Toxicity of arsenic on isolated human lymphocytes: The key role of cytokines and intracellular calcium enhancement in arsenic-induced cell death

Arsenic (As) is a semi-metal which causes health problems in human, and immune system has been documented as one of the main target of arsenic toxicity. Apoptosis has a crucial role in regulation of immune system, but it can also have an important role in As immune suppression. So, we decided to assess the comprehensive mechanism of As cytotoxic effect on lymphocytes isolated from human blood. We determine the direct effect of arsenic on human lymphocytes which have a key role in immune system functionality. To evaluate the mechanism of arsenic toxicity on human lymphocytes, we use accelerated cytotoxicity mechanisms screening (ACMS) technique. Lymphocytes were isolated from blood of healthy persons using Ficoll-paque PLUS standard method. Following treatment of human lymphocytes with 0.05-50 μM of arsenic for 12 h, cell viability was measured. For determination of mechanistic parameters, isolated human lymphocytes incubated with 1/2IC5012h (7.5 μM), IC5012h (15 μM) and 2IC5012h (30 μM) for 2, 4 and 6 h. The results of this study demonstrate arsenic-associated apoptosis in human lymphocytes is mainly through enhancement of intracellular calcium which causes oxidative stress and following adverse effect on lymphocytes organelles (like mitochondria and lysosome). Involvement of cellular proteolysis, activation of caspase-3, lipid peroxidation and stimulation of cytokines (IL2, INF-gamma and TNF-alpha) production were also associated with arsenic induced lymphocyte toxicity.

Effects of photopolymerisation on genotoxicity of composite adhesives in the comet assay

Certain in vivo studies have shown that the application of adhesives directly onto the open pulp or on a thin layer of dentin causes inflammation and pulpal abscesses. This reaction is related to toxic effects of monomers from adhesives. It has been confirmed that after proper illumination the adhesives become less toxic. The aim of the study was to examine genotoxicity of non-polymerised, partly polymerised and polymerised adhesives on isolated human lymphocytes using the alkaline Comet assay. Adper Single bond2 and Adper Easy One/3M ESPE adhesive photopolymerisation was performed by Elipar Highlight 3M ESPE halogen lamp for 0, 10 and 40 sec, at final concentrations of 100, 200, 500 and 1000 ?g/mL. With both adhesives, photopolymerisation at 0 and 10 seconds showed statistically significant increase in DNA damage in comparision to the negative control (solvent). On the other hand, after 40 seconds of photopolymerisation of both adhesives in all tested concentrations, the degree of DNA damage in Comet assay had no significant difference (P>0.05, ?2 test) compared to the negative control. Therefore, only the 40 seconds of photopolymerisation prevented genotoxic effects of both adhesives in the Comet assay.

The Investigation of DNA Damage Induced by Adrenaline in Human Lymphocytes in Vitro/Ispitivanja Oštećenja DNK Izazvanih Adrenalinom U Limfocitima Čoveka in Vitro

Adrenaline is a neurotransmitter and hormone that plays an important role in physiological regulatory mechanisms. The objective of this study was to assess primary DNA damage in isolated human lymphocytes exposed to adrenaline using the in vitro comet assay. Dose-response of human lymphocytes was determined at concentration range of adrenaline from 0.01 μM to 300 μM for various treatment times (1h, 2h, 4h and 24h). The obtained results showed that adrenaline induced DNA damage at concentration range from 5 μM to 300 μM after 1h, 2h and 4h of treatment. The slightest DNA damage was observed after 24 h of adrenaline treatment - only the highest concentrations of adrenaline (150 μM and 300 μM) caused increased level of DNA damage. In order to evaluate the potential contribution of reactive oxygen species (ROS) in adrenaline-induced DNA damage we used antioxidants catalase (100 IU/mL and 500 IU/mL) and quercetin (100 μM and 500 μM). Co-treatment of lymphocytes with adrenaline (300 μM) and antioxidants for 1 h, significantly reduced the quantity of DNA in the comet tails. Therefore, it can be concluded that adrenaline exhibits genotoxic effects mainly through induction of reactive oxygen species and that some of the DNA damage is repaired during the first four hours following the treatment with adrenaline.