WorldWideScience

Sample records for aminoethanethiol

  1. EST Table: FS904141 [KAIKOcDNA[Archive

    Lifescience Database Archive (English)

    Full Text Available ar to 2-aminoethanethiol (cysteamine) dioxygenase [Tribolium castaneum] gb|EFA09634.1| hypothetical protein ...10 33 %/248 aa gnl|Amel|GB12350-PA 10/09/10 35 %/238 aa gi|91090992|ref|XP_974899.1| PREDICTED: similar to 2-aminoethanethiol (cystea

  2. EST Table: FY036659 [KAIKOcDNA[Archive

    Lifescience Database Archive (English)

    Full Text Available FY036659 rbmte13c09 11/12/09 GO hit GO:0047800(cysteamine dioxygenase activity)|GO:...f|XP_974899.1| PREDICTED: similar to 2-aminoethanethiol (cysteamine) dioxygenase [Tribolium castaneum] FY036659 bmte ...

  3. Cyclic Voltammetric Responses of Nitrate Reductase on Chemical Modified Electrodes

    Institute of Scientific and Technical Information of China (English)

    YaRuSONG; HuiBoSHAO; 等

    2002-01-01

    Electrochemistry of nitrate reductases (NR) incorporated into 2-aminoethanethiol self-assembled on the gold electrode and polyacrylamide cast on the pyrolytic graphite electrode was examined. NR on chemical modified electrode showed electrochemical cyclic voltammetric responses in phosphate buffers.

  4. Analysis of VX nerve agent hydrolysis products in wastewater effluents by ion chromatography with amperometric and conductivity detection.

    Science.gov (United States)

    Piao, Haishan; Marx, Randall B; Schneider, Steven; Irvine, David A; Staton, John

    2005-09-30

    An analytical method, based on the use of ion chromatography, was developed to monitor the levels of three regulated VX hydrolysis products in the effluent from a biological wastewater treatment process--ethylmethylphosphonic acid, methylphosphonic acid and 2-(diisopropyl)aminoethanethiol. Previous methods have not been applied to wastewater matrices or 2-(diisopropyl)aminoethanethiol. Despite the specificity and sensitivity constraints of this method, it was possible to measure the compounds in bioreactor effluents down to a level substantially below the US Army discharge limit of 0.1% (w/v). Analytical data was confirmed by liquid chromatography-mass spectrometry (LC-MS) at an independent laboratory.

  5. EST Table: FS920530 [KAIKOcDNA[Archive

    Lifescience Database Archive (English)

    Full Text Available FS920530 E_FL_fufe_50K23_F_0 11/12/09 GO hit GO:0047800(cysteamine dioxygenase acti...090992|ref|XP_974899.1| PREDICTED: similar to 2-aminoethanethiol (cysteamine) dioxygenase [Tribolium castaneum] FS920530 fufe ...

  6. A fluorescent-labeled microcystin-LR terbium cryptate

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Eduardo J.A. [Centro Federal de Educacao Tecnologica de Pernambuco, Recife, PE (Brazil)]. E-mail: edualec@oi.com.br; Vila Nova, Suzana P.; Alves-Junior, Severino; Santa-Cruz, Petrus [Pernambuco Univ., Recife, PE (Brazil). Dept. de Quimica Fundamental; Molica, Renato J.R. [Associacao Instituto de Tecnologia de Pernambuco, Recife, PE (Brazil); Teixeira, Antonio [Brasilia Univ., DF (Brazil). Faculdade de Medicina; Malageno, Elizabete; Lima Filho, Jose L. [Pernambuco Univ., Recife, PE (Brazil). Lab. de Imunopatologia Keizo Asami

    2006-03-15

    A new fluorescent labeled compound of microcystin-LR with terbium cryptate was obtained by initial conjugation of microcystins-LR with aminoethanethiol followed by the reaction with the ester group of terbium cryptate. The product formation was followed by high performance liquid chromatography (HPLC) at 238 nm and 310 nm. The presence of microcystin-LR in the labeled molecule was confirmed by enzyme linked immunosorbent assay ELISA and by protein reaction with bicinhonic acid. Luminescence spectra of cryptate and the conjugated molecule were carried through as well. (author)

  7. Singlet oxygen generation from water-soluble quantum dot-organic dye nanocomposites.

    Science.gov (United States)

    Shi, Lixin; Hernandez, Billy; Selke, Matthias

    2006-05-17

    Water-soluble quantum dot-organic dye nanocomposites have been prepared via electrostatic interaction. We used CdTe quantum dots with diameters up to 3.4 nm, 2-aminoethanethiol as a stabilizer, and meso-tetra(4-sulfonatophenyl)porphine dihydrochloride (TSPP) as an organic dye. The photophysical properties of the nanocomposite have been investigated. The fluorescence of the parent CdTe quantum dot is largely suppressed. Instead, indirect excitation of the TSPP moiety leads to production of singlet oxygen with a quantum yield of 0.43. The nanocomposite is sufficiently photostable for biological applications.

  8. Direct 99mTc labeling of monoclonal antibodies: radiolabeling and in vitro stability.

    Science.gov (United States)

    Garron, J Y; Moinereau, M; Pasqualini, R; Saccavini, J C

    1991-01-01

    Direct labeling involves 99mTc binding to different donor groups on the protein, giving multiple binding sites of various affinities resulting in an in vivo instability. The stability has been considerably improved by activating the antibody using a controlled reduction reaction (using 2-aminoethanethiol). This reaction generates sulfhydryl groups, which are known to strongly bind 99mTc. The direct 99mTc antibody labeling method was explored using whole antibodies and fragments. Analytical methods were developed for routine evaluation of radiolabeling yield and in vitro stability. Stable direct antibody labeling with 99mTc requires the generation of sulfhydryl groups, which show high affinity binding sites for 99mTc. Such groups are obtained with 2-aminoethanethiol (AET), which induces the reduction of the intrachain or interchain disulfide bond, with no structural deterioration or any loss of immunobiological activity of the antibody. The development of fast, reliable analytical methods has made possible the qualitative and quantitative assessment of technetium species generated by the radiolabeling process. Labeling stability is determined by competition of the 99mTc-antibody bond with three ligands, Chelex 100 (a metal chelate-type resin), free DTPA solution and 1% HSA solution. Very good 99mTc-antibody stability is obtained with activated IgG (IgGa) and Fab' fragment, which makes these substances possible candidates for immunoscintigraphy use.

  9. Potential control of DNA self-assembly on gold electrode

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The self-assembly monolayer (SAM) was prepared with 2-aminoethanethiol (AET) on the gold electrode.A new approach based on potential was first used to control DNA self-assembly covalently onto the SAM with the activation of 1-ethyl-3(3-dimethylaminopropyl)-carbodiimide (EDC) and N-hydroxysulfosuccinimide (NHS). The influence of potential on DNA self-assembly was investigated by means of cyclic voltammetry (CV), AC impedance, Auger electron spectrometry (AES) and atomic force microscopy (AFM). The result proves that controlled potential can affect the course of DNA self-assembly. More negative potential can restrain the DNA self-assembly, while more positive potential can accelerate the DNA self-assembly, which is of great significance for the control of DNA self-assembly and will find wide application in the field of DNA-based devices.

  10. Potential control of horseradish peroxidase immobilization on gold electrode

    Institute of Scientific and Technical Information of China (English)

    GE; Cunwang; YU; Wei; LI; Changan; WANG; Nanping; GU; Ning

    2004-01-01

    A new approach based on potential control was firstly used for the immobilization of horseradish peroxidase (HRP) as the model protein. The self-assembly monolayer (SAM) was prepared with 2-aminoethanethiol (AET) on the gold electrode. The charge on HRP was adjusted by means of the acidity of the phosphate buffer solution (PBS) for dissolving the HRP. The influence of electric potential on HRP immobilization was investigated by means of colorimetric immunoassay of enzyme-substrate interaction (CIESI) using an automatic plate reader. The HRP modified electrodes were characterized with X-ray photoelectron spectroscopy (XPS) as well as atomic force microscope (AFM) on template-stripped gold surface. The potential for maximum immobilization of HRP was near the zero charge potential. The result indicates that controlled potential can affect the course of HRP immobilization without the loss of enzymic activity. It is of great significance for the control of biomolecular self-assembly and the intrinsic electric device.

  11. From N-vinylpyrrolidone anions to modified paraffin-like oligomers via double alkylation with 1,8-dibromooctane: access to covalent networks and oligomeric amines for dye attachment

    Science.gov (United States)

    Obels, Daniela; Lievenbrück, Melanie

    2016-01-01

    Summary The double alkylation of N-vinylpyrrolidone (N-VP) with 1,8-dibromooctane yields paraffin-like oligomeric chains bearing polymerizable vinyl moieties. These oligomers were radically crosslinked in bulk with N-VP as co-monomer yielding swellable polymer disks. The vinylic side groups of the N-VP oligomers allow thiol–ene click reactions with 2-aminoethanethiol hydrochloride to obtain reactive amino-functionalized oligomers. Further modification of the free amino groups with 1,4-difluoro-9,10-anthraquinone (DFA) yields red-colored oligomeric anthraquinone dyes. The final reaction of DFA-substituted N-VP oligomers with Jeffamine® M 600 leads to blue-colored and branched oligomers with poly(ethylene glycol) side chains. PMID:27559389

  12. Deposition of gold nanoparticles onto thiol-functionalized multiwalled carbon nanotubes.

    Science.gov (United States)

    Zanella, Rodolfo; Basiuk, Elena V; Santiago, Patricia; Basiuk, Vladimir A; Mireles, Edgar; Puente-Lee, Iván; Saniger, José M

    2005-09-01

    Gold nanoparticles were deposited on the surface of multiwalled carbon nanotubes (MWNTs) functionalized with aliphatic bifunctional thiols (1,4-butanedithiol, 1,6-hexanedithiol, 1,8-octanedithiol, and 2-aminoethanethiol) through a direct solvent-free procedure. Small gold particles, with a narrow particle size distribution around 1.7 nm, were obtained on 1,6-hexanedithiol-functionalized MWNTs. For MWNTs functionalized with the aminothiol, the average Au particle size was larger, 5.5 nm, apparently due to a coalescence phenomenon. Gatan image filter (GIF) observations show that sulfur is at the nanotube surface with a non-homogeneous distribution. A higher sulfur concentration was observed around the gold nanoparticles' location.

  13. Ultrasonic-assisted self-assembly of monolayer graphene oxide for rapid detection of Escherichia coli bacteria

    Science.gov (United States)

    Chang, Jingbo; Mao, Shun; Zhang, Yang; Cui, Shumao; Zhou, Guihua; Wu, Xiaogang; Yang, Ching-Hong; Chen, Junhong

    2013-04-01

    Due to potential risks to the environment and human health arising from pathogens/chemical contaminants, novel devices are being developed for rapid and precise detection of those contaminants. Here, we demonstrate highly sensitive and selective field-effect transistor (FET) sensor devices for detection of Escherichia coli (E. coli) bacteria using thermally reduced monolayer graphene oxide (TRMGO) sheets as semiconducting channels. The graphene oxide (GO) sheets are assembled on the aminoethanethiol (AET)-functionalized gold (Au) electrodes through electrostatic interactions with ultrasonic assistance. Anti-Escherichia coli (anti-E. coli) antibodies are used as receptors for selective detection of E. coli cells and integrated on the FET device through covalent bonding with Au nanoparticles on the GO surface. The TRMGO FET device shows great electronic stability and high sensitivity to E. coli cells with a concentration as low as 10 colony-forming units (cfu) per mL. The biosensing platform reported here is promising for large-scale, sensitive, selective, low-cost, and real-time detection of E. coli bacteria.

  14. Ultrahigh capacity anode material for lithium ion battery based on rod gold nanoparticles decorated reduced graphene oxide

    Energy Technology Data Exchange (ETDEWEB)

    Atar, Necip, E-mail: necipatar@gmail.com [Department of Chemical Engineering, Pamukkale University, Denizli (Turkey); Eren, Tanju [Department of Chemical Engineering, Pamukkale University, Denizli (Turkey); Yola, Mehmet Lütfi [Department of Metallurgical and Materials Engineering, Sinop University, Sinop (Turkey)

    2015-09-01

    In this study, we report the synthesis of rod shaped gold nanoparticles/2-aminoethanethiol functionalized reduced graphene oxide composite (rdAuNPs/AETrGO) and its application as an anode material for lithium-ion batteries. The structure of the rdAuNPs/AETrGO composite was characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction. The electrochemical performance was investigated at different current rates by using a coin-type cell. It was found that the rod shaped gold nanoparticles were highly dispersed on the reduced graphene oxide sheets. Moreover, the rdAuNPs/AETrGO composite showed a high specific gravimetric capacity of about 1320 mAh g{sup −1} and a long-term cycle stability. - Highlights: • We prepared rod shaped gold nanoparticles functionalized reduced graphene oxide. • The nanocomposite was used as an anode material for lithium-ion batteries. • The nanocomposite showed a high specific gravimetric capacity of about 1320 mAh g{sup −1}. • The nanocomposite exhibited a long-term cycle stability.

  15. Three salts from the reactions of cysteamine and cystamine with L-(+)-tartaric acid.

    Science.gov (United States)

    Benylles, Amina; Cairns, Donald; Cox, Philip J; Kay, Graeme

    2013-06-01

    Reaction between cysteamine (systematic name: 2-aminoethanethiol, C2H7NS) and L-(+)-tartaric acid [systematic name: (2R,3R)-2,3-dihydroxybutanedioic acid, C4H6O6] results in a mixture of cysteamine tartrate(1-) monohydrate, C2H8NS(+)·C4H5O6(-)·H2O, (I), and cystamine bis[tartrate(1-)] dihydrate, C4H14N2S2(2+)·2C4H5O6(-)·2H2O, (III). Cystamine [systematic name: 2,2'-dithiobis(ethylamine), C4H12N2S2], reacts with L-(+)-tartaric acid to produce a mixture of cystamine tartrate(2-), C4H14N2S2(2+)·C4H4O6(2-), (II), and (III). In each crystal structure, the anions are linked by O-H···O hydrogen bonds that run parallel to the a axis. In addition, hydrogen bonding involving protonated amino groups in all three salts, and water molecules in (I) and (III), leads to extensive three-dimensional hydrogen-bonding networks. All three salts crystallize in the orthorhombic space group P2(1)2(1)2(1).

  16. Insights into the surface and redox properties of single-walled carbon nanotube-cobalt(II) tetra-aminophthalocyanine self-assembled on gold electrode

    Energy Technology Data Exchange (ETDEWEB)

    Ozoemena, Kenneth I. [Chemistry Department, University of Pretoria, Pretoria 0002 (South Africa)]. E-mail: kenneth.ozoemena@up.ac.za; Nyokong, Tebello [Chemistry Department, Rhodes University, Grahamstown 6140 (South Africa); Nkosi, Duduzile [Chemistry Department, University of Pretoria, Pretoria 0002 (South Africa); Chambrier, Isabelle [School of Chemical Sciences and Pharmacy, University of East Anglia, Norwich, Norfolk NR4 7TJ (United Kingdom); Cook, Michael J. [School of Chemical Sciences and Pharmacy, University of East Anglia, Norwich, Norfolk NR4 7TJ (United Kingdom)

    2007-03-10

    This paper describes for the first time the electrochemical properties of redox-active self-assembled films of single-walled carbon nanotubes (SWCNTs) coordinated to cobalt(II)tetra-aminophthalocyanine (CoTAPc) by sequential self-assembly onto a preformed aminoethanethiol (AET) self-assembled monolayer (SAM) on a gold electrode. Both redox-active SAMs (Au-AET-SWCNT and Au-AET-SWCNT-CoTAPc) exhibited reversible electrochemistry in aqueous (phosphate buffer) solution. X-ray photoelectron spectroscopy (XPS) confirmed the appearance on the gold surface of the various elements found on the SAMs. Atomic force microscopy (AFM) images prove, corroborating the estimated electrochemical surface concentrations, that these SAMs lie normal to the gold surface. Electrochemical impedance spectroscopy (EIS) analyses in the presence of [Fe(CN){sub 6}]{sup 3-/4-} as a redox probe revealed that the Au-AET-SWCNT-CoTAPc showed much lower ({approx}10 times) electron-transfer resistance (R {sub et}) and much higher ({approx}10 times) apparent electron-transfer rate constant (k {sub app}) compared to the Au-AET-SWCNT SAM. Interestingly, a preliminary electrocatalytic investigation showed that both SAMs exhibit comparable electrocatalytic responses towards the detection of dopamine in pH 7.4 phosphate buffer solutions (PBS). The electrochemical studies (cyclic voltammetry (CV) and EIS) prove that SWCNT greatly improves the electronic communication between CoTAPc and the Au electrode surface.

  17. MnO_2纳米溶胶-甲醛化学发光体系及其分析应用研究%Chemiluminescence of Nano-Colloidal MnO2 with Formaldehyde and Its Analytical Application

    Institute of Scientific and Technical Information of China (English)

    杜建修; 王虹

    2012-01-01

    Water-soluble forms of colloidal MnO2 were prepared by the chemical reduction of KMnO4 with Na2S203 under neutral aqueous condition. The as-prepared colloidal MnO2 solution is dark-brown, trans- parent, stable, and possesses the maximum absorption peak at 375 nm and an average diameter of 40 nm. The as-prepared nano-colloidal MnO2 was found to react with formaldehyde to generate weak chemiluminescence (CL) under acidic condition. The effects of more than 30 pharmaceuticals on the nancolloidal MnO2-formaldehyde CL system were tested. Pharmaceuticals including phenothiazines and aminoethanethiols were observed to enhance the CL signal significantly. The experimental conditions were well optimized and the analytical figures for five phenothiazines and four aminoethanethiols were presented. The method was validated by the analysis of perphenazine in tablets and chlorpromazine hydrochloride in swine feed. The CL reaction mechanism was discussed by the study of CL spectra, fluorescence spectra, UV-vis absorption spectra, and other experiments. All of CL reactions had the same maximum emission wavelength about 640 nm, which suggested that the CL emitter was independent of analytes. The CL signal was inhibited obviously by single-state oxygen scavengers, sodium azide and 1,4-diazabicyclo[2,2,2]octane, indicating that single-state oxygen dimer was the potential CL emitter for the present CL reaction.%Na2S2O3在中性水溶液中还原KMnO4可制备得到暗棕色的可溶性MnO2溶胶.所制备的MnO2溶胶透明、稳定,最大吸收波长位于357 nm处,平均粒径约40 nm.研究发现,所制备的MnO2纳米溶胶在酸性介质中与甲醛反应可产生弱的化学发光.考察了近30种药物分子在MnO2纳米溶胶-甲醛体系中的化学发光行为.结果表明,吩噻嗪类药物、氨基硫醇类药物等对该体系的化学发光信号具有显著的增强作用.据此,建立了利用这一化学发光体系测定五种吩噻嗪类药物和四种氨基

  18. Application of disorganized monolayer films on gold electrodes to the prevention of surfactant inhibition of the voltammetric detection of trace metals via anodic stripping of underpotential deposits: detection of copper.

    Science.gov (United States)

    Herzog, Grégoire; Arrigan, Damien W M

    2003-01-15

    Development of an approach to prevention of electrode surface fouling by surfactants in samples is demonstrated. Spontaneously adsorbed monolayer systems employing short alkyl chains and bulky end groups are used to form porous disorganized monolayers on gold electrodes. Detection of copper by stripping of underpotential deposits formed at electrodes modified with disorganized films of mercaptoethanesulfonate (MES), mercaptopropanesulfonate, mercaptoacetic acid, and mercaptopropanoic acid was possible, and to a much lesser extent at aminoethanethiol and L-cysteine films. Use of short deposition times in conjunction with linear sweep anodic stripping voltammetry allowed detection of Cu2+ ions down to 1 x 10(-6) M in sulfuric acid solution, using underpotential deposition as the deposition step of the procedure. Calibration graphs were linear in the concentration range (1-80) x 10(-6) M Cu2+ using 15-s deposition at 0.00 V versus Ag/AgCl. The surfactants Tween 20, Tween 80, and Triton X-100 were found to have no affect on detection of Cu2+ ions in the calibration curve concentration range using MES-modified gold electrodes, whereas at unmodified gold electrodes very severe attenuation of the detection capability was manifested. The average slope for all calibration curves at the MES-modified electrode in the absence and presence of the surfactants at two different concentration levels was 0.0710 +/- 0.0024 microA microM(-1); in contrast, the slope of the calibration line at uncoated gold electrodes in the presence of surfactant was 0.0268 microA microM(-1). These results indicate the excellent ability of a disorganized, porous monolayer for prevention of fouling of the electrode surface by the surfactants.

  19. Rhemium-186-monoaminemonoamidedithiol-conjugated bisphosphonate derivatives for bone pain palliation

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, Kazuma [Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto 606-8501 (Japan); Advanced Science Research Center, Kanazawa University, Kanazawa 920-8640 (Japan); Mukai, Takahiro [Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto 606-8501 (Japan); Graduate School of Pharmaceutical Sciences, Kyushu University, Higashi-ku, Fukuoka 812-8582 (Japan); Arano, Yasushi [Graduate School of Pharmaceutical Sciences, Chiba University, Chuo-ku, Chiba 260-8675 (Japan); Otaka, Akira [Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto 606-8501 (Japan); Ueda, Masashi [Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto 606-8501 (Japan); Uehara, Tomoya [Graduate School of Pharmaceutical Sciences, Chiba University, Chuo-ku, Chiba 260-8675 (Japan); Magata, Yasuhiro [Photon Medical Research Center, Hamamatsu University School of Medicine, Hamamatsu 431-3192 (Japan); Hashimoto, Kazuyuki [Japan Atomic Energy Research Institute, Tokai-mura, Ibaraki 319-1195 (Japan); Saji, Hideo [Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto 606-8501 (Japan)]. E-mail: hsaji@pharm.kyoto-u.ac.jp

    2006-05-15

    To develop a radiopharmaceutical for the palliation of painful bone metastases based on the concept of bifunctional radiopharmaceuticals, we synthesized a bisphosphonate derivative labeled with rhenium-186 ({sup 186}Re) that contains a hydroxyl group at the central carbon of its bisphosphonate structure, we attached a stable {sup 186}Re-MAMA chelate to the amino group of a 4-amino butylidene-bisphosphonate derivative [N-[2-[[4-[(4-hydroxy-4,4-diphosphonobutyl)amino]-4-oxobutyl] -2-thioethylamino]acetyl]-2-aminoethanethiolate] oxorhenium (V) ({sup 186}Re-MAMA-HBP) and we investigated the effect of a hydroxyl group at the central carbon of its bisphosphonate structure on affinity for hydroxyapatite and on biodistribution by conducting a comparative study with [N-[2-[[3-(3,3-diphosphonopropylcarbamoyl)propyl]-2-thioethylamino]acetyl] -2-a minoethanethiolate] oxorhenium (V) ({sup 186}Re-MAMA-BP). The precursor of {sup 186}Re-MAMA-HBP, trityl (Tr)-MAMA-HBP, was obtained by coupling a Tr-MAMA derivative to 4-amino-1-hydroxybutylidene-1,1-bisphosphonate. {sup 186}Re-MAMA-HBP was prepared by a reaction with {sup 186}ReO{sub 4} {sup -} and SnCl{sub 2} in citrate buffer after the deprotection of the Tr groups of Tr-MAMA-HBP. After reversed-phase high-performance liquid chromatography, {sup 186}Re-MAMA-HBP had a radiochemical purity of over 95%. Compared with {sup 186}Re-MAMA-BP, {sup 186}Re-MAMA-HBP showed a greater affinity for hydroxyapatite beads in vitro and accumulated a significantly higher level in the femur in vivo. Thus, the introduction of a hydroxyl group into {sup 186}Re complex-conjugated bisphosphonates would be effective in enhancing accumulation in bones. These findings provide useful information on the design of bone-seeking therapeutic radiopharmaceuticals.

  20. Cysteamine-induced reduction in gastrointestinal somatostatin: evidence for a region-specific loss in immunoreactivity.

    Science.gov (United States)

    McIntosh, C H; Bakich, V; Bokenfohr, K; DiScala-Guenot, D; Kwok, Y N; Brown, J C

    1988-06-01

    Administration of cysteamine (beta-mercaptoethylamine; 2-aminoethanethiol) to rats has been shown to decrease the levels of somatostatin-like immunoreactivity (SLI) in the gastrointestinal tract and pancreas but its mode of action is unclear. In the current study the effect of cysteamine on gastrointestinal and pancreatic SLI has been studied using two antisera with different regional specificities. In addition, the in vitro effect of cysteamine on SS-14 and SS-28 has been studied by high-performance liquid chromatography (HPLC). Characterization of the two antisera (AS 26.3.2 and AS 1001) with a range of analogs of SS-14 revealed that both were directed against the midportion of the molecule but that AS 1001 was also sensitive to changes at the N- and C-termini. Tissue extracts from cysteamine-treated rats measured with AS 26.3.2 showed no significant change for the stomach, jejunum or pancreas but duodenal levels were reduced. With AS 1001 SLI levels were reduced in all tissues. Gel permeation chromatography of stomach extracts measured with AS 1001 showed a reduction in both SS-14 and SS-28. With AS 26.3.2 an increase in SLI eluting prior to the SS-14 peak occurred explaining why no significant reduction in total SLI was detected. With duodenal extracts the elution profiles with AS 1001 reflected the large reduction in total SLI whereas with AS 26.3.2 a smaller reduction occurred. Both SS-14 and SS-28 were reduced. HPLC analysis of SS-14 and SS-28 following incubation with cysteamine in vitro showed a time-dependent decrease in both somatostatin species with absorbance at 280 nm was measured. New peptide peaks which developed were not all detectable by radioimmunoassay with either antibody. The results suggest that cysteamine causes a change in the structure of somatostatin which probably first involves a reduction of the disulphide bridge and then the N- and C-terminal regions of the molecule thus making it unmeasurable by antisera sensitive to changes in these

  1. SYNTHESIS OF ACRYLONITRILE-N-ISOPROPYLACRYLAMIDE GRAFT COPOLYMERS FOR THE PREPARATION OF THERMAL RESPONSIVE POLYACRYLONITRILE MEMBRANAES%丙烯腈-N-异丙基丙烯酰胺接枝共聚物的合成及其对聚丙烯腈分离膜的改性

    Institute of Scientific and Technical Information of China (English)

    费正东; 万灵书; 钟明强; 徐志康

    2012-01-01

    PNIPAAm with terminal amino groups was synthesized using 2-aminoethanethiol hydrochloride ( AESH) as a chain transfer agent. It was then reacted with methacryloyl chloride to result in macromer, vinly PNIPAAm. A graft copolymer,P( AN-g-NIPAAm) was synthesized through the copolymerization of acrylonitrile (AN) and vinyl PNIPAAm. Using this graft copolymer as an additive, thermal responsive PAN-based membranes were prepared by the immersion precipitation phase inversion method (IPPI). Results from FTIR and NMR indicate that the molecular weight of PNIPAAm can be effectively modulated by changing the concentration of AESH. Then, the weight average molecular weight ( Mw ) was measured by laser scattering. Results of captive bubble contact angle measurements and turbidity analysis show that the graft copolymers are still thermally responsive, which is more remarkable with higher PNIPAAm content. XPS analysis proves thatthe PNIPAAm graft chains are enriched at the membrane surface and pore surface during the course of IPPI because of the hydrophilicity of PNIPAAm. Pure water flux at 40℃ (above the LCST of PNIPAAm) is almost twice as that at 25℃ (below the LCST of PNIPAAm) ,which is due to the conformation change of PNIPAAm chains. All these results demonstrate the synthesized graft copolymers are effective additives for the preparation of thermal responsive PAN membranes.%以巯基乙胺盐酸盐( AESH)为链转移剂、2,2′-偶氮二异丁腈为引发剂,合成了具有端氨基的聚(N-异丙基丙烯酰胺)(PNIPAAm);与甲基丙烯酰氯反应,得到可聚合的PNIPAAm大分子单体;进而与丙烯腈共聚,合成了丙烯腈-N-异丙基丙烯酰胺接枝共聚物(P(AN-g-NIPAAm)).基于浸没沉淀相转化法制备了聚丙烯腈/P(AN-g-NIPAAm)共混膜.红外及核磁分析表明,通过调控AESH的浓度可制备得到不同链长的PNIPAAm大分子单体;用激光光散射进一步测定了共聚物的重均分子量;采用鼓泡接触角及浊度