Yantong Sun

Simultaneous quantitation of hydrochlorothiazide and metoprolol in human plasma by liquid chromatography-tandem mass spectrometry.

A rapid and sensitive method for the simultaneous quantitation of hydrochlorothiazide (HCT) and metoprolol (MET) in human plasma based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed and validated. MS/MS detection involved switching the electrospray ionization (ESI) mode during chromatography from negative to detect HCT and its internal standard (I.S.) 5-bromouracil to positive to detect MET and its I.S. tramadol. Sample preparation by liquid-liquid extraction with diethyl ether-dichloromethane (60:40, v/v) was followed by chromatography on a Venusil MP-C18 column using methanol-ammonium acetate (10mM)-formic acid (pH 3.4) (50:50:0.05, v/v/v) at a flow rate of 0.8mL/min. The method was linear in the concentration range 3-1000ng/mL for both HCT and MET using 100microL human plasma. Intra- and inter-day precisions (as relative standard deviation) for HCT were 2.9-3.9% and 3.9-4.7%, respectively and for MET were 2.4-4.1% and 4.7-6.2%, respectively. Accuracies (as relative error) were +/-3.8% and +/-2.6% for HCT and MET, respectively. The assay was successfully applied to a pharmacokinetic study involving a single oral dose of a combination tablet (25mg HCT, 50mg MET) in healthy volunteers.

A liquid chromatography–tandem mass spectrometry method for the simultaneous quantification of escin Ia and escin Ib in human plasma: application to a pharmacokinetic study after intravenous administration

A rapid and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for simultaneous quantification of escin Ia and escin Ib in human plasma. After a solid-phase extraction (SPE), the analytes were separated on a Zorbax Extend C(18) column by isocratic elution with a mobile phase of methanol-acetonitrile-10 mm ammonium acetate (27:27:46, v/v/v) at a flow rate of 1.0 mL/min and analyzed by mass spectrometry in the positive ion multiple reaction monitoring mode. The precursor to product ion transitions of m/z 1131.8 → 807.6 was used to quantify escin Ia and escin Ib. Good linearity was achieved over a wide range of 2.00-900 ng/mL for escin Ia and 1.50-662 ng/mL for escin Ib. The intra- and inter-day precisions (as relative standard deviation) were less than 11% for each QC level of escin Ia and escin Ib. The accuracies (as relative error) were within ±5.27% for escin Ia and within ±4.07% for escin Ib. The method was successfully employed in a pharmacokinetic study after a single intravenous infusion administration of sodium aescinate injection containing 10 mg escin to each of the 10 healthy volunteers.

Simultaneous quantitation of dexamethasone palmitate and dexamethasone in human plasma by liquid chromatography/tandem mass spectrometry

A rapid and sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for simultaneous quantitation of dexamethasone palmitate and dexamethasone in human plasma was developed. After sample preparation by protein precipitation and liquid-liquid extraction, the analytes and internal standard (IS) were separated on a Venusil XBP-C8 column using gradient elution. Multiple reaction monitoring of dexamethasone palmitate, dexamethasone and IS used the precursor to product ion transitions at m/z 631.8-->373.1, m/z 393.2-->147.1 and m/z 264.2-->58.1, respectively. The method was linear over the ranges 1.5-1000ng/mL for dexamethasone palmitate and 2.5-250ng/mL for dexamethasone with intra- and inter-day precisions of <10% and accuracies of 100+/-7%. The assay was applied to a clinical pharmacokinetic study involving the injection of dexamethasone palmitate to healthy volunteers.

Relationship Between Apoptosis and Proliferation in Granulosa and Theca Cells of Cystic Follicles in Sows

To investigate the causes of the occurrence and persistence of porcine cystic follicles, we evaluated the apoptosis and proliferation of follicular cells in these cysts. Apoptotic frequencies were examined by TUNEL assay and the expression of apoptosis regulators (XIAP, bax, bc1-2 and caspase-3) by immunohistochemistry, Western blotting and real-time quantitative PCR; cell proliferation activity was evaluated by PCNA immunohistochemistry and proliferation of in vitro cultured granulosa and theca cells. The low apoptotic frequency and weak proliferative activity were found in cystic follicles. Low frequency of apoptosis might be associated with decreased amounts of apoptotic-related factors (bax and caspase-3) and increased amounts of anti-apoptotic factors (XIAP and bcl-2) in cystic follicles. Significantly lower proliferation activity was detected in granulosa and theca cells from cystic follicles, and lesser PCNA-positive cells were found in cystic follicles. Our results indicate that the programmed cell death and cell proliferation system were altered in cystic follicles. The disorder between apoptosis and proliferation was responsible for maintaining a static condition without degeneration, which leads to the long-term persistence of follicles. These findings provide important novel insights into the pathogenesis of follicular cysts in sows.

High Serum Levels of Follistatin in Patients with Ovarian Cancer

OBJECTIVE: This study investigated the potential use of serum follistatin (FST) as a marker for ovarian cancer alongside serum cancer antigen-125 (CA-125). METHODS: Serum samples were collected from patients with ovarian cancer (n = 45), benign ovarian cysts (n = 40) or other cancers (n = 100) and from healthy subjects (n = 60) for the determination of FST and CA-125 levels using enzyme-linked immunosorbent assays. Expression of FST in ovarian tissue was investigated using immunohistochemical staining. RESULTS: Compared with healthy subjects and patients with benign ovarian cysts, serum FST and CA-125 levels were significantly increased in patients with ovarian cancer. Using the 95% confidence interval for the healthy subjects group as the cut-off value, tumour marker sensitivity and specificity in ovarian cancer were 53.3% and 97% for FST and 77.8% and 84% for CA-125, respectively. Tissue expression of FST protein was more pronounced in ovarian cancer than in normal ovary. CONCLUSIONS: The serum FST level was elevated in the peripheral blood of patients with ovarian cancer and has potential as a tumour marker for ovarian cancer diagnosis. It may be particularly useful when combined with CA-125 detection to reduce the number of false-positive results.

Rapid and sensitive assay for trantinterol, a novel β2-adrenoceptor agonist, in human plasma using liquid chromatography–tandem mass spectrometry

A rapid and sensitive assay for trantinterol, a novel beta(2)-adrenoceptor agonist, in human plasma has been developed. Samples containing the analyte and internal standard, clenbuterol, were analyzed by liquid chromatography-tandem mass spectrometry after liquid-liquid extraction with diethyl ether:dichloromethane (60:40, v/v). Separation was performed on a Venusil MP C(18) column (50 mm x 4.6 mm, 5 microm) using methanol:1% formic acid (50:50, v/v) as mobile phase and monitored by multiple reaction monitoring of the precursor-to-product ion transitions of trantinterol at m/z 311.2-->238.1 and clenbuterol at m/z 277.2 --> 203.1. The total run time was only 1.5 min and the method was linear over the concentration range 1-1000 pg/mL with a lower limit of quantitation of 1 pg/mL. Intra- and inter-day precisions (relative standard deviation) were below 7% and 12%, respectively, with accuracy (relative error) below 8%. The method was successfully applied to a pharmacokinetic study involving oral administration of a 50 microg trantinterol tablet to healthy volunteers.

Simultaneous analysis of isomers of escin saponins in human plasma by liquid chromatography–tandem mass spectrometry: Application to a pharmacokinetic study after oral administration

A rapid and sensitive bioassay based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the simultaneous determination of four isomeric escin saponins (escin Ia, escin Ib, isoescin Ia and isoescin Ib) in human plasma has been developed and validated. Sample preparation of plasma after addition of telmisartan as internal standard (I.S.) involved solid-phase extraction (SPE) on C18 cartridges. Separation was based on reversed phase chromatography using gradient elution with methanol-acetonitrile (50:50, v/v) and 10 mM ammonium acetate solution (pH 6.8). MS/MS detection in the positive ion mode used multiple reaction monitoring of the transition at m/z 1113.8-->807.6. Stability issues with the four saponins required the addition of formic acid to plasma samples prior to storage at -80 degrees C and analysis within 30 days. The method was linear at concentrations up to 10 ng/mL with correlation coefficients>0.996 for all analytes. The lower limit of quantitation (LLOQ) for all four saponins was 33 pg/mL. Intra- and inter-day precisions (as relative standard deviation) were all <15% and accuracies (as relative error) in the range -5.3% to 6.1%. The method was successfully applied to a pharmacokinetic study of escins in healthy volunteers after oral administration of sodium aescinate tablets containing 60 mg escin saponins.

Ultra-sensitive assay for paclitaxel in intracellular compartments of A549 cells using liquid chromatography-tandem mass spectrometry.

A high-performance liquid chromatography-tandem mass spectrometric (LC-MS/MS) method for the determination of paclitaxel in intracellular compartments using docetaxel as internal standard (IS) has been developed and validated. A549 cancer cells (10(6)) were incubated with paclitaxel (2ng/mL) for up to 4h and then subjected to sequential extraction of cytosolic, membrane/organelle, nuclear and cytoskeleton soluble protein. Fractions were ultrasonicated to release protein bound paclitaxel after which drug was extracted using liquid-liquid extraction with diethyl ether:dichloromethane (2:1, v/v). Chromatographic separation was then carried out on an Ascentis Express C18 column (50mm×4.6mm, 2.7μm) with a mobile phase of acetonitrile:0.1% formic acid in water (50:50, v/v). Detection involved electrospray positive ionization followed by multiple reactions monitoring of the precursor-to-product ion transitions of paclitaxel at m/z 854.4→286.3 and docetaxel at m/z 808.6→226.1. Assay validation based on samples of total cell extract in the same buffer as protein fractions showed the assay was linear over the range 2-600pg/mL with intra- and inter-day precision (as relative standard deviation) and accuracy (as relative error) of <7% and <±12%, respectively. Recovery was approximately 70% and matrix effects were minimal. The distribution of paclitaxel in subcellular components of A549 cancer cells was mainly into the cytoskeletal compartment.

Pharmacokinetics and bioavailability of cimicifugosides after oral administration of Cimicifuga foetida L. extract to rats

ETHNOPHARMACOLOGICAL RELEVANCE Cimicifuga foetida L., a traditional Chinese medicine, has been used as an anti-inflammatory, antipyretic and analgesic remedy. The primary active constituents are believed to be present in the triterpene glycoside fraction. MATERIALS AND METHODS To develop an LC-MS/MS assay for four major cimicifugosides [cimicifugoside H-1 (Cim A), 23-epi-26-deoxyactein (Cim B), cimigenolxyloside (Cim C) and 25-O-acetylcimigenoside (Cim D)] obtained from C. foetida L. and apply it to investigate their pharmacokinetic (PK) properties and bioavailabilities through oral administration of C. foetida L. extract (12.5, 25 and 50mg/kg) and single intravenous (i.v.) doses (5mg/kg) of the individual cimicifugosides in rat. PK parameters were estimated by non-compartmental analysis. RESULTS All calibration curves showed excellent linear regressions (all r>0.995) within the range of tested concentrations. The intra- and inter-day variations were <15% in terms of RSD. The molar ratio of Cims A, B, C, and D in the extract was 20.7:1.4:2.9:1. PK parameters for Cims A, B, C, and D following oral administration of the extract were respectively: C(max) 4.05-17.69, 90.93-395.7, 407.1-1180 and 21.56-45.09pmol/mL; T(max) 0.46-1.28, 2.00-4.67, 14.67-19.67 and 8.08-14.27h; absolute oral bioavailability (F) 1.86-6.97%, 26.8-48.5%, 238-319% and 32.9-48%. PK parameters after i.v. administration of individual cimicifugosides were respectively: elimination half-life 1.1, 2.5, 5.7 and 4.2h; clearance 15.7, 0.48, 0.24 and 1.13mL/hkg. CONCLUSIONS Systemic exposure to Cims B, C and D following oral administration of the extract was significantly greater than to Cim A despite the predominance of Cim A in the extract. Significantly different clearance and interconversion from Cim A to Cim C probably accounts for the different exposure to the four cimicifugosides.

Validated LC-MS/MS method for the determination of sarpogrelate in human plasma: application to a pharmacokinetic and bioequivalence study in Chinese volunteers.

A rapid and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was established for the determination of sarpogrelate in human plasma. One-step protein precipitation with acetonitrile was used to extract the analytes from the plasma. Sarpogrelate and tramadol (internal standard, I.S.) were separated on a Venusil MP-C(18) column within 1.7 min, using acetonitrile:ammonium acetate (10 mM, pH 6.8) (55:45, v/v) as mobile phase at a flow rate of 1.2 mL/min with an approximately 1:1 split entering the mass spectrometer. Detection was performed on electrospray positive ionization mass spectrometry by multiple reaction monitoring of the transitions of sarpogrelate at m/z 430.3-->135.3 and of I.S. at m/z 264.1-->58.0. The assay was validated over the concentration range of 1-1000 ng/mL with a lower limit of quantitation (LLOQ) of 1 ng/mL using 50 microL of plasma. The intra- and inter-day precision (relative standard deviation, R.S.D.) were <or=6.4% and <or=5.4%, respectively, with accuracy (relative error, R.E.) in the range 0.5-3.6%. The method was successfully applied to a pharmacokinetic and bioequivalence study enrolling 22 Chinese volunteers administered sarpogrelate tablets.