Biomedical subjects
Publications and source records attributed to A R Liu.
A method for the determination of taxol in Taxus chinensis by HPLC method using betamethasone as internal standard is described. The column employed was packed with 10 microns silica gel YWG 80 (250 x 4 mm), the eluting solvent consisted of CH2Cl2--MeOH (95:5) and the effluent was monitored at 228 nm. The coefficients of variation are less than 2%.
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A method for the determination of ranunculin in Pulsatilla chinensis and synthetic ranunculin by reversed phase HPLC using betamethasone as internal standard is described. The column employed was a 10 micron LiChrosorb RP-18 (230 x 14 mm), the eluting solvent consisted of methanol-water (40:10, V/V) and the effluent was monitored at 225 nm. The advantages of this method are simple, rapid and accurate. The coefficients of variation are less than 1%.
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A method for the quantitative determination of three main bile acids, cholic acid (CA), ursodesoxycholic acid (UDCA) and chenodesoxycholic acid (CDCA), in bear gall, drainage from bear gall and bear gallstone is described. Experimental conditions: TLC Scanner CS-910, fluorescence scanning, lambda ex 470 nm and lambda em 550 nm for CA; lambda ex 380 nm and lambda em 450 nm for UDCA and CDCA. The results showed that the contents of UDCA and CDCA in bear gall drainage were higher than those in bear gall. The method is simple, rapid and sensitive. The reproducibility is good. The average recovery is 98.4%, CV is 1.4%.
A method for the determination of total flavonoids in Sophora japonica L. by coulometric titration was developed. The titration was carried out in a mixture of 1 mol/L KBr--2 mol/L HCl (1:1) and bromine was generated at the anode, rutin reacted with two moles of bromine with an n value of 4. The advantages of this method are simple and rapid, it can be used to analyze small amount of sample.
Metabolic changes were investigated in two groups of women using oral contraceptives for 5 to 16 years. Blood samples were taken during the last cycle of oral contraceptive use and three months post-treatment. One group had used a monthly oral contraceptive (MOC, 3mg quinestrol and 10mg 16-methylene chlormadinone acetate) and the second group a daily oral contraceptive (DOC, 35 micrograms ethynylestradiol and 0.625 mg norethisterone). During treatment there were increases in serum total cholesterol and triglycerides but not HDL-C, in plasma total cortisol but not in renin activity, angiotensin II or urinary free cortisol excretion, in hemoglobin and some coagulation factors but not Factor X or antithrombin III, platelet function or fibrinolysis. The area under the blood glucose concentration-time curve, but not that for serum insulin, was slightly increased and there was no change in fasting blood sugar concentrations. All metabolic parameters, except plasma cortisol, which had shown an increase on treatment, had decreased to control levels within 3 months. Ovulation returned promptly in all women, the mean time being 70 days for Group MOC and 44 days for Group DOC. Thus, in spite of the long duration of use of the oral contraceptives, metabolic changes were minor.
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