👤 Jarne De Paepe

G-quadruplexes (G4s) are non-canonical secondary nucleic acid structures with important biological implications in telomere elongation and gene expression. A large number of small molecules have been developed to bind and even covalently target these structures, enhancing the potency and duration of binding. Alternatively, peptide-based ligands have been studied and shown to offer several advantages, including high specificity, a modular design, and ease of synthesis. In this work, we describe a peptide-based methodology for covalent G4-targeting, based on the introduction of two photoactivatable moieties in a peptide derived from the RHAU helicase. Rational insertion of crosslinkers at different positions yielded nine different peptides, which were evaluated for their G4-stabilizing effect and alkylation potential. Moderate to high alkylation yields towards G4s were obtained. The G4 stabilizing potential drastically increased for N-terminal modifications of the RHAU18 peptide. This led to the design of a further series of peptides with varying N-terminal residues to gain insight in the stabilization potential of each single amino acid modification and provided a comprehensive study of the binding behaviour of modified RHAU peptides. Show less

Ageing endurance athletes have a higher prevalence of coronary artery disease (CAD) on coronary CT angiography (CCTA) than healthy controls, despite similarly low conventional cardiovascular risk. The predictive value of lipoprotein(a) [Lp(a)] for CAD in these low-risk individuals remains unclear. The Master@Heart study included 558 men (aged 45-70 years) without known cardiovascular risk factors: 191 lifelong athletes, 191 late-onset athletes, and 176 healthy controls. CCTA assessed coronary artery calcification (CAC) and plaques. The association between Lp(a) and subclinical CAD was assessed using logistic regression analysis to estimate odds ratios (ORs), adjusted for cardiovascular risk factors. Lp(a) was analysed dichotomously (<125 vs. >125 nmol/L) and continuously (per 10 nmol/L increase). 76 participants (13.6%) had elevated Lp(a) levels (>125 nmol/L). Elevated Lp(a) was significantly associated with age-specific CAC percentile≥75 (OR 1.80, p=0.049) and ≥1 mixed plaque (OR 1.76, p=0.046). Other CAD measures all tended to be more prevalent in those with elevated Lp(a). In the continuous analysis, Lp(a) was significantly associated with CAC>100 (OR 1.03, p=0.045), CAC percentile≥75 (OR 1.04, p=0.014), and ≥1 mixed or non-calcified plaque (OR 1.03, p=0.029).Lp(a) and prevalence of elevated Lp(a) were similar across lifelong athletes, late-onset athletes, and controls (p=0.586 and p=0.724, respectively). No significant interaction was found between Lp(a) and the exercise groups in predicting CAD. Lp(a) is independently associated with subclinical CAD in ageing endurance athletes and healthy controls, despite similarly low conventional cardiovascular risk. Lp(a) does not explain the higher CAD prevalence in lifelong athletes compared to controls, but may enhance risk stratification in this low-risk population. Show less

Hot-melt extrusion is an option to fabricate amorphous solid dispersions and to enhance oral bioavailability of poorly soluble compounds. The selection of suitable polymer carriers and processing aids determines the dissolution, homogeneity and stability performance of this solid dosage form. A miniaturized extrusion device (MinEx) was developed and Hypromellose acetate succinate type L (HPMCAS-L) based extrudates containing the model drugs neurokinin-1 (NK1) and cholesterylester transfer protein (CETP) were manufactured, plasticizers were added and their impact on dissolution and solid-state properties were assessed. Similar mixtures were manufactured with a lab-scale extruder, for face to face comparison. The properties of MinEx extrudates widely translated to those manufactured with a lab-scale extruder. Plasticizers, Polyethyleneglycol 4000 (PEG4000) and Poloxamer 188, were homogenously distributed but decreased the storage stability of the extrudates. Stearic acid was found condensed in ultrathin nanoplatelets which did not impact the storage stability of the system. Depending on their distribution and physicochemical properties, plasticizers can modulate storage stability and dissolution performance of extrudates. MinEx is a valuable prototyping-screening method and enables rational selection of plasticizers in a time and material sparing manner. In eight out of eight cases the properties of the extrudates translated to products manufactured in lab-scale extrusion trials. Show less

MLLT10 (previously called AF10) is a moderately common MLL fusion partner predominantly occurring in acute monoblastic leukemia (AML-M5). 10;11 rearrangements require at least three breaks in order to generate an in-frame MLL-MLLT10 fusion as a result of the opposite orientations of both genes on the respective chromosome arms. In this study, we describe a detailed molecular cytogenetic analysis of MLL-MLLT10 positive 10;11 rearrangements in two patients. We observed an as yet unreported chromosomal mechanism with at least four breakpoints, leading to MLL-MLLT10 gene fusion in a 24-year-old male. An inversion of 11q13-q23 with a breakpoint in the MLL gene was followed by an additional break 3' of MLL prior to insertion of the 11q segment into MLLT10. In a second patient, a 37-year-old male with AML-M5b, molecular cytogenetic analysis of an apparent 10;11 reciprocal translocation showed an intrachromosomal inversion of 3'MLLT10followed by a reciprocal translocation between 10p12 and 11q23. Review of the literature showed that all cases were the result of an inversion of either 10p or 11q followed by translocation 10p;11q or insertion of the inverted segment into MLLT10 or MLL. Show less