Salim Neselioglu

A novel and automated assay for thiol/disulphide homeostasis

OBJECTIVES To develop a novel and automated assay determining plasma thiol/disulphide homeostasis, which consists of thiol-disulphide exchanges. DESIGN AND METHODS Native thiol and total thiol concentrations were synchronously measured as a paired test. In the first vessel, the amount of native thiol groups was measured by a modified Ellman reagent. At the parallel run, first, dynamic disulphide bonds were reduced to free thiol groups by NaBH(4). The unused reductant remnants were completely removed by formaldehyde. Thus, the total thiol amount could be accurately measured. Mercaptoethanol solutions were used as calibrators. The half value of the difference between total thiol and native thiol amounts gave the disulphide bond amount. RESULTS No separation step for the assay was needed. All processes were performed using an automated analyser within about 10 min. Plasma disulphide levels were 17.29±5.32 μmol/L, native thiol levels were 397±62 μmol/L and disulphide/native thiol per cent ratios were 4.32±1.49 in healthy subjects. Plasma disulphide levels were higher in patients with degenerative diseases and lower in patients with proliferative diseases. CONCLUSION An easy, inexpensive, practical, fully automated and also optionally manual spectrophotometric assay can be used to determine plasma dynamic thiol/disulphide homeostasis.

A novel oxidative stress marker in acute myocardial infarction; thiol/disulphide homeostasis.

BACKGROUND The aim of this study was to investigate a novel oxidative stress marker (thiol/disulphide homeostasis) in patients with acute myocardial infarction (AMI) and compare the results with healthy controls for the first time in literature. METHODS A total of 450 participants including 300 patients with AMI and 150 healthy individuals were included in the study. Left ventricular ejection fraction, body mass index, peak troponin I levels, triglyceride, total cholesterol, low-density lipoprotein, high-density lipoprotein (HDL), native thiol, total thiol, and disulphide as well as disulphide/native thiol and disulphide/total thiol ratios were compared between the groups. RESULTS There were significant differences between AMI patients and the controls for left ventricular ejection fraction and troponin, HDL, native thiol, total thiol, and disulphide levels as well as disulphide/native thiol and disulphide/total thiol ratios (P < .05). Stepwise logistic regression model indicated that HDL (odds ratio [OR] = 0.923, P < .001) and disulphide levels (OR = 0.548, P < .001) and disulphide/total thiol ratio (OR = 0.356, P < .001) were significantly and independently related to AMI. The cutoff value of disulphide/total thiol ratio percentage on admission to predict AMI in all population was 4.3, with a sensitivity of 70% and a specificity of 69%. CONCLUSION Thiol/disulphide homeostasis may be used as a novel oxidative stress marker in patients with AMI because it is readily available, easily calculated, and relatively cheap. Further studies are needed to confirm the pathophysiologic role of thiol/disulphide homeostasis in AMI.

Oxidative stress and decreased thiol level in patients with migraine: cross-sectional study

Although migraine is a neurological disorder known since long, its physiopathology remains unclear. Recent studies suggest that migraine is associated with oxidative stress; however, they report divergent results. The aim of the present study was to evaluate total antioxidant status (TAS), total oxidant status (TOS), oxidative stress index (OSI), and serum thiol level in migraine patients with or without aura. The study group consisted of 141 migraine patients. The control group included 70 healthy subjects. TAS, TOS, OSI were evaluated using a method developed by Erel. Serum thiol level was measured using the Hu method. No difference was found in TAS, TOS, OSI between the patients and controls. The level of thiol was significantly lower in patients than in controls. Negative correlations were detected between thiol level and Migraine Disability Assessment score in patients. Although TAS, TOS, and OSI were similar to those of the control group, serum thiol level, an important marker of antioxidant capacity, was significantly lower in migraines compared with controls, and caused more serious disability. Novel treatment approaches may be developed based on these data, and compounds containing thiol, such as alpha lipoic acid and N-acetyl cysteine, may be used in prophylaxis.

Association of thiol/disulfide ratio with syntax score in patients with NSTEMI

Abstract Objective. The aim of this study was to investigate the relation between native thiol/disulfide ratio (TDR) and severity of coronary atherosclerosis as assessed by the Syntax score (SXscore) in patients with non-ST elevation myocardial infarction (NSTEMI) who underwent coronary angiography. Material and Methods. A total of 290 patients with NSTEMI who underwent coronary angiography, were included in the study between January and August 2014. Baseline coronary angiography determined the SXscore. The patients were divided into two groups: one with low SXscores (< 23) and the other with high SXscores (≥ 23). Results. TDR was significantly lower in patients with high SXscores (p < 0.001). In-hospital mortality was higher in the group with low TDR and high SXscores. The cut-off value of TDR on admission that predicted a high SXscore in the groups combined was 14, with a sensitivity of 73% and a specificity of 68%. Conclusion. TDR can be determined by an easy, inexpensive, automated, or optionally manual spectrophotometric assay, and correlates inversely with SXscore in patients with NSTEMI.

Dynamic thiol/disulphide homeostasis in patients with newly diagnosed primary hypertension

We aimed to investigate the thiol/disulphide homeostasis in patients with newly diagnosed primary hypertension with a novel and automated method. Blood thiol/disulphide homeostasis, which consists of native thiol/disulphide exchanges, was investigated in 45 patients with primary hypertension and 45 healthy controls. The levels of native thiol, total thiol, and native thiol/total thiol ratio were lower while the disulphide level and disulphide/native thiol and disulphide/total thiol ratios were higher in patients with primary hypertension when compared with those in the control group. Positive correlation was detected between 24-hour systolic and diastolic blood pressure levels and disulphide/native thiol ratio. With reference to the stepwise multiple linear regression model; increase in disulphide/native thiol ratio and log(24-hour urine microalbumin) and decrease in native thiol/total thiol ratio are independent predictors of 24-hour systolic and diastolic blood pressure. This study demonstrated that thiol/disulphide homeostasis was shifted toward disulphide formation in patients with primary hypertension.

Oxidative Stress and Anti-oxidative Defence in Patients with Age-related Macular Degeneration

Abstract Purpose: To evaluate the oxidative stress status and anti-oxidative defence in patients with age-related macular degeneration (AMD). Methods: A total of 22 patients diagnosed with AMD and 23 age-matched healthy controls were included in the present study. Serum levels of total oxidant status (TOS), total antioxidant status (TAS), total thiol status (TTS) and paraoxonase 1 (PON1) activity were investigated from samples. Results: Significant increase in TOS levels were observed in sera of AMD patients (25.3 ± 12.8) compared to controls (15.0 ± 4.4). TTS (404.3 ± 55.3) and serum PON1 enzyme activities (163.0 ± 65.5) were significantly lower in AMD patients (594.0 ± 64.2) relative to control groups (252.8 ± 132.7). Conclusion: The results of the present study show that there is a significant increase in oxidative stress in AMD patients and significant decrease in antioxidant defence, in the total thiol level and in PON1 activity in AMD patients compared with controls. The increased oxidative stress and decreased antioxidant levels may have a synergistic role in AMD development.

Maternal serum 25(OH)D levels in the third trimester of pregnancy during the winter season

Objective. To measure serum 25(OH)D levels of pregnant women in the last trimester during the winter season and to determine the factors affecting their serum levels. Methods. In all, 79 pregnant women in the third trimester were examined between November 2008 and March 2009. Serum calcium, phosphorus, alkaline phosphatase, parathyroid hormone, and 25(OH)D levels were measured. Maternal age, education, socioeconomic status (SES), nutrition, dressing habits, and level of sunlight exposure were determined and their correlation with serum 25(OH)D levels were statistically compared. Results. The mean serum 25(OH)D level of the study group was 11.95 ± 7.20 ng/ml, and the prevalence of severe vitamin D deficiency [25(OH)D < 10 ng/ml] in pregnant women was 45.6%. No association was detected between severe vitamin D deficiency and maternal age, gravidity, skin phototype, benefiting from ultraviolet index, and educational status of the cases. Also in patients who used multivitamin supplements and good SES, 25(OH)D levels were significantly higher (p = 0.046, p = 0.025, respectively). Conclusions. This study showed a remarkable high rate of vitamin D deficiency in pregnant women during the winter season and we have found high levels of vitamin D in patients supplemented with multivitamins and in ones with good SES.

Serum Thiol/Disulphide Homeostasis in Preeclampsia

Objective: To determine the serum thiol/disulphide homeostasis in preeclampsia and to investigate the association with clinical parameters. Methods: Forty-three pregnant women with preeclampsia and 43 healthy, uncomplicated pregnancies were included in the study. Native thiol, disulphide, and total thiol concentrations were measured by a novel automated method. Results: The serum native and total thiol levels were significantly lower in preeclampsia when compared with the healthy group (p < 0.001). There were significant correlations among the homeostatic parameters and preeclampsia. Conclusion: Serum thiol/disulphide homeostasis may have a role in the pathogenesis and can be evaluated with the clinical and laboratory findings of preeclampsia.

The relation of serum thiol levels and thiol/disulphide homeostasis with the severity of coronary artery disease

BACKGROUND The balance of oxidant and antioxidant status plays a key role in the coronary artery diseases (CAD). Thiol is one of the most important antioxidant barriers in humans, and thiol/disulphide homeostasis is a novel oxidative stress marker. AIM We aimed to investigate the relation of serum thiol levels and thiol/disulphide homeostasis with the presence and severity of CAD. METHODS A total of 161 patients who underwent coronary angiography owing to stable angina pectoris were consecutively enrolled. They were divided into three groups. Group I - 47 age- and gender-matched subjects with normal coronary angiography (control); group II - 71 newly diagnosed CAD patients with noncritical stenosis; and group III - 43 newly diagnosed CAD patients with critical stenosis. Serum native thiol, total thiol, and disulphide levels were measured, and disulphide/thiol ratios were calculated. Gensini scores were calculated in CAD patients. RESULTS While the highest thiol levels were found in group I, the lowest one was observed in group III (p < 0.001). Total and native thiol levels were significantly lower in group II than in group I (p < 0.001 for each), but they increased considerably in group II compared with group III (p = 0.031 and p = 0.028, respectively). Disulphide levels decreased in group II and III compared with group I (p < 0.001 for each). No statistically significant changes were observed in disulphide/thiol ratios (p > 0.05). Gensini scores were negatively correlated with total and native thiols, and positively with age and dyslipidaemia. Stepwise linear regression analyses showed that native thiol was an independent predictor in the final model for Gensini score. Receiver operating characteristic curve analysis demonstrated that thiol values of 310.7 or below could predict CAD with 89% sensitivity and 85% specificity (AUC = 0.918; 95% CI 0.870-0.965). CONCLUSIONS While the disulphide/thiol ratio did not change significantly, decreased native thiol levels were associated with the presence and severity of CAD. This result indicates that the reduction of thiols may be an important factor in the development of CAD.

The association of thiol/disulphide homeostasis and lipid accumulation index with cardiovascular risk factors in overweight adolescents with polycystic ovary syndrome

To assess thiol/disulphide homeostasis and lipid accumulation product index, and to determine whether they are associated with increased cardiovascular disease (CVD) risk or not in overweight adolescents with polycystic ovary syndrome (PCOS).