Soluble Epoxide Hydrolase as an Important Player in Intestinal Cell Differentiation.

There is growing evidence that soluble epoxide hydrolase (sEH) may play a role in cell differentiation. sEH metabolizes biologically highly active and generally cytoprotective epoxyeicosatrienoic acids (EETs), generated from arachidonic acid metabolism by CYP epoxygenases (CYP2C and CYP2J subfamilies), to less active corresponding diols. We investigated the effect of sEH inhibitor (TPPU) on the expression of villin, CYP2C8, CYP2C9, CYP2J2, and sEH in undifferentiated and in vitro differentiated HT-29 and Caco2 cell lines. The administration of 10 µM TPPU on differentiated HT-29 and Caco2 cells resulted in a significant decrease in expression of villin, a marker for intestinal cell differentiation. It was accompanied by a disruption of the brush border when microvilli appeared sparse and short in atomic force microscope scans of HT-29 cells. Although inhibition of sEH in differentiated HT-29 and Caco2 cells led to an increase in sEH expression in both cell lines, this treatment had an opposite effect on CYP2J2 expression in HT-29 and Caco2 cells. In addition, tissue samples of colorectal carcinoma and adjacent normal tissues from 45 patients were immunostained for sEH and villin. We detected a significant decrease in the expression of both proteins in colorectal carcinoma in comparison to adjacent normal tissue, and the decrease in both sEH and villin expression revealed a moderate positive association. Taken together, our results showed that sEH is an important player in intestinal cell differentiation.

Toxicity of wastewater from health care facilities assessed by different bioassays.

OBJECTIVES: The purpose of this study was to determine toxicity of wastewater from hospitals in the Czech Republic using traditional and alternative toxicological methods. The pilot study comprised weekly dynamics of sewage ecotoxicity of treated wastewater from one hospital in two different seasons. A detailed investigation of wastewater ecotoxicity, genotoxicity and reprotoxicity followed in five different hospitals. METHODS: The seven following bioassays were used in this study: algal growth inhibition test (ISO 8692), Vibrio fischeri test (ISO 11348-2), Daphnia magna acute toxicity test (ISO 6341), Allium cepa assay, Ames test (OECD TG 471), Comet assay and YES/YAS assay. RESULTS: The wastewater ecotoxicity during one week showed no differences in separate working days, however, higher toxicity values were recorded in May compared to November. In the following study, samples from two of the five hospitals were classified as toxic, the others as non toxic. Genotoxicity has not been confirmed in any sample. In several cases, wastewater samples exhibited agonist activity to the estrogen and androgen receptors. CONCLUSION: The study demonstrated different levels of toxicity of treated hospital wastewater. Variable sensitivity of individual bioassays for tested wastewater samples was recognized. A more extensive study including proposal for improvement of hospital wastewater treatment within the Czech Republic can be recommended with the aim to decrease the discharge of toxic chemicals into the local sewage system and the environment.

Raman imaging of cellular uptake and studies of silver nanoparticles effect in BJ human fibroblasts cell lines.

Silver nanoparticles (AgNPs) have been widely studied for their beneficial antimicrobial effect and have been considered by some to be a safe ingredient, as penetration of metal nanoparticles through the skin in vivo has not been proven. However, AgNPs are becoming a commonly applied nanomaterial for surface modifications of medical products which come into contact with damaged skin. In our experiments, we tested two commercially available AgNPs samples manufactured by electrolysis. AFM was used to characterize tested AgNPs morphology and their mean particle size which was assessed as 30.6nm and 20.4nm. An important mechanism of AgNPs cytotoxicity is generation of reactive oxygen species (ROS), chemically reactive species containing oxygen. Although ROS occur in cell metabolism naturally, their overproduction can induce oxidative stress - imbalance between production and antioxidant defenses. This can be associated with cytotoxicity and DNA damage. Conventional in vitro tests were used to evaluate the cytotoxic potential and DNA damage in BJ human fibroblasts cell lines. We found that both tested AgNPs samples induced ROS generation and caused the DNA damage in fibroblasts. One of the key concerns about the association with cytotoxic or genotoxic responses of nanoparticles is the capability of these materials to penetrate through cellular membrane. Cellular uptake studies were performed using Raman imaging as a label-free microscopic technique. In combination with a univariate image analysis, results demonstrate cellular uptake and distribution of the AgNPs which were taken up by BJ cells within 24h of incubation in a growth medium. The study demonstrates the potential of Raman imaging to unambiguously identify and localize AgNPs in fixed cells.

The effect of silver nanoparticles and silver ions on mammalian and plant cells in vitro.

Silver nanoparticles (AgNPs) are the most frequently applied nanomaterials. In our experiments, we tested AgNPs (size 27 nm) manufactured by the Tollens process. Physico-chemical methods (TEM, DLS, AFM and spectrophotometry) were used for characterization and imaging of AgNPs. The effects of AgNPs and Ag(+) were studied in two experimental models (plant and mammalian cells). Human keratinocytes (SVK14) and mouse fibroblasts (NIH3T3) cell lines were selected to evaluate the cytotoxicity and genotoxicity effect on mammalian cells. Higher sensitivity to AgNPs and Ag(+) was observed in NIH3T3 than in SVK14 cells. AgNPs accumulated in the nucleus of NIH3T3 cells, caused DNA damage and increased the number of apoptotic and necrotic cells. Three genotypes of Solanum spp. (S. lycopersicum cv. Amateur, S. chmielewskii, S. habrochaites) were selected to test the toxicity of AgNPs and Ag(+) on the plant cells. The highest values of peroxidase activity and lipid peroxidation were recorded after the treatment of S. habrochaites genotype with AgNPs. Increased ROS levels were likely the reason for observed damaged membranes in S. habrochaites. We found that the cytotoxic and genotoxic effects of AgNPs depend not only on the characteristics of nanoparticles, but also on the type of cells that are treated with AgNPs.

Effect of Porphyrin Sensitizer MgTPPS4 on Cytoskeletal System of HeLa Cell Line-Microscopic Study.

Metalloporphyrins are an important group of sensitizers with a porphyrin skeleton. Their photophysical properties are significantly affected by the nature of the central ion. In this work, we focus on the mechanical properties of a cervix carcinoma cell line which underwent photodynamic treatment (PDT) with MgTPPS4 photosensitzer. Atomic force microscopy alongside confocal microscopy was used to quantify and qualify the structural characteristics before and after PDT. Cells before PDT showed a fine actin network and higher elasticity with the median of Young modulus 12.2 kPa. After PDT, the median of Young modulus was 13.4 kPa and a large redistribution in the actin network was observed.

Phthalocyanine-mediated Photodynamic Treatment of Tumoural and Non-tumoural cell lines.

This study deals with the use of cationic far-red absorbing photosensitizers (λ(max) ~740 nm) from the group of the phthalocyanines, in photodynamic therapy. The photosensitizers differed in their central atom, bearing either hydrogen, zinc or magnesium. These photosensitizers were tested in vitro on the tumour cell line HeLa (cervical cancer) and non-tumour cell line NIH3T3 (mouse fibroblast). The following tests were performed: measurement of reactive oxygen species production, viability testing, Comet assay and cell type detection (apoptotic, necrotic and living cells). The best results were achieved with zinc derivative at relatively low half-maximum inhibitory concentration (0.04 µM) and a total radiation dose of 15 J cm(-2).