SIMULTANEOUS DETERMINATION OF GUANINE, URIC-ACID, HYPOXANTHINE AND XANTHINE IN HUMAN PLASMA BY REVERSED-PHASE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH AMPEROMETRIC DETECTION

A reversed-phase high-performance liquid chromatographic method with amperometric detection is described for the separation and quantification of uric acid, guanine, hypoxanthine and xanthine. The isocratic separation of a standard mixture of the compounds was achieved in 5 min on a Spherisorb 5 C-18 reversed-phase column, with a mobile phase of NaH2PO4 (300 mmol dm(-3) pH 3.0)-methanol-acetonitrile-tetrahydrofuran (97.8 + 0.5 + 1.5 + 0.2). Uric acid, guanine, hypoxanthine and xanthine were completely separated, with detection limits in the range 2-20 pmol per injection. The effect of pH and the composition of the mobile phase on the separation are described. The hydrodynamic voltammograms of these compounds were recorded at a glassy carbon electrode. The linear range of the calibration graph for each compound was: uric acid; 1-5000 mu mol dm(-3); guanine, 0.5-2000 mu mol dm(-3); hypoxanthine, 0.1-500 mu mol dm(-3) and xanthine, 0.5-5000 mu mol dm(-3). The within- and between-day precision was good. The uric acid and hypoxanthine content in human plasma was measured using the proposed method. Good recoveries of uric acid (97.9-103%), hypoxanthine (98.0-99.2%), guanine (96.0-98.3%) and xanthine (96.0-102%) were obtained from human plasma. The results of electrochemical detection were in good agreement with those of UV detection.

SOLVENT-EXTRACTION OF SC(III), ZR(IV), TH(IV), FE(III), AND LU(III) WITH THIOSUBSTITUTED ORGANOPHOSPHINIC ACID EXTRACTANTS

The solvent extraction of Sc(III), Zr(IV), Th(IV), Fe(III) and Lu(III) with Cyanex 302 (bis(2,4,4-trimethylpentyl)monothiophosphinic acid) and Cyanex 301 ( bis(2,4,4-trimethylpentyl) dithiophosphinic acid) in n-hexane from acidic aqueous solutions has been investigated systematically. The effect of equilibrium aqueous acidity on the extraction with these reagents was studied. The separation of Th(IV), Fe(III) and Lu(III) from Sc(III), or the separation of other metals from Lu(III) with Cyanex 302, can be achieved by controlling the aqueous acidity. However, Cyanex 301 exhibited a poor selectivity for the above metals, except for Lu(III). The extraction of these metals with Cyanex 272, Cyanex 302 and Cyanex 301 has been compared. The stripping percentages of Sc(III) for Cyanex 302 and Cyanex 301 in a single stage are near 78% and 75% with 3.5 mol/L and 5.8 mol/L sulphuric acid solutions, respectively. The effects of extractant concentration and temperature on the extraction of Sc(III) were investigated. The stoichiometry of the extraction of Sc(III) with Cyanex 302 was determined. The role of different components of Cyanex 302 in the extraction of Sc(III) was discussed.

ELECTROCHEMICAL DETECTION OF COBALT IN HAIR FOLLOWING ON-COLUMN DERIVATIZATION WITH 1-(2-PYRIDYLAZO)-2-NAPHTHOL-6-SULFONIC ACID AND REVERSED-PHASE LIQUID-CHROMATOGRAPHY

A method for the specific determination of cobalt based on reversed-phase liquid chromatography with amperometric detection via on-column complex formation has been developed. A water-soluble chelating agent, 1-(2-pyridylazo)-2-naphthol-6-sulphonic acid (PAN-6S), is added to the mobile phase and aqueous cobalt solutions are injected directly into the column to form in situ the cobalt-PAN-6S chelate, which is then separated from other metal PAN-6S chelates and subjected to reductive amperometric detection at a moderate potential of -0.3 V. Because the procedure eliminates the interference of oxygen and depresses the electrochemical reduction of the mobile phase-containing ligand PAN-6S, by virtue of the quasi:reversible electrode process of the cobalt-PAN-6S complex, a low detection limit of 0.06 ng can be readily obtained. Interference effects were examined for sixteen common metal species, and at a 5- to 8000-fold excess by mass no obvious interference was observed. The feasibility of the method as an approach to the specific analysis of cobalt in a hair sample has been demonstrated.

THE PREPARATION OF ELECTRODES MODIFIED WITH ISOPOLYMOLYBDIC ACID PLUS POLYANILINE FILM AND ITS CATALYTIC EFFECTS ON CHLORATE IONS

Electrodes modified with isopolymolybdic acid+polyaniline film, which exhibit high stability and activity in aqueous acidic solution, have been prepared successfully using two methods: one-step synthesis by electrochemical polymerization at a constant applied potential of +0.80 V/SCE or by cycling the potential at 100 mV/s between -0.12 and +0.85 V in 0.5 M H2SO4 containing 5.0x10(-2) M aniline and 5.0x10(-3) M H4Mo8O26, or two-step synthesis by doping the polyaniline film electrode with isopoly acid (IPA) under a cycling potential between -0.20 and +0.40 V in 0.5 M H2SO4 containing the H4Mo8O26 dopant. The thickness of the film and the amount of dopant in the polyaniline film can be controlled by experimental parameters such as the charge, time and the ratio of aniline to IPA in the solution. The experimental results show that electrodes modified with isopolymolybdic acid+polyaniline film using both methods have a strong catalytic effect on the reduction of chlorate anions. Comparison of the two methods of modification shows that the catalytic effect at the modified electrode prepared by the two-step method is greater than that at the electrode prepared by the one-step method.

RADIATION GRAFT COPOLYMER OF ACRYLIC-ACID ONTO EVA

The structure of the radiation graft copolymer of acrylic acid onto EVA has been studied by infrared spectroscopy and XPS. It was found that along with the main peak C there is a photoelectron peak at 288.5 eV attributed to [GRAPHICS] group in XPS spectra and the content of its area in XPS increases with increasing of grafting degree of EVA. It was also found that hydrophilicity of EVA increases with the increase of grafting degree.

ELECTROCHEMICAL STUDY OF ISOPOLY-OXOMETALLATE AND HETEROPOLY-OXOMETALLATE FILM MODIFIED MICROELECTRODES .2. ELECTROCHEMICAL-BEHAVIOR OF ISOPOLYMOLYBDIC ACID MONOLAYER MODIFIED CARBON-FIBER MICROELECTRODES

In this paper the electrochemical properties of isopolymolybdic anion thin film modified carbon fibre (CF) microelectrode prepared by simple dip coating have been described. The modified electrode shows three couples of surface redox waves between + 0.70 and - 0.1 V vs. sce in 2 M H2SO4 solution with good stability and reversibility. The pH of solution has a marked effect on the electrochemical behaviour and stability of the film, the stronger the acidity of electrolyte solution is, the better the stability and reversibility of isopolymolybdic anion film CF microelectrode will be. The scanning potential range strongly influences on the electrochemical behaviour of the film. The isopolymolybdic anion film prepared by the dip coating resulting a monolayer with estimated surface concentration (F) 2.8 x 10(-11) mol cm-2. From the half-peak widths and peak areas of the surface redox waves of the film electrode, the first three surface waves are corresponding to two-electron processes. The electron energy spectra show the products by six electrons reduction are a mixture of Mo(VI) and Mo(V) species. The electrochemical reaction of the isopolymolybdic anion monolayer can be expressed as Mo8O264- + mH+ + 2ne half arrow right over half arrow left [HmMo8-2n(VI)Mo2n(V)O26](4,2n-m)-n = 1, 2, 3; m = 2, 5, 7.

CRYSTAL STRUCTURE AND THERMAL ANALYSIS OF ERBIUM COMPLEX WITH BENZENE ACETIC ACID

The crystal structure of erbium (III) complex of benzene acetic acid is reported. The complex crystallizes in the monoclinic space group P2(1)/a with a = 0,9008(3)nm, b=1.4242(5) nm, c=1.8437(7) nm, beta=98.80(3)degrees, V = 2.337(1) nm(3), Z = 4. The mechanism of thermal decomposition of complex has been studied by TG-DTG-DTA. The activation energy for dehydration reaction has been calculated by Freeman Carroll method. The enthalpy change for dehydration and phase change process has been determined.

ELECTROCATALYTIC OXIDATION OF ASCORBIC ACID AT POLYANILINE FILM MODIFIED GLASSY CARBON ELECTRODES

A conducting polyaniline (PAn) film modified glassy carbon (GC) electrode was prepared by electrochemical polymerization. The electrochemical behavior of ascorbic acid (AH(2)) in aqueous solution at this PAn modified electrode was studied in detail. The experimental results show that PAn film modified electrode has good electrocatalytic activity on the oxidation of ascorbic acid in aqueous solution over a wide range of pH value, among which pH 4 is the optimum condition. The oxidation process of ascorbic acid at PAn film electrode can be regarded as an EC catalytic mechanism. The kinetic process of the catalytic reaction was investigated by rotating disk electrode (RDE) coated with PAn films. The rate constant of the catalytic reaction was evaluated. The catalytic peak currents are proportional to the concentrations tions of ascorbic acid in the range of 5 x 10(-2)-1 x 10(-6) mol . L-1. The PAn film elec trodes give very stable responce for the oxidation of ascorbic acid. The present investigation shows the posibility of using PAn film modified electrode for the determination of ascorbic acid.

SYNTHESIS AND VIBRATIONAL SPECTRUM STUDIES OF RARE EARTH COMPLEXES WITH CYCLOHEXANE CARBOXYLIC ACID

The solid state complexes of trivalent lanthanid, yttrium and scandium with cyclohexane carboxylic acid have been isolated and characterized by IR and Raman spectroscopy. It was found that there are only chelated carboxylate groups in the scandium complex and that there are the chelated, bridged and chelate-bridged carboxylate groups in other rare earth complexes. The former is a mononuclear complex and the latter is a polynuclear polymer. The RE—O coordinate bonds possess the characters of convalent ionic ...

Molecular cloning and stress-dependent expression of a gene encoding Delta(12)-fatty acid desaturase in the Antarctic microalga Chlorella vulgaris NJ-7

The psychrotrophic Antarctic alga, Chlorella vulgaris NJ-7, grows under an extreme environment of low temperature and high salinity. In an effort to better understand the correlation between fatty acid metabolism and acclimation to Antarctic environment, we analyzed its fatty acid compositions. An extremely high amount of Delta(12) unsaturated fatty acids was identified which prompted us to speculate about the involvement of Delta(12) fatty acid desaturase in the process of acclimation. A full-length cDNA sequence, designated CvFAD2, was isolated from C. vulgaris NJ-7 via reverse transcription polymerase chain reaction (RT-PCR) and RACE methods. Sequence alignment and phylogenetic analysis showed that the gene was homologous to known microsomal Delta(12)-FADs with the conserved histidine motifs. Heterologous expression in yeast was used to confirm the regioselectivity and the function of CvFAD2. Linoleic acid (18:2), normally not present in wild-type yeast cells, was detected in transformants of CvFAD2. The induction of CvFAD2 at an mRNA level under cold stress and high salinity is detected by real-time PCR. The results showed that both temperature and salinity motivated the upregulation of CvFAD2 expression. The accumulation of CvFAD2 increased 2.2-fold at 15A degrees C and 3.9-fold at 4A degrees C compared to the alga at 25A degrees C. Meanwhile a 1.7- and 8.5-fold increase at 3 and 6% NaCl was detected. These data suggest that CvFAD2 is the enzyme responsible for the Delta(12) fatty acids desaturation involved in the adaption to cold and high salinity for Antarctic C. vugaris NJ-7.

Programmed cell death in Laminaria japonica (Phaeophyta) tissues infected with alginic acid decomposing bacterium

TdT-mediated dUTP-biotin nick end labeling (TUNEL) is a sensitive and valid method for detecting DNA cleavage in programmed cell death (PCD). Using this method, DNA cleavage was observed in Laminaria japonica sporophytic tissues, which were infected with alginic acid decomposing bacterium. It was found that DNA cleavage occurred 5 min after the infection, the fragments with 3'-OH groups of cleaved nuclear DNA increased with time of infection and spread from the infection site. Although no typical DNA ladder (200 bp/ 180 bp) was detected by routine agarose gel electrophoresis, the cleavage of nuclear DNA fragments of 97 similar to 48.5 kb could be detected by pulsed field gel electrophoresis (PFGE). By using CaspGLOW(TM) fluorescein active caspase-3 staining method, caspase-3 activity has been detected in response to the infection of alginic acid decomposing bacterium. Our results are similar to the observations in hypersensitive response (HR) of higher plant, suggesting that the rapid cell death of L. japonica infected by alginic acid decomposing bacterium might be involved in PCD, and indicating that the occurrence of PCD is an active defense process against the pathogen's infection.

The complete amino acid sequence of growth hormone and partial amino acid sequence of prolactin and somatolactin from sea perch (Lateolabrax japonicus)

Growth hormone (GH), prolactin (PRL) and somatolactin (SL) were purified simultaneously under alkaline condition (pH 9.0) from pituitary glands of sea perch (Lateolabrax japonicas) by a two-step procedure involving gel filtration on Sephadex G-100 and reverse-phase high-performance liquid chromatography (rpHPLC). At each step of purification, fractions were monitored by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and by immunoblotting with chum salmon GH. PRL and SL antisera. The yields of sea perch GH, PRL and SL were 4.2, 1.0 and 0.28 mg/g wet tissue, respectively. The molecular weights of 19,200 and 20,370 Da were estimated by SDS-PAGE for sea perch GH and PRL, respectively. Two forms of sea perch SL were found: one (28,400 Da) is probably glycosylated, while the other one (23,200 Da) is believed to be deglycosylated. GH bioactivity was examined by an in vivo assay. Intraperitoneal injection of sea perch GH at a dose of 0.01 and 0.1 mug/g body weight at 7-day intervals resulted in a significant increase in body weight and length of juvenile rainbow trout. The complete sea-perch GH amino acid sequence of 187 residues was determined by sequencing fragments cleaved by chemicals and enzymes. Alignment of sea-perch GH with those of other fish GHs revealed that sea-perch GH is most similar to advanced marine fish, such as tuna, gilthead sea bream, yellowfin porgy, red sea bream, bonito and yellow tail with 98.4, 96.2%, 95.7%, 95.2%, 94.1% and 91% sequence identity, respectively. Sea-perch GH has low identity to Atlantic cod (76.5%), hardtail (73.3%), flounder (68.4%), chum salmon (66.3%), carp (54%) and blue shark (38%). Partial amino-acid sequences of 127 of sea-perch PRL and the N-terminal of 16 amino-acid sequence of sea-perch SL have been determined. The data show that sea-perch PRL has a slightly higher sequence identity with tilapia PRL( 73.2%) than with chum salmon PRL(70%) in this 127 amino-acid sequence. (C) 2001 Elsevier Science B.V. All rights reserved.

Diet-induced changes in lipid and fatty acid composition of Artemia salina

The influence of diet on lipid and fatty acid composition of the brine shrimp Artemia salina nauplii was investigated. Various diets with different lipid composition and fatty acid profiles were fed to nauplii for 2 weeks. The lipid composition of microalgal diets, Isochrysis galbana, Phaeodactylum tricornutum and Nannochloropsis oculata and baker's yeast was analyzed. Newly hatched nauplii were examined before the feeding experiment. It was shown that Artemia was able to incorporate and selectively concentrate some dietary lipids. Depot lipids were more sensitive to changes in the dietary lipid composition than the main structural lipids, polar lipids and sterols. Variations in the content of the lipid classes correlated with stage of development of the animal. The fatty acid composition of the animal varied with that of diet. The concentrations of saturated fatty acids were apparently supported in the nauplii by biosynthesis de novo. The acid 16:1(n-7) originated from the food. The concentration range of n-6 polyunsaturated fatty acids (PUFAs) remained constant through the accumulation from the diet. The proportion of n-3 PUFAs varied with their level in the diet. The dynamics of alteration of 20:5(n-3) content in Artemia fed on Isochrysis, which is poor in this acid, suggested a limited capacity for elongation and desaturation of 18:3(n-3) to 20:5(n-3). None of the diets provided dietary input of 22:6(n-3). (C) 1998 Elsevier Science Inc. All rights reserved.

5,7-Dihydroxy-5,6,7,8-tetrahydro-1H-azocin-2-one from a marine-derived Streptomyces sp.

In the course of a screening program, we have isolated the new natural product, 5,7-dihydroxy-5,6,7,8-tetrahydroazocin-2(IH)-one (1), from the staurosporine producing marine-derived Streptomyces sp. strain QD518. Here we report the isolation and structure elucidation of 1 and the artifacts 3 and 4 resulting from I by acid catalyzed intra- and inter-molecular reactions.

Cflec-5, a pattern recognition receptor in scallop Chlamys farreri agglutinating yeast Pichia pastoris

C-type lectins are a superfamily of carbohydrate-recognition proteins which play crucial roles as pattern recognition receptors (PRRs) in the innate immunity. In this study, the full-length cDNA of a C-type lectin was cloned from scallop Chlamys farreri (designated as Cflec-5) by expression sequence tag (EST) analysis and rapid amplification of cDNA ends (RACE) approach The full-length cDNA of Cflec-5 was of 1412 bp. The open reading frame encoded a polypeptide of 153 amino acids, including a signal sequence and a conserved carbohydrate-recognition domain with the EPN motif determining the mannose-binding specificity The deduced amino acid sequence of Cflec-5 showed high similarity to members of C-type lectin superfamily. The quantitative real-time PCR was performed to investigate the tissue distribution of Cflec-5 mRNA and its temporal expression profiles in hemocytes post pathogen-associated molecular patterns (PAMPs) stimulation. In healthy scallops, the Cflec-5 mRNA was mainly detected in gill and mantle, and marginally in other tissues The mRNA expression of Cflec-5 could be significantly induced by lipopolysaccharide (LPS) and glucan stimulation and reached the maximum level at 6 h and 12 h, respectively But its expression level did not change significantly during peptidoglycan (PGN) stimulation The function of Cflec-5 was investigated by recombination and expression of the cDNA fragment encoding its mature peptide in Escherichia coli Rosetta Gami (DE3) The recombinant Cflec-5 agglutinated Pichia pastoris in a calcium-independent way The agglutinating activity could be inhibited by D-mannose. LPS and glucan, but not by D-galactose or PGN. These results collectively suggested that Cflec-5 was involved in the innate Immune response of scallops and might contribute to nonself-recognition through its interaction with various PAMPs (C) 2010 Elsevier Ltd All rights reserved