Duchenne muscular dystrophy (DMD) is the most prevalent neuromuscular disorder, caused by mutations in the DMD gene that prevent synthesis of dystrophin. Fibers that lack dystrophin are sensitive... Show moreDuchenne muscular dystrophy (DMD) is the most prevalent neuromuscular disorder, caused by mutations in the DMD gene that prevent synthesis of dystrophin. Fibers that lack dystrophin are sensitive to exercise-induced damage, resulting in progressive muscle wasting, loss of ambulation and premature death. There is no cure, but several therapeutic approaches are clinically tested. At best, these clinical interventions result in the expression of low dystrophin levels. Fortunately, expression of wild type levels is not needed, as both humans and mice expressing ~50% of dystrophin do not show pathology. Detailed studies on which dystrophin levels are needed to prevent pathology and improve muscle function have been performed in this thesis. After the set-up of good outcome measures and serum biomarkers to monitor disease progression, two new innovative mouse models expressing low levels of dystrophin based on skewed X-inactivation were generated. In the mdx-Xist__hs model we observed that <15% dystrophin already improved muscle performance, while histopathology was largely with >15% dystrophin. To protect muscles from exercise-induced damage >22% dystrophin was needed. Dystrophin levels between 3-21% prevent the development of dilated cardiomyopathy in 10 months old mice. Mice lacking both dystrophin and its homologue utrophin, mimic the human phenotype and die before the age of 12 weeks. In these mice, <10% dystrophin improved life expectancy and muscle function while >10% dystrophin was needed to improve histopathology. These findings are encouraging for ongoing and future clinical trails. Show less
Obesity is a major risk factor of osteoarthritis development and progression. Theoretically, obesity is a factor that can be modified. While obesity epidemic is difficult to reverse because we live... Show moreObesity is a major risk factor of osteoarthritis development and progression. Theoretically, obesity is a factor that can be modified. While obesity epidemic is difficult to reverse because we live in lipogenic environment, personal approach in modify obesity may avail. Therefore, understanding how obesity leads to osteoarthritis is needed. The first three chapters of this thesis investigate several aspects of osteoarthritis: what structures are damaged, what factors are associated with worsening of osteoarthritis and how to measure worsening of osteoarthritis. The other four chapters investigate the link between obesity and osteoarthritis. We show that obesity is associated with hand osteoarthritis. Since we do not walk on our hand, there must be another factor than mechanical that cause joint damage in osteoarthritis. One of the factors is adipokines, protein produced mainly by fat tissue. We showed that adiponectin, one of the adipokines, prevents worsening of hand osteoarthritis. We concluded that obesity plays role in osteoarthritis not only due to added mechanical force but also due to added metabolic force (adipokines). These adipokines might be used as target in modifying the effect of obesity on osteoarthritis. However, we still need more studies on how obesity links with osteoarthritis Show less
In this thesis the development of a pathophysiology-based method for the early evaluation of anthracycline-induced cardiotoxicity was described. We evaluated a comprehensive array of biomarkers,... Show moreIn this thesis the development of a pathophysiology-based method for the early evaluation of anthracycline-induced cardiotoxicity was described. We evaluated a comprehensive array of biomarkers, representing several aspects of anthracycline-induced cardiotoxicity, including cardiac injury and remodeling, free radical overload and the inflammation accompanying the injury. It was shown that predominantly the markers of cardiac injury may be suitable for the early detection of anthracycline-induced cardiotoxicity. In the second part of this thesis we evaluated a new, free-radical scavenging compound against anthracycline-induced cardiotoxicity using this approach. The failure of this compound to show efficacy against anthracycline-induced cardiotoxicity in our model suggests that a broader approach toward the mechanism of anthracycline-induced cardiotoxicity is necessary Show less
Sarasqueta, A.F.; Zeestraten, E.C.M.; Wezel, T. van; Lijnschoten, G. van; Eijk, R. van; Dekker, J.W.T.; ... ; Brule, A.J.C. van den 2011
Around 5-10% of patients with asthma do not respond adequately to inhaled steroids and long-acting bronchodilators and become difficult-to-treat; they remain symptomatic, have recurrent... Show moreAround 5-10% of patients with asthma do not respond adequately to inhaled steroids and long-acting bronchodilators and become difficult-to-treat; they remain symptomatic, have recurrent exacerbations or persistent airflow limitation. This thesis focuses on the mechanisms that may explain why these patients become difficult-to-treat and investigate biomarkers that can predict the development of specific asthma phenotypes. The different studies describe the possible role of alpha- antitrypsin in the development of persistent airflow limitation, the relationship between severity of asthma and the degree of peripheral airway inflammation and dysfunction, the clinical and inflammatory characteristics of obese patients with difficult-to-treat asthma, risk factors of lung function decline and the consistency of the eosinophilic phenotype Show less
The aim of this thesis was to study cardiovascular risk management in old age, in order to facilitate the development of age specific guidelines. In part one the current status of cardiovascular... Show moreThe aim of this thesis was to study cardiovascular risk management in old age, in order to facilitate the development of age specific guidelines. In part one the current status of cardiovascular prevention in old age is described, including a study into general practitioners__ attitudes and perceived barriers in this respect. The second part explores the incremental value of routine-ECGs for cardiovascular risk management in older persons from the general population, beyond existing information from medical records. The third part focuses on primary prevention, exploring the performance of classic risk factors, and some new biomarkers, in predicting cardiovascular mortality in very old people from the general population. It was concluded that a homocysteine level alone accurately identifies those at high risk of cardiovascular mortality, whereas classic risk factors included in the Framingham risk score do not. Next, in various age strata from age 55 years onwards, the association between blood pressure and mortality was studied. Finally, a systematic review into the diagnostic accuracy of natriuretic peptides for the diagnosis of chronic heart failure in older persons from the general population was performed, followed by a study in a cohort of nonagenarians into the prognostic value of NT-proBNP. A general discussion is provided, including directions for future research. Show less
The main objective of the research described in this thesis is to demonstrate the relevance of biomarkers on the selection of the dose range of COX inhibitors for effective analgesic and anti... Show moreThe main objective of the research described in this thesis is to demonstrate the relevance of biomarkers on the selection of the dose range of COX inhibitors for effective analgesic and anti-inflammatory response, as opposed to the focus on behavioural measures of pain and inflammation advocated by the current paradigm for the development of non-steroidal anti-inflammatory drugs (NSAIDs). To this end, the relationship between drug concentration and the corresponding inhibition of prostaglandin E2 (PGE2) and thromboxane B2 (TXB2) was investigated for a range of COX inhibitors with varying degrees of selectivity, and hence with differential effects on the selected biomarkers. Thanks to the use of a mechanism-based approach, attention is also given to translational pharmacology in drug development. We evaluate whether 1) estimates of drug action in vitro are predictive of the effect in vivo, 2) animal data in vivo reflect drug effect on biomarkers in humans and 3) whether inflammatory conditions modify the extent of drug effect as compared to healthy conditions. A recommendation and guideline for best practices in the development of COX inhibitors is anticipated from this analysis. Show less
Identification of translational and/or post-translational modifications of cardiac proteins after acute myocardial infarction (AMI) or during the progression to congestive heart failure (CHF) is... Show moreIdentification of translational and/or post-translational modifications of cardiac proteins after acute myocardial infarction (AMI) or during the progression to congestive heart failure (CHF) is relevant to gain insight into the pathological mechanisms. Characterization of the release kinetics of these cardiac proteins from the reversibly or irreversibly injured myocardium into the circulation may lead to new diagnostic biomarkers. Although cardiac Troponin I (cTnI) is a well-known biomarker of irreversible myocardial damage in acute myocardial infarction, we demonstrated that the release of cTnI also occurs from viable cardiomyocytes by a stretch-related mechanism, mediated by integrin stimulation. This finding may explain why in several pathological conditions, such as CHF, plasma cTnI levels are elevated in the absence of myocardial necrosis. In addition, we investigated the role of Tenascin-C re-expression during the development of heart failure and the relevance of TNC as a biomarker of ventricular remodeling. In animals with pressure-overload induced ventricle dilatation, TNC gene expression was upregulated, resulting in re-expression of myocardial TNC protein levels and elevated TNC plasma levels, correlating with cardiac function. Plasma TNC levels in patients with CHF declined during cardiac resynchronization therapy. This study indicates that serial plasma TNC levels can be used as a marker of adverse or reverse ventricular remodeling. Show less
In the studies comprising this thesis we evaluated the potential usefulness of cDNA microarray based gene expression profiling and 1H-NMR based metabolomics platforms as tools for the evaluation of... Show moreIn the studies comprising this thesis we evaluated the potential usefulness of cDNA microarray based gene expression profiling and 1H-NMR based metabolomics platforms as tools for the evaluation of novel PPAR_ and -_ agonists in future clinical __proof of concept studies__. We investigated the effects of rosiglitazone, (prototype PPAR_ agonist ) and ciprofibrate (prototype PPAR_ agonist) on global (target) tissue gene expression profiles and endogenous urinary and plasma metabolites of type 2 Diabetes Mellitus (T2DM) patients and healthy volunteers (HVs).The results from the transcriptomic analyses indicated that none of the genes in any of the tissues in either study group displayed a significant treatment response with either rosiglitazone of ciprofibrate vs. placebo at Bonferroni adjusted values and _=0.05. The results of the metabolomic analyses revealed significant rosiglitazone and ciprofibrate induced changes in endogenous urinary and plasma metabolite profiles of T2DM patients but not in HVs. We conclude that from the two molecular profiling platforms evaluated in this thesis, metabolomics currently appears to be the most promising platform for future application in clinical __proof of concept__ studies with novel PPAR agonist compounds in T2DM patients.In the studies comprising this thesis we evaluated the potential usefulness of cDNA microarray based gene expression profiling and 1H-NMR based metabolomics platforms as tools for the evaluation of novel PPAR_ and -_ agonists in future clinical __proof of concept studies__. We investigated the effects of rosiglitazone, (prototype PPAR_ agonist ) and ciprofibrate (prototype PPAR_ agonist) on global (target) tissue gene expression profiles and endogenous urinary and plasma metabolites of type 2 Diabetes Mellitus (T2DM) patients and healthy volunteers (HVs).The results from the transcriptomic analyses indicated that none of the genes in any of the tissues in either study group displayed a significant treatment response with either rosiglitazone of ciprofibrate vs. placebo at Bonferroni adjusted values and _=0.05. The results of the metabolomic analyses revealed significant rosiglitazone and ciprofibrate induced changes in endogenous urinary and plasma metabolite profiles of T2DM patients but not in HVs. We conclude that from the two molecular profiling platforms evaluated in this thesis, metabolomics currently appears to be the most promising platform for future application in clinical __proof of concept__ studies with novel PPAR agonist compounds in T2DM patients. Show less
The main objective of this thesis is to provide a conceptual framework for the use of Central Nervous System (CNS) biomarkers in early phase clinical drug development. In the Introduction the... Show moreThe main objective of this thesis is to provide a conceptual framework for the use of Central Nervous System (CNS) biomarkers in early phase clinical drug development. In the Introduction the current use of biomarkers in early CNS drug development is discussed. A conceptual framework for the classification of biomarkers is suggested, based on general questions that these markers should provide information on. The body of this thesis (Chapters 1-7) exemplifies the use of these markers within this conceptual framework. In the Conclusions and Discussion a critical evaluation of the presented conceptual biomarker framework is give and directions for future biomarker research are offered. Show less
