Mineralized alginate hydrogels using marine carbonates for bone tissue engineering applications

The search for an ideal bone tissue replacement has led to the development of new composite materials designed to simulate the complex inorganic/organic structure of bone. The present work is focused on the development of mineralized calcium alginate hydrogels by the addition of marine derived calcium carbonate biomineral particles. Following a novel approach, we were able to obtain calcium carbonate particles of high purity and complex micro and nanostructure dependent on the source material. Three different types of alginates were selected to develop inorganic/organic scaffolds in order to correlate alginate composition with scaffold properties and cell behavior. The incorporation of calcium carbonates into alginate networks was able to promote extracellular matrix mineralization and osteoblastic differentiation of mesenchymal stem cells when added at 7 mg/ml. We demonstrated that the selection of the alginate type and calcium carbonate origin is crucial to obtain adequate systems for bone tissue engineering as they modulate the mechanical properties and cell differentiation.

Inhibition of ciliary activity in organ cultures of ferret trachea in reference to genetic and biological characters in influenza virus strains

As reported previously, attenuated stable inhibitor-resistant influenza viruses can be screened by a 50% ciliary activity inhibition test in ferret tracheal organ cultures. This test was further applied to a 5 attenuated cold-adapted influenza strains and to 11 strains with known a percentage of RNA-RNA hybridization with the parental A/PR/8/34 (HON1) virus strain. Again, with one exception, attenuated strains could be clearly differentiated from virulent ones. It was concluded that virulence of influenza strains for man can be detected using this test regardless of the techniques used to prepare attenuated variants. A preliminary screening of attenuated candidates for live influenza vaccines can be achieved with confidence on ferret tracheal organ cultures.

In vitro markers for measuring residual virulence for men of live attenuated influenza viruses

Human and equine influenza strains attenuated by consecutive passages in the presence of normal horse serum (NHS) on allantois-on-shell system (AOS) and administered to human volunteers or horses as possible live virus vaccine candidates were tested in organ cultures of ferret and hamster trachea. Temperature sensitivity, virus replication, interferon induction and neuraminidase activity were also investigated. Observation of the ciliary activity of each ring was made daily. Influenza strains which were incompletely attenuated following two to five passages on AOS + NHS system and caused severe to mild symptoms of influenza in volunteers or horses also caused a 50% inhibition of the activity of the ciliated epithelium earlier than did completely attenuated strains following ten passages on the same system. The A/Hong Kong/68 strain attenuated by Beare and Bynoe was used as a reference strain in every test. This technique appears to be valuable for screening live influenza vaccine candidates and may prevent risking severe illness in volunteers. No significant results could be ascertained with other markers investigated.