[Which prostheses to use in mesh sacrocolpopexy? Experimental and clinical study]. / Promontofixation : quelles prothèses choisir ? Étude expérimentale et clinique.

BACKGROUND: Sacrocolpopexy is the standard surgical treatment of genital prolapse of the upper vaginal wall. Nowadays, the laparotomy approach is progressively supplanted by the laparoscopic procedure for the same anatomical results. About sacrocolpopexy, to date it still remains details of the technique, which differ with surgical teams maintaining controversy. Among them, the choice of the meshes certainly creates debate. OBJECTIVES: To state the basic physicochemical principles which are necessary for surgeons to select the most suitable prosthetic material to obtain the most beneficial anatomic and functional outcomes for patients. MATERIAL AND METHODS: The concepts of prosthetic biocompatibility, strength, shrinkage, deformation and elasticity are discussed. They are illustrated by experimental animal references and also human clinical references. RESULTS: Macroporous polypropylene and polyester prostheses (pore size>1 mm) are properly integrated. Collagen prosthetic coating improves tissue integration. Absorbable and nonabsorbable ultralight prostheses expose patients to a high risk of recurrence. Multifilament polyester wide pore-side prostheses have less retraction and are more flexible than monofilament polypropylene prostheses. DISCUSSION AND CONCLUSION: The prosthetic cut-off weight below which the mesh does not offer any guarantee of strength is not precisely known. Moreover, the benefit of weight reduction is not proved. Currently, heavy weight multifilament polyester prostheses with wide pore size, more than 1mm, appear to be the most appropriate meshes for sacrocolpopexy without vaginal incision.

The influence of isocyanurate content on the bioperformance of hydrocarbon-based polyurethanes.

Bulk, surface and bioactivity of newly synthesized hydroxy telechelic polyisoprene-based (H-HTPI) polyurethane were investigated by means of ATR-FT-IR, contact-angle measurements, cell viability, calcification, and platelet and fibrinogen quantification. The influence of isophorone diisocyanates isocyanurate (I-IPDI) content on these properties was determined. Results generally showed a non-significant difference in these properties when they were compared with a commercially available biomedical polyurethane (PU), such as Tecoflex. Unexpectedly, where the increase of isocyanate content for commercial diisocyanate-based biocompatible PU significantly increases the surface contact angle, the new hydroxy telechelic polyisoprene-based PU showed a decrease of water contact angle with increasing I-IPDI content in the polymer. Nevertheless, the overall surface exhibited hydrophobic properties, i.e., theta > 85. Polymer cytotoxicity, assessed with L929 cell line in direct contact with the surface of the samples, showed no toxic effects on the cells. Interestingly, regardless of the I-IPDI content, platelet adhesion and fibrinogen adsorption, as well as the mineral deposition were fairly similar for all synthesized PUs. Our findings revealed that replacing diisocyanates by their isocyanurate homologues is a very relevant approach for preparation of polyurethanes with different mechanical properties while maintaining similar surface properties.

In vitro thrombogenicity investigation of new water-dispersible polyurethane anionomers bearing carboxylate groups.

New segmented polyurethane (PU) anionomers based on hydroxytelechelic polybutadiene were synthesized via an aqueous dispersion process. Incorporation of carboxylic groups was achieved using thioacids of different length. Surface properties were investigated by mean of water absorption analysis and static contact-angle measurements using water, diiodomethane, formamide and ethylene glycol. Blood compatibility of the PUs was evaluated by in vitro adhesion assays using 111In-radiolabeled platelet-rich plasma and [125I]fibrinogen. Morphology of the adhered platelets was examined by scanning electron microscopy (SEM). Results were compared to two biomedical-grade PUs, namely Pellethane and Tecoflex. Insertion of carboxylic groups increased surface hydrophilicity and limited water uptake ( < 8% for an ion content of 5% by weight). Surface energy of all synthesized PUs was between 40 and 45 mJ/m2. Platelet adhesion and fibrinogen adsorption on the PU anionomer surfaces were affected as a function to the increase of graft length; thiopropionic was the most haemocompatible, followed by thiosuccinic and then thioglycolic acid. SEM analyses of all ionic PU samples exhibited low platelet adhesion to surfaces with no morphological modification. In conclusion, increased hydrophily, dynamic mobility and charge repulsion are synergistic key factors for enhanced haemocompatibility.

Hemocompatibilty of new ionic polyurethanes: influence of carboxylic group insertion modes.

New segmented polyurethane (PU) anionomers based on hydroxytelechelic polybutadiene (HTPB) were synthesized via two environment-friendly chemical routes. The effects of carboxylic content and ion incorporation mode on the surface properties were investigated by mean of water absorption analysis and static contact angle measurements using water, diiodomethane, formamide and ethylene glycol. Blood compatibility of the PUs was evaluated by in vitro adhesion assay using 111In-radiolabeled platelet rich plasma and 125I-fibrinogen. The morphology of platelet adhesion was also observed by scanning electron microscopy (SEM). Results were compared with a biomedical-grade PU, Pellethane. Insertion of the carboxylic groups on the soft segments (S-alpha series), using thioglycolic acid (TGA), increases surface hydrophilicity, limits water uptake (5%, for an ion content of 3.6 wt%), and reduces platelet adhesion and fibrinogen adsorption on the PUs' surfaces. In contrast, the classical insertion onto the hard segment (H-alpha series), using dimethylolpropionate (DMPA) as chain extender, leads to high water uptake (18%, for an ion content of 3.6 wt%) and promotes platelet and fibrinogen adhesion. SEM analyses of the non-ionic PUs exhibited surfaces with adhered platelets which underwent morphological modification. Similarly, the H-alpha ionic PUs show adherent and activated platelets. On the contrary, no platelet morphology changes were observed on the S-alpha ionic surfaces. In conclusion, insertion of carboxyl groups on the soft segments of PUs reduces their thrombogenicity.

Progesterone freeze-dried systems in sublingual dosage form.

Various polymer matrices were tested to enhance progesterone bioavailability as part of an emergency therapy. Among the different polymers used, i.e. poly(N-vinylpyrrolidone) (PVP), poly(ethylene oxide) (PEO), Dextran T70 and partially saponified poly(methyl glyoxylate) (PMGz), the latter gives the fastest solubilization rate. The best results were obtained with the lyophilized dosage form instead of a simple mixture of the drug within the polymer matrix. A nearly instantaneous solubilization was observed with PMGz copolymers bearing 10-40% of carboxylic groups and containing up to 20% of the drug. The instantaneous solubilization of the PMGz matrix is due to the hydrophilic moieties, and the presence of hydrophobic zones in PMGz promotes good affinity with the drug and optimal dispersion into the matrix.

Mucoadhesion of copolymers and mixtures containing polyacrylic acid.

Water-soluble polymers were synthesized from dextran and polyacrylic acid and their ocular mucoadhesion was evaluated. One series had polyacrylic acid grafted onto the polysaccharide backbone of dextran, and another series had dextran grafted onto the polyacrylic acid backbone. Mucoadhesion of these copolymers was investigated using a tensile apparatus and compared with that of polyacrylic acid/dextran mixtures prepared in different proportions. Whatever the copolymer structure, no synergistic effects were seen and mucoadhesion was not markedly increased compared to dextran. The adhesion of copolymers was the same as that of mixtures having a similar polyacrylic acid content and was always less than that of polyacrylic acid alone. Formation of an interpolymer complex occurred at concentrations up to 60% polyacrylic acid, and only above this value did bioadhesion increase above that of dextran. When this complex was dissociated by neutralization of the carboxyl groups of polyacrylic acid, the mucoadhesion of the copolymers and the mixtures was improved. These experiments demonstrated that copolymers and mixtures of dextran and polyacrylic acid did not produce polymers with improved ocular mucoadhesion.