Synthesis, characterization, in vitro biocompatibility and antibacterial properties study of nanocomposite materials based on hydroxyapatite-biphasic ZnO micro- and nanoparticles embedded in Alginate matrix.

The paper presents the results of studies of biocompatibility and antibacterial properties of multiphase nanocomposite materials based on HA-Alg-ZnO (hydroxyapatite­sodium alginate-biphasic zinc oxide) and HA-ZnO (hydroxyapatite­zinc oxide), which were synthesized from the analytically pure calcium nitrate tetrahydrate, ammonium hydrophosphate, hydrous ammonia, zinc nitrate hexahydrate and calcium chloride. The samples' antimicrobial activity assessment was carried out on Gram-negative (E. coli, P. aeruginosa) and Gram-positive bacteria (S. aureus and S. epidermidis) test cultures by the co-incubation and modified "agar diffusion" methods. The murine fibroblast cells were used for the biocompatibility tests and cytotoxicity evaluation. It was shown that synthesized nanocomposite material has a multiphase nanoscale architecture, where ZnO nanocrystals are represented by two lattices: cubic and hexagonal. The possible explanation of ZnO nanocrystals' phase transition is given. At the same time, a partial replacement of Ca2+ ions by Zn2+ ions in the HA lattice possibly occurs due to processing of composite by US radiation. The replacement was evidenced by the non-stoichiometric Ca/P ratio < 2.16, OPO lines' shifting on FTIR spectrum and TEM analysis. The studied composite demonstrate a pronounced antibacterial activity due to the incorporation of ZnO particles into sodium alginate and moistened powder of hydroxyapatite. Both forms of HA-ZnO (suspension) and HA-Alg-ZnO (beads) are biocompatible. An interpretation of the process of Zn ions' embedding into hydroxyapatite and alginate matrix is given, as well as their influence on the biomimetic composite properties is discussed in details. STATEMENT OF SIGNIFICANCE: A number of studies have shown that Zn effectively inhibits the growth and development of bacteria and yeast fungi. Zinc plays an important role in the creation of new antimicrobial agents, and zinc-doped hydroxyapatite will find further application in biomedicine. In this regard, the phase states of zinc oxide, as well as the processes of calcium replacement by zinc in calcium apatite and in alginate should be explored fully. Nowadays we have lack of information and the study's results about those interactions. The present study provides data of the multiphase morphology, antimicrobial activity, biocompatibility and cytotoxicity of the biomimetic nanostructured composite materials, such as sodium alginate/hydroxyapatite/ZnO based granules and hydroxyapatite/ZnO based hydrogel, and the establishing Zn ions' behavior patterns with another composite components.

Gal4-gene-dependent alterations of embryo development and cell growth in primary culture of sea urchins.

Primary cell cultures from sea urchins have a low proliferative level that prevents the establishment of long-term cultures. To increase expression levels of the genes regulating cell growth in sea urchins, and thus enhance cell growth, we used the transcriptional activator gene Gal4 found earlier in yeast. Sea urchin embryos were treated with plasmid DNA containing the Gal4 gene. Expression of the transgene was confirmed by reverse transcriptase polymerase chain reaction. When the fully functional gene was used, embryos effectively formed teratoma-like structures after 50 to 55 hours of cultivation. In contrast, the Gal4 gene, devoid of acidic activating regions, possessed little activity as a teratogen. The Gal4-treated cells in blastula-derived culture showed higher DNA synthesis and higher proliferative activity than control cells. We suggest that formation of the teratoma-like structures in embryos, activation of DNA synthesis, and significant increase of cell number in embryo-derived cell cultures could be attributed to Gal4 gene action.

[Chronoreactiometric system with biotechnical feedback]. / Khronoreaktsiometricheskaia sistema s biotekhnicheskoi obratnoi sviaz'iu.

The paper deals with a principle in the construction and apparatus realization of a biotechnical feedback system (BT-FS) for self-regulation (correction) of rapid motor reactions (RMR). Experiments have indicated that the system has good training and rehabilitative abilities as the examinee develops permanent RMR.

Isolation and partial characterization of myogenic cells from mussel larvae in vitro.

The main finding of the present study is the discovery of the possibility of a morphofunctional myogenic differentiation of larval mussel cells in vitro. The shape and extensive cytoskeletal network of the cultured contracting cells mimic largely those of smooth muscle cells in vivo. However, the behavior and protein composition of these cells are not completely identical with those of smooth muscle cells. Contracting mussel cells in vitro, as well as differentiated smooth muscles, demonstrate both phasic and tonic contractions. The paramyosin to myosin ratio in the cultured mussel cells is far less than that in the muscles of veliger larvae and adult mussels. We have found the protein carpets with various adhesive characteristics determine different development pathways. Myogenic differentiation is only observed in spreading cells. Non-spreading adherent cells plated on collagen carpet show high synthetic activity but the commitment of contractile phenotype is inhibited. Our results confirm that the myogenic program established in early embryogenesis of molluscs can be realized during the cultivation of cells from premyogenic larval stages.