HPLC study of tissue distribution of loganin in rats

A rapid, sensitive and selective high performance liquid chromatography (HPLC) method was developed and validated for determination of loganin in rat tissues. Samples were prepared based on a simple protein precipitation. Separation of loganin was achieved on a reversed-phase C(18) column (250 x 4.6 mm, 5 microm) with a mobile phase consisting of acetonitrile and water (16:84, v/v) at a flow rate of 1.0 mL/min. The detection wavelength was set at 236 nm and the temperature of the column was kept at 30 degrees C. The method was applied to study tissue distribution of loganin in rats after a single administration of loganin at a dose of 20 mg/kg. The highest level was observed in kidney, then in stomach, lung and small intestine. The lowest level was found in brain. The peak levels were attained at 90 min in most tissues. It was indicated that kidney was the major distribution tissue of loganin in rats, and that loganin had difficulty in crossing the blood-brain barrier. It was also found there was no long-term accumulation of loganin in rat tissues.     

Influence of the morphology of samples in the pyrolysis of PVC

PVC was used as a model substance to study the dependence of thermal measurement data on the preparation and morphological characteristics of samples The PVC treated was a commercially available suspension polymer, Ongrovil S 155, produced by the Borsodi Vegyi Kombinát. The whole thermal process was followed by TG and DTG measurements in air and argon atmospheres by means of a Du Pont 990 Thermoanalyzer. Evolved-gas analysis was performed with a home-made apparatus. Pyrolysis gas chromatography was accomplished using a Hamilton type pyrolyzer and a Carlo Erba Chromatograph furnished with a flame ionization detector. The investigations showed benzene and other components to be evolved from the initial polymer and an alteration depending on the morphological characteristics of the samples. This was suggested to be due to the different mechanisms of thermal degradation of the PVC.     

Immobilization of ultra-thin layer of monoclonal antibody on glass surface

When preparing an affinity column and a biosensor, it is desirable to immobilize a unimolecular layer of pure protein on a matrix. In this work, we tried to immobilize a monoclonal antibody on a surface of a glass test-tube as a model, to confirm the stability of this ultra-thin layer by an enzyme immunoassay, and to estimate the thickness of the layer on a slide glass by Fourier transform infrared reflection spectrometry. A new test-tube was washed and dried. The tube was filled with 5% 3-aminopropyltriethoxysilane. The 3-aminopropylsilylated surface was treated with glutaraldehyde and 5.6.10(-2) mg/ml solution of a normal mouse monoclonal antibody. The Schiff base between glutaraldehyde and the antibody was further reduced with 7.9.10(-3)% NaBH4. The tube was washed with 0.05% Tween 20 to block non-specific binding. The antibody immobilized on the surface was measured by an enzyme immunoassay based on a reaction of anti-mouse immunoglobulin G labelled with alkaline phosphatase, with which p-nitrophenol was produced from p-nitrophenylphosphate as a substrate. Meanwhile, various amounts of the antibody were immobilized on slide glasses in the same manner. The antibody on each surface was measured by Fourier transform infrared reflection spectrometry. The antibody immobilized under the final conditions was detectable by the enzyme immunoassay, and stable at 4 degrees C for ten days. The antibody on the slide glass was a unimolecular layer, as judged from the Fourier transform infrared spectra referred to -CONH- band semiquantitatively. Thus, we found the optimal conditions for immobilizing an ultra-thin layer of the monoclonal antibody on the glass surface.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prediction of the lifetime of nitrile-butadiene rubber by FT-IR.

A quantitative measurement method with FT-IR was proposed for a thermal degradation analysis of nitrile-butadiene rubber (NBR). An NBR film was prepared as a model sample on a barium fluoride (BaF2) crystal plate, which was subjected to a heat treatment. The absorbances of various functional groups were measured directly by FT-IR after thermal degradation at high temperatures. By measuring the absorbances, it was possible to readily determine quantitatively each of the functional groups after the degradation of NBR. By assuming that the NBR lifetime was the point at which the absorbance of a carbon-carbon double bond reaches 45% of that prior to thermal treatment, a method for predicting the lifetime of NBR heated below 150 degrees C was proposed, by using an Arrhenius plot of the heating time versus heating temperature.     

WO2.90在烯烃催化氧化反应中的应用

本文研究大表面积的WO_2.90^[1]对丙烯的热脱附作用,并以丙烯和环己烯作为直链和环状烯烃的典型化合物,初步探讨其催化氧化性质。     

Study of the self-assembling of n-octylphosphonic acid layers on aluminum oxide

The deposition of n-octylphosphonic acid on aluminum oxide was studied. The substrate was pretreated in order to achieve a root-mean-square roughness of <1 nm, a hydroxyl fraction of 30%, and a thickness of approximately 170 nm. It was proven using X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) that, rather than a monolayer, an organic multilayer was formed. The growth mechanism was identified as a Stranski-Krastanov one. It was also shown that the use of AFM, probing the surface topography, is essential for a reliable quantification and interpretation of data obtained with XPS.     

Determination of nitrite by inhibition of the chemiluminescence of acriflavine in a flow-injection assembly

The indirect determination of nitrite was performed with a flow-injection assembly on the basis of the inhibition of the analytical output obtained in a luminometer by oxidation of acriflavine. The acriflavine solution merged with the nitrite and the resulting mixture was injected into a pure water stream. This solution merged with the oxidant solution (potassium permanganate in sulfuric acid medium) and the resulting chemiluminiscence was affected (inhibited) by the presence of nitrite after reaction with the aminoacridine. The method was applicable over the range 10-800 microg l(-1) of nitrite with a correlation coefficient of 0.9960. The relative standard deviation was 1.4% and the throughput was 76 samples h(-1). The influence of foreign substances was also tested. A solid-phase reactor, filled with Amberlite IRA-900, was inserted in the assembly for the on-line preconcentration of nitrite; the analytical output resulted in an increase of up to 11.5-fold. The method was applied to the determination of nitrites in residual waters, industrial formulations and soil samples.     

Percutaneous absorption of 1,3-dinitroglycerin and a trial of pharmacokinetic analysis

In order to estimate the pharmaceutical usefulness of 1,3-glyceryl dinitrate (1,3-GDN), an active metabolite of nitroglycerin, a trial transdermal delivery system designed to sustain a suitable plasma concentration of 1,3-GDN was produced using a porous membrane (Hipore 2100 or 4500) and it was a gel base or ethylhexyl acrylate-based adhesive (adhesive) and it was applied to rats. Additionally, for practical use of the transdermal system, a simple pharmacokinetic model to describe plasma 1,3-GDN levels after percutaneous (p.c.) application is presented. As a result, the drug was penetrated through the rat skin in vitro at a zero-order rate, although the penetration rate from the gel base was significantly greater than that from the adhesive. In vivo, the drug was rapidly absorbed through the rat skin, with a peak plasma level of 581 +/- 151 and 265 +/- 62 ng/ml for the gel ointment and adhesive systems without a porous membrane, respectively. The plasma levels after application of the systems with a membrane were relatively constant for a long time, indicating that the membranes act as a controlled-release barrier. The bioavailability of 1,3-GDN after gel base systems with and without a membrane was relatively high. The model presented was successfully able to describe the time course of plasma 1,3-GDN concentrations following p.c. application of the systems.     

电感耦合等离子体原子发射光谱法测定钒铁中8个杂质元素含量和方法精密度的验证

提出了电感耦合等离子体原子发射光谱法(ICP-AES)测定钒铁中硅、磷、铝、锰、镍、铬、铜、钛共8个杂质元素含量的方法。钒铁样品(0.5000g),先后加入50%(体积分数)硝酸溶液20mL及50%(体积分数)盐酸溶液10mL,在100℃左右加热溶解,溶解过程中应注意保持溶液体积在25mL左右。将溶液过滤并置于200mL容量瓶中作为母液留用。将滤纸及不溶物一并移入铂坩埚中,置于马弗炉中,先于250℃灰化20min,稍冷后加入无水碳酸钠和硼酸(质量比2∶1)组成的混合熔剂0.3g,升温至950℃融熔15min。冷却,用体积比1∶10的盐酸溶液10mL浸出熔块,将此溶液与上述母液合并并加水定容至200mL。此溶液供ICP-AES在仪器工作条件下进行分析。绘制校准曲线时,加入纯铁和五氧化二钒作为基体,以消除基体干扰,然后加入上述8种元素的标准溶液,并按上述溶液最终稀释体积条件和仪器工作条件制作曲线(R大于0.999)。为验证所提出的分析方法的测定数据的精密度,约请了10个实验室对8个不同含量水平的钒铁样品对方法作协同试验,按GB/T 6379.2-2004所规定的方法求算了重复性标准偏差Sr和重复性限r,以及再现性标准偏差SR和再现性限R,并求得所测定的8种元素在各自的测定范围内的r与w之间和R与w之间的函数关系,说明该方法有较好的稳定性和准确性,而且证明此方法是可行的。     

Mechanism of Thermal Decomposition of Barium Benzoate

Barium benzoate was synthesized in a hydrothermal reaction. The complex was characterized by elemental analysis, IR spectroscopy and X-ray powder diffraction. It was monoclinic and had a layered structure. The mechanism of thermal decomposition of the barium benzoate was studied by using TG, DTA, IR and gas chromatography-mass spectrometry. In a nitrogen atmosphere, the barium benzoate decomposed to form BaCO₃ and organic compounds: mainly benzophenone, triphenylmethane, etc.This revised version was published online in November 2005 with corrections to the Cover Date.     

The photoelectrochemical initiation of polymerization of styrene

A TiO₂ semiconductor was immersed in a solution that contained styrene monomer and a supporting electrolyte. Polymer was formed when light was focused on the semiconductor. The yield was a function of the bias level maintained at the semiconductor elecotrode. With methylmethacrylate monomer direct photoinitiation of the monomer occurred, but the polymer yield could be reduced by varying the electrode potential.     

Construction of the Skeleton of Phthalascidin, Mechanism of the Formation of the Key Tricyclic Lactam Intermediate

Phthalascidin is a structurally simplified version of Et-743, which is a potent anti-tumor marine natural product isolated from Ecteinascidia turbinata. Its antiproliferative activity is greater than that of the agents taxol, camptothecin, adriamycin, mitomycin C, cisplatin, bleomycin, and etoposide by 1-3 orders of magnitude. An elegant synthesis of Et-743 and phthalascidin has been reported by E. J. Corey and co-workers1,2. As part of our continuing program, we have also engaged in dev…     

Construction of High Expression Plasmid of Human Augmenter of Liver Regeneration （ hALR）, Expression and Purification of hALR

Introduction Theliverisoneoftheorgansthathaspotentialre generativecapabilityinmammaliananimals[1].Studies oncaninemodelshaveindicatedthatthelivercanre generate,inonlytwoweeks,toitsoriginalsize,after70%hepatectomy[2].Therefore,theresearchoncellu larandmole…     

Study of the mechanism of the photoisomerization and photooxidation of bilirubin using a model for the phototherapy of hyperbilirubinemia

Liquid chromatography was employed for a study of photochemical degradation of bilirubin in the complex with human albumin, using a model system in the presence of riboflavin. The concentrations of bilirubin, the photoisomers and biliverdin were monitored. The reaction mechanism was verified using a quantified mathematical model and was represented by a reaction scheme. Photoisomerization is the initial process, followed by photooxidation to degradation products of the tetrapyrrole skeleton, with formation of biliverdin as an intermediate. The blood of newborns that were irradiated for treatment of hyperbilirubinemia was studied for the sake of comparison. The effect of some biochemically important substances was followed, in view of possible inhibition of the processes. The experimental results demonstrate that riboflavin acts as a catalyst, even at the concentrations typical for its occurrence in blood. The results are discussed from the point of view of the mechanism of bilirubin degradation during phototherapy.     

Investigation of the ceriumIV oxidation of poly(vinyl alcohol)

Initiation of ceric ion-induced grafting from poly(vinyl alcohol) (PVOH) was studied by examining the formation and lifetime of colored complexes between cerium^IV and (1) a commercial PVOH, (2) a diol-free PVOH, and (3) several model 1,2-diols. UV/visible spectroscopy was employed using a wavelength of 520 nm. Results showed that the 1,2-diols, which are an inherent defect in PVOH, are the sites most reactive toward ceric ion. The observed rate constant for the reaction was found to increase with decreasing [Ce^IV] until the maximum rate was reached at which time reaction took place exclusively with 1,2-diols. The activation energy for oxidation of commercial PVOH at the maximum rate was 15.4 kcal/mol while that for diol-free PVOH was 22.4 kcal/mol. The 1,2-diols of PVOH displayed a high equilibrium constant for complexation with ceric ion, compared to the model 2,3-butanediol. It was suggested that the PVOH chain segments bring about crowding of the diol group, and this leads to a higher equilibrium constant for complexation. The lowest energy conformation of a PVOH chain segment containing a 1,2-diol linkage was calculated using the CHEMLAB-II molecular design program, and the 1,2-diol was predicted to be at the center of a sharp bend in the chain brought about by its presence.     

Application of ion-exchanger phase photoacoustic spectroscopy to flow analysis of trace amounts of iron in water

Ion-exchanger phase photoacoustic spectroscopy has been applied to the flow analysis of trace amounts of iron in water. The reaction product of iron(II) with 4,7-diphenyl-1,10-phenanthroline-disulphonate, introduced into a carrier solution stream in the flow system, was concentrated on a small amount of QAE-Sephadex gel settled in a fused silica glass tube (1.5 mm i.d.) of a photoacoustic cell. The photoacoustic signal produced by pulsed laser irradiation of the gel beads at 532 nm was detected by a cylindrical piezoelectric transducer which was attached outside the glass tube. When 3.7 ml of a sample solution was introduced into the flow system, the sensitivity of this method was 590 times higher than that of the corresponding solution photoacoustic spectrometry and the detection limit of iron was 0.33 ng/ml. Because the coloured complex was desorbed from the cell with a desorbing agent solution, the present method could afford repeated analyses of natural water samples containing iron at ng/ml levels without any preconcentration procedures.     

Role of hypaphorine in the toxicity of Astragalus lusitanicus

Hypaphorine, an alpha-N,N,N-trimethyltryptophan betaine, was isolated, for the first time, from Astragalus lusitanicus Lam. (Fabaceae), a plant highly toxic for lambs and goats. This alkaloid was characterized by NMR and MS analysis. Hypaphorine was previously reported to be a convulsive poison. To confirm the toxicity, it was synthesized and tested in goats. Hypaphorine was shown to be non-toxic for goats even at a high dose of 2 g kg(-1) by oral administration.     

Apparent increase of insulin peak area in HPLC analysis of a preparation consisting of a mixture of insulin and total parenteral nutrition

The peak area of insulin in a mixture of K.C.L. injection and hyperalimentation fluid was found to increase in a time dependent manner up to 24 h in measurement by a high-performance liquid chromatograph. The increase of peak area corresponding to the insulin was detected at wavelengths of both 210 and 280 nm. This increase was only observed in the presence of the sugars, tryptophan, riboflavin, and insulin, and ascorbate was shown to counteract the increase. These results suggest the possibility that insulin forms a mixture caused by the oxidation reaction in a hyperalimentation fluid.     

Microencapsulation of oil with poly(styrene-N,N-dimethylaminoethyl methacrylate) by SPG emulsification technique: effects of conversion and composition of oil phase

Microcapsules with narrow size distribution, in which hexadecane (HD) was used as a oily core and poly(styrene-co-N,N-dimethylaminoethyl methacrylate) [P(St-DMAEMA)] as a wall, were prepared by a Shirasu porous glass (SPG) emulsification technique and a subsequent suspension polymerization process. That is, a mixture of St monomer, DMAEMA monomer, HD, and N,N'-azobis(2,4-dimethylvaleronitrile) initiator was permeated through the uniform pores of an SPG membrane into a continuous phase containing a poly(vinylpyrrolidone), sodium lauryl sulfate, and sodium nitrite water-soluble inhibitor by applying a pressure, to form uniform droplets. Then, the droplets were polymerized at 70 degrees C. It was found that HD was encapsulated completely only when conversion was quite high, irrespective of whether a DMAEMA hydrophilic monomer was incorporated into the polymer. As the amount of HD increased, HD was more easily encapsulated by the polymer. In order to clarify the reason for such unique behavior, a simulation was carried out, taking the St monomer partition in the HD phase and PSt wall phase into the consideration. It was found that the main reason HD could not be encapsulated completely by PSt when conversion was lower was that the interfacial tension of the HD phase with water and the PSt phase with water got closer. As a result, both HD and PSt can come in contact with the water phase.     

Study of the mechanism of formation of transparent polyacrylonitrile

The kinetics of bulk polymerization of acrylonitrile, leading to a transparent polymer, was studied. The reaction was followed by a dilatometer specially designed for high degrees of conversion and for continuous supply of monomer during the reaction. The last stages of polymerization were followed by density determinations. It was found that the kinetic scheme did not show any irregularities, and that the major condition for obtaining a transparent polymer is a continuous supply of monomer to fill up the gaps formed by the contraction during the polymerization process.