Human endothelial cell growth and phenotypic expression on three dimensional poly(lactide-co-glycolide) sintered microsphere scaffolds for bone tissue engineering

Bone tissue engineering offers promising alternatives to repair and restore tissues. Our laboratory has employed poly(lactide-co-glycolide) PLAGA microspheres to develop a three dimensional (3-D) porous bioresorbable scaffold with a biomimetic pore structure. Osseous healing and integration with the surrounding tissue depends in part on new blood vessel formation within the porous structure. Since endothelial cells play a key role in angiogenesis (formation of new blood vessels from pre-existing vasculature), the purpose of this study was to better understand human endothelial cell attachment, viability, growth, and phenotypic expression on sintered PLAGA microsphere scaffold. Scanning electron microscopy (SEM) examination showed cells attaching to the surface of microspheres and bridging the pores between the microspheres. Cell proliferation studies indicated that cell number increased during early stages and reached a plateau between days 10 and 14. Immunofluorescent staining for actin showed that cells were proliferating three dimensionally through the scaffolds while staining for PECAM-1 (platelet endothelial cell adhesion molecule) displayed typical localization at cell-cell contacts. Gene expression analysis showed that endothelial cells grown on PLAGA scaffolds maintained their normal characteristic phenotype. The cell proliferation and phenotypic expression were independent of scaffold pore architecture. These results demonstrate that PLAGA sintered microsphere scaffolds can support the growth and biological functions of human endothelial cells. The insights from this study should aid future studies aimed at enhancing angiogenesis in three dimensional tissue engineered scaffolds.     

Dosimetric effect of limited aperture multileaf collimator on VMAT plan quality: A study of prostate and head-and-neck cancers

Aim

The aim of study was to evaluate the dosimetric effect of collimator-rotation on VMAT plan quality, when using limited aperture multileaf collimator of Elekta Beam Modulator? providing a maximum aperture of 21 cm × 16 cm.

Thermo-mechanical properties of cubic titanium nitride

The equilibrium structure, elastic constants C_ij and thermodynamic functions of cubic titanium nitride (TiN) were calculated within the temperature range of 0–3100 K and under a pressure range 0–60 GPa. Properties were computed using the generalised gradient approximations (GGA) exchange-correlation functional. Calculated mechanical properties (Elastic constants, Young’s modulus and shear modulus) and phonon spectra of TiN obtained via robust DFT-QHA algorithm, were generally in a good agreement with available experimental and theoretical analogous values. In particular, a well-examined quasi-harmonic approximation method implemented in the Gibbs2 code is utilised herein to provide accurate estimation of thermal expansion coefficients, entropies, heat capacity values (at different combinations of temperature/volume/pressure) and Debye’s temperature. Parameters calculated herein shall be useful to elucidate the superior performance of TiN at harsh operational conditions encompassing elevated temperatures and pressures pertinent to cutting machineries and surface coatings.     

Synthesis,structure-activity relationship and molecular docking studies of 3-O-flavonol glycosides as cholinesterase inhibitors

The prime objective of this research work is to prepare readily soluble synthetic analogues of naturally occurring 3-O-flavonol glycosides and then investigate the influence of various substituents on biological properties of synthetic compounds. In this context, a series of varyingly substituted 3-O-flavonol glycosides have been designed, synthesized and characterized efficiently. The structures of synthetic molecules were unambiguously corroborated by IR, ¹H, ¹³C NMR and ESI-MS spectroscopic techniques. The structure of compound 22 was also analyzed by X-ray diffraction analysis. All the synthetic compounds (21–30) were evaluated for in vitro inhibitory potential against cholinesterase enzymes. The results displayed that most of the derivatives were potent inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with varying degree of IC₅₀ values. The experimental results were further encouraged by molecular docking studies in order to explore their binding behavior with the active pocket of AChE and BChE enzymes. The experimental and theoretical results are in parallel with one another.