eDNA Inactivation and Biofilm Inhibition by the PolymericBiocide Polyhexamethylene Guanidine Hydrochloride (PHMG-Cl)

The choice of effective biocides used for routine hospital practice should consider the role of disinfectants in the maintenance and development of local resistome and how they might affect antibiotic resistance gene transfer within the hospital microbial population. Currently, there is little understanding of how different biocides contribute to eDNA release that may contribute to gene transfer and subsequent environmental retention. Here, we investigated how different biocides affect the release of eDNA from mature biofilms of two opportunistic model strains Pseudomonas aeruginosa ATCC 27853 (PA) and Staphylococcus aureus ATCC 25923 (SA) and contribute to the hospital resistome in the form of surface and water contaminants and dust particles. The effect of four groups of biocides, alcohols, hydrogen peroxide, quaternary ammonium compounds, and the polymeric biocide polyhexamethylene guanidine hydrochloride (PHMG-Cl), was evaluated using PA and SA biofilms. Most biocides, except for PHMG-Cl and 70% ethanol, caused substantial eDNA release, and PHMG-Cl was found to block biofilm development when used at concentrations of 0.5% and 0.1%. This might be associated with the formation of DNA–PHMG-Cl complexes as PHMG-Cl is predicted to bind to AT base pairs by molecular docking assays. PHMG-Cl was found to bind high-molecular DNA and plasmid DNA and continued to inactivate DNA on surfaces even after 4 weeks. PHMG-Cl also effectively inactivated biofilm-associated antibiotic resistance gene eDNA released by a pan-drug-resistant Klebsiella strain, which demonstrates the potential of a polymeric biocide as a new surface-active agent to combat the spread of antibiotic resistance in hospital settings.     

An outer shell of positively charged poly(ethyleneimine) strongly increases the transfection efficiency of calcium phosphate/DNA nanoparticles

Nanoparticles with an inner core of calcium phosphate, followed by layers of DNA and calcium phosphate and an outer layer of poly(ethyleneimine) (PEI) were prepared, characterized, and tested on different cell lines (HeLa, T24, and NIH3T3). A considerable increase in transfection efficiency was found for such nanoparticles, compared to the commercial reagent Polyfect^® (a cationic dendrimer). The DNA is incorporated into the nanoparticles and protected from the attack by enzymes (nucleases) inside the cytoplasm of cells. The outer layer of PEI leads to electrosteric colloidal stabilization and gives a positive charge to the nanoparticle, which is helpful for the penetration through the negatively charged cell membrane.     

Delayed effects of chronic low-dose high linear energy transfer (LET) radiation on mice in vivo

In the present work, the delayed effects of chronic high linear energy transfer (LET) radiation in polychromatic erythrocytes (PCEs) of mice bone marrow were investigated in vivo. Irradiation of the two-month-old SHK white mongrel random-bred male mice was performed in the radiation field behind the concrete shield of the accelerator of 70 GeV protons to accumulate doses of 0.005-0.16 Gy. The dependence of the biological response on dose, adaptive response (AR) and genomic instability (GI) in F(1) and F(2) generations from males irradiated with doses of 0.005 and 0.16 Gy and from males exposed to combined action of immunomodulator-bendazol hydrochloride (BH) and of 0.16 Gy irradiation, were examined using the micronucleus formation test. The data demonstrated that irradiation of mice with these doses lead to an increase in the level of cytogenetic damage and induces no AR. With analysis of the bone marrow radiosensitivity to 1.5 Gy of X rays and the capacity to AR it was found that the chronic high-LET irradiation of parents induced the GI at least two generations. The combined exposure to BH and the dose of 0.16 Gy induces no AR in F(0) generation but induces AR in F(1) and F(2) offspring.     

Lipid peroxidation in patients with ischemic heart disease, hyperlipidemia and/or hypertension while polyunsaturated omega-3 fatty acids of plant and animal origin were in their diet

Missing anterior teeth are being replaced by implant-supported restorations quite frequently in modern dentistry. Providing the patient with a temporary prosthesis prior to or following implant fixture placement must satisfy established esthetic and functional criteria. When orthodontic treatment is included as part of the overall treatment effort, additional considerations include the retention and stabilization of newly established tooth positions. This article describes the fabrication, use and advantages of a provisional anterior prosthesis that replaces missing teeth prior to or following implant placement.     

Structure of white phases after heat treatment

Conclusions During seizing of parts under conditions of vibration white phases are formed as the result of processes similar to processes during quenching with rapid cooling; the structure is the same as that in quenched steels but differs by its higher stresses and less stable condition; the white phase is more resistant to decomposition than martensite formed after standard quenching.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 5, pp. 61–63, May, 1979.     

Nature and properties of secondary structures formed during fretting corrosion

Conclusions The secondary structures formed in the surface layers of a materlal during fretting corrosion consist of nonmetallic phases — oxides of the principal metallic element and solutions of variable concentration of oxygen or the principal metallic element based on these oxides.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 8, pp. 25–27, August, 1978.     

Morphological features of porous silicon carbide obtained via a carbothermal method

Samples of porous silicon carbide were obtained using sucrose or carbon and aerosil or silica mesoporous molecular sieves (SBA‐3, SBA‐15, KIT‐6 and MCF). Fibers content in silicon carbide samples is higher when the mesopore surface area of carbon materials derived from carbon‐silica composites is lower. Based on the found correlation between the morphology and porosity of SiC and mesopore surface area of the carbon component in the composites, a templating action of carbon in carbothermal reduction was suggested.