosterol,... Show moreThe liver X receptor (LXR) is considered a therapeutic target for atherosclerosis treatment, but synthetic LXR agonists generally also cause hepatic steatosis and hypertriglyceridemia. Desmosterol, a final intermediate in cholesterol biosynthesis, has been identified as a selective LXR ligand that suppresses inflammation without inducing lipogenesis. Δ24-Dehydrocholesterol reductase (DHCR24) converts desmosterol into cholesterol, and we previously showed that the DHCR24 inhibitor SH42 increases desmosterol to activate LXR and attenuate experimental peritonitis and metabolic dysfunction-associated steatotic liver disease. Here, we aimed to evaluate the effect of SH42 on atherosclerosis development in APOE∗3-Leiden.CETP mice and low-density lipoproteins (LDL) receptor knockout mice, models for lipid- and inflammation-driven atherosclerosis, respectively. In both models, SH42 increased desmosterol without affecting plasma lipids. While reducing liver lipids in APOE∗3-Leiden.CETP mice, and regulating populations of circulating monocytes in LDL receptor knockout mice, SH42 did not attenuate atherosclerosis in either model. Show less
Actinobacteria are well known for the production of bioactive natural products, many of which have applications in the fields of human, animal and plant health. Subject of this thesis are the... Show moreActinobacteria are well known for the production of bioactive natural products, many of which have applications in the fields of human, animal and plant health. Subject of this thesis are the anthracyclines, glycosylated aromatic polyketides with potent anticancer activity. Despite remarkable efficacy against acute leukaemia and various solid tumours, their application is limited by severe side effects, such as cardiotoxicity, therapy-related tumours and infertility.Recent insights into the mode-of-action of anthracyclines have prompted renewed interest into this important class of anticancer compounds. One of the most promising compounds is N,N-dimethyldoxorubicin, which exerts significantly reduced side effects. To date, DMdoxo has not been isolated from natural sources, but biosynthesis would be an attractive option for scaling up production of this promising compound.For this reason, we aimed to engineer the Doxo biosynthetic pathway in S. peucetius for the production of biosynthetic N,N-dimethylated anthracyclines. The challenges that we encountered instigated the study of anthracycline resistance mechanisms in Streptomyces, and potential applications of detoxified anthracyclines as antibiotics. Finally, to facilitate future screening and strain engineering efforts of Streptomyces producer strains, we developed a workflow for integrated quantitative proteomics and metabolomics from small-scale Streptomyces cultures Show less
In this thesis, we aimed to assess outcomes of local disease activity in patients with rheumatoid arthritis (RA) and juvenile idiopathic arthritis (JIA) who received treatment-to-target, and to... Show moreIn this thesis, we aimed to assess outcomes of local disease activity in patients with rheumatoid arthritis (RA) and juvenile idiopathic arthritis (JIA) who received treatment-to-target, and to describe long-term clinical and radiographic outcomes in patients with treated-to-target RA. Show less
Languages frequently make use of spatial vocabulary to describe abstract notions. For instance, the spatial preposition by (‘by the house’) can also describe relations in the temporal and causal... Show moreLanguages frequently make use of spatial vocabulary to describe abstract notions. For instance, the spatial preposition by (‘by the house’) can also describe relations in the temporal and causal domain (‘by Monday’; ‘hit by John’). This dissertation shows that when a spatial term is extended into an abstract domain, some of its spatial meaning persists. Speakers rely on a spatial representation of the abstract domain, which they use to reinterpret the spatial term to obtain an abstract meaning. On the basis of Western European languages, the proposal is formalized for causal prepositions (e.g., French ‘de’ and ‘par’ in passives) as well as demonstratives referring to information content (e.g., the use of English ‘that’ to introduce complement clauses). The proposals are further tested in corpus studies using Biblical Hebrew. Data from the Hebrew Bible additionally show that the analysis can be extended to the use of prepositions for describing social relations. This research shows that spatial meaning often persists when grammaticalization takes place. Use of spatial vocabulary in abstract domains is not metaphorical but deeply embedded in cognition, shaping the conceptualization of abstract relations. In this way, the study of language contributes to our understanding of the human mind. Show less
Tracing the evolution of the molecular gas content in galaxies is critical for a complete understanding of galaxy formation and evolution, as it provides the direct fuel for star formation. Studies... Show moreTracing the evolution of the molecular gas content in galaxies is critical for a complete understanding of galaxy formation and evolution, as it provides the direct fuel for star formation. Studies of high-redshift (z>1) molecular gas reservoirs, most commonly traced by carbon monoxide (CO), have seen substantial growth in recent years thanks to state-of the-art sub-millimeter interferometers such as the Jansky Very Large Array or the Atacama Large Millimeter Array. However, these studies have been largely based on detections of the bright mid/high-J transitions of CO (J>=3), which have been shown to give a biased and incomplete view of the total cold molecular gas content in galaxies. This thesis presents an observational study of the cold interstellar medium of massive galaxies in the distant universe. Chapter 2 presents one of the highest—resolution studies of low-J CO in a high—redshift galaxy to-date, allowing us to map its total cold gas reservoir in unprecedented detail. Chapter 3 presents a survey targeting low-J CO emission in high-redshift unobscured quasar hosts, finding direct evidence for high gas fractions but very short depletion times. Chapter 4 introduces first results from the VLA Legacy Library of Molecular Gas at High Redshift project, which significantly expands the number of high-redshift galaxies with cold gas detections. Finally, Chapter 5 shows ALMA observations targeting emission from atomic carbon in a subset of the VLA targets, and demonstrates how this alternative gas tracer complements our view of cold molecular gas reservoirs at high—redshift. Show less
This thesis discusses the prenatal detection and outcome of fetal congenital heart defects. The first part of this thesis focuses to identify determinants for a prenatal diagnosis in fetus with a... Show moreThis thesis discusses the prenatal detection and outcome of fetal congenital heart defects. The first part of this thesis focuses to identify determinants for a prenatal diagnosis in fetus with a structural congenital heart defect. The second part provides evidence on the prognosis of specific congenital heart defects diagnoses in the fetus, as prenatal counseling remains difficult in some cases, due to the fact that little evidence is available on the outcome of congenital heart defects from a fetal perspective. Show less
Dubbeldeman, E.M.; Crone, M.R.; Jong, J.C.K.D.; Kleij, R.M.J.J. van der 2024
Introduction Behavior change techniques (BCTs) are considered as active components of implementation strate‑ gies, infuencing determinants and, ultimately, implementation performance. In our... Show moreIntroduction Behavior change techniques (BCTs) are considered as active components of implementation strate‑ gies, infuencing determinants and, ultimately, implementation performance. In our previous Delphi study, experts formulated ‘implementation hypotheses’, detailing how specifc combinations of BCTs and strategies (referred to as BCT-strategy combinations) might infuence determinants and guideline implementation within youth care. For example, educational meetings providing instructions on guideline use were hypothesized to enhance practition‑ ers’ knowledge and, consequently, guideline implementation. However, these hypotheses have not been verifed in practice yet. Method We conducted a cross-sectional study involving practitioners and management professionals from youth (health)care organizations. Using questionnaires, we obtained data on the presence of BCT-strategy combinations and their perceived infuence on determinants and implementation performance. Chi-squared tests and regres‑ sion analyses were employed to determine the infuence of specifc BCT-strategy combinations on determinants and implementation performance. Results Our analyses included data from 104 practitioners and 34 management professionals. Most of the manage‑ ment professionals indicated that the BCT-strategy combinations positively infuenced or had the potential to infu‑ ence their implementation performance. At the practitioner level, half of the combinations were perceived to have a positive infuence on determinants and implementation performance. Furthermore, practitioners who reported the absence of BCT-strategy combinations were more skeptical about their potential infuence on determinants and implementation performance. Conclusion Several BCT-strategy combinations were perceived to improve or potentially improve implementation performance of both practitioners and management professionals. In the development and evaluation of imple‑ mentation eforts, we advocate for clearly describing the implementation efort’s objective and using frameworks that detail the BCTs inducing behavior change, the strategy employed, and the processes driving the observed changes. Understanding these interconnected processes is important in designing targeted, evidence-based Show less
Scientometrics originate from the analysis of scientific publications, the most popular ways for disseminating scientific information within the scientific community. With the increasing use of... Show moreScientometrics originate from the analysis of scientific publications, the most popular ways for disseminating scientific information within the scientific community. With the increasing use of scientometric data in research management and research evaluation, various analyses can be conducted to better understand different aspects of scientific activities. On the one hand, the analysis of scientific publications from the Middle East and North Africa region opens up a range of possibilities to characterize its science systems. Large scale analyses of bibliographic metadata capture the stories of how the scientific workforce is connected, funded and mobile within diverse science systems. On the other hand, scientometric data is also used as a guide to transform the science systems. The main objective of this dissertation is to better understand recent science systems changes in the Middle East and North Africa by examining several of their facets and their recent evolution. Show less
All living organisms are made out of cells, which serve as the fundamental units of life. Protein molecules, comprised of amino acids, carry out diverse functions across various cellular... Show moreAll living organisms are made out of cells, which serve as the fundamental units of life. Protein molecules, comprised of amino acids, carry out diverse functions across various cellular compartments. Proteins are tightly controlled in their synthesis, folding, localization and degradation to ensure proper functioning. Dysregulation of protein control mechanisms within the cell can lead to cellular dysfunction, disease or eventually cell death. Post-translational modifications (PTMs) are the addition of a chemical group to an existing protein to regulate its function, localization, stability or interaction. In this thesis we will dive deeper into PTMs SUMO and ubiquitin, with the aim to understand the biochemistry of these proteins in different aspects of cellular function and human pathophysiology. An interesting aspect of the conjugation process lies in its reversibility, which is governed by specific proteases known as SENPs in the case of SUMO. However, only SENP6 and SENP7 have the ability to depolymerize SUMO2/3 chains by an insertion in their conserved catalytic domains. We delve into the promising horizon that lies ahead of a small yet profoundly impactful post-translational modifying protein. Despite its modest size, this protein wields a significant influence on fundamental cellular processes Show less
The Dutch reward system in prison (Promoveren en Degraderen) has never been formally evaluated, therewith obscuring its theoretical soundness, application and effects. There are scholarly concerns,... Show moreThe Dutch reward system in prison (Promoveren en Degraderen) has never been formally evaluated, therewith obscuring its theoretical soundness, application and effects. There are scholarly concerns, however, regarding all three of these aspects. Therefore, the current dissertation aims to improve our understanding of reward systems in prisons, by studying the Dutch reward system in prison. Specifically, the soundness of its theoretical assumptions is tested, prior research is mapped, predictors of receiving rewards are identified (e.g. motivation, self-governance ability and behaviour), and the association between rewards and feelings of autonomy is examined.The current dissertation reveals that the theoretical assumptions can only partially be supported by scientific knowledge and that the system is not fully applied as intended. Moreover, the current reward system disadvantages incarcerated individuals low on self-governance ability. Finally, some rewards do increase feelings of autonomy in prison. These results underscore the relevance of promoting intrinsic over extrinsic motivation for compliance, and of adapting the current system to the level of self-governance ability of incarcerated individuals. Policymakers are advised to effectuate such policy changes, and practitioners are advised to look beyond behaviour as the key determinant of who is ‘deserving’ of rewards. Show less
Central to this thesis was the use of human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) to model a rare form of mitochondrial cardiomyopathy. To model this disease required the... Show moreCentral to this thesis was the use of human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) to model a rare form of mitochondrial cardiomyopathy. To model this disease required the design of new methodologies, improving upon the current limitations of hiPSC-CMs as model systems, notably the variability and the immature state of the resulting cardiomyocytes. The diseases we were interested in manifest soon after birth. At the outset of the studies, it was unclear whether a phenotype would be evident in our standard immature 2D cultures, or whether more complex models would be required to capture more salient features of the condition. Our focus was on the rare mitochondrial disease Combined Oxidative Phosphorylation Deficiency, caused by mutations in the gene alanyl-tRNA synthetase 2. We refined our emerging 3D cardiac microtissue protocol to improve robustness and reproducibility and reduce cost by basing differentiation on small molecules rather than growth factors without altering the functionality of hiPSC-CMs. We also demonstrated that integrating pH and O2 sensors in a micro-physiological chip was possible for the assessment of metabolic parameters under microfluidic flow. The overall goal of this thesis was to provide additional tools that would have utility in studying mitochondrial and other cardiac diseases. Show less
