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Biomedical subjects

F N Bolkenius

Publications and source records attributed to F N Bolkenius.

27 records · Page 2Linked to original sources
PubMed1985

Polyamine reutilization and turnover in brain.

N1,N2-bis-(2,3-butadienyl)-1,4-butanediamine (MDL 72527) is an irreversible, specific inhibitor of polyamine oxidase, which allows one to completely inactivate this enzyme in all organs of an experimental animal. As a result one observes a linear increase of N1-acetylspermidine and N1-acetylspermine concentrations in brain. The rate of accumulation seems directly proportional to the rate of spermidine, and spermine degradation respectively, and since no compensatory changes of the polyamine synthetic enzymes were induced by inhibition of polyamine oxidase, the rate of acetyl-polyamine accumulation is assumed to be a measure for polyamine turnover. The decrease of brain putrescine levels by 70 percent in the brains of MDL 72527-treated animals suggests the quantitative significance of putrescine reutilisation. Pretreatment of the animals with D,L-alpha-difluoromethylornithine, an irreversible inhibitor of ornithine decarboxylase reduced both, polyamine turnover rate and the extent of putrescine reutilization. Inhibition of GABA-T produced a significant increase of polyamine turnover in brain, in agreement with the known induction of ornithine decarboxylase activity after treatment with inhibitors of GABA-T.

Alkynes↗
PubMed1981

The determination of N1-acetylspermine in mouse liver.

N1-Acetylspermine has been postulated to be an intermediate in the conversion of spermine to spermidine. This compound, together with N1-acetylspermidine has now been detected in the liver of mice which were pretreated with tetrachloromethane. The following methods were used for the identification of N1-acetylspermine: (a) High-pressure liquid-chromatography of the non-derivatized amines on a reversed-phase column, using octane sulfonate for ion-pairing. (b) Thin-layer chromatography of the dansyl derivatives. (c) Mass spectrometry of the dansyl derivatives. Both chromatographic methods allowed the quantitative estimation of N1-acetylspermine and N1-acetylspermidine in the liver of tetrachloromethane-treated animals.

Animals↗
PubMed1981

Interconversion, catabolism and elimination of the polyamines.

Two catabolic pathways exist for spermidine and spermine. One is responsible for the interconversion of the polyamines, a physiological intracellular event. The first and probably rate limiting step of the polyamine interconversion pathway is acetylation in the N1-position by a cytosolic enzyme. The reaction products N1-acetylspermine and N1-acetylspermidine are substrates of the cytoplasmic polyamine oxidase. This enzyme transforms the N1-acetylpolyamines into spermidine and putrescine respectively. N1-Acetylspermidine is at the same time a major urinary excretion product. The factors which control the rates of N1-acetylspermidine degradation by polyamine oxidase versus its elimination via transport are not known. The second catabolic pathway forms putreanine from spermidine and N8-(2-carboxyethyl)-spermidine and spermic acid from spermine. It is catalyzed by the well known serum spermine oxidase. The second step in this reaction sequence, the dehydrogenation of the aldehydes formed by the serum spermine oxidase occurs intracellularly and is catalyzed either by specific or non-specific aldehyde dehydrogenases. The function of this "two compartment reaction sequence" is most probably to protect tissues from extracellular or exogenous (alimentary) polyamines. Its end-products appear to be physiologically indifferent urinary excretion products. Both catabolic pathways may have marked effects on the urinary polyamine pattern. Drugs as well as a variety of physiological and pathological states may influence polyamine catabolism and elimination at various levels, and may cause characteristic alterations in the urinary excretion of free and conjugated polyamines and of the amino acids deriving from the polyamines.

Acetylation↗
PubMed1980

Acetylation of spermidine in polyamine catabolism.

Treatment with thioacetamide (150 mg/kg) was used to enhance polyamine metabolism in rat liver. The increased uptake and catabolism of [14C]spermine and the changes of putrescine, spermidine and spermine concentrations indicated enhanced polyamine turnover rates. The increase of hepatic putrescine concentration was accompanied by an increase of monoacetylputrescine and N1-monoacetylspermidine concentration. In control animals, the latter compound was below detection levels. Thioacetamide treatment also enhanced putrescine excretion, which again was concomitant with an increased excretion of N1-acetylspermidine. The close time-dependent correlation between induced putrescine formation and enhanced formation of N1-acetylspermidine at a time when liver spermidine and spermine concentrations are not changed, favors the notion that acetylation is an essential step in polyamine degradation and elimination. The increase of polyamine oxidase and decrease of acetylpolyamine deacetylase activities in the liver of thioacetamide-treated rats is in line with an increased polyamine turnover, but these enzymes, although essential, are not rate-limiting in the catabolic reactions.

Acetamides↗
PubMed1980

Polyamine oxidase in rat tissues.

An assay procedure for polyamine oxidase in tissue homogenates was devised. The method is based on the degradation of N1,n12-diacetylspermine to N1-acetylspermidine and the determination using TLC of the latter. Polyamine oxidase activity is high in most tissues. Its activity is comparable to that of spermidine and spermine synthase. The independence of this enzyme from cellular proliferation rates and its relatively long biological half-life are indicative of a passive role of polyamine oxidase in the regulation of cellular polyamine levels.

Age Factors↗