Evaluation of a new commercial Clostridium difficile toxin A enzyme immunoassay using diarrhoeal stools.

A new, commercially available enzyme immunoassay for the detection of toxin A in stool specimens, the Premier Clostridium difficile Toxin A test (Meridian Diagnostics), was evaluated using 228 diarrhoeal stool specimens. Using a cytotoxin assay on HeLa cells as the reference method, this new test resulted in a sensitivity of 88% and a specificity of 95%. Using the presence or absence of a toxigenic strain in the stools as the reference method, the sensitivity was similar to that of the cytotoxin assay (71.7+ versus 70.5%) and the overall correlation was even better (89.4% versus 82%). The Premier Clostridium difficile Toxin A assay is rapid and easy to perform and is an excellent alternative to the usual toxin B assay

SOLUBLE BIMETALLIC mu -OXOALKOXIDES - 9. epsilon -CAPROLACTONE AND beta -PROPIOLACTONE BLOCK COPOLYMERIZATION.

peer reviewedaudience: researcherThe fast and living ring-opening polymerization of lactones by bimetallic mu -oxoalkoxides in homogeneous organic phase has led to successful block copolymerization. The catalyst is coordinatively associated in organic media; however, interaction with lactones can induce, following their nature, different rearrangements of the catalytic aggregates, depending on the nature of these lactones. Consequently, epsilon -caprolactone and beta -propiolactone block copolymers are quantitatively obtained only in the presence of a completely dissociated catalyst

Soluble bimetallic μ-oxo-alkoxides. 8. Structure and kinetic behavior of the catalytic species in unsubstituted lactone ring-opening polymerization

The bimetallic µ-oxo-alkoxides are highly active for lactone ring-opening polymerization. These compounds are aggregated in solution and their mean degree of association depends on the nature of alkoxide groups, metals, and solvent; it is modified by addition of suitable ligands or temperature variations. The course of the lactone polymerization is strongly related to the structural features of the catalyst. The determination of the mean number of growing chains per catalyst molecule, the study of the polymerization kinetics, and the knowledge of the catalyst behavior during the monomer conversion have contributed to an understanding of the polymerization mechanism

NEW PROSPECTS IN HOMOGENEOUS RING-OPENING POLYMERIZATION OF HETEROCYCLIC MONOMERS.

audience: researcherSince the early days of ring-opening polymerization of oxirane and related monomers, many initiators have been described for this type of chain reaction, belonging respectively to acid-base, ionic, and coordination catalysis. In particular, it has been shown that the highly active coordination type initiators are the only ones able to promote the ring-opening polymerization of methyloxirane (propylene oxide, PO) to high molecular weight, and eventually stereoregular polyethers. In the reported experiments a new family of ring-opening polymerization catalysts, namely bimetallic mu -oxoalkoxides, were prepared and used in the study of mechanisms of ring-opening polymerization. It is concluded that the good control and knowledge of these oxoalkoxides structures have led to a better understanding of the key factors governing the ring-opening polymerization processes; the results emphasize dramatically the determinant influence of the association phenomena in the catalytic species. They have also promoted the discovery of new phenomena (like the topochemical controls of the chains formation), and of new synthesis methods (for the block copolymers), which could most probably be extended to more classical catalysts. These species constitute a very promising tool for many problems in polymer and general chemistry

Etude des proprietes chimiques et catalytiques d'agregats μ-oxo et μ-alcoxy polynucleaires

peer reviewed[No abstract available