Synthesis of a novel nanocomposite containing chitosan as a three-dimensional printed wound dressing technique: Emphasis on gene expression

In this study, a highly porous three-dimensional (3D)-printed wound healing core/shell scaffold fabricated using poly-lactic acid (PLA). The core of scaffold was composed of hyaluronic acid (HA), copper carbon dots (Cu-CDs), rosmarinic acid, and chitosan hydrogel. Cu-CDs were synthesized using ammonium hydrogen citrate under hydrothermal conditions. Formulation containing 1 mg ml⁻¹concentration of Cu-CDs showed an excellent antibacterial activity against gram bacteria. At 0.25 mg ml⁻¹ of Cu-CDs concentration, scaffold had a good biocompatibility as confirmed by cytotoxicity assay on L929 fibroblast stem cells. in vivo wound healing experiments on groups of rats revealed that after 15 days of treatment, the optimal formulation of composite scaffold significantly improves the wound healing process compared to the PLA scaffold. This finding was confirmed by histological analysis and the relative expression of PDGF, TGF-β, and MMP-1 genes. The biocompatible antibacterial CU-CDS/PLA/HA/chitosan/rosmarinic acid nanocomposite is a promising wound healing scaffold which highly accelerates the process of skin regeneration.     

Nucleoside transport in mammalian cell membranes. III. Kinetic and chemical modification studies of cytosine-arabinoside and uridine transport in hamster cells in culture

Transport of the nucleoside analog cytosine-arabinoside (CAR) in transformed hamster cells in culture has been studied in conditions of minimal metabolic conversion. Uptake (zero-trans in) properties at 20 degrees C over a limited range of CAR concentrations were characterized by a Km of 350 micrometer and a maximal velocity (V) of 780 micrometer.min-1 (V/Km = 2.28 min-1). Equilibrium exhcange at 20 degrees C over a wider range of concentrations was best described by a saturable component with a Km of 500 micrometer and a v of 1230 micrometer.min-1 (V/Km = 2.26 min-1) and either a saturable component of high Km or a nonsaturable component of k = 0.3 min-1. For the saturable component, the v/Km values were similar in both procedures. CAR transport was inhibited by various metabolizable nucleosides. Uptake of some of these nucleosides was inhibited by CAR. CAR transport and uridine uptake were inhibited in a reversible but partially competitive fashion by high affinity probes like S-(p-nitrobenzyl-6-mercaptoinosine (NBMI) (Ki less than 0.5 nM) and in an irreversible fashion by SH reagents such as N-ethylmaleiimide (NEM). The organomercurial p-hydroxymercuribenzene sulfonate (pMBS) markedly stimulated transport of these nucleosides, but also markedly potentiated the inhibitory effects of either NBMI or NEM. The effects are interpreted either in terms of models which invoke allosteric properties or in terms of two transport systems which display distinct chemical susceptibilities to externally added probes.     

Distribution of Interdivisional Times In Proliferating and Differentiating Friend Murine Erythroleukaemia Cells

Abstract. The interdivisional times of Friend murine erythroleukaemia cells which are growing continuously, or during terminal erythroid differentiation after exposure to dimethyl sulphoxide (DMSO), were determined by time lapse video photography. the median interdivisional times were found to increase from 11.75 hr before exposure to DMSO, to 24.0 hr at 72 hr after exposure. This increase in median interdivisional time was accompanied by an increase in heterogeneity of interdivisional times (% CV = 8-5 → 40.8), by an increase in the similarity of sister interdivisional times (r_yy= 0.622 → 0.925), and by a decrease in the fraction of cells observed to divide ( F = 1. 0 → 0.807). Cells exposed to DMSO for 72 hr can be induced to divide at least once with nearly normal interdivisional times, if they are resuspended at a tenfold higher cell concentration. Computer simulations of cell cycle regulation, based on the opposing reactions model of Murphy, generate interdivisional time distributions which resemble the experimental data better than the single transition probability model of Smith and Martin.     

Iron stocks and risk of anemia in twins

This study aims to compare the risk of anemia by iron deficiency in mothers and infants of twin and single pregnancy. It concerned 33 couples of twins and 31 control, all 97 being term newborns. At birth, ferritinemia is significantly lower in twins, and reticulocytes count is significantly higher; their mothers have a significantly lower hemoglobin level and higher reticulocytes percentage and count. At 3 and 6 months, hemoglobin level and mean corpuscular hemoglobin are significantly lower in twins, as at 6 months ferritinemia is significantly lower in twins. Iron stocks constituted in utero are significantly lower in twin pregnancy, and this study support the early preventive iron treatment in twins.     

Inhibition of bacterial and human zinc-metalloproteases by bisphosphonate- and catechol-containing compounds

Compounds containg catechol or bisphosphonate were tested as inhibitors of the zinc metalloproteases, thermolysin (TLN), pseudolysin (PLN) and aureolysin (ALN) which are bacterial virulence factors, and the human matrix metalloproteases MMP-9 and −14. Inhibition of virulence is a putative strategy in the development of antibacterial drugs, but the inhibitors should not interfere with human enzymes. Docking indicated that the inhibitors bound MMP-9 and MMP-14 with the phenyl, biphenyl, chlorophenyl, nitrophenyl or methoxyphenyl ringsystem in the S₁′-subpocket, while these ringsystems entered the S₂′- or S₁ -subpockets or a region involving amino acids in the S₁′- and S₂′-subpockets of the bacterial enzymes. An arginine conserved among the bacterial enzymes seemed to hinder entrance deeply into the S₁′-subpocket. Only the bisphosphonate containing compound RC2 bound stronger to PLN and TLN than to MMP-9 and MMP-14. Docking indicated that the reason was that the conserved arginine (R203 in TLN and R198 in PLN) interacts with phosphate groups of RC2.