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Sample records for aminoethanethiol

  1. Phosphopeptide Characterization by Mass Spectrometry using Reversed-Phase Supports for Solid-Phase β-Elimination/Michael Addition

    OpenAIRE

    Nika, Heinz; Lee, Jaehoon; Willis, Ian M.; Angeletti, Ruth Hogue; Hawke, David H.

    2012-01-01

    We have adapted the Ba2+ ion-catalyzed concurrent Michael addition reaction to solid-phase derivatization on ZipTipC18 pipette tips using 2-aminoethanethiol as a nucleophile. This approach provides several advantages over the classical in-solution-based techniques, including ease of operation, completeness of reaction, improved throughput, efficient use of dilute samples, and amenability to automation. Phosphoseryl and phosphothreonyl peptides, as well as phosphoserine peptides with adjoining...

  2. Phosphopeptide Enrichment by Covalent Chromatography after Derivatization of Protein Digests Immobilized on Reversed-Phase Supports

    OpenAIRE

    Nika, Heinz; Nieves, Edward; Hawke, David H.; Angeletti, Ruth Hogue

    2013-01-01

    A rugged sample-preparation method for comprehensive affinity enrichment of phosphopeptides from protein digests has been developed. The method uses a series of chemical reactions to incorporate efficiently and specifically a thiol-functionalized affinity tag into the analyte by barium hydroxide catalyzed β-elimination with Michael addition using 2-aminoethanethiol as nucleophile and subsequent thiolation of the resulting amino group with sulfosuccinimidyl-2-(biotinamido) ethyl-1,3-dithioprop...

  3. Metabolic perturbation of an essential pathway: evaluation of a glycine precursor of Coenzyme A

    OpenAIRE

    Rothmann, Michael; Kang, MinJin; Villa, Reymundo; Ntai, Ioanna; La Clair, James J.; Kelleher, Neil L.; Chapman, Eli; Burkart, Michael D.

    2013-01-01

    Pantetheine, and its corresponding disulfide pantethine, play a key role in metabolism as a building block of coenzyme A (CoA), an essential cofactor utilized in ~4% of primary metabolism and central to fatty acid, polyketide, and non-ribosomal peptide synthases. Using a combination of recombinant engineering and chemical synthesis, we demonstrate that the disulfide of N-pantoylglycyl-2-aminoethanethiol (GlyPan), with one carbon deletion from pantetheine, can rescue a mutant E. coli strain MG...

  4. Fluorescence Quenching of CdTe Nanocrystals by Bound Gold Nanoparticles in Aqueous Solution

    OpenAIRE

    Jian ZHANG; Badugu, Ramachandram; Lakowicz, Joseph R.

    2008-01-01

    Water-soluble gold nanoparticles with an average diameter of 5 nm were prepared with carboxylic acid terminated thiol ligands. These ligands contain zero to eight methylene moieties. CdTe nanocrystals with an average diameter of 5 nm were synthesized with aminoethanethiol capping. These nanocrystals displayed characteristic absorption and emission spectra of quantum dots. The amine terminated CdTe nanocrystals and carboxylic-acid-terminated gold nanoparticles were conjugated in aqueous soluti...

  5. Highly luminescent water-soluble CdTe quantum dots

    OpenAIRE

    Wuister, SF; Swart, A.N.; van Driel, F; Hickey, SG; Donega, CD; Swart, Ingmar

    2003-01-01

    Colloidal CdTe quantum dots prepared in TOP/DDA (trioctylphosphine/dodecylamine) are transferred into water by the use of aminoethanethiol.HCl (AET) or mercaptopropionic acid (MPA). This results in an increase in the photoluminescence quantum efficiency and a longer exciton lifetime. For the first time, water-soluble semiconductor nanocrystals presenting simultaneously high band-edge photoluminescence quantum efficiencies (as high as 60% at room temperature), monoexponential exciton decays, a...

  6. Reaction of Phosphorylated and O-Glycosylated Peptides by Chemically Targeted Identification at Ambient Temperature

    OpenAIRE

    Rusnak, Felicia; Zhou, Jie; Hathaway, Gary M.

    2004-01-01

    Conditions for carrying out chemically targeted identification of peptides containing phosphorylated or glycosylated serine residues have been investigated. Ba(OH)2 was used at ambient temperature to catalyze the β-elimination reaction at 25°C. Nucleophilic addition of 2-aminoethanethiol was performed in both parallel and tandem experiments. The method was demonstrated by the reaction of β-casein tryptic digest phosphopeptides and an O-glycosylated peptide. Contrary to an earlier report by ot...

  7. Synthesis and characterization of polystyrene-poly(ethylene oxide)-heparin block copolymers

    OpenAIRE

    Vulić, I.; Okano, T.; Kim, S W; J. Feijen

    1988-01-01

    A procedure for the preparation of new block copolymers composed of a hydrophobic block of polystyrene, a hydrophilic spacer-block of poly(ethylene oxide) and a bioactive block of heparin was investigated. Polystyrene with one amino group per chain was synthesized by free radical oligomerization of styrene in dimethylformamide, using 2-aminoethanethiol as a chain transfer agent. This amino group was used in the coupling reaction with amino-telechelic poly(ethylene oxide) to produce an AB type...

  8. Utilizing the Trispyrazolyl Borate Ligand for the Mimicking of O2-Activating Mononuclear Nonheme Iron Enzymes.

    Science.gov (United States)

    Sallmann, Madleen; Limberg, Christian

    2015-10-20

    Mononuclear, O2-activating nonheme iron enzymes are a fascinating class of metalloproteines, capable of realizing the most different reactions, ranging from C-H activation, via O atom transfer to C-C bond cleavage, in the course of O2 activation. They can lead us the way to achieve similar reactions with comparable efficiency and selectivity in chemical laboratories, which would be highly desirable aiming at accessing value-added products or to achieve degradation of unwanted compounds. Hence, these enyzmes motivate attempts to construct artificial low-molecular weight analogues, mimicking structural or functional characteristics. Such models can, for instance, provide insights about which of the features inherent to an active site are essential and guarantee the enzyme function, and from this kind of information the minimal requirements for a biomimetic or bioinspired complex that may be applied in catalysis can be derived. On the other hand, they can contribute to an understanding of the enzyme functioning. In order to create such replicates, it is important to faithfully mimic the surroundings of the iron centers in their active sites. Most of them feature two histidine residues and one carboxylate donor, while a few exhibit a deceptively simple (His)3Fe active site. For the simulation of these, the trispyrazolyl borate ligand (Tp) particularly offers itself, as the facial arrangement of three pyrazole donors is reminiscent of the three histidine-derived imidazole donors. The focus of this Account will be on bioinorganic/biomimetic research from our laboratory utilizing Tp ligands to develop molecular models for (i) two representatives of the (His)3Fe-enzyme family, namely, the cysteine dioxygenase (CDO) and acetyl acetone dioxygenase (Dke1), (ii) a related but less well-explored variant of the CDO-the 2-aminoethanethiol dioxygenase-as well as (iii) the 2-His-1-carboxylate representative 1-aminocyclopropane-1-carboxylic acid oxidase (ACCO). The CDO catalyzes the

  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. Metabolic perturbation of an essential pathway: evaluation of a glycine precursor of coenzyme A.

    Science.gov (United States)

    Rothmann, Michael; Kang, MinJin; Villa, Reymundo; Ntai, Ioanna; La Clair, James J; Kelleher, Neil L; Chapman, Eli; Burkart, Michael D

    2013-04-24

    Pantetheine and its corresponding disulfide pantethine play a key role in metabolism as building blocks of coenzyme A (CoA), an essential cofactor utilized in ~4% of primary metabolism and central to fatty acid, polyketide, and nonribosomal peptide synthases. Using a combination of recombinant engineering and chemical synthesis, we show that the disulfide of N-pantoylglycyl-2-aminoethanethiol (GlyPan), with one fewer carbon than pantetheine, can rescue a mutant E. coli strain MG1655ΔpanC lacking a functional pantothenate synthetase. Using mass spectrometry, we show that the GlyPan variant is accepted by the downstream CoA biosynthetic machinery, ultimately being incorporated into essential acyl carrier proteins. These findings point to further flexibility in CoA-dependent pathways and offer the opportunity to incorporate orthogonal analogues. PMID:23550886

  11. Synthesis of functionalized poly(ester carbonate) with laminin-derived peptide for promoting neurite outgrowth of PC12 cells.

    Science.gov (United States)

    Xing, Dongming; Ma, Lie; Gao, Changyou

    2014-10-01

    Maleimide-functionalized poly(ester carbonate)s are synthesized by ring-opening copolymerization of furan-maleimide functionalized trimethylene carbonate (FMTMC) with L-lactide and a subsequent retro Diels-Alder reaction. The maleimide groups on poly(ester carbonate)s are amenable to Michael addition with thiol-containing molecules such as 3-mercapto-1-propanol, 2-aminoethanethiol hydrochloride, and mercaptoacetic acid under mild conditions, enabling the formation of biodegradable materials with various functional groups (e.g., hydroxyl, amine, and carboxyl). In particular, the maleimide-functionalized poly(ester carbonate) is clicked with a laminin-derived peptide CQAASIKVAV. In vitro culture of PC12 cells shows that the maleimide-functionalized polymers, especially the CQAASIKVAV-grafted one, could support cell proliferation and neurite outgrowth. The maleimide-functionalized poly(ester carbonate)s provide a versatile platform for diverse functionalization and have comprehensive potential in biomedical engineering. PMID:24962245

  12. Syntheses and characterisation of new dioxouranium(VI) complexes with tridentate sulfur donor ligands

    International Nuclear Information System (INIS)

    New dioxouranium(VI) complexes with the tridentate dibasic Schiff bases derived from salicylaldehyde, 5-chlorosalicylaldehyde, 5-bromosalicylaldehyde, 5-nitrosalicylaldehyde, 3,5-dichlorosalicylaldehyde, 4-methoxysalicylaldehyde, 5-methoxysalicylaldehyde, 3-ethoxysalicylaldehyde, 2-hydroxy-1-napththaldehyde and 2-aminoethanethiol have been synthesised by the reaction of methanolic solution of dioxouranium(VI) acetate dihydrate and the Schiff base. The Schiff bases behave as ONS tridentate donor dibasic ligands. The complexes are of the type UO2L.CH3OH, where LH2 = the tridentate, dibasic Schiff base. The complexes have been characterised on the basis of elemental analysis, infrared and electronic spectra, conductance, magnetic susceptibility and molecular weight measurements. The complexes are diamagnetic, monomers and octahedral. (author)

  13. 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.

  14. 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.

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

    International Nuclear Information System (INIS)

    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)6]3-/4- as a redox probe revealed that the Au-AET-SWCNT-CoTAPc showed much lower (∼10 times) electron-transfer resistance (R et) and much higher (∼10 times) apparent electron-transfer rate constant (k 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

  16. Depletion of bovine pituitary prolactin by cysteamine involves a thiol:disulfide mechanism

    International Nuclear Information System (INIS)

    Cysteamine [2-aminoethanethiol (CySH)] reduces measurable PRL concentrations in vivo and in vitro. Since secretion is also inhibited, CySH may block conversion from a poorly assayable hormone storage form(s) to readily assayable, releasable PRL. This would represent a previously unrecognized mechanism for secretory regulation. We undertook the present study to identify the sites involved in the loss of measurable PRL (depletion) induced by cysteamine. The disulfide cystamine was ineffective on secretory granules unless combined with reduced glutathione, indicating the generation of the active CySH-thiol form. Pretreatment of granules with thiol-blocking agents resulted in dose-dependent enhancement of CySH inhibition, achieving nearly complete inhibition with 5 mM iodoacetamide. In contrast, pretreatment with reduced glutathione or dithiothreitol, respectively, impaired or abolished the CySH effect. These data suggest that the mechanism by which CySH causes PRL depletion is mediated by granule disulfides and the -SH of CySH. The regulation of thiol:disulfide equilibria appears to be an important determinant of the detectability of PRL storage forms and of their secretion

  17. Surface-confined crown ether-capped gold nanoclusters: investigation on their electrochemical behavior

    International Nuclear Information System (INIS)

    A new ligand 18-crown-6–aminoethanethiol (18C6–AET), in which crown ether–ammonium ion interaction was exploited, had been designed and synthesized. An estimated HOMO–LUMO gap of 0.259 eV for the 18C6–AET complex indicated a definite interaction between 18C6 and AET. Consequently, multivalent interactions interplayed for the stabilization of gold nanoclusters resulting in confined cationic clusters having a diameter in 2–5-nm range in aqueous medium. The modified indium tin oxide electrodes with immobilized 18C6–AET-capped gold nanoclusters represented a metal–insulator–semiconductor junction across which the characteristic interfacial electron transport was unraveled. A heterogeneous electron transfer rate constant of 5.082 s−1 with a transfer coefficient of 0.51 was obtained for the quasi-reversible process, complying with a core-to-core electron hopping transport along with through-bond tunneling across the linker.

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

    International Nuclear Information System (INIS)

    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−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−1. • The nanocomposite exhibited a long-term cycle stability

  19. A novel electro analytical nanosensor based on graphene oxide/silver nanoparticles for simultaneous determination of quercetin and morin

    International Nuclear Information System (INIS)

    Graphical abstract: - Abstract: In this report, silver nanoparticles (AgNPs) with the mean diameters of 10-30 nm were self-assembled onto the surfaces of 2-aminoethanethiol (2-AET) functionalized graphene oxide (AETGO) sheets. The graphene oxide (GO) and AgNPs-AETGO nanocomposites were characterized by a transmission electron microscope (TEM), x-ray photoelectron spectroscopy (XPS), reflection–absorption infrared spectroscopy (RAIRS) and the x-ray diffraction (XRD). The simultaneous determination of quercetin (QR) and morin (MR) has been performed on glassy carbon electrode (GCE) modified with AgNPs-AETGO (AgNPs-AETGO/GCE). QR presented an oxidation step at Ea of 200 mV and reduction step at Ec of 150 mV and RT presented an oxidation step at Ea of 600 mV at AgNPs-AETGO/GCE by cyclic voltammetry (CV). The linearity ranges and the detection limits of QR and MR were 1.0 × 10-8 - 5.0 × 10-6 M and 3.3 × 10-9 M, respectively. The AgNPs-AETGO/GCE was also applied to real samples for the simultaneous determination of QR and MR. Thus the developed method can be adopted as an alternative to the published chromatographic, spectrophotometric and electroanalytical methods for simultaneous determination of QR and MR

  20. Ligand-induced dependence of charge transfer in nanotube-quantum dot heterostructures.

    Science.gov (United States)

    Wang, Lei; Han, Jinkyu; Sundahl, Bryan; Thornton, Scott; Zhu, Yuqi; Zhou, Ruiping; Jaye, Cherno; Liu, Haiqing; Li, Zhuo-Qun; Taylor, Gordon T; Fischer, Daniel A; Appenzeller, Joerg; Harrison, Robert J; Wong, Stanislaus S

    2016-08-25

    As a model system to probe ligand-dependent charge transfer in complex composite heterostructures, we fabricated double-walled carbon nanotube (DWNT)-CdSe quantum dot (QD) composites. Whereas the average diameter of the QDs probed was kept fixed at ∼4.1 nm and the nanotubes analyzed were similarly oxidatively processed, by contrast, the ligands used to mediate the covalent attachment between the QDs and DWNTs were systematically varied to include p-phenylenediamine (PPD), 2-aminoethanethiol (AET), and 4-aminothiophenol (ATP). Herein, we have put forth a unique compilation of complementary data from experiment and theory, including results from transmission electron microscopy (TEM), near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, Raman spectroscopy, electrical transport measurements, and theoretical modeling studies, in order to fundamentally assess the nature of the charge transfer between CdSe QDs and DWNTs, as a function of the structure of various, intervening bridging ligand molecules. Specifically, we correlated evidence of charge transfer as manifested by changes and shifts associated with NEXAFS intensities, Raman peak positions, and threshold voltages both before and after CdSe QD deposition onto the underlying DWNT surface. Importantly, for the first time ever in these types of nanoscale composite systems, we have sought to use theoretical modeling to justify and account for our experimental results. Our overall data suggest that (i) QD coverage density on the DWNTs varies, based upon the different ligand pendant groups used and that (ii) the presence of a π-conjugated carbon framework within the ligands themselves coupled with the electron affinity of their pendant groups collectively play important roles in the resulting charge transfer from QDs to the underlying CNTs. PMID:27368081

  1. Synthesis, characterization and biodistribution of neutral and lipid-soluble 99mTc-bisaminoethanethiol spiperone derivatives: Possible ligands for receptor imaging with SPECT

    International Nuclear Information System (INIS)

    Using parts of the molecular structure of spiperone, two new ligand systems for complexation with [99mTc]technetium were prepared in order to develop potential receptor imaging agents for single photon emission computer tomography (SPECT). The bis-aminoethanethiols (BAT): 1-benzyl-4-(2-mercapto-2-methyl-4-aza-pentyl)-4-(2-mercapto-2-methyl- propylamino)-piperidine (benzylpiperidyl-BAT, BP-BAT) and 1-[3-(4-fluorobenzoyl)-propyl]-4-(2-mercapto-2-methyl-4-aza-pentyl)-4-(2- mercapto-2-methyl-propylamino)-piperidine (butyrophenoylpiperidyl-BAT, BUP-BAT) form stable, neutral and lipid soluble complexes with [99mTc]technetium at pH ≥ 11 using SnCl2 as reducing agent in nearly quantitative radiochemical yields. Biodistribution of 99mTc-BP-BAT and 99mTc-BUP-BAT in rats showed a moderate clearance from blood and low uptake and retention in the liver, whereas brain uptake was moderate, however with prolonged brain retention. On the other hand, significant accumulations and retentions were observed in heart, kidney and lung with increasing oxygen/blood ratios up to 24 h. Within 24 h p.i. 22 and 29% of the injected dose (i.d.) of 99mTc-BP-BAT and 99mTc-BUP-BAT were eliminated by hepatobiliary excretion whereas 22% i.d. of both 99mTc-BAT complexes were excreted into the urine. Although first biodistribution studies of 99mTc-BP-BAT and 99mTc-BUP-BAT in rats showed relatively low brain uptake, the high uptake in peripheral, receptor rich organs indicates that compounds of this type may be used as a basis for further structural modification to develop agents with optimal properties for cerebral or peripheral receptor imaging with SPECT

  2. Effects of the radioprotector WR-1065 on aspects of DNA metabolism and cell cycle progression in CHO AA8 and human HSF4 cells

    International Nuclear Information System (INIS)

    The radioprotector WR-1065 (2-[(aminopropyl) amino]ethanethiol) is known to protect mammalian cells from the cytotoxic and mutagenic effects of radiation exposure, but the exact mechanisms involved in this protection are not fully known. The effect of WR-1065 on a variety of cellular processes in two cell lines was examined to determine how it may provide protection. Incubation of Chinese hamster ovary AA8 cells in 4 mM WR-1065 did not significantly affect the DNA synthetic rate. Autoradiographic analysis of heavily labeled nuclei of AA8 cells showed no significant difference in the size of the S phase population of WR-1065 treated versus control cells for up to 3 h. An examination of the effect of WR-1065 on repair synthesis, as measured by unscheduled DNA synthesis (UDS) in cells exposed to 15 Gy of gamma-rays, showed no difference between treated and sham treated cells for up to 2 h exposure time. A significant reduction in the amount of UDS was seen in cells treated with the protector for 2.5 and 3h. WR-1065 concentrations ranging from 0.5 mM to 4 mM were not cytotoxic to normal human skin fibroblast cells (HSF4) for exposure to 137Cs gamma-rays resulted in a protection factor of 3.5, almost twice that observed for AA8 cells with 4 mM Wr-1065. Growth of AA8 cells in either alpha-minimal essential medium or McCoy's 5 a medium did not affect the alteration in cell cycle progression observed. These data suggest that perturbations in cell cycle progression, rather than direct effects on the rate of DNA synthesis, could play a role in the increased survival and reduced mutation frequencies observed in the presence of WR-1065 by allowing more time for the repair of DNA damage prior to division

  3. Preparation and animal studies of 99Tcm-TRODAT-1 as a dopamine transporter imaging agent

    International Nuclear Information System (INIS)

    Objective: To develop 99Tcm labelled dopamine transporter (DAT) imaging agent 99Tcm-(2β-[N,N'-bis(2-mercaptoethyl) ethylenediamin] methyl, 3β-(4-chlorophenyl) tropane (TRODAT-1) for evaluating changes of DAT in patients with Parkinson's disease. Methods: TRODAT-1 was synthesized from cocaine by stepwise reactions adding two aminoethanethiol units. Using SnCl2 as reducing agent, and in the presence of Naglucoheptonate, 99Tcm-TRODAT-1 was prepared. Animal studies have been performed in rats and normal monkeys. Results: The structure of TRODAT-1 was confirmed by IR, 1HNMR and MS. Radiochemical purity of 99Tcm-TRODAT-1 was over 90%, and stable for 24 h at room temperature. The partition coefficient in octanol and buffer was 132 and 154 at pH 7.0 and 7.4 respectively. Biodistribution displayed relatively low uptake in rat brain (0.28 and 0.12% ID/org at 2 min and 60 min post injection, respectively), but high uptake in liver (16.7% ID/organ at 60 min), steady uptake in kidney (maintained 3% ID/organ). The major radioactivity was excreted by hepatobiliary systems. The distribution in rat's brain showed that striatal uptake were 0.193, 0.189, 0.142 and 0.136% ID/g at 2, 30, 60 and 120 min, respectively. The ratios of striatal to cerebellar, striatal to hippocampal and striatal to cortical were 4.45 2.55 and 3.15 at 120 min post injection, respectively. Brain image studies in monkeys indicated that TRODAT was uptake and retained in the basal ganglia, where containing DAT abundantly. Ratio of regional brain uptakes of striatum/cerebellum was 1.56 as measured by SPECT imaging at 120 min. Conclusions: Above results showed the stable, neutral and lipophilic complex 99Tcm-TRODAT-1 can cross the blood brain barrier, and be selectively concentrated by the striatal area, where containing DAT abundantly. High quality images of monkeys were also obtained. It suggested that 99Tcm-TRODAT-1 may be a promising agent for clinical application