Air pollution effects on the activity of antioxidant enzymes in Nerium oleander and Robinia pseudo acacia plants in Tehran

The air pollution effects on the activity of antioxidant enzymes were investigated on Nerium oleander and Robinla pseudo acacia in Tehran. Considering the information obtained from the Department of the Environment of Iran, Sorkh Hesar Park as well as South Azadi were selected as two sampling sites representing the unpolluted and polluted area respectively. A number of plant leave samples were collected from both sampling sites simultaneously. The activity of plant enzymes including peroxidase, catalase and ascorbate peroxidase was investigated using spectrophotometric methods. A higher level of peroxidase and catalase enzymes were measured in both plant samples collected from polluted area. However, this higher level was only statistically significant for the activity of peroxidase enzyme in Robinia pseudo acacia plants compare of to the control group (p < 0.05). The lower level of ascorbate peroxidase was observed in Nerium oleander plant leaves collected from the contaminated sampling site (p < 0.05), but though, the activity of this enzyme in Robinia pseudo acacia did not change significantly. The overall plant injury symptoms found in this study demonstrated that both Nerium oleander and Robinia pseudo acacia have a potential to be considered as effective bioindicators to reflect the environmental air quality in polluted areas

An integrated in vitro approach for toxicity testing of airborne contaminants

While it is possible to establish the chemical composition of air pollutants through conventional air sampling and analytical techniques, such data do not provide direct measures of toxicity and the potential mechanisms that induce adverse effects. The aim of this study was to optimize in vitro methods for toxicity testing of airborne contaminants. An integrated approach was designed in which appropriate exposure techniques were developed. A diversified range of in vitro assays using multiple human cell systems were implemented. Direct exposure of cells to airborne contaminants was developed by culturing cells on porous membranes in conjunction with a horizontal diffusion chamber system. Concentration-response curves were generated allowing the measurement of toxicity endpoints. Regression analysis indicated a significant correlation between in vitro and published in vivo toxicity data for the majority of selected chemical contaminants. Airborne IC50 values were calculated for selected volatile organic compounds (xylene, 5350 ± 328 ppm > toluene, 10500 ± 527 ppm) and gaseous contaminants (NO2, 11 ± 3.54 ppm > SO2, 48 ± 2.83 ppm and > NH3, 199 ± 1.41 ppm). Results of this study indicate the significant potential of in vitro methods as an advanced technology for toxicity assessment of airborne contaminants. Copyright © Taylor & Francis Group, LLC

Xenobiotic metabolism in differentiated human bronchial epithelial cells

Differentiated human bronchial epithelial cells in air liquid interface cultures (ALI-PBEC) represent a promising alternative for inhalation studies with rodents as these 3D airway epithelial tissue cultures recapitulate the human airway in multiple aspects, including morphology, cell type composition, gene expression and xenobiotic metabolism. We performed a detailed longitudinal gene expression analysis during the differentiation of submerged primary human bronchial epithelial cells into ALI-PBEC to assess the reproducibility and inter-individual variability of changes in transcriptional activity during this process. We generated ALI-PBEC cultures from four donors and focussed our analysis on the expression levels of 362 genes involved in biotransformation, which are of primary importance for toxicological studies. Expression of various of these genes (e. g., GSTA1, ADH1C, ALDH1A1, CYP2B6, CYP2F1, CYP4B1, CYP4X1 and CYP4Z1) was elevated following the mucociliary differentiation of airway epithelial cells into a pseudo-stratified epithelial layer. Although a substantial number of genes were differentially expressed between donors, the differences in fold changes were generally small. Metabolic activity measurements applying a variety of different cytochrome p450 substrates indicated that epithelial cultures at the early stages of differentiation are incapable of biotransformation. In contrast, mature ALI-PBEC cultures were proficient in the metabolic conversion of a variety of substrates albeit with considerable variation between donors. In summary, our data indicate a distinct increase in biotransformation capacity during differentiation of PBECs at the air-liquid interface and that the generation of biotransformation competent ALI-PBEC cultures is a reproducible process with little variability between cultures derived from four different donors

AIR POLLUTION EFFECTS ON THE ACTIVITY OF ANTIOXIDANT ENZYMES IN NERIUM OLEANDER AND ROBINIA PSEUDO ACACIA PLANTS IN TEHRAN

The air pollution effects on the activity of antioxidant enzymes were investigated on Nerium oleander and Robinia pseudo acacia in Tehran. Considering the information obtained from the Department of the Environment of Iran, Sorkh Hesar Park as well as South Azadi were selected as two sampling sites representing the unpolluted and polluted area respectively. A number of plant leave samples were collected from both sampling sites simultaneously. The activity of plant enzymes including peroxidase, catalase and ascorbate peroxidase was investigated using spectrophotometric methods. A higher level of peroxidase and catalase enzymes were measured in both plant samples collected from polluted area. However, this higher level was only statistically significant for the activity of peroxidase enzyme in Robinia pseudo acacia plants compare of to the control group (p < 0.05). The lower level of ascorbate peroxidase was observed in Nerium oleander plant leaves collected from the contaminated sampling site (p < 0.05), but though, the activity of this enzyme in Robinia pseudo acacia did not change significantly. The overall plant injury symptoms found in this study demonstrated that both Nerium oleander and Robinia pseudo acacia have a potential to be considered as effective bioindicators to reflect the environmental air quality in polluted areas

AIR POLLUTION EFFECTS ON THE ACTIVITY OF ANTIOXIDANT ENZYMES IN NERIUM OLEANDER AND ROBINIA PSEUDO ACACIA PLANTS IN TEHRAN

The air pollution effects on the activity of antioxidant enzymes were investigated on Nerium oleander and Robinia pseudo acacia in Tehran. Considering the information obtained from the Department of the Environment of Iran, Sorkh Hesar Park as well as South Azadi were selected as two sampling sites representing the unpolluted and polluted area respectively. A number of plant leave samples were collected from both sampling sites simultaneously. The activity of plant enzymes including peroxidase, catalase and ascorbate peroxidase was investigated using spectrophotometric methods. A higher level of peroxidase and catalase enzymes were measured in both plant samples collected from polluted area. However, this higher level was only statistically significant for the activity of peroxidase enzyme in Robinia pseudo acacia plants compare of to the control group (p < 0.05). The lower level of ascorbate peroxidase was observed in Nerium oleander plant leaves collected from the contaminated sampling site (p < 0.05), but though, the activity of this enzyme in Robinia pseudo acacia did not change significantly. The overall plant injury symptoms found in this study demonstrated that both Nerium oleander and Robinia pseudo acacia have a potential to be considered as effective bioindicators to reflect the environmental air quality in polluted areas

Troubleshooting methods for toxicity testing of airborne chemicals in vitro

Toxicology studies of adverse effects induced by inhaled chemicals are technically challenging, due to the requirement of highly controlled experimental conditions needed to achieve reproducible and comparable results. Therefore, many considerations must be fulfilled before adopting in vitro bioassay test systems for toxicity screening of airborne materials. However, recent methodological and technical breakthroughs of in vitro methods have the potential to fulfil the essential requirements of toxicity testing for airborne chemicals. Technology has now become available that allows cells to be cultured on permeable microporous membranes in transwell or snapwell inserts providing a very close contact between target cells and test atmospheres to study the cellular interactions caused by airborne chemical exposures without any interfering culture medium. Using a direct exposure technique at the air-liquid interface, target cells can be continuously exposed to airborne chemicals on their apical side, while being nourished from their basolateral side. Test atmospheres with different physicochemical characteristics such as gases, vapours, solid and liquid aerosols and more recently nanoaerosols, can be delivered into human target cells using static and/or direct dynamic exposure methods. Therefore, toxicological risk assessments of airborne chemicals and even complex atmospheres can be achieved using in vitro test methods in parallel with real-time air monitoring techniques to fulfil the general regulatory requirements of newly developed chemical or pharmaceutical products with the potential for inhalational exposure. In this review current toxicological methods for toxicity testing of inhaled chemicals are presented. Further, to demonstrate the potential application of in vitro methods for studying inhalation toxicity, more advanced exposure techniques developed for toxicity screening of airborne chemicals are discussed. © 2010 Elsevier Inc