The HOCl dry fog-is it safe for human cells?

This study aims to investigate if high-concentration HOCl fogging disinfection causes cytotoxicity and genotoxicity to cultured primary human skin fibroblasts. The cells were exposed to a dry fog of HOCl produced from solutions with a concentration of 300 ppm (5.72 mM) or 500 ppm (9.53 mM). After four times when fibroblasts were exposed to aerosolized HOCl at a concentration of 500 ppm for 9 minutes, significant cytotoxicity and genotoxicity effects were observed. Significant changes in the morphology of fibroblasts and cell death due to membrane disruption were observed, independent of the number of exposures. Flow cytometry analyses performed under these experimental conditions indicated a decrease in the number of cells with an intact cell membrane in the exposed samples compared to the sham samples, dropping to 49.1% of the total cells. Additionally, under the same conditions, the neutral comet assay results demonstrated significant DNA damage in the exposed cells. However, no analogous damages were found when the cells were exposed to aerosolized HOCl generated from a 300-ppm solution for 3 minutes, whether once or four times. Therefore, we have concluded that aerosolized HOCl in dry fog, with a concentration exceeding 300 ppm, can cause cytotoxic and genotoxic effects on human skin fibroblasts.

Nanosecond Pulsed Electric Field Only Transiently Affects the Cellular and Molecular Processes of Leydig Cells.

The purpose of this study was to verify whether the nanosecond pulsed electric field, not eliciting thermal effects, permanently changes the molecular processes and gene expression of Leydig TM3 cells. The cells were exposed to a moderate electric field (80 quasi-rectangular shape pulses, 60 ns pulse width, and an electric field of 14 kV/cm). The putative disturbances were recorded over 24 h. After exposure to the nanosecond pulsed electric field, a 19% increase in cell diameter, a loss of microvilli, and a 70% reduction in cell adhesion were observed. Some cells showed the nonapoptotic externalization of phosphatidylserine through the pores in the plasma membrane. The cell proportion in the subG1 phase increased by 8% at the expense of the S and G2/M phases, and the DNA was fragmented in a small proportion of the cells. The membrane mitochondrial potential and superoxide content decreased by 37% and 23%, respectively. Microarray's transcriptome analysis demonstrated a negative transient effect on the expression of genes involved in oxidative phosphorylation, DNA repair, cell proliferation, and the overexpression of plasma membrane proteins. We conclude that nanosecond pulsed electric field affected the physiology and gene expression of TM3 cells transiently, with a noticeable heterogeneity of cellular responses.

The red-light emitting diode irradiation increases proliferation of human bone marrow mesenchymal stem cells preserving their immunophenotype.

PURPOSE: For effective clinical application of human bone marrow mesenchymal stem cells (hBM-MSCs), the enhancement of their proliferation in vitro together with maintaining the expression of their crucial surface antigens and differentiation potential is necessary. The present study aimed to investigate the effect of light-emitting diode (LED) irradiation on hBM-MSCs proliferation after two, five, or nine days post-irradiation. MATERIALS AND METHODS: The hBM-MSCs were exposed to the LED light at 630 nm, 4 J/cm2, and power densities of 7, 17, or 30 mW/cm2. To assess the cell proliferation rate in the sham-irradiated and irradiated samples the cells metabolic activity and DNA content were determined. The number of apoptotic and necrotic cells in the samples was also evaluated. The expression of the crucial surface antigens of the hBM-MSCs up to nine days after irradiation at 4 J/cm2 and 17 mW/cm2 was monitored with flow cytometry. Additionally, the potential of hBM-MSCs for induced differentiation was measured. RESULTS: When the metabolic activity was assayed, the significant increase in the cell proliferation rate by 31 and 50% after the irradiation with 4 J/cm2 and 17 mW/cm2, respectively, was observed at day five and nine when compared to the sham-irradiated cells (p < .05). Similarly, DNA content within the irradiated hBM-MSCs increased by 31 and 41% at day five and nine after the irradiation with 4 J/cm2 and 17 mW/cm2 in comparison to the sham-irradiated cells. LED irradiation did not change the expression of the crucial surface antigens of the hBM-MSCs up to nine days after irradiation at 4 J/cm2 and 17 mW/cm2. At the same experimental conditions, the hBM-MSCs maintain in vitro their capability for multipotential differentiation into osteoblasts, adipocytes, and chondrocytes. CONCLUSION: Therefore, LED irradiation at a wavelength of 630 nm, energy density 4 J/cm2, and power density 17 mW/cm2 can effectively increase the number of viable hBM-MSCs in vitro.

Fast, reagentless and reliable screening of "white powders" during the bioterrorism hoaxes.

The classification of dry powder samples is an important step in managing the consequences of terrorist incidents. Fluorescence decays of these samples (vegetative bacteria, bacterial endospores, fungi, albumins and several flours) were measured with stroboscopic technique using an EasyLife LS system PTI. Three pulsed nanosecond LED sources, generating 280, 340 and 460nm were employed for samples excitation. The usefulness of a new 460nm light source for fluorescence measurements of dry microbial cells has been demonstrated. The principal component analysis (PCA) and hierarchical cluster analysis (HCA) have been used for classification of dry biological samples. It showed that the single excitation wavelength was not sufficient for differentiation of biological samples of diverse origin. However, merging fluorescence decays from two or three excitation wavelengths allowed classification of these samples. An experimental setup allowing the practical implementation of this method for the real time fluorescence decay measurement was designed. It consisted of the LED emitting nanosecond pulses at 280nm and two fast photomultiplier tubes (PMTs) for signal detection in two fluorescence bands simultaneously. The positive results of the dry powder samples measurements confirmed that the fluorescence decay-based technique could be a useful tool for fast classification of the suspected "white powders" performed by the first responders.

Biological threat detection in the air and on the surface: how to define the risk.

The improvements in the existing methods of rapid detection and biological pathogen surveillance are still needed. The new spectroscopic methods that rely on the unique structural features and intrinsic fluorescence of microorganisms are well fitted for monitoring the spread of airborne biological agents or their reagentless detection in the air, and these methods may bring a new quality to bioaerosols remote detection. This review describes the problem of the confidence in the environmental testing results that may affect clearance standard, sampling techniques, and the estimation of risk of human exposure to the low concentrations of harmful microorganisms during bioterrorist event or naturally occurring outbreaks. Higher recovery efficiency of dangerous biological agents from the air and contaminated surfaces would enable more reliable environmental human risk exposure assessment.

Use of MTT assay for determination of the biofilm formation capacity of microorganisms in metalworking fluids.

Biofilm formation is a well-known problem in management of metalworking fluid systems. Due to persistence of microorganisms within biofilms, the reappearance of various species of bacteria, including nontuberculous mycobacteria is often observed after the use of biocides and/or cleaning of delivery systems and replacement of cooling fluid. The aim of this study was to determine the usefulness of the tetrazolium salt assay (MTT assay) for assessing the viability of bacteria in biofilms formed in vitro in fresh and used cutting oils, as well as their susceptibility to antimicrobial biocides. Biofilms were established in the microtiter plate format. The results showed that quantification of formazan, a product of the tetrazolium salt reduction by electron transport system could be used for determination of the propensity of bacteria to form biofilms in these complex media. The use of the assay allows also determination of antimicrobial activity of biocides against biofilms in fresh and used metalworking fluids. Biofilms produced by Gram-negative isolates recovered from field metalworking fluids as well as the wild bacterial communities differed in metabolic activity depending on the type of fresh coolants. The MTT assay has high-throughput potential and can be efficiently used for determination of biofilm-forming capacity of microorganisms from individual machines in metalworking industry. The use of the assay may also guide the selection of the most appropriate biocide to fight these microorganisms.

Evaluation of applicability of the Sartorius Airport MD8 sampler for detection of Bacillus endospores in indoor air.

This study was designed to evaluate the measuring range and lowest limit of detection of Bacillus endospores in the ambient room air when the Sartorius MD8 sampler, and two different culture methods for bacterial enumeration were used. Different concentrations of bioaerosol were generated inside the test chamber filled with either the high-efficiency particulate air (HEPA)-filtered air or with the ambient room air. The detection of endospores in the HEPA-filtered air was achievable: (1) when they were aerosolized at a concentration above 7.56 × 10(3) CFU/m(3) and analyzed with spread plate method, and (2) when they were aerosolized at a concentration above 4.00 × 10(2) CFU/m(3) and analyzed with pour plate method. The detection of endospores in the ambient room air was possible: (1) when they were aerosolized at a concentration above 9.1 × 10(3) CFU/m(3) and analyzed with spread plate method, and (2) when they were aerosolized at a concentration above 5.6 × 10(2) CFU/m(3) and analyzed with pour plate method. The microorganisms present in the ambient room air interfere with precise quantification of Bacillus endospores when their concentration is relatively low. The results of this study may be helpful in critical assessment of the results obtained from monitoring the air for bacterial endospores.

Use of a foam spatula for sampling surfaces after bioaerosol deposition.

The present study had three goals: (i) to evaluate the relative quantities of aerosolized Bacillus atrophaeus spores deposited on the vertical, horizontal top, and horizontal bottom surfaces in a chamber; (ii) to assess the relative recoveries of the aerosolized spores from glass and stainless steel surfaces with a polyester swab and a macrofoam sponge wipe; and (iii) to estimate the relative recovery efficiencies of aerosolized B. atrophaeus spores and Pantoea agglomerans using a foam spatula at several different bacterial loads by aerosol distribution on glass surfaces. The majority of spores were collected from the bottom horizontal surface regardless of which swab type and extraction protocol were used. Swabbing with a macrofoam sponge wipe was more efficient in recovering spores from surfaces contaminated with high bioaerosol concentrations than swabbing with a polyester swab. B. atrophaeus spores and P. agglomerans culturable cells were detected on glass surfaces using foam spatulas when the theoretical surface bacterial loads were 2.88 x 10(4) CFU and 8.09 x 10(6) CFU per 100-cm(2) area, respectively. The median recovery efficiency from the surfaces using foam spatulas was equal to 9.9% for B. atrophaeus spores when the recovery was calculated relative to the theoretical surface spore load. Using a foam spatula permits reliable sampling of spores on the bioaerosol-exposed surfaces in a wide measuring range. The culturable P. agglomerans cells were recovered with a median efficiency of 0.001%, but staining the swab extracts with fluorescent dyes allowed us to observe that the viable cell numbers were higher by 1.83 log units than culturable organisms. However, additional work is needed to improve the analysis of the foam extracts in order to decrease the limit of detection of Bacillus spores and Gram-negative bacteria on contaminated surfaces.

[Effect of cerium nitrate supplementation to silver sulfathiazole preparations on survival of planctonic and attached to the dermis Staphylococcus aureus cells]. / Wplyw dodatku azotanu ceru do preparatów z sola srebrowa sulfatiazolu na przezywalnosc planktonowych i osiadlych na skórze komórek Staphylococcus aureus.

The purpose of this study was to evaluate the influence of preparations containing silver sulfathiazole, with or without cerium nitrate, on survival of Staphylococcus aureus. In the first step, sensitivity of the planctonic bacteria to the tested compounds was determined. Addition of cerium nitrate enhanced the antibacterial activity of silver sulfathiazole by 4 times, as evidenced by MIC and MBC values. For the estimation of antibacterial activity of the mentioned chemotherapeutic on attached bacteria in vitro model of an "infected wound" was applied. Sensitivity of bacteria attached to the dermis was lower than sensitivity of planctonic bacteria. Kinetics of the release of chemotherapeutic compounds incorporated into a collagen dressing was the most effective for the combination of silver sulfathiazole with cerium nitrate.

Kinetics of antibiotics release from ceramic implants.

Presented study describes kinetics of antibiotics release: cefazolin, gentamicin, netilmicin and vancomycin, from two types of ceramic implants: corundum and apatite cement prepared for osteosurgery. The experiments was based on our experimental model developed previously, in which the extraction of antibiotics from implants to polyurethane sponge was made for 3 days. The concentrations of antibiotics in the sponges were determined by spectrophotometric and biological methods. Among all ceramic materials tested, corundum implants with netilmicin and cement implants with gentamicin proved to be most efficacious regarding antibiotics release within 3 days of extraction to polyurethane sponge (yield of the release was 50% and 80% respectively). The lowest release was obtained in the case of cefazolin from cement disks (yield about 0.02%). The kinetics and effectiveness of antibiotics release from the ceramic implants tested depended on ceramic carrier and kind of the drug.