Impaired insulin signaling pathway in ovarian follicles of cows with cystic ovarian disease.

Cystic ovarian disease (COD) is an important cause of infertility in dairy cattle. Follicular cell steroidogenesis and proliferation in ovulatory follicles is stimulated by hormones such as insulin and its necessary post-receptor response. The aim of this study was to determine the expression of insulin receptor (IR), IR substrate-1 (IRS1) and phosphatidylinositol 3-kinase (PI3K), key intermediates in the insulin pathway, in control cows and cows with spontaneous COD and ACTH-induced COD. IR and IRS1 mRNA levels were greater in granulosa cells and lower in follicular cysts than in control tertiary follicles. PI3K mRNA levels were similar in all follicles evaluated, whereas the expression of IR, IRS1 and PI3K was similar in theca cells. Protein expression of IR was higher in control tertiary follicles than in the same structures in animals with COD and with cysts. IRS1 and PI3K protein expression showed the same pattern in tertiary and cystic follicles. However, the protein expression of subunit alpha p85 of PI3K was greater in theca cells from tertiary follicles than in cystic follicles. These results provide new insights into the insulin response in cows with COD. The lower gene and protein expressions of some insulin downstream effectors at an early stage of the signaling pathway could negatively influence the functionality of ovaries and contribute to follicle persistence.

Spontaneous adsorption of silver nanoparticles on Ti/TiO2 surfaces. Antibacterial effect on Pseudomonas aeruginosa.

Titanium is a corrosion-resistant and biocompatible material widely used in medical and dental implants. Titanium surfaces, however, are prone to bacterial colonization that could lead to infection, inflammation, and finally to implant failure. Silver nanoparticles (AgNPs) have demonstrated an excellent performance as biocides, and thus their integration to titanium surfaces is an attractive strategy to decrease the risk of implant failure. In this work a simple and efficient method is described to modify Ti/TiO(2) surfaces with citrate-capped AgNPs. These nanoparticles spontaneously adsorb on Ti/TiO(2), forming nanometer-sized aggregates consisting of individual AgNPs that homogeneously cover the surface. The modified AgNP-Ti/TiO(2) surface exhibits a good resistance to colonization by Pseudomonas aeruginosa, a model system for biofilm formation.

Restricted surface mobility of thiolate-covered metal surfaces: a simple strategy to produce high-area functionalized surfaces.

We have studied the self-assembly of thiol monolayers on high-area nanostructured gold surfaces. These surfaces are highly irregular with a fractal dimension close to 2.5. Auger electron spectroscopy and voltammetric data indicate that thiol self-assembly with a maximum surface coverage approximately 1/3 takes place, the same result as that found for smooth gold surfaces. Therefore, neither curvature effects, which would promote higher coverage, nor excluded volume effects, which would result in lower coverage, are present in these irregular surfaces. The high surface area of the bare electrodes exhibits a rapid surface decay in different liquid media that is hindered by alkanethiolate chemisorption. The presence of thiolate SAMs reduces markedly the mass transport surface diffusion of gold adatoms, hindering surface area decay and freezing the system in a metastable state for days. This effect cannot be explained by considering only hydrocarbon-hydrocarbon chain interactions, because it is also observed for ordered arrays of adsorbed S atoms. Therefore, interactions between ordered chemisorbed species at high coverage seem to be responsible for the observed behavior. The thiol-covered high-area metallic substrates can be used to efficiently anchor a large number of molecules, biomolecules, or nanostructures, improving the performance of SAM-based optical and electrochemical devices.