Dynamics of quasicontinuous systems

Quasicontinuous functions are continuous on a residual subset of their domain. The class includes many standard examples from dynamical systems, including the baker transformation and interval exchange maps. We present standard results of continuous topological dynamics (such as that sensitive dependence follows from transitivity and dense periodic points) which extend to quasicontinuous dynamics     

Iloprost Attenuates Oxidative Stress-Dependent Activation of Collagen Synthesis Induced by Sera from Scleroderma Patients in Human Pulmonary Microvascular Endothelial Cells

Endothelial cell injury is an early event in systemic sclerosis (SSc) pathogenesis and several studies indicate oxidative stress as the trigger of SSc-associated vasculopathy. Here, we show that circulating factors present in sera of SSc patients increased reactive oxygen species (ROS) production and collagen synthesis in human pulmonary microvascular endothelial cells (HPMECs). In addition, the possibility that iloprost, a drug commonly used in SSc therapy, might modulate the above-mentioned biological phenomena has been also investigated. In this regard, as compared to sera of SSc patients, sera of iloprost-treated SSc patients failed to increased ROS levels and collagen synthesis in HPMEC, suggesting a potential antioxidant mechanism of this drug.     

Control of alkali-metal oxide activity in molten silicates

A new thermochemical reactor is designed to control alkali-metal oxide activity simultaneously in several molten silicates at temperature up to 1400 °C. The method consists in imposing an alkali metal vapor pressure in a closed system by Na_(g) evaporation from Na₂O–xSiO₂ melt and equilibrating this vapor with the molten silicate samples. By comparison of experiments carried out in regular furnaces, the drastic reduction of the working volume ensures a better control of sodium metal vapor pressure for durations of the order of a hundred of hours. This device has been applied to measuring the sodium solubility and sodium-metal oxide activity at 1350 °C in the anorthite–diopside eutectic melt composition of the CaO–MgO–Al₂O₃–SiO₂ system.     

Shear stresses in elastic beams: an intrinsic approach

The theory of non-uniform flexure and torsion of Saint-Venant's beam with arbitrary multiply connected cross section is revisited in a coordinate-free form to provide a computationally convenient context. Numerical implementations, by Matlab, are performed to evaluate the maximum elastic shear stresses in beams with rectangular cross sections for different Poisson's ratios. The deviations between the maximum and mean stresses are then diagrammed to adjust the results provided by Jourawski's method.     

A cationic Zn(II) porphyrazine induces a stable parallel G-quadruplex conformation in human telomeric DNA

A water soluble Zn(II) porphyrazine drives the conformational equilibrium of the G-quadruplex of a human telomeric sequence exclusively towards a parallel conformation upon complexation.     

Determination of Hyaluronic Acid in a Chitosan-Based Formulation by RP C18 and HILIC LC–ESI-MS: an Evaluation of Matrix Effect

Two simple and fast C18 and HILIC liquid chromatography–electrospray mass spectrometry methods for the determination of hyaluronic acid (HA) in a mucoadhesive chitosan-based formulation were developed and validated. The performances of both methods were compared in terms of validation parameters and matrix effect. A simple sample preparation method based on sulphuric acid-based degradation was optimized for the detection of HA fragments (i.e. m/z 380 2-mer, m/z 759 4-mer, m/z 1,138 8-mer and m/z 1,518 16-mer). By operating under selected ion-monitoring mode, excellent selectivity towards chitosan fragments was obtained. For validation, good linearity, detection limits (<4 μg mL^?1) and precision (RSD % < 16 %) were generally obtained on matrix with both columns. However, HILIC column exhibited improved performances in terms of HA fragment separation and selectivity. By analyzing on the C18 column the chitosan-based formulation and sample extracts from pig mucosa treated with the formulation, matrix effects exhibited a dependence of signal suppression degree (ranging from 37 to 83 %) as a function of the HA fragment dimension. The HILIC column afforded instead a significantly reduced suppression degree (ranging from 1 to 16 %) and a better separation. These findings demonstrated the improved performances of the HILIC column with respect to conventional C18 mechanism for the analysis of HA fragments in complex matrices.     

Structure–Activity Relationship Study of a Potent α-Thrombin Binding Aptamer Incorporating Hexitol Nucleotides

The replacement of one or more nucleotide residues in the potent α-thrombin-binding aptamer NU172 with hexitol-based nucleotides has been devised to study the effect of these substitutions on the physicochemical and functional properties of the anticoagulant agent. The incorporation of single hexitol nucleotides at the T9 and G18 positions of NU172 substantially retained the physicochemical features of the parent oligonucleotide, as a result of the biomimetic properties of the hexitol backbone. Importantly, the NU172- T ^H9 mutant exhibited a higher binding affinity toward human α-thrombin than the native aptamer and an improved stability even after 24 h in 90 % human serum, with a significant increase in the estimated half-life. The anticoagulant activity of the modified oligonucleotide was also found to be slightly preferable to NU172. Overall, these results confirm the potential of hexitol nucleotides as biomimetic agents, while laying the foundations for the development of NU172-inspired α-thrombin-binding aptamers.