Simultaneous Determination of 10 Kinds of Cyanotoxins in Lake Water by Solid Phase Extraction-High Performance Liquid Chromatography Coupled with Photodiode Array Detector / 分析化学

A method has been developed by solid phase extraction-high performance liquid chromatography coupled with photodiode array detector for simultaneous determination of 10 kinds of cyanotoxins in lake water, including microcystin-RR (MC-RR), MC-YR, MC-HtyR, MC-LR, MC-WR, MC-LA, MC-LY, MC-LW, MC-LF and nodularin ( NOD ).The samples were enriched and purified by a HLB solid phase extraction column.The separation was performed on a Waters C18 column (250 mm×4.6 mm, 5 μm) with the gradient elution of acetonitrile and water containing 0.05% trifluoroacetic acid.The flow rate of the mobile phase was 0.8 mL/min.The column temperature was 30℃ and the injection volume was 20 μL.The photodiode array detector was scanned from 190 nm to 300 nm and the detection wavelength was 238 nm.Multiple qualitative analyses were completed according to retention time, full scanning spectrum of photodiode array detector and purity analysis of chromatographic peak.Good linearity was observed in the cyanotoxin concentration range of 0.05 mg/L-2.0 mg/L with correlation coefficients ( R) from 0.9998 to 0.9999.The limits of detection for 10 cyanotoxins were in the range of 0.005 μg/L-0.020 μg/L.The recoveries were in the range of 85.1%-105.3% at the three spiked levels of 0.1 mg/L, 1.0 mg/L and 1.8 mg/L with the relative standard deviations ( RSD ) of 0.8% -9.2%.The method was characteriZed by wide applicability, convenient operation, quick analytical rate, high sensitivity, good accuracy and high recovery.The qualitative accuracy was improved by using multiple qualitative analyses.This method was successfully applied to determination of 10 kinds of cyanotoxins in lake water.

Protection of hepatocyte growth factor on neurons subjected to oxygen-glucose deprivation/reperfusion / 生理学报

The present study was conducted to investigate the effect of hepatocyte growth factor (HGF) on cortical neurons exposed to oxygen-glucose deprivation/reperfusion (OGD/R). Primary cultured cerebral cortical neurons were prepared from Sprague-Dawley rats. The cells were used for experiments after culture for 12 d in vitro. To initiate OGD/R, the culture medium was replaced by glucose-free medium, and cells were transferred to a humidified incubation chamber flushed by a gas mixture of 95% N(2) and 5% CO(2) at 37 °C for 2 h. Following this treatment, neurons were fed with glucose-supplemented (25 mmol/L) medium, and returned to the incubator under normoxic condition for 0-24 h. The cell viability was assessed by MTT assay, and cell injury was evaluated by lactate dehydrogenase (LDH) leakage rate. The percentage of apoptotic cells was analyzed by flow cytometry and Hoechst 33258 staining. The expressions of c-Met mRNA and protein were detected by RT-PCR and Western blot analysis, respectively. Oxygen-glucose deprivation for 2 h decreased the cell viability and increased LDH leakage rate in cultured cerebral cortical neurons. The cell viability declined and LDH leakage rate increased with the reperfusion time going on (0-24 h). To explore the influence of HGF on neurons under oxygen-glucose deprivation for 2 h/reperfusion for 24 h (OGD(2)/R(24)) condition, the cultures were pretreated with HGF at different concentrations (5-120 ng/mL) 2 h prior to OGD(2)/R(24). The results showed that OGD(2)/R(24) treatment significantly decreased the cell viability, increased LDH leakage rate and the percentage of apopototic cells. Pretreatment with HGF at 5 ng/mL and 10 ng/mL did not affect the decrease in cell viability resulting from OGD(2)/R(24). In the presence of 20 ng/mL HGF, the increase in cell viability in cortical neurons exposed to OGD(2)/R(24) began to appear, and 80 ng/mL of HGF exhibited the maximal effect. HGF at 5, 10 and 20 ng/mL did not affect the increase in LDH leakage rate in cortical neurons exposed to OGD(2)/R(24). In the presence of 40 ng/mL HGF, the decrease in LDH leakage rate in cortical neurons subjected to OGD(2)/R(24) began to appear, and 80 ng/mL of HGF displayed the maximal effect. In addition, HGF at 80 ng/mL significantly attenuated cell apoptosis resulting from OGD(2)/R(24). As detected by semi-quantitative RT-PCR and Western blot analysis, c-Met mRNA and protein were expressed in cerebral cortical neurons cultured for 12 d in vitro. c-Met mRNA and protein expressions in cortical neurons exposed to OGD(2)/R(24) were significantly upregulated and were not affected by pretreatment of HGF at 80 ng/mL. Treatment with c-Met inhibitor SU11274 (5 μmol/L) completely eliminated HGF-mediated protection of cortical neurons subjected to OGD(2)/R(24). The results suggest that HGF directly protects cortical neurons against OGD/R-induced cell injury in a dose-dependent manner, and HGF has a potent anti-apoptotic action on neurons exposed to OGD/R.

Effects of hypoxic preconditioning on hypoxia tolerance of astrocytes in vitro / 中国应用生理学杂志

<p><b>AIM</b>To explore the mechanisms of hypoxic preconditioning on protecting cultured astrocytes from hypoxia injury.</p><p><b>METHODS</b>Cultured astrocytes were divided randomly into several groups: control(C), hypoxia(H) and hypoxic preconditioning (HP). Cells MTT metabolic activity, qualitation of apoptosis and modality to explore the protection effects of hypoxic preconditioning. Immunocytochemistry of Bcl-2 and Bax to explore the mechanisms of hypoxic preconditioning on protecting astrocytes from hypoxia.</p><p><b>RESULTS</b>Compared with H group there was marked increase of MTT metabolic activity in HP48 and HP72 groups. Immunocytochemistry of Bcl-2 and Bax showed that compared with H group, expression of Bcl-2 was increased in HP group, while expression of Bax was decreased in HP group.</p><p><b>CONCLUSION</b>Hypoxic preconditioning can protect astrocytes from hypoxia. One possible mechanism maybe concerned with inhibition of Bax and maintain of Bcl-2 to depress apoptosis procedure.</p>