Bioinspired Nanofeatured Substrates: Suitable Environment for Bone Regeneration.

Bone mimicking coatings provide a complex microenvironment in which material, through its inherent properties (such as nanostructure and composition), affects the commitment of stem cells into bone lineage and the production of bone tissue regulating factors required for bone healing and regeneration. Herein, a bioactive mineral/biopolymer composite made of calcium phosphate/chitosan and hyaluronic acid (CaP-CHI-HA) was elaborated using a versatile simultaneous spray coating of interacting species. The resulting CaP-CHI-HA coating was mainly constituted of bioactive, carbonated and crystalline hydroxyapatite with 277 ± 98 nm of roughness, 1 µm of thickness, and 2.3 ± 1 GPa of stiffness. After five days of culture, CaP-CHI-HA suggested a synergistic effect of intrinsic biophysical features and biopolymers on stem cell mechanobiology and nuclear organization, leading to the expression of an early osteoblast-like phenotype and the production of bone tissue regulating factors such as osteoprotegerin and vascular endothelial growth factor. More interestingly, amalgamation with biopolymers conferred to the mineral a bacterial antiadhesive property. These significant data shed light on the potential regenerative application of CaP-CHI-HA bioinspired coating in providing a suitable environment for stem cell bone regeneration and an ideal strategy to prevent implant-associated infections.

Epidemiology of Acinetobacter spp.-associated healthcare infections and colonization among children at a tertiary-care hospital in Saudi Arabia: a 6-year retrospective cohort study.

A retrospective cohort study was conducted among hospitalized children less than 12 years of age who had Acinetobacter spp. isolated from ≥1 cultures between October 2001 and December 2007 at King Abdulaziz Medical City in Riyadh, Saudi Arabia. Children with multidrug-resistant (MDR) Acinetobacter spp. healthcare-associated infections (HAIs) were compared to children with antimicrobial-susceptible Acinetobacter spp. HAIs and to children colonized with Acinetobacter. Children with MDR Acinetobacter spp. HAIs were older (p = 0.01), more likely to be admitted to an intensive care unit (ICU) (p = 0.06), and had a higher mortality rate (p = 0.02) than colonized children. Children with MDR Acinetobacter spp. HAIs were older than children with antimicrobial-susceptible Acinetobacter spp. HAIs (p = 0.0004), but their mortality rates were similar. Among children with MDR Acinetobacter spp. HAIs, burn injuries were the most common underlying illness. HAIs caused by MDR or susceptible Acinetobacter spp. occurred after prolonged hospitalization, suggesting nosocomial acquisition. Patients infected with MDR Acinetobacter spp. frequently received inappropriate empiric therapy (73.9 %). Further studies are needed in order to identify effective strategies to prevent nosocomial transmission and effective ways of improving patient outcomes.

Mechanical properties of nanotubes of polyelectrolyte multilayers.

The elastic properties of nanotubes fabricated by layer-by-layer (LbL) assembly of polyelectrolytes in the nanopores of polycarbonate track-etched membranes have been investigated by resonant contact Atomic Force Microscopy (AFM), for nanotube diameters in the range of 100 to 200 nm. The elastic modulus of the nanotubes was computed from the resonance frequencies of a cantilever resting on freely suspended LbL nanotubes. An average value of 115 MPa was found in air for Young's modulus of these nanostructures, well below the values reported for dry, flat multilayers, but in the range of values reported for water-swollen flat multilayers. These low values are most probably due to the lower degree of ionic cross-linking of LbL nanotubes and their consequently higher water content in air, resulting from the peculiar mode of growth of nanoconfined polyelectrolyte multilayers.