Polyamines localization

Eflornithine (Vaniqa) is an irreversible inhibitor of ornithine decarboxylase, which catalyzes the rate-limiting step in the biosynthesis of polyamines. Polyamines are required for cell division and differentiation, and inhibition of ornithine decarboxylase affects the rate of hair growth. Topical eflornithine has been shown to be effective in reducing facial hair growth in approximately 30% of women when applied twice daily for 6 months of therapy. Hair growth was observed to return to pretreatment levels 8 weeks after discontinuation. Local adverse effects include stinging, burning, and folliculitis. 

Specific uptake systems may account for selective localization in tissues, and this may be the explanation for toxic effects in those particular tissues. For example, the herbicide paraquat (Fig. 3.16) is taken up by the polyamine transport system into the lungs and thereby reaches a toxic concentration (see chap. 7 for a detailed description of this system). 

Fig. 3.13 Method of local bifunctionalisation of oligo-/polyamine dendrimers...

Kaur-Sawhney, R., H. E. Flores, A. W. Galston (1981), Polyamine Oxidase in Oat Leaves A Cell Wall Localized Enzyme, Plant Physiol. 68, 494-498. 

A novel method to localize and treat tumors by means of a ligand-radioisotope complex attached to an antibody is now being tested. The cyclic polyamines are ideal ligands for this purpose because they can be attached to an antibody and form strong complexes with the appropriate radioactive metal ions (Cox et al., 1989 Craig et al., 1989 Kaden et al., 1989 Moi et al., 1987, 1988 Morphy et al., 1988, 1989 Parker et al., 1989 Riesen et al.,... 

The high concentration of OCT is in hepatic tissue relative to other tissues this leads to this enzyme being regarded as a liver-specific enzyme. OCT is localized in the periportal mitochondria and is the second of the five enzymes in the urea cycle. The enzyme measurement should not be confused with ornithine decarboxylase (ODC), which is of interest in studies of polyamine metabolism. The use of the method has been limited by some of technical requirements for the older assays, but newer enzymatic methods may increase its use (Peltenburg et al. 1991 Isobe, Matsuzawa, and Nagamura 1993 Ishikawa et al. 2002). In a number of rat studies, ALT was found to be more predictive of hepatotoxicity than OCT (Bondy et al. 2000). 

At physiological pH in plants, polyamines exist as proton-ated forms. These protonated forms bind to the negatively charged phospholipid head groups and other anionic sites in membranes and alter the stability and permeability characteristics of such membranes. Polyamines also stabilize chloro-plast thylakoid membranes and retard chlorophyll loss in senescing barley leaf tissue. Polyamines also influence membrane fluidity, affect membrane localized proton pumps, and alter plant hormone responses, perhaps by competing for... 

The subscripts ND and B refer to nondiamond carbon and boron, respectively. Boron-doped diamond thin-film electrodes possess several properties important for anodic oxygen-transfer reactions. First, high-quahty diamond films are stable and resistant to corrosion in strongly acidic and alkaline media. Therefore, at the anodic potentials used to detect the polyamines, the electrode structure is stable. Second, films may contain sp -bonded nondiamond carbon impurity distributed very locally over the surface. These impurities can exist at the grain boundaries or as extended defects within the diamond film. These surface impurities, which... 

Diamine oxidase (DAO) is a highly active degradative enzyme of the polyamine metabolic pathways, catabolizes a variety of substrates including histamine and diamines, and is localized to the mature villus epithelial cells of rodent intestinal mucosa (Wolvekamp and de Bruin 1994 John-Baptiste et al. 2012). Although blood DAO activity level correlates with both DAO expression in the villi of the small intestinal mucosa and the severity of small intestinal mucosal lesions induced by anticancer drugs, DAO measurement is confounded by the fact that plasma levels rise markedly upon heparin stimulation prior to blood draws, with peak elevations between 30 and 60 min (Luk et al. 1980, 1981 Tsunooka et al. 2004). 

Polyamines, such as spermine, spermidine, putrescine, cadaverine, are natural substances widely distributed in vegetable, animal and bacterial cells. They enter in the composition of bacterial viruses. They have a wide range of effects, but they are difficult to localize within the cell and their physiological significance is not understood very well. In animal cells and sera there exists a diamineoxidase which converts spermine into highly cytotoxic compounds, and many effects seen in tissue cultures are attributed to these substances. 

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