Ammonium acetate decreased in a concentration-dependent manner the phagocytic uptake of mannosylated latex microspheres and of yeast by immortalized human microglia (CHME-5) and astroglioma (GL-15) cells. In both cell lines ammonium acetate affected also the secretion of certain cytokines. The most conspicuous effects were the following: in both cell lines ammonium acetate enhanced greatly the secretion of tumor necrosis factor-alpha in the absence of any other stimulus. in the human microglia cells ammonia decreased the constitutive secretion of interleukin-6, but it enhanced the stimulated (interleukin-1 alpha, tumor necrosis factor-alpha, gamma-interferon and gamma-interferon + tumor necrosis factor-alpha) secretion of interleukin-8. In the astroglioma cell line, the stimulated release of tumor necrosis factor-alpha, interleukin-6 and interleukin-8 was diminished by ammonium acetate. The magnitude of the ammonia-effect depended on the stimulating agent (lipopolysaccharide, interleukin-1 alpha, tumor necrosis factor-alpha, gamma-interferon). The results are discussed with regard to their potential importance in the pathogenesis of human diseases with elevated blood and brain ammonia concentrations.

Acetates↗

PubMedDate not supplied

Characterization of amine oxidase activities in macrophages from human peripheral blood.

A sensitive assay for the determination of hydrogen peroxide formation and a method for the identification and characterization of amine oxidases in cells and other oxidase sources of limited accessibility are described. The enzymes are characterized by substrate and inhibitor patterns. The method was applied to the identification and characterization of polyamine oxidizing enzymes in macrophages from human peripheral blood. The major oxidase activity in these cells was found to be a tissue-type polyamine oxidase, but with distinct characteristics. Diamine oxidase and monoamine oxidase activities were also detected in homogenates of macrophages. Since the formation of toxic products by a releasable polyamine oxidase is supposed to be an integral part of a regulatory function of macrophages, we consider our work as a basis for the elucidation of this function.

Amine Oxidase (Copper-Containing)↗

PubMedDate not supplied

Functional and metabolic changes in intestinal mucosa of rats after enteral administration of ornithine alpha-ketoglutarate salt.

BACKGROUND: Ornithine alpha-ketoglutarate salt efficiently improves the nutritional status of protein-depleted patients. Our aim was to explore the effects of ornithine alpha-ketoglutarate supplementation on intestinal physiology in healthy animals. METHODS: Rats were given a nutritive mixture supplemented with ornithine alpha-ketoglutarate (1 g.kg-1 per day) by enteral route for 7 days. Controls received the diet supplemented with casein acid hydrolysate under isoenergetic and isonitrogenous conditions. RESULTS: An adaptive hyperplasia of the villi and an increase in the brush-border hydrolase activities were observed in rats receiving ornithine alpha-ketoglutarate. Because of the high ornithine aminotransferase activity, ornithine alpha-ketoglutarate-derived ornithine was extensively transaminated with a concomitant enhancement of ornithine decarboxylation. Surprisingly, with glutamate and putrescine, the products of ornithine transamination and decarboxylation, gamma-aminobutyric acid accumulated (10-fold to 16-fold) dramatically in the intestinal mucosa of rats treated with ornithine alpha-ketoglutarate. Because gamma-aminobutyric acid formation was completely prevented by the diamine oxidase inhibitor aminoguanidine but was not modified after inactivation of ornithine aminotransferase by 5-fluoromethylornithine, it is evident that gamma-aminobutyric acid is formed in the mucosa from ornithine via putrescine as an intermediate. CONCLUSIONS: It is assumed that enhanced gamma-aminobutyric acid formation in the intestinal mucosa by ornithine alpha-ketoglutarate treatment might be of physiologic importance in the regulatory processes of cell growth and differentiation.

Amino Acids↗

PubMedDate not supplied

Polyamines in human breast cancer and its relations to classical prognostic features: clinical implications.

Experimental evidence suggest an important role of polyamines in breast cancer development. Polyamines have been determined in tissue and erythrocyte samples from 100 patients with primary invasive breast cancer and 30 patients with fibroadenomas. Statistical analysis was performed in order to determine the prognostic value of the polyamine patterns of tumor tissues and erythrocytes in comparison with clinical and histological prognostic factors. In malignant tissues, polyamine levels were significantly higher than in benign tissues. They correlated with markers of tumor aggressivity (axillary node involvement and especially with markers of high mitotic rate as Ki-67 staining, histological grade). No correlation was found between estrogen and progesterone status, tumor size and polyamine concentrations. Erythrocyte polyamines levels were identical between cancer patients and controls. The knowledge of the polyamine pattern in breast cancer could become useful in clinical practice particularly if polyamine metabolism is targeted as a therapeutic approach.

Breast Neoplasms↗

PubMedDate not supplied

Dimethylsilane polyamines: cytostatic compounds with potentials as anticancer drugs. II. Uptake and potential cytotoxic mechanisms.

Dimethylsilane tetramines are structural analogues of spermine with a (CH3)2 Si-group incorporated into the central carbon chain. They have potential as anticancer drugs. Their cytotoxic effect was considered to rely mainly on their polyamine antagonist property. In order to obtain new ideas about cellular mechanisms, which are potential targets of the dimethylsilane polyamines, the effects of these compounds on some basic cell functions, such as protein and DNA synthesis, and calmodulin antagonism were studied. In addition, their mode of accumulation in cells was investigated. It became evident that the intracellular accumulation of dimethylsilane polyamines is almost exclusively achieved via the polyamine transport system. However, the exchange of a part of the intracellular natural polyamines against dimethylsilane polyamines has only a small effect on polyamine uptake. Binding to the endoplasmic reticulum and inhibition of protein synthesis are presumably important for the cytotoxic action of bis(11-amino-4,8-diazaundecyl)dimethylsilane, a hexamine, but seem of no importance for the tetramines. Calmodulin antagonism, however, is likely to contribute to their cytotoxic effect.

Animals↗

PubMedDate not supplied

Polyamine deprivation enhances antitumoral efficacy of chemotherapy.

We reported previously that polyamine deprivation by feeding a polyamine deficient diet combined with gastrointestinal tract decontamination and polyamine oxidase inhibition considerably enhanced the antitumoral effect of DFMO, a selective inhibitor of ornithine decarboxylase. The combination of polyamine deprivation and administration of well established cytotoxic drugs was expected to improve further the antitumoral effect of polyamine deprivation in Lewis lung carcinoma grafted in mice. Simultaneous treatment, i.e. administration of the cytotoxic drugs during the polyamine deprivation regimen, reduced tumor growth, but enhanced toxic effects. By alternating treatment and polyamine deprivation (1st day methotrexate (1.7 mg/kg), 2nd day cyclophosphamide (90 mg/kg), 3rd day vindesine (0.25 mg/kg), followed by five days of polyamine deprivation), tumor growth was reduced by 90% and an increase of 64% in the survival time of the animals was observed, demonstrating that a significant enhancement of the efficacy of chemotherapy was achieved without concomitant enhancement of toxic effects.

Animals↗

PubMedDate not supplied

Polyamine deprivation, malnutrition and tumor growth.

Feeding an artificial, essentially polyamine-free diet which contained antibiotics for the decontamination of the gastrointestinal tract and 2-(difluoromethyl)ornithine (DFMO) and N,N'-bis-(2,3-butadienyl)putrescine for the inactivation of ornithine decarboxylase and polyamine oxidase, respectively, retarded the growth of several solid tumors by about 80%. In the present work the contribution of the major components of the treatment were analysed, using Lewis lung carcinoma growing in the hind leg of female C57BL mice. In addition to polyamine deprivation, malnutrition due to decreased food intake turned out to contribute significantly to tumor growth retardation. Ornithine decarboxylase was shown to be incompletely inhibited by administration of DFMO with the diet. A considerable improvement of polyamine deprivation can be expected from the continuous administration of this drug, or from analogous inhibitors with more favourable enzyme- and pharmaco-kinetic properties.

Animals↗

PubMedDate not supplied

Accumulation of polyamine analogs in red blood cells: a potential index of tumor proliferation rate.

It has previously been demonstrated that during Lewis lung carcinoma (3LL) growth, red blood cell (RBC) spermidine (Spd) levels change concominantly with the tumor volume and [14C] Spd accumulates in proportion with the tumor volume, if [14C] putrescine (Put) is administered. In the present study we substituted a non-radioactive analogue for labelled Put with the aim to perform human studies, should the method prove suitable to quantify malignant cell proliferation intensity. 2-Methylputrescine (2MPut) is an excellent substrate of spermidine synthase and is transformed in vivo into methylspermidine (MSpd) and 6-methylspermine (6MSpm). After a single i.p. dose of 2MPut, MSpd accumulated in RBC of mice with 3LL xenografts. The concentration of MSpd correlated directly with tumor progression. No significant amounts of MSpd were found in RBC of normal mice. It appears that 2MPut has the potential to become a new tool in tumor diagnostics.

Animals↗