A toxicological and genotoxicological indexing study of ambient aerosols (PM2.5-10) using in vitro bioassays.

This study evaluates the toxicity and genotoxicity levels of atmospheric particulate matter (PM) samples collected at several locations of a megacity (Istanbul, Turkey) with different urban and industrial characteristics. The ambient air samples, in the form of a coarse fraction of inhalable particulates, PM2.5-10, were collected on Teflon filters using a passive sampling method on a monthly basis during a one-year period. Later, they were extracted into both the lipophilic and hydrophilic phases using dimethyl sulfoxide (DMSO) and ultra-pure water, respectively. The obtained aqueous extracts were tested for acute toxicity and genotoxicity using the photo-luminescent bacterium Vibrio fischeri Microtox® and SOS Chromotest® assays, respectively. Statistically significant differences greater than background levels were obtained in both measurements, indicating the presence of toxic substances absorbed on particulate matter. The PM2.5-10 extracts identified significant seasonal and locational differences in the toxicity and genotoxicity levels. Local anthropogenic activities and factors were associated with the quantified higher levels. Finally, a qualitative inner comparison study of regional toxicity and genotoxicity indexes was suggested to provide a clearer picture of the pollution and risk levels (or occurrences) in the Istanbul urban area. In this indexing study, the threshold levels for the urban background and episodic occurrences of the toxicity and genotoxicity levels in PM2.5-10 samples were identified to be 1.11 TU (Toxicity Unit) and 8.73 TU and 0.72 IF (Induction Factor) and 1.38 IF, respectively.

Modifying enzymes related aminoglycoside: analyses of resistant Acinetobacter isolates.

Enzymatic modification of aminoglycosides by nucleotidyltransferases, acetyltransferases and/or phosphotransferases accounts for the majority of aminoglycoside-resistant Acinetobacter isolates. In this study, we investigated the relationship between aminoglycoside resistance and the presence of aminoglycoside-modifying enzymes in Acinetobacter baumannii clinical isolate groups with different resistance profiles. Thirty-two clinical A. baumannii isolates were included in this study. Acinetobacter isolates were divided into 4 groups according to results of susceptibility testing. The presence of genes encoding the following aminoglycoside-modifying enzymes; aph (3')-V1, aph (3')-Ia, aac (3)-Ia, aac (3) IIa, aac (6')-Ih, aac (6')-Ib and ant (2')-Ia responsible for resistance was investigated by PCR in all strains. The acetyltransferase (aac (6')-Ib, aac (3)-Ia) and phosphotransferase (aph (3')-Ia) gene regions were identified in the first group, which comprised nine imipenem, meropenem, and gentamicin-resistant isolates. The acetyltransferase (aac (6')-Ib, aac (3)-Ia), phosphotransferase (aph (3')-VI) and nucleotidyltransferase (ant2-Ia) gene regions were identified in the second group, which was composed of nine imipenem-resistant, meropenem-resistant and gentamicin-sensitive isolates. The acetyltransferase (aac (3)-Ia) and phosphotransferase (aph (3')-Ia) regions were identified in the fourth group, which comprised eight imipenem-sensitive, meropenem-sensitive and gentamicin-resistant isolates. Modifying enzyme gene regions were not detected in the third group, which was composed of six imipenem, meropenem and gentamicin-sensitive isolates. Our data are consistent with previous reports, with the exception of four isolates. Both acetyltransferases and phosphotransferases were widespread in A. baumannii clinical isolates in our study. However, the presence of the enzyme alone is insufficient to explain the resistance rates. Therefore, the association between the development of resistance and the presence of the enzyme and other components should be investigated further.

A statistical evaluation of the potential genotoxic activity in the surface waters of the Golden Horn Estuary.

The potential genotoxic activity in the surface waters of the Golden Horn Estuary was statistically evaluated utilizing a combination of appropriate parametric and non-parametric tests. The genotoxic activities that were associated with the water samples were determined by the SOS chromotest microplate assay. This assay utilizes ß-galactosidase activity, alkaline phosphatase activity, and four different solvent controls, to generate reliable results when corrected induction factors (CIF) are used as quantitative measurements of genotoxic activity. The CIF values were obtained from a total of 384 different genotoxic experiments that were grouped into subsets according to the respective seasons and the selected sampling locations. A total of 160 subsets were statistically compared to assess any possible differences between the pairs of groups, with 95% confidence limits. The findings of this study clearly indicate that some seasonal variations exist in the CIF values at several sampling sites. However, no potentially hazardous impact to the aquatic environment was found in the estuarine system.