A benzilomino-oxidade (BZAO)-oxidade em portadores de carcinoma esofágico avançado / A Benzylamine-oxidade in patients with advanced esophageal carcinoma

RAcional - A benzilamino-oxidase (BzAO) é uma enzima de substrato fisiológico ainda não totalmente conhecido, presente em todos os tecidos humanos e localiza-se nas células nusculares lisas dos vasos sanguíneos, especulando-se daí que a sua função esteja relacionada a angiogenese...

Light microscopic visualization of semicarbazide-sensitive amine oxidase (benzylamine oxidase) using a cerium method.

Light microscopic histochemical studies to visualize semicarbazide-sensitive and H2O2-generating amine oxidase (SSAOX, benzylamine oxidase, BAOX; EC 1.4.3.6?) are usually performed with the coupled peroxidatic oxidation technique of Ryder et al. [25]. For methodological reasons this procedure has its limitations and was therefore replaced by a more reliable and easier to perform cerium-DAB-H2O2-Co technique. With this method SSAOX was studied in many organs of various laboratory rodents and marmosets and in human placenta. Independent of the species the enzyme was present mostly in the plasma membrane of nearly all vascular and non-vascular smooth muscle cells. However, there was a species-dependence of SSOX activity; the highest amounts of stain were found in gerbils and marmosets. In addition, the enzyme was found in these two species in the capillary endothelium of some extra-nervous tissues. The plasma membrane localization of SSAOX and plasma membrane-associated H2O2 production suggest a functional role for the enzyme different from that of other amine oxidases which appear to be primarily involved in intracellular amine detoxification or degradation.

On the presence of a clorgyline resistant benzylamine oxidase activity in mouse kidney.

In the crude homogenates of three different strains (C3H, Swiss, C57b) of mouse kidney the exposure to a millimolar concentration of clorgyline reveals a benzylamine oxidative deaminating activity that is due to a clorgyline resistant amine oxidase (CRAO). In the three strains this CRAO activity shows a low sensitivity to semicarbazide and to alpha- amiguanidine. In the C3H mouse kidney the glycoprotein nature of the CRAO was established from affinity chromatography with immobilized concanavalin A. Studies of this activity in the C3H mouse kidney revealed the presence of a reversible inhibitor which is precipitated by ammonium sulphate between 35-55% of saturation. The presence of this inhibitor precludes accurate measurement of the CRAO distribution in the different subcellular fractions. The enzyme purified by affinity chromatography, is semicarbazide insensitive. This is the first observation of the presence of a CRAO-semicarbazide insensitive activity in a tissue. The fact that "original homogenate" and the subcellular fractions show some sensitivity to semicarbazide also indicates that a semicarbazide-sensitive amine oxidase (SSAO) is present in the C3H mouse kidney.

Amine oxidases and their endogenous substrates (with special reference to monoamine oxidase and the brain).

The roles of MAO, BzO, DAO and PAO in the metabolism of endogenous substrates and the functional implications of their action and inhibition is reviewed, the emphasis being on MAO on one hand and on brain on the other. The major issues are the following: There is no discrete subdivision into substrates selective for MAO-A, MAO-B, or mixed ones, but rather a continuum. Tissue differences in substrate specificity are not likely to be due to molecular variability of MAO. For the deamination of DA, 5-HT and PEA at least, the relative participation of either MAO form in a given tissue is primarily determined by the relative abundance of the two forms; only at 10(-5) M and above, substrate concentration begins to matter also. In vivo, compartmentation is of paramount importance: since there seems to be more MAO-A than B inside monoaminergic neurons, DA, 5-HT and NA are predominantly metabolized by MAO-A if metabolism occurs mainly intraneuronally. Conversely, since MAO-B is more abundant extraneuronally, e.g. in glia cells, the relative participation of this form increases if a significant portion of these amines is deaminated outside monoaminergic neurons. In vivo, monoamine deamination is reduced concomitantly with the degree of MAO inhibition, whereas signs of increased transmitter function are only observed if enzyme inhibition is at least 80%. This is likely to be the result of the action of compensatory mechanisms such as feedback inhibition of transmitter release and synthesis. BzO is particularly abundant in vascular tissue, lung and bone. Low levels are found in brain. Endogenous substrates and physiological function are not known. DAO also occurs only in minimal amount in brain, if at all. Its principal substrates are histamine and the polyamines, and the disposal of these amines is probably its main function. Of the PAO's, the type of enzyme found in the rat liver attacks the secondary amino groups and may have a more prominent role in the metabolism of polyamines in the brain than in the periphery. Bovine plasma PAO, which attacks primary amino groups, is only found in the serum of ruminants, but not other species. Its function in the metabolism of polyamines is not known.

Amine oxidase in human blood vessels and non-vascular smooth muscle.

The pattern of amine oxidation was studied in human blood vessels at various stages of development, and in tissues with muscular layers made up predominantly or exclusively of smooth muscle. Specific activity of benzylamine oxidase, present in all vascular tissues examined, was higher in vessels than in other tissue; the enzyme, in organs rich in non-vascular smooth muscle, though lower than in blood vessels, was significantly higher than in striated muscle or connective tissue. The localization of benzylamine oxidase activity in smooth muscle, as opposed to connective tissue, may have important physiological implications.

Active-sitve titration of pig plasma benzylamine oxidase with phenylhydrazine.

Pig plasma benzylamine oxidase is a protein containing cupric copper and pyridoxal phosphate. The pyridoxal phosphate is stably linked to the enzyme. Discrepancies in the numbers of active sites per molecule of enzyme are reported in the literature. This paper shows that the fully active pure enzyme contains 3 mol of pyridoxal phosphate per mol, whereas enzymes with a lower specific activity are shown by titration with phenylhydrazine to have a lower pyrdoxal phosphate content.