Abstract

Currently the field of epilepsy lacks peripheral blood-based biomarkers that could predict the onset or progression of chronic seizures following an epileptogenic injury. Thiol/disulfide ratios have been shown to provide a sensitive means of assessing the systemic redox potential in tissue and plasma. In this study, we utilized a rapid, simple and reliable method for simultaneous determination of several thiol-containing amino acids in plasma using HPLC with electrochemical detection in kainic acid (KA) and pilocarpine rat models of epilepsy. In contrast to GSH and GSSG levels, the levels of cysteine (Cys) were decreased by 42% and 62% and cystine (Cyss) were increased by 46% and 23% in the plasma of KA- and pilocarpine-injected rats, respectively after 48 h. In chronically epileptic rats, plasma cysteine was decreased by 40.4% and 37.7%, and plasma GSSG increased by 33.8% and 35.0% following KA and pilocarpine, respectively. Treatment of rats with a catalytic antioxidant, 60 min after KA or pilocarpine significant attenuated the decrease of plasma Cys/Cyss ratios at the 48 h time point in both models. These observations suggest that the decreased cysteine and ratio of Cys/Cyss in plasma could potentially serve as redox biomarkers in temporal lobe epilepsy.

Abstract

The determination of 4-nonylphenols has been developed using HPLC with fluorescence detection method. 4-Nonylphenols in sea water samples were extracted using a liquid–liquid extraction. Acidification and adding salting-out agents (NaI) of water samples increased the extraction degree. The extraction of 4-nonylphenols was done twice with 20 mL of methylene chloride. The applied concentrated range was over 5–1000 ng/mL for the 4-nonylphenol. The recovery test ranged from 78.5 to 89.9% with relative standard deviations between 1.0 and 7.5% of 100 ng/mL of the standard phenols spiked with the water sample and the detection limit was 1 ng/mL. The proposed method was applied satisfactorily for the determination of 4-nonylphenole in sea water samples. Levels of 4-nonylphenol were determined in the sea waters of the Amur Bay. Water samples were collected every year from 2008 to 2015. Concentrations of 4-nonylphenol in the waters ranged from levels below the detection limits up to 1.24 μg/L.