Biomedical subjects

Delphine Machy

Publications and source records attributed to Delphine Machy.

3 recordsLinked to original sources

PubMed2004

Alpha-L-fucosidases: exoglycosidases with unusual transglycosylation properties.

Apha-LFucosidases (EC 3.2.1.51), the only members of the CAZy family GH-29, are widespread glycosidases involved in many biological processes including inflammation, metastasis, and the lysosomal storage disease fucosidosis. Despite their biological significance, information concerning the mechanism of alpha-Lfucosidases has only recently become available. In an attempt to obtain further data concerning their mechanism, we have investigated the hydrolytic and transglycosylation properties of a canine and a mollusk (Pecten maximus) alpha-Lfucosidase. Our results show that, despite the evolutionary distance between these two species, both enzymes have similar hydrolysis and transglycosylation properties. Surprisingly, we found that, starting from monosaccharides, these exoglycosidases were able to catalyze efficiently the synthesis of highly branched fuco-oligosaccharides as large as tetrasaccharides, a unique feature for a wild-type exoglycosidase. The structural analysis of the compounds formed revealed that the regioselectivity of alpha-Lfucosidases is strongly influenced by the structure of the acceptor. This leads us to propose an enzymatic approach for the preparative synthesis of fuco-oligosaccharides. This will not only allow the synthesis of biological determinants containing fucose but also of new fucose-containing oligosaccharides as alpha-glycosynthases appear to be difficult to obtain.

Animals↗

PubMed2002

Heparin and non-heparin-like dextrans differentially modulate endothelial cell proliferation: in vitro evaluation with soluble and crosslinked polysaccharide matrices.

Proliferation of endothelial cells (ECs) is a cellular step of particular importance for implanted cardiovascular biomaterials. Heparin and some synthetic water-soluble non-anticoagulant polysaccharides derived from dextran and bearing anionic carboxymethyl and hydrophobic benzylamine groups were first investigated for their effects on EC proliferation in vitro. The results assessed by cell counting, 3H-thymidine uptake, and flow cytometry analysis, showed that the derivatized dextran-bearing hydrophobic groups stimulated the EC growth in the presence of serum, whereas native dextran or dextran-bearing anionic carboxymethyl groups were inactive and heparin was slightly inhibitory. Then, we showed that the derivatized dextran enhanced EC proliferation by potentiation of the mitogenic activities of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (FGF-2), two potent EC growth factors. In the presence of 2 nM of derivatized dextran, a 3-fold and 13-fold increase of 3H-thymidine uptake was obtained with VEGF and FGF-2, respectively. Finally, proliferation of ECs was investigated on crosslinked gels made of polysaccharides. It is of interest that EC proliferation was higher on gels containing the derivatized dextran than on plain hydrogels, and heparinized gels inhibited cell proliferation. From the obtained results, we propose that the synthetic non-heparin-like dextran may be of interest as a coating for the endothelialization of cardiovascular biomaterials.

Anticoagulants↗

PubMed2002

A new vascular polyester prosthesis impregnated with cross-linked dextran.

It is essential that a synthetic vascular graft is preclotting prior to implantation in order to prevent blood leaking through the graft wall. We have impregnated a knitted polyester prosthesis with cross-linked dextran. The aim of this study was to develop a process for obtaining an impervious prosthesis and to compare the characteristics of this dextran-impregnated graft with those of a commercially available collagen-impregnated graft. This new vascular prosthesis was coated with dextran; sodium trimetaphosphate was utilized as the cross-linking agent. In an attempt to determine the optimal conditions for impregnation, the dynamic viscosity of the dextran solution was measured during the cross-linking reaction. The results suggest that the dynamic viscosity is correlated with the concentrations of dextran, sodium hydroxide, and sodium trimetaphosphate. The effect of temperature on the dynamic viscosity was also investigated. The water permeability, the coating weight, and the structure of the dextran-impregnated graft were compared with those of a collagen-impregnated prosthesis. The water permeability of the vascular grafts was reduced by dextran impregnation, from 1010 ml/min per cm2 for the control to 0.04 ml/min per cm2 under standard testing conditions. The dextran coating is capable of rendering the graft impervious to water. The coating weight of the graft treated with dextran was approximately the same as the weight of the collagen-impregnated graft. Finally, the morphology of the prosthetic wall was analyzed using scanning electron microscopy. The promotion of endothelial cell recovery was only observed for the polyester grafts treated with dextran or collagen.

Blood Vessel Prosthesis↗