👤 MichielA J van de Sande

We interviewed 188 carriers (57.4% male; aged 43.0±15.0 years) on exercise participation since the age of 10 years. The exercise was quantified as the metabolic equivalent of task-h/wk before the presentation. MCE was defined as a composite of malignant ventricular arrhythmia (sustained ventricular tachycardia/fibrillation), heart failure (heart failure hospitalizations or transplantation), and septal reduction therapy. Static and dynamic exercises were defined per the Bethesda classification. Associations of exercise with MCE and cardiomyopathy penetrance were adjusted for sex and assessed using Cox regression. Overall, 43 (22.9%) subjects experienced MCE and 139 (73.9%) were diagnosed with cardiomyopathy. No association was found between overall physical activity and high-static activity with MCE ( Overall exercise participation does not generally increase the risk of adverse events among Show less

Fluorescence-guided surgery (FGS), based on fluorescent tracers binding to tumor-specific biomarkers, could assist surgeons to achieve complete tumor resections. This study evaluated potential biomarkers for FGS in pediatric Ewing sarcoma (ES). Immunohistochemistry (IHC) was performed to assess CD99, CXCR4, CD117, NPY-R-Y1, and IGF-1R expression in ES biopsies and resection specimens. LINGO-1 and GD2 evaluation did not work on the acquired tissue. Based on the immunoreactive scores, anti-CD99 and anti-CD117 were evaluated for binding specificity using flow cytometry and immunofluorescence microscopy. Anti-GD2, a tracer in the developmental phase, was also tested. These three tracers were topically applied to a freshly resected ES tumor and adjacent healthy tissue. IHC demonstrated moderate/strong CD99 and CD117 expression in ES tumor samples, while adjacent healthy tissue had limited expression. Flow cytometry and immunofluorescence microscopy confirmed high CD99 expression, along with low/moderate CD117 and low GD2 expression, in ES cell lines. Topical anti-CD99 and anti-GD2 application on ES tumor showed fluorescence, while anti-CD117 did not show fluorescence for this patient. In conclusion, CD99-targeting tracers hold promise for FGS of ES. CD117 and GD2 tracers could be potential alternatives. The next step towards development of ES-specific FGS tracers could be ex vivo topical application experiments on a large cohort of ES patients. Show less

Elevated nonfasting TG-rich lipoprotein levels are a risk factor for CVD. To further evaluate the relevance of LDL-receptor (LDLr) pathway and heparan sulfate proteoglycans (HSPGs) in TG homeostasis, we analyzed fasting and postprandial TG levels in mice bearing combined heterozygous mutations in both Exostosin (Ext) 1 and Ldlr, in subjects with hereditary multiple exostosis (HME) due to a heterozygous loss-of-function mutation in EXT1 or EXT2 (N = 13), and in patients with heterozygous mutations in LDLR [familial hypercholesterolemia (FH)] and SNPs in major HSPG-related genes (n = 22). Mice bearing a homozygous mutation in hepatic Ext1 exhibited elevated plasma TGs similar to mice lacking other key enzymes involved in HSPG assembly. Compound heterozygous mice lacking Ldlr and Ext1 showed synergy on plasma TG accumulation and postprandial clearance. In human subjects, a trend was observed in HME patients toward reduced postprandial TG clearance with a concomitant reduction in chylomicron clearance [area under the curve (AUC)-retinyl ester (RE) HME, 844 ± 127 vs. controls, 646 ± 119 nM/h, P = 0.09]. Moreover, in FH subjects with a high HSPG gene score, retinyl palmitate excursions were higher (AUC-RE, 2,377 ± 293 vs. 1,565 ± 181 nM/h, P < 0.05). Incremental AUC-apoB48 was similar between the groups. In conclusion, the data are supportive for a minor yet additive role of HSPG in human postprandial TG clearance, and further studies are warranted. Show less

Exotosin (EXT) proteins are involved in the chain elongation step of heparan sulfate (HS) biosynthesis, which is intricately involved in organ development. Loss of function mutations (LOF) in EXT1 and EXT2 result in hereditary exostoses (HME). Interestingly, HS plays a role in pancreas development and beta-cell function, and genetic variations in EXT2 are associated with an increased risk for type 2 diabetes mellitus. We hypothesized that loss of function of EXT1 or EXT2 in subjects with hereditary multiple exostoses (HME) affects pancreatic insulin secretion capacity and development. We performed an oral glucose tolerance test (OGTT) followed by hyperglycemic clamps to investigate first-phase glucose-stimulated insulin secretion (GSIS) in HME patients and age and gender matched non-affected relatives. Pancreas volume was assessed with magnetic resonance imaging (MRI). OGTT did not reveal significant differences in glucose disposal, but there was a markedly lower GSIS in HME subjects during hyperglycemic clamp (iAUC HME: 0.72 [0.46-1.16] vs. controls 1.53 [0.69-3.36] nmol·l-1·min-1, p<0.05). Maximal insulin response following arginine challenge was also significantly attenuated (iAUC HME: 7.14 [4.22-10.5] vs. controls 10.2 [7.91-12.70] nmol·l-1·min-1 p<0.05), indicative of an impaired beta-cell reserve. MRI revealed a significantly smaller pancreatic volume in HME subjects (HME: 72.0±15.8 vs. controls 96.5±26.0 cm3 p = 0.04). In conclusion, loss of function of EXT proteins may affect beta-cell mass and insulin secretion capacity in humans, and render subjects at a higher risk of developing type 2 diabetes when exposed to environmental risk factors. Show less

Heparanase is the major enzyme involved in degradation of endothelial heparan sulfates, which is associated with impaired endothelial nitric oxide synthesis. However, the effect of heparan sulfate chain length in relation to endothelial function and nitric oxide availability has never been investigated. We studied the effect of heterozygous mutations in heparan sulfate elongation genes EXT1 and EXT2 on endothelial function in vitro as well as in vivo. Flow-mediated dilation, a marker of nitric oxide bioavailability, was studied in Ext1(+/-) and Ext2(+/-) mice versus controls (n=7 per group), as well as in human subjects with heterozygous loss of function mutations in EXT1 and EXT2 (n=13 hereditary multiple exostoses and n=13 controls). Endothelial function was measured in microvascular endothelial cells under laminar flow with or without siRNA targeting EXT1 or EXT2. Endothelial glycocalyx and maximal arteriolar dilatation were significantly altered in Ext1(+/-) and Ext2(+/-) mice compared to wild-type littermates (glycocalyx: wild-type 0.67±0.1 μm, Ext1(+/-) 0.28±0.1 μm and Ext2(+/-) 0.25±0.1 μm, P<0.01, maximal arteriolar dilation during reperfusion: wild-type 11.3±1.0%), Ext1(+/-) 15.2±1.4% and Ext2(+/-) 13.8±1.6% P<0.05). In humans, brachial artery flow-mediated dilation was significantly increased in hereditary multiple exostoses patients (hereditary multiple exostoses 8.1±0.8% versus control 5.6±0.7%, P<0.05). In line, silencing of microvascular endothelial cell EXT1 and EXT2 under flow led to significant upregulation of endothelial nitric oxide synthesis and phospho-endothelial nitric oxide synthesis protein expression. Our data implicate that heparan sulfate elongation genes EXT1 and EXT2 are involved in maintaining endothelial homeostasis, presumably via increased nitric oxide bioavailability. Show less