Influence of the Radiofrequency Electromagnetic Field 40.68MHz on Adhesion of Saccharomyces cerevisiae Cells Deficient in Polyphosphatase PPN1 to Dental Alloys

Abstract

Adhesion is one of the most important properties of living organisms that help them to survive in a complex environment, but at the same time cause a variety of medical, industrial and economic problems. A lot of factors may affect adhesion and a variety of chemicals are used to decrease or prevent it, however, the influence of electromagnetic fields may significantly impact the efficiency of such compounds that is rarely considered in researches. The biosynthesis of specific adhesins requires energy stored in cells in the form of high-energy compounds, among which a special place belongs to polyphosphates (poly(P)). Poly(P) are structural units of the cell walls and influence surface charge as well. The deficiency in polyphosphatases, enzymes of the poly(P) metabolism, was shown to affect the adhesive properties of cells. Therefore, the aim of this work was to study the ability of the radiofrequency electromagnetic field to affect the adhesion of yeast cells to dental alloys and to evaluate the role of PPN1 polyphosphatase in the perception of electromagnetic signals and cell adhesion. Methods. Saccharomyces cerevisiae yeast cells of the wild type strains Y-517 and CRY, and the PPN1-deficient cells (strain CNX) were used in the study. The Ni-Cr (Wiron 99, Wirocer plus, Gialloy CB/N) and Co-Cr (Wirobond 280, Wironit, Gialloy PA) dental alloys prepared with three different casting methods were used. Yeast cells were treated with radi ofrequency electromagnetic fields (RF-EMF) (40.68 MHz, 30 W, 60 min, at thermostatic conditions) before their interaction with the alloys. Adhesion indexes were determined after direct contact of yeast cells with the surfaces of the alloys for 60 min at room temperature. Results. Chromium in the composition of the alloys had a negative effect on the adhesion, while niobium, carbon, and silicon, in contrast, stimulated it. Alloys prepared by the method of vacuum casting had the highest adhesion, while alloys prepared by centrifugal casting with melting by high-frequency current showed the greatest resistance to microbial adhesion. The efficiency of these factors significantly reduced in the case of pretreatment of yeast cells with RF-EMF and in case of deficiency of cells in PPN1: in both cases, yeast adhesion to all types of alloys was increased. The mechanisms that underlie such effects, may be different, and considering that cell surface charge and the hydrophobic properties were not changed, the effect of EMF may be a result of induction of "adaptive response" process within the yeast cells that increasing the resistance of the cell to the action of individual elements in the alloys, while, in the second case, it may be a consequence of changes in the extracellular polysaccharides composition, which take place it the PPN1-deficient cells. Conclusion. Thus, the efficiency of physical and chemical properties of dental alloys, which are aimed at the reduction of microbial adhesion, may be significantly reduced after RF-EMFs influence on the cells and in the case of polyphosphatase PPN...