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Zomer G - One of the best experts on this subject based on the ideXlab platform.

Van Blitterswijk H - One of the best experts on this subject based on the ideXlab platform.

  • Zuivering van kalver- en runderurine via hoge druk vloeistofchromatografie voor onderzoek naar de aanwezigheid van verschillende anabolica
    Rijksinstituut voor Volksgezondheid en Milieu RIVM, 2014
    Co-Authors: Jansen Ehjm, Both-miedema R, Van Blitterswijk H
    Abstract:

    Een eenvoudig isocratisch hoge druk vloeistofchromatografisch systeem wordt beschreven voor de scheiding en zuivering van verschillende typen laag moleculaire anabole verbindingen en enige van hun metabolieten. Voor dit doel worden de verbindingen gechromatografeerd over een "reversed phase" C18 kolom door middel van water-methanol mengsels. Diethylstilbestrol (DES), hexestrol, alfa-R en beta-Dienestrol, Zeranol R, zearalenon, zearalanon, 17-beta-Trenbolone R, 19-nortestosteron, 17-alfa-methyltestosteron en medroxyprogesteron worden van elkaar gescheiden. Behalve voor UV-detectie direct gekoppeld aan de vloeistofchromatograaf bleken de geisoleerde fracties ook geschikt voor separaat vervolgonderzoek met (radio)immunochemische detectie, dunnelaagchromatografie, en/of gaschromatografie-massaspectrometrie.VH

Thiago M. B. F. Oliveira - One of the best experts on this subject based on the ideXlab platform.

  • A glassy carbon electrode modified with silver nanoparticles and functionalized multi-walled carbon nanotubes for voltammetric determination of the illicit growth promoter Dienestrol in animal urine
    Microchimica Acta, 2019
    Co-Authors: Manoel M. S. Lima Filho, Alessandra A. Correa, Francisco D. C. Silva, Francisco A. O. Carvalho, Lúcia H. Mascaro, Thiago M. B. F. Oliveira
    Abstract:

    An electroanalytical method for determining Dienestrol (DNL) in bovine urine samples is described. A glassy carbon electrode (GCE) modified with silver nanoparticles and functionalized multi-walled carbon nanotubes was used as working sensor. The modified GCE displays substantial analytical improvements including an amplified signal, fast electron transfer kinetics, and resistance to fouling. The irreversible oxidation signal of DNL is pH-dependent. Best reactivity is found at pH 3.0, where a typical anodic peak is recorded at 0.8 V (vs. Ag/AgCl). Square-wave voltammetry revealed a 8.4 nM detection limit (1.9 μg L^−1), good repeatability and reproducibility (RSDs

  • a glassy carbon electrode modified with silver nanoparticles and functionalized multi walled carbon nanotubes for voltammetric determination of the illicit growth promoter Dienestrol in animal urine
    Mikrochimica Acta, 2019
    Co-Authors: Manoel Lima M S Filho, Alessandra A. Correa, Francisco D. C. Silva, Francisco A. O. Carvalho, Lúcia H. Mascaro, Thiago M. B. F. Oliveira
    Abstract:

    An electroanalytical method for determining Dienestrol (DNL) in bovine urine samples is described. A glassy carbon electrode (GCE) modified with silver nanoparticles and functionalized multi-walled carbon nanotubes was used as working sensor. The modified GCE displays substantial analytical improvements including an amplified signal, fast electron transfer kinetics, and resistance to fouling. The irreversible oxidation signal of DNL is pH-dependent. Best reactivity is found at pH 3.0, where a typical anodic peak is recorded at 0.8 V (vs. Ag/AgCl). Square-wave voltammetry revealed a 8.4 nM detection limit (1.9 μg L-1), good repeatability and reproducibility (RSDs <5.0%), and good accuracy (93.2-99.4% recovery from spiked samples). The modified electrode is highly stable even in the presence of ions (Na+ and K+), urea and uric acid. The electrochemical sensor fulfills all requisites to be used as forensic device in surveillance of illegal livestock practices. Graphical abstract Schematic presentation of the construction of a glassy carbon electrode modified with silver nanoparticles and functionalized multi-walled carbon nanotubes. This sensor exhibited a remarkable performance for voltammetric detection of the illicit growth promoter Dienestrol in animal urine.

Katsumi Wakabayashi - One of the best experts on this subject based on the ideXlab platform.

  • Promotive effects of diethylstilbestrol, its metabolite (Z,Z-Dienestrol) and a stereoisomer of the metabolite (E,E-Dienestrol) in tumorigenesis of rat mammary glands pregnancy-dependently initiated with radiation
    Carcinogenesis, 1993
    Co-Authors: Hiroshi Inano, Keiko Suzuki, Hiroko Ishii-ohba, Hiroshi Yamanouchi, Masakazu Takahashi, Katsumi Wakabayashi
    Abstract:

    Wistar-MS rats received whole body irradiation with 260 cGy gamma-rays at day 20 of pregnancy and then were treated with diethylstilbestrol (DES), E,E-Dienestrol (E,E-DIES) or Z,Z-Dienestrol (Z,Z-DIES) for 1 year. DES administration caused the highest incidence of mammary tumors with a concomitant reduction of gain in body weight. When E,E-DIES or Z,Z-DIES in pellet form was implanted, the incidence of tumors was significantly lower than that observed in rats treated with DES. To clarify the increased susceptibility to mammary tumorigenesis after DES administration we measured hormone levels in the serum of rats implanted with pellets containing derivatives of the synthetic estrogens. The serum prolactin concentration was significantly increased by DES administration. When E,E-DIES or Z,Z-DIES pellets were implanted the prolactin level was markedly reduced to 4.5% and 0.7% of that observed in DES-treated rats, respectively. In addition, the serum concentrations of estradiol-17 beta and progesterone in rats with Z,Z-DIES pellets were higher than those of rats with DES or E,E-DIES pellets. A large number of DES-induced mammary tumors were positive for both estrogen and progesterone receptors, but no tumors negative for both receptors were obtained. The findings suggest that DES acts directly on radiation-initiated mammary cells via binding with estrogen receptors and/or stimulates the secretion of prolactin from the pituitary glands.

Jansen Ehjm - One of the best experts on this subject based on the ideXlab platform.

  • Zuivering van kalver- en runderurine via hoge druk vloeistofchromatografie voor onderzoek naar de aanwezigheid van verschillende anabolica
    Rijksinstituut voor Volksgezondheid en Milieu RIVM, 2014
    Co-Authors: Jansen Ehjm, Both-miedema R, Van Blitterswijk H
    Abstract:

    Een eenvoudig isocratisch hoge druk vloeistofchromatografisch systeem wordt beschreven voor de scheiding en zuivering van verschillende typen laag moleculaire anabole verbindingen en enige van hun metabolieten. Voor dit doel worden de verbindingen gechromatografeerd over een "reversed phase" C18 kolom door middel van water-methanol mengsels. Diethylstilbestrol (DES), hexestrol, alfa-R en beta-Dienestrol, Zeranol R, zearalenon, zearalanon, 17-beta-Trenbolone R, 19-nortestosteron, 17-alfa-methyltestosteron en medroxyprogesteron worden van elkaar gescheiden. Behalve voor UV-detectie direct gekoppeld aan de vloeistofchromatograaf bleken de geisoleerde fracties ook geschikt voor separaat vervolgonderzoek met (radio)immunochemische detectie, dunnelaagchromatografie, en/of gaschromatografie-massaspectrometrie.VH