Evaluation of dynamic thiol-disulfide homeostasis in very low-birth-weighted preterms

Evaluation of thiol-disulfide homeostasis and oxidative stress parameters in newborns receiving phototherapy

The aim of our study was to evaluate oxidative stress and thiol-disulfide homeostasis in term newborns receiving phototherapy. The study was planned as a single-blind, intervention study in a single center with level 3 neonatal intensive care unit to investigate the effect of phototherapy on the oxidative system in term newborns with hyperbilirubinemia. Neonates with hyperbilirubinemia were treated with total body exposure phototherapy technique for 18 h using a Novos^® device. Blood samples of 28 term newborns were taken before and after phototherapy. Total and native thiol, total antioxidant status (TAS) and total oxidant status (TOS), and oxidative stress index (OSI) levels were measured. The 28 newborn patients included 15 (54%) males and 13 (46%) females with a mean birthweight of 3080.1 ± 366.5 g. Native and total thiol levels were found to be decreased in patients receiving phototherapy (p = 0.021, p = 0.010). Besides, significantly lower TAS and TOS levels were found after phototherapy (p < 0.001, p < 0.001). We found that decreased thiol levels were related to increased oxidative stress. We also determined significantly the lower bilirubin levels after phototherapy (p < 0.001). In conclusion, we found that phototherapy treatment induced decreased oxidative stress associated with hyperbilirubinemia in neonates. Thiol-disulfide homeostasis can be used as a marker of oxidative stress due to hyperbilirubinemia in the early period.

The evaluation of maternal systemic thiol/disulphide homeostasis for the short-term prediction of preterm birth in women with threatened preterm labour: a pilot study

The aim of this study was to investigate maternal systemic thiol/disulphide homeostasis (TDH) for the short-term prediction of preterm birth in women with threatened preterm labour (TPL). This prospective study included 75 pregnant women whose pregnancies were complicated by TPL. Thirty-seven of them delivered within 7 days and 38 of them delivered beyond 7 days. Maternal serum samples were collected at the day of diagnosis and the TDH was measured. The maternal disulphide level was significantly higher in pregnant women who delivered within 7 days (25.0 ± 9.8 μmol/L vs 19.4 ± 9.8 μmol/L, p: .015). The threshold value of 22.1 μmol/L for maternal disulphide level predicted delivery within 7 days with 62.2% sensitivity and 60.5% specificity (area under curve 0.651, confidence interval 0.53-0.78). The likelihood ratios for short cervix (≤25 mm) and maternal disulphide level (≥22 μmol/L) to predict delivery within 7 days was found to be 8.7 and 7.3, respectively. The likelihood ratio of combining two tests to predict delivery within 7 days was found to be 11.4. The maternal TDH, which is an indicator of oxidative stress status in maternal compartment, is disturbed in TPL cases who delivered within 7 days. Elevated maternal disulphide level along with cervical length screening predicts a short latency period in pregnancies with TPL. IMPACT STATEMENTWhat is already known on this subject? Spontaneous preterm delivery is one of the major complication of pregnancy and the common cause of neonatal morbidity and mortality. Threatened preterm labour (TPL) is also a frequent complaint in obstetric emergency care units in all around the world. Triaging women with TPL is mandatory for planning further management therapies, since the most of them will eventually deliver at term. Only the measurement of cervical length in symptomatic women has moderate accuracy in predicting preterm delivery. Short cervix is described as an independent predictor of preterm delivery in women with TPL, its predictive accuracy as a single measurement is relatively limited. On this account, several potential markers like foetal fibronectin in the cervicovaginal fluid, salivary oestriol, prolactin in vaginal discharge, maternal serum calponin and interleukin-6 in the amniotic fluid were examined to predict preterm delivery in previous studies. However, none of them represented an excessive predictive accuracy like high sensitivity, PPV or NPV.What do the results of this study add? We report a method which has higher diagnostic and predictive performance to identifying TPL women with high risk of preterm delivery. According to the current literature, there are accumulated data about the correlation between oxidative stress (OS) and preterm delivery regardless of the amniotic membrane status. However, it is still debated whether OS is a trigger or a consequence of preterm delivery. Our study provides evidence for the first time that maternal serum thiol/disulphide homeostasis, which is an indicator of OS in maternal compartment, is disturbed in TPL cases who delivered within 7 days. The high disulphide level in maternal serum, along with cervical length measurement (short cervix) accurately predicts a short latency period in TPL cases.What are the implications of these findings for clinical practice and/or further research? This novel test combination (maternal serum disulphide level and cervical length measurement) could be used clinically to triage pregnant women presenting with TPL, avoiding overtreatment, unnecessary hospitalisations and increased medical costs. The future research would be addressed on reducing maternal OS by using new antioxidant treatment strategies to improve perinatal and long-term childhood outcomes.

Evaluation of Fetal Serum Thiol/Disulfide Homeostasis and Ischemia-Modified Albumin Levels in Fetal Distress

Aim: We investigated the association of fetal serum thiol/disulfide homeostasis and ischemia-modified albumin (IMA) levels with fetal distress (FD). Methods: Umbilical cord blood for native thiol, total thiol, disulfide, albumin, and IMA analysis was obtained from 44 pregnant women over 34 weeks gestation undergoing cesarean section due to non-acute FD, and from 61 healthy pregnant women who underwent elective cesarean section Results: Native thiol and total thiol levels were significantly lower in the FD group (p = 0.02 and p = 0.014, respectively). Although disulfide/native thiol and disulfide/total thiol ratios were higher in the FD group, the difference was statistically insignificant (p = 0.805). The IMA levels were significantly higher in the FD group (p = 0.013). Conclusion: The thiol-disulfide homeostasis shifts toward the oxidant direction during the FD pathogenesis and the increased IMA levels may be the best indicator of an underlying non-acute ischemic condition.

Thiol-disulfide homeostasis: an integrated approach with biochemical and clinical aspects

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, nonsmall cell lung cancer, familial Mediterranean fever (FMF), 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.

The relationship between oxidative stress and preeclampsia. The serum ischemia-modified albumin levels and thiol/disulfide homeostasis

Objective

Preeclampsia (PE) is a dangerous complication of pregnancy and still a major cause of maternal-fetal morbidity and mortality. Its etiology remains largely unknown, but researchers have suggested oxidative stress-mediated inflammation for the same. The purpose of this study is to investigate the relationship between oxidative stress and PE as well as the usability of oxidative stress indicators such as serum ischemia-modified albumin (IMA) levels and thiol/disulfide balance in the prediction of PE.

Materials and Methods

The study included 47 pregnant women with PE and 57 healthy pregnant women. We measured their serum IMA, native thiol, total thiol, and disulfide levels. Additionally, we determined the optimal cutoff values via the receiver operating characteristic curve analysis.

Results

There were no differences between the two groups with respect to the maternal age, body mass index, gravida, and parity. The native and total thiol levels were found to be low when the disulfide and IMA levels were high in the patients with PE (p<0.05). When the IMA level was corrected by the albumin level (IMAR), the significant difference between the two groups disappeared. We also found that the native and total thiol concentrations were correlated with the systolic and diastolic blood pressures. The optimal cut-off values calculated for the prediction of PE were as follows: 178.45 µmol/L (with sensitivity of 72% and specificity of 83%) for native thiol, 232.55 µ mol/L (with a sensitivity of 75% and specificity of 85%) for total thiol, and 29.05 µmol/L (with sensitivity of 65% and specificity of 72%) for disulfide.

Conclusion

The balance of thiol/disulfide may play a role in the pathogenesis of PE and could be used as a biological marker for PE.

The role of thiol-disulfide homeostasis in neonatal sepsis

BACKGROUND AND AIM

The thiol-disulfide homeostasis is essential for the body to maintain effective antioxidant defense mechanisms. We aimed to show the relationship between sepsis and thiol-disulfide homeostasis in newborns.

MATERIALS AND METHODS

In this prospective study, 66 newborns with sepsis (group 1) and 51 healthy controls (group 2) were included. In group 1, 53 newborns were diagnosed as clinical sepsis (group 1a) and 13 as definite sepsis (group 1b). The study has two time points; the day of diagnosis (step 1) and three days after the treatment (step 2). At step 1, group 1 and group 2 were compared for thiol-disulfide homeostasis as well as inflammatory markers. At step 2, the same laboratory tests were repeated only in group 1.

RESULTS

At step 1, the levels of C-reactive protein (CRP) and interleukin-6 (IL-6) were higher, while native thiol and total thiol levels were lower in group 1 compared to controls. Serum disulfide/total thiol ratio was also significantly higher in group 1. When analyzed for subgroups of group 1, demonstration of microorganism did not affect the serum thiol levels. Within group 1, at step 2, although CRP and IL-6 levels were significantly lowered compared to step 1, we did not observe significant changes in thiol-disulfide parameters.

CONCLUSIONS

The thiol-disulfide homeostasis may have a role in the pathogenesis of sepsis in newborns. The related parameters might be new markers for the diagnosis of sepsis in newborn patients. Further studies are needed to define the role of thiol-disulfide homeostasis in the course of neonatal sepsis.