Enhanced bioadhesivity of dopamine-functionalized polysaccharidic membranes for general surgery applications

An emerging strategy to improve adhesiveness of biomaterials in wet conditions takes inspiration from the adhesive features of marine mussel, which reside in the chemical reactivity of catechols. In this work, a catechol-bearing molecule (dopamine) was chemically grafted onto alginate to develop a polysaccharide-based membrane with improved adhesive properties. The dopamine-modified alginates were characterized by NMR, UV spectroscopy and in vitro biocompatibility. Mechanical tests and in vitro adhesion studies pointed out the effects of the grafted dopamine within the membranes. The release of HA from these resorbable membranes was shown to stimulate fibroblasts activities (in vitro). Finally, a preliminary in vivo test was performed to evaluate the adhesiveness of the membrane on porcine intestine (serosa). Overall, this functionalized membrane was shown to be biocompatible and to possess considerable adhesive properties owing to the presence of dopamine residues grafted on the alginate backbone

Is increased time to diagnosis and treatment in symptomatic cancer associated with poorer outcomes?:Systematic review

background: It is unclear whether more timely cancer diagnosis brings favourable outcomes, with much of the previous evidence, in some cancers, being equivocal. We set out to determine whether there is an association between time to diagnosis, treatment and clinical outcomes, across all cancers for symptomatic presentations. methods: Systematic review of the literature and narrative synthesis. results: We included 177 articles reporting 209 studies. These studies varied in study design, the time intervals assessed and the outcomes reported. Study quality was variable, with a small number of higher-quality studies. Heterogeneity precluded definitive findings. The cancers with more reports of an association between shorter times to diagnosis and more favourable outcomes were breast, colorectal, head and neck, testicular and melanoma. conclusions: This is the first review encompassing many cancer types, and we have demonstrated those cancers in which more evidence of an association between shorter times to diagnosis and more favourable outcomes exists, and where it is lacking. We believe that it is reasonable to assume that efforts to expedite the diagnosis of symptomatic cancer are likely to have benefits for patients in terms of improved survival, earlier-stage diagnosis and improved quality of life, although these benefits vary between cancers

Les fluides électrorhéologiques : rôle de la conductivité des différents constituants

Après un rappel sur l'influence du champ électrique sur les propriétés rhéologiques de suspensions de fines particules dans un liquide isolant, des arguments généraux sont présentés qui montrent qu'en tension continue, ce sont les propriétés de conduction des deux constituants qui déterminent l'interaction entre les particules. L'effet électrorhéologique ne peut avoir lieu que pour des particules solides plus conductrices que le liquide (dans le cas contraire un effet “négatif” est observé). Un modèle permettant d'estimer la force d'interaction entre particules d'un fluide électrorhéologique est ensuite proposé. Ce modèle est qualitativement vérifié aussi bien sur une expérience à grande échelle (sphères de rayon 0,7 cm) que sur un fluide réel. Le cas des champs alternatifs est brièvement abordé.The influence of an electric field on the rheological properties of suspensions of small particles in an insulating liquid is first recalled. Then general arguments are given which show that, under DC fields, the particle/particle interaction is controlled by the conduction properties of both constituents. The electrorheological effect occurs only for solid that present a higher conductivity than the liquid (in the reserve case, a “negative” effect is obtained). Then a model is proposed which gives estimates of the attraction force between particles of an ER fluid. This model is qualitatively confirmed by results on a large scale experiment (spheres of radius $R=0.7$ cm) as well as on a real fluid. The case of AC fields is also examined

Polysaccharide-Coated Thermosets for Orthopedic Applications: From Material Characterization to In Vivo Tests

The long-term stability and success of orthopedic implants depend on the osseointegration process, which is strongly influenced by the biomaterial surface. A promising approach to enhance implant integration involves the modification of the surface of the implant by means of polymers that mimic the natural components of the extracellular matrix, for example, polysaccharides. In this study, methacrylate thermosets (bisphenol A glycidylmethacrylate/triethyleneglycol dimethacrylate), a widely used composition for orthopedic and dental applications, have been coated by electrostatic deposition of a bioactive chitosan-derivative. This polysaccharide was shown to induce osteoblasts aggregation in vitro, to stimulate cell proliferation and to enhance alkaline phosphatase activity. The coating deposition was studied by analyzing the effect of pH and ionic strength on the grafting of the polysaccharide. Contact angle studies show that the functionalized material displays a higher hydrophilic character owing to the increase of surface polar groups. The mechanical properties of the coating were evaluated by nanoindentation studies which point to higher values of indentation hardness and modulus (E) of the polysaccharide surface layer, while the influence of cyclic stress on the construct was assessed by fatigue tests. Finally, in vivo tests in minipigs showed that the polysaccharide-based implant showed a good biocompatibility and an ability for osseointegration at least similar to that of the titanium Ti6Al4V alloy with roughened surface

Terminal sterilization of BisGMA-TEGDMA thermoset materials and their bioactive surfaces by supercritical CO2

The development of biomaterials endowed with bioactive features relies on a simultaneous insight into a proper terminal sterilization process. FDA recommendations on sterility of biomaterials are very strict: a sterility assurance level (SAL) of 10\u20136 must be guaranteed for biomaterials to be used in human implants. In the present work, we have explored the potential of supercritical CO2 (scCO2) in the presence of H2O2 as a low-temperature sterilization process for thermoset materials and their bioactive surfaces. Different conditions allowing for terminal sterilization have been screened and a treatment time\u2013amount of H2O2 relationship proposed. The selected terminal sterilization conditions did not notably modify the mechanical properties of the thermoset nor of their fiber-reinforced composites. This was confirmed by \u3bcCT analyses performed prior to and after the treatment. On the contrary, terminal sterilization in the presence of H2O2 induced a slight decrease in the surface hardness. The treatment of the thermoset material with scCO2 led to a reduction in the residual unreacted monomers content, as determined by means of high performance liquid chromatography (HPLC) analyses. Finally, it was found that a thermoset coated with a polysaccharide layer containing silver nanoparticles maintained a very high antimicrobial efficacy even after the scCO2-based terminal sterilization

Effects of supercritical carbon dioxide sterilization on polysaccharidic membranes for surgical applications

Sterilization methods such as &3-irradiation, steam sterilization and ethylene oxide gas treatment can have negative effects on molecular structure and properties of polysaccharide-based biomaterials. In this perspective, the use of supercritical carbon dioxide (scCO2) has been proposed as an alternative method for biomaterial sterilization. In this work, chemical, mechanical and biological properties of polysaccharidic membranes for surgical applications were investigated after sterilization by scCO2. Four sets of sterilizing conditions were considered and SEC analyses were performed in order to identify the one with lower impact on the polysaccharidic matrix of membranes (alginate). Mechanical tests showed that the resistance of membranes was slightly affected after sterilization. Biological analyses proved the biocompatibility of the sterilized membranes both in vitro and in a preliminary in vivo test. Overall, this study points out that this sterilization technique can be successfully employed to achieve an effective and safe sterilization of polysaccharidic membranes for surgical us