Metabolomics, proteomics, and genomics analyses provide profound insight into human biology and disease pathophysiology. In this thesis, we explored the methodological challenges facing these OMICs... Show moreMetabolomics, proteomics, and genomics analyses provide profound insight into human biology and disease pathophysiology. In this thesis, we explored the methodological challenges facing these OMICs technologies and illustrated their applications in epidemiological studies. In part one, we focused on some of the methodological challenges facing OMICs research. These challenges included handling missing data in metabolomics, measurement agreement between high throughput proteomic measurements with standard clinical measurements, and challenges in developing prediction models using metabolomic data. The second part of this thesis addressed various epidemiological research questions by utilizing genomic data and metabolomics measurements (Metabolon and Nightingale platforms) and using advanced data analysis methods. These studies provided important insights into the associations between metabolites and hepatic triglyceride content, the associations of between the size of cytosine-adenine-guanine nucleotide repeats in the huntingtin gene with metabolomic profile, and the associations of the man-made per- and polyfluoroalkyl substances (PFAS) with metabolite levels. Show less
The aim of this thesis was to study the cardiometabolic consequences of obesity and weight gain during the life course. We investigated the association between body mass index (BMI) and... Show moreThe aim of this thesis was to study the cardiometabolic consequences of obesity and weight gain during the life course. We investigated the association between body mass index (BMI) and cardiometabolic disease using Mendelian randomization. We observed that all BMI-associated gene sets, grouped based on tissue expression, were similarly associated with increased risks of cardiometabolic disease. We observed that abdominal adiposity in adolescence was associated with early changes in metabolomic measures indicative of an atherogenic profile already present in young men. Weight gain during adulthood was specifically related to an atherogenic metabolic profile, in addition to increased adipocyte size. Adult weight gain between age 20 years and middle age was associated with increased visceral and liver fat at middle age. Additionally, the association between adult weight gain and insulin resistance at middle age was partly mediated by increased levels of visceral and liver fat at middle age. Lastly, we observed that a favourable body fat distribution as well as metabolic profile are associated with a decreased risk of incident cardiometabolic disease in a population with obesity. Overall, the results of this thesis emphasize the importance of maintaining a stable body weight during young adulthood throughout middle age. Show less
This thesis aimed to explore biochemical processes related to migraine outside (interictal) and during upcoming attacks. Chapter 2 describes the biochemical profiling of plasma samples from... Show moreThis thesis aimed to explore biochemical processes related to migraine outside (interictal) and during upcoming attacks. Chapter 2 describes the biochemical profiling of plasma samples from interictal migraine patients and healthy controls from eight Dutch cohorts with a proton nuclear magnetic resonance based metabolomics platform. In Chapter 3 cerebrospinal fluid (CSF) and plasma samples from interictal migraine with and without aura patients and healthy volunteers, were profiled using an ultra-performance liquid chromatography mass spectrometry (UPLC-MS) platform for amine measurements, as multiple amines have been implicated in migraine pathophysiology. Alcoholic beverages are frequently reported migraine triggers. Chapter 4 assessed the potential of various alcohol beverages as a migraine attack trigger using a questionnaire study in a large cohort of migraine patients. In Chapter 5, the frequently used pharmacological migraine trigger glyceryl trinitrate (GTN) was studied in migraine patients and healthy controls to investigate whether previously reported premonitory symptoms are indeed specific to migraine patients. In Chapter 6 glutamate, glutamine, and GABA were assed in the visual cortex of migraine patients before and over the course of a GTN-provoked attack to detect possible involvement of the glutamatergic system in the onset of attacks using proton magnetic resonance spectroscopy. Show less
The research in this thesis is divided into two parts. Part I consists of biochemical studies in migraine, a paroxysmal brain disorder where visual disturbances may form a part of the migraine... Show moreThe research in this thesis is divided into two parts. Part I consists of biochemical studies in migraine, a paroxysmal brain disorder where visual disturbances may form a part of the migraine attack. The main objective was quantification of amine neurotransmitters and other amine molecules in cerebrospinal fluid and plasma of migraine patients, and compare these concentrations with those from healthy controls. Part II describes the clinical relation between migraine and visual snow, a brain disorder with continuous visual disturbances and that is possibly associated with migraine. Since not much is known about this relationship this thesis presents observational studies on the incidence of comorbid migraine in visual snow. Show less
In this thesis, the systemic host metabolic response to experimental Opistorchis felineus infection using Nuclear Magnetic Resonance spectroscopy has been investigated. Overall, the studies... Show moreIn this thesis, the systemic host metabolic response to experimental Opistorchis felineus infection using Nuclear Magnetic Resonance spectroscopy has been investigated. Overall, the studies examined the experimental model of opisthorchiasis, which included male and female animals, mild and severe infections, acute and chronic as well as biofluids and organs. Multi-block data analysis was applied to the model of chronic opisthorchiasis to delineate how infection affects the metabolic profile of infected versus uninfected animals at a detailed level, enhancing our understanding of this neglected disease affecting 56 million worldwide. Show less
This thesis aimed to provide insight in the etiology, predictors, and outcomes of aggression and antisocial behavior in children and adolescents. The first part of this thesis focused on more... Show moreThis thesis aimed to provide insight in the etiology, predictors, and outcomes of aggression and antisocial behavior in children and adolescents. The first part of this thesis focused on more conventional prediction of outcomes and continuation of aggression and antisocial behavior on the basis of the following constructs: parental psychopathology (Chapter 2), anxiety and depression (Chapter 3), and Oppositional Defiant Disorder symptoms (Chapter 4). Next, the second part of this thesis focused on novel biological markers of aggression, consisting of a review on the genetics of aggression (Chapter 5) and an empirical study on the metabolomics of aggression (Chapter 6). Chapter 7 provides a summary and general discussion of the thesis' contents. Show less
In this thesis, we focus on recipients of donation after circulatory death (DCD) kidneys in the first months after transplantation. DCD kidney transplant recipients have an increased risk of early... Show moreIn this thesis, we focus on recipients of donation after circulatory death (DCD) kidneys in the first months after transplantation. DCD kidney transplant recipients have an increased risk of early complications post transplantation such as acute rejection and delayed graft function (DGF). A sensitive and specific biomarker to monitor the occurrence of an acute rejection episode or (the resolution of) DGF is unfortunately not available to date. For a definite diagnosis, a kidney allograft biopsy remains the so-called ‘golden standard’. A percutaneous kidney biopsy is, however, an invasive procedure with a risk of bleeding complications. Guidance in daily clinical practice by a simple but reliable marker is needed, and can help to monitor regular resolution of DGF and/or identify intercurrent problems such as acute rejection episodes. In the current thesis we investigated risk factors of acute rejection and DGF. In addition, the most promising biomarkers of kidney injury according to current literature (i.e. KIM-1, NGAL, TIMP-2, IGFBP7) were investigated in the prediction of DGF and acute rejection. Furthermore, we used an alternative approach in the search for biomarkers by analyzing smaller molecules with Nuclear Magnetic Resonance (NMR) spectroscopy.We still have not found the ‘perfect’ biomarker to monitor acute rejection DGF after kidney transplantation, however of all biomarkers investigated TIMP-2 showed the greatest potential. Using the approach of metabolomics, we were able to identify new biomarkers. Further studies are needed to confirm and validate these results and evaluate their usefulness in daily clinical practice. Show less
Cardiovascular disease and diabetes are one of the leading causes of death worldwide. Multiple genetic and non-genetic factors play a role in this process. This dissertation aims to study the... Show moreCardiovascular disease and diabetes are one of the leading causes of death worldwide. Multiple genetic and non-genetic factors play a role in this process. This dissertation aims to study the interplay between genetic factors and lifestyle factors (eg sleep, nutrition, physical activity) with diseases such as cardiovascular disease and risk factors for cardiovascular disease (diabetes). For example, 12 blood biomarkers associated with insulin resistance have been identified, 5 of which are specifically much higher in subjects with diabetes. In addition, it appeared that a short sleep duration and poor sleep quality are associated with poorer lipids in the blood (eg cholesterol and LDL) and more insulin resistance. With regard to sleep, 59 new genetic variants have also been identified with regard to blood lipids (HDL, LDL, triglycerides). In addition, the results indicate that a better lifestyle can also help reduce the development of new cardiovascular diseases in people with an increased genetic risk. This is particularly interesting to prevent diseases in persons at high risk. All in all, this thesis has provided new insights into the various factors that are potentially important in the development of cardiovascular disease and diabetes. Show less
Diabetes mellitus type 2 (DM) is a major risk factor for developing active tuberculosis (TB) disease, yet the causal mechanisms driving this association remain largely elusive. As the incidence of... Show moreDiabetes mellitus type 2 (DM) is a major risk factor for developing active tuberculosis (TB) disease, yet the causal mechanisms driving this association remain largely elusive. As the incidence of DM is rising, especially in TB endemic countries, it is important to identify the relevant immunological and metabolic processes that underlie TB-DM comorbidity, because such insights will facilitate optimal treatment, diagnosis and prevention. In this thesis, we have started to unravel key factors underlying the association between TBand DM using two approaches. Firstly, we identified and analyzed human macrophage subsets and studied the interactions between these human cells and a major pathogen, Mycobacterium tuberculosis (Mtb), and the specific metabolic changes involved using well-controlled in vitro systems. Next, we employed metabolomics to determine the impact of concurrent TB-DM on circulating metabolites in patient cohorts ex vivo. In this thesis we present evidence derived from in vitro experiments and from ex vivo observational data which collectively suggest a pathogenic role of atherogenic lipid species during TB development. Show less
This thesis provides insights into the mechanisms of renal I/R injury based on human kidney transplantation (i.e. the status of delayed graft function: DGF). A severe energetic crisis... Show moreThis thesis provides insights into the mechanisms of renal I/R injury based on human kidney transplantation (i.e. the status of delayed graft function: DGF). A severe energetic crisis differentiates DGF kidneys from adequately functioning controls. Although intact beta-oxidation, aerobic glycolysis and glutaminolysis provide Krebs Cycle intermediates, these intermediates are not able to enter the mitochondrial Krebs cycle. Hence, dysfunctional mitochondria disable efficient ATP production leading to the metabolic incompetence that causes DGF and underlies renal I/R injury. This finding sheds a whole new light on I/R injury and explains why ATP-dependent therapeutics are ineffective as treatment for I/R injury. A major difference in the vulnerability of mitochondria to ischemia and reperfusion between rodents and humans was found. This could explain the current differences in effectiveness of therapies in the experimental versus the clinical setting. Big cohort studies give insights in donor, recipient and transplant-procedure variables and challenge the reluctance towards the use of DCD donor kidneys. New preventive strategies could limit I/R injury by preserving mitochondria (hypothetically with peptide SS-31 or activation of mitochondrial aldehyde dehydrogenase). This will overcome the detrimental effects of I/R injury on graft function and survival - thereby increasing the success rate of kidney transplantation. Show less
Het doel van dit proefschrift was daarom de onderliggende biochemische processen gerelateerd aan migraine te onderzoeken. Het eerste gedeelte (Hoofdstukken 2 en 3) beschrijft twee onderzoeken... Show moreHet doel van dit proefschrift was daarom de onderliggende biochemische processen gerelateerd aan migraine te onderzoeken. Het eerste gedeelte (Hoofdstukken 2 en 3) beschrijft twee onderzoeken waarin gekeken is naar de biochemische constitutie van de hersenen van migraine patiënten door middel van proton magnetische resonantie spectroscopie (1H-MRS) en diffusie gewogen spectroscopie (DWS). In het tweede gedeelte (Hoofdstukken 4 en 5) wordt een systematische review met meta-analyse beschreven om een overzicht te geven van eerdere inspanningen om in verschillende lichaamsvloeistoffen biochemische verschillen te detecteren die relevant zijn voor migraine. Daarnaast wordt er een studie beschreven waarin is gekeken naar biochemische verschillen in liquor van migraine patiënten en gezonde controles. In het derde gedeelte worden twee methodologische studies beschreven waarin (Hoofdstukken 6 en 7) de biochemische stabiliteit van liquor en het effect van vervuiling met ethanol werden onderzocht. Show less
The work described in this thesis presents part of a framework that can be used to extract detailed disease biological information from peripheral tissue. This framework is based on the... Show moreThe work described in this thesis presents part of a framework that can be used to extract detailed disease biological information from peripheral tissue. This framework is based on the central dogma of biology “DNA to RNA to protein” and on a systems biology approach that aims to produce synergetic data whose disease pathological, prognostic and predictive value is greater than the sum of the individual experiment results. HD patients are often characterized by a multifaceted clinical profile, consisting of several symptoms and variable disease progression rates. Therefore, a systems approach such as the one described above is expected to be the most effective in identifying potential treatments and predictive biomarkers that will be most informative for the different patient subpopulations. Show less
