Mapping density, diversity and species-richness of the Amazon tree flora

Using 2.046 botanically-inventoried tree plots across the largest tropical forest on Earth, we mapped tree species-diversity and tree species-richness at 0.1-degree resolution, and investigated drivers for diversity and richness. Using only location, stratified by forest type, as predictor, our spatial model, to the best of our knowledge, provides the most accurate map of tree diversity in Amazonia to date, explaining approximately 70% of the tree diversity and species-richness. Large soil-forest combinations determine a significant percentage of the variation in tree species-richness and tree alpha-diversity in Amazonian forest-plots. We suggest that the size and fragmentation of these systems drive their large-scale diversity patterns and hence local diversity. A model not using location but cumulative water deficit, tree density, and temperature seasonality explains 47% of the tree species-richness in the terra-firme forest in Amazonia. Over large areas across Amazonia, residuals of this relationship are small and poorly spatially structured, suggesting that much of the residual variation may be local. The Guyana Shield area has consistently negative residuals, showing that this area has lower tree species-richness than expected by our models. We provide extensive plot meta-data, including tree density, tree alpha-diversity and tree species-richness results and gridded maps at 0.1-degree resolution

Marfan syndrome: The complex road to an optimal treatment strategy

Marfan syndrome (MFS) is a heritable connective tissue disorder affecting the ocular, skeletal and cardiovascular system. The management of patients with MFS requires a multidisciplinary approach, and includes physical symptoms, as well as psychological factors. Optimal long-term outcome in patients with MFS is mainly focused on slowing down the aortic root dilatation rate, and to prevent aortic complications. It demands lifelong follow-up, with imaging of the aortic root at regular intervals, and in many patients lifelong pharmacological treatment, and surgery at young age. It is however intriguing that in this era of drug development, no pharmacological treatment strategy has been identified that can inhibit aortic disease in patients with MFS. Therefore, the main objective of this thesis is to obtain more insight into a novel pharmacological strategy. Furthermore, it is of great importance to establish parameters that could help to determine aortic disease severity in patients with MFS, in order to provide an optimal treatment strategy for individual patients. In that light we also aim to obtain more insight into biomarkers that potentially, identify patients at high risk for aortic complications

Marfan syndrome: The complex road to an optimal treatment strategy

Marfan syndrome (MFS) is a heritable connective tissue disorder affecting the ocular, skeletal and cardiovascular system. The management of patients with MFS requires a multidisciplinary approach, and includes physical symptoms, as well as psychological factors. Optimal long-term outcome in patients with MFS is mainly focused on slowing down the aortic root dilatation rate, and to prevent aortic complications. It demands lifelong follow-up, with imaging of the aortic root at regular intervals, and in many patients lifelong pharmacological treatment, and surgery at young age. It is however intriguing that in this era of drug development, no pharmacological treatment strategy has been identified that can inhibit aortic disease in patients with MFS. Therefore, the main objective of this thesis is to obtain more insight into a novel pharmacological strategy. Furthermore, it is of great importance to establish parameters that could help to determine aortic disease severity in patients with MFS, in order to provide an optimal treatment strategy for individual patients. In that light we also aim to obtain more insight into biomarkers that potentially, identify patients at high risk for aortic complications

Abnormal aortic hemodynamics are associated with risk factors for aortic complications in patients with marfan syndrome

Background: It is difficult to assess the risk for aortic dissection beyond the aortic root in patients with Marfan syndrome (MFS). To aid risk assessment in these patients, we investigated aortic flow and wall shear stress (WSS) by 4D flow magnetic resonance imaging (MRI) in patients with MFS and compared the results with healthy volunteers. We hypothesized that MFS patients with a high-risk profile for aortic dissection would show abnormal hemodynamics in aortic regions associated with aortic dissection.Methods: MFS patients (n = 55) and healthy subjects (n = 25), matched for age and sex, prospectively underwent 4D flow MRI. 4D flow maps were constructed to detect elevated (defined as higher than the three-dimensional 95 % confidence interval) and deviant directed (defined as vector angle differences higher than 120) WSS in MFS patients as compared to the controls. Univariate and multivariate associations with risk factors for aortic dissection in MFS patients were assessed.Results: The maximum incidence for elevated WSS was 20 % (CI 9 %-31 %) and found in the ascending aorta. The maximum for deviant directed WSS was 39 % (CI 26 %-52 %) and found in the inner descending aorta. Significantly more male patients had deviant directed WSS in the inner proximal descending aorta (63 % vs 24 %, p = 0.014). Multivariate analysis showed that deviant directed WSS was associated with male sex (p = 0.019), and a haplo-insufficient FBN1 mutation type (p = 0.040). In 60 % of MFS patients with a previous aortic root replacement surgery, abnormal hemodynamics were found in the ascending aorta. No significant differences between hemodynamics were found in the descending aorta between operated and non-operated patients.Conclusion: Deviant directed WSS in the proximal descending aorta is associated with known risk factors for aortic dissection in MFS patients, namely male sex and a haploinsufficient FBN1 mutation type

A cross-sectional study on fatigue, anxiety, and symptoms of depression and their relation with medical status in adult patients with Marfan syndrome. Psychological consequences in Marfan syndrome

Marfan syndrome (MFS) is a connective tissue disorder affecting the cardiovascular, ocular, and skeletal system, which may be accompanied by psychological features. This study aimed to determine the prevalence of fatigue, anxiety, and symptoms of depression in MFS patients, and to assess the degree to which sociodemographic and clinical variables are associated with fatigue and psychological aspects. The prevalence of fatigue, anxiety, and symptoms of depression were assessed in two cohorts of MFS patients and compared with healthy controls. The checklist individual strength (CIS), and hospital anxiety and depression scale (HADS) questionnaires were utilized. Medical status was assessed (family history of MFS, aortic root dilatation >40 mm, previous aortic surgery, aortic dissection, chronic pain, skeletal involvement, and scoliosis). Severe fatigue was experienced by 37% of the total MFS cohort (n = 155). MFS patients scored significantly higher on the CIS questionnaire, concerning severe fatigue, as compared with the general Dutch population (p < 0.0001). There were no differences in HADS anxiety or depression scores. In older MFS patients, with a more severe cardiovascular phenotype, chronic pain, and a higher unemployment rate, significantly more symptoms of depression were observed, when compared with the general population (p = 0.027) or compared with younger MFS patients (p = 0.026). Multivariate analysis, showed that anxiety was associated with chronic pain (p = 0.022) and symptoms of depression with unemployment (p = 0.024). MFS patients report significantly more severe fatigue as compared with the general population. Since the cause of fatigue is unclear, more research may be needed. Psychological intervention, for example, cognitive behavioral therapy, may contribute to a reduction in psychological symptoms