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  • 1980-1984  (3)
  • 1955-1959
  • Lignin degradation  (2)
  • 3-Methoxy-4-hydroxyphenylglycol  (1)
  • 1
    ISSN: 1432-2072
    Keywords: Clonidine ; Withdrawal ; Normetanephrine ; Metanephrine ; Vanillylmandelic acid ; 3-Methoxy-4-hydroxyphenylglycol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Abrupt cessation of clonidine treatment in hypertensive patients may precipitate a withdrawal syndrome. Since this drug is likely to be more widely prescribed to normotensive patients with neuropsychiatric diseases, we studied neurochemical, cardiovascular, and behavioral changes upon placebo substitution in seven patients receiving clonidine (6 μg/kg/day for 3 weeks) for treatment of alcohol amnestic disorder. Urinary excretion of all major catecholamine metabolites returned to pretreatment levels 3–5 days after discontinuing clonidine, without significant overshoot. The percentage increase during clonidine withdrawal of the norepinephrine metabolite normetanephrine was greater than were those of vanillylmandelic acid, 3-methoxy-4-hydroxyphenylglycol (MHPG), or the epinephrine metabolite metanephrine. Excretion of the dopamine metabolites homovanillic acid and 3-methoxytyramine did not change. Total plasma MHPG, heart rate, and mean arterial pressure were significantly elevated above pretreatment values 72 h after the last dose of clonidine. There was an enhancement of episodic memory compared to predrug values but no other behavioral changes were noted during clonidine withdrawal. These findings are consistent with augmented catecholamine release and central noradrenergic activation which may produce psychopathology in some psychiatric patients during clonidine withdrawal.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-072X
    Keywords: Phanerochaete chrysosporium ; Lignin degradation ; Veratryl alcohol ; Secondary metabolism ; Mutants ; Phenol oxidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A pleiotropic mutant of Phanerochaete chrysosporium 104-2 lacking phenol oxidase and unable to form fruit bodies and a revertant strain 424-2 were isolated after UV mutagenesis. Strains 104-2 and 424-2 had no apparent dysfunction in primary metabolism with glucose as a carbon source. Unlike the wild type strain and strain 424-2, strain 104-2 was unable to evolve 14CO2 from 14C ring, side chain and 3-O-14C-methoxy labeled lignin. In addition, strain 104-2 was unable to evolve 14CO2 from a variety of lignin model compounds including 14C-4′-methoxy labeled veratrylglycerol-β-guaiacyl (V) ether, γ-14C-guaiacylglycerol-β-guaiacyl ether (VI), as well as 1-(14C-4′-methoxy, 3′-methoxyphenyl)1,2 propene (III) and 1-(14C-4′-methoxy-3′-methoxyphenyl) 1,2 dihydroxypropane (IV). The addition of peroxidase/H2O2 to cultures of strain 104-2 did not alter its capacity to degrade the labeled lignins. A variety of unlabeled lignin model compounds previously shown to be degraded by the wild type organism including β-aryl ether dimers and diaryl propane dimers were also not degraded by the mutant 104-2. The revertant strain 424-2 regained the capacity to degrade these compounds. The substrates described are degraded by oxygen requiring system(s) expressed during the secondary phase of growth, suggesting this pleiotropic mutant is possibly defective in the onset of postprimary metabolism. The inability of the mutant to produce the secondary metabolite veratryl alcohol and to elaborate enzymes in the veratryl alcohol biosynthetic pathway supports this hypothesis.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-072X
    Keywords: Phanerochaete chrysosporium ; Lignin model compounds ; Lignin degradation ; Diarylpropane ; α,β cleavage ; Anisyl alcohol ; Lignin ; Basidiomycete
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The white rot basidiomycete Phanerochaete chrysosporium metabolized 1-(3′,4′-diethoxyphenyl)-1,3(dihydroxy)-2-(4′'-methoxyphenyl)-propane (XII) in low nitrogen stationary cultures, conditions under which the ligninolytic enzyme system is expressed. 3,4-Diethoxybenzyl alcohol (IV), 1,2(dihydroxy)-1-(4′-methoxyphenyl)ethane (XX) and anisyl alcohol were isolated as metabolic products indicating an initial α, β bond cleavage of this dimer. Exogenously added XX was rapidly converted to anisyl alcohol, indicating that XX is an intermediate in the metabolism of XII. Fungal cleavage of the α, β bond of 1-(3′-4′-diethoxyphenyl)-1-(hydroxy)-2-(4′'-methoxyphenyl)ethane (XI) also occurred, indicating that a γ hydroxymethyl group is not a prerequisite for this reaction. P. chrysosporium also metabolized 1-(4′-ethoxy-3′-methoxyphenyl)-2,2(dihydroxy)-2-(4′'-methoxyphenyl)propane-1-ol (XIII). The major products of the degradation of this triol included 4-ethoxy-3-methoxybenzyl alcohol (III) and 2-hydroxy-1-(4′-methoxyphenyl)-1-oxoethane (XXI). The nature of the products formed indicates that this triol is also cleaved directly at the α,β bond. The significant difference in the nature of the products formed from the diaryl propane (XII) and the triol (XIII), however, suggests that XIII is not an intermediate in the major pathway for the degradation of XII. Metabolites were identified after comparison with chemically synthesized standards by GLC-mass spectrometry.
    Type of Medium: Electronic Resource
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