METHODS
The goal of this study was to evaluate thiol/disulphide balance as a novel marker of OS in TB patients and to investigate changes occurring in the oxidant antioxidant system, TDH parameters (serum native thiol, total thiol and disulphide levels and disulphide/native thiol, disulphide/total thiol, native thiol/total thiol ratios) measurements in TB.
This study was performed with respect to the recommendations put forward via the Declaration of Helsinki. The study protocol was approved by the Ethical Committee and each participant gave written, informed consent. 50 patients with active lung tuberculosis referred to the Chest Diseases department of Harran University Medical Faculty Hospital (29 male, 21 female) and 50 healthy controls (29 male, 21 female) were included in the study.
Venous blood samples from the patients and healthy controls in the study were collected. Plasma blood samples were centrifuged at 1500 rpm for 10 min and serum was obtained. The separated serum was immediately placed in Eppendorf tubes and these samples were stored at −80°C until used.
Thiol/disulphide homeostasis evaluation had performed by a fully‑automatic method, developed by Erel and Neselioglu [12]. Disulphide bonds are first reduced with sodium borohydride to create functional thiol groups. Unused reducing agent, sodium borohydride, was removed with formaldehyde to prevent reduction of 5,5’‑dithiobis‑(2‑nitrobenzoic acid) (DTNB). All thiol groups, including reduced and native thiol groups, were later fixed by reactions with DTNB. Half of the difference between total thiol and native thiol determined the dynamic disulphide amount. After determining native and total thiols, disulphide levels, disulphide/total thiol, disulphide/native thiol, and native thiol/total thiol ratios were calculated.