Cemile Bicer

Thiol/disulfide homeostasis in patients with idiopathic recurrent pregnancy loss assessed by a novel assay: Report of a preliminary study

To evaluate the relationship between idiopathic recurrent pregnancy loss (RPL) and oxidative stress (OS) by means of thiol/disulfide homeostasis via a novel technique.

A New Oxidative Stress Marker for Thiol-Disulphide Homeostasis in Seasonal Allergic Rhinitis:

Background Reactive oxygen species has a crucial role in the pathogenesis of many diseases. Reactive oxygen species has been effectively documented in patients with asthma, but very little research has been reported in subjects with allergic rhinitis. Objectives To investigate thiol (SH)–disulfide (SS) homeostasis, a new oxidative stress marker present in patients with seasonal allergic rhinitis (SAR). Methods A total of 64 subjects, including 32 patients with SAR and 32 healthy controls, were included in the study. We measured the SH levels as a marker of antioxidant protection and SS as a marker related to oxidant stress. Sera specimens were taken from patients with SAR during exacerbation and during asymptomatic time periods. In addition, sera samples from the control group were also obtained during the pollen season to compare with those from patients with SAR. Results In patients with SAR, during exacerbation periods, SH, SS, % SS/SH, % SS to total SH (TT), and % SH/TT were significantly different (p < 0.05) than in patients with SAR during asymptomatic periods. Although SS was significantly higher in patents with SAR during exacerbation periods, SH was significantly higher in patients with SAR during asymptomatic periods. Patients with SAR during asymptomatic periods and the control group did not significantly differ (p > 0.05) regarding SH, SS, TT, % SS/SH, % SS/TT, and % SH/TT. Conclusion SAR is a disorder that elevates systemic oxidative stress and reduces antioxidant enzyme activities. Our results shed light on the etiopathogenesis of the disease and can help develop new therapeutic approaches.

A novel method for determining the relation between nasal polyposis and oxidative stress: the thiol/disulphide homeostasis

Abstract Conclusion: It is thought that oxidative stress may be the major cause of the increase in the oxide thiol form in the study group. The relationship between oxidative stress status and dynamic thiol/disulphide in nasal polyposis now needs to be investigated. Objectives: The purpose of this study was to evaluate the relation between nasal polyposis and thiol/disulphide homeostasis, used as a marker of oxidative stress, by measuring that exchange using a novel technique. Materials and methods: The study group consisted of 40 patients (mean age = 46.75 ± 13.92 years) with bilateral nasal polyposis patients admitted to the hospital. The control group consisted of 31 (mean age = 43.20 ± 5.68 years) age, sex, and body mass index matched healthy subjects. Thiol/disulphide homeostasis concentrations were measured using a newly-developed method (Erel & Neselioglu). Results: Native thiol and total thiol levels were lower in the study group compared to the control group (native thiol = 415.8 ± 69.1 μmol/L vs 448.7 ± 37.5 μmol/L, p < 0.05; total thiol = 449.02 ± 72.0 μmol/L vs 477.28 ± 44.5 μmol/L, p < 0.05, respectively). Disulphide level and the disulphide/native thiol and disulphide/total thiol ratios were higher in the study group compared to the control group (disulphide = 16.58 ± 5.04 μmol/L vs 14.28 ± 5.3 μmol/L, p < 0.05; disulphide/native thiol ratio = 4.07 ± 1.52% vs 3.14 ± 1.04%, p < 0.05, disulphide/total thiol ratio = 3.73 ± 1.23% vs 2.94 ± 0.92%, p < 0.05, respectively).

A Novel Tool for the Assessment Oxidative Stress in Age-Related Macular Degeneration: Thiol/Disulfide Homeostasis Revisited

ABSTRACT Purpose: To investigate thiol/disulfide status using a novel automated assay in patients with age-related macular degeneration (AMD) compared to age-matched healthy controls. Methods: A total of 64 AMD patients [51 (79%) non-exudative, 13 (21%) exudative AMD] and 21 age-matched healthy control subjects were enrolled in this study. Plasma total thiol, native thiol, disulfide levels were measured and native thiol/disulfide ratio (TDR) was calculated using a novel spectrophotometric assay. Results: Patients with AMD had significantly lower levels of total thiol (434.8 ± 7.0 μmol/L vs. 472.2 ± 7.9 μmol/L, p < 0.001), native thiol (393.6 ± 6.5 μmol/L vs. 437.5 ± 7.1 μmol/L, p = 0.004) compared to healthy controls. However, plasma disulfide levels were higher in AMD patients (20.6 ± 0.9 μmol/L vs. 17.3 ± 1.3 μmol/L, p = 0.113) compared to healthy controls. The TDR was not statistically different between the early AMD group and healthy controls (24.2 ± 2.3 vs. 29.5 ± 3.1, p = 0.345). However, intermediate and advanced stage AMD groups had significantly lower levels of TDR compared to healthy controls (21.6 ± 2.6 vs. 29.5 ± 3.1, p = 0.023 and 20.3 ± 1.2 vs. 29.5 ± 3.1, p = 0.005, respectively). Native TDR was significantly lower in patients with exudative and non-exudative AMD (19.9 ± 2.3 vs. 29.5 ± 3.1, p = 0.024 and 21.8 ± 1.14 vs. 29.47 ± 3.1 respectively, p = 0.011). Conclusion: A greater extent of thiol consumption occurred in AMD patients compared to age-matched healthy controls. However, despite the similar levels of total thiol levels between several grades of AMD, the plasma native TDR value was decreased in accordance with the severity of the disease, which reflected the disease grade better.

Dynamic thiol/disulfide homeostasis in children with attention deficit hyperactivity disorder and its relation with disease subtypes

BACKGROUND The aim of this study was to evaluate a novel oxidative stress marker (thiol/disulfide homeostasis) in attention deficit hyperactivity disorder (ADHD) children for the first time in literature. METHODS Ninety children with ADHD diagnosed according to DSM-V and as control group, 65 healthy children were included to the study. Native thiol, total thiol, disulfide, disulfide/native thiol, disulfide/total thiol were compared between the groups. RESULTS Total and native thiol levels were significantly higher whereas the disulfide/native thiol ratios were significantly lower in children with ADHD. ADHD combined type appeared to have higher disulfide, disulfide/native thiol and disulfide/total thiol ratios compared to other subtypes. Disulfide levels of the males with ADHD were significantly higher than those of the females with ADHD. CONCLUSION This study suggests that thiol/disulfide homeostasis is abnormal in children with ADHD. It may be used as a novel OS marker in ADHD children because it is easy, practical, fully automated and relatively inexpensive.

Dynamic Thiol/Disulphide Homeostasis in Patients With Fibromyalgia

Objectives This study aims to investigate dynamic thiol/disulphide homeostasis in patients with fibromyalgia syndrome (FMS). Patients and methods Fifty female patients with FMS (mean age 40.5±7.2 years; range 21 to 55 years) and 40 healthy female controls (mean age 39±9.4 years, range 22 to 55 years) were included in the study. Pain visual analog scale, tender points, Fibromyalgia Impact Questionnaire, and Beck Depression Inventory were evaluated. Age, body mass index (BMI), and symptom durations were also recorded. Native thiol, disulphide and total thiol levels were measured with a novel automated method. Results Serum disulphide levels were 14.7±3.4 μmol/L and 22.2±3.6 μmol/L in the FMS and control groups, respectively (p<0.001). Native thiol levels were 452.1±33.8 μmol/L and 433.5±37.6 μmol/L in the FMS and control groups, (p=0.015), while total thiol levels were 481.7±35.6 μmol/L and 477.5±38.9 μmol/L in the FMS and control groups, respectively (p=0.593). In the FMS group, disulphide/native thiol percent ratios and disulphide/ total thiol percent ratios were statistically significantly lower and native/total thiol percent ratios were statistically significantly higher than those of the control group. There were no correlations between serum thiol/disulphide profiles and pain scores & clinical variables in patients with FMS. Conclusion Because of the decreased disulphide and increased native thiol levels, the thiol/disulphide balance has shifted to the reductive side. This metabolic disturbance may have a role in the pathogenesis of FMS.

Thiol-disulfide homoestasis in pregnancies with fetal growth restriction

Abstract Aim: To investigate the role of dynamic thiol-disulfide homeostasis in preeclamptic and idiopathic fetal growth restricted (FGR) pregnancies. Material and method: In this prospective case-control study, a total of 110 singleton pregnancies with FGR (study group) (51 preeclamptic and 59 idiopathic FGR’s cases) were compared with 68 healthy pregnant controls at the same gestational weeks (control group). For serum disulfide-thiol homeostasis, a newly used method described by Erel and Neselioglu was used. Results: Serum native thiol and total thiol levels were lower in FGR pregnancies (285.63 ± 55.92 µmol/L, 324.41 ± 44.18 µmol/L, respectively) than control group (324.41 ± 44.18 µmol/L, 362.98 ± 51.43 µmol/L, p < .001, p = .004, respectively). In subgroup analysis, only preeclamptic FGR’s have lower native and total thiol levels (254.41 ± 59.55, 324.41 ± 44.18 µmol/L, respectively) compare to both idiopathic FGR’s and control’s. There was no difference in native and total thiol levels with idiopathic FGR’s with controls. Idiopathic FGR’s have higher levels of disulfide than preeclamptic FGR’s (21.72 ± 17.72 versus 16.80 ± 11.20 µmol/L). The serum albumin and total protein levels were positively and spot urine protein/creatinine ratio, 24-h urine protein levels were negatively correlated with native thiol and total thiol levels. Conclusion: The balance of thiol-disulfide homeostasis was shifted and native and total thiol levels were decreased only in preeclamptic FGR pregnancies. The serum disulfide level was increased in idiopathic FGR pregnancies compare to preeclamptic FGR pregnancies which may be a sign of oxidative stress in idiopathic FGR pregnancies with normal thiol pool.

Oxidative Status in Patients with Benign Paroxysmal Positional Vertigo

OBJECTIVE Benign paroxysmal positional vertigo (BPPV) is the most frequent peripheral vestibular disorder and is particularly seen among older patients suffering from vertigo. The brief vertigo attacks in and imbalance symptoms of BPPV are caused by freely floating otoconia within the semicircular canals. The aim of this prospective study was to evaluate the role of oxidative stress, using native thiol/disulfide (SH/SS) homeostasis as a novel indicator, in the etiology of BPPV. MATERIALS AND METHODS The 62 participants in the study included 31 patients with BPPV and, as the control group, 31 healthy individuals without any cochleovestibular disorders. RESULTS Patients with BPPV initially had significantly lower native SH levels and significantly lower SH/total thiol (TT) ratios, as well as significantly higher SS/SH and SS/TT ratios, than the healthy controls. After successful treatment of their vertigo, which was confirmed based on the results obtained from the second blood sample, patients with BPPV still had lower SH levels and SH/TT ratios and significantly higher SS/SH and SS/TT ratios than the healthy controls. CONCLUSION Our results suggest a role of oxidative stress in the development of BPPV, through both calcium metabolism and the direct toxic effects of free oxygen radicals, including the triggering of apoptosis.

Thiol/Disulfide Balance in Patients with Familial Hypercholesterolemia

Objective Herein, we investigated the balance of thiol/disulfide, with the hypothesis that the balance between disulfides and thiols, which are natural antioxidants, might be disrupted in patients with familial hypercholesterolemia, which eventually leads to endothelial damage. Methods In this study, we evaluated 51 patients diagnosed with familial hypercholesterolemia and 81 healthy subjects. Blood samples were taken from the patients after a minimum of 12 hours of fasting; samples were immediately centrifuged, stored in Eppendorf tubes, and preserved at −80°C. Results This study found that thiol levels are significantly lower in patients with familial hypercholesterolemia, whereas disulfide levels are higher (independent of age, gender, and body mass index). This means that in such patients, the thiol/disulfide balance changes in favour of disulfide. Conclusions In this study, we found that the thiol/disulfide balance in patients with familial hypercholesterolemia is disrupted in favour of disulfide.