Dynamic thiol-disulfide homeostasis (TDH) is a new area has begun to attract more scrutiny. Dynamic TDH is reversal of thiol oxidation in proteins and represents the status of thiols (-SH) and disulfides (-S-S-). Organic compounds containing the sulfhydryl group is called thiol, composed of sulfur and hydrogen atoms. Disulfides are the most important class of dynamic, redox responsive covalent bonds build in between two thiol groups. For many years, thiol levels were analyzed by several methods. During last years, measurements of disulfide levels have been analyzed by a novel automated method, developed by Erel and Neselioglu. In this method, addition to thiol-termed as native thiol- levels, disulfide levels were also measured and sum of native thiol and disulfide levels were termed as total thiol. Therefore, TDH was begun to be understood in organism. In healthy humans, TDH is maintained within a certain range. Dysregulated dynamic TDH has been implicated several disorders with unknown etiology. A growing body of evidence has demonstrated that the thiol-disulfide homeostasis is involved in variety diseases, such as diabetes mellitus, hypertension, non-small cell lung cancer, Familial Mediterranean fever, inflammatory bowel diseases, occupational diseases, gestational diabetes mellitus and preeclampsia. These results may elucidate some pathogenic mechanism or may be a predictor indicating diagnostic clue, prognostic marker or therapeutic sign. In conclusion, protection of the thiol disulfide homeostasis is of great importance for the human being. Evidence achieved so far has proposed that thiol-disulfide homeostasis is an important issue needs to elucidate wholly.

Background: Rosacea is the chronic inflammatory disease of the facial skin. Although its etiology is not clear yet, inflammatory processes triggered by oxidative stress and oxidation of lipids have been suggested to have a role. While studies on the relationship between inflammation and oxidative stress are ongoing, thiol metabolism and its role in oxidative stress have also begun to be investigated. Thiols are among the key molecules of protein metabolism in the organism and they are firstly consumed antioxidants in case of oxidative stress. Thiols regulate intracellular redox metabolism and protect keratinocytes against the results of oxidative alterations in the stratum corneum. There is a balance known as dynamic thiol/disulfide homeostasis between thiols and their oxidized forms; disulfides. Aim: This study aimed to determine the effects of oxidative stress on protein metabolism in rosacea patients by investigating thiol/disulfide homeostasis using a newly developed and fully automated method. Determination of plasma thiol levels provides important clues regarding the extent of free radical-mediated oxidation of proteins causing damage in rosacea. Methods: The study included 50 rosacea patients who were diagnosed clinically or histopathologically with rosacea and 42 age- and gender-matched healthy controls. Serum plasma levels of native thiol, total thiol, and disulfide were determined. The following ratios were calculated: Disulfide/native thiol ratio, disulfide/total thiol ratio, and native thiol/total thiol ratio. Results:The mean age was 41.8±10.5 in the rosacea patients (35 females) and 42.5±10.3 years in the control group (33 females). The mean disulfide level was found to be significantly higher in the rosacea patients than in the control group (23.4±5.5 µM/L and 17.3±6.2µM/L, respectively; p < 0.001). The mean disulfide/native thiol ratio (0.055±0.016 vs. 0.041±0.017) and the mean disulfide/total thiol ratio (0.049±0.012 vs.0.037±0.013) were significantly higher and the mean native thiol/total thiol ratio (0.884±0.118 vs. 0.923±0.027) was significantly lower in the patients as compared with the controls (p < 0.05 for all). Conclusion: In rosacea patients, the thiol/disulfide balance was observed to shift towards disulfides, which could be considered an indicator of oxidative stress in rosacea.

Oxidative stress represents the imbalance between oxidants and antioxidants and has been associated with a wide range of diseases. Thiols are the most important compounds in antioxidant defense. There is an equilibrium between thiols and their oxidized forms, disulfides, known as dynamic thiol-disulfide homeostasis (TDH). In 2014, Erel and Neselioglu developed a novel automated assay to measure thiol and disulfide levels. Subsequently, many researchers have used this simple, inexpensive and fast method for evaluating TDH in various disorders. We have reviewed the literature on the role of TDH in skin diseases. We identified 26 studies that evaluated TDH in inflammatory diseases (psoriasis, seborrheic dermatitis, atopic dermatitis, vitiligo, acne vulgaris and rosacea), allergic diseases (acute and chronic urticaria) and infectious diseases (warts, pityriasis rosea and tinea versicolor). The results are heterogeneous, but in most cases indicate changes in TDH that shifted toward disulfides or toward thiols, depending on the extent of oxidative damage.

Background/Aims: Pancreatic steatosis (PS) is a generally used term to define accumulation of fat in the pancreas. In theory PS may be able to affect the exocrine function of pancreas. In this study we aimed to determine the effect of PS on exocrine pancreas function. Materials and Methods: Forty-three patients with PS determined by 3 tesla magnetic resonance imaging (MRI) and 48 patients without PS were included in this study. Patients with PS were classified as group 1 and control patients were classified as group 2. Fecal elastase-1 levels were determined. Fecal elastase-1 levels Results: Fecal elastase-1 levels was significantly lower in group 1 compared to group 2 (319.76±45.7 vs 549.31±69.4, respectively, p=0.003). Proportion of patients with EPI was significantly higher in group 1 than group 2 (35.5% vs 12% p=0.042). There were no significant differences in terms of severity or the anatomic distribution of PS in patients with PS with EPI based on MRI (p=0.052, p=0.198, p=0.405) Conclusion: Current study demonstrates that PS can cause EPI. Cite this article as: Tahtacı M, Algın O, Karakan T, et al. Can pancreatic steatosis affect exocrine functions of pancreas? Turk J Gastroenterol 2018; 29: 588-94.

Background: A crucial balance exists between oxidant and antioxidant mechanisms in the functional immune system. We aimed to evaluate the contributions of balance between these systems to coronavirus disease 2019 (COVID‐19), a devastating pandemic caused by viral infection.Method: We analyzed serum oxidant and antioxidant stress parameters according to the clinical and demographic characteristics of children and adults with COVID‐19 and compared them against the values of healthy controls. Serum native thiol (NT), total thiol (TT), disulfide, total antioxidant status, total oxidant status, and ischemia‐modified albumin levels were evaluated and compared between groups.Results: A total of 79 children and 74 adults were evaluated in the present study, including 46 children and 40 adults with COVID‐19, 33 healthy children, and 34 healthy adults. TT, NT, and disulfide levels were significantly lower in the adult COVID‐19 group than in all other groups (p = .001, p = .001, and p = .005, respectively). Additionally, TT and NT levels were significantly lower in both pediatric and adult COVID‐19 cases with severe disease course than mild/moderate course. TT and NT levels were identified as predictors for the diagnosis of the adult COVID‐19 cases and as independent predictors for disease severity in both children and adults with COVID‐19.Conclusion: Parameters that reveal the oxidant and antioxidant capacity, including TT and NT, appear to be good candidates for the accurate prediction of the clinical course among patients with COVID‐19.