Research Progress on Chiral Separation Methods and Toxic Effects of Methamphetamine Enantiomers / 法医学杂志

Methamphetamine （MAMP） is a kind of amphetamine-type stimulants （ATS） which contains one chiral carbon atom in its structure. Therefore a pair of enantiomers, S-（+）-MAMP and R-（-）-MAMP exist. R type and S type methamphetamines possess similar physicochemical properties, but has largely different pharmacological and toxic effects. S-（+）-MAMP is the main component of addictive drug "Ice" at present, seriously affecting human health and public safety. The separation analysis and mechanism of toxic effects discussions on MAMP are the current research focuses. This paper reviews the research progress of separation analysis methods and toxic effects of methamphetamine enantiomers to provide reference for forensic study and forensic practice.

Quantitative determination of podophyllotoxin in dermal and blood microdialysis samples of rats by liquid chromatography-tandem mass spectrometry / 南方医科大学学报

<p><b>OBJECTIVE</b>To develop and validate a sensitive method for quantitative analysis of podophyllotoxin in blood and dermal microdialysis samples of rats based on liquid chromatography-tandem mass spectrometry (UFLC-MS-MS).</p><p><b>METHODS</b>The microdialysis samples were prepared by liquid-liquid extraction using ethyl acetate with etoposide as the internal standard (IS). Podophyllotoxin was separated with an Agilent ZORBAX XDB-C18 column (2.1 mmx50 mm, 3.5 microm). The mobile phase consisted of acetonitrile: 10 mmol/L ammonium acetate (40:60, V/V) at a flow rate of 0.3 ml/min and the analysis was performed at the ambient temperature. The UFLC-MS/MS system was operated in the mode of multiple reaction monitoring using the electrospray ionization technique in positive mode.</p><p><b>RESULTS</b>Podophyllotoxin and etoposide responses were optimized at the transitions m/z 432.7-->397.3 and 589.5-->229.5, respectively. Calibration curves were linear over the range 2.0-1000 ng/ml. The lowest limits of quantification and detection values were 2.0 ng/ml and 0.7 ng/ml, respectively. The inter- and intra-day precision and accuracy were both less than 15%.</p><p><b>CONCLUSION</b>This selective and sensitive method can be used to quantity podophyllotoxin in the blood and dermal microdialysates of rats.</p>

Pharmacokinetic study of polydatin in Beagle dogs / 南方医科大学学报

<p><b>OBJECTIVE</b>To establish a method for detecting plasma polydatin using high-performance liquid chromatography (HPLC) and investigate the pharmacokinetics of polydatin in Beagle dogs.</p><p><b>METHODS</b>HPLC-based detection of polydatin was performed on a Hypersil-BDS C18 column with a mobile phase of methanol and water (35:65) at the flow rate of 1.0 ml/min and the detection wavelength of 290 nm. The pharmacokinetic parameters of polydatin were calculated by non-compartment model statistics.</p><p><b>RESULTS</b>The standard curve was linear within the range of 0.21-21.0 microg/ml (correlation coefficient of 0.9995, n=5). The average recovery was 90% with a relative standard deviation no more than 8.0%. The limit of detection of the method was 0.1 microg/ml. The pharmacokinetic parameters of polydatin at 3 doses were obtained, with T((1/2)); of 89.95-/+19.96 min, 152.15-/+55.82 min, and 202.36-/+66.75 min, and AUC0-infinity of 300.14-/+51.33 g.min.ml(-1), 751.72-/+173.97 g.min.ml(-1) and 1521.12-/+310.02 microg.min.ml(-1), respectively.</p><p><b>CONCLUSION</b>The method we established allows effective detection of polydatin, whose pharmacokinetics conforms to the two-compartment model.</p>

Rapid identification of 22 abused drugs and organophosphorus pesticides in blood by LC-MS/MS / 南方医科大学学报

<p><b>OBJECTIVE</b>To develop a method for rapid identification of 22 abused drugs and organophosphorus pesticides in the blood.</p><p><b>METHODS</b>Liquid chromatography-tandem mass spectrometry (LC-MS/MS) in multiple-reaction monitoring mode (MRM) was employed for detecting the drugs and pesticides in the blood. The MRM database and criteria for identification were established, and ethyl acetate was used for extraction of the drugs. After 3 rounds of extractions of the blood sample (1 mL) using 2 mL ethyl acetate, the extract was vortexed for 3 min and centrifuged at 5000 r/min. Each organic phase was combined and evaporated by gentle N2 gas. The residue was re-dissolved in 100 L mobile phase, from which 5 L was taken for LC-MS/MS detection.</p><p><b>RESULTS</b>The detection of the 22 target compounds could be completed within 10 min. The limit of detection of the target compound ranged from 0.03 to 6.00 ng/ml. Satisfactory results were obtained in proficiency testing program organized by China National Accreditation Service for Conformity Assessment.</p><p><b>CONCLUSION</b>The method we established is rapid, selective and sensitive for detecting the 22 abused drugs and organophosphorus pesticides.</p>

High-performance liquid chromatography-electrospray ionization/tandem mass spectrometry of isofraxidin in Sarcandra glabra / 南方医科大学学报

<p><b>OBJECTIVE</b>To establish a method for determining isofraxidin concentrations in Sarcandra glabra and Qingrexiaoyanning capsules with high-performance liquid chromatographic-mass spectrometry.</p><p><b>METHODS</b>Isofraxidin was extracted from Sarcandra glabra and Qingrexiaoyanning capsules with acetic ether and chloroform, respectively, and separated by isocratic reversed-phase chromatography. The mass spectrometric system was operated in multiple reaction monitoring mode. A pair of ions: precursor ion m/z 223 with product ion m/z 162 were chosen for the quantification of the analyte.</p><p><b>RESULTS</b>The retention time of isofraxidin was 6.60 min, and the calibration curve was linear over a concentration range from 484 to 9 680 ng/ml. The average recovery was 96.7% and RSD 4.49%, with detection limit of 1 ng/ml.</p><p><b>CONCLUSION</b>The method is rapid, selective and sensitive for determining isofraxidin in Sarcandra glabra and Qingrexiaoyanning capsules.</p>

As2O3-induced permeability transition pore opening in mitochondria depends on Ca2+ / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore the mechanism of arsenite-induced permeability transition pore (PTP) opening and the role of Ca(2+). in As(2)O(3)-induced PTP opening.</p><p><b>METHOD</b>The mitochondria were prepared from Wistar rat liver and mitochondrial swelling was assessed spectrophotometrically at 540 nm to evaluate PTP opening. The membrane potential of the mitochondria was measured with fluorescence spectrophotometry.</p><p><b>RESULTS</b>PTP opening was induced with 10 micromol/L As(2)O(3) in the presence of 10 micromol/L Ca(2+), and the absorbance at 540 nm of the mitochondria did not decrease in response to exclusive treatment with 10 micromol/L As(2)O(3), or to 10 micromol/L As(2)O(3) plus 10 micromol/L Ca(2+) treatment with 0.5 mmol/L EGTA pretreatment. Treatment with As(2)O(3) at 0, 5, 10 and 20 micromol/L in the presence of 50, 20, 10 and 5 micromol/L Ca(2+), respectively, resulted in decreased absorbance at 540 nm of the mitochondria.</p><p><b>CONCLUSION</b>Ca(2+) mediates As(2)O(3)-induced PTP opening. As(2)O(3) lowers Ca(2+) threshold necessary for eliciting PTP opening and thereby regulates cell apoptosis.</p>

Detection and typing of dengue virus using polymerase chain reaction and microwell plate hybridization / 南方医科大学学报

<p><b>OBJECTIVE</b>To establish a specific, sensitive and practicable method for detection and typing of dengue virus.</p><p><b>METHODS</b>Based on the genomic sequence analysis of dengue virus types 1-4, 4 pairs of primers were designed. The specific capture probes of dengue virus types 1-4 were amplified using RT-PCR, cloned and sequenced before using them for precoating the microwell plate. The samples were amplified using biotin-labeled forward primer and reverse primer, and microwell plate hybridization was carried out for detection and typing of dengue virus types 1-4.</p><p><b>RESULTS</b>The absorbance of the positive samples were higher than 0.5, while the average absorbance of the negative samples was lower than 0.1, with the S/N higher than 10.</p><p><b>CONCLUSION</b>The method of PCR-ELISA we established for early detection and typing of all 4 dengue viruses seretypes.</p>

Resveratrol induces HepG2 cell apoptosis by depolarizing mitochondrial membrane / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effects of resveratrol on the proliferation, apoptosis, mitochondrial membrane potential and cell morphology of human liver cancer cell line HepG2.</p><p><b>METHODS</b>The changes in HepG2 cell growth and proliferation in response to resveratrol treatment were evaluated by MTT assay, and resveratrol-induced apoptosis of HepG2 cells was investigated by flow cytometry. Inverted microscope and electron microscope were employed for observing morphological changes of the treated cells. The whole-cell mitochondrial membrane potential was measured in separate experiments using two fluorimetric probes, rhodamine123 and TMRE, respectively. HepG2 cells treated with rhodamine123 were analyzed by flow cytometry and cells treated with TMRE by confocal microscope.</p><p><b>RESULTS</b>MTT assay showed that low concentrations of resveratrol produced no significant effect on the growth of HepG2 cells, whereas at high concentrations, resveratrol could obviously inhibit the cell growth in a time- and dose-dependent manner. Resveratrol also induced apoptosis of HepG2 cells, and after a 24-hour treatment, resveratrol caused sharp increment of the mitochondria membrane potential.</p><p><b>CONCLUSION</b>Resveratrol is capable of inhibiting the proliferation of HepG2 cells and inducing cell apoptosis by depolarizing mitochondrial membrane potential.</p>

Purification of a new phospholipase A2 homologue from Agkistrodon blomhoffii siniticus and its effects on gene expression profile of Hep3B cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To isolate and purify a new phospholipase A2 (PLA2) homologue from Agkistrodon blomhoffii siniticus and investigate its effects on the gene expression profile of Hep3B cells.</p><p><b>METHODS</b>The PLA2 homologue was isolated and purified by reverse-phase high-performance liquid chromatography (HPLC) and its purity was determined also by HPLC. The relative molecular mass of the homologue was measured by electrospray ionization mass spectrum. The gene expression profile of Hep3B cells was detected with gene chip after exposure of the cells to 139 microg/ml PLA2 homologue for 12 h.</p><p><b>RESULTS</b>The purity of the PLA2 homologue was 97.2%, whose relative molecular mass was 13,900. After exposure of Hep3B cells to 139 microg/ml PLA2 homologue for 12 h, 19 genes were down-regulated and 20 up-regulated in the cells. The genes showing altered expressions in response to the exposure were mainly involved in cell cycle control and DNA damage repair, cell apoptosis and senescence, production of signal transduction molecules and transcription factors, cell adhesion, angiogenesis, and tumor invasion and metastasis.</p><p><b>CONCLUSIONS</b>The PLA2 homologue induces alterations in the expression of a wide variety of genes involved in the growth and metastasis of tumor cells. The results of this study provide clues for further study of the possible mechanism for the action of PLA2 homologue on Hep3B cells.</p>