Öz
Objective: The aim of the study is to develop a new and automated method determining irreversible and reversible thiol oxidation products which are formed by the exposure of the plasma to oxidation and to measure the resistance of thiol groups to oxidation.
Material and Methods: The method is based on thiol-disulphide homeostasis measurement of plasma thiol groups before and after exposure to oxidative stress. According to the measurements, the levels of reversible thiol oxidation products (RTOP), irreversible thiol oxidation products (ITOP), and thiol oxidative stress index (TOSI=ITOP/RTOP) were determined.
Results: Plasma levels of ITOP were 24.02±12.1 μmol/L, levels of RTOP were 26.68±14.96 μmol/L and TOSI was 0.67±0.60 in the healthy control group. The level of ITOP of patients with lung and colon cancer were found to be significantly higher than the control group, while the level of RTOP was found to be significantly lower. When the parameter of TOSI which was used to determine the direction of the balance was examined, it was observed that the formation of ITOP was more dominant in both colon and lung cancer patients when compared to the control group.
Conclusion: Practical, inexpensive and semi-automatic spectrophotometric RTOP, ITOP and TOSI tests, developed by us for the first time, can be used to investigate many diseases associated with oxidative stress.