High-performance liquid chromatographic determination of glibenclamide in human plasma and urine

A selective and sensitive high-performance liquid chromatographic method for determination of intact glibenclamide in human plasma or urine has been developed. With glibornuride as internal standard, acid-buffered plasma or urine was extracted with benzene. The organic layer was evaporated and the residue was dissolved in equilibrated mobile phase (acetonitrile-phosphate buffer 0.01 M pH 3.5, 50:50). An aliquot of 20 microliters was chromatographed on a Spherisorb ODS reversed-phase column, and quantitation was achieved by monitoring the ultraviolet absorbance at 225 nm. The response was linear (0-1000 ng/ml) and the detection limit was 5-10 ng/ml in plasma or urine. The within-assay variation was less than or equal to 10%. No interferences from metabolites or endogenous constituents could be noted. The utility of the method was demonstrated by analysing glibenclamide in samples from diabetic subjects on therapeutic doses of the drug.     

High-performance liquid chromatographic method for the analysis of Oltipraz in human serum and urine.

A rapid, sensitive procedure for the analysis of Oltipraz in serum and urine using high-performance liquid chromatography was developed. The proposed method illustrates recovery of Oltipraz from biological fluids was greater than 80%. Detection and separation of Oltipraz required as little as 1 ml of serum or urine. Oltipraz was detectable when 2 ng or more of drug was present in 1 ml of serum or urine; the method is highly reproducible when 5 ng/ml or more Oltipraz is present in the biological fluid.     

Coupling of chromatographic ion-exchange reaction with change-partner reaction. Presumed mechanism on the ion-ion interaction of inorganic ions in Sephadex G-15 columns

A sample solution containing sodium or potassium dihydrogenphosphate or disodium or dipotassium hydrogenphosphate was eluted from a Sephadex G-15 column with either sodium or potassium chloride solution in various sample-eluent systems, and every one of the four kinds of ions employed was determined in the eluate. Then, the elution profiles showed the phenomenon that a negative peak of chloride ion coexisted in the fractions of a positive peak of phosphate ion, in all sample-eluent systems employed. This phenomenon was assumed to occur by the coupled reaction of change-partner and ion-exchange reactions including ion exclusion.     

Comparison of dry and wet ashing procedures for cadmium and iron determination in biological material by atomic-absorption spectrophotometry

A possible loss of cadmium and iron from the sample during dry ashing of the kidney, liver or carcase was examined by the radioactive isotope labelling technique. Cadmium-115 m or iron-59 was administered to rats 4-7 days before the rats were killed and samples collected. Dry ashing in different types of dishes and wet digestion with nitric acid were compared. There was no loss of cadmium or iron by volatilization during dry ashing at 600 degrees or 450 degrees respectively, but a significant amount of iron was bound on glass or porcelain crucibles. Storage of ashed and dissolved samples (in 10 nitric acid) did not show any change of cadmium or iron concentration up to 9 days.     

Kinetics and mechanism of the benzoin isobutyl ether photoinitiated polymerization of styrene

The kinetics of the photopolymerization of styrene in bulk and in dilute systems in the presence of benzoin isobutyl ether as photoinitiator have been examined. The values of the intensity exponent, calculated at different temperatures or at different styrene concentrations, and the monomer exponent, calculated at various intensities, showed significant departure from those predicted by the ideal kinetic scheme, particularly at high intensity, at low temperature, or at low styrene concentrations. Low molecular weight polymer was the dominant product when high light intensity or low polymerization temperature was used. As the temperature was raised, however, or as the intensity was reduced, a high molecular weight polymer became progressively more important. Kinetic and molecular weight data suggest that at low temperature, high intensity, and/or at low monomer concentration, the benzoyl radical is the dominant initiating species; and the benzyl ether radical was consumed mainly in the termination step. At low intensity, high temperature and/or high monomer concentration, however, it appears that both benzoyl and benzyl ether radicals initiated polymerization.     

PROFLAVIN CATALYZED PHOTOPRODUCTION OF HYDROGEN FROM ORGANIC COMPOUNDS

Abstract— Methyl viologen was reduced by EDTA and other organic compounds when aqueous solutions of these compounds were irradiated near 440 nm in the presence of catalytic quantities of proflavin. The photoreduced methyl viologen was readily oxidized in the dark by the enzyme hydrogenase or platinum asbestos. When the entire reaction was run in the light with hydrogenase or platinum, continuous production of hydrogen was observed. The yield of hydrogen was approximately stoichiometric to the EDTA present establishing that methyl viologen and proflavin were acting catalytically. To establish the structural requirements of the electron donor, eighty compounds were tested at seven pH values between 4 and 10. Of these, twenty served as electron donors for the photoproduction of hydrogen. The effective donors contained either a secondary or tertiary nitrogen atom with one or more carboxymethyl or β-hydroxyethyl groups, or a sulfhydryl group. The system could also reduce benzyl viologen but not methylene blue. Riboflavin did not replace proflavin for the photoproduction of hydrogen, This system may have potential for producing hydrogen with solar energy.     

Matrix effect in the cryotrapping of gas samples in the ppbv range

A gas mixture containing ppbv concentrations of volatile chlorinated and aromatic hydrocarbons was prepared in helium, nitrogen, or argon in a plastic (Nalophan) bag, in which it was found the mixture could be safely stored for several days. Samples of the mixture were subsequently analyzed by gas chromatography after direct cryotrapping in an empty metal U-tube. The cooling medium used was liquid nitrogen, liquid argon, or a dry ice-acetone slurry (197 K). The efficiency of cryotrapping in liquid nitrogen was over 90% when the aromatic hydrocarbon mixture was prepared in the helium matrix, but between 50 and 70% when it was prepared in nitrogen or argon, the recovery from the argon matrix being somewhat higher. The poor recovery in nitrogen at 77 K and argon at 87 K was explained by the reduced rate of diffusion to the wall owing to mist or aerosol formation. At 197 K condensation was negligible if the partial pressures were lower than the saturated vapor pressures.     

O-二异丙氧磷酰基丝氨酸(或苏氨酸或酪氨酸)的合成

介绍一种简单方便地合成O-二异丙氧磷酰基丝氨酸(或苏氨酸或酪氨酸)的方法.其中O-二异丙氧磷酰基-L-丝氨酸(或苏氨酸)可从对应的N-磷酰化-L-丝氨酸(或苏氨酸)利用磷酰基N→0迁移的性质并在超声辅助下合成,而N-二异丙氧磷酰基-L-丝氨酸(或苏氨酸)的合成由L-丝氨酸(或苏氨酸)在次氯酸钠的水溶液中高收率地获得.O-二异丙氧磷酰基酪氨酸的合成可通过铜盐同时保护氨基和羧基,使用二异丙基磷酰氯为磷酰化试剂磷酰化,用硫化氢脱铜保护制备.     

Study on Au/Al2O3 catalysts for low-temperature CO oxidation in situ FT-IR

Au/Al2O3 catalyst was prepared by a modified anion impregnation method and investigated with respect to its initial activity and stability for low-temperature CO oxidation. The activity changes of the catalyst were examined after separate treatment in CO+O2 or CO2+O2. Furthermore, in situ FT-IR studies were performed to investigate the species on the surface when CO or CO+O2 or CO2+O2 was selected separately as adsorption gas. The results showed that Au/Al2O3 catalyst exhibited very high initial activity, but the catalytic activity was found to decrease gradually during CO oxidation with time on stream. And also, the activity of the catalyst declined after treatment in CO+O2 or CO2+O2. The formation and accumulation of carbonate-like species during CO oxidation or treatment in CO+O2 or CO2+O2 might be mainly responsible for the activity decrease, which was reversible.     

High-performance liquid chromatographic determination of glipizide in human plasma and urine

A sensitive and selective high-performance liquid chromatographic method for determination of intact glipizide in human plasma or urine has been developed. The plasma and urine samples were acid-buffered, before tolbutamide was added as internal standard. The samples were extracted with benzene, and the organic layer was evaporated to dryness. The residue was dissolved in equilibrated mobile phase (acetonitrile-0.01 M phosphate buffer pH 3.5, 35:65), and an aliquot of 20 microliters was chromatographed on a Spherisorb ODS reversed-phase column. Quantitation was achieved by monitoring the ultraviolet absorbance at 275 nm. The response was linear (0-1000 ng/ml) and the detection limit was 5-10 ng/ml in plasma or urine. The within-assay variation was less than or equal to 10%. No interferences from metabolites or endogenous constituents were observed. The utility of the assay was demonstrated by determining glipizide in samples from a diabetic subject receiving a therapeutic dose of 5 mg of the drug.     

DNA与Rt、VB2相互作用的电化学性质

芦丁(Rt)是存在于多种植物体中的一种多羟基黄酮化合物,是某些中草药的有效成分。本文在前文基础上着重对芦丁、VB2在玻碳电极上的电化学性质、二者与DNA相互作用的机理等方面的差异进行比较,这对维生素类药物与生物大分子相互作用的研究与应用具有重要意义。     

Enantiomeric separation by cyclodextrin modified capillary zone electrophoresis (CD-CZE) of quaternary tetrahydroprotoberberine alkaloids

A cyclodextrin modified capillary zone electrophoresis (CD-CZE) for the enantiomeric separation of tetrahydroprotoberberine N-metho salts was established. The resolution was optimized by changing the concentration of the electrolyte solution, hydroxypropyl-beta-CD (0.02 M, 0.07 M, or 0.14 M) or dimethyl-beta-CD (0.05 M or 0.15 M) in phosphate buffer (pH 2.5 or 3) containing 10% acetonitrile with an applied voltage of 20 kV. This method was applied toward the enantioselective bio-conversion of quaternary tetrahydroprotoberberine N-metho salts in cultured cells of Corydalis species.     

Thermoplastic elastomer based on high‐density polyethylene/natural rubber blends: rheological,thermal, and morphological properties

Thermoplastic elastomer (TPE) comprising air‐dried sheet or natural rubber (ADS or NR) and high‐density polyethylene (HDPE) was prepared by a simple blending technique. NR and HDPE were mixed with each type of phenolic compatibilizer (HRJ‐10518 or SP‐1045) or liquid natural rubber (LNR) at 180°C in an internal mixer. The mixing torque, shear stress, and shear viscosity of the blends increased with increasing amounts of NR. Positive deviation blend (PDB) for the blends containing active hydroxyl methyl phenolic resin in HRJ‐10518 or dimethyl phenolic resin in SP‐1045 was obtained. PDB was not observed for the blends without the compatibilizers or with LNR. The blends with HRJ‐10518 or SP‐1045 were compatible or partially compatible while the LNR blends were incompatible. In the phenolic compatibilized blends, NR dispersed in the HDPE matrix was found in the NR/HDPE blends of 20/80, 40/60, and 50/50 ratios. HDPE dispersed in NR matrix was obtained in the NR/HDPE blend of 80/20 ratio, and the co‐continuous phase was accomplished in the NR/HDPE blend of 60/40 ratio. The NR/HDPE blend at 60/40 ratio compatibilized with HRJ‐10518 and fabricated by a simple plastic injection molding machine exhibited higher ultimate tensile strength and elongation at break (EB). Incorporation of parafinic oil caused a decreasing tendency in tensile strength with increases in EB. The TPNRs exhibited high elastomeric nature with low‐tension set. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis of 2'-deoxyadenosine nucleosides bearing bipyridine-type ligands and their Ru-complexes in position 8 through cross-coupling reactions

The synthesis of the title 2'-deoxyadenosine derivatives bearing bipyridine, phenanthroline or terpyridine ligands and their corresponding RuII-complexes in position 8 linked via acetylene or phenylene tethers was accomplished through cross-coupling reactions. The Suzuki-Miyaura reactions of boronic acids or the Sonogashira reactions of terminal acetylene derivatives of oligopyridine ligands were performed either on protected 8-bromoadenosines in organic solvents or, more efficiently, directly on unprotected nucleosides in aqueous acetonitrile or DMF. Direct cross-coupling reactions of unprotected nucleosides with RuII-complexes or the oligopyridine-boronic acids or -acetylenes gave the Ru-labelled nucleosides in one step in fair to good yields. This method was also proven to be applicable for direct Ru-labelling of dATP. Terpyridine-containing 2'-deoxyadenosine exerted significant antiviral and cytostatic effects.     

Regioselection and orthogonality of the 1-phenyl-3-butenyl (PBU) protecting group in glucopyranosides

The 1-phenyl-3-butenyl (PBU) protecting group was alternatively introduced in position 4 or 6 by regioselective opening of methyl 2,3-di-O-benzyl-4,6-O-benzylidene-alpha-D-glucopyranose with allyltrimethylsilane in the presence of the Lewis acid promoters TMSOTf or AlCl3. The PBU group was selectively removed, in presence of t-butyldimethylsilyl, trityl or acetyl protecting groups, with acids (TFA) or using Pd(CH3CN)2Cl2.     

Mass fragmentographic determination of 4-hydroxy-3-methoxyphenylglycol (HMPG) in urine, cerebrospinal fluid, plasma and tissues using a deuterium-labelled internal standard.

4-Hydroxy-3-methoxyphenylglycol (HMPG) with the three hydrogen atoms in the side-chain replaced with deuterium (HMPG-D3) was used as the internal standard in the mass fragmentographic determination of free and conjugated HMPG in human urine, cerebrospinal fluid and plasma and in rat urine, liver and brain. HMPG-D3 was added to body fluids or homogenates followed by enzymatic hydrolysis of conjugates. HMPG was extracted with ethyl acetate, converted into the trifluoroacetyl derivative and analyzed by mass fragmentography. HMPG levels were 7.4 nmoles/ml plus or minus 2.8% in human urine, 73 pmoles/ml plus or minus 8.2% in human cerebrospinal fluid, 56 pmoles/ml plus or minus 5.4% in human plasma, 24 nmoles/ml plus or minus 3.6% in rat urine, 0.26 nmoles/g plus or minus 6.2% in rat brain and 99 pmoles/g plus or minus 13% in rat liver. The method is highly specific and sensitive, permitting analysis in small samples or in plasma and in tissues for which previously no methods for HMPG analysis were available.     

Study on Au/Al_2O_3 catalysts for low-temperature CO oxidation in situ FT-IR

Au/Al2O3 catalyst was prepared by a modified anion impregnation method and investigated with respect to its initial activity and stability for low-temperature CO oxidation.The activity changes of the catalyst were examined after separate treatment in CO+O2 or CO2 +O2 .Furthermore,in situ FT-IR studies were performed to investigate the species on the surface when CO or CO+O2 or CO2 +O2 was selected separately as adsorption gas.The results showed that Au/Al2O3 catalyst exhibited very high initial activity,but the catalytic activity was found to decrease gradually during CO oxidation with time on stream.And also,the activity of the catalyst declined after treatment in CO+O2 or CO2 +O2 .The formation and accumulation of carbonate-like species during CO oxidation or treatment in CO+O2 or CO2 +O2 might be mainly responsible for the activity decrease,which was reversible.     

Studies on the stereoselective selenolactonization, hydroxy and methoxy selenenylation of α- and β-hydroxy acids and esters. Synthesis of δ- and γ-lactones

The diastereoselective synthesis of hydroxy substituted γ- and δ-lactones was accomplished following two approaches. A 5- or 6-endo cyclization promoted by electrophilic selenium reagents of α- or β-hydroxy acids and a 5- or 6-exo cyclization of hydroxy esters obtained through a diastereoselective hydroxy selenenylation reaction of α- or β-hydroxy esters. Moreover, the diastereoselective methoxy selenenylation of the above compounds was investigated showing a case in which the compound that was unreactive in the hydroxy selenenylation conditions gave, in the methoxy selenenylation conditions, the deprotected diol. The usefulness of the methoxy selenenylation procedure was proven by the preparation of a symmetric compound unsymmetrically functionalized. Yields and selectivities were found to depend on substituents (Ph or alkyl groups at the carbon atom that undergoes the nucleophilic attack), mode of cyclization, kinetic or thermodynamic control conditions. In the latter case, silica gel played an important role.     

螺旋藻蛋白色素的稳定性研究

本文考察了螺旋藻蛋白色素（SP）的干粉和溶液的稳定性。SP干粉在暗处和室内自然光下较稳定，直射光下稍差。SP溶液在PH6～7时色泽呈蓝色，Cu2+对其稳定性有破坏作用，EDTA和柠檬酸可增强SP溶液稳定性，而明胶对其无影响，山梨酸对SP溶液色泽有良好的保护作用，SP在10％乙醇溶液或50％甘油溶液中较稳定。     

钙离子体系中隐式和显式内随机共振

近年来, 细胞内钙离子信号及其产生机理已成为研究热点之一, 这是因为钙离子信号能控制细胞的生死、 传递细胞间的信息、 提高基因表达的有效性和特殊性[^1~3]. 在钙离子信号传递过程中, 受环境扰动是不可避免的. Shuai等^[4]发现噪音能够控制钙离子通道中钙离子的释放. 在过去的十年中, 无论是物理、 化学还是生物体系^[5~10]的噪音效应已被广泛研究, 其中包括对随机共振(SR)的研究^[5], 经典SR是环境噪音能够放大弱的外加信号. 但随着研究的深入, 发现有无噪音SR^[11]和内SR(ISR) ^[6]. ISR的内信号来自噪音诱导的内信号, 这种SR现象叫隐式内SR(IISR). 而我们则发现了另外一种内SR, 即显式内SR(EISR) ^[12], 它的内信号是体系固有的内信号, 而不是由噪音诱导的. 本文主要研究加入外信号将对IISR和EISR产生的影响.