Prevention of biofilm formation by quorum quenching.

Quorum sensing (QS) is a mechanism that enables microbial communication. It is based on the constant secretion of signaling molecules to the environment. The main role of QS is the regulation of vital processes in the cell such as virulence factor production or biofilm formation. Due to still growing bacterial resistance to antibiotics that have been overused, it is necessary to search for alternative antimicrobial therapies. One of them is quorum quenching (QQ) that disrupts microbial communication. QQ-driving molecules can decrease or even completely inhibit the production of virulence factors (including biofilm formation). There are few QQ strategies that comprise the use of the structural analogues of QS receptor autoinductors (AI). They may be found in nature or be designed and synthesized via chemical engineering. Many of the characterized QQ molecules are enzymes with the ability to degrade signaling molecules. They can also impede cellular signaling cascades. There are different techniques used for testing QS/QQ, including chromatography-mass spectroscopy, bioluminescence, chemiluminescence, fluorescence, electrochemistry, and colorimetry. They all enable qualitative and quantitative measurements of QS/QQ molecules. This article gathers the information about the mechanisms of QS and QQ, and their effect on microbial biofilm formation. Basic methods used to study QS/QQ, as well as the medical and biotechnological applications of QQ, are also described. Basis research methods are also described as well as medical and biotechnological application.

Biological activity of glycine and alanine derivatives of quaternary ammonium salts (QASs) against micro-organisms.

Quaternary ammonium salts (QASs) are commonly used in medicine, agriculture and industry and their wide usage caused the development of microbial resistance, thus there is still a need for new effective antimicrobial agents. Present work describes the biological activity of alanine- (DMALM-n) and glycine-derived (DMGM-n) QASs against planktonic and biofilm forms of micro-organisms. The antimicrobial activity was dependent mainly on the hydrocarbon chain length and surfactants with 12-16 atoms of carbon in the alkyl chain were the most active ones. The lowest MIC value was determined for DMALM-14 against Rhodotorula rubra and Saccharomyces cerevisiae (2·5 µmol l- 1 ). Generally, alanine derivatives showed stronger effects against micro-organisms than glycine-derived QASs. Alanine-derived surfactants with 12-16 carbons in the alkyl chain had antiadhesive properties on the polystyrene surface, preventing cell attachment (about 70% of inhibition for C. albicans and 40% for S. epidermidis). Strong adhesion reduction was also observed on the stainless steel surface and the highest reduction was observed for C. albicans cells incubated on surface pretreated with DMGM-16. Moreover, DMGM-16 and DMALM-16 prevented C. albicans filamentation, one of the determinants of cell adhesion. Surfactants with C16 alkyl chain (DMGM-16 and DMALM-16) eradicated bacterial and yeast biofilm (from 60 to 90% of reduction observed after incubation of the previously grown biofilm in the presence of the highest tested concentration of the surfactant - 400 µmol l- 1 ) and reduced its viability. Strong antimicrobial activity as well as antiadhesive properties make alanine- and glycine-derived QASs the potential candidates for future application as disinfectants. SIGNIFICANCE AND IMPACT OF THE STUDY: Cationic surfactants are used in many fields, among others in medicine, cosmetic and pharmaceutical industry. Their usage on a large scale caused the development of microbial resistance mechanisms to such compounds. Thus, there is a need to synthesize new surfactants with potential application as effective disinfectants to combat both planktonic and biofilm forms of micro-organisms. Present work focuses on the antimicrobial activity of chosen quaternary ammonium salts.

A new approach to spectroscopic and structural studies of the nano-sized silicate-substituted hydroxyapatite doped with Eu3+ ions.

Nanocrystalline silicate-substituted hydroxyapatites Ca10-xEux(PO4)4(SiO4)2(OH)2 (where x = 0.5, 1.0, 2.0, 5.0 mol%) doped with Eu3+ ions were synthesized using a microwave assisted hydrothermal method and heat-treated in the temperature range from 700 to 1000 °C. The concentration of optically active Eu3+ ions was established in the range of 0.5-5 mol% to investigate the preference of occupancy sites. The structural and morphological properties of the obtained biomaterials were determined by using XRD (X-Ray Powder Diffraction), TEM (Transmission Electron Microscopy) and SEM (Scanning Electron Microscopy) techniques as well as infrared (IR) spectroscopy. The average particle sizes were calculated to be in the range from 20 nm to 80 nm by the Rietveld method. The charge compensation mechanism in europium(iii)-doped silicate-substituted hydroxyapatite was proposed in the Kröger-Vink-notation. The luminescence properties (the emission, excitation spectra and emission kinetics) of the Eu3+ ion-doped apatite were recorded depending on the dopant concentration. The existence of Eu2+ ions was confirmed by the emission spectra.

[Preliminary assessment of the role of IL-5 in the pathogenesis of nasal polyps]. / Próba oceny roli IL-5 w patogenezie polipów nosa--doniesienie wstepne.

Preliminary results of IL-5 levels in homogenates derived from nasal polyps tissue are presented. The IL-5 concentration was assessed by immunoenzymatic method (ELISA, R&D, Systems Minneapolis). 26 patients at age 21-60 years were examined. IL-5 cevels were higher in polips with allergic and were examined. IL-5 levels were higher in polips with allergic and aspirin idiocracy background compared with inflammatory polips. In addition, IL-5 levels were increased in recurrent polips.

[TNF alpha in serum of patients with cholesteatoma]. / TNF alfa w surowicy chorych z przewleklym zapaleniem ucha srodkowego z perlakiem.

TNF alfa levels in the sera of patients with cholesteatoma were investigated. Immunoradiometric method was used. TNF alfa levels in the sera of patients with cholesteatoma were higher than in the sera of a control group. The differences were statistically significant.