3D-FEA of osseointegration percentages and patterns on implant-bone interfacial stresses

The aim of this study was to investigate the expression and distribution patterns of the inducible isoform of nitric oxide synthase (iNOS) in rat placenta during gestation and term labour. The expression of iNOS isoform was assessed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting with monoclonal antibodies. Two specific bands were detected corresponding to 135 and 124 kDa in all placenta samples. The upper band (135 kDa) was identified as iNOS due to its correspondence with the band obtained with mouse macrophages (positive control). Compared with its concentrations on day 16, iNOS decreased steadily toward the end of gestation to approximately 37% on day 20, 20% on day 22 before labour and 12% during labour (p < 0.01). The lower band (124 kDa) drastically increased (to almost double) from day 16 to day 18 but returned to initial values on day 22, during delivery. Immunohistochemical staining of placentae at day 16 and 22 using rabbit polyclonal anti-iNOS antibody revealed labelling specifically concentrated in the trophospongial cell layer, at the fetal-maternal interface. The most conspicuous iNOS staining was associated with islands of cells referred to as vacuolated 'glycogen cells'. Staining was greatly decreased during labour. The changes in placental iNOS expression suggest a 'paracrine' role for NO in regulating uterine contractility, blood flow and immunosuppression required for pregnancy maintenance. NO withdrawal at term may also be involved in the initiation of labour.     

High-resolution structure of a polyomavirus VP1-oligosaccharide complex: implications for assembly and receptor binding

The crystal structure of a recombinant polyomavirus VP1 pentamer (residues 32-320) in complex with a branched disialylated hexasaccharide receptor fragment has been determined at 1.9 A resolution. The result extends our understanding of oligosaccharide receptor recognition. It also suggests a mechanism for enhancing the fidelity of virus assembly. We have previously described the structure of the complete polyomavirus particle complexed with this receptor fragment at 3.65 A. The model presented here offers a much more refined view of the interactions that determine carbohydrate recognition and allows us to assign additional specific contacts, in particular those involving the (alpha2,6)-linked, branching sialic acid. The structure of the unliganded VP1 pentamer, determined independently, shows that the oligosaccharide fits into a preformed groove and induces no measurable structural rearrangements. A comparison with assembled VP1 in the virus capsid reveals a rearrangement of residues 32-45 at the base of the pentamer. This segment may help prevent the formation of incorrectly assembled particles by reducing the likelihood that the C-terminal arm will fold back into its pentamer of origin.