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Biomedical subjects

M Blandin

Publications and source records attributed to M Blandin.

12 recordsLinked to original sources
PubMed1983

Use of methylphosphonic dichloride for the synthesis of oligonucleoside methylphosphonates.

Methylphosphonic dichloride was used to prepare protected deoxyribonucleoside 3'-methylphosphonate beta-cyanoethyl esters, d-[(MeO)2Tr]NpCNEt, and protected oligonucleoside methylphosphonates in solution. Reaction of d-[(MeO)2Tr]N with methylphosphonic dichloride gives d-[(MeO)2Tr]NpCl. The phosphonylation and subsequent esterification or condensation reactions are each complete within 60 min. The products are readily purified by "flash chromatography" on silica gel columns. d-[(MeO)2Tr]NpCl, or its tetrazole derivative, d-[(MeO)2Tr]Nptet, were tested as intermediates for the synthesis of oligothymidine methylphosphonates on a silica gel polymer support. The average yield per coupling step was 76% and did not increase with addition of more d-[(MeO)2Tr]TpCl. The formation of (5'-5') linked thymidine dimers indicated that the thymidine monomers are clustered closely together on the support. When N is ibuG, the yield for the coupling step on the support is very low. This may be due to steric hindrance of the 3'-phosphonate group by the N-2 isobutryl protecting group.

Indicators and Reagents↗
PubMed1977

Poly-2'-deoxy-2'-fluoro-cytidylic acid: enzymatic synthesis, spectroscopic characterization and interaction with poly-inosinic acid.

The polymerization of 2'deoxy-2'-fluoro-cytidine-diphosphate (dCflDP) by polynucleotide phosphorylase is barely detectable in the presence of Mg++ under usual experimental conditions for polymerization of nucleoside diphosphates. High concentrations of enzyme have to be used to accomplish the synthesis. Mn++ is a better activator than Mg++ for the reaction. cCflDP inhibits the polymerization of CDP and has a Km=8.8X10-3M, six times higher than CDP.- The polymer, poly (dCfl), ressembles in many respects poly(C), but not poly(dC): the acid selfstructure forms at similar pK's; interaction with poly(I) yields a 1:1 complex the CD spectrum of which is similar to that of poly(I).poly(C). Finally, the Tm's of poly(I).poly(dCfl) are comparable to those of poly(I).poly(C).

Circular Dichroism↗
PubMed1974

Nucleoside conformations. XVII. A PMR study of 2'-anhydronucleosides and comparison with X-ray data.

A series of 2'-cyclo-nucleosides (2,2'-O-anhydro-uridine, -N(3)-uridine and cytidine and 8,2'-S-anhydro-guanosine) have been studied by PMR in DMSO and D(2)O. As expected these compounds are quite rigid, but their solution conformation is considerably different from that observed in single crystal x-ray studies. While the pyrimidine cyclonucleosides in the crystal form show a C(4')-endo conformation (pseudorotational phase angle P=212 degrees to 233 degrees ), their solution conformation is C(1')-exo (P=130 degrees to 138 degrees ) and the cyclothioguanosine shows a closely similar one (P=112 degrees ). Exocyclic rotamer distribution is different in the various compounds.

Crystallography, X-Ray↗
PubMedDate not supplied

Enzymatic polymerization of 5-mercuriuridine-5'-diphosphate with polynucleotide phosphorylase from E. coli.

We report the polymerization of 5-mercuriuridine-5'-diphosphate (ppUHgX), in the presence of an excess of beta-mercaptoethanol, with polynucleotide phosphorylase from E. coli. A degradation of mercurated nucleotides with mercaptans was observed and about 30% of incorporation of mercury in the polymer was obtained after treatment with pancreatic RNase. The influence of ppUHgX and pUHgX with or without beta-mercaptoethanol was also studied on the polymerization of UDP. The ppUHgX did not polymerize in the absence of beta-mercaptoethanol.

Chromatography, Thin Layer↗
PubMedDate not supplied

[Original technique for secondary impressions in complete removable dentures (CRD)].

Regardless of its anatomic shape, an edentulous arch is formed by two types of mucosa, different in both nature and behavior. This is why the impression of such a complex requires two distinct steps with two different modeling materials with different consistency. The first step is the border molding of the mucosal reflexion zone with a silicone of medium viscosity, placed on the borders of the custom tray. The second step is the static impression of the inner part of the denture, with a fluid or very fluid silicone.

Dental Impression Technique↗