This thesis provides novel insights in the capacity of photodynamic therapy (PDT) to disrupt the tumor and its vasculature for improved accumulation of nanosized drug carriers in the tumor.... Show moreThis thesis provides novel insights in the capacity of photodynamic therapy (PDT) to disrupt the tumor and its vasculature for improved accumulation of nanosized drug carriers in the tumor. Moreover, it has shown the importance of the origin and physiological state of extracellular vesicles used as carriers for photosensitizers. It has also expanded knowledge of PDT-induced immunogenic cell death through damage-associated molecular pattern exposure and release that can initiate specific antitumor immune responses. Furthermore, several chapters identify combinations of PDT and immunotherapy that improve the therapeutic efficacy compared to currently used treatment options. Future studies that further investigate ways to benefit from the immunostimulatory effects of PDT hold great promise and may introduce exciting new modalities for improved treatments of cancer. Show less
The research described in this thesis aims at the development of ubiquitin-based research tools to study the enzymes of the ubiquitination pathway, the ligase enzymes and the deubiquitinating... Show moreThe research described in this thesis aims at the development of ubiquitin-based research tools to study the enzymes of the ubiquitination pathway, the ligase enzymes and the deubiquitinating enzymes. These enzymes are responsible for the conjugation and the removal of the post-translational modifier ubiquitin. This small protein is involved in almost all cellular processes, and when conjugated onto a substrate protein it can signal for degradation and influence the localization, interaction, stability and activity of the protein. Therefore, the dysregulation of these processes can have detrimental effects of cell organization and survival which in turn has implications in numerous processes related to diseases. Hence, it is important to fully understand the ubiquitination pathway and how to interact with it. The ubiquitin-based research tools described in this thesis aim to shine light on parts of this pathway. Ranging from the selectivity and specificity of DUBs for specific Ub linkages in competition and the catalytic efficiency of these proteolytic cleavage processes to the selectivity and activity of ligases and the activity of DUBs in cells. All ubiquitin research tools are based on synthetic ubiquitin modified with unnatural amino acids, neutron-encoded amino acids, point mutations and/or fluorescent labels, in order to study the characteristics of the enzymes in vitro. Show less
This thesis aims to improve our understanding of the genetic and clinical aspects of inherited syndromes associated with adenomatous polyposis in order to optimize surveillance and management and... Show moreThis thesis aims to improve our understanding of the genetic and clinical aspects of inherited syndromes associated with adenomatous polyposis in order to optimize surveillance and management and to improve life expectancy of these patients. Hereditary polyposis syndromes are a group of syndromes characterized by the development of multiple colorectal polyps and a high risk of developing colorectal cancer at an early age. Familial adenomatous polyposis (FAP) is the most common polyposis syndrome characterised by development of hundreds to thousands of adenomatous polyps. MUTYH-associated polyposis (MAP) is found in 10-20% of patients with polyposis. In the first part of this thesis, we examined genetic modifiers of cancer risk on the phenotype of FAP. In addition, we studied the occurrence of extracolonic malignancies and whether these malignancies are an important cause of death. We also studied the prevalence of Barret’s Oesophagus in a large cohort of patients with MAP and FAP. Patients with Constitutional mismatch-repair deficiency syndrome (CMMRD) develop a wide spectrum of malignancies beginning in childhood. In the second part, we developed a surveillance program to detect the most common cancers in patients with CMMRD and assessed the effectiveness of this surveillance program and discussed possible improvements of the protocol. Show less
Nowadays, therapeutic antibodies are the major and fastest growing class of biotherapeuticals. Since their invention, they are continuously developed to improve structural and functional... Show moreNowadays, therapeutic antibodies are the major and fastest growing class of biotherapeuticals. Since their invention, they are continuously developed to improve structural and functional characteristics. The high complexity of recently generated antibody derivatives, with various modifications induced during the manufacturing process itself leads to many proteoform variants of the desired product. These proteoforms can potentially exhibit altered activity. Therefore, an adequate characterization of the proteoforms, the assessment of their impact and careful monitoring of critical species is indispensable in order to guarantee effective and safe biopharmaceuticals. As the landscape of next-generation Ab formats continuously evolves, it is likewise of great importance to further develop appropriate analytical methods for their thorough attribute analysis. Hence, the focus of the research performed in this thesis is the development of multi-level approaches for the in-depth, primarily MS-based characterization of biopharmaceuticals to overcome the present restrictions and challenges arising e.g. by the implementation of complex Ab formats. Show less
Glycosylation is a widely occurring and complex modification found on lipids and proteins and is involved in the recognition, signaling and interaction events within the cell and between cells.... Show moreGlycosylation is a widely occurring and complex modification found on lipids and proteins and is involved in the recognition, signaling and interaction events within the cell and between cells. These events based on glycan structures result in adhesion, cell-matrix interaction and immune recognition. Alterations in the glycomic profile are considered a hallmark of various diseases, including cancer where it contributes to the development and progression of cancer, affecting cell-cell communication, cell-matrix interactions, tumor angiogenesis, invasion and metastasis. These functions are governed by different glycans and their terminal structures. In order to further explore these structures with regard to their potential as biomarkers and specific targets for diagnostic applications and therapeutical strategies for various diseases, in-depth glycomic analysis is needed. It is further noted that aberrant glycosylation not only results from the altered expression of glycosyltransferases (GTs) but also from the changed activity of GTs and glycosidases as well as the availability and abundance of sugar nucleotide donors. The aim of the research described in this thesis was to explore the glycomic signatures of colorectal cancer (CRC) in cell lines and tissues as well as of acute myeloid leukemia (AML) cell lines. Show less
Metagenomics enables the detection of all the genetic material of organisms present in a sample, making it a pathogen-agnostic approach for detecting common and rare or novel pathogens that are not... Show moreMetagenomics enables the detection of all the genetic material of organisms present in a sample, making it a pathogen-agnostic approach for detecting common and rare or novel pathogens that are not included in conventional testing. Beforehand, a clinician does not need to have a hypothesis of what pathogen is expected, unlike traditional polymerase chain reaction (PCR) testing.This thesis is focusing on diagnostic yield, clinical findings, and enhancing technical opportunities in viral metagenomics. The identification, typing, and quantification of viruses by means of viral metagenomics as a diagnostic tool are evaluated. Technical aspects are appraised for improved sensitivity and specificity of the wet and dry (bioinformatic) lab components of viral metagenomics. The use of a metagenomic protocol for virus discovery directly in a patient sample is assessed, and the best methods and approaches for performing genetic analysis of the SARS-CoV-2 virus are investigated.Viral metagenomic testing results in the identification of more viruses, therefore it is a valuable addition to current diagnostic test protocols. Additionally, it is a useful test for virus discovery and monitoring during infectious disease outbreaks caused by novel viruses. Show less
First the VG-RVPO as a monitoring for PAH in SSc patients was evaluated, here serial measurements of the VG-RVPO, can be used as a follow-up instrument to detect early changes in RV pressure over... Show moreFirst the VG-RVPO as a monitoring for PAH in SSc patients was evaluated, here serial measurements of the VG-RVPO, can be used as a follow-up instrument to detect early changes in RV pressure over time. Then we investigated the role of the VG-RVPO in improving the efficiency of the YEARS algorithm. Neither as a stand-alone diagnostic test nor when combined with the YEARS algorithm, it had any diagnostic value. Then the role of VG-RVPO in estimating the presence of PH, and the prognostic value of an abnormal VG-RVPO in PE patients was evaluated. There was an association between VG-RVPO and RV overload as measured by CTPA. In Chapter 5, the outcome of AAOCA patients is described and linked to pre-and postoperative symptoms. Overall, surgical correction significantly reduces symptoms. The CTOA on pre-and post-operative CTAs of patients with AAOCA was compared and related to anatomy and post-operative outcome. It suggests that CTA can be used to look at the anatomy of AAOCA patients before and after surgery. The last study re-evaluates the late clinical outcome and hemodynamics in patients with TOF. The findings shows, after 17.1 years there was a stabilization of RV function and an impressive durability of the homograft. Show less
Most organisms on Earth anticipate changes between day and night using an internal biological clock. This clock is localized in a small brain area: the suprachiasmatic nucleus (SCN). The SCN... Show moreMost organisms on Earth anticipate changes between day and night using an internal biological clock. This clock is localized in a small brain area: the suprachiasmatic nucleus (SCN). The SCN generates rhythms of approximately 24 hours (circadian) which are synchronized to light. We investigated how light signals reach the SCN and how the effects of light and behavioural activity on the SCN differ between diurnal and nocturnal species. In this thesis, we show that cone photoreceptors, involved in colour vision, contribute to the light responses of the circadian clock. As observed in fMRI experiments, the human SCN was also sensitive to different colours of light. Furthermore, the SCN of diurnal species was partly inhibited by light, whereas the SCN of nocturnal species was mostly excited. Finally, we observed that behavioural activity activates the SCN of diurnal species, whereas in nocturnal species the SCN is inhibited. We concluded that the input pathways to the circadian clock differ between diurnal and nocturnal species and hypothesize that these differences could contribute to the temporal activity profiles. Together, our findings facilitate the translation of circadian research from nocturnal laboratory animals to diurnal humans, for the benefit of biological rhythms and health in general. Show less
Cardiometabolic health is tightly controlled by a complex network of organ communication. Dysfunction of these lines of communication is associated with the development of cardiometabolic diseases... Show moreCardiometabolic health is tightly controlled by a complex network of organ communication. Dysfunction of these lines of communication is associated with the development of cardiometabolic diseases, indicating inter-organ cross-talk as a therapeutic target. Herein, I explored the therapeutic potential of targeting inter-organ communication in cardiometabolic diseases, including obesity, atherosclerotic cardiovascular disease and non-alcoholic steatohepatitis, based on which I proposed novel therapies to tackle these diseases. On one hand, strategies can focus on regulating the gut microbiota-centered inter-organ cross-talk. We demonstrated that dietary interventions are efficient to modulate the gut microbiota composition and function, thereby regulating the gut microbial metabolite production. In particularly, we showed that dietary supplementation of butyrate, a gut microbial metabolite, and choline, a nutrient enriched in red meat, can beneficially modulate the gut microbiota to alleviate adiposity. On the other hand, therapies can also focus on liver-centered inter-organ cross-talk. We showed that improving hepatocyte mitochondrial function by γ hydroxybutyric acid not only improves liver metabolic function, but also reverses obesity and its associated metabolic diseases. Besides, cardiometabolic health can be improved by regulating systemic levels of hepatokines (e.g. FGF21). We showed that FGF21-based pharmacotherapies can regulate the cross-talk between the liver and adipose tissue to improve cardiometabolic diseases, especially fibrotic non-alcoholic steatohepatitis and atherosclerotic cardiovascular disease. Thus, the findings described in this thesis emphasize the importance of inter-organ cross-talk for cardiometabolic diseases, and have improved our knowledge on the mechanisms that underlie the risk in the ever-increasing population of individuals who suffer from cardiometabolic diseases. Show less
In this thesis, the role of migraine as a cardiovascular risk factor is investigated in different populations with a varying medical history, including stroke and polycystic ovary syndrome (PCOS).... Show moreIn this thesis, the role of migraine as a cardiovascular risk factor is investigated in different populations with a varying medical history, including stroke and polycystic ovary syndrome (PCOS). We focused primarily on women and sex-specific features, exploring both conventional and novel measures for vascular health. This thesis was written in the context of the CREW consortium. The aim of the CREW consortium, a cooperation of major medical centers in the Netherlands and commissioned by the Dutch Heart Institute, was to study female-specific cardiovascular pathophysiology. The CREW-MIST (Cardiovascular Riskprofile in Women – MIcrovascular STatus) project, which was part of this consortium, focused on migraine in relation to stroke in women. Female-specific factors such as sex hormone- and pregnancy-related disorders were included in our studies and we explored microvascular health through heart- and brain imaging and functional measurements of the vasculature. Show less
The results described in this thesis expand and deepen the knowledge of the disease burden that several groups of Dutch travelers can face while traveling abroad and after returning home, varying... Show moreThe results described in this thesis expand and deepen the knowledge of the disease burden that several groups of Dutch travelers can face while traveling abroad and after returning home, varying from young medical students to the older traveler. One can think of communicable diseases (e.g. enteric- and respiratory infections), non-communicable diseases (e.g. exacerbation of cardiovascular diseases or mental disorders) and (road-traffic-related) injuries. In addition, travelers can also face non-medical challenges such as culture shock and violence. Travelers can also become colonized with resistant bacteria (e.g. ESBL-E) while staying abroad. Active surveillance and contact isolation precautions may then be recommended when a traveler returns from a destination in Asia, and is admitted to the hospital in the home country. The different studies provide more insights and practical advices regarding pre-travel information, which attributes both to practical tailored travel advice for Dutch travelers and will also be of interest for future research in the evolving world of travel medicine. Show less
Duchenne and Becker muscular dystrophy (DMD and BMD, respectively) are characterized by progressive loss of muscle function combined with an increase in fat tissue in muscle. In some muscles this... Show moreDuchenne and Becker muscular dystrophy (DMD and BMD, respectively) are characterized by progressive loss of muscle function combined with an increase in fat tissue in muscle. In some muscles this process of ‘fat replacement’ starts earlier or progresses faster than in others and this occurs in a consistent temporal pattern. In addition, even within muscles fat replacement seems to progress heterogeneously. Evidently there are factors that vary between and within muscles which cause differential fat replacement of muscle tissue, but these are currently unknown. The identification of factors that influence this process of muscle degeneration could support the selection of current, and the development of future, therapies.The aim of part 1 of this thesis was to identify differences between muscles that are related to muscle fat replacement over time. These can provide therapeutical targets for, and support the design of, future clinical trials in DMD and BMD. Part 2 aimed to develop new approaches to study intramuscular differences in muscle physiology and mechanics in healthy muscle. These can be applied in neuromuscular disease in the future, and can be related to intramuscular differences in disease progression. Show less
This thesis leads to empirical insights in the relationship between anger and aggression, on the one hand, and psychopathology, on the other hand, using robust study designs and a broad spectrum of... Show moreThis thesis leads to empirical insights in the relationship between anger and aggression, on the one hand, and psychopathology, on the other hand, using robust study designs and a broad spectrum of anger manifestations. It became clear that the occurrence of anger and aggression are common among both psychiatric outpatients, including individuals with depressive-, anxiety-, and bipolar disorders, and psychiatric inpatients, including individuals with psychotic- and personality disorders. Aggressive behaviour regularly leads to a referral to long-stay inpatient care. As supported by this thesis, the costs of aggression within long-stay wards are high. However, despite the increased awareness and efforts to reduce violence in clinical care among healthcare workers and policymakers, aggression incidents remain highly prevalent in psychiatric inpatient facilities. Research suggests diet to be a modifiable factor affecting mood and behaviour. Yet, the promising effects of nutritional supplementation on aggressive incidents found in previous studies were not replicated in psychiatric inpatients. These results strengthen the need for study of additional preventative and treatment options. Furthermore, our results underline the importance of including vulnerable populations, who are often underrepresented in RCTs, to provide evidence-based care for these groups. Show less
The work of this thesis was to develop and use such a computational model to offer insight into the working mechanisms of cochlear implant stimulation and to enable virtual experiments that would... Show moreThe work of this thesis was to develop and use such a computational model to offer insight into the working mechanisms of cochlear implant stimulation and to enable virtual experiments that would be unfeasible or outright impossible in real life. The model that was used for this thesis was not built from scratch but was an updated and expanded version of the one developed at Leiden University Medical Centre by Johan H.M. Frijns and Jeroen J. Briaire. In essence, this thesis forms a continuation of their PhD work. The general goals of each of the modelling studies presented in this thesis were:(I) To improve the accuracy of the Leiden computational cochlear implant model to gain a better understanding of cochlear implant-induced hearing.(II) Where possible, validate the model using available data from electrophysiological or psychophysical experiments.(III) To use the model to offer predictions that may help to improve the function or design of cochlear implants in the future. Show less
In this thesis, solid phase peptide synthesis (SPPS) and chemical protein synthesis are used to synthesize novel tools such as assay-reagents and activity-based probes based on Ubiquitin-like... Show moreIn this thesis, solid phase peptide synthesis (SPPS) and chemical protein synthesis are used to synthesize novel tools such as assay-reagents and activity-based probes based on Ubiquitin-like proteins. These probes are used to explore the function and specificity of deconjugation enzymes. Show less
Vulvar cancer is a rare gynecological malignancy with a tremendous disease burden. Vulvar squamous cell carcinoma (VSCC) is the most common histologic type of vulvar cancer and constitutes 80–90%... Show moreVulvar cancer is a rare gynecological malignancy with a tremendous disease burden. Vulvar squamous cell carcinoma (VSCC) is the most common histologic type of vulvar cancer and constitutes 80–90% of all vulvar cancers. The cornerstone of treatment for VSCC consists of surgery with or without radiochemotherapy. In addition, precursors of VSCC often require surgical or medical intervention as well. Treatment of vulvar (pre)malignancies is a challenging balance act, as on the one hand clearance of all lesions is desired, while on the other hand normal vulvar anatomy and function must be preserved as best as possible. Utilizing the current treatment interventions, recurrence occurs in up to 40% of VSCC patients and no major improvements in 5-year survival rates were observed in the last decades. This is partly caused by the difficulty to recognize vulvar (pre)malignant lesionsfor the medical specialist, either macroscopically or pathologically.This highlights the high unmet medical need for preferably non-invasive and accurate diagnostics for vulvar (pre)malignancies. Further, effective therapies are needed with a favorable safety profile that encompass complete reduction of the affected tissue.Therefore, the aim of this thesis has been to search for disease-specific biomarkers to improve the clinical management of vulvar (pre)malignancies. In the present thesis, we have attempted to test several promising innovative instruments in a search for disease-specific biomarkers for vulvar (pre)cancers. A multimodal profiling approach guided this research, based on systems profiling of disease and drug effects in dermatology. The different investigated aspects include imaging, cellular and molecular characteristics and was complemented by patient reported outcomes and physician-based input. Overall we focused on three important cornerstones within this multimodal approach:1 Application of novel non-invasive imaging instruments as dermatoscopy, optical coherence tomography and reflectance confocal microscopy on healthy and diseases vulvar skin to improve diagnostics;2 Establishment of in vitro healthy and VSCC 3D models aimed for future anticancer drug evaluation studies;3 Investigation of promising targets for tumor-specific molecular real time imaging of vulvar (pre)cancers, to assist complete surgical excision. Show less
Cardiovascular diseases (CVD) are the leading mortality cause. Its largest underlying issue is atherosclerosis: arterial narrowing due to the buildup of cholesterol, lipids, and immune cells. High... Show moreCardiovascular diseases (CVD) are the leading mortality cause. Its largest underlying issue is atherosclerosis: arterial narrowing due to the buildup of cholesterol, lipids, and immune cells. High blood pressure and cholesterol levels are well-known risk factors. Despite the effectiveness of currently-available medication to improve these factors, a considerable residual risk remains, indicating the importance of other risk factors, such as age and sex. Women have a lower risk of developing CVD than men at a young age, which reverses at older age. CVD are also more common among night shift workers. The research described in this thesis used mouse models to provide new insight in the interplay between sex, age, and disturbances in day and night rhythms in atherosclerosis development, and emphasize the importance of including both men and women in scientific studies. Brown fat is one of the tissues adversely affected by disturbances in day and night rhythms and aging, and the ANGPTL4 protein was identified as an important regulator of brown fat. Inhibiting ANGPTL4 production selectively in liver cells appears a safe and promising therapeutic strategy to combat atherosclerosis. The findings also imply that time-restricted eating could be an effective tool in lowering CVD risk in shift workers. Show less
This thesis aims to improve the treatment of patients with stage III melanoma. The first part describes different aspects of treatment with Talimogene Laherparepvec (T-VEC), a genetically modified... Show moreThis thesis aims to improve the treatment of patients with stage III melanoma. The first part describes different aspects of treatment with Talimogene Laherparepvec (T-VEC), a genetically modified herpes virus, which is used as oncolytic immunotherapy for skin and lymph node metastases in melanoma patients. We show that patients with a low tumor burden have the best outcomes, suggesting T-VEC should be used earlier on in the course of the disease. We present a prediction model, allowing a more accurate selection of patients for T-VEC monotherapy. Two studies focused on the use of T-VEC in clinical practice and the results allowed us to make recommendations on the use of PET/CT and dermoscopy during T-VEC treatment. Part two focuses on the value of surveillance and screening imaging in high-risk melanoma patients. We show that FDG-PET/CT is a valuable imaging tool to detect recurrence after complete resection of stage III disease, even shortly after surgery (before starting adjuvant therapy). Finally, we conclude that nodal staging with US as adjunct to SLNB is useful in the work- up of stage IIB/C melanoma, as it can lead to alterations in treatment and prevent unnecessary surgery. Show less
This thesis focused on investigate immune compartmentalization in the developing human intestine, and lesional/healthy skin tissue from patients with mycosis fungoides and psoriasis by single-cell... Show moreThis thesis focused on investigate immune compartmentalization in the developing human intestine, and lesional/healthy skin tissue from patients with mycosis fungoides and psoriasis by single-cell spectral flow cytometry, suspension mass cytometry, single-cell RNA-sequencing, functional assays, RNAscope and imaging mass cytometry. Show less
Over the past decades increasing efforts have aimed to improve the health of pregnant women around the world. Namibia has made limited progress in reducing severe maternal outcomes. Aims of this... Show moreOver the past decades increasing efforts have aimed to improve the health of pregnant women around the world. Namibia has made limited progress in reducing severe maternal outcomes. Aims of this thesis were to enhance implementation of a national obstetric surveillance system and assess requirements to improve maternal health in Namibia. The findings of chapters 2-7 provided insight into several important drivers of severe maternal outcome. The most important contributor of the high-incidence of severe maternal outcome in Namibia was poor quality of facility-based care and particularly vulnerable women appeared to be at higher risk of severe maternal outcome. Obstetric surveillance played a crucial role in obtaining these insights. Based on these, targeted recommendations could be formulated. The maternity care system needs to be strengthened, to enable health workers to provide universal coverage of good health care to all women in Namibia. It is therefore crucial the next step will follow, which is to act on the proposed recommendations. The insights obtained through obstetric surveillance will contribute to such action, as for any intervention, it is key it addresses a local need in a context-specific manner. Show less
