Background: Wastewater contains a variety of pathogens and bio -aerosols generated during the wastewater treatment process, which could be a potential health risk for exposed individuals. This study was carried out to detect Legionella spp. in the bio -aerosols generated from different processes of a wastewater treatment plant (WWTP) in Isfahan, Iran, and the downwind distances. Materials and Methods: A total of 54 air samples were collected and analyzed for the presence of Legionella spp. by a nested- polymerase chain reaction (PCR) assay. A liquid impingement biosampler was used to capture bio -aerosols. The weather conditions were also recorded. Results: Legionella were detected in 6% of the samples, including air samples above the aeration tank (1/9), belt filter press (1/9), and 250 m downwind (1/9). Conclusion: The result of this study revealed the presence of Legionella spp. in air samples of a WWTP and downwind distance, which consequently represent a potential health risk to the exposed individuals.

Background: During adolescence, sex hormones play an important role in regulating proliferation, differentiation, maturation, and the scheduled death of chondrocytes. Although some studies have reported the regulatory role of estrogen in the development and progression of cartilage, some of the mechanisms still remain unclear, including the role of estrogen in the expression of cartilage-specific genes in chondrogenesis process, which we cover in this study. Materials and Methods: In the present study, we used adipose-derived stem cells (ADSCs) to differentiate into cartilage. Differentiated cartilage cells were used in the control (without estrogen E2 in the culture medium) and experimental (with estrogen in the culture medium) groups to evaluate the expression of type II collagen and aggrecan as chondrogenic genes markers, with -real-time polymerase chain reaction technique. Results: Our results indicated that estrogen leads to inhibition of type II collagen gene expression and reduction of aggrecan gene expression. Conclusion: Therefore, estrogen probably has negative effects on chondrogenesis process of ADSCs.