A NOVEL AND SEMIAUTOMATED ASSAY FOR THIOL OXIDATIVE STRESS INDEX: TOSI

Objective: The aim of the study is to develop a new andautomated method determining irreversible and reversible thioloxidation products which are formed by the exposure of theplasma to oxidation and to measure the resistance of thiolgroups to oxidation.Material and Methods: The method is based on thioldisulphidehomeostasis measurement of plasma thiol groupsbefore and after exposure to oxidative stress. According to themeasurements, the levels of reversible thiol oxidation products(RTOP), irreversible thiol oxidation products (ITOP), and thioloxidative stress index (TOSI=ITOP/RTOP) were determined.Results: Plasma levels of ITOP were 24.02±12.1 ?mol/L, levelsof RTOP were 26.68±14.96 ?mol/L and TOSI was 0.67±0.60 inthe healthy control group. The level of ITOP of patients withlung and colon cancer were found to be significantly higher thanthe control group, while the level of RTOP was found to besignificantly lower. When the parameter of TOSI which wasused to determine the direction of the balance was examined, itwas observed that the formation of ITOP was more dominant inboth colon and lung cancer patients when compared to thecontrol group.Conclusion: Practical, inexpensive and semi-automaticspectrophotometric RTOP, ITOP and TOSI tests, developed byus for the first time, can be used to investigate many diseasesassociated with oxidative stress.