Migration of fibroblasts into heart valve leaflet tissue in vitro

Heart valve allografts are widely used for surgical treatment of the heart. In recent years a new field of research has emerged dealing with allograft modification by cells of recipient by means of tissue engineering. This method involves culturing fibroblasts and endothelial cells, using recipient tissue, followed by introduction of the fibroblasts into tissues of allograft and coating its surface by the endothelial cells. This modification is expected to ensure the structural maintenance of implanted tissues and to reduce its thrombogenecity. This procedure may promote the allograft adhering to the recipient tissues, thus prolonging the terms of the valve normal functioning after implantations. For this purpose, methods of luminescent microscopy are suggested using double staining of tissue with fluorescent dyes Hoechst 33,342 and ethidium bromide, or with fluorescein diacetate and ethidium bromide. Experimental results are presented indicative of fibroblast migration from the surface to the human heart valve leaflets.     

Relationship between Degree of Dominance and Species Richness in Grass Communities with Different Productivities

The aim of this study is to test the assumption that the relationship between the degree of dominance and local species richness may be different in grass communities with different productivities. Alpine, subalpine, and low-mountain grasslands, as well as subalpine mires, alpine communities of low-snow habitats and those with long-term snow cover, steppe communities, and the grass layer of low-mountain forest communities of the Western Caucasus and Ciscaucasia, are used as objects of research. The data on the phytomass of 419 plots with an area of 0.25 m² are studied. The results show that, the higher the mean productivity of communities is, the closer the relationship between the degree of dominance and species richness is, and the closest relationship is observed in meadow communities. Possible causes of these relationships are considered. It is reasonably suggested that this may be due to the features of the organization of plant communities with high and low productivity (in particular, high or low intensity of interspecific competition).     

Intracellular pH and the proliferation of BHK-21 cells

Data are presented on the dynamics of intracellular pH (pHi) in the course of growth of BHK-21 cells in suspension and on solid substrate. Cell proliferation in suspension in the presence of bicarbonate occurs at a mean value of pHi 6.76 +/- 0.02, which is only by 0.06 higher than that for resting cells. Adhesion of cells to the substrate cause a short (12 to 24 h) increase in pHi to 7.0-7.2, then proliferation of spread cells continued at pHi 6.8 +/- 0.03. Thus, for proliferation of substrate-independent BHK-21 cells to occur, there is no need for an additional alkalization of the cytoplasm at the expense of cell adhesion to a solid substrate, so the cells grow at low pHi values and at weak alkalization provided by adding serum. Data are presented that the Cl- and HCO(3-)-transport into the cell as well as Na+/H+ exchange are involved in pHi regulation. The decrease in pHi and inhibition of cell proliferation were observed in the presence of amiloride in bicarbonate-containing medium.     

The relationship of the saturation density of multilayer cell cultures to their mass exchange with the medium

Chinese hamster fibroblasts (CHF) and NIH 3T3 cells were cultured on a glass substrate at different distances from the porous membrane separating the cells from the perfusing medium. It is shown that with perfusion of medium above the membrane there is no movement of the medium near the cells. In both the types of culture, the cells grow in multilayers, however the multilayer character of growth in CHF is more pronounced than in NIH 3T3 cells. The saturation density of the cultures depends on the cell-membrane separation, and at separations of no more than 0.2 mm exceeds the saturation density in the monolayer by 8-10 fold. The dependences of the saturation density on separation are different for CHE and NIH 3T3 cells, indicating qualitative differences in the inhibition of cell growth in monolayers between these cultures. The results obtained indicate that the inhibition of cell growth in monolayer is due to mass exchange limitations, rather than to intercellular contact interactions.     

Cytotoxic effect of dihydroquercetin and its derivatives in liposomal form and in the form of fat nanoscale emulsions

We studied cytotoxic effects of dihydroquercetin (DHQ) and its derivatives, penta-O-acetylsalicylate dihydroquercetin (PAS DHQ), penta-O-acetate dihydroquercetin (PA DHQ), and penta-O-benzoate dihydroquercetin (PB DHQ), in aqueous solutions, liposomal form, and in the form of fat emulsions, on cultured tumor cells HL-60 and HEp-2. Solubility of the DHQ derivatives in aqueous solutions was much lower than that of DHQ. Modification of DHQ either did not alter its toxicity (PAS DHQ) or significantly reduced the cytotoxic effect of DHQ on tumor cells (PA DHQ, PB DHQ). DHQ and its derivative PAS DHQ were more toxic when dissolved in an aqueous solution than in the form of liposomes. Cytotoxic effect of DHQ applied in the form of fat emulsion was significantly higher than in the liposomal form and was close to the activity of DHQ in a solution. These results can be implicated for the development of new anticancer drugs based on liposomal and fat emulsions.     

Clinical study of the efficacy of staphylococcal anatoxin in relation to the phage group to which the staphylococcal strains--the causative agents of infection--belong]

In comparing the bacteriophage group reference of the strains of pathogenic staphylococci isolated in case of postoperative complications from children given staphylococcus toxoid for prophylactic purpose and from control group it was found that prophylactic vaccinations of staphylococcus toxoid created the most intense immunity against staphylococci of the I bacteriophage group. There was found no significant association between the efficacy of the therapy and bacteriophage reference of staphylococci--the causative agents of the infection.     

The role of recipient cells in the mechanism of pathological calcification of heart valve transplants

It was found using the model of subcutaneous implantation in rats that the calcification of the aorta wall occurs by two mechanisms of which one is dependent on, and the other independent of the migration of recipient cells to the transplant.