European Journal of Obstetrics & Gynecology and Reproductive Biology
Measurement of the total antioxidant response in preeclampsia with a novel automated method
Introduction
Reactive oxygen species (ROS) are produced during many metabolic and physiological processes. All organisms possess a range of enzymatic and non-enzymatic antioxidant systems which serve to protect them against the harmful oxidative reactions that occur as a consequence of this endogenous ROS production. Under certain conditions, increases in oxidants and decreases in antioxidants cannot be prevented, and the oxidant/antioxidant balance shifts towards the oxidative state. Consequently, oxidative stress, which has been implicated in over a hundred disorders, including preeclampsia, develops [1].
There is increasing evidence that oxidative stress is an important contributing factor in the pathogenesis of preeclampsia. Lipid peroxidation has been implicated in the vascular dysfunction that underlies this disorder, and a number of studies have reported increased serum levels of lipid peroxidation products together with a reduction in the levels of the serum antioxidant components [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12]. Antioxidant supplementation in women at risk of preeclampsia has been associated with an improvement in biochemical indices of the disease, and supplementation with antioxidants may have a beneficial effect in the prevention of this condition [13], [14].
Knowledge of the total responses of the serum antioxidant systems in pre-eclampsia is limited [12]. Radical-scavenging antioxidants are consumed by the increased free radical activity associated with this condition, and the total antioxidant status has been used to indirectly assess free-radical activity [10], [11], [15]. There are conflicting results concerning this topic. Kharb [10], [11] found significantly higher TARs in women with preeclampsia, while Shaarawy et al. [12] found significantly lower TAR values in preeclamptic patients than had been reported in other studies.
Various methods have been developed for the measurement of total antioxidant status. However, there is not yet an accepted “gold standard” reference method [2], and decisions concerning standardisation, and the terms and units used for the measurement of TAR have not yet been made [16]. This implies that this topic needs to be studied further [17]. The most widely used methods for TAR measurement are colorimetric, or involve either fluorescence or chemiluminescence [18], [19], [20]. The fluorescence and chemiluminescence methods require sophisticated techniques, and these improved systems are not present in many routine clinical biochemistry laboratories. On the other hand, even when these techologies are available, their routine use is limited [16].
In this study, we aimed to measure both the levels of individual antioxidant components and the TAR values in plasma samples from pregnant women to evaluate their antioxidant status using a novel automated method [17]. As a reciprocal measure, the total peroxide levels of the same plasma samples were also measured. The percent ratio of the total plasma peroxide level to the plasma TAR level was regarded as the oxidative stress index (OSI) [21].
Section snippets
Subjects
The study population, treated in our department, consisted of 24 women with preeclampsia and 18 women with normal, normotensive pregnancies. The diagnosis of preeclampsia was established in accordance with the American College of Obstetrics and Gynecology definition [22]. All women gave informed consent to participate in the study, which had been approved by the local Ethics Committee. None of the patients had pre-existing hypertensive disorders or any renal, hepatic, or hematologic diseases,
Results
The demographic and clinical data of the subjects are shown in Table 1. As expected, the women affected by preeclampsia demonstrated significantly higher systolic (P<0.001) and diastolic blood pressures (P<0.001) than women with normal pregnancies. Furthermore, the women with preeclampsia had a significantly higher mean body weight (P<0.001) and gave birth to babies with significantly lower birth weights (P<0.001). The maternal age, gestational age, gravidity, parity, and placental weight also
Comment
It is well known that oxidative stress increases during normal pregnancy. In healthy pregnancy it has been reported that plasma lipid hydroperoxide levels are increased, and the total antioxidant capacity decreased [26], while the activity of the antioxidant enzyme erythrocyte glutathione peroxidase is decreased, along with the levels of its cofactor selenium [4]. However, the nature of this mechanism is not yet known.
Preeclampsia remains one of the most serious complications of pregnancy. The
References (27)
Free radicals, antioxidants, and human disease: curiosity, cause, or consequence
Lancet
(1994)- et al.
Increased ascorbate radical formation and ascorbate depletion in plasma from women with preeclampsia: implications for oxidative stress
Free Radic. Biol. Med
(1997) - et al.
The changes of trace elements, malondialdehyde levels and superoxide dismutase activities in pregnancy with or without preeclampsia
Clin. Biochem
(2002) - et al.
Invasive cytotrophoblasts manifest evidence of oxidative stress in preeclampsia
Am. J. Pathol
(2000) - et al.
C in preeclampsia
Eur. J. Obstet. Gynecol. Reprod. Biol
(2000) Total free radical trapping antioxidant potential in pre-eclampsia
Int. J. Gynaecol. Obstet
(2000)- et al.
Radical-scavenging antioxidants in pre-eclampsia and eclampsia
Int. J. Gynecol. Obstet
(1998) - et al.
Preeclampsia and antioxidant nutrients: decreased plasma levels of reduced ascorbic acid, alpha-tocopherol, and beta-carotene in women with preeclampsia
Am. J. Obstet. Gynecol
(1994) - et al.
Effect of antioxidants on the occurrence of pre-eclampsia in women at increased risk: a randomised trial
Lancet
(1999) - et al.
The relative contributions of vitamin E, urate, ascorbate and proteins to the total peroxyl radical-trapping antioxidant activity of human blood plasma
Biochim. Biophys. Acta
(1987)