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  • Life and Medical Sciences  (3)
  • Analytical Chemistry and Spectroscopy  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Identification of a nitrone as an in vitro metabolite of N-methylamphetamineAbbreviation: NMA = N-methylamphetamine. (1978)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 5 (1978), S. 418-422 
    Details
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The relatively labile nitrone, α-methyl-(N-methylene)benzeneethanamine N-oxide was isolated from incubates of (±)-N-methylamphetamine with fortified liver homogenates from rats and rabbit. Identification of the nitrone was confirmed directly by gas chromatography and gas chromatography mass spectrometry and, after its conversion to isoxazolidine adducts by the action of methyl and ethyl acrylate. An authentic sample of the nitrone was synthesized unequivocally from N-hydroxyamphetamine and formaldehyde. The isomeric nitrone, N-(α-methylbenzeneethylidene)methylamine N-oxide, was also synthesized and its gas chromatographic and gas chromatographic mass spectrometric characteristics determined to confirm that the metabolically formed nitrone was not N-(α-methylbenzeneethylidene)methylamine N-oxide. Two previously unreported metabolites of (±)-N-methylamphetamine, N-hydroxyamphetamine and 1-hydroxy-1-phenyl-2-propanone, were isolated from rat in vitro experiments; the latter metabolite was not produced in vitro by rabbit liver homogenates.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200050609
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  • 2
    Electronic Resource
    Electronic Resource
    Use of mass spectrometry in the identification of In VivoandIn Vitrometabolites of dihydrotachysterol3 in the rat (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 16 (1988), S. 87-92 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The metabolism of dihydrotachysterol3 (DHT3), a vitamin D analogue, has been investigated in vivo in the rat after intraperitoneal injection, and the metabolism of the 25-hydroxylated metabolite of DHT3 was studied in vitro in the isolated perfused rat kidney. A large number of metabolites have been obtained and some have been identified. The rat plasma or kidney perfusate were extracted and the metabolites separated by high-performance liquid chromatography (HPLC) in straight- and reverse-phase systems and using cyano columns. Metabolites were identified, using a photodiode array assembly which monitored the HPLC eluate, by the characteristic ultraviolet spectrum of DHT compounds. Tentative structures were assigned to some of the metabolites obtained on the basis of their mobility in the various HPLC systems used in comparison to that of known metabolites of vitamin D. Gas chromatography/mass spectrometry (GC/MS) and direct probe mass spectrometry have been used to confirm the identity of seven metabolites formed in vitro, of which only two have been definitely shown also to be formed in vivo. GC/MS was carried out after derivatization forming trimethylsilyl ethers, n-butyl boronate cyclic esters, and N-O-methyl oximes before and after oxidation with sodium periodate and/or reduction with sodium borohydride. Molecular ions of these compounds are usually of low abundance and characteristic mass fragments at m/z 273, 255 and 121 are always seen with metabolites of DHT.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200160117
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  • 3
    Electronic Resource
    Electronic Resource
    Purification of human granulocytes by centrifugal elutriation and measurement of transmembrane potential (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 104 (1980), S. 425-431 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Viable cell samples containing 93% pure granulocytes were obtained from human blood using the techniques of dextran sedimentation followed by centrifugal elutriation. The resting transmembrane potential (Em) of human granulocytes was estimated using the fluorescent lipophilic cation, Di-S-C3(5), from the null point for potassium - i.e., the external K concentration at which there is no change in Em in response to valinomycin (a K ionophore). The Em of human granulocytes, as calculated from the Nernst potential for K at the null point, is approximately - 100 mV. Data indicate that this large transmembrane potential is due in part to the presence of an electrogenic Na-K pump in human granulocytes which is stimulated by external potassium and inhibited by ouabain.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041040315
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  • 4
    Electronic Resource
    Electronic Resource
    Transmembrane potential changes associated with superoxide release from human granulocytes (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 106 (1981), S. 75-83 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Treatment of human granulocytes with concanavalin A, phorbol myristate acetate (PMA), N-formyl-methionyl-leucyl-phenylalanine (FMLP), and A23187 (a calcium ionophore) stimulates the release of superoxide anion and the generation of chemiluminescence. The fluorescent probe, Di-S-C3(5), has been used to monitor shifts in membrane potential in response to these stimulants which precede the secretion of superoxide. Concanavalin A, PMA, and FMLP induce a biphasic shift in transmembrane potential (Em), i.e., a rapid depolarization followed by a prolonged hyperpolarization. This depolarization is dependent on both external sodium and calcium while the hyperpolarization is inhibited by ouabain which blocks the electrogenic Na-K pump. In contrast, A23187 induces a rapid and prolonged depolarization. This monophasic shift in Em is dependent on external calcium. These results suggest that depolarization acts as a signal to initiate events associated with the “respiratory burst” of these phagocytes.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041060109
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  • 5
    Electronic Resource
    Electronic Resource
    Increase in copy number of an integrated vector during continuous culture of Hansenula polymorpha expressing functional human haemoglobin (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Yeast 10 (1994), S. 1569-1580 
    Details
    ISSN: 0749-503X
    Keywords: Hansenula ; haemoglobin ; integration ; continuous culture ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Recombinant human haemoglobin A (rHbA) was produced by a leucine-requiring strain of Hansenula polymorpha which had been transformed with an integration vector containing the Saccharomyces cerevisiae LEU2 gene and cDNAs for the expression of α and β globin each driven by the H. polymorpha MOX promoter. After 40 generations in a chemostat it was found that the integrated vector had become amplified in the host strain. In some cases this led to an increase in LEU2 gene dosage, but a loss of globin expression cassettes. In other cases the globin gene dosage also increased. These changes coincided with an increase in rHbA production in the culture, which was reversed when the dilution rate was increased. Isolates from a chemostat culture producing elevated levels of rHbA were grown in fed-batch fermentations, resulting in higher productivities than when inoculated with the parent strain. The rHbA produced was purified and characterized. Oxygen binding studies and electrospray mass spectrometry showed that the rHbA had been processed and assembled correctly, and behaved as a fully functional co-operative tetramer.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/yea.320101206
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