this study was conducted to evaluate the effects of exogenous polyamines, isopropyl ester, 2, 4-d and naphthalene acetamide application on yield and quality of date palm of ‘kabkab’ cultivar. the inflorescences sprayed with 2, 4-d isopropylester (0, 10, and 20 mg l-1), naphthalene acetamide (0, 80, and 120 mg l-1), putrescence and spermidine (0, 0.1, and 1.0 mm), three or six weeks after pollin...

Polyamines downregulate immune reactivity. RA is associated with decreased IL 2 production. In this study, we present evidence to suggest that excessive polyamines can contribute to the IL 2 deficiency in RA. Blocking polyamine production with inhibitors of ornithine decarboxylase results in increased IL 2 production by RA PBMC. Moreover, polyamine oxidase (PAO) inhibitors and catalase also inc...

Polyamines are classically known by their names of putrescine, spermine, and spermidine. They are synthesized endogenously from ornithine and are interconvertible. In addition, an exogenous supply of polyamines is provided by dietary intake and by intestinal absorption from the products of bacterial metabolism. Polyamine uptake occurs almost entirely in the gut, and afterward the various forms ...

The migration of IEC-6 cells is inhibited when the cells are depleted of polyamines by inhibiting ornithine decarboxylase with alpha-difluoromethylornithine (DFMO). Exogenous putrescine, spermidine, and spermine completely restore cell migration inhibited by DFMO. Because polyamines are interconverted during their synthesis and catabolism, the specific role of individual polyamines in intestina...

Acetylation of polyamines by spermidine/spermine N(1)-acetyltransferase (SSAT) has been implicated in their degradation and/or export out of the cell. The relationship of SSAT to polyamine pool dynamics and cell growth is not yet clearly understood. MCF-7 human breast carcinoma cells were transfected with tetracycline-regulated (Tet-off) SSAT human cDNA or murine gene. Doxycycline removal for >...

The polyamines are low molecular mass aliphatic amines that can be synthesized by both prokaryotic and eukaryotic cells. The most common are putrescine, spermidhe and spermine (Fig. I ). The intracellular concentrations of these polyamines vary greatly with the proliferative status of the cell, and also in response to a wide variety of stimuli [ 1-31, Induction of polyamine biosynthesis, a deli...

The polyamines are essential for a variety of functions in the mammalian cell. Although their specific effects have not been fully elucidated, it is clear that the cellular polyamines have to be kept within certain levels for normal cell function. Polyamine homoeostasis in mammalian cells is achieved by a complex network of regulatory mechanisms affecting synthesis and degradation, as well as m...

PURPOSE To determine whether polyamines are present in corneal cells, whether corneal cell polyamines can be depleted by blocking the first rate-limiting enzyme in the polyamine synthesis pathway, ornithine decarboxylase (ODC), and whether polyamines are required for proliferation in all three corneal cell types. METHODS Cultured corneal epithelial cells, keratocytes, and endothelial cells we...

Acetylation of polyamines by spermidine/spermine N-acetyltransferase (SSAT) has been implicated in their degradation and/or export out of the cell. The relationship of SSAT to polyamine pool dynamics and cell growth is not yet clearly understood. MCF-7 human breast carcinoma cells were transfected with tetracycline-regulated (Tet-off) SSAT human cDNA or murine gene. Doxycycline removal for >2 d...

The polyamines, spermidine and spermine, were first discovered in 1678 by Antonie van Leeuwenhoek. In the early part of the 20th century their structure was determined and their pathway of biosynthesis established. The polyamines are essential elements of cells from all species. They are required for optimum cell growth, and cells where polyamine production has been prevented by mutation, or bl...