Glutamate Signaling Pathway in Absence Epilepsy: Possible Role of Ionotropic AMPA Glutamate Receptor Type 1 Subunit.

AMPA receptors, consisting of glutamate receptor type1 (GluR1) subunit are involved in the pathophysiology of some neurological disorders. In this study, the role of the GluR1 subunit in the development, as well as features of absence seizures were assessed. Both Wistar and WAG/Rij (a genetic animal model of absence epilepsy) rats with 2 and 6-month ages were included in the study. The expression of GluR1 was measured in the somatosensory cortex. Moreover, the effects of pharmacological activation and inhibition of AMPA receptors on the characteristic of absence epileptic activities were evaluated by microinjection of agonist or antagonist of AMPA receptors on the somatosensory cortex in the epileptic WAG/Rij rats. Distribution of the GluR1 subunit of AMPA receptors in the both IV (p < 0.001) and VI (p < 0.01) layers of the somatosensory cortex in the epileptic WAG/Rij rats was higher than non-epileptic animals. In addition, the microinjection of AMPA receptors agonist on the somatosensory cortex of the WAG/Rij rats increased both amplitude (p < 0.01) and duration (p < 0.001) of spike-wave discharges (SWDs), while injection of antagonist reduced amplitude (p < 0.001) and duration (p < 0.01) of SWDs in the somatosensory cortex of epileptic rats. The high expression of GluR1 in the somatosensory cortex of epileptic rats suggests the role of AMPA receptors consisting of the GluR1 subunit in the development of absence seizures. The modulatory effects AMPA receptors on the feature of SWDs suggest the potential of AMPA receptors antagonists as a therapeutic target for absence epilepsy.

Two-phase and three-phase liquid-phase microextraction of hydrochlorothiazide and triamterene in urine samples.

This paper reports the applicability of two-phase and three-phase hollow fiber based liquid-phase microextraction (HF-LPME) for the extraction of hydrochlorothiazide (HYD) and triamterene (TRM) from human urine. The HYD in two-phase HF-LPME is extracted from 24 mL of the aqueous sample into an organic phase with microliter volume located inside the pores and lumen of a polypropylene hollow fiber as acceptor phase, but the TRM in three-phase HF-LPME is extracted from aqueous donor phase to organic phase and then back-extracted to the aqueous acceptor phase, which can be directly injected into HPLC for analysis. Under optimized conditions preconcentration factors of HYD and TRM were obtained as 128 and 239, respectively. The calibration curves were linear (R(2) ≥ 0.995) in the concentration range of 1.0-100 µg/L for HYD and 2.0-100 µg/L for TRM. The limits of detection for HYD and TRM were 0.5 µg/L. The intra-day and inter-day RSD based on four replicates were obtained as ≤5.8 and ≤9.3%, respectively. The methods were successfully applied for determining the concentration of the drugs in urine samples. Copyright © 2015 John Wiley & Sons, Ltd.

Hollow-fiber-supported liquid membrane microextraction of amlodipine and atorvastatin.

A simple, environmentally friendly, and efficient method, based on hollow-fiber-supported liquid membrane microextraction, followed by high-performance liquid chromatography has been developed for the extraction and determination of amlodipine (AML) and atorvastatin (ATO) in water and urine samples. The AML in two-phase hollow-fiber liquid microextraction is extracted from 24.0 mL of the aqueous sample into an organic phase with microliter volume located inside the pores and lumen of a polypropylene hollow fiber as acceptor phase, but the ATO in three-phase hollow-fiber liquid microextraction is extracted from aqueous donor phase to organic phase and then back-extracted to the aqueous acceptor phase, which can be directly injected into the high-performance liquid chromatograph for analysis. The preconcentration factors in a range of 34-135 were obtained under the optimum conditions. The calibration curves were linear (R(2) ≥ 0.990) in the concentration range of 2.0-200 µg/L for AML and 5.0-200 µg/L for ATO. The limits of detection for AML and ATO were 0.5 and 2.0 µg/L, respectively. Tap water and human urine samples were successfully analyzed for the existence of AML and ATO using the proposed methods.