A group of bacterial proteases, the Pro-Pro endopeptidases (PPEPs), pos-sess the unique ability to hydrolyze proline-proline bonds in proteins. Sincea protease’s function is largely determined by... Show moreA group of bacterial proteases, the Pro-Pro endopeptidases (PPEPs), pos-sess the unique ability to hydrolyze proline-proline bonds in proteins. Sincea protease’s function is largely determined by its substrate specificity,methods that can extensively characterize substrate specificity are valuabletools for protease research. Previously, we achieved an in-depth characteri-zation of PPEP prime-side specificity. However, PPEP specificity is alsodetermined by the non-prime-side residues in the substrate. To gain a morecomplete insight into the determinants of PPEP specificity, we character-ized the non-prime- and prime-side specificity of various PPEPs using acombination of synthetic combinatorial peptide libraries and mass spec-trometry. With this approach, we deepened our understanding of the P3-P30 specificities of PPEP-1 and PPEP-2, while identifying the endogenoussubstrate of PPEP-2 as the most optimal substrate in our library data. Fur-thermore, by employing the library approach, we investigated the alteredspecificity of mutants of PPEP-1 and PPEP-2. Additionally, we character-ized a novel PPEP from Anoxybacillus tepidamans, which we termed PPEP-4. Based on structural comparisons, we hypothesized that PPEP-4 displaysa PPEP-1-like prime-side specificity, which was substantiated by the experi-mental data. Intriguingly, another putative PPEP from Clostridioides diffi-cile, CD1597, did not display Pro-Pro endoproteolytic activity.Collectively, we characterized PPEP specificity in detail using our robustpeptide library method and, together with additional structural informa-tion, provide more insight into the intricate mechanisms that govern prote-ase specificity. Show less
Malaria continues to wreak havoc in tropical regions, due largely to the lack of an effective vaccine. Vaccine candidates based on whole parasites have shown promising results in malaria-naïve... Show moreMalaria continues to wreak havoc in tropical regions, due largely to the lack of an effective vaccine. Vaccine candidates based on whole parasites have shown promising results in malaria-naïve individuals, but their potency in malaria-exposed individuals is considerably lower. This dissertation described the development of a chemical strategy for boosting such parasites’ potency in pursuit of more efficacious malaria vaccines for use in endemic areas.Chapter 2 outlined the adaptation of a method for chemically modifying microbial cell surfaces.Chapter 3 showed the chemistry underlying this modification system to be stably compatible with in vivo usage.Chapter 4 demonstrated that when the chemical modification system was used to introduce immune-potentiating agents onto bacteria, better immune responses ensued.Chapter 5 tied it all together by using the chemical modification system to potentiate malaria parasites, and showed that doing so markedly improved immune responses in an in vivo immunization model.Chapter 6 summarized these findings in the context of malaria vaccine development and posited next steps forward. Show less
The dissertation investigates the role of lexical tone in spoken word recognition and production. In particular, it focuses on three groups of speakers: native speakers of Standard Chinese, bi... Show moreThe dissertation investigates the role of lexical tone in spoken word recognition and production. In particular, it focuses on three groups of speakers: native speakers of Standard Chinese, bi-dialectal speakers of Standard Chinese and Xi’an Mandarin, and bilingual speakers of Standard Chinese and English. Through a series of experiments employing the eye-tracking visual world paradigm and the picture-word interference paradigm, four key issues were explored: the role of lexical tone in Mandarin spoken word recognition; tonal interference in bi-dialectal spoken word recognition; the activation of lexical tone in bilingual spoken word production; and the influence of lexical tone on the bilingual mental lexicon. The findings of this dissertation not only showed how Mandarin listeners utilize tonal information during tone word recognition but also revealed dynamic tonal interaction between language systems. Overall, this dissertation contributes to a deeper understanding of lexical access by highlighting the significant role of lexical tone in both monolingual and bilingual contexts, shedding light on the intricate processes involved in spoken word recognition and production across languages. Show less
Manumission is the release from slavery, and therefore, a transition from the most extreme form of subjugation into another position and status in society. Some historians have defined manumission... Show moreManumission is the release from slavery, and therefore, a transition from the most extreme form of subjugation into another position and status in society. Some historians have defined manumission as a formal act, often understood as a gift that severed the bond between slave and master. More recently researchers have emphasized that it was a lengthy process that involved pre-existing dependencies and resulted in new hierarchies. This article takes a fresh look at the process and tries to gain a fuller understanding of manumission by examining it from the position of the manumitted and their social relations. Taking into consideration a wide range of documentary sources from colonial, notarial and Dutch governmental archives, we reconstruct the dependencies that were created in the process of manumission. The dependencies that evolved during manumission processes were related to family and other kinship ties, but also had an urban, communal, religious, economic and institutional logic. Manumission was not only an act at a specific moment, but also a process, and it was not a bilateral, but a multilateral one. With the instrument of manumission and within the limits set by economic reality and the colonial government, the manumittees tried to make meaningful life choices that transformed slave society profoundly. We find that they created complex dependencies across boundaries of status and racial categorization. Show less
During the Cold War, the Dutch Army Medical Service (MGD) promoted the health and operational readiness of the Royal Netherlands Army. Medical war preparations were an integral part of this. The... Show moreDuring the Cold War, the Dutch Army Medical Service (MGD) promoted the health and operational readiness of the Royal Netherlands Army. Medical war preparations were an integral part of this. The evacuation, treatment and nursing of sick and wounded soldiers in wartime required the formulation of procedures and doctrines as well as an extensive organization, complete with supplies and equipment, trained personnel and mobilization plans. However, these activities were shrouded in uncertainty as the prospect of biological, chemical or even nuclear warfare called into question all casualty estimations based on previous conflicts.The central question in this dissertation is how the MGD dealt with the nuclear threat perception and how military-medical war preparations were influenced by it. Against the backdrop of the ominous prospects of future warfare, military physicians tried to legitimize their war preparations and make sense of them. This mechanism is made clear using the concept of sociotechnical imaginaries: constructed optimistic images of the future that are based on the collective belief in scientific and technological progress. This study shows that the MGD maintained an optimistic outlook from the beginning through the end of the Cold War, but the reasoning that supported this viewpoint evolved over time. Show less
High-grade osteosarcoma, a primary malignant bone tumour, is experiencing a global increase in reported incidence with varied prevalence. Despite advances in management, which include surgery and... Show moreHigh-grade osteosarcoma, a primary malignant bone tumour, is experiencing a global increase in reported incidence with varied prevalence. Despite advances in management, which include surgery and neoadjuvant chemotherapy often an unsatisfactory outcome is found due to poor or heterogeneous response to chemotherapy. Our study delved into chemotherapy responses in osteosarcoma patients and associated molecular expressions, focusing on CD95 receptor (CD95R), interferon (IFN)-γ, catalase, heat-shock protein (Hsp)70, and vascular endothelial growth factor (VEGF). Employing immunohistochemistry and Huvos grading of post-chemo specimens, we analysed formalin-fxed parafn-embedded (FFPE) osteosarcoma tissue of resected post-chemotherapy specimens from Dr. Soetomo General Academic Hospital in Surabaya, Indonesia (DSGAH), spanning from 2016 to 2020. Results revealed varied responses (poor 40.38%, moderate 48.08%, good 11.54%) and distinct patterns in CD95R, IFN-γ, catalase, Hsp70, and VEGF expression. Signifcant diferences among response groups were observed in CD95R and IFN-γ expression in tumour-infltrating lymphocytes. The trend of diminishing CD95R expression from poor to good responses, accompanied by an increase in IFN-γ, implied a reduction in the count of viable osteosarcoma cells with the progression of Huvos grading. Catalase expression in osteosarcoma cells was consistently elevated in the poor response group, while Hsp70 expression was highest. VEGF expression in macrophages was signifcantly higher in the good response group. In conclusion, this study enhances our understanding of immune-chemotherapy interactions in osteosarcoma and identifes potential biomarkers for targeted interventions. Show less
Cancer immunotherapies utilizing immune checkpoint blockade (ICB) therapy targeting CTLA-4 and PD-1/PD-L1 relieve tumor-induced immune suppression and induce durable tumor regression. The use of... Show moreCancer immunotherapies utilizing immune checkpoint blockade (ICB) therapy targeting CTLA-4 and PD-1/PD-L1 relieve tumor-induced immune suppression and induce durable tumor regression. The use of ICB therapy have demonstrated remarkable therapeutic efficacy in a proportion of patients with melanoma. However, still a substantial percentage of patients does not respond (durable) to ICB treatment and many questions remain. Therefore, in this thesis, the aim is to improve our understanding of ICB efficacy. We demonstrate the promise of neoadjuvant ICB therapy (approach in which ICB therapy is applied before surgery) and analyze different cohorts of melanoma patients. This results in the identification of several markers that are associated with prognosis, including IFN-y related gene signature score, Batf3 dendritic cell associated gene signature score, tumor mutational burden and systemic LRG1 expression. These markers can potentially be targeted and might facilitate rational combination therapies that can boost the efficacy of ICB therapy. For this purpose, we perform a repurposing compound screen that targets antigen cross-presentation. Togethers, this work increases our understanding of factors that determine ICB therapy efficacy and toxicity, with the goal to identify novel strategies to improve outcome of melanoma patients in a rationale and personal manner. Show less
In this thesis we examined patient readiness for shared decision making (SDM) about treatment. We first assessed associations between patient-related characteristics and the occurrence of SDM.... Show moreIn this thesis we examined patient readiness for shared decision making (SDM) about treatment. We first assessed associations between patient-related characteristics and the occurrence of SDM. Overall, we did not find consistent associations between characteristics such as age or education level, and the extent to which SDM occurred (measured from the perspective of patients, clinicians, or observers). Second, we assessed what patients need to be ready, i.e., enabled and well-equipped, to participate in SDM about treatment. We identified a wide range of skills, cognitions, and emotions. For instance, patients need to be able to understand the relevant information, be able to and dare to express themselves in consultations with clinicians, and experience an adequate amount of time to talk to clinicians and to consider the options. Finally, we developed a questionnaire, the ReadySDM. The aim of the ReadySDM is to retrospectively measure the extent to which patients felt ready for SDM during a treatment decision-making process. The questionnaire has the potential to identify novel insights into patients’ support needs and ways to enhance SDM in daily practice. Show less
Toll-like receptor 2 (TLR2) belongs to the TLR protein family that plays an important role in the immune and inflammation response system. While TLR2 is predominantly expressed in immune cells, its... Show moreToll-like receptor 2 (TLR2) belongs to the TLR protein family that plays an important role in the immune and inflammation response system. While TLR2 is predominantly expressed in immune cells, its expression has also been detected in the brain, specifically in microglia and astrocytes. Recent studies indicate that genomic deletion of TLR2 can result in impaired neurobehavioural function. It is currently not clear if the genomic deletion of TLR2 leads to any alterations in the microstructural features of the brain. In the current study, we noninvasively assess microstructural changes in the brain of TLR2-deficient (tlr2-/-) zebrafish using state-of-the art magnetic resonance imaging (MRI) methods at ultrahigh magnetic field strength (17.6 T). A significant increase in cortical thickness and an overall trend towards increased brain volumes were observed in young tlr2-/- zebrafish. An elevated T2 relaxation time and significantly reduced apparent diffusion coefficient (ADC) unveil brain-wide microstructural alterations, potentially indicative of cytotoxic oedema and astrogliosis in the tlr2-/- zebrafish. Multicomponent analysis of the ADC diffusivity signal by the phasor approach shows an increase in the slow ADC component associated with restricted diffusion. Diffusion tensor imaging and diffusion kurtosis imaging analysis revealed diminished diffusivity and enhanced kurtosis in various white matter tracks in tlr2-/- compared with control zebrafish, identifying the microstructural underpinnings associated with compromised white matter integrity and axonal degeneration. Taken together, our findings demonstrate that the genomic deletion of TLR2 results in severe alterations to the microstructural features of the zebrafish brain. This study also highlights the potential of ultrahigh field diffusion MRI techniques in discerning exceptionally fine microstructural details within the small zebrafish brain, offering potential for investigating microstructural changes in zebrafish models of various brain diseases. Show less
Across the world, the number of citizen science projects focusing on plastic pollution is increasing. These projects often last for multiple years, which makes retaining volunteers challenging.... Show moreAcross the world, the number of citizen science projects focusing on plastic pollution is increasing. These projects often last for multiple years, which makes retaining volunteers challenging. However, our knowledge is limited regarding the effect of long-term involvement on citizen scientists’ motivation, attitude, and knowledge, especially for plastic pollution projects. Therefore, this study measured citizen scientists’ motivation, attitude, and knowledge in the Dutch Clean Rivers project before and during monitoring plastic pollution on riverbanks between 2017 and 2021.In total, 403 Clean Rivers participants completed a pre-survey, and a portion of them participated in one or multiple post-surveys throughout the years of monitoring. They were especially driven by Project Action motivations and Environmental motivations like tackling the source of pollution and doing something about the plastic soup, rather than being motivated by an Interest in Scientific Research like the desire to learn about scientific research. Project Action motivations increased significantly, especially within the first year of participation. Participants’ attitudes towards nature and science were initially high and did not increase significantly. Furthermore, while participants’ knowledge of plastic pollution was already high at the start, their knowledge of scientific research was not, and both increased significantly, especially in the first year of participation. The findings of this longitudinal study can contribute to improving the recruitment and retention of volunteers in current and future citizen science projects. Show less
