Method for quantification of prazosin in dog plasma and its application to pharmacokinetic study

A simple and sensitive high performance liquid chromatography method using fluorescence detection （HPLC- FLD） and a one-step single solvent extraction for the determination of prazosin（PZS） in dog plasma is developed and validated. After extraction with ether, the chromatographic separation of PZS is carried out using a reverse phase C18 column （ 150 mm ×4.6 mm, 5 μm） with a mobile phase of 30% acetonitrile and 70% acetic acid-sodium acetate buffer solution （pH = 3.6） and quantified by fluorescence detection operated with an excitation wavelength of 258 nm and an emission wavelength of 387 nm. The flow rate of the mobile phase is 1.0 mL/min and the retention time of PZS and the internal standard is found to be 4. 4 and 5. 8 rain, respectively. The calibration curve is linear within a concentration range from 1.0 to 1 000.0 ng/mL （ P 〉 0. 998）. The limit of detection is 0.4 ng/mL. The inter-day coefficient of variation （COV） of the calibration standards is below 5.0% and the mean accuracy is in the range from 92. 7% to 104. 2%. Moreover, by analyzing quality control plasma samples for three days, the results show that the method is precise and accurate, for the intra- and inter- day COV within 10% and the accuracy from 95.9% to 112.7%. The developed and validated method is successfully applied to phannacokinetic study for the preclinical evaluation of a new peroral PZS-sulfobutyl ether beta-cyclodextrin （PZS-SBE-β-CD） inclusion complex tablets （test preparation）, which demonstrates that the test preparation released PZS is conducted in a slow and controlled way, and the relative bioavailability of the test preparation is found to be 105.0%.

Analysis of three types of triterpenoids in tetraploid white birches(Betula platyphylla Suk.) and selection of plus trees

Betulin, oleanolic acid, and betulinic acid are naturally occurring pentacyclic triterpenoids that have significant medicinal value. Considerable amounts of these triterpenoids are available in the outer bark of white birch. In this study, we used ultrasound-assisted extraction （UAE） to extract triterpenoids from birch bark rapidly and with high efficiency. Using high performance liquid chro- matography （HPLC）, three types of triterpenoids were separated and detected. We examined the differences among triterpenoids extracted from diploid versus tetra- ploid white birch. Then, we used factor analysis to screen out tetraploid white birches with comprehensively excel- lent performance. The results indicate that the optimum conditions for extraction include the use of ethanol as an extraction solvent, a solid-to-liquid ratio of 0.1 g/10 ml, ultrasonic power set at 100 W, a temperature of 60 ℃ and an extraction time of 15 min. A reversed-phase C18 col- umn （4.6 mm × 250 mm × 5 μm） with a column tem- perature of 30 ℃ and the mobile phase composed of A （acetonitrile） and B （0.1% aqueous phosphoric acid, v/v） at a flow rate of 0.5 ml/min were used, and the detection wavelength was 195 nm. No significant difference wasobserved between diploid and tetraploid white birch in terms of the content of three types of triterpenoids （at a confidence level of 0.05）. As triterpenoid content, height, and DBH （diameter at breast height） are strongly interre- lated, we used factor analysis to evaluate all individuals, and we screened out six plus trees with excellent com- prehensive characters.

Pressured Microwave-assisted Hydrolysis of Crude Glycyrrhizic Acid for Preparation of Glycyrrhetinic Acid

A pressured microwave-assisted hydrolysis （PMAH） technique has been developed for hydrolyzing the crude glycyrrhizic acid （GA） extracted from licorice root to prepare glycyrrhetinic acid （GRA）. In order to optimize the efficiency of PMAH, several experimental parameters were investigated, including liquid-solid ratio, hydrolysis time, sulfuric acid concentration and hydrolysis temperature. The optimized hydrolysis conditions were as follows：pressured microwave-assisted hydrolysis of crude GA for 21 min （taking 15 min to reach 150 ℃, and holding it for 6 rain） at 150 ℃ （at a radiation power of 450 W） in 3%-5% sulfuric acid solution with the liquid-solid （ml.g-1 crude GA） ratio of 25 ： 1. As a result of the considerable saving in time and higher product yields （up to 90%）, PMAH was proved more effective than conventional methods.

The ocular toxicity and pharmacokinetics of simvastatin following intravitreal injection in mice

AIM：To investigate the retinal toxicity and pharmacokinetics of simvastatin intravitreally injected into mice.METHODS：Forty-eight 6-8-week-old C57BL/6J mice were used in this study.Simvastatin was intravitreally injected into the right eye of each mouse;the left eye was injected with vehicle and was used as a control.Bilateral dark-adapted electroretinography（ERG）was performed 1 and 7d following injection.Histology was examined using a combination of light,fluorescence and electron microscopy.Highperformance liquid chromatography（HPLC）was used to determine the decay in the retinal simvastatin concentration.RESULTS：ERG revealed no significant changes in the simvastatin-injected eyes compared to control.Histologic studies showed normal retinal morphology in eyes injected with simvastatin up to a final vitreal concentration of 200μmol/L.No significant changes in the number of photoreceptors,bipolar cells or ganglion cells were found.The retinal simvastatin concentration decayed exponentially,with a half-life of 1.92-2.41h.CONCLUSION：Intravitreal injection of up to 200μmol/L simvastatin produced no signs of adverse effects in the mouse retina.Simvastatin reaches the retina shortly after intravitreal injectionand has a short half-life.

Mutation screening of mismatch repair gene Mlh3 in familial esophageal cancer

AIM： To shed light on the possible role of mismatch repair gene MIh3 in familial esophageal cancer （FEC）. METHODS： A total of 66 members from 10 families suggestive of a genetic predisposition to hereditary esophageal cancer were screened for germline mutations in MIh3 with denaturing high performance liquid chromatography （DHPLC）, a newly developed method of comparative sequencing based on heteroduplex detection. For all samples exhibiting abnormal DHPLC profiles, sequence changes were evaluated by cycle sequencing. For any mutation in family members, we conducted a segregation study to compare its prevalence in sporadic esophageal cancer patients and normal controls. RESULTS： Exons of MIh3 in all samples were successfully examined. Overall, 4 missense mutations and 3 polymorphisms were identified in 4 families. MIh3 missense mutations in families 9 and 10 might be pathogenic, but had a reduced penetrance. While in families 1 and 7, there was no sufficient evidence supporting the monogenic explanations of esophageal cancers in families. The mutations were found in 33% of high-risk families and 50% of low-risk families.CONCLUSION： MIh3 is a high risk gene with a reduced penetrance in some families. However, it acts as a low risk gene for esophageal cancer in most families. Mutations of MIh3 may work together with other genes in an accumulated manner and result in an increased risk of esophageal tumor. DHPLC is a robust and sensitive technique for screening gene mutations.

harmacokinetics of Tetramethylpyrazine Phosphate inHealthy and Blood Stasis Dogs in vivo

To test the hypotliesis of Syndrome and Treatment Pharmacokinetics (S-TPK ) , tlie authorsbeve stodied tlie pharmacokinetics of tetramethyrazine phosphate (TMPP) in healthy and blood stasis dogs byhigh performance liquid chromatography. After a single intravenous injection ot TMPP & mg` kg i to healthyand blood stasis dogs, compartment model of TMPP serum concontration was fitted and then pharmacokineticparameters were calculated with a Microcomputer Pharmacokinetic Program on a Compaq 80386 computer.lmportant parameters were as follows: in the healthy dogs, T1/2 = 30. 27 ±6. 85 min. Kel = 0. 11 ± 0. 04min-1 , AUC = 445. 26 ± 51 . 26 mg/L.min , in the blood stasis dogs, min, Kel = 0. 06±0 . 01 min -1 , AUC = 1381 . 85 ± 464 . 68 mg/L. min. Through this experiment it was found that there was sig-nificant differefico in the pharmacokinetic parameters between healthy and blood stasis dogs. The results ob-tained are consistent with S-TPK hypotbesis.